DE2907529A1 - Image transfer system based on colourless basic solvent dyes - mixed with a wax or resin binder, which develop colours in contact with an acid or reducing developer - Google Patents

Abstract

Colour developer system for image transfer units consists of (a) a colourless solvent dye which is a free base of a basic dye e.g. of the diphenylmethane, triphenylmethane, triarylmethane, xanthene, azo or phenazine type, which develops a colour on reaction and/or contact with an acidic and/or reducing developing agent, and (b) a wax or resin binder which does not develop the dye base, in (c) a non-developing solvent. After mixing, the solvent may be removed e.g. by spray drying to give particulate prod. The binder resins used may be e.g. acrylic, polystyrene, ethylcellulose, chlorinated rubber, saturated polyesters, co- and terpolymers of PVC, PVA, vinyl toluene, butadiene, acrylonitrile, etc. The compsns. have a wide range of application in image transfer units which are activated by imagewise application of pressure, heat, light or electrical discharge to cause contact of the colourless basic dye with the developing agent which is e.g. an organic acid, natural or synthetic tannin, etc. Typical application for the compsns. are in carbon paper, overhead projector transparencies, etc.

Description

PATENT LAWYERS

J. REITSTÖTTER W. KINZEBACH

PROF. DR. DR. DIPL .. ING. DR. PIIIU DIPL. CHBM.

W. BUNTE (ΐ938-ΐθ7β) K. P. HÖLLER

DR. INO. DR. RER. ΝΛΤ. DIPL. CHBM.

TBLEFONi (OSO) 37 63 83 TELBXl 5215208 ISAR D

BAOERSTRASSB 22, 8000 MUNICH

Munich, February 26, 1979 M / 20 035 M / 20 062

INCA LIMITED

28-34 Dundas Street, Christchurch,
New Zealand

Color development composition for an image transmission system and their application

POSTAL ADDRESS! POST BOX 780, D-8000 MUNICH 43

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The present invention is applicable to the field of image development of images. It is suitable for Use under pressure, for example in the case of carbonless copy paper "for use under heat" for example in thermal image transmission systems and for the selective, imagewise application of electrical discharges.

Various are known in the field of image transmission Color precursors used, which are colorless or essentially colorless compounds and a Color reaction result when they come into contact with an acidic electron acceptor material, for example attapulgite, Bentonite, benzoic acid and similar materials brought will. These materials have been used to make colorless carbonless sheets or "carbon papers" and carbon paper forms for business purposes to manufacture thermally activated papers and various photographic systems. Although many of these dye precursor image transfer elements have been found to be commercially viable, they nevertheless suffer from several disadvantages, from to which the following are to be mentioned:

1.Precursors that rapidly develop in color also tend to fade quickly.

2. Fade-resistant color precursors only lead to very long

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More color development and are also costly.

3. Such color precursors are difficult to resolve and require expensive solvents.

4 · The color range is limited.

The present invention relates to compounds, compositions, Coatings, solutions, dispersions, devices and processes applicable to image transfer systems which are essentially one as a developable element in a color developing composition Use colorless soluble dye. As used herein, "soluble dye in colorless form" relates to the free base of a dye base, in contrast to dyes »which have been used up to now and which are bases acts, which by adding leuco, carbinol, styryl, cyanide, benzopyran or other organic Groups that convert a usually colored color base into colorless materials have been chemically modified. Examples of soluble dyes which can be used in accordance with the invention in colorless form are those of the two are the free bases of color bases, including diphenylmethane, triphenylmethane, triarylmethanes, xanthenes and azo dyes and also around the free bases of phenazine dyes. These dyes are characterized in that they generally only have one in most media have low solubility, but are readily soluble in fatty acids.

The color developing composition of the present invention comprises

a) an essentially colorless soluble dye, which term is used in connection with the preceding Definition must be seen when responding with a

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_ • _

ίυ

Developer, selected from acidic and reducing compounds, leads to color development, and

b) a binder or binders selected from wax and resin binders, which are not lead to the development of the soluble dye base, the binder with the soluble dye in the presence of a non-developing solvent was mixed. The non-developing solvent can be used in some forms of the composition are removed or have already been removed, for example by Spray drying.

