US2939009A - Thermotransfer duplicating process - Google Patents

Description

May 31, 1960 J. M. TIEN 2,939,009

THERMOTRANSFER DUPLICATING PRocEss Filed Feb. l, 1956 2 Sheets-Sheet 1 FIG. 4

IN VEN TOR.

May 31', 1960 J. Ml TIEN THERMOTRANSFER DUPLICATING PRocEss 2 Sheets-Sheet 2 Filed Feb. l, 1956 United States Patent Ote 2,939,009 Patented May 3l, i960 2,939,009 THERMOTRANSFER DUPLICATING PROCESS Jack M. Tien, 28 Division St., New York 21, N.Y. Filed Feb. 1, 1956, Ser. No. 562,795

` 22 claims. (ci. 25o-'65) This invention relates to a process and material for use in the reproduction of a graphic subject. More particularly Iit relates to a single operation utilizing heat as the sole agent -for duplication of drawings, typed pages, written pages, and printed pages of a book or the like with my thermo-responsive sheets or on other surfaces bearing my novel coating composition.

Prior arts have resulted `in the recent appearance on the market of two kinds of heat sensitive copy paper: One is the thick copy paper which is white on one side and black on the other. The coating on this paper tends to crumbleoif on b ending or scratching. Also, the duplicated characters are not sharp enough to be entirely satisfactory for commercial uses. The other kind of copy paper, which is pinkish tan in color and resembles onion skin paper, is so thin that the copy has to be backed by a White sheet in order to increase legibility. This paper also changes color on storage and turns dark on exposure to sunlight. The method of using either of the two heat-sensitive papers for duplication involves the positioning of-a graphic original to be copied with a heat-sensitive paper in surface contact and the exposure of the original to a -sucient heat radiation. A copy can be made by heat alone in a matter of seconds without subsequent manipulation. Nevertheless, the duplicates made from these two copy papers are still heat sensitive. In other words, the copies made according to prior arts are only of a temporary nature and the disadvantage is an inherent one. The present invention overcomes these diiculties by thermotransfer and still provides a duplicating process of speed and simplicity.

It is an object of this invention to provide a thermotransfer duplicating system which is substantially free from the lobjectionable features of prior arts. Another object is to provide a new thermotransfer duplicating system with my novel copying material.

Still another object is to provide a thermotransfer system in which the color of the copy can be varied over a wide range including intense black against white background of good quality.

Still another object is to provide a thermotransfer system wherein the copy will not bleed or smear under high humidity or even when immersed in water.

A further object is to provide duplicate copies which are permanent in nature.

Another object of this invention is to provide a new thermotransfer system capable of giving a small number of copies utilizing a single transfer sheet.

Still a further object is to provide -a novel thermotransfer system in which the duplicate is substantially fast to light as well as to heat under normal conditions.

More particularly an object is to quickly provide a planographic printing plate for making multiple copies.

The arts of duplication by transfer are old. Nonreactive and colored carbon paper has been used for a long time. The colorless reactive transfer of Groak as disclosed in U.S. Patent 2,168,098 and that of Green as disclosed in U.S. Patents 2,550,466 to 2,550,469 were Vhas any thermotransfer article .appeared on the market.

GENERAL DESCRIPTION My process is primarily for reproduction of black` and white. However, other colors of graphic subject-matter may also be copied, if some heat absorbent material is incorporated in the ink to make the original.

The process consists chiefly of the following steps:

(1) Preparing a transfer sheet comprising a support bearing thermotransfer material.

(2) Preparing a receiving sheet with absorbent and adsorbent surface.

(3) Placing the transfer sheet and receiving sheet iirst as two-ply combination and then in contact-superimposed relation with the original to be copied.

(4) Irradiating the two-ply combination sutiiciently to obtain a sharp facsimile or la reverse image.

(5) Separating the duplicate from the transfer sheet and the original.

The thermoresponsive material capable of being transferred, when heated, (or thermotransffer material) may be contained in the hydrophilic colloid microcapsules or in the waxy microparticles or may be in the form of liquid microdroplets entrapped yin a continuous film of the suitable binders or may be carried in a mixture of waxy substances.

