WO2001066359A2 - Carbonless copy material - Google Patents

Abstract

A carbonless copy form set includes at least a first substrate (e.g., a CB material) and a second substrate (e.g., a CF material), wherein the first substrate (12) comprises a first edge having a first orientation indicia thereon and a first substrate surface (14) coated with a color-forming compound (16) and the second substrate (22) comprises a first edge having a first orientation indicia thereon and a second substrate surface (24) coated with a color-developing compound (26). Accordingly, stacks of CB material, CF material, CFB material, and a combination thereof, can be provided in a suitable orientation for 'pre-printing' prior to initiation of the printing process, wherein the system does not interfere with an image pre-printed on the material.

Description

CARBO1SILESS COPY MATERIAL Field of the Invention

The present invention relates to improved carbonless papers for use in relatively high speed printing processes, such as in electrophotographic copiers, copier/duplicators, and laser printers.

Background of the Present Invention

Carbonless impact marking papers for the transfer of images (i.e., carbonless copy papers) are papers which are capable of producing an image upon application of pressure.

Products employing this chemistry generally comprise at least two reactants, one reactant known as a color-former and the other reactant known as a developer, wherein reaction of the two reactants is prevented until intended, e.g., until activating pressure is applied. This is typically accomplished by encapsulation of one of the reactants. Preferably, a fill solution of the color-forming compound(s) in a hydrophobic solvent is encapsulated or contained in microcapsules. The microcapsules serve the purpose of isolating the reactants from one another and preventing reaction. Once activating pressure is applied to the surface of a top sheet, such as from a stylus (e.g., a pencil or pen) or business-machine key (e.g., a typewriter or impact printer), so that the capsules rupture (i.e., those capsules corresponding to the pattern of applied pressure) under sufficient pressure and the solution of encapsulated color-former is released so that at least two reactants come into contact and a reaction between the previously separated reactants occurs. Because the color-former and the developer form a deeply colored image when reacted, an image forms on the lower sheet. In general, the resulting reaction will, of course, form a colored image corresponding to the path traveled by the stylus or the pattern of pressure provided by the stylus or key. The term "activating pressure" includes, but is not limited to, pressure applied by hand with a stylus or pressure applied by a business machine key and the terms "encapsulation" and "encapsulated compounds" refer to microcapsules enclosing a fill material.

The chemistry used in carbonless papers is of two general types. In one type of carbonless paper, the image results from the reaction between an encapsulated leuco dye color-former and an acid, a phenolic, or acidic clay developer. In another type of carbonless paper, the image results from the formation of a colored coordination compound by the reaction between an encapsulated ligand color-former and a transition metal developer. A preferred construction contains an encapsulated color-former dissolved in appropriate hydrophobic solvent(s) within microcapsules and coated with a suitable binder onto a backside of the donor sheet, sometimes referred to as a "coated back" (CB) sheet. A developer, also optionally in a suitable binder such as a starch or latex, is coated onto the front side of the receptor sheet sometimes referred to as a "coated front" (CF) sheet. The term "suitable binder" refers to a material, such as starch or latex that allows for dispersion of the reactants in a coating on a substrate. Each CB coating contains capsules which, when ruptured, release reagents to produce a color-changing reaction at the adjacent CF coating. The preparation of such capsules and of such carbonless sheets is disclosed in U.S. Pat. Nos. 3,516,846 and 3,516,941.

A wide variety of processes exist by which microcapsules can be manufactured and a wide variety of capsule materials can be used in making the capsule shells, including gelatin and synthetic polymeric materials. A popular material for shell formation is the product of the polymerization reaction between urea and formaldehyde (UF capsules); between melamine and formaldehyde (MF capsules); or the polycondensation products of monomeric or low molecular weight polymers of dimethylolurea or methylolated urea with aldehydes or epoxies.

