US3294571A

US3294571A - Sheets of coated paper

Info

Publication number: US3294571A
Application number: US279843A
Authority: US
Inventors: Ernst Marc Henri Marie
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-05-18
Filing date: 1963-05-13
Publication date: 1966-12-27
Anticipated expiration: 1983-12-27
Also published as: GB1035498A; FR1388612A; BE631747A; CH383755A; NL292950A; LU43644A1

Description

SHEETS 0E CoATED PAPER Filed May 13. 1963 Wfl T//VG PPESSUR E 2. b II 2.3

#www

United States Patent O 11 claims. (C1. 117-363) The present invention relates to sheets of coated paper for the simultaneous production, in superposition, of an original and a number of copies.

To obtain multiple copies of a document during the preparation of the original either by handwriting or typewriting, it has been known long time to use carbon paper, that is to say a sheet of paper, the verso of which is coated with a fatty substance, loaded with carbon black the paper being inserted between the document and the sheet of paper upon which this document is to be reproduced. These carbon papers offer well known drawbacks, resulting particularly from their high first cost, their brittleness and also from the maculation produced on the hands of the user and on the sheet of paper upon which the document is reproduced.

For the same application, use has also been made of sheets of paper coated so as to allow the transfer of the inscribing made on the recto of a first coated sheet to the recto of another coated sheet placed under the first sheet: only the recto of each sheet being generally coated with a film which can consist of a fatty substance, especially a wax, but these sheets are still subject to the same drawbacks as with carbon papers. The film which cove-rs the recto of these known sheets can yalso be constituted by an organic resin, opaque and of a color differing from the color of the body-paper but apt to become locally transparent under the pressure of the inscribing instrument.

Sheets of paper have also been coated on the recto and the verso, so as to allow also the transfer of the inscribings made on the recto of a rst coated sheet on the recto of at least one other coated sheet placed underneath this first sheet; the layers coating respectively the recto and the verso of these known sheets have different chemical compositions selected so that the bringing together, produced by the inscribing pressure, of one of the constituent substances of the layer coating the verso of the first coated sheet on the one hand and of one of the constituent substances of the layer coating the recto of the sheet placed under the first sheet on the other hand, gives rise to a chemical reaction and to the local appearance of a colored spot on the second sheet which reproduces the inscribing made on the recto of the first sheet. These coated sheets of paper of a known type present several drawbacks.

Sheets of paper are also known which `are coated on both their faces for the simultaneous production, in superposition, of an original and of multiple copies which, each, carry on their opposed faces, thin layers of two different types, the layer of the first type being selected so as toV be able to be locally transferred by the inscribing pressure on the layer of the second type of the sheet placed in contact with said layer of the first type. In a known realization of this type, the transferable layer which covers the verso of each sheet is a mixture of inorganic pigments and of synthetic binders which is frail and apt to stain the fingers or the sheet with which it is in contact.

In another known realization, the transferable layer covering the recto of each sheet includes a white coloring substance, for instance, a size color, a spirit color, a pastel, a.s.o.; this layer has thereby a dense structure, which does not facilitate its adherence to the not transferable layer of the second type, which covers the verso of each ICC sheet and is constituted by a sticky substance', the sensitiveness of coated sheets of paper of this type is consequently small.

The coated sheets of paper according to the invention are also coated on their opposed faces with thin layers of two different types, each layer of the first type being transferable upon a layer of the second type; nevertheless, they do not present any of the drawbacks of the previously mentioned known sheets. They are characterized in that their transferable layer is friable and has a microporous structure.

In a first form of realization of the coated sheets of paper according to the invention, the layer of the second type, not transferable, is slightly adhesive.

In a second form of realization, the layer of the second type, not transferable, has the same microporous structure as the transferable layer but it has a better mechanical strength.

These two forms of realization of coated sheets of paper according to the invention present a high sensitiveness owing to the fact that the adhesion of the two layers with each other is improved by the microporous structure of at least one of these sheets.

