EP0037477B1 - Copying system and method for its manufacture, and offset or printing dyes useful in this system - Google Patents

Description

• - ein Verfahren zur Herstellung von druckempfindlichen, kohlefreien Durchschreibesystemen, bei welchem auf einer Oberfläche des Papiersubstrates partiell oder vollflächig mit der Technik des Nass- oder Trockenoffsetdruckes oder des Buchdruckes eine Beschichtungskomposition aufgebracht wird, die Farbstoffvorläufer enthaltende Mikrokaspeln enthält;
• - die nach diesem Verfahren hergestellten Durchschreibesysteme;
• - eine Offsetdruck- bzw. Buchdruckfarbe, die aus Reaktionsharzen, Farbstoffvorläufer enthaltenden Mikrokapseln, Abstandhaltern, sowie weiteren Hilfs- und Zusatzstoffen besteht;
• - die Verwendung dieser Offsetdruck- bzw. Buchdruckfarben zur Herstellung druckempfindlicher, kohlefreier Durchschreibesysteme auf Offsetdruck- bzw. Buchdruckmaschinen.

The invention relates

• a process for the production of pressure-sensitive, carbon-free copying systems, in which a coating composition is applied to a surface of the paper substrate using the technique of wet or dry offset printing or letterpress, partially or over the entire surface, which contains microcapsules containing dye precursors;
• - the copying systems produced by this method;
• - An offset printing or letterpress ink, which consists of reactive resins, dye precursors containing microcapsules, spacers, and other auxiliaries and additives;
• - The use of these offset printing or letterpress inks for the production of pressure-sensitive, carbon-free copy systems on offset printing or letterpress machines.

Reaction carbon papers are known (see M. Gutcho, Capsule Technology and Microencapsulation, Noyes Data Corporation, 1972, pages 242-277; G. Baxter in Microencapsulation, Processes and Applications, edited by JE Vandegaer, Plenum Press, New York, London, pages 127-143).

Reaction carbon papers preferably consist of two or more sheets of paper laid loosely on top of one another, the upper one on the back containing a donor layer and the lower one on the front containing a receiver layer. In other words, a donor layer and a receiver layer are in contact with each other. The donor layer contains microcapsules, the core material of which is a solution of a color former in an organic solvent, and the receiver layer contains a material which develops the dye former into a dye. When writing, the capsules are destroyed under the high pressure of the writing instrument and the leaking core material hits the slave layer, so that a copy is created.

The receiver layer usually contains binders and pigments, e.g. active absorbents such as kaolin, attapulgite, montmorillonite, bentonite, acidic bleaching earth or phenolic resins. You can e.g. Use acid-activated dyes on the donor layer and acid-reacting components in the receiver layer.

A further development of these reaction carbonless papers are the “one-component” carbonless carbonless papers. In these, one side of a single sheet of paper carries the dye precursor, generally in the form of microcapsules, and at the same time the color developer. If pressure is now applied, e.g. using a typewriter or other writing tool, the capsule containing the color precursor is torn open and the color precursor reacts with the color developer surrounding it (see US Pat. No. 2,730,456).

The coating of the paper substrate for the production of carbon-free copying systems is generally carried out over the entire area with an aqueous coating composition, such as e.g. in German Offenlegungsschriften 1 934 457 and 1 955 542.

The disadvantage of the methods described is that after the coating composition has been applied, the water evaporates, which requires a considerable amount of energy. The need to dry further requires the use of complex and costly equipment to continuously dry a substrate that has been coated with an aqueous coating compound. Another but related problem relates to the removal of the contaminated water resulting from the manufacture and cleaning of the aqueous coating composition.

If volatile organic solvents are used in the production of the coatings, the excess solvent must also be evaporated in order to dry the coating. In this way, solvent vapors are created that pose particular risks.

Full-surface coatings are inefficient because in most cases only parts of the carbonless system are used.

Numerous methods have therefore become known for partially applying coating compositions to a paper substrate. According to the state of the art, aqueous or solvent-based coatings can be partially applied to a paper carrier by means of gravure printing or flexographic printing (see, for example, DE-OS 2 541 001, US Patents 3016308 and 3914 511). These processes also have the disadvantage of having to dry the coatings subsequently. For these reasons, it has been proposed, for example, in US Pat. Nos. 3,016,308, 3,079,351 and 3,684,549, as well as in German Offenlegungsschriften 2719914 and 2719935, to take up the microcapsules in waxes and to coat the paper carrier with such hot-melt systems.