As stated previously, the two sheets are positioned such that the backside of the donor sheet faces the developer coating on the front side of the receptor sheet. In many applications the front surface of the donor (CB) and receptor (CF) sheets contain preprinted information of some type and the activating pressure is generated by means of a pen or other writing instrument used in filling out the form. Thus, the image appearing on the receptor sheet is a copy of the image applied to the front side of the top sheet.

Constructions containing a first substrate surface, on which is coated the encapsulated color-former, and a second substrate surface, on which is coated a developer, are often prepared. The coated first substrate surface is positioned within the construction in contact with the coated second substrate surface. Such a construction is known as a "set" or a "form-set" construction.

Substrates, with one surface, on which is coated the encapsulated color- former, and a second, opposite surface, on which is coated a developer, can be placed between the CF and CB sheets in a construction involving a plurality of substrates. Such sheets are generally referred to herein as "CFB" sheets (i.e., coated front and back sheets). Of course, each side including color-former thereon should be placed in juxtaposition with a sheet having developer thereon. CFB sheets are also typically used in form-sets. In some applications, multiple CFB sheets have been used in form-sets. These contain several intermediate sheets, each having a developer coating on one side and a coating with capsules of color-former on the opposite side. Thus, the sheets in the form-set are sequenced in the order (from top to bottom) CB, CFB(s), and CF. This insures that in each form-set a color former and a color developer will be brought into contact when the microcapsules containing the color-forming material are ruptured by pressure.

An alternative to the use of CB, CF, and CFB sheets is the self-contained (SC), or autogenous, carbonless paper in which both the color-former and developer are applied to the same side of the sheet and/or are incorporated into the fiber lattice of the paper sheet.

Carbonless paper is often used in pre-printed form-sets for preparing multiple copies of receipts, bills, and other business forms and form-sets are prepared by collating from 2 to 8 sheets of carbonless paper. Typically, preprinted forms are compiled into a set or packet such that marking the top form will provide the required number of duplicates. If the number of duplicates is greater than about 3, (i.e., a 4-part form set) the carbonless paper is often manufactured on low basis weight paper so that the pressure exerted on the top sheet will rupture the capsules on the fourth and subsequent sheets in the set. This ability to form a good, dark legible image on a bottom sheet of a form-set from pressure applied on a top sheet, is known as "manifolding."

Form-sets are typically made by applying an adhesive to the edge of a stack of sequenced (i.e., collated) carbonless paper. Each of the coated sheets in a form- set is somewhat porous and permits the adhesive to penetrate into the pores of the paper, such penetration being necessary to attain satisfactory adhesion of sheets within the form-set. Adhesives useful for edge-padding carbonless papers are described, for example, in U.S. Pat. No. 5,079,068. The adhesively bound papers are then "fanned-out" to be separated into individual form-sets. To promote separation, carbonless copy paper form-sets often have a release coating (for example, a fluorocarbon or silicone coating) applied to at least one of the outer faces of each form-set. These coatings are often referred to as "pad coats." Pad coats function as a release coating (i.e., a non-adhesive) to provide low adhesion properties to the outer faces of a form-set; as a release agent for the edge-padding adhesive; and to promote "fan-out properties" in edge- padding to allow the adhesively edge-padded stack to "fan-out" or "fan-apart" and separate into individual form-sets upon fanning. Individual form-sets are prepared by stacking the collated carbonless paper, trimming, edge-padding with an edge- padding adhesive, and fanning-out. "Fan-out" is a method of separating a stack or pad of multiple form-sets into individual form-sets.

Carbonless paper is widely used in the forms industry and carbonless paper forms have been printed in the past by conventional printing techniques such as offset printing, lithography, etc. With the advent of high speed electrophotographic copiers, copier/duplicators, and laser printers having dependable, high capacity collating systems and enhanced copy quality, there has been a movement to replace offset printing equipment located in print shops and large "quick-print" installations with electrophotographic copiers.

Thus, there exists a demand for "pre-printing" information on such carbonless paper, typically using a toner-based printing system in which an image is generally transferred by a variety of printing methods, including electrography or by other non-impact methods.

