Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1995-03-03
2001-01-16
Crispino, Richard (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C165S240000, C165S273000, C165S272000
Reexamination Certificate
active
06174404
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and apparatus for producing laminated plastic cards, in particular cards which carry printed matter which is protected by an overlying layer of transparent plastic material.
BACKGROUND OF THE INVENTION
Plastic cards, which carry printed matter such as words, designs, pictures or other printed information on a plastic backing, are widely used for all means of commercial purposes, personal identification, visiting cards and the like. It would be highly desirable to print all such cards by means of laser printers, but this is not always possible in the present state of the art, for the following reasons.
Laser printing machines are known in the art and are widely used for a variety of purposes. Basically, the laser printing process comprises, as a first step, defining the subject matter to be printed in the form of an array of instructions that can be used to control the printing machine. A common way of doing this consists in scanning the subject matter to be printed and registering the results of the scanning in a processor's memory, in the form of an array of digital instructions. Said instructions control the emission of laser rays from a laser source. The laser beams impinge on a cylinder in a pattern controlled by the said instructions and electrostatically charge the surface of said metal cylinder at selectively predetermined spots. The selectively electrostatically charged cylinder passes in the vicinity of a reservoir of coloring matter in powder form. The coloring matter particles are attracted to the aforesaid selectively charged spots of said cylinder and form thereon a desired pattern. A print substrate is then passed into contact with the metal cylinder and the pattern formed by the color particles is deposited thereon. This operation is repeated for each color if a multicolor print is desired, usually four times to provide the basic colors magenta, cyan and yellow plus black, to produce a complete colored image. At this stage a colored image has been formed on the print substrate. In order to stabilize the image, the print substrate is passed between heated rollers, which fix or set the print so that it is permanent and stable.
However, the aforesaid process, while quite effective for a number of applications, cannot be satisfactorily applied for the production of cards which are made of materials sensitive to the combined application of pressure and heat, to which they are subjected in the setting section of laser printers. Hereinafter, these material will be generically referred to as “thermo-mechanically sensitive materials” or “thermo-mechanically sensitive (printing) substrates”. Among such thermo-mechanically sensitive materials or printing substrates are synthetic printing sheets, which, when printed upon and set in conventional laser printers, become damaged to such an extent that they cannot be used at all. If an attempt is made to render the setting conditions of laser printers less severe, in order not to damage the plastic card backing, then the setting is insufficient, the print is not stable, and once again the card is not satisfactorily usable. An example of such synthetic printing sheets are those marketed under the trade mark Teslin® by PPG industries, Inc., Pittsburgh Pa. Teslin® is described as a single layer, highly filed, microporous plastic film, based on polyolefin material and containing about 60% by weight of silica, available in gauges ranging from 7 Mil up to 18 Mil. Its properties have been described by the manufacturer and are known to persons skilled in the art.
It is a purpose of this invention to overcome the difficulties met in laser printing thermo-mechanically sensitive materials, and to produce printed cards having a backing of said materials, which are fully satisfactory and of perfect quality.
It is another purpose to provide laser printed, multilayer cards which are mechanically extremely strong and cannot be separated mechanically, viz. without the application of solvents or heat into the layers of which they are composed.
It is a further purpose to provide such cards which can be printed, and if desired laser printed, on both sides.
It is a still further purpose to provide such multilayer cards that are made of highly pliable sheets and yet are relatively stiff and suitable for uses in which stiffness is a factor.
It is a still further purpose to provide such multilayer cards that are printed, if desired, over their entire area, without blank borders.
It is a still further purpose to provide a method for achieving all the preceding purposes and others that will appear as the description proceeds.
It is a still further purpose to provide an apparatus for achieving the aforesaid results, which apparatus is simple and not expensive to make, nor difficult to use.
Other purposes and advantages of the invention will appear as the description proceeds.
SUMMARY OF THE INVENTION
In this application, the term “substrate” or “print substrate” means any backing on the which printing can be effected, regardless of its form and composition, though particular reference will be made to thermo-mechanically sensitive substrates, as hereinbefore defined. In case of doubt; a simple test will permit to determine whether a given substrate is thermo-mechanically sensitive, in the sense in which this expression is used in the present application. It suffices to pass the substrate between two rollers, heated to minimum 120° C. and pressed against one another with a pressure of minimum 150 Kg. If this operation significantly affects the substrate, as to its physical properties or appearance or other properties relevant to its function as a print substrate, it should be classified as “thermo-mechanically sensitive”.
The terms “picture” or “subject matter” or “graphic subject matter” synonimously indicate any kind of printable or printed subject matter, and therefore comprise, among other things, pictures representing persons or objects, portraits, photographs, letters, words, signs and any figures or images that may be carried by a substrate.
The method according to the invention comprises the following steps:
1—providing a set of digital instructions, such as a computer file, which defines the subject matter to be printed on a card made of a thermo-mechanically sensitive material, which subject matter will be called, for brevity's sake, “picture”;
2—depositing, by conventional laser printer operations, said picture on a substrate made of the aforesaid material;
3—partially setting said picture by radiant heat;
4—juxtaposing to the printed substrate a face transparent coating film or sheet on the printed face and, optionally and preferably, a back coating film or sheet on the rear face of the card; and
4—applying pressure and heat, by lamination or otherwise, to the juxtaposed printed substrate and face coating film or sheet and, if any, back coating film or sheet, to bind them together.
Thereafter, if needed, the card is cut to the desired size, e.g. by means of an electric die cutter.
In a variant of the invention, it is possible to provide the coating film or films with a layer of cold adhesive on the face or faces thereof that will be adjacent to the substrate, and in that case the substrate and coating films will be bonded together by the application of pressure only. In another variant a layer of cold glue or a thermoplastic layer, e.g. of polyethylene, can be applied to the substrate to bind thereto another substrate layer. The coating films are preferably made of a thermoplastic, synthetic material, such as, polyethylene or a polyester.
It has been found that the heat-setting by radiant or IR heat, hereinafter called “provisional setting”, partially but sufficiently stabilizes the picture, so that all subsequent operations of the method according to the invention can be carried out without difficulty, not damaging—and indeed surprisingly improving, as will be explained hereinafter—the print substrate. On the other hand, when the final setting by pressure and heat is carried ou
Crispino Richard
Lorengo J. A.
Pitney Hardin Kipp & Szuch LLP
Supercom Ltd
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