When a document is established, either by hand-writing or by type-writing, on the recto of a first sheet of paper coated according to the invention, the formation of a copy of this -document on the recto of a second coated sheet of paper, identcial to the first and placed under it, brings about in a way known per se, a process of transfer of matter either from the recto of the lower sheet to the verso of the upper sheet, or in the opposite direction. This transfer of matter results from the local adhesion produced by an inscribing pressure between the layer of the verso of the upper sheet and the layer of the recto of the lower sheet and also from the fact that 4one of the layers adheres Well and the other one adheres badly to the corresponding paper. The copy by a transfer of matter made according to the invention, is a purely mechanical operation based on a physical phenomenon, that is to say, the adhesion between the layer of the verso of the upper sheet and the layer of the recto of the lower sheet: this adhesion can result from a slight adhesiveness peculiar to the not transferable layer (first form of realization) or from an also microporous structure of the two layers (second form of realization); in this last case, the adhesion of said micro-y porous layers to each other results from their partial interpenetration, the friable transferable layer being, so to say,

welded superiicially to the resistant, not transferable, layer by the inscribing pressure. Since the process carried into effect for the production of copies by means of sheets of paper coated according to the inventin is merely physical, these sheets have a noteworthy stability; the copies produced on these coated sheets do not age and their legibility remains constant in the course of time. The coated sheets still blank can be stocked, before being used, during a very long time without undergoing any change: to end no maculation is possible either on the hands of the user upon contact with other sheets of paper, particularly sheets of paper coated according to the invention, as long as these sheets are not locally subjected to high pressures.

By way of example, two forms of embodiment of sheets yof paper coated vaccording to the invention are described hereinafter and schematically illustrated in the annexed drawing together with their mode of utilization to obtain multiple copies.

In each of the FIGURES 1 and 2 of the annexed drawing are shown, in a transverse section, two sheets of paper coated according to the invention on their recto and their verso, these sheets having identical constitutions and being superposed so that the verso of the upper sheet I is in contact with the recto of the lower sheet II.

In the form ofembodiment illustrated in FIGURE 1,

paper, 1, 1', the recto of which is coated with a thin layer 2, 2', which is fria-ble and clings but slightly to the paper. This layer 2, 2', has a colorwhich differs from the color of the face of the body paper 1, 1', upon which it is applied; if, for instance, the lbody-paper 1, 1', is black, its recto is coated with a white layer 2, 2'. The verso of each sheet I, II, is coated with a thin layer 3, 3' strong and adhering well to the paper 1, 1'. In the present form of embodiment, the layer of the verso 3, 3', is made to be slightly adhesive while the layer 2, 2' of the recto of each sheet I, II is made so as to have a line porous structure; for instance, this layer 2 2', is constituted by a film of an organic resin, with the addition of an amorphous ller intended to make it friable: a film of an organic resin of this type, having a ne porous structure can be laid down on a body-paper, for instance according to one of the process descri'bed in the French patent entitled Fabrication of Coated Paper, applied for on September 9, 1961 under No. P.V. 872,478 and in its first additional certicate applied for on February 23, 1962 under No. P.V. 889,006.

When the handwriting or typewriting instrument, for instance the end of a pencil, the ball of a stylograph, or the type of a typewriter applies upon the recto of the upper sheet I a perpendicular pressure, indicated by the arrow 5, on the one hand a deposit of ink is produced on the layer 2 Which covers this recto: after drying, this deposit constitutes the original inscribing; on the other hand, the pressure 5 is transmitted through the paper 1 of the upper sheet I and through the layer 3 coating its verso, to the layer 2' coating the recto of the lower sheet II; as this layer 2' is friable, it is broken at the accurate place where the pressure is applied. In addition, this pressure suppresses the air interval which may exist between the sheets I, II, and which was illustrated in FIGURE 1 by the Ibroken line a-b: as a result, the pressure 5 applies the layer 3 of the verso of the upper sheet I on the broken -portion of the layer 2 of the recto of the lower sheet II: as this layer 3 is slightly adhesive, when the sheets I and II are separated from each other after the completion of the making of the document and of its copy, the broken fragments of the layer 2 of the recto of the lower sheet II remain adherent to the corresponding zone of the layer 3 of the verso of the upper sheet I: this results, on the one hand, from the fact that this layer 3 adhers strongly to the body-paper 1 of sheet I and, on the other hand, from the fact that the broken fragments of the layer 2' of the sheet II adhere but slightly to the body-paper 1' of this sheet II. If, for instance, the inscribing pressure 5 is applied -by `a type of a typewriter, the portion of the layer 2' of the lower sheet II corresponding exactly to this type is drawn away by the layer 3 of the verso of the upper sheet I when this sheet is separated from the sheet II; this type appears then on the recto of the sheet II with a color which is the color of the body-paper 1', a color which has been selected as differing from the color of said layer of the recto 2'.