EP0027698 discloses a sheet material carrying an unobtrusive image and a method for producing same in which an ink jet technique is used to form such a image on ordinary uncoated paper, or on the uncoated face of CB or CF paper or on the coated face of CB, CF or CFB paper, the image being formed after the coating has been deposited on the paper and thus on top of the coating. However, the intensity of the image which can be formed on such coatings without seriously impeding the function of the coating is strictly limited to the formation of unobtrusive images as detailed in the aforesaid specification, and accordingly such images are of minimal value in either identifying the material or conveying other information as called for above, and certainly not of value in readily distinguishing one face from the other.

U.S. Patent No. 5,510,311 describes one solution to the problems mentioned above by providing a copy material of the type having on one face of the material a coating incorporating a substance which when released onto a receptor material produces a visible mark, and having the opposite face of the material free from such a coating, characterized in that one face of the material carries a visible image formed thereon before, the deposition of said coating, which is translucent, so that said visible image is discernable through the coating. Thus, when sheets of copy material is in the form of a stack, all the sheets in the stack have their respective faces provided with the coating facing towards the same end of the stack.

Summary of the Invention

What is yet needed is a system by which stacks of CB material, CF material, CFB material, SC material, and a combination thereof, can be provided in a suitable orientation for "pre-printing" prior to initiation of the printing process, wherein the system does not interfere with a predetermined graphic pre-printed on the material.

One aspect of the present invention provides a method for creating a form set including a first substrate and a second substrate, wherein the first substrate comprises a first edge having a first orientation indicia thereon and a first substrate surface coated with a color-forming compound and the second substrate comprises a first edge having a first orientation indicia thereon and a second substrate surface coated with a color-developing compound. The method includes inserting a plurality of the first substrates into a first substrate container of a printing device and orienting the plurality of the first substrates within the first substrate container using the first substrate orientation indicia; inserting a plurality of the second substrates into a second substrate container of the printing device and orienting the plurality of the second substrates within the second substrate container using the second substrate orientation indicia; printing a predetermined graphic on each of the plurality first substrate and the plurality of the second substrates; and collating the first substrate with the second substrate to create a form set wherein the color- forming compound is in contact with the color-developing compound by virtue orienting the plurality of the first substrates and the second substrates according to the first substrate orientation indicia and the second substrate orientation indicia, respectively. Preferably, preprinting the predetermined graphic on each of the plurality first substrate and the plurality of the second substrate occurs after collating the first substrate and the second substrate.

A method in accordance with the present invention can also include providing a plurality of a third substrate having at least one edge comprising orientation indicia, wherein each of the third substrates includes a first surface coated with a color-developing compound and a second surface coated with a color-forming compound.

Another aspect of the present invention provides a pre-collated form set including a plurality of a first substrate having at least one edge comprising orientation indicia, wherein each of the first substrates includes a first surface coated with a color-forming compound; and a plurality of a second substrate having at least one edge comprising orientation indicia, wherein each of the second substrates includes a first surface coated with a color-developing compound, wherein the orientation indicia on the plurality of the first substrate and the plurality of the second substrate will result in the first surface coated with a color- forming compound of the first substrate contacting the first surface coated with a color-developing compound of the second substrate in a collated form set. The form set may further include a plurality of a third substrate having at least one edge comprising a third orientation indicia, wherein each of the third substrates includes a first surface coated with a color-developing compound and a second surface coated with a color-forming compound. Yet another aspect of the present invention provides a first substrate for creating a form set with a second substrate, wherein the first substrate includes a first substrate surface coated with a color-forming compound; and a first orientation indicia on a first edge of the first substrate, wherein the first orientation indicia functions in conjunction with a second substrate orientation indicia on the second substrate, wherein the second substrate comprises a second substrate surface having a color-developing compound coated thereon such that the color- forming compound contact the color-developing compound in a form set.