PRINCIPLES OF THE PROCESS Upon heating the printed page by infrared radiation,

i the black parts of the graphic original absorb the radiation and convert it to heat which travels to the transfer sheet by conduction and 4causes rupture of the barrier around the thermotransfer material according to the patterns to be copied. Thus, the thermotransfer material is released in the liquid state, in which form it is taken up by the surface of the receiving sheet.. Thereby a detachable facsimile or `a reverse image is produced.

Apparently all the copying materials employed in my process must be sufficiently transparent to infrared radiation and suiciently low in thermoconductivity. Otherwise, the process is inoperable.

DETAILED DESCRIPTION The following examples and the accompanying figures are given merely to demonstrate the principle of this invention and to insure a clear and thorough understanding of my thermotransfer process and the spirit of this invention is not limited thereby.

The expression color former is to be understood as a colorless material which makes other colorless materials assume color by sufficient contact. In the following examples all parts or percentages are by weight, and the collo-id solutions are all aqueous, unless otherwise specied.

Example 1 l-l Transfer sheet-The suspension of waxy microparticles is made by spraying the hot wax-dye melt (through a cold chamber, if desired), into an 8% starch solution. The hot melts consist of 60% hard paraflin wax, 38% light paraiiin oil and 2% 1,4-dtoluido-anthraquinone blue. The suspension is coated on a sheet of onion skin paper in a thickness of -about one mil. Instead of blue, any other oil soluble color may be used, except black. Instead of paraflin wax, carnauba wax, bees wax, sugar cane wax, mortan wax, Chinese wax or its mixture may be used.

1 2 Receiving sheen-The slurry is made of one volume of coating kaol-ingand one volume of 20% casein solution, which is prepared as ammonium caseinate in the conventional manner. The paper is coated with this slurry in a thickness of about one-half mil.

Example 2 21 Transfer sheet.-Four parts of 20% casein solution in the form of sodium caseinate and 3 parts of 10% iron stearate in diamyl adipate (if desired, the dark 1.5% bienzoyl leuco methylene blue in chlorinated bibrown solution can be reduced to a very faint yellow If desired, formaldehyde may be added to the salt solution to harden the casein shell. The casein microparticles thus formed are washed with water until free of all salt. The paper is cast coated with this microparticle slurry in a thickness of -about one mil. Instead of casein, starch, animal gelatin or polyvinyl alcohol may be used. Instead of diamyl adipate, other dialkyl adipate, dialkyl sebacate or dialkyl phthalate may be used.

2-2 Receiving sheets-'The slurry is made of two parts coating clay, one part of hexamethylenetetramine-pyro gallic acid, one part of starch and six parts of water. A sheet of paper is coated with this slurry in a thickness Vof about one-half mil. The copy pattern will be black.

Example 3 l have found that the commercial pressure sensitive paper can also be used as ther-motransfer paper with fairly good result in `spite of the claim that the paper is workable only by impact pressure but under no other conditions (column 2, lines 16 to 18 of U.S. Patent 2,618,573). Hence, the ther-motransfer sheet in the following' example Wll largely be a pressure sensitive paper in nature provided that the material employed be highly transparent to infra-red radiation and sufliciently low in thermal conductivity.

3-1'Transfer sheet.-Equal parts of 1.5%, 3,3-bis (4- dimethylaminophenyl) 6 dimethylaminophthalide (prepared according to U.S. Patent Re. 23,024 of C. S. Adams) and 1.5% benzoyl or substituted benzoyl leuco methylene blue in chlorinated biphenyl (Aroclor 1242) and 20% casein solution are emulsied in a homogenizer until the oil droplets are about microns. A sheet of paper is coated to a thickness of about one mil with this emulsion and dried on Va smooth surface. Instead of chlorinated, biphenyl, chlorinated naphthalene, dialkyl adipate, diakyl sebacate, paraffin oil and peanut oil may be used.

3-2 Receiving sheet.-The slurry of one volume of kaolinite and 1.5 volumes of 20% casein solution is coated to a thickness of about one-half mil on a sheet of paper and cast dried. The copy pattern will be blue or green.

Example 4 In Example 3 two coloring materials 3,3 bis (4-diphenyl.

4-2 Receiving sheet-The sheet of Example 3-2 is coated with aqueous solution 15 to 20% phosphotungstic acid, phosphomolybdic acid or phosphtungstomolybdic acid. To coat with this solution on a paper without claylike material also shows good results.