According to an important variant, a thin layer of a coloring substance, for instance of lamp black, is inserted between the body paper 1, 1', and the layer 2, 2', coating its recto; this layer is selected so that it adheres more to the body paper 1, 1', as to the layer 2, 2', and in any case, its color is to be different from the color of this layer. In such a case, on account of the local suppression of the layer 2' of the recto of the lower sheet II, the intercalated layer Iof coloring substance appears locally so as to reproduce the inscribings made on the recto of the upper sheet I.

In the case of the form of embodiment illustrated in FIGURE 2, each sheet I and II, is essentially constituted by a sheet of body-paper, 1, 1', the verso of which is coated with a rst thin layer 4, 4', of a coloring substance which adheres slightly to the paper: this first thin layer,

4, 4', is covered with a second thin sheltering layer 2, 2', which is friable and adheres well to the layer 4, 4'. The recto of each sheet I, II, is coated with a single thin layer 3, 3', strong and adhering well to the body-paper 1, 1': this layer 3, 3', may be opaque and of a uniform color, ditering from the color of the coloring substance of the layer 4, 4', of the verso, but this layer 3, 3', of the recto, may be also transparent and in this case, the body-paper 1, 1', itself, must also have a uniform color, differing from the color of the coloring substance, of the layer 4, 4', coating its verso. In the present form of embodiment, the layer of the recto 3, 3', is selected to be slightly adhesive while the outer layer 2, 2', of the verso of each sheet I, II, is selected to have a thin porous substance: for instance, this outer layer 2, 2', of the verso is constituted like the layer 2, 2', of the recto of the form of embodiment illustrated in FIGURE 1.

When the hand-writing or type-writing instrument, for instance the end of a pencil, the `ball of a stylograph or the type of a type-writer applies upon the recto of the upper sheet I a perpendicular pressure indicated by the arrow 5, on the one hand, a deposit of ink is produced on the resisting layer 3 coating said recto: after-drying, the deposit constitutes the original inscribing; on the other hand, the pressure 5 is transmitted, through the paper 1 of the upper sheet 1 and through the layer of coloring substance 4 coating internally its verso, to the second layer 2 which coats it externally; as the layer 2 is friable, it breaks at the accurate place where the pressure 5 is applied. In addition, this pressure suppresses the air interval which may exist between the sheets I, II, and which was illustrated in FIGURE 2 by the broken line a-b. As a result, the pressure 5 applies the broken portion of the lower layer 2 of the sheet I upon the upper layer 3' of the sheet II; as this layer 3' is slightly adhesive, when the sheets I and II are separated from each other after the completion of the inscribing of the document and of its copy, the broken fragments of the layer 2 of the verso of the upper sheet I rernain adherent to the corresponding zone of the layer 3' of the recto of the lower sheet II; this results, on the one hand, from the fact that this layer 3' adheres strongly to the body-paper 1' of the sheet II and, on the other hand, from the fact that the broken fragments of the layer 2 of the sheet I have no connection with the body-paper 1 of this sheet I. Nevertheless, as the broken fragments of the layer 2 of the sheet I adher strongly to the corresponding portion of the layer of coloring substance 4, while this substance adheres practically very slightly to the body-paper 1, said broken fragments of the layer 2, when they are drawn by the layer 3 of the sheet II, draw in turn the corresponding portion of the coloring substance 4 of the sheet I. If, for instance, the pressure 5 is applied by the type of a type-writer, the portion of the layer 4 of the upper sheet I, which corresponds exactly to this type is drawn by the layer 2 on the layer 3' of the recto of the lower sheet II, when this sheet II is separated from the sheet I: this type appears then on the recto of sheet II with a color which is the color of the coloring substance of the layer 4 of the upper sheet I, this color having precisely been selected to differ from the color of the layer 3' of the recto of sheet II in the case when this sheet 3' is opaque and of the uniform color of the Ibodypaper 1 of said sheet II in the case when the layer 4' coating its verso is transparent.