The composition of the invention can take various forms accept. In one form is the color developing composition particulate and is in combination with a carrier that is a resin dispersion or a resin solution in which the composition is practically insoluble. In a different form does the color developing composition cover a substrate? for example a sheet or film material which, in contact therewith, contains a developer for the essentially colorless, Contains soluble dye. Usually, the developer is applied as a coating on a substrate, which superimposed in use with the substrate to which the color developing composition is applied is so that by selective electrical discharge, by applying pressure, heat or the like, the required Developmental reaction can take place. However, in some forms it is also possible to use the color developing composition in particulate form in a carrier, the carrier also being a developer for the soluble dye in colorless form. In this embodiment of the invention it is desirable »

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that the binder of the color developing composition is essentially insoluble in the vehicle. In other embodiments of the invention can include microencapsulated developers or solvents for the developer so that when breaking or tearing the required Movement of the developer and the substantially colorless dye towards each other takes place.

The most convenient form of developers are organic acids, which are essentially non-crystalline and do not sublime at normal room temperatures. Such developers are appropriately selected among natural and synthetic tannins »

The invention thus encompasses applications, methods of manufacturing the products and the products as such, be it in the form of compounds, compositions, sheet or film materials. Examples include carbonless copy paper, Slides for projectors and the like »

Some preferred embodiments of the invention are explained with reference to the drawings, in which:

Fig. 1 is a schematic flow diagram illustrating two manufacturing methods,

Figure 2 illustrates a two-ply thermographic image transfer element;

Figure 3 shows a single layer thermographic image transfer element represents

Figure 4 shows a transfer pressure sensitive copy element means,

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Fig. 5 shows an alternative pressure-sensitive, two-ply Represents copy element,

Pig. 6 denotes another two-ply pressure-sensitive copier element, and

Fig. 7 represents a further variation »

Virtually all published work on the use of color precursors in the various forms of copying use leukocyanides, lactams, and benzpyrans like that. The main problem with these materials, at least in terms of making a permanent one Bilds shows that these reactions are reversible. Although various possibilities are therefore known are to convert the dye from the colorless to the colored form, it seems impossible to change the reversible form Interrupt reaction. For example, Harris »Kaminsky & Simard have the following mechanism for the reversible Proposed reaction of malachite green cyanide:

/ \ - C ⁺ + CN "> (VC-OH

\ / / Hydrolysis \ / /

(CH ₃ ) ₂ N

colorless

colored

colorless

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A solution to the above problem was provided by the National Cash register by using benzole ecomethylene blue, which develops its color through gradual oxidation »However this reaction takes several months and must therefore be combined with one of the aforementioned intermediates Precursors are applied. In addition, this is System limited to a blue shade if a permanent color is required.

Against this background, the finding was of interest » that a certain group of soluble dyes dissolve in very small amounts in certain solvents, and in an amount that usually leads to a classification as "only slightly soluble". However, this resulted Small amount does not color the solvent, but a very strong color when you see the solution on paper poured.

The definition of the term "soluble dye" can be found in the Color Index, 2nd edition 1956 »Volume 2 on the pages 2815 ff · The acid forms of certain acidic dyes do not work with the present invention and are otherwise of no interest (although Ciba-Geigy these dyes are the subject of the two GB-PSs '1 307 382 and 1 317 411). The dyes used in the present invention are the base forms certain color bases. These dyes are characterized by a partial solubility in glycols and Fatty acids and only a very low solubility in aromatic and aliphatic solvents and oils. Examples these dyes are Cl Solvent Green 1 & 2 Cl 42000 B; Cl Violet 8-42535B; Cl Violet 9-42555 B; Cl Red 49-45170 B; Cl Solvent Orange 3-11270 B; Cl Solvent Yellow 34 - Cl 41000 B.

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These dyes have been used to make typewriter tape and carbon papers for many years. So far, however, they have always been in glycols, oleic acid, Carnauba wax, and the like, dissolved.

According to the plague that these dyes possibly could be used in colorless form, a first attempt led to a pressure-sensitive sheet material for copying purposes using the following procedure;

Halowax 1000 solvent

(chlorinated naphthalene) 20 g

Color base Rhodamine-Base FB 0.5 g

Paraffin wax binder 79.5 g

The rhodamine base FB is dissolved in the Halowax 1000, the is again added to the melted paraffin wax. This is then applied to paper that was previously used with an underlayer of gum arabic was provided. The main purpose of the gum arabic underlayer is to prevent that the Halowax 1000 and the ehodamine base react with the paper during the coating operation.

Chlorinated biphenyls, Paraffin oils »Phthalate esters and acid-free vegetable oils with Used success.

As for the binders, the paraffin wax has been made successful by polythene, polybutene, polyisobutene and their wax mixtures, as well as microcrystalline waxes and geresin waxes replaced.