Example 5 In this example even heteropoly acids or their mixture a-re not necessary, for a new class of coloring materials of acyl hydrazine type has been discovered. These new colorless materials, which are actually a substantially colorless derivative of an auramine form a permanent blue-purple pigment at once on contact With certain acidic inorganic substances, and have the following general formula:

wherein R=alkyl, aromatic, substituted aromatic, heterocyclic monovalent radicals, substituted heterocyclic.

5-1 Transfer sheet.-One part of 1% 1-[bis(4,4dimethylaminophenyl)methyl] 2 isonicotinoyl hydrazine, having formula below:

in dibutyl adipate and 4.5 parts of 15% animal gelation Y solution are emulsified and coated according to the procmethylaminophenyl)-6-dimethylaminophthalide and benf zoyl leuco methylene blue are used to make the thermoresponsive coloring material on the transfer sheet. The rst one turns blue at once upon contact with the receiving sheet, which carries a claylike material, and the color soon fades away. The second one gradually develops a permanent `green-blue color on clay. It is a pleasant surprise to find that the colorless 3,3 bis (4-dimethylaminophenyl)-6-dimethylaminophthalide in certain organic solvents can be converted to a permanent bright intense blue pigment immediately by contacting heteropoly acids alone or their impregnation with an absorbent material. Thus, the second color material, benzoyl leuco methylene blue, is rendered unneccessary.

4-1 Transfer sheet- Same as 3-1 except that 1.5% 3,3 bis (.4 dimethylaminophenyl) 6 dimethylaminophthalide in dibutyl adipate replaces 1.5% 3,3 bis (4-dimethylaminophenyl) 6 dimethylaminophthalide 4and ess disclosed in U.S; Patent 2,712,507 by Green. This process produces gelatine microcapsules containing the thermoresponsive material. Instead of isonicotinoyl, the benzoyl or-butyryl analogs may be used.

5-'2 Receiving sheet.-Sheets of l-2 and 3-2 or ordinary paper with clay fillers may be used.

Example 6 The above tive examples are intended primarily to make one copy or a few copies with a single transfer sheet. The following example will demonstrate the making of a master plate from which many copies can be made on any conventional machine whether it is rotary or not. -In principle any copy may be used as a master plate in my process, as long as the copy contains hydrophobic-patterns on a hydrophilic surface. The following example is the most preferred embodiment at this time.

6-1 Transfer sheet.-One part of 10 to 20% iron stearate in diethyl adipate and 4 parts of 15 to 20% animal gelatine solution are emulsied according to the procedure of 2-1. Instead of iron stearate, silicone oil, parafiin oil or fatty acids may be used.

6-2 Receiving sheen- Sheet of 1-2 or 3-2 is `coated with a thin layer Vof Zinc acetate or sodium aluminum silicate.

The precise consistency of the compositions in the foregoing examples depends on the coating methodemployed. Some methods are applicable to high-viscosity materials, while others to medium or low-viscosity materials. One skilled in the art would have little or no diicultyin obtaining the proper consistency for the coating methodv chosen, merely by adjusting the amount of water in the coating composition. v

It should be understood thatr the novelty of my thermotransfer process and material isnot necessarily dependent on` theprocedure. of making-transfer sheets. kSome of these preparative processes are well known in the arts, for example, as disclosed in U.S. Patent 2,183,053 of Taylor and U.S. Patent 2,550,466 and 2,712,507 of Green.

The duplicating materials may be varied considerably as to the amounts of the ingredients and as to the kinds of the ingredients and the supports as long as the resulting copying sheets have sufficiently low thermal conductivity and effective infra-red transparency. Any skilled artisan with a thorough understanding of my thermotransfer process would have no difficulty in producing an equivalent `copying sheet to suit the process or in adjusting a coating composition to the proper consistency.

The copy material has been described in great detail in the form of examples above. The structure and application of such material in the operation of my novel thermotransfer duplicating system, will be illustrated by description in connection with the attached drawings to which the reference is made.

For clarity all the figures present exaggeratedly enlarged cross-section views. While other physical structures of the duplicating sheets and other combinations of the superimposed relations between the original and duplicating sheets are possible, the following figures demonstrate only the more preferred embodiments.

Figures 1 to 6 show the structures of the printed page, transfer sheet and receiving sheet. Figures 7 to 8 show the application of the transfer and receiving sheets in my thermotransfer `duplicating system.