According to a variant of the forms of embodiment illustrated in FIGURES l `and 2, the slightly adhesive layer, 2, 2', and the adhesive layer 3, 3', of each of the sheets of paper coated according to the invention, are selected so as to have both a thin porous substance but the layer 3, 3', is selected to be also resistant While the layer 2, 2', is selected to be friable. In such a case, the inscribing pressure 5 brings about again a local break of the layer 2' of the lower sheet II (FIGURE 1) or of the layer 2 of the upper sheet I (FIGURE 2) and the adhesion of the corresponding fragments of matter to the layer 3 coating the verso of the upper sheet I or to the layer 3 coating the recto of the lower sheet II; nevertheless, as this last layer, 3 or 3', has a thin porous structure but is resistant, it is not broken, not even locally, by the pressure 5: this pressure 5 brings then only a partial penetration of the broken fragments of the layer 2 or 2' -of one of the sheets in supercial pores of the

layer

3 or 3 of the other sheet. This partial penetration of a zone of the layer 2 or 2 in the corresponding zone of the

layer

3 or 3 brings about a sort of local cold welding of the two layers, this resulting, when the sheets I, II, are separated from each other, in the drawing along of the broken fragments of the layer 2 or 2 by the

layer

3 or 3. In the case of FIGURE 2, there is still a transfer of the zone of the coloring substance 4, from the verso of the upper sheet I which is subjected to the pressure 5, on the recto of the lower sheet II.

The making of a sheet of paper, coated, on its recto and its verso, according to the invention, for instance of sheet I in FIGURE 2, will now be described:

One of the faces of a sheet of paper, gray or white, 1, is coated with an aqueous dispersion of lamp black with the addition of a damping product, at the rate of 1 to 1.5 gr. of dry product for one square meter of paper. The drying of this dispersion gives a thin layer 4 of lamp black, slightly adhering to the paper 1. This layer 4 can also be constituted by a colored pigment, deposited from an aqueous dispersion or by a film of black wax. The substance of the layer 4 must only fulfill the following conditions, must be slightly adhesive to the paper 1, be able to produce a film just to allow the coating of a sheet of paper, but not to the extent that, in the process ofthe copying by a transfer, such as previously described, said layer 4 should be separated from the paper 1 in the same way as a film, that is to say by fragments having a large surface, particularly a surface greater than the surface of the point or the type which applies the inscribing pressure. The layer 4, thus formed is then coated, after drying, with a solution of vinyl-chloroacetate in acetone, with the -addition of suitable amounts of an amorphous filler and of an alcohol which does not dissolve said vinyl-chloroacetate, for instance of isanol.

The composition of the solution can be, for instance, as follows After drying, the layer of lamp black 4 is coated by a white opaque film 2 of vinyl chloroacetate which has a thin .porous structure, made friablev by the amorphous filler and which adheres well to the layer of lamp black, 4, which it shelters in same time.