Although each of the aforementioned sheets proved its suitability, to transfer a colorless coating, which when

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Contact with an acidic paper to develop color led »the gum arabic coating resulted in a paper that tossed with changes in humidity. Other water soluble Resins, for example polyethylene oxide, hydroxyethyl cellulose » and the like, have also been tried, however none of these materials was as good a barrier as gum arabic *

Another problem in this connection was to _see are that chlorinated biphenyls and naphthalenes as seriously polluting. It was therefore rethought and the requirements to be placed on the solvents were subjected to a closer examination. It was finally determined that the solvent requirement was that only solvents with weak hydrogen bonds, known to those skilled in the art of resin formulation as class 1 solvents, were considered. These include aromatic, aliphatic, chlorinated solvents and nitro-hydrocarbon solvents.

In order to keep the dye in colorless form, this should be the case Binder or resin contain no free acid groups or polar groups and also in the solvents class 1 soluble. This group includes acrylic, polystyrene, ethyl cellulose, EHEC, chlorinated rubber and Rubber hydrochlorides, saturated polyesters and copolymers and terpolymers of PVC, PVA, vinyl toluene, butadiene, Acrylonitrile and the like. Because of the clarity, the low cost price and the wide range of solubility Acrylic, polystyrene and their copolymers are to be regarded as preferred resins.

After it was established according to the invention that the color

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substances in a wide range of resins could be obtained in a colorless state, next became the investigated thermally activated systems. For this purpose, the following formulation was tried out first:

Toluene 40 g

Vinalak 5911 (polymethyl / butyl acrylate) 6.4 g

or Tyril 867 (styrene-acrylic resin) or Paraloid B 72.

The following soluble dyes were added to produce different colors:

1 / o

1 fo

1 fi

ι io

1.4 1 " 0.8 ^ 0.8 io

Of course, other colorations can also be achieved by simply mixing colors, albeit for a thermal one Application the Mgrosinbase can not be used, because this dye is strong in the infrared area Has absorption and thus would lead to faulty images.

The dyes are simply added to the toluene / vinalak mixture stirred in. Within half an hour, the dye has dissolved to form a pale solution. These Solution can be applied to a transparent film, for example cellulose acetate or polyethylene

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Red: Ehodammbase blue: Viktoriablaubase dark blue: Malachite green base Rhodamine base green: Malachite green base black: Rhodamine base Malachite green base Auramine base celb: Auramine base

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terephthalate. Here you can have a thickness of approximately Select 0.0025 mm (0.0001 ") (not critical). The dried film is colorless or almost colorless, depending on the choice of resin or the percentage content of the used Dyes. It is obvious that the amount of dye used depends on the type of solvent and / or the resin can be varied, preferably it is between 1 to 80 ^, particularly expedient between 10 and 30 wt .- ^ of the total solids of the composition = Some resins also result in a slightly stronger background staining, which in certain cases can be undesirable.

In order to develop an image on this film, a second film is coated with an acidic, reducing compound. An essential property of the acidic coating is that it should preferably melt, sublime or decompose ^{at a temperature between 50 °} C. and 400 ^{° C.} In addition, the acidic reducing compound should be compatible with the resin or be able to penetrate the resin used to dissolve the dye.

Various sublimable compounds have been found in connection with this two-blade procedure examined. The following connections have been tested with success:

Oxalic acid benzoic acid pyrogallol malic acid acetic acid

α-naphthol ß-naphthol thiourea

Since some of these materials are not to be regarded as acids, it follows that the color development on a re-

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induction reaction is based. The choice of acidic / reducing agent depends on the temperature used to induce of an image is required. For example, to print an image on a typical commercial thermal copier produce, oxalic acid, benzoic acid and salicylic acid are suitable. A small amount of resin is added so that the acidic / reducing agents adheres better to the substrate.

A typical formulation is as follows:

Ethanol 80 g

Polyvinyl butyral resin 4g salicylic acid 12g.

Drying this coating is important and must be done quickly to avoid the growth of large crystals which would affect the sharpness of the picture.