A further aspect of the present invention provides a system for creating a form set that includes a first plurality of a first substrate comprising a first substrate surface coated with a color-forming compound, wherein at least one edge of the first plurality has a first substrate orientation indicia thereon; a second plurality of a substrate comprising a second substrate surface coated with a color-developing compound, wherein at least one edge of the second plurality has a second substrate orientation indicia thereon; and a collating device comprising a first substrate container and a second substrate container, wherein the first substrate is collated with the second substrate to create a form set wherein the color-forming compound is in contact with the color-developing compound by virtue orienting the first plurality of the first substrates and the second substrates according to the first substrate orientation indicia and the second substrate orientation indicia, respectively.

In any of the aspects of the present invention described above, the color- forming compound is present in a plurality of microcapsules. Preferably, in one embodiment, the microcapsules includes a shell which is a reaction product of the pair selected from the group consisting of urea and formaldehyde, melamine and formaldehyde, and polyisocyanate and polyamine. In another embodiment, each of the plurality of microcapsules includes a shell of a material preferably selected from the group consisting of gelatin, albumin, starch, agar, carboxymethylcellulose, gum arabic, and a combination thereof. In any of these embodiments, the color-forming compound is preferably present in each of the plurality of microcapsules in an amount of about 0.2 to about 10% by weight based on total fill weight of the of each of the microcapsules. Preferably, the color- forming compound is selected from the group consisting of fluorans, rhodamines, triarylmethane lactone compounds, and a combination thereof.

In any of the aspects of the present invention described above, the color- developing compound is preferably selected from the group consisting of Lewis acids, salicylic acids, phenolic compounds, acidic clays, and a combination thereof.

Brief Description of the Drawings

Figure 1 is a schematic illustration of one embodiment of a form set. Figure 2 is a schematic illustration of a plurality of substrates including orientation indicia in accordance with the present invention.

Figure 3 is a schematic illustration of a method of making a form set in accordance with the present invention.

Detailed Description of the Invention As noted above, carbonless paper is often collated into form-sets that preferably include from 2 to 8 sheets of carbonless paper. It will be appreciated that proper orientation of the individual sheets in a form-set is such that a coated surface of one substrate is in contact with a coated surface of another substrate such that a color-forming compound and a color developer will be brought into contact by application of pressure and/or heat.

Carbonless paper is often first prepared and packaged in "singles" or "precollated" form in paper reams. Subsequently, it may be collated, and optionally padded, and packaged into a form-set. In collating to one version, referred to as a "straight sequence form-set," the sheets are arranged in the order in which they will appear in the finished form. For example, the sequence of sheets in a straight sequence set is as follows:

For 2-part sets:

First Sheet: CB (coated back) sheet Second Sheet: CF (coated front) sheet For 3 -part sets:

First Sheet: CB sheet

Second Sheet: CFB (coated front/back) sheet

Third Sheet: CF sheet

For 4-part sets:

First Sheet: CB sheet

Second Sheet: CFB sheet

Third Sheet: CFB sheet Fourth Sheet: CF sheet

Alternatively, in collating to another version, referred to as "reverse sequence form-sets," sheets of various colors and surfaces are arranged opposite to their normal functional order. When sheets are arranged in this manner and are printed in a printer or copier that automatically reverses the sequence, such that the sheets will end up in the delivery tray in the proper order for subsequent padding and data entry. For example, the sequence of sheets in a reverse sequence form-set is as follows:

First Sheet: CF sheet

Second Sheet: CB sheet

For 3-part sets:

First Sheet: CF sheet

Second Sheet: CFB sheet

Third Sheet: CB sheet

For 4-part sets:

First Sheet: CF sheet

Second Sheet: CFB sheet

Third Sheet: CFB sheet

Fourth Sheet: CB sheet The type of sequenced form-set used for a particular printing operation is a function of the printing machinery. Regardless of the sequenced form-set used, it is preferable to preprint the carbonless paper sheets with a predetermined graphic that can include form information that depends upon the end-use of the form-set, e.g., receipts, bills, applications, and other business forms that typically require multiple copies. In many instances, preprinting the carbonless paper sheets occurs simultaneously with collation, as indicated above with respect to the typical versions of the form-sets. Thus, maintaining correct orientation of each sheet (or substrate) is essential so that the resulting form-set is functional, i.e., the appropriate coated surface of each substrate is brought into contact so that an image can be formed upon application of pressure and/or heat to the form set.