Figure 1 shows the printed page P having characters or drawings 1 'on the support 2, l-l being a two-sided and 1 2 a one-sided printed page.

Figure 2 shows a transfer sheet T having a support 4 bearing a transfer coating 3.

Figure 3 shows a receiving sheet R comprising a support 6 carrying a receiving coating 5. The support 6 may be either transparent or opaque.

4In Figure 4 are shown three types of the transfer coating 3: in 4-1 the coating is substantially a monolayer of the individual microparticles 7 containing a thermoresponsive material. ln 4-2 the coating has micro-inclusions of a thermoresponsive fluid 8 in a continuons film of the hydrophilic colloid binders; and in 4-3 the coating is made of a material to be thermotransferred incorporated with the waxes 9.

In Figure are shown three types of individual microparticles 7: in 5-1 the microparticle may be hydrophilic colloidal spherical shell 10 containing a material to be thermotransferred in organic solvents 11; in 5-2 the hydrophilic colloid microsphere 10 contains a material to be thermotransferred with waxes 9; and in 5-3 the microsphere is made of a material to be thermotransferred and waxes 9.

It will be appreciated that the microparticles in Examples 1, 2, 5 and 6 need not be all spherical, but may be composed of a mixture of many different shapes. Thus, the microspheres shown in Figure 4-1 and Figure 5 are for illustration only.

In Figure 6 are shown three types of the receiving coating 5: in 6-1 the coating is made of material having properties of absorption and adsorption 13 with the binders ,12; in 6-2 the coating has absorbing and adsorbing material 13, the binders 12 and the color formers 14; in .'Figure 6-3 the coating has the binders 12 and compounds characterized by the absorbing and adsorbing property 13 in which the color formers 14 are impregnated.

Figure 7 shows that the two-sided printed page P can be copied with a transfer sheet T and receiving sheet R in :two superimposed relations as in 7-1 and 7-2, after the heat is applied from the direction of the arrows.

Figure 8 `shows a one-sided printed page or drawing P rcan be copied in four more preferred positions as in 8-1, f8-2, 8 3, and 8-4. The heat is applied from the direction of the arrows while the heat may be applied from either side of the original. 15 is the facsimile and 16 is the re- 6 verse image. 16 may be a facsimile, if the support `is transparent as is the case in Figure 7-2, 8-2, and 8-4.

Whereas the source of heat is not shown in the drawing and is not a part of this invention, any commercial tungsten filament lamp mounted in a -quartz tube capable of producing high thermal intensity is suitable for my thermotransfer process.

From the foregoing description and the accompanying drawings, it will be seen in a more precise manner that a thermotransfer process for producing a permanent copy, in a single operation, directly from an original having reproducible portions comprises: (a) placing a transfer sheet and receiving sheet together as :a smooth face-toface two-ply combination, (b) positioning said original in thermoconductive contact with the two-ply combination, (c) strongly, brieiiy and uniformly directing sufcient intensity of a radiation rich in infra-red through the two-ply combination to provide the heat images of said reproducible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copying-surface of said receiving sheet, thereby producing visible images corresponding to the reproducible portion of said original, and (d) separating the copy from said original and said transfer sheet.

The original must have reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images well above the 1temperature of other portions of the original to effect a material transfer from one surface to another in close contact under conditions of irradiation.

=The transfer sheet comprises a thin exible sheet material of essentially uniform thickness carrying thermoresponsive material capable of being transferred, when heated, to a copying surface in close contact.

The receiving sheet comprises a thin flexible sheet material of essentially uniform thickness with a copying surface receptive to the thermoresponsive material. Both the transfer sheet and the receiving sheet are further characterized by being substantially colorless and must l be sufficiently transparent to infra-red radiation and sufliciently low in thermoconductivity.

MODIFICATION The duplicating process and material have been described fully and accurately; it is desired to record the modifications. While all the modification and equivalents are within the scope of this invention, the most important ones are the following:

One modification of this invention is that heteropoly acids in organic solvents maybe employed as the thermoresponsive material on the transfer sheet as well as on the receiving sheet.

Another modification is that the reactive components of diazotype may be treated in the same manner as mentioned in the above examples. That is, one reactive component may be on the transfer sheet, the other on the receiving sheet, or both reactive components on the transfer sheet with certain stabilizing agents to prevent premature reaction. Examples are p-diazomethylaniline zinc chloride, phloroglucinol, and 2,3 dihydroxynaphthalene.

