Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1998-11-12
2001-05-22
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S457000, C428S458000, C428S459000, C428S460000, C428S461000, C428S462000, C428S463000, C428S464000, C428S465000, C428S466000, C428S692100, C428S332000, C428S425800
Reexamination Certificate
active
06235378
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to magnetic surfaces, and more particularly to a flexible sheet having a magnetic surface. The flexible sheet is safe to handle and able to be cut with common hand tools, such as scissors.
2. Description of the Related Art
In many situations, it is desirable to have a magnetic surface: one to which magnets are attracted and may be attached. For example, in a classroom teachers often must display instructive material to students, but also keep their hands free to write. Large magnetic boards are available for such a purpose, but these must attach to a wall, or rest on an easel.
Magnetic products that are packaged for retail display are commonly mounted to a steel sheet to maintain their relative positions in the package. The steel sheet must be inexpensive, because it will be discarded after it is removed from the packaging. Inexpensive steel sheets are presently sold by Magna Visual, Inc. with MAGNA CHART brand magnetic visual aids. The steel sheets are paper-coated and about 3 to 6 mils thick with admittedly sharp, dangerous edges as evidenced by a warning on the label of the retail packages. The steel is apparently paper coated for appearance purposes and some corrosion resistance, which is due mostly to the adhesive used to mount the paper to the steel.
Sheet steel is also conventionally sandwiched into paper board products for game boards and wall boards sold by Kling Magnetic of Hudson, N.Y. The thickness of the steel sheet ranges from about 3 to 6 mils (0.003 to 0.006 inch). These products are also considered unsafe for ordinary handling due to sharp edges.
In U.S. Pat. No. 5,609,788, Deetz describes a paint composition into which ferrous particles are suspended. Surfaces coated with this paint will attract magnets and hold them in place. Thus, a wall or other surface can be painted to look and function in an ordinary manner, but also provide a magnetic surface. However, the amount of ferrous particles mixed in the paint is limited because the paint must remain spreadable. Therefore, the attraction of a magnet to the painted wall or other surface is relatively small, which becomes a problem if somewhat heavier items must be attached to them. Ten mils of this paint is about 50% as effective in attracting magnets as a 2 mil steel substrate.
Therefore, a long felt need exists for a thin magnetic sheet that is inexpensive, safe for normal or typical handling and convenient to use for a variety of educational, entertainment, and packaging applications which has not been satisfactorily solved by prior efforts.
SUMMARY OF THE INVENTION
The invention comprises a composite sheet. A first polymer layer is laminated to the first major surface of a ferromagnetic substrate having opposing first and second major surfaces. In a preferred embodiment, a second polymer layer is laminated to the second major surface of the substrate, sandwiching the substrate between the first and second polymer layers. The substrate is preferably steel about 3 mils, and preferably about 1 or 2 mils thick.
A significant advantage of the composite sheet is the increased safety for typical handling of the sheet by hand without the need for protective gloves or the like. The polymer layers dull the edges of the steel sheet. Additionally, the composite sheet can be cut easily with scissors, enhancing the ability of the individual user to modify the sheet to his or her needs. Even after the composite sheet has been cut with scissors, it is significantly less likely to cut the user than the steel sheet alone or prior art paper coated steel sheet. This is due to the dulling effect to the edges of the sheet caused by the polymer layers laminated to the steel substrate without the stiffening effect some adhesives and paper have.
An additional advantage is that the polymer layers laminated to the substrate also greatly increase the corrosion resistance. Corrosion of the substrate tends to diminish the appearance of the sheet which is important in many commercial applications.
The present invention results in a safe sheet that has twice the magnetic attraction of the magnetic paint, in one half the thickness. The present invention is also able to be used in a broader range of applications, due to the broad range of adhesives that will adhere to the laminate.
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Foster Jason H.
Kremblas, Foster, Millard & Pollick
Resan Stevan A.
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