For example, Figure 1 shows a 2-part straight sequence form-set 10, described above, in the appropriate orientation. In particular, a first substrate 12 includes a surface 14 coated with a color-forming composition 16 while a second substrate 22 includes a surface 24 coated with a color-developing composition 26. In use, a plurality of individual substrates or sheets, also referred to herein as a stack, is placed into a substrate container, preferably a sheet feeder mechanism, associated with the printing apparatus. If the stack is placed in an inverted position relative to that required for printing on the appropriate face of each sheet, then the production from the entire stack of sheets will be lost. In practice the visual appearance of the opposite faces of each sheet, and correspondingly the exposed faces of the sheets at opposite ends of such a stack, may not be readily differentiated and accordingly this risk is quite substantial. Moreover, the error may not be detected until the wrongly printed material is incorporated into multi-part sets, giving rise to even greater loss.

In accordance with the present invention, a system for maintaining correct orientation of each substrate is provided that includes orientation indicia located on at least one edge of a stack substrates. As shown in Figure 2, a stack 40 of a plurality of substrates 42 is shown that includes identification indicia 44 according to the present invention. In general, the indicia 44 can be of any character so as to provide orientation and other product information about the substrates to the user. For example, it may be simply an arrow that may be accompanied with such phrases as "this end up," "top side," "print side," "primary print side" and the like. The indicia may include a company trade designation and/or a product trade designation, such that correct orientation of the substrates is indicated by virtue of the correct orientation of the indicia read by the user. Other indicia may be included in the present invention, for example, a brand name, a water mark, or other information concerning the material, such as its weight and/or composition and/or its coatings etc., in such a manner that it can be identified not only by the immediate user but also by subsequent recipients. As will be appreciated by those skilled in the art, the correct orientation of each individual substrate could also be determined if the orientation indicia is observable by the user.

Furthermore, it is contemplated by the present invention that the orientation indicia may include characters in one or more colors. For example, when the orientation indicia includes two or more colors, the orientation of an individual substrate may be determined by virtue of the orientation of the colors on each substrate.

Typically, the stack 40 is a ream of substrates that generally includes about 500 substrates, however, the stack may be of any size so long as the indicia is observable, preferably, legible. As mentioned above, the "stack" may consist of a single substrate so long as the indicia is observable to the user. The orientation indicia may be printed on a stack of substrates by any conventional printing method, such as by inkjet printing, flexographic printing, an inked roller, and the like. The indicia may be printed using any type of colorant so long as it is easily visible to the user, with colorant compositions suitable for use in inkjet printing techniques being preferred. Because the indicia appears on the edge of the stack, a wide variety of colors are suitable because there is little chance that the printed indicia in accordance with the present invention will interfere with the printing on the substrates that may be utilized in the form-set.

Thus, where the substrates are, as is usually the case, cut into sheets prior to such printing, the present invention provides a system by which the sheet material is fed into the printing apparatus with the correct face uppermost. In operation, each substrate type can then be easily fed into a printing apparatus 50, as shown in Figure 3. A stack 52 of sheets 62 of CB material including indicia 63 is placed in position on a sheet feeder so that the front face is uppermost, as indicated by the orientation of the indicia 63. Each sheet is then fed into a printing station 53 at which a predetermined graphic, such as a form template, company trade designations, or other image is applied to the front face. A stack 54 of sheets 64 of CFB material is placed in position on a sheet feeder so that the surface having the color developer thereon is uppermost, as indicated by indicia 65. Each sheet is then fed into a printing station 55 at which a predetermined graphic is produced on top of the surface having the color developer thereon. A stack 56 of sheets 66 of CF material is placed on a sheet feeder with the surface having the color developer thereon is uppermost, as indicated by indicia 67. Each sheet is fed into a printing station 57 at which a predetermined graphic is produced on top of the surface having the color developer thereon. Typically, the predetermined graphic produced on each of the sheets 62, 64, and 66 is identical so that upon collation of these sheets with each other, the predetermined graphic on a particular sheet is substantially in register with the predetermined graphic on the sheet(s) above and/or below it, thus creating a form set.