In order to develop a thermal slide or transparency in the form of a single sheet, non-sublimating acidic / reducing substances investigated. It is essential to use non-sublimable materials since the sublimation would lead to a premature development of the transparency. The following materials have been studied and proven to be useful:

Colophony oleic acid

Tannic acid succinic acid

Citric acid tartaric acid

Sorbic acid ascorbic acid

The following materials did not result in an image: Phosphoric acid hydrochloric acid

Below is an example of a thermal transparency

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tiild described in the form of a single leaf:

Colorless dye coating:

Acryloid B72 6g

Toluene 40 g

Ehodamine base 0.5g

The Acryloid B72 is dissolved in toluene at 50 ⁰ C and dissolves the Ehodaminbase in the resin solution. Then the solution is applied as a coating on polyethylene terephthalate film? giving a dry coating thickness of 0.0025 mm (0.0001 "). An acidic / reducing coating is then made:

Ethanol 80 g

Ethyl cellulose N200 10 g

Tannic acid 10 g

This solution is applied to the colorless dye coating, leaving a dry coating thickness of 0.0025 mm (0.0001 "). Exposing the above sheet to a black original in a thermal copier leads to a red image.

It is important that the solvent for the acidic / reducing coating is not a solvent for the resin in the coating with the colorless dye, otherwise a color development during the coating process entry.

The disadvantage of the above coating is that it is hot Ethyl cellulose is a thermoplastic resin. This can cause the coating to melt onto the original. Eventually the tannic acid reacts with the

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Ethyl cellulose and converts it into a thermosetting resin. However, to speed up this process, one can Use phosphoric acid, which reacts with the ethyl cellulose, but does not result in an image. Other resins that can be used are:

ClP polyvinyl butyral

CAB P.V.P.

PVP / VA U / i ¹

Urea melamine polyamide

Nylon polyurethane polyamide / epoxy resin

Also for this coating were water soluble and dispersible Resins examined with success, for example:

Hydroxyethyl cellulose PYP

Polyurethane dispersions
PVA dispersion
Polystyrene dispersions
Acrylic dispersions.

Preferred dispersions are the polyurethane and acrylic dispersions .

In all of the work described above, the following essential or necessary results have been found in accordance with the invention Characteristics:

Dyes as defined

Solvent as defined, i.e. preferably non-polar and without free acid groups

Resin or binder as defined, ie ,, preferably
not polar and without free acid groups.

The choice of an acidic reducing agent or reducing agent is not critical and depends on the eventual one

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Use or that required to evoke an image Temperature. However, it is assumed that the system described is different from all the systems described so far the greatest choice in terms of acidic reducing agents or reducing agents is offered by ο

The next goal was to make a carbon-free copier paper. Earlier attempts to produce it were unsuccessful in terms of storage stability because the resins used were sensitive to moisture and the moisture gradually developed the dye. Since the transparencies or slides were completely resistant to water, it was believed that using their coating composition could solve the above problem. However, if you put forward the standard Transparent image solution on bank paper (bank paper), the acidity of the paper led directly to the development of the dye. The paper provided with an underlayer of Alcostat and gum arabic (applied from water solutions) was then examined. This successfully prevented the dye from reacting, but left some background color and an additional one. Coating. In an attempt to develop pressure-sensitive and thermally-sensitive copier paper, a copy sheet with a front coated colorless dye / acrylic and a back coated solvent and acid mixture was examined next. This overcomes the problems of encapsulating a water-sensitive dye mixture. However, it was found necessary to introduce a third coating. It has therefore been sought to develop such a paper which does not require an extra coating. Because the transparency coating by the water or by alcohol in no way

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is attacked, spray drying became the standard transparent image formulation examined. One such standard transparent image formulation (standard transparency formula) includes, for example, the following components:

Styron P.S. 3 (polystyrene resin) 6 g Rhodamine Base F.B. 0.8 g

Toluene 40 g.

It was predicted that the spray dried powder should be almost colorless and ready to be mixed with one Water-based resin or an alcohol-soluble resin should be suitable for the coating. Then it was assumed that the acidic or reducing compound can be mixed into the same coating, whereby the sheet is made thermally active. For pressure-sensitive Scrolling it is only necessary that on the coated Backside a solvent (which dissolves the acid) is encapsulated. To make such a Paper became a thermally active and pressure sensitive coating composition of the just exemplified Kind of freeze-dried. This was achieved by placing the solution in a spray gun and placing it in sprayed in a stream of warm air.

The resulting powdery residue was collected. Alternatively, you can put the solution in an evaporation dish dry and chop and grind to a small particle size. That obtained by one of the two methods fine powder is very faint pink in color.

