DE2636385A1 - Carbonless copying paper prodn. - by coating acceptor sheet with pore sealant, drying and coating with acid adsorbent - Google Patents

Abstract

In the prodn. of press.-sensitive colour reaction copying paper with a donor sheet having microcapsules and an acid adsorbent material on the acceptor sheet, coating is carried out in 2 stages. In the first stage, a subbing with development properties, which seals the pores of the paper, is applied, then the material is dried before applying the acid material. Thin acceptor coatings can be produced economically and continuously on small units. These coatings give copies of great colour intensity and stability. The pore sealant can be a novolak, zinc blende, tannin or conventional binder resins, dissolved in alcoholic and/or similar solvents. For the second stage, the compsn. contains a conventional acid adsorbent and also resin and solvent, but less than for the first coating.

Description

Method and device for the production of a pressure-sensitive Copy paper.

The invention relates to a method and a device for production of a pressure-sensitive copy paper that is used as a receiving sheet in a transfer system cooperates with a donor sheet, which in turn is provided with microcapsules which break under pressure and release color formers that form on the layer of the The receiving sheet react with color formation.

Such methods have been proposed many times. the Microcapsules of the donor sheet usually contain a solution of chromogenic materials, or leuco dyes, which after release by breaking the capsules with the adsorbing acidic layer on the receiving sheet with electron acceptance react to color, with the acceptor layer delivering electrons.

The usual chemical color reaction papers need for strong colors Copy a thick layer of at least 5g / m² dry on the receiving sheet. Since this means that at least 10 g / m2 must be applied in the wet state during production, are very extensive layer application and drying systems (mostly also calenders) necessary, especially with the usual aqueous coating compositions. Despite Thick layer is the carbon copy colors formed in many of these papers poorly stable and only slightly lightfast.

The invention has made it its task to produce inexpensive paper To provide ways with highly reactive thin recipient layers. In contrast to previous ones Process should be given the following advantages: The coating should be on small inexpensive systems, '' also be possible on modified web printing machines. The thin layer must dry so quickly and easily that after the coating Further processing stages such as printing, punching, etc. in the same work step

possible are. The thin coating must be in terms of color intensity and persistence of the copy compared to the conventional ones produced on expensive large-scale systems Copy papers with a thick layer must be equal to or even surpass them. Inexpensive wood-containing base papers should also be used for the receiving sheet can.

To solve this problem it is proposed that the coating takes place in two stages; such that in the first stage of the process, the pores of the The layer that closes the paper and already promotes color formation, and after intermediate drying in the second stage the acidic material is applied.

The two layers are expediently applied in series adapted printing works. Both flexographic and gravure printing can be used can be applied. One can also apply at least one layer on top of one known coating machine perform.

By closing the paper pores according to the invention in the first Process stage, the durability of the carbonless paper is increased, that is the paper retains its good write-through properties even with a thin coating for longer gliding periods at. This is caused by the fact that the electron donating layer of the second Process stage cannot penetrate the paper pores.

because the pa is already primed. As a result, the second layer sits on the surface.

Although it sticks to the primer with a strap, it stands voil with yours Amount available for the inclusion and color formation of the encoder component because they do not sink into the pores and fibers of the paper and are partially lost can. In addition, an economical use of the material is guaranteed, by lower order quantities and small, cheaper coating or printing systems produce the same effect.

The invention enables printing ink-like thin layers of to apply great color intensity and persistence of the copy on small attachments, which continuously carry out further processing steps such as printing in the same work step and punching.

Investigations and measurements of papers coated according to the invention have shown that in modified Druckmasclinen according to the system described applied thin layers equal to the usual thick painted layers or are superior in copy performance and durability. There are also already known systems in which the layer is applied like printing ink; However, these are compared to conventional papers in terms of the intensity of the copy inferior in a single cut.

As pore-closing materials can be used for the first stage of the process Novolac, zinc resin.

Tannin, common binder resins, dissolved in alc; '; ol icals and the like Solvents, are used: This layer already provides for certain Developer skills1 so that, in addition to the primer effect, there is also write-through properties result.

As acidic, adsorbing, electron donating materials for the second stage of the process, substances known per se, such as clay, and / or activated acid clay, zinc oxide, attapulgite, bentonite, microtalcum, zeolite, kaolin, silicon dioxide, Aluminum oxide, aluminum hydroxide, benzoic acid, benzene sulfonic acid, hydroquinone, Resorcinol, naphthol, lithopone, pyrocatechol, pyrogailol are used. Resins and solvents correspond to the first layer of primer, but are added to a reduced extent.

Metal salts are expediently used as a catalyst for the acidic material added. Zinc salts in particular have proven to be suitable.

Further details can be found in the following description of a Exemplary embodiment for an application device: The device consists from two adapted printing units 7, 7 * connected in series.

Each of these printing units consists of an ink tray 8, 8 *, in which the to be applied mass is included. The paint trough 8 contains the pore-closing material and the paint trough 8 * the acidic material. The material is fed over an inking roller4, 4 * transferred to the plate cylinder 5, 5 *.

Between the plate cylinder 5 and the impression cylinder 6 runs the paper web 1 to be coated. After the coating, it goes through a first drying section 9, which is only indicated schematically in the drawing. she can consist of a drying tunnel or cylinder, a hot air treatment, an irradiation with 1 infrared lamps, microwaves, UV rays or similar. exist.

The web 1 is optionally guided around a deflection roller 10 to then into the second printing unit 7 *, between the cliché cylinder 5 * and the Impression cylinder 6 * to run in. After coating with the acidic material from the ink trough 8 * the running paper web 1 is dried one last time at 9 *, the drying device is only indicated schematically. The double-coated Paper then undergoes further treatment (not shown) such as printing, stamping etc. fed or immediately rolled up.

L e r s e i t e

Claims (8)

Claims t 3 method for producing a pressure-sensitive Copy paper that is used as a receiving sheet in a transmission system with a donor sheet cooperates, which in turn is provided with microcapsules that the color former contained and break under pressure, the color former with one on the receiver sheet acidic adsorbing, electron donating material under color formation react, characterized in that the coating takes place in two stages, in such a way, that in the first stage of the process a primer that closes the pores of the paper with developing properties and after intermediate drying in the second stage that acidic material is applied. 2. Apparatus for performing the method according to claim 1, characterized gekerrnzeich that the application of the two layers in series adapted printing units (7, 7 *). 3 Apparatus according to claim 2, characterized in that the printing unit (7) in a manner known per se from ink trough (8), fountain roller (3), ink roller (4), There is a plate cylinder (5) and an impression cylinder (6) and two such printing units 17, 7 *) are connected in series in such a way that the slave sheet (1) after being looped around of the impression cylinder (6) via a drying section (9) and optionally a Deflection roller (10) runs, then the counter-pressure cylinder (6 *) of the second printing unit (7 *) wraps around and then passes a last drying section (9 *). 4. Apparatus for performing the method according to claim 1, characterized characterized in that the application of at least one layer directly or indirectly Gravure printing or on a coating machine takes place. 5. The method according to claim 1, characterized in that the pore-closing Materials for the first stage of the process novolac, zinc resins, tannins, usual Binder resins dissolved in alcoholic and / or similar solvents are used will. 6. The method according to claim 1, characterized in that the acid Adsorbing, electron donating materials for the second stage of the process in a manner known per se clays and / or activated acidic clay, zinc oxide, Attapulgite, bentonite, zeolite, microtalcum, kaol in, silicon dioxide, aluminum oxide, Aluminum hydroxide, benzoic