Another modification is that the support of the transfer sheet may be made of a sponge-like material which contains the coloring fluid in its colorless form.

Still a further modification is to use cyanides of triphenylmethane dyes in the transfer sheet.. Examples are pararosaniline cyanide, crystal violet cyanide, malachite green cyanide, and ethyl green cyanide. In this case ordinary paper as well as specially treated paper may be used as receiving sheet, for the light will make the colorless cyanides assume color.

What is claimed is:

l. A thermotransfer process for producing a permanent copy, in a single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously genn 7 erating thereon corresponding heat images well above the temperature of other portions of the original to effect lamaterial transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, which comprises: (a) placing a transfer sheet thin and uniformly thick sheet material with a copyingvsurface receptive to Vsaid thermoresponsive material, both said sheets being further characterized by being substantially colorless, sufficiently transparent` to infra-red radiation and sufficiently low in therrnoconductivity to make the process operable, (b) positioning said original in therrnoconductive contact with said two-ply combination, (c) strongly, briefly and uniformly directing sufficient intensity of a radiation rich in infra-red through the twoply combination to provide the heat images of said reproducible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copying-surface of said receiving sheet, thereby producing visible images corresponding to the reproducible portions of said original, and (d) separating the copy from said original and said transfer sheet. Y

2. A thermotransfer process for producing a permanent copy, in a single operation, directly from an original having reproducible portions capable of converting radiant energy .to heat energy and of almost instantaneously generating thereon corresponding heat images: Well above the temperature of other potrions of the original so as to effect a material transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, which comprises: (a) placing a transfer sheet and a receiving sheet together as a smooth face-to-face two-ply combination, said transfer sheet comprising a thin Vflexible sheet material of substantially uniform thickness carrying at least one thermoresponsive organic waxy material capable of being transferred, when heated, to a copying-surface in close contact, said receiving sheet comprising a thin flexible sheet material of substantially uniform thickness with a copying-surface receptive to said thermoresponsive material, both said sheets being further chcaracterized by being substantially colorless, sufficiently transparent to infra-red radiation and suciently low in thermal conductivity to make the process operable, (b) positioning said original in thermoconductive contact with the two-ply combination, (c) strongly, briefly and uniformly directing sufficient intensity of a radiation rich in infra-red through the two-ply combination to provide the heat images of said reproducible por- Ytions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copyingsurface of said receiving sheet, thereby producing a visible change corresponding to the reproducible portions of said original, and (d) separating the copy from said original and said transfer sheet.

' 3. A thermotransfer process for producing a permanent copy, in a single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of the original to effect a material transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, which comprises: (a) placing `a transfer sheet and a receiving sheet together as a smooth face-to-face two-ply combination, said transfer sheet comprising a thin exible sheet material of substantially uniform thickness carrying at least one hydrophobic thermoresponsive organic ink-receptive material capable of being transferred, when heated, to a copying-surface in close contact, said receiving sheet comprising a thin flexible Vsheet material of substantially kuniform thickness with a Water-insoluble and hydrophilic copying surface receptive to said thermoresponsive material, both sheets being further characterized by being substantially colorless,

V,clucible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate tothe copying-surface of said receiving sheet, thereby producing a visible change corresponding to the reproducible portions of said original, and (d) separating the copy from said original and said transfer sheet.

4. The process of claim 1 in which the sheet material of the transfer sheet is substantially and visibly transparent and the thermoresponsive material contains a substantially colorless derivative of bis(4dimethylaminophenyl)methane capable of producing a distinct color in contact with a color developing agent.

5. The process of claim l in which the thermoresponsive material is contained in the discrete microcapsules of at least one organic hydrophilic colloid substance.

6. A thermotransfer process for producing a permanent facsimile copy, in a single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images Well above the temperature of other portions of the original to elfect a material transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, said process which comprises: (a) placing a transfer sheet and a receiving sheet thermoconductivity to make the process operable, (b)

positioning said original in thermoconductive contact With the two-ply combination, (c) strongly, briefly and uniformly directing sufficient intensity of a radiation rich in infrared through the two-ply combination to provide .the heat images of said reproducible portions which travel to said transfer sheet and cause said thermorsponsive material to migrate to the copying-surface of said receinving sheet, thereby producing a visible change corresponding to the reproducible portions of said original and (d) separating the copy from said original and transfer sheet.