Although these proposed measures prevent the removal of the solvents, the wax-like coating changes the character of the paper, since relatively large amounts of the waxes have to be applied.

In addition, the melting systems are applied to hot carbon printing machines which, although they allow printing, coating with wax materials and finishing to be combined in an online system, always require a separate system for each process step.

Processes for printing microcapsules in coating compositions on offset printing machines or even letterpress machines were not feasible in this prior art, since it was generally assumed that both in the production of the printing ink and in the distributor rollers of the printing machines and during the Printing process the shear and pressure forces would largely destroy the microcapsules. This invention is based on the finding that microcapsules incorporated in printing inks can be applied largely undamaged on a paper support on offset and letterpress machines.

The invention accordingly relates to a process for the production of pressure-sensitive, carbon-free copying systems, which is characterized in that a non-aqueous, essentially solvent-free coating composition based on a surface of the paper substrate using the technique of wet or dry offset printing or letterpress on part or all of the surface Reaction resin is applied, which contains dye precursors containing microcapsules.

The invention further relates to the copying systems produced by the process according to the invention.

This invention is also based on the finding that a coating composition composed of reactive resins, dye capsules containing microcapsules and spacers, and, if appropriate, further auxiliaries and additives can be applied to a paper web using offset printing machines or letterpress machines.

The invention accordingly also relates to an offset printing or letterpress ink which consists of reactive resins (preferably 90-20% by weight of the ink), microcapsules containing dye precursors (preferably 10-40% by weight of the ink), spacers (preferably 2- 20 wt .-% of the color), and other auxiliaries and additives (up to 50 wt .-% of the color).

The invention further relates to the use of these printing inks for the production of pressure-sensitive, carbon-free copy systems on offset printing or letterpress machines.

A large number of the microcapsules to be used for carrying out the process according to the invention and processes for their production are known. Thus, the long-known microcapsules can be used, which can be produced by coacervation or complex coacervation from gelatin and acacia, as well as gelatin and other inorganic and organic polyanions. Various such methods have become known, inter alia, in M. Gutcho, Capsule Technology and Microencapsulation, Noyes Data Corporation 1972.

In particular, microcapsules are used in the method according to the invention, the walls of which consist of polymers, polycondensation and polyaddition products.

The following overview is taken from G. Baxter, Microencapsulation, Processes and Applications, edited by JE Vandegaer, and shows a compilation of the capsule wall polymers that have become known according to the prior art.

Microcapsules with walls made of special polyacrylates, such as e.g. described in DE-OS 2 237 545 and DE-OS 2 119 933 can be used.

Furthermore, phenol or urea-formaldehyde condensates can be used as wall material, optionally also in combination with the capsule wall polymers mentioned above.

Microcapsules are preferably used in the process according to the invention, the shells of which consist of polyadducts of polyisocyanates and polyamines.

Isocyanates to be used for the production of such microcapsules are diisocyanates such as xylylene-1,4-diisocyanate, xylene-1,3-diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate-propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, Ethylidene diisocyanate, cyclo-hexyl-1,2-diisocyanate, cyclohexyl-1,4-diisocyanate, polyisocyanate prepolymers, e.g. Addition product of hexamethylene diisocyanate and hexanetriol, adduct of 2,4-tolylene diisocyanate with pyrocatechol, adduct of tolylene diisocyanate with hexanetriol, adduct of tolylene diisocyanate with trimethylolpropane, adduct of xylylene diisocyanate with trimethylolpropane, or the polyethyl compounds indicated above, or the polyethyl compounds corresponding to those described above or with trimethylolpropane.

Other modified aliphatic isocyanates are those based on hexamethylene-1,6-diisocyanate, m-xylylene diisocyanate, 4,4'-diisocyanatodicyclohexylmethane or isophorone diisocyanate, which have at least two functional isocyanate groups per molecule.

Other suitable compounds are polyisocyanates based on derivatives of hexamethylene-1,6-diisocyanate with a biuret structure, the preparation of which can be found in DE-AS 11 01 394 and 15 43 178 and in DE-OS 15 68 017 and 19 31 055.