Then the obtained powder was mixed with water and a water-soluble or dispersible resin. That Freeze-dried material can, for example, with ir-

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such as a natural gum ("for example gum arabic) , with gelatin, cellulose resins (" for example CMC, methyl cellulose and the like), with polyvinyl alcohol, polyvinyl acetate and acrylic dispersions. A small amount of film material was added to maintain whiteness and to make paper that could be written on in a conventional manner. Thereafter, a reducing compound or a reducing acidic compound was added to the mixture; then it was applied to the paper. For example, the following was

Composition examined:

Styron / rhodamine base in powder form 50 g

Water 70 g

Acrylic dispersion / or polyox 10 g

Benzoic acid 5 g

Calcium carbonate (white filler) 10 g.

When this mixture was coated on the paper and dried, the paper was localized to approximate Heated at 12O ° C. Wherever heat is applied the paper turned red. In addition, a red color was formed wherever a solvent, such as toluene, MIBK, MEK, xylene, and the like are used became.

Alternatively, an alcohol-soluble resin can be used, for example polyamides, cellulose butyrates and cellulose propionates, and the like, polyvinyl butyrates, pyrollidones and the like, as well as polyurethanes. It's on the Hand that the choice of the carrier resin depends on the intended application and therefore not critical is to be seen.

Therefore, in order to make a pressure sensitive sheet, must

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a solvent such as xylene, microencapsulated and based on a another sheet of paper can be applied as a coating. When the two copy sheets are placed face-to-face any pressure applied will destroy the capsules and release the solvent, whereby the acidic, reducing compound or the reducing compound and / or the colorless dye / the resin powder can be selectively mobilized. An image is created in these areas. The method of encapsulation water-insoluble materials is known.

Replacing the acrylic dispersion in the above example by a conductive resin, for example "Alcostat" (registered trademark of Allied Colloids), so can an image can be created by electrical discharge.

A single layer thermal transparency was then developed using selective temperature or changes in the developer's mobility, considerable attention has been paid to it.

The application of sublimable, aromatic organic Acids to develop various color precursors known from US Pat. No. 2,770,534. Though aromatic organic acids in a two-layer thermal transparency work, there are two main problems when used with single-ply transparencies. To the First, the acids are crystalline materials and crystallize in most coatings, creating semi-opaque coatings (which appear as transparencies can not be used). Second, aromatic acids have a tendency to sublime or decompose, which gradually leads to an undesirable, premature color reaction, as the coating with the dye

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The runner or the color base cannot be physically separated from the acidic reagent.

Uni solving the problem of crystallization suggests the U.S. Patent 3,594,208 suggest the use of a polymeric plasticizer to keep the acids in solution. For example it is stated that a resin plasticized internally with butyric acid has proven successful. Although this may lead to a reduction in the crystallization rate, this can only rarely result in the Crystallization can be completely prevented. In addition, this measure does not prevent it the sublimation of the acid and the subsequent premature color reaction.

US Pat. No. 3,669,747 attempts to prevent the premature color reaction by forming an adduct of the organic acid with an amine. Although this can prevent the premature color reaction, it does not prevent the developer _{or the like from crystallizing}

U.S. Patents 3,914,510 and 3,965,282 describe attempts to Use acidic reagents that have a lower tendency to sublimation and crystallization exhibit. Although the use of sulfonic acids or phthalic acids reduces the rate of crystallization or the May decrease sublimation capacity, both phenomena still occur, which limits the shelf life »

The aforementioned patent specifications can be seen " that premature color formation and crystallization of the acidic developer and / or the occurrence of background coloration in the development of single-layer or one-piece

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thermal transparencies pose major problems.

Therefore a group of organic acids had to be found which are non-crystalline, do not sublime at normal temperatures, but ^{melt above 80 °} C.? sublimate or decompose.

As a result of research and experimentation with the various acids and acidic resins, it was found that a group of materials stood out. This group includes the natural and synthetic tannins. Tannins have the advantage that they are amorphous powders are stable at normal temperatures and react with soluble dyes above 80 ⁰ C.

When using the tannins as a developer, there were also other advantages. So add the tannins completely clear coatings which have no tendency to crystallize. You also get coatings that are very stable and have a low tendency to form background color development. Although the Last two results were as expected, it was also found that tannin developers too exceptionally sharp images and that, moreover, these images are only slight during storage Have a tendency to sublimation.

Before it was determined that tannins could be used, thermal transparencies with different, Sublimable Organic Aromatic Acids Developed «The sublimable developers led to the appearance of a very little "halo" effect around the picture surfaces, which

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whose sharpness has been reduced. In addition, the images so produced also have a tendency to sublime with the dye, and although the use of soluble ones Dyes it prevented that the dye was converted back into its colorless form, this could Property still have a disruptive effect if the transparencies are stored together or with other plastic films were »The subliming images were also able to pass through the paper and develop to perform on certain other films.