7. The process of claim 6 in which the thermoresponsive organic material contains at least one colorproducing agent in its substantially colorless form capable of rapidly forminga distinct color on eective contact with a color former.

8. A thermotransfer process for producing a permanent facsimilie copy, in .a single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of thev original to effect a material transfer from one surface to another in close Contact under conditions of irradiation, as hereinafter provided, said process which ecartees comprises: (a) placing a. transfer sheet and a receiving sheet together as a smooth face-to-face two-ply combination, said transfer sheet comprising a thin flexible sheet material of essentially uniform thickness coated with a composition consisting essentially of a nlm-forming material and at least one thermoresponsive organic material capable of being transferred, when heated, to a copying surface in close contact, said thermoresponsive organic material containing at least one substantially colorless derivative of a dyestuif capable of producing almost instantaneously a distinct color on suicient contact with an acidic substance, said receiving sheet comprising a thin flexible sheet material of essentially uniform thickness with a copying-surface receptive to said thermoresponsive material, both said sheets being further characterized by being substantially colorless, sufficiently transparent to infra-red radiation and sufficiently W in thermoconductivity to make the process operable, (b) positioning said orignal in thermoconductive contact with the two-ply combination, (c) strongly, briefly and uniformly directing sufficient intensity of a radiation rich in infrared through the two-ply combination to provide the heat images of said reproducible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copying-surface of said receiving sheet, thereby producing a visible change corresponding to the reproducible portions of said original, and (d) separating the copy from said original and transfer sheet.

9. The process of claim 8 in which the dyestuff is se- Vlected from the group consisting of an auramine, a triphenylmethane and a methylene blue. 10. The process of claim 6 in which the thermoresponsive organic material contains a substantially colorless cyanide `of a triphenylmethane dye.

11. The process of claim 6 in which the thermoresponsive organic material contains diazo compounds.

12. A thermotransfer process for producing a permanent facsimile copy, in a single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of the original so as to effect a material transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, which comprises:-

(a) placing a transfer sheet and a receiving sheet together as a smooth face-to-face two-ply combination, said transfer sheet comprising a thin flexible sheet material of essentially uniform thickness with a coating consisting of a continuous phase and a discontinuous phase, the discontinuous phase of the coating comprising a plurality of discrete microparticles containing therein thermoresponsive color-producing organic material capable of producing a distinct color instantaneously on suicient contact with a color former and capable of being transferred, when heated, to a copying surface in close contact, the continuous phase of the coating being essentially a lm of a binding material, said receiving sheet comprising a thin eXible sheet material of essentially uniform thickness with a copying-surface receptive to said thermoresponsive material, both said sheets being further characterized by being substantially colorless, suciently transparent to infra-red radiation and suflciently low in thermal conductivity to make the process operable, (b) positioning said original in thermoconductive contact Vwith the two-ply combination, (c) strongly, briefly and uniformly directing suflicient intensity of a radiation rich in infra-red through the two-ply combination to provide the heat images of said reproducible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copying-surface of said receiving sheet, thereby producing a visible change corresponding to the reproducible portions of said origilo nal, and (d) 'separating the copy from said original :intl transfer sheet. t

13. The process of claim 12 in which the color-producing material contains a substantially colorless derivative of a dyestuif capable of producing a distinct color on suicient contact with an acidic substance.

14. A thermotransfer process for producing a permanent facsimile copy, in a single operation, directly from Ian original having reproducible portions capable of converting radiant energy to heat energy `and of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of the original so .as to effect a material transfer from one surface to another in close contact under conditions of irradiation, as hereinafter provided, which comprises: (a) placing la transfer sheet and a receiving sheet together `as la smooth face-to-face two-ply combination, said` transfer sheet comprising ra thin flexible sheet materialV of essentially uniform thickness coated with a film-form-` ing agent, having entrapped therein a plurality of discrete` yorganic liquid micro-droplets capable of being transferred, when heated, to a copying-surface in close contact, said receiving sheet comprising ya thin flexible sheet m-aterial of essentially uniform thickness with a copying-surface receptive to said thermoresponsive material, bot-l1 said sheet-s being further-characterized by being substantially colorless, suiiciently transparent to infrared radiation and sufficiently low in thermal conductivity to make the process operable, (b) positioning said original in thermoconductive contact with the two-ply combination (c) strongly, briefly and uniformly directing sucient intensity Iof a radiation rich in infra-red through ,-the two-ply combination to provide the heat images of said reproducible portions which travel to said transfer sheet and cause said thermoresponsive material to migrate to the copying-surface of said receiving sheet, thereby producing -a visible change corresponding to the reproducible portions of said original, and (d) separating the copy from said original and said transfer sheet.