The polyisocyanates that can be used can additionally be modified before use for microencapsulation by reaction with di- and trifunctional chain extenders, e.g. Water, with polyfunctional alcohols such as ethanediol, glycerol or trimethylolpropane or carboxylic acids such as succinic acid, adipic acid, sebacic acid in proportions of 0.01 to 0.5 mol per equivalent of isocyanate.

Instead of the isocyanate groups, carbodiimide, uretdione, uretonimine, uretidinedione diimine, 4-imino-oxazolinidinone (2), β-alkylene-propiolactone or cyclobutanedione (1,3) groups can also be used as reactive groups to be available.

For example, polyisocyanato-polyuretonimines, such as those formed by carbodiimidization of hexamethylene-1,6-diisocyanate containing biuret groups with phosphorus-organic catalysts, can be used by further reaction of primarily formed carbodiimide groups with isocyanate groups to form uretonimine groups. Furthermore, these isocyanates can be used in a mixture with one another and other aliphatic and aromatic isocyanates.

Depending on the reaction conditions, the resulting modified polyisocyanate can contain considerable proportions of oxadiazinetrione, triisocyanurate or sym. Triazinedioneimine as a structural element. Such products are also suitable as shell formers.

Diisocyanates of the formula are particularly suitable

• Ethylendiamin- (1,2), Bis- (3-aminopropyl)-amin, Hydrazin, Hydrazin-ethanol-(2), Bis-(2-methylaminoethyl) -methylamin, 1,4-Diaminocyclohexan, 3-Amino-1-methyl-aminopropan, N-Hydroxy-ethylethylendiamin, N-Methyl-bis-(3-aminopropyl)-amin, 1,4-Diamino-n-butan, 1,6-Diamino-n-hexan, Ethylen-(1,2)-diamin-N-Ethyl-sulfonsäure (als Alkalisalz), N-Aminoethylethylendiamin-(1,2) (Diethylentriamin), Bis-(N,N'-aminoethyl)-ethylendiamin-(1,2) (Triethylentetramin). Hydrazin und seine Salze werden im vorliegenden Zusammenhang ebenfalls als Diamine angesprochen.

Diamines suitable for reaction with the isocyanates mentioned are aliphatic primary or secondary diamines and polyamines, such as, for example:

• Ethylenediamine- (1,2), bis- (3-aminopropyl) -amine, hydrazine, hydrazine-ethanol- (2), bis- (2-methylaminoethyl) -methylamine, 1,4-diaminocyclohexane, 3-amino-1- methyl aminopropane, N-hydroxyethyl ethylenediamine, N-methyl-bis- (3-aminopropyl) amine, 1,4-diamino-n-butane, 1,6-diamino-n-hexane, ethylene- (1,2 ) -Diamine-N-ethyl-sulfonic acid (as alkali salt), N-aminoethylethylenediamine- (1,2) (diethylenetriamine), bis- (N, N'-aminoethyl) -ethylenediamine- (1,2) (triethylenetetramine). Hydrazine and its salts are also referred to as diamines in the present context.

Examples of the color formers are triphenylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds or the like.

• Beispiele für eine Triphenylmethanverbindung sind 3,3-Bis-(p-dimethylaminophenyl)-6-di- methylaminophthalid (nämlich Kristallviolettlacton, nachstehend als C.V.L. bezeichnet) und 3,3-Bis- (p-dimethylaminophenyl)- phthalid (nämlich Malachitgrünlacton).

Examples of the groups listed above are as follows:

• Examples of a triphenylmethane compound are 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (namely crystal violet lactone, hereinafter referred to as CVL) and 3,3-bis (p-dimethylaminophenyl) phthalide (namely malachite green lactone).

Examples of a diphenylmethane compound are 4,4'-bisdimethylaminobenzhydrylbenzylether, N-halophenylleucolamine, N-β-naphthylleucolamine, N-2,4,5-trichlorophenylleucolamine, N-2,4-dichlorophenylleucolamine or the like.