A film having a thin, porous and friable structure of this type can Ibe produced according to one of the processes described in the patent application No. P.V. 872,478 and the additional certificate No. P.V. 889,006, previously mentioned. These known processes consist essentially in using a volatile solution of an organic compound to which was added a volatile solution unable to dissolve said organic compound but miscible with its solvent; the amount of the volatile, but not dissolving, substance is chosen with respect to the amount of solvent and to the respective eva-poration speeds so that, after the complete evaporation of the solvent, a suflicient amount of the non dissolving substance will remain to bring about the deposit of the organic compound by a flocculation. The lms, particularly of organic resins, obtained according to the process, offer effectively a thin porous structure and it is possible to render them friable by the raddition to the initial solution of an amorphous filler. The organic compound can be constituted by a cellulosic resin, for instance a cellulose ether or ester dissolved in acetone and to which is added for instance toluene which does not dissolve either the cellulose ether or ester. It can also be constituted Iby a vinylic resin, a condensation resin of the cyclohexanone, of the polystyrene, of the Iarabic gum, a butadiene resin a.s.1o. T o end, the other face of the sheet of paper I is coated with an aqueous dispersion of an acrylic resin, slightly plasticized, in an amount of 2 to 5 gr. of the dry product for one square meter of paper. The drying of this dispersion brings about the formation of a ilm 3 which adheres well to the paper 1 and has a free surface slightly adhesive. The same result can be obtained from an aqueous dispersion of a suitable body, particularly a slightly plasticized organic resin, such for instance as polyvinylchloroacetate or vinyl propionate; the layer 3 can also be obtained by depositing on the free face of the sheet of paper I a film of a varnish with a basis of organic slightly plastiiied resin (polyvinyl acetate, acrylic resin, shellac or a film of yadhesive wax, for instance doped with butyl-rubber, in an amount of 1 to- 3 gr. per square meter of paper.

The sheets of paper coated according to the present invention offer the following advantages:

(l) They can be handled without staining the fingers of the user and without staining each other when they are disposed in bundles. In the case illustrated in FIGURE 2, this results in particular from the fact that the layer of -coloring substance 4 coating their verso is shelteredby a not coloring and rather resistant layer 2.

(12) They are highly sensitive to the inscribing pressures, in particular on account of the friability of the layer 2 coating one of their faces; they allow thereby the simultaneous production of a large number of copies which are for instance obtained in superposition; with the usual typewriters, even with the ones having a small striking strength, the sheets of paper coated according to the invention allow to obtain simultaneously ten copies, the last one being still perfectly legible.

(3) The coupies of documents `obtained on sheets of paper coated according to the invention have a perfect resistance to deteriorations `and this, in particular, prevents any forgery of these copies, as particularly, i-t is not possible to delete the inscriptions, for instance by a gumming or any other non destructive process.

(4) The sheets of paper coated according to the invention do not undergo any foxing during their ageing, either during the keeping in stock before use or during the keeping of the obtained copies. This advantage results in particular from the fact that the layers coating the faces of the sheets according to the invention are chemically neutral with respect to each other, and this, in particular, allows to keep them in superposition, verso against recto, without any inset as long as wished. This advantage is also connected to the fact that the chemical structure of each of these layers taken individually is perfectly stable in the coursc of years.

(5 Any copy made on a sheet of paper coated according to the invention of the type illustrated in FIGURE 2 'can be read in transparency, provided that the body-paper is sufficiently thin and suiciently transparent. This results from the fact that the inner layer of coloring substance 4 and its outer layer of protection 2, also usually opaque, which cover the verso of the sheet, have been locally destroyed 'by Ithe inscribing 'pressure and that the corresponding fragments have been drawn away by the underlying sheet. This particular of the the copies made on sheets of paper according to the invention can be used for the subsequent making of photocopies.

6) The sheets of paper coated according to the invention allow the making of copies only when they are used in bundles of at least two identical sheets superposed so that the verso of each sheet is in contact with Ithe recto of another sheet: no transfer of an inscribing is possible when using two sheets of paper according to the invention applied one `on -the other by their versos or their rectos, or when using a single sheet of paper, coated according to the invention, applied upon any support.

(7) In the case when a layer of rather thin coloring substance is intercalated between the paper and the transferable layer covering its verso, the portions of the layer of coloring substance which are not drawn away by the transferable layer show on said verso a negative of the inscribings which cannot be falsified and permits subsequent verification, in particular of vouchers or banking documents.