15. The process of claim 14 in Which the liquid microdroplets contain a colorless derivative of a dyestuif capable of producing a distinct color on. sufcient contact with an lacidic substance.

16. A thermotransfer process for producing a perm-anent copy, in la single operation, directly from an original having reproducible portions capable of converting radiant energy to heat energy rand of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of the original, to effect `a .material transfer from one surface to an :other in close contact under conditions ofI irradiation, as. hereinafter provided, which comprises: (a) placing a4 transfer sheet `'and 'a receiving sheet together as a smooth-tA face-to-face two-ply combination, said transfer sheeti comprising a thin flexible sheet mate-rial of essentiallyv uniform thickness carrying a sponge-like material containing at least one thermoresponsive organic material' capable of being transferred, when heated, to a copying; surface in close contact, said receiving sheet comprising;

a paper with a copying surface receptive to said thermo responsive material, both said sheets being further char-- acterized by being substantially colorless, sufficiently transparent to infra-red radiation and 4sufficiently low im thermoconductivity to make the process operable, (b)1 positioning said original in thermoconductive Contact with the two-ply combination, (c) strongly, briefly and uniformly directing 4sufficient intensity of a radiation rich in infra-red through the two-ply combination to provide the heat-images of said reproducible portions which travel to said transfer sheet and causes said thermoresponsive material to migrate to the copying surface of said receiving sheet, thereby producing visible images corresponding to the reproducible portions of 1`1 said original, and (d) lseparating the copy from said original and said transfer sheet.

17. A thermotransferprocess for producing permanent duplication copies directly from `a graphic original having highly infra-red iabsorptive patterns capable of converting radiant energy to Iheat energy and of almost instantaneously generating thereon corresponding heat images Well above the temperature of other portions of the original t effect amaterial transfer from one surface to another in close contact under conditions of irradiation; said original being positioned in a contact superimposed relation to a transfer sheet and a receiving member which are next to each other and sufficiently less infra-red absorptive so that the heat patterns are selective; said transfer sheet being a diexible iiately-ing sheet material of essentially uniform thickness comprising a flexible, dimensionally stable base sheet and on at least one side a heat responsive coating containing at least one itself-stable coloring material in its substantially colorless form carried in at least one organic hydrophobic inert substance wihich is uniformly distributed in at least one organic barrier; said receiving member having a support carrying a non-transferable hydrophilic coating containing at least one solid acidic color former capable of producing a distinct color 'on sufiicient heat contact with the coloring material of said transfer sheet; on irradiation of said original, as hereinafter provided, infrared absorptive patterns :absorbing the radiation and converting it to heat which travels to the transfer sheet by conduction and causes rupture of the barrier around the coloring material according to the patterns to be copied, the coloring material thu-s being released in the liquid state and transferred to said receiving member wherein the coloring material and the color former are brought together in suicient heat contact, thereby distinct and permanent colo-r images of said original being produced; said process which comprises: (a) positioning said transfer sheet land receiving member in face-to-face Contact and then in contact-superimposed relation with said graphic original, (b) briefly exposing said original to an intense and uniform light rich in infra-red radiation through said transfer sheet and said receiving member, the exposure being sufficient to cause the coloring material in said transfer sheet to contact the color former in said receiving member according to said patterns of the graphic original, and (c) separating the receiving member from said transfer sheet and said original.