Examples of a xanthene compound are rhodamine-β-anilinolactam, rhodamine-β (p-nitro-aniline) lactam, rhodamine-β- (p-chloroaniline) lactam, 7-dimethylamine-2-methoxyfluorane, 7-diethylamine- 3-methoxyfluorane, 7-diethylamine-3-methylfluorane, 7-diethylamine-3-chlorofluorane, 7-diethylamine-3-chloro-2-methylfluorane, 7-diethylamine-2,4-dimethylfluorane, 7-diethylamine-2,3- dimethylfluorane, 7-diethylamine- (3-acetylmethylamine) -fluorane, 7-diethylamine-3-methylfluoroane, 3,7-diethylaminefluoroane, 7-diethylamine-3- (dibenzylamine) -fluoroane, 7-diethylamine-3 ( methylbenzylamine) -fluorane, 7-diethylamine-3- (chloroethylmethylamino) -fluorane, 7-diethylamine-3- (dichloroethyl-amine) -fluorane, 7-diethylamine-3 (diethylamine) -fluorane or the like.

Examples of a thiazine compound are N-benzoylleucomethylene blue, o-chlorobenzylleucomethylene blue, p-nitrolbenzoylleucomethylene blue or the like.

Examples of a spiro compound are 3-methyl-2,2'-spirobis (benzo (f) chromium) or the like.

Solvents that dissolve these color formers are e.g. chlorinated diphenyl, chlorinated paraffin, cottonseed oil, peanut oil, silicone oil, phthalate ester, phosphate ester, sulfonate ester, monochlorobenzene, furthermore partially hydrogenated terphenyls, alkylated diphenyls, alkylated naphthalenes, aryl ethers, aryl alkyl ethers, higher alkylated benzene and others which can be used alone or in combination.

Diluents are often added to the solvents, e.g. Kerosene, n-paraffins, isoparaffins.

To produce the microcapsules by the polyaddition process, the colorants and the isocyanate are first dissolved in the solvents mentioned and this organic phase is emulsified in the continuous aqueous phase, which may contain protective colloid and, if appropriate, emulsifiers. An aqueous polyamine solution is added to the emulsion in a stoichiometric amount to the polyisocyanate in the organic phase.

Protective colloids and emulsifying aids are added to the aqueous phase to emulsify and stabilize the emulsion formed. Examples of such products acting as protective colloids are carboxymethyl cellulose, gelatin and polyvinyl alcohol.

Examples of emulsifiers are ethoxylated 3-benzylhydroxybiphenyl, reaction products of nonylphenol with different amounts of ethylene oxide and sorbitan fatty acid ester.

The microcapsules can be produced continuously or batchwise. Dispersing devices which generate a shear gradient are generally used. Examples include blade, basket, high-speed stirrers, colloid mills, homogenizers, ultrasonic dispersers, nozzles, steel nozzles, and Supraton machines. The strength of the turbulence during mixing is primarily decisive for the diameter of the microcapsules obtained. Capsules from 1 to 2000 µm in size can be produced. Capsules with diameters of 2 to 20 j.1m are preferred. The capsules do not agglomerate and have a narrow particle size distribution. The weight ratio of core material to shell material is 50-90 to 50-10.

The microcapsules are taken up in suitable resinous binders for application to the paper support by the process according to the invention and formulated into a printing ink suitable for wet or dry offset printing or for letterpress printing.

For example, the procedure can be such that the aqueous microcapsule dispersions are stirred into the binder and the water is then drawn off in vacuo. Such processes have also become known for incorporating pigments into printing inks as the so-called flush process.

Another method consists, for example, in that the aqueous capsule dispersions are spray-dried and converted into agglomerate-free capsule powder and then incorporated into the printing inks by known methods.

Spray drying microcapsules is already known in the art. Other known drying techniques can also be used to manufacture the capsule powder.

The microcapsule powders are invented according to the Process according to the invention incorporated into binders which are used according to the known prior art for producing a printing ink which can be processed in wet or dry offset printing or letterpress printing.

Offset printing inks and letterpress inks are known.They contain a reaction resin, i.e. an organic resin, which can be hardened by a chemical reaction (e.g. with atmospheric oxygen or peroxide, or UV radiation or electron radiation).

Combinations of different viscous stand oils with air-drying alkyd resins, hard resins or resin varnishes are primarily used as binders for book and offset printing inks. The latter are made by dissolving natural or synthetic resins in mineral oil.