From a chemical point of view, the group of tannins is difficult to define. Tannic acid of natural origin is a complex of polyphenolic compounds, whereas synthetic tannins are produced by the condensation of sulfonic acids of higher hydrocarbons, phenols and cresols, with formaldehyde. Although synthetic tannins are classified as polyacid formaldehyde for the present purposes, their main distinguishing feature is that they render proteins insoluble. In order to create a useful definition, it proves useful to define suitable tannins as natural or synthetic products which can make proteins insoluble and which are either amorphous powders or have only a weak crystal structure and a melting range or decomposition range in the temperature range between 70 ⁰ G and 250 ⁰ C have.

Suitable materials include tannic acid, lignins, Corilagine _s catechins and the like, and also the following commercial products Printan G- (product of Ciba-Geigy), Mesitol BN, Mesitol GD and Mesitol GDN (products

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from Bayer), Taufix AL (product from Hoechst) and the like.

The tannins preferably make up between 5 and 75% by weight of the developer coating or matrix »

A schematic flow diagram illustrating the two methods of manufacture is shown in FIG. 1. The solvents (A), resins or binders (B) and Soluble dyes (C) are mixed in the desired proportions in a mixing device (D) until solution occurs is. At this point, the resulting solution can either be applied directly to a substrate as a coating or spray dried. In the former case, the solution from the mixing device D is in a Trough 3 conveyed, and a rotating roller 4 transfers part of the solution to a substrate 5- The solvent is removed from the applied solution by passing the substrate through a drying tunnel 6, whereupon it is rewound onto a take-up core 7.

When the composition is to be used in particulate form, the solution is dispensed from mixer D transferred to a spray drying device F, in which the solvent from the spray by a countercurrent removed by warm air. The particulate obtained Material 1 is mixed with a binder or carrier 2 in a mixing device E and then transferred into the coating tray 3. Thereafter, the same coating method as previously described is used .

Figure 2 relates to a two-part, thermographic image

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transmission element in which the printed image 12 is infrared radiation converts into heat. The heated areas cause the developer 10, which is applied to a substrate 11 was applied, sublimed and with the coating 9 with the soluble dye reacts, whereby color development occurs in the areas corresponding to the printed image. Layer 8 is simply a support or substrate for coating 9.

Figure 3 relates to a single layer thermographic image transfer element, in which the substrate 13 is coated with a mixture 14 of undeveloped dye, which in turn is provided with a coating that contains a developer 15. Infrared radiation does this printed image 16 is heated, whereby the developer in the coating 15 melts or decomposes and thereby with it the undeveloped dye in the coating 14 reacts.

FIG. 4 shows a pressure-sensitive transfer copier element. The substrate 17 is covered with an oleophobic coating 18 _S, for example gum arabic. A second coating 19 is applied to the coating 18. The coating 19 consists of a fragile layer _9, for example paraffin wax, which contains a colorless solution of a dye in the interstices _f . e.g. Ehodamine base as a soluble dye (rhodamine base solvent dye), dissolved in chlorinated naphthalene. A pressure exerted on the substrate 17 causes the fragile layer 19 to be transferred to the paper at the point indicated by 20 ". The same pressure also causes" the solution of the colorless dye to be pressed out onto the paper, where the soluble dye is either reacts with the acidic or polar components of the paper »creating an image»

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Figure 5 shows another pressure sensitive, two-ply Copy element is in which a substrate 26 with a layer 25 is coated, which contains colorless particles of the mixture of soluble dye / resin or binder and at which the solvent has been completely or substantially removed, for example by spray drying. The second Sheet consists of a substrate 21 on which a layer is applied, which microcapsules of the by a solvent contains developer held in liquid form. The solvent is or contains a solvent which is a real solvent for the spray-dried particles contained in the coating 25. Alternatively, the solvent encapsulated in layer 22 can be a polar solvent, that is itself a developer.

The image 24 is created by applying pressure in the area 23 the substrate 21 exerts. This causes the capsules of the solvent and the developer to break or rupture, releasing the developer and with the soluble dye / binder particles in the Layer 25 reacts.