The printed sheets are then collected into a form set 58 that includes a preprinted CB material 62, with the preprinted surface uppermost and the color- former on a lowermost surface, a middle sheet of CFB material 64 with a preprinted color-developer on the uppermost surface and the color-former on a lowermost surface, and a bottom sheet 66 of CF material with the preprinted color- developer on the uppermost surface, and face 38a lowermost. It will be understood that printing may also be applied to the lowermost surface of the CF sheet 62 if required, preferably before the CF coating is applied to the surface thereof. Thus, in one embodiment of the present invention, a three-part straight form set can be reliable and quickly assembled using orientation indicia as described herein. One with ordinary skill in the art will readily appreciate that various modifications can be made to the printing system described above. For example, instead of collating the various substrates into form sets after the printing operation as described above, it is possible to provide indicia on collated form set stacks before the printing operation is carried out. It will be appreciated that such a stack may comprise alternate CF and CB sheets to produce two-part sets, or sequences of CF and CB sheets separated by one or more CFB sheets to produce sets with more parts. It will be further appreciated that SC substrates (i.e., materials having both the color-forming compound and the color-developing compound coated on the same surface of the substrate) may be collated with any of the above substrates to create a form set.

Substrate(s)

As mentioned above, a preferred construction contains an encapsulated color-former dissolved in appropriate hydrophobic solvents) within microcapsules and coated with a suitable binder onto a backside of the donor sheet, sometimes referred to as a "coated back" (CB) sheet or substrate. A developer, also optionally in a suitable binder such as a starch or latex, is coated onto the front side of the receptor sheet sometimes referred to as a "coated front" (CF) sheet or substrate. The term "suitable binder" refers to a material, such as starch or latex that allows for dispersion of the reactants in a coating on a substrate. Each CB coating contains capsules which, when ruptured, release reagents to produce a color- changing reaction at the adjacent CF coating. Optionally, intermediate substrates having one surface coated with the encapsulated color-forming compound, and a second, opposite surface, coated with a developer, can be placed between the CF and CB substrates. Such sheets are generally referred to herein as "CFB" sheets (i.e., coated front and back sheets). Of course, each side including color-forming compound thereon should be placed in juxtaposition with a sheet having developer thereon. To create a form-set, the appropriately oriented substrates are secured to each other such as by an adhesive, as is known in the art, along one edge. When activating pressure is applied to the front side of the donor sheet, the capsules rupture and release the color-forming compound for transfer to the receptor sheet, forming a colored pattern due to reaction with the acidic developer. If desired, one or more additional substrates that are coated on one side with a developer and coated on the other side with the color-forming compound may be used between the previously mentioned donor and receptor sheets. Color-forming compounds useful in carbonless paper products preferably should be capable of being encapsulated. A wide variety of processes exist by which microcapsules can be manufactured and a wide variety of capsule materials can be used in making the capsule shells, including gelatin and synthetic polymeric materials. Three methods that have achieved commercial utility are referred to as in-situ polymerization, interfacial polymerization, and coacervation encapsulation. Popular materials for shell formation for in-situ polymerization include the product of the polymerization reaction between such materials as urea and formaldehyde (UF capsules), melamine and formaldehyde (MF capsules), and monomeric or low molecular weight polymers of dimethylolurea or methylolated urea and aldehydes. Popular materials for interfacial polymerization include reaction of a polyisocyanate with a polyamine. The preparation of capsules by in-situ and interfacial polymerization and of carbonless sheets employing these capsules is disclosed in European Patent Application 0 539 142 Al. Popular materials for shell formation using coacervation polymerization include gelatin, albumin, starch, agar, carboxymethylcellulose, gum arabic, and mixtures of these materials. Preferably, color-forming compounds can be encapsulated by means of aminoplast polymerization encapsulation. The encapsulation process requires the color- forming compound be dissolved in a solvent or mixed solvents. Thus, the preferred color-forming compounds must be soluble in the solvents used in the encapsulation process. These solvents become the fill solvents. Such solvents are aqueous immiscible solvents and include but are not limited to xylene, toluene, cyclohexane, diethyl phthalate, tributyl phosphate, benzyl benzoate, diethyl adipate, butyl diglyme, vegetable oils, and the like. Suitable solvents are also commercially available under the trade designations SURE SOL (from Koch Refining Co.) and NORPAR (from Exxon Chemical Americas). Preferably, the color-forming compound is present in the microcapsules in an amount from about 0.2 to about 10% by weight based on weight of the fill of the microcapsule. In addition, the color-forming compound should be soluble and non- reactive with the fill solvent used for the encapsulation, insoluble in the aqueous solution used as the dispersing phase, non-reactive with other color-forming compounds present in the encapsulation medium, and non-reactive with the materials used to form capsule walls. Finally, the color-forming compound preferably forms a stable colored image nearly instantaneously upon contact with a receptor sheet. The color reaction helps ensure creation of an accurate, almost instantly readable copy. The stability of the colored image is important because an image that fades over time is generally undesirable.