Other suitable starting materials for the production of binders include in the "Lackrohstoffabellen" by E. Karsten 6th edition 1976, Curt R. Vincentz Verlag Hannover and in "Printing and Litho Inks" by Herbert Jay Wolfe, 6th edition 1967 McNair Donald Company, New York City.

• 1. Ausreichende Verträglichkeit mit den üblichen Standölen und Mineralölen möglichst schon bei Raumtemperatur, sowie weitgehende Kombinierbarkeit mit anderen Bindemitteln, Hartharzen oder Harz-ÖI-Verkochungen.
• 2. Gutes Benetzungsvermögen für die Mikrokapseln, um den Anreibeprozess zu vereinfachen.
• 3. Hohe Aufnahmefähigkeit für die Mikrokapseln zur Erzielung farbstarker Durchschriften.
• 4. Kurze Trocknungszeiten.
• 5. Hohe Glanzgebung.
• 6. Voll ausreichende Haft- und Scheuerfestigkeit auf Papier, Kunststoff- und Metallfolien.
• 7. Gutes rheologisches Verhalten, das zusammen mit dem der Mikrokapseln den einwandfreien Transport der Druckfarbe innerhalb der Maschine gewährleistet und auch auf schnellaufenden Druckmaschinen kein Spritzen oder Rupfen der Druckfarbe verursacht.

The requirements placed on the printing ink binder for the process according to the invention are as follows:

• 1. Sufficient compatibility with the usual base oils and mineral oils, if possible at room temperature, as well as extensive combinability with other binders, hard resins or resin-oil boilings.
• 2. Good wetting ability for the microcapsules to simplify the rubbing process.
• 3. High absorption capacity for the microcapsules to achieve strong color copies.
• 4. Short drying times.
• 5. High gloss.
• 6. Fully adequate adhesion and abrasion resistance on paper, plastic and metal foils.
• 7. Good rheological behavior which, together with that of the microcapsules, ensures that the printing ink is transported properly within the machine and that it does not cause the printing ink to splash or crack, even on high-speed printing machines.

This short list already shows that a binder alone can hardly combine all of the desired properties and that one generally works with binder combinations.

For example, vinyl group-containing monomers or also acrylates and methacrylates can be added to the binders that may be used, in particular also radiation-curing resins.

Book and offset printing inks also contain - in small quantities - various auxiliaries, e.g. Desiccants and skin contraceptives, as well as printing oils and printing pastes (cf. W. Wacenski in "Der Polygraph" Issue 12, 1980, pp. 1016-1021).

Desiccants (= drying accelerators) are oil and gasoline-soluble metal compounds predominantly of cobalt, lead and manganese with organic acids such as fatty, resin or naphthenic acid.

Depending on the content of drying components in the printing ink (oils, alkyd resins, desmalkyd types), small amounts of siccative (by 2%) can be used in order to shorten the drying time of the printing ink. Too large quantities can cause the ink to dry too hard (there are numerous difficulties, especially when printing several colors together) or even delay drying.

Skin contraceptives are intended to prevent the drying of the book and offset printing inks in the can or the drying on the rollers of the printing machine - possibly with a temporary machine standstill. Skin contraceptives are volatile (oximic) or non-volatile (phenolic) in nature. Their effect is opposite to that of siccatives. They are also added to the printing ink in only small amounts (1-5%). Printing aids such as printing oils or printing pastes allow the capsule-containing coating composition to be further adapted to the prevailing processing conditions.

Pressure oil, a mixture of spindle oil (mineral oil) and linseed oil, reduces the consistency of the composition and improves its striking away. Printing pastes make the color "shorter"; these pastes are usually obtained by melting waxes, petroleum jelly or wool fat in mineral oils. They have no drying properties and are strictly different from dry pastes (siccatives).

To prevent agglomeration of the microcapsules, dispersing aids, preferably from the group of the cationic surfactants, can be added to the printing ink.

In order to prevent destruction of the microcapsules when rubbing the printing ink and during the printing process itself, in a preferred embodiment, so-called spacers are added to the printing ink in amounts of 10-30% by weight, based on the amount of microcapsules. According to the known prior art, these spacers are also used in the production of the conventional carbonless carbonless papers. For example, they can consist of cellulose fiber particles or starch granules, the diameter of which is usually 1.5-2 times the microcapsule diameter.

