Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Method of use – kit – or combined with marking instrument or...
Reexamination Certificate
2000-10-31
2003-05-13
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Method of use, kit, or combined with marking instrument or...
C503S200000, C503S206000
Reexamination Certificate
active
06562755
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to security inks used to thwart counterfeiting of printed commercial documents such as sales transaction records and receipts. More particularly, the invention relates to the use of security features on thermosensitive recording materials such as thermal paper.
BACKGROUND OF THE INVENTION
Thermosensitive recording materials provide for the generation of print or designs without an ink ribbon by the application of heat energy thereto. Thermal paper is a typical example of a thermosensitive recording medium and typically comprises a base sheet, a base coating and a thermosensitive coating. Special color forming chemicals and additives are present in the thermosensitive coatings such that when heat is applied by a thermal head, the color forming chemicals react to develop the desired print or image.
The most common type of thermosensitive coating is the dye-developing type. There are three main color producing components in a dye developing-type thermal paper which are: a colorless dye (color former), a bisphenol or an acidic material (color developer) and a sensitizer. These solid materials are reduced to very small particles by grinding and incorporated into a coating formulation along with any optional additives such as pigments, binders and lubricants. This coating formulation is then applied to the surface of paper, typically a base sheet and base coating, or other support system using one of the various types of conventional coating application methods and dried. Images are formed on the coated surfaces by the application of heat to melt and interact the three color producing materials.
The use of special inks as a security measure, such as optically variable inks which change color when exposed to a light source other than ambient light and inks which provide latent images, is well known. Optically variable inks include fluorescent compounds which respond to infrared or ultraviolet light. Examples of printing inks which fluoresce under ultraviolet radiation, such as fluorescein, are described in U.S. Pat. Nos. 4,153,593; 4,328,332 and 4,150,997. Thermochromic compounds which change color at different temperatures is another type of optically variable ink. Examples of thermochromic compounds, also referred to as heat activatable chromogenic compounds, are described in U.S. Pat. Nos. 4,425,161; 5,427,415; 5,500,040; 5,583,223; 5,595,955; 5,690,857; 5,826,915; 6,048,347; and 6,060,428. Near-infrared fluorescent (NIRF) compounds provide another form of latent image as a means of security by reflecting radiation in the near-infrared range. Examples of NIRF compounds are described in U.S. Pat. No. 5,292,855, issued Mar. 8, 1994, U.S. Pat. No. 5,423,432 issued Jan. 13, 1995, and U.S. Pat. No. 5,336,714, issued Aug. 9, 1994. To be useful as a security measure on printed commercial documents, latent images must be well camouflaged but readily and easily viewable to the user. Preferably, this is accomplished by a simple procedure, particularly where records are only casually inspected, such as sales receipts and transaction records.
Where security features are desired from special compounds for thermal paper, these compounds must not pre-react the reactive components within the therrnosensitive coating of the thermal paper or prevent the formation of an image on the thermal paper from thermal printing. This will detract from the thermal paper's printing performance. Certain chemical factors can adversely affect and degrade the performance of the thermosensitive coating and should be avoided such as some organic solvents (ketones), plasticizers (polyethylene glycol type), amines (ammonia) and certain oils (soy oil). The use of fluorescent compounds as a security feature for thermosensitive recording materials is described in U.S. Pat. No. 5,883,043. The use of NIRF compounds as a security feature for thermosensitive recording materials is described in U.S. Pat. No. 6,060,426, assigned to the same assignee as the present invention. While techniques for using fluorescent compounds and NIRF compounds as security features for thermosensitive recording materials have been effective, with the ease of counterfeiting made possible through the advent of today's personal computers and color copiers, it is desirable to provide additional and alternative means of security, such as through the use of thermochromic compounds.
To protect thermal paper from environmental conditions, and premature coloration from handling, a number of developments have been made. One is to produce a barrier or protection layer on top of the thermal coating (see U.S. Pat. Nos. 4,370,370; 4,388,362; 4,424,245; 4,444,819; 4,507,669; and 4,551,738). Another approach is to encapsulate the reactive components in microcapsules which rupture or are permeable when exposed to heat. See U.S. Pat. Nos. 4,682,194; 4,722,921; 4,742,043; 4,783,493; and 4,942,150. These protective measures do not always prevent premature coloration of the thermosensitive coating.
U.S. Pat. No. 5,595,955 discloses coating a latent image comprised of a thermochromic ink, referred to therein as a “reversible thermosensitive recording material,” printed on a support with a thin protective layer.
SUMMARY OF THE INVENTION
The present invention provides a thermosensitive recording material such as thermal paper with a thermochromic compound as a security feature printed on the side opposite the thermosensitive layer to prevent counterfeiting. The thermochromic compound is overcoated with a protective coating, preferably UV cured, so as not to pre-react the reactive components of said thermosensitive coating or cause the loss of the color-forming properties of the thermosensitive coating.
The thermochromic compound is shielded from reaction with the reactive components of the thermosensitive coating by a protective coating. This protective coating can be a UV cured coating or an air dried flexographic or lithographic coating. Such shielding preserves the activity of the thermochromic compounds and also the activity of the thermosensitive coating of the thermal paper so that it will still generate color when exposed to heat.
The thermochromic compounds provide a unique mode of security through their change in color in response to heat. Printed images which contain thermochromic compounds and another optically variable compound, such as a fluorescent compound, provide two modes of security.
The present invention also provides a method for preparing a thermosensitive recording medium having a thermochromic compound incorporated therein as a security feature without premature coloration of the thermosensitive layer. This method comprises printing a mark or image on the side of the thermosensitive recording medium opposite the thermosensitive coating using a thermochromic compound and overcoating the thermochromic compound with a protective coating, preferably a UV curable protective coating. The protective coating can be applied by conventional coating processes, such as flexography and lithography, and where necessary, cured. Conventional UV curing techniques can be used where appropriate.
The thermosensitive recording media of the present invention have a base sheet with a thermosensitive coating. Optionally, a conventional base coating is positioned between the thermosensitive coating and the base sheet. The base coating is typically comprised of inert pigments and binders and provides a smooth surface for the thermosensitive coating. This thermosensitive coating is preferably of the dye-developing type. Particularly suitable dye developer systems are those wherein the reactive dyes are colorless or white-colored which become dark colored when melted and exposed to a color developer. Such dyes are typically basic substances which become colored when oxidized by acidic compounds or bisphenol compounds. In these dye-developer systems, sensitizers are typically mixed with the dyes to form a blend with a reduced melting point. This reduces the amount of heat necessary to melt the dye and obtain reac
Halbrook, Jr. Wendell B.
Wehr Mary Ann
Hess Bruce H.
Millen White Zelano & Branigan P.C.
NCR Corporation
LandOfFree
Thermal paper with security features does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermal paper with security features, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal paper with security features will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3080851