Figure 6 shows a further pressure-sensitive, two-layer Copy element is, in which the substrate 32 with a layer 33 is coated, in which both the colorless particles of soluble dye / resin or binder, as described in Figure 1, as well as particles of a developer are dispersed. The image 30 is formed by looking at the substrate 27 Applying pressure. This has the effect that a solvent, for example xylene, from the layers contained in the upper layer 28, destroyed microcapsules 29 escapes. The solvent is transferred to the layer 31, creating the soluble dye and the developer can react with one another to form color.

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A further variation of the image-forming sheet described in FIG. 6 results from the reference to FIG 80 ⁰ C and 200 ⁰ C melts and that the binder which holds this coating on the substrate 34 should preferably be conductive. Alternatively, the substrate 34 could also be conductive.

When a pin 36 is brought into contact with the coating 33 and an electrical current is passed through the pin, an image is created in this area by electrothermal processes. In addition, a thermographic Image can be formed by bringing a black printed image 35 into contact with the substrate 34. Infrared radiation heats the image 35 », thereby increasing the temperature of the corresponding surface of the Layer 33 is heated. This causes the developer to melt and react with the particles of the soluble dye / binder.

From the foregoing, it can be seen that the image transfer sheet produced by the above method is widely applicable. As a pressure sensitive sheet, it can be used for general office use can be used, as a thermally activated sheet, it can be used as a calculator and computer printout sheet will. In the case of electric current development, it can be widely applied to facsimile equipments insert.

The compositions according to the invention can be summarized say that they develop soluble dyes

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hold »which have the following advantages over the chemically modified bases previously used;

1) they are much cheaper,

2) they have a larger one in the binder or resin binder system Stability on,

3) they give a color development with a substantial larger range of acidic and / or reducing agents; the choice of certain developers, such as tannic acid or phosphomolybdic acid leads to dyeings with very good lightfastness and

4) They are not subject to the reverse reactions of the chemically modified earbases, which - regardless of the storage conditions - lead to a quick fade =

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Claims (1)