Pigments and auxiliaries which have a favorable effect on the opacity of the coating can be added as further additives.

The amount of microcapsules that is incorporated into the binding formulation depends on the requirements that must be placed on the finished printing ink. The amount of capsules is set according to the method according to the invention as high as is reasonable taking into account the rheology and "speed" of the finished printing ink, on the other hand to apply an optimal amount of microcapsules with the lowest possible coating weight.

To formulate the printing ink, for example, the binder formulation can be presented and the dry capsules and other additives can be introduced using a planetary mixer.

The binding formulation thus produced is then rubbed in several passages on the three-roll mill.

As already stated, it is also a method which has long been known for the production of printing inks, to stir aqueous capsule dispersions into the binder formulation and then to evaporate the water in vacuo (flush process).

The binder formulation thus produced can be printed on commercially available offset printing machines using the wet or dry offset process.

Wet offset printing - or more often just referred to as offset printing - is the classic flat printing process, in which printing and non-printing areas are on almost one level. Printing is made possible by the mutual repulsion of fat and water. The printing areas are prepared so that they repel water and thereby take on the oleophilic printing ink, while the non-printing areas are hydrophilic and repel printing ink.

Offset machines therefore have ink and dampening roller systems that wet the printing plate on a plate cylinder and place the print image on the paper web via a rubber cylinder.

“Dry offset” uses the same printing press, but works without a dampening system. This printing process is therefore often referred to as "indirect letterpress".

The way of working distinguishes between sheetfed and web offset. While trimmed sheets are printed in sheetfed offset, web offset is printed on a paper web that is unwound from rolls.

Offset printing is therefore part of the long-known state of the art, and suitable printing presses with which the method according to the invention can be carried out are therefore commercially available.

Printing is preferably carried out in succession in a web offset printing press with a plurality of printing units. Such printing machines are already commercially available for multi-color offset printing.

It is a particular advantage of the method according to the invention that such multicolor offset printing machines can be used to print in one operation and the carbonless paper according to the invention can be produced.

The binding formulation can also be printed on commercially available letterpress machines.

Letterpress is therefore part of the long-known state of the art, and suitable printing presses with which the method according to the invention can be carried out are therefore commercially available.

It is possible to integrate additional devices into the printing machines for better and faster drying of the papers produced in this way, for example warm air blowers, which dry the coatings quickly or, if radiation-curable binders are used, to attach an appropriate radiation source.

A particular advantage of the method according to the invention is that no special requirements are imposed on the paper carrier. For example, commercially available CF papers can be used as paper supports, the front of which are already coated with a color developer and which can be printed on the back with the printing inks according to the invention.

However, normal, uncoated papers can also be used and the developer composition can also be applied in the printing press.

In a particular embodiment of the present invention, the color-developing substances can be incorporated directly into the microcapsule-containing printing inks.

So-called one-component reaction papers can be produced by printing printing inks, which also contain microcapsules containing dye precursors and color developers, on the top of the paper carrier web.

Color developing substances are known. They are usually acidic clays, such as montmorillonites, bentonites and smectites or phenolic compounds.

Further explanations can be found in the examples below.

example 1

• In 440 g Drucklack (Brillantglanzüberdrucklack 10 754 der Druckfarbenfabrik Gebr. Schmidt GmbH, Frankfurt) wurden 200 g Mikrokapselpulver eingerührt. Das Mikrokapselpulver war weitgehend agglomeratfrei und bestand aus Kapseln der mittleren Korngrösse von 5 pm. Die Kapseln waren ferner dadurch gekennzeichnet, dass die Wände aus einem Polyadditionsprodukt aus dem Oxadiazintrion von Hexamethylendiisocyanat und Diethylentriamin bestanden. Der Inhalt der Kapseln war eine 2,7%ige Lösung von Kristallviolettlacton in Diisopropylnaphtalin. Das Kern/ Wand-Verhältnis der Kapseln betrug 85:15.