What I claim is:

1. Sheets of paper coated with thin layers of different kinds on their two faces, said coated sheets, when superposed with each face thereof having a coating layer of a lirst kind in contact with another face thereof having a coating layer of a second kind, being adapted to transfer the inscribing made on the upper sheet by a pressureexerting member to all the sheets placed thereunder, each thin coating layer `of a first kind consisting essentially of resin film deposited to have a microporous structure and of an amorphous tiller widely distributed throughout said resin and in an amount suiiicient to render the resin friable -but not over 50% by weight, whereby each coating layer of a rst kind is locally broken into sharply outlined frag- 4ments by the inscribing pressure, whereas each thin coating layer of a second kind is adapted to retain the broken vfragments of the frangible coating layer of a irst kind in contact therewith, when the superposed sheets, the inscribing having been made thereupon, are separated from one another.

2. Sheets of paper coated with thin layers of different kinds on their two faces, said coated sheets, when superposed with each face thereof having a coating layer of a rst kind in contact with another face thereof having a ,coating layer of a second kind, being adapted to transfer the inscribing made on the upper sheet -by a pressure-exerting member to all `the sheets placed thereunder each thin coating layer of a tirst kind consisting essentially of a resin film deposited to have a microporous structure and of an amorphous liller widely distributed throughout the said resin film yand in an amount sul'licient to render lthe resin friable but not over 50% by weight whereby each coating layer -of a irst kind is locally broken into sharply outlined fragments by the inscribing pressure, whereas each thin coating layer of a second kind consists of a .slightly adhesive substance, whereby, when the superposed sheets, the inscribing having been made thereon, are separated from one another, the broken pieces `of each frangible coating layer of a iirst kind are drawn away by the adhesive coating layer 4of a second kind just in contact therewith.

3. The coated sheets of claim 2, in which the organic resin comprised in each microporous coating l-ayer of a first kind is selected from the group consisting of cellulosic resins, vinylic resins, condensation resins of cycloheXanone, arabic gum and butadiene resins.

4. The coated sheets of claim 2, in which each adhesive coating layer of a second kind consists of a water-soluble substance selected from the group consisting of slightly plasticized `organic resins, varnishes containing slightly plasticized organic resins, and adhesive waxes.

5. Sheets of paper coated with thin layers of different kinds on their two faces, said coated sheets, when superposed with each facethereof having a coating layer of a iirst kind in contact with another face thereof having a coating layer of a second kind, being adapted to transfer the inscribing made on the upper sheet by a pressureexerting member to all the sheets placed thereunder, each coating layer of a first and a second kind consisting essentially of a resin iilm deposited to have a microporous structure, whereas each coating layer of a first kind contains in addition an amorphous filler widely distributed throughout the said layer to have a mechanical strength much lower than each coating layer o-f a second kind, whereby .the microporous layers of different kinds which are in contact with each other, are supercially interpenetrated by each other under the inscribing pressure, each frangible coating layer of a first kind being further broken into sharply outlined fragments by said inscribing pressure, and, when the superposed sheets, the inscribing having been made thereon, 4are separated from `one another, the broken pieces of each frangible coating layer of a lirst kind are drawn away by the microporous resistant coating layer of a second kind just in cont-act therewith.

6. The coated sheets of claim 5, in which the organic resins comprised in each microporous coating layer of a first and of a second kind are selected from the group consisting of cellulosic resins, vinylic resins, condensation resins of cyclohexanone, arabic gum and butadiene resins.

7. The coated sheets of claim 5, in which at least each of the microporous, frangible coating layers of a first kind comprises further an amount of 4an amorphous filler not superior to 50% by weight.

`8. `Coated sheets with thin coating layers `of different kinds on their rectos and versos, said coated sheets, when superposed, the verso of each sheet being in contact wit-h the recto of another sheet, being adapted to transfer the inscribing made on the recto of the upper sheet by a pressure-exerting member to the rectos of all the sheets placed thereunder, each recto coating layer consisting essentially of a resin lm deposited to have a microporous structure and of an amorphous filler-widely distributed Ithroughout the said resin lilm in an amount sufficient to render the resin friable but not over 50% Weight, whereby each recto coating layer is locally broken into sharply outlined fragments by the inscribing pressure, an intermediate thin layer of a coloring substance being disposed on the recto of each sheet, under its microporous recto coating layer, this intermediate layer having a color different from that of said recto coating layer and being deposited to adhere more strongly to the sheet than to its recto coating l-ayer, whereas each verso coating layer is adapted to retain the broken fragments of the frangible recto coating layer in contact therewith, when the superposed sheets, the inscribing having been made thereon, are separated from one another.