PATENT CLAIMS 1. Color developing composition, characterized by a soluble dye in essentially colorless form, which is capable of color development in contact with and / or by reaction with an acidic and / or reducing compound, and a binder ₉ which is a wax or resin acts »that does not lead to the development of the soluble dye (dye base) and was mixed with the soluble dye in the presence of a non-developing solvent. 2. Composition according to claim 1, characterized in that it is in the soluble dye to the free base of a color base chosen from azo dyes, xanthenes, triarylmethanes ₅ Diphenylmethaii, triphenylmethane, azine and Phenazinfarb st open. 3. Composition according to one of claims 1 or 2, characterized in that it is the binder a resin is selected from acrylic resins, polystyrene, ethyl cellulose, ethyl hydroxyethyl cellulose, Polythene, chlorinated rubber, rubber hydrochloride, polyesters, polyvinyl chloride, polyvinyl acetate, vinyl toluene, Butadiene, acrylonitrile and their copolymers. 4. Composition according to one of the preceding claims characterized in that the binder and / or solvent are not polar and no free acid groups exhibit. 030036/0307 M / 20 035 5. Composition according to any one of the preceding claims, characterized in that the soluble dye 1 to 80% by weight of the total pesticides in the composition. 6. The composition according to claim 5, characterized in that the soluble dye 1 to 30 wt .-% of the makes up total solids of the composition. 7. Composition according to one of the preceding claims, characterized in that the solvent is selected from those with weak hydrogen bonds, including aromatic, aliphatic and chlorinated hydrocarbons. Composition according to any one of the preceding claims, characterized in that the non-developing Solvent is substantially removed after the composition is mixed. 9. Composition according to claim 8, characterized in that the non-developing solvent by Spray drying is removed. 10. Composition according to any one of the preceding claims »characterized in that it is in particulate form. 11. Composition according to any one of claims 1, 2 and 4 to 10, characterized in that the binder is a wax. 12. Composition according to claim 11, characterized in that that the binder is in the form of a wax 030036/0307 M / 20 035 The choice is made from paraffin waxes, microcrystalline waxes, polyethylene waxes and ceresin wax _{or similar} 13. Composition according to claim 12, characterized in that that the non-developing solvent is a non-volatile solvent that is selected is among paraffin oils, chlorinated paraffins, naphthalenes, biphenyls and phthalate esters. 14. Composition according to any one of the preceding claims, characterized in that more than just one soluble Dye is in colorless form. 15 «composition containing a color developing composition according to any one of the preceding claims and a carrier therefor, characterized by a resin dispersion or solution in which at least the binder for the color developing composition is essentially is insoluble. 16. Composition according to claim 15 »characterized in that that the binder is a resin and the carrier is a resin solution or dispersion based on water or alcohol. 17. Composition according to any one of claims 15 or 16, characterized in that the carrier also contains a developer contains. 18. Composition according to claim 17 »characterized in that that the developer is dissolved in the carrier, 19. Composition according to one of claims 15 to 18, characterized characterized in that there is also a filler in the carrier 030 0 36/0307 M / 20 035 is included after the application of the composition to a substrate following the essentially Removal of practically all solvents enables the surface to be written on. 20. Composition according to claims 17 or 18, characterized characterized in that the developer is a natural or synthetic tannin. 21. Composition according to one of claims 1 to 7, characterized in that the solvent in the Composition is included. 22. Coating on a substrate consisting of a composition according to one of the preceding claims. 23. A coating according to claim 22, characterized in that substantially all of the non-developing solvent and / or any other resin solvent present are removed. 24. Sheet or film material of any configuration containing a substantially dry coating comprising a composition according to any one of claims 1 to 25. sheet or film material according to claim 24 »characterized in that that it is essentially transparent. 26. Sheet or film material according to claim 24 »characterized in that the sheet or film is formed from paper and a layer is provided between the paper and the coating with the composition ₉ which prevents acid clay or other reactive materials from developing the color effect the color base of the composition. 030036/030 7 27. sheet or film material according to claim 26, characterized in that that the underlayer is made of gum arabic. 28. A method for transferring an image to a substrate »wherein on the substrate there is a substantially dry coating formed by applying a composition according to any one of claims 1 to 7, characterized in that the coating on the substrate is covered with a sheet * which contains a developer which is substantially in contact with the coating on the substrate ₉ and an image from the covering sheet onto the substrate or vice versa a) by applying pressure, b) by applying selective light or heat, or c) by using selective electrical discharges, in which the developer imagewise develops the soluble dye contained in the coating on the substrate, transmits. ο method according to claim 28, characterized in that 9 is used as the covering sheet, an acidic paper, the developer in the form of the acid groups present on the paper, and the image is transferred by pressure. 30. Sheet or film material having a substantially dry coating which can be obtained by the application of a composition according to any one of claims 1 to 7 and which has an encapsulated below, on or in the coating Contains developer. 030036/0307 M / 20 035 31. The method according to claim 28, characterized in that the coating on the second sheet contains a developer which can melt, sublime or decompose ^{at temperatures between 50 and 400 ° C.} 32. Sheet or filler material for the production of developable images with two matrices located thereon »where a matrix is in the form of a dry composition according to any one of claims 1 to 14 and the other matrix is a dried carrier dispersion or solution in which the binder is insoluble and which contains a developer » 33 sheet or film material according to claim 32, wherein the Binder is a resin. 34 sheet or film material according to one of claims 32 and 33, prepared by applying a composition according to any one of claims 15 to 20 to the Sheet or film substrate. 35 · sheet or film material according to one of claims 32 ■ to 34 »characterized in that the two matrices are in the form of coatings. 36. sheet or film material according to claim 35 »characterized in that that the first matrix was first applied to a substrate which is the plane of the sheet or Films limited. 37. sheet or film material according to any one of claims 32 to 36, characterized in that it is the carrier is a resin dispersion and / or solution. 38. sheet or film material according to claim 37, characterized in that 030036/0307 M / 20 035 indicates9 that "the carrier is a resin dispersion or solution on an aqueous or alcoholic basis. 39. sheet or film material according to claim 38, characterized in that that the developer is a natural or synthetic tannin. 40. sheet or film material according to any one of claims 32 to 39, characterized in that one of the matrices contains a microencapsulated solvent that when released under pressure, heat or leads to a relative selective mobility of soluble dye and developer in another way «, 41. Sheet or film material according to one of claims 32 to 40, characterized in that it is transparent. 42. Image-wise developable system, characterized by a) a soluble dye in a substantially colorless one Shape that is on a substrate and that is the base shape of a color base acts that in the reaction with a developer with acidic and / or reducing properties and a non-developing binder leads to color development, and b) a developer located on the substrate which, however, is not in the reactive presence of the in im Substantially colorless form present soluble dye is and that for imagewise development of the soluble dye can selectively migrate, 030036/03 0 7 M / 20 035 if a selective, image-sized pressure on the system » selective pictorial heat on the system or selective electrical discharges are applied to the system. 03 0 036/0307