An offset printing ink was produced as follows:

• 200 g of microcapsule powder were stirred into 440 g of printing varnish (brilliant gloss overprint varnish 10 754 from the printing ink factory Gebr. Schmidt GmbH, Frankfurt). The microcapsule powder was largely free of agglomerates and consisted of capsules with an average grain size of 5 pm. The capsules were further characterized in that the walls consisted of a polyaddition product from the oxadiazinetrione of hexamethylene diisocyanate and diethylene triamine. The content of the capsules was a 2.7% solution of crystal violet lactone in diisopropyl naphthalene. The core / wall ratio of the capsules was 85:15.

After the microcapsules had been stirred into the printing varnish, 55 g of small cellulose fibers with an average size fraction of 50 μm were added. 85 g of printing oil (printing oil special from the printing ink factory Gebr. Schmidt GmbH, Frankfurt) were also added.

The mixture was rubbed 5 times on a three-roll mill. The coating composition formulated in this way was used as dry offset printing with an offset printing machine (Heidelberg offset printing press factory, format 64 x 46) on paper with a basis weight of 40g / m ² .

The application weight of the coating was 4.2 g / m ² . The paper was then placed with the printed side on a commercially available CF paper, which was coated with color-developing substances. When using a normal writing printer, legible copies could be obtained on the CF sheet.

In a test, a further 7 base papers were placed on a combination of the printed CB paper and CF paper, and a square of the area 4 x 4 cm was inscribed as narrowly as possible with the letter small «w» using a typewriter with a constant keystroke .

The 8th copy appearing on the CF paper was examined with a reflectance measuring device (Elrephomat from Zeiss) for the loss of reflection compared to unlabelled paper and the corresponding value was determined.

wobei

• I = gemessener Remissionswert
• 1₀ = Remisssionswert des unbeschrifteten Papiers.

The remission value is defined by

in which

• I = measured reflectance value
• 1 ₀ = Remission value of the unlabelled paper.

A remission value of 17.9% was measured.

Example 2

The procedure was as described in Example 1, with the difference that a coating weight of 9 g / m ^{2 was} applied to the paper.

In the remission measurement of the 8th copy according to the method described in Example 1, a remission value of 33% was measured.

Example 3

A 30% aqueous microcapsule dispersion was produced, the microcapsule walls of which consisted of a polyaddition product of the oxadiazinetrione of hexamethylene diisocyanate and a polyamine. The capsule contents were a solution of 2.7% crystal violet lactone and 0.9% benzoyl leukomethylene blue in di-isopropyl diphenyl. The core / wall ratio of the microcapsules was 83:17.

The 30% capsule dispersion was converted into a largely agglomerate-free capsule powder by spray drying. The mean capsule diameter was found to be 7.3 pm.

300 parts by weight of urethane-modified alkyd resin (Desmalkyd L 181 from Bayer AG) were placed in a planetary mixer and 125 parts by weight of the microcapsule powder prepared were stirred in. 75 parts by weight of linseed oil-stand oil were added.

The mixture thus mixed was rubbed three times on a three-roll mill and the paint thus pasted was deaerated in a vacuum chamber. The printing ink produced in this way, containing 25% by weight of microcapsules, was squared with a web offset machine with a Dahlgren dampening system (manufacturer: Muller Martini) using a wet offset process onto the back of a commercially available CF paper (Giroset - from Feldmühle) a square with a side length of 5 cm printed on.

The application weight of the coating was 5.5 g / m ² and after drying a spot-coated carbonless carbonless paper was obtained.

When labeling several superimposed papers produced in this way, a clearly legible copy could be created within the printed squares.

The following example describes the production of the printing ink according to the invention by the flush process known in the printing ink industry.

Example 4

300 parts by weight of urethane-modified alkyd resin (Desmalkyd L 181 from Bayer AG) and 75 parts by weight of linseed oil-base oil were placed in a vacuum kneader. 125 parts by weight of a 30% strength microcapsule dispersion, prepared in accordance with Example 3, were slowly added with constant stirring. The vacuum kneader was evacuated with continued stirring and heated to a temperature of about 60 ° C until all the water had evaporated.

A printing ink containing 25% of microcapsules was obtained, which was printed with a sheet-fed offset printing machine (Heidelberger Offsetdruckmaschinenfabrik) on the front of a commercially available CF paper (Giroset CF from Feldmühle) in the form of a square with a side length of 5 cm. The coating weight was 5 g / m ² and a spot-coated one-component reaction paper was produced by the process described, which gave good copy results when superimposed within the square-shaped imprint.