9. The coated sheets of claim 8, in which the intermediate layer disposed on the recto of each sheet under its microporous recto coating layer, consists of a coloring substance selected from the group consisting of colored pigments and black wax.

10. Coated sheets with thin coating layers of different kinds on their rectos and versos, said coated sheets, when superposed, the verso of each sheet being in contact with the recto of another sheet, being adapted to transfer the inscribing made on the recto -of the upper sheet by a pressure-exerting member to the rectos of all the sheets placed thereunder, each verso coating layer consisting essentially of a resin film deposited to have a microporous structure fand of an amorphous filler widely distributed throughout the said resin film in an amount sufficient t-o render the resin friable but not over 50% by weight, whereby each ,verso coating layer is locally broken into sharply outlined fragments by the inscribing pressure, an intermediate thin layer of a coloring substance being disposed on the verso Uof each sheet under its microporous verso coating layer, said intermediate layer having a color different from that of the recto of each coated sheet and being deposited to adhere less strongly to the sheet than to its verso coating layer, whereas each recto coating layer is adapted to retain the broken fragments of the frangible verso coating layer in contact therewith, together with the parts 0f said intermediate colored layer strongly adhering thereto, when the superposed sheets, the inscribing having been made thereon, are separated from one another.

11. The coated sheets of claim 10, in which the intermediate layer disposed on the verso of each sheet under its microporous verso coating layer, consists of a coloring substance selected from the group consisting of colored pigments and black wax.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Foster 117-363 Brown 117-36.3

Strawn 117-36.3

Dalton 117-367 Quick 117-3621 Rolle et al 117-36.7

1 0 2,898,112 8/1959 Flower et al 117-36.7 3,111,421 11/1963 Newman et al. 117-36.7

FOREIGN PATENTS 1,074,604 2/1960 Germany.

901,028 7/ 1962 Great Britain.

MURRAY KATZ, Primary Examiner.

WILLIAM D. MARTIN, Examiner.

Claims

1. SHEETS OF PAPER COATED WITH THIN LAYERS OF DIFFERENT KINDS ON THEIR TWO FACES, SAID COATED SHEETS, WHEN SUPERPOSED WITH EACH FACE THEREOF HAVING A COATING LAYER OF A FIRST KIND IN CONTACT WITH ANOTHER FACE THEREOF HAVING A COATING LAYER OF A SECOND KIND, BEING ADAPTED TO TRANSFER THE INSCRIBING MADE ON THE UPPER SHEET BY A PRESSUREEXERTING MEMBER TO ALL THE SHEETS PLACED THEREUNDER, EACH THIN COATING LAYER OF A FIRST KIND CONSISTING ESSENTIALLY OF RESIN FILMM DEPOSITED TO HAVE A MICROPOROUS STRUCTURE AND OF AN AMORPHOUS FILLER WIDELY DISTRIBUTED THROUGHOUT SAID RESIN AND IN AN AMOUNT SUFFICIENT TO RENDER THE RESIN FRIABLE BUT NOT OVER 50% BY WEIGHT, WHEREBY EACH COATING LAYER OF A FIRST KIND IS LOCALLY BROKEN INTO SHARPLY OUTLINED FRAGMENTS BY THE INSCRIBING PRESSURE, WHEREAS EACH THIN COATING LAYER OF A SECOND KIND IS ADAPTED TO RETAIN THE BROKEN PFRAGMENTS OF THE FRANGIBLE COATING LAYER OF A FIRST KIND IN CONTACT THEREWITH, WHEN THE SUPERPOSED SHEETS, THE INSCRIBING HAVING BEEN MADE THEREUPON, ARE SEPARATED FROM ONE ANOTHER.