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
2000-07-24
2002-06-18
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...
C430S032000, C503S207000
Reexamination Certificate
active
06407035
ABSTRACT:
The present invention relates to carbonless copy paper, and more specifically to a carbonless CF recording sheet capable of being run on electrostatic copiers and printers without contaminating the components of the electrostatic device.
BACKGROUND
Carbonless copy systems and other copying systems employing a color precursor and a developer are well known in the art. These systems can comprise two sheets, a transfer or donor sheet which contains a colorless color-forming agent on one of its surfaces which is often contained in pressure rupturable microcapsules and a developer or receiver sheet, which is typically a substrate having a layer of a developer material coated onto its front surface which can react with the colorless color-forming agent to form a visible image. In practice, to produce an image, the two sheets are juxtaposed so that the colorless color-forming agent faces the developer material. Upon the application of pressure, such as a pen, pencil, typewriter, or other writing instrument, the microcapsules are ruptured which releases the colorless color-forming agent. The color-forming agent reacts with the developer material on the developer sheet to form a visible image.
Carbonless papers are widely used in the forms industry. Typically, preprinted forms are compiled into a set or packet such that marking the top form will provide the required number of duplicates. In one instance, the carbonless paper is prepared in precollated sets wherein sheets of various colors and surfaces are packaged in reversed sequence sets wherein the sheets are arranged opposite to their normal functional order. That is, the CF sheet is first in the set with the CB sheet being last, with the required number of CFB sheets therebetween. When the sheets are then printed in a printer which automatically reverses their sequence in the delivery tray, they will end up in the proper functional order for subsequent data entry. Where reversal of the sequence in the delivery tray does not occur, precollated sheets can be arranged in their normal functional order.
Traditionally, carbonless paper forms have been printed by conventional printing techniques, such as offset lithography, etc. With the advent of high speed electrostatic copiers having dependable, high capacity collating systems, has come the natural attempts to print carbonless paper by such techniques. Such attempts initially encountered problems, because the specialty coatings on the sheet would tend to shear or pick off the sheet resulting in contamination of the electrostatic device. Cost prohibitive maintenance to clean the machine on a frequent basis was necessary for satisfactory operation of the copier and production of an acceptable product. The heat and pressure utilized in the electrostatic devices would cause transfer of the coating components to elements of the paper and toner transport systems in the electrostatic device. After a number of sheets were printed, the contamination in the device would cause specks of toner powder to be deposited on the sheet. Many of these aforementioned problems were attributable to the microcapsule coating on the CB sheet. Reformulation and modification of the CB coating resolved many of these problems relating to contamination from the microcapsules and the inadvertent rupture thereof which caused premature release of the encapsulated contents and contamination of the electrostatic device.
Contamination of electrostatic copiers and printers has again become problematic due to changes in the feed and printing mechanisms in recently developed electrostatic devices. The new machines are believed to subject the paper being printed to increased levels of heat and pressure not previously encountered during the electrostatic printing process. The increased heat and pressure as well as the faster speeds associated with the newer devices are believed to be responsible for the current contamination problems encountered when using prior art carbonless systems.
Applicants have discovered that the contamination with the newer electrostatic devices is originating with the CF coating rather than the CB coating. As the CF sheet is fed through the paper transport system of the printer or copier, it encounters various pressure points in the device, such as, for example, feed belts and wheels, retard rollers, pinch rollers and the like. When the sheet is passed through these points, often under elevated temperatures, there is intimate contact between the pressure point and the sheet which can result in contamination of the device with components of the CF coating and have deleterious effects on the continued operation of the printer or copier. Simply increasing the amount of binder in the CF formulation may improve binding of the various CF components and thereby reduce contamination. However, an increase in binder levels typically results in a corresponding decrease in product performance characteristics, such as intensity.
Accordingly, there is a need for a carbonless paper capable of being printed on an electrostatic copier or printer without excessive contamination; a paper capable of being run on a copier or printer without requiring excessive machine maintenance; and a carbonless paper, and in particular a recording paper, having improved binding power to prevent contamination without adversely affecting imaging properties. There is also a need for a method of producing a carbonless form using an electrostatic printer or copier wherein the carbonless paper will not contaminate the components of the device and excessive maintenance is not required.
SUMMARY
This invention provides an improved carbonless copy paper, and in particular an improved carbonless CF recording sheet which is capable of being printed on an electrostatic copier or printer without excessive contamination and without requiring excessive maintenance to enable continued operation of the printer or copier. It has been found that, in accordance with the invention, the binder portion of the CF coating can be increased without adversely affecting imaging properties. In accordance with a preferred embodiment of the invention, polyvinyl alcohol mixed with latex is used to improve binding of the pigments in the CF coating while avoiding film formation which can be detrimental to image intensity and speed of development. In another preferred embodiment, an improved binder based on PVA and starch prepared as a cooked pre-mix is used to provide improved binding of the CF coating without adversely affecting imaging properties.
DESCRIPTION
In describing the preferred embodiment, certain terminology will be utilized for the sake of clarity. It is intended that such terminology include not only the recited embodiments but all technical equivalents which operate in a similar manner, for a similar purpose, to achieve a similar result.
The recording sheet of the present invention may be used in any imaging system in which a color precursor is reacted with a developer to form an image. More particularly, it may be used in pressure-sensitive transfer recording systems, pressure-sensitive self-contained recording systems, and thermal or heat-sensitive recording systems.
In accordance with another embodiment, the recording sheet of the present invention may be used in a photosensitive recording system. Photosensitive compositions, photoinitiators, color formers, wall formers, encapsulation techniques and developer materials useful in photosensitive recording systems are described in U.S. Pat. Nos. 4,399,209; 4,772,530; and 4,772,541 are useful herein. These patents are incorporated herein by reference.
The recording sheet includes a substrate having a front surface and a back surface. The substrate is typically paper but in certain applications it may be made of transparent polymeric materials such as polyethylene terephthalate, translucent substrates, opaque polymeric substrates such as Melinex 329 and Melinex 470 sold by ICI Americas, or polymer coated paper materials such as commercially available photographic papers and plain paper.
Any of the develop
Austin Robert A.
Neeld Bruce A.
Yao Peter C.
Hess Bruce H.
The Mead Corporation
Thompson Hine LLP
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