Example 5

A 30% aqueous microcapsule dispersion was produced, the microcapsule walls of which consisted of a polyaddition product of the oxadiazinetrione of hexamethylene diisocyanate and a polyamine. The capsule contents were a solution of 2.7% crystal violet lactone and 0.9% benzoyl leukomethylene blue in di-isopropyl diphenyl. The core / wall ratio of the microcapsules was 83:17.

The 30% capsule dispersion was converted into a largely agglomerate-free capsule powder by spray drying, the mean capsule diameter of which was determined to be 7.3 gm.

30 parts by weight of urethane-modified alkyd resin (Desmalkyd ( ^R ) L 181 from Bayer AG) were placed in a planetary mixer and 125 parts by weight of the microcapsule powder prepared were stirred in. 75 parts by weight of linseed oil stand oil were added.

The mixture thus mixed was rubbed three times on a three-roll mill and the paint thus pasted was deaerated in a vacuum chamber. The printing ink containing 25% by weight of microcapsules produced in this way was printed with a letterpress machine (manufacturer: Heidelberger Maschinenfabrik) using the letterpress method on the back of a commercially available CF paper (Giroset-CF from Feldmühle) with the capital letter W in a size of 10 cm.

The application weight of the coating was 5.5 g / m ² and after drying a spot-coated, carbon-free carbonless paper was obtained.

When writing on several superimposed papers produced in this way, a clearly legible copy could be generated within the printed letter.

Example 6

• In 275 g Drucklack (Brillantglanzüberdrucklack 10 754 der Druckfarbenfabrik Gebr. Schmidt GmbH, Frankfurt/M.) wurden 200 g Mikrokapselpulver eingerührt. Das Mikrokapselpulver war weitgehend agglomeratfrei und bestand aus Kapseln der mittleren Korngrösse von 5 pm. Die Kapseln waren ferner dadurch gekennzeichnet, dass die Wände aus einem Polyadditionsprodukt aus dem Oxadiazintrion von Hexamethylendiisocyanat und Diethylentriamin bestanden. Der Inhalt der Kapseln war eine 2,7%ige Lösung von Kristallviolettlacton in Diisopropylnaphtalin. Das Kern/Wand-Verhältnis der Kapseln betrug 85:15.

A letterpress ink was made as follows:

• 200 g of microcapsule powder were stirred into 275 g of printing varnish (brilliant gloss overprint varnish 10 754 from the printing ink factory Gebr. Schmidt GmbH, Frankfurt / M.). The microcapsule powder was largely free of agglomerates and consisted of capsules with an average grain size of 5 pm. The capsules were further characterized in that the walls consisted of a polyaddition product from the oxadiazinetrione of hexamethylene diisocyanate and diethylene triamine. The content of the capsules was a 2.7% solution of crystal violet lactone in diisopropyl naphthalene. The core / wall ratio of the capsules was 85:15.

The mixture was rubbed 5 times on a three-roll mill. The coating composition thus formulated was applied as letterpress using a letterpress machine (Heidelberger Maschinenfabrik) to paper with a basis weight of 40 g / m ² .

The application weight of the coating was 5.5 g / m ² . The paper was then placed with the printed side on a commercially available CF paper, which was coated with color-developing substances. When using a normal writing print, easily legible copies could be achieved.

Claims (4)

1. Process for the production of pressure-sensitive, carbonless transfer systems, characterised in that a non-aqueous, substantially solvent-free coating based on reaction resin and containing microcapsules containing dye precursors is applied to part or all of at least one surface of a paper substrate by the technique of wet or dry offset printing or letterpress printing.

2. Pressure-sensitive, carbonless copying systems, produced according to Claim 1.

3. Offset or letterpress printing ink, consisting of

1.) reaction resins,

2.) microcapsules containing dye precursors,

3.) spacers having a particle size 1.5 to 5 times the diameter of the microcapsule,

4.) auxiliaries and additives.

4. Use of the offset and letterpress printing inks according to Claim 3 for the production of pressure-sensitive, carbonless copying systems on offset and letterpress printing machines.