18. A thermotransfer process for producing permanent facsimile duplication copies directly from a printed page having highly infra-red absorptive patterns capable of converting radiant energy to heat energy and of almost instantaneously generating thereon corresponding heat images well above the temperature of other portions of the original to effect `a material transfer from one surface to another in close contact under conditions of i1'- radiation; said original being positioned in a contact superimposed relation to a transfer sheet and a receiving sheet which are next to each other and suiciently less infra-red absorptive so that the heat patterns are selective; said transfer sheet being a flexible flat-lying sheet material of essentially uniform thickness comprising a iiexible, dimensionally stable base sheet and on at least one side a heat responsive coating containing at least one itself-stable coloring material in its substantially colorless form carried in at least one organic hydrophobic inert substance which is uniformly distributed in at least one organic barrier; said receiving sheet having a support carrying a non-transferrable hydrophilic coating containing at least one solid acidic color former capable of producing a distinct color on sufficient heat contact with the coloring material of said transfer sheet; both sheets being further characterized by having sufficiently low thermal'conductivity; on irradiation ofsaid original,

as hereinafter provided, infra-red Vabsorptive,patterns absorbing'the radiation and converting it to heat which .travels to the transfer sheet by conduction and cau-ses rupture of the barrier around the coloring material according to the patterns to be copied,'the coloring material thus being'released in the liquid state and transferred to said receiving sheet wherein the coloring material and the color former are brought together in sutiicient heat Contact, a ydistinct and permanent color image of said original thereby being produced;v said process which comprises: (a) positioning said transfer sheet and receiving sheet in face-to-face contact and then in contact-superimposed relation with said graphic original, v(b) briefly exposing said original to an intense and uniform light rich in infra-redradiation throughsaid transfer'sheet and receiving sheet, the exposure being sucient to causethe coloring material in said transfer sheet' to Contact the color former in said receiving sheet according t0A said patterns of the graphic original, and (c) separating the receiving sheet from said transfer sheet and said original.

=19. The process of claim 18 in which the coloring material contains a substantially colorless derivative of a dyestuif and the support of the receiving sheet is a paper.

20. The process as defined in claim 18 in which fthe organic barrier is selected from a group consisting of starch, casein, wax, and yanimal gelatine.

21. The process as defined in claim 18 in which the coloring material is 3,3 bis (4-dimethylaminophenyl)-6-v dimethylaminophthalide and the color former is selected from a group consisting of phosphotungstic acid, phosphomolybdic acid and phosphotungstomolybdic acid.

22. The process as dened in claim 18 in which the coloring materialis a leucohydrazine dye andthe color former is a claylike material in major portion.

References Cited in the tile of this patent UNITED STATES PATENTS 798,528 ostwald Aug. 29, 1905 1,514,222 Murray Nov. 4, 1924 1,781,902 Gill Nov. 18, 1930 1,871,683 Gaskins Aug. 16, 1932 1,923,625 Jackson Aug. 22, 1933 2,254,483 HessV et al. Sept. 2, 1941 2,304,890 Dickey et al. Dec. 15, 1942 2,347,022 Austin Apr. 18, 1944 2,458,328 Adams Ian. 4, 1949 2,548,366 Green Apr. 10, 1951 2,582,932 Lustboder Jan. l5, 1.952 2,634,677 Klimkowski et al. Apr. 14, 1953 2,653,110 Zimmerman Sept. 22, 1953 2,654,673 Steinhardt Oct. 6, 1953 2,663,579 Zimmerman Dec. 22, 1953 2,663,656 Miller Dec. 22, 1953 2,713,822 Newman July 26, 1955 2,730,456 Green et al. Ian. 10, 1956 2,753,353 Bernstein et al. July 3, 1956 2,755,200 Balon July 17, 1956 2,763,659 Archer Sept. 18, 1956 2,764,085 Shoemaker et al Sept. 25, 1956 2,769,391 Roshkind Nov. 6, 1956 2,800,457 Green et a1. Jury 23, 1957 2,808,777 Roshkind Oct. 8, 195,7

FOREIGN PATENTS 516,137 Canada Aug. 30, 1955 OTHER REFERENCES UNITED STATES PATENT :oEEIcE CERTIFICATE 0F CORRECTION Patent No.. 2,939,009 May 3l, 1960 Jack NL. Tien It is hereby certified that error appears in the above numbered patent requiring correction and that the sa id Letters 4Patent should read as corrected below.

Column l2, lines 35 and 36, for "is a leucohydrazine dye and the color former is a claylike material in major portion" read contains a substantially colorless derivative of an auramine Signed and sealed this 22nd day of December 1964,.

.(sEAL) Attest .W. VSWIDER EDWARD J. `BRENNER Altteisting Officer Commissioner of Patents

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