In addition to their use in carbonless paper, color-forming compounds are used in thermal imaging constructions. These elements rely on the use of heat to produce an image. Thermal imaging constructions generally comprise a support, such as paper, glass, plastic, metal, etc., coated with (a) an acid developable color- forming compound; (b) an acidic developer; and (c) binder. At elevated temperatures the developer reacts with the acid developable color-forming compound to form a colored image corresponding to the pattern in which heat was applied to the thermal imaging construction. The image may be applied by contacting the imaging construction with a thermal print head or by other heating means. Typically, the activating temperature is in the range from 60 to 225°C.

Commonly used classes of color-forming compounds for carbonless paper applications and thermal imaging include fluorans, rhodamines, and triarylmethane lactone color-forming compounds. All of these compounds react with acidic developers, such as Lewis acids, salicylic acids, phenolic compounds, or acidic clays, to form highly colored species by the opening of a lactone ring. Specific, examples of such compounds are Pergascript Black I-R (a fluoran) and crystal violet lactone (a triarylmethane lactone).

When used in a carbonless copy-paper construction, a substrate is coated with a slurry comprising microcapsules filled with a color-forming compound (or mixtures color-forming compounds) dissolved in a suitable fill solvent or solvents, preferably a hydrophobic solvent such that the solution is water-insoluble. The shell of the capsules can be a water-insoluble aminoplast resin formed by polymerization of melamine and formaldehyde. The capsule slurry, may also be combined with a binding agent, such as aqueous sodium alginate, starch, latex, or mixtures thereof for coating on one face of the substrate. In a preferred embodiment, the back of the donor sheet is coated with the capsule slurry, and is referred to as the coated back (CB) sheet. Typically, electron acceptors, e.g., Lewis acids, may be used as developers for color-forming compounds. Examples of such developers are activated clay substances, such as attapulgite, acid clay, bentonite, montmorillonite, acid-activated bentonite or montmorillonite, zeolite, hoalloysite, silicon dioxide, aluminum oxide, aluminum sulfate, aluminum phosphate, hydrated zirconium dioxide, zinc chloride, zinc nitrate, activated kaolin or any other clay. Acidic, organic compounds are also useful as developers. Examples of these compounds are ring-substituted phenols, resorcinols, salicylic acids, such as 3,5- bis(α, -dimethylbenzyl)salicylic or 3,5-bis(α-methylbenzyl)salicylic acid, or salicyl acid esters and metal salts thereof, for example zinc salts, and an acidic, polymeric material, for example a phenolic polymer, an alkylphenolacetylene resin, a maleic acid/colophonium resin or a partially or fully hydrolyzed polymer of maleic anhydride with styrene, ethylene or vinyl methyl ether, or carboxymethylene. Mixtures of the monomeric and polymeric compound mentioned may also be used. Preferred developers are Lewis acids, salicylic acids and particularly zincated salicylic acids, phenolic compounds and particularly zincated phenolic resins, and acidic clays.

The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.

Claims

WHAT IS CLAIMED IS:

1. A method for creating a form set comprising a first substrate and a second substrate, wherein the first substrate comprises a first edge having a first orientation indicia thereon and a first substrate surface coated with a color-forming compound and the second substrate comprises a first edge having a first orientation indicia thereon and a second substrate surface coated with a color-developing compound, the method comprising: inserting a plurality of the first substrates into a first substrate container of a printing device and orienting the plurality of the first substrates within the first substrate container using the first substrate orientation indicia; inserting a plurality of the second substrates into a second substrate container of the printing device and orienting the plurality of the second substrates within the second substrate container using the second substrate orientation indicia; printing a predetermined graphic on each of the plurality first substrate and the plurality of the second substrates; and collating the first substrate with the second substrate to create a form set wherein the color-forming compound is in contact with the color-developing compound by virtue orienting the plurality of the first substrates and the second substrates according to the first substrate orientation indicia and the second substrate orientation indicia, respectively.

2. The method of claim 1, further comprising providing a plurality of a third substrate having at least one edge comprising orientation indicia, wherein each of the third substrates includes a first surface coated with a color-developing compound and a second surface coated with a color-forming compound and collating the first substrate, the second substrate and the third substrate creates a form set wherein the first surface of the third substrate contacts the color-forming compound of the first substrate surface and the second surface of the third substrate contacts the second substrate surface by virtue of the first substrate orientation indicia, the second substrate orientation indicia and the third substrate orientation indicia.

3. The method of claim 1, wherein the color-forming compound is present in a plurality of microcapsules.

4. The method of claim 3, wherein each of the plurality of microcapsules comprises a shell which is a reaction product of the pair selected from the group consisting of urea and formaldehyde, melamine and formaldehyde, and polyisocyanate and polyamine.

5. The method of claim 3, wherein each of the plurality of microcapsules comprises a shell of a material selected from the group consisting of gelatin, albumin, starch, agar, carboxymethylcellulose, gum arabic, and a combination thereof.

6. The method of claim 3, wherein the color-forming compound is present in each of the plurality of microcapsules in an amount of about 0.2 to about 10% by weight based on total fill weight of the of each of the microcapsules.

7. The method of claim 1, wherein the color-forming compound is selected from the group consisting of fluorans, rhodamines, triarylmethane lactone compounds, and a combination thereof.

8. The method of claim 1, wherein the color-developing compound is selected from the group consisting of Lewis acids, salicylic acids, phenolic compounds, acidic clays, and a combination thereof.

9. The method of claim 1, wherein preprinting the predetermined graphic on each of the plurality first substrate and the plurality of the second substrate occurs after collating the first substrate and the second substrate.

10. A pre-collated form set prepared by the method according to claim 1 or 2.

11. A system for creating a form set comprising: a first plurality of a first substrate comprising a first substrate surface coated with a color-forming compound, wherein at least one edge of the first plurality has a first substrate orientation indicia thereon; a second plurality of a substrate comprising a second substrate surface coated with a color-developing compound, wherein at least one edge of the second plurality has a second substrate orientation indicia thereon; and a collating device comprising a first substrate container and a second substrate container, wherein the first substrate is collated with the second substrate to create a form set wherein the color-forming compound is in contact with the color- developing compound by virtue orienting the first plurality of the first substrates and the second substrates according to the first substrate orientation indicia and the second substrate orientation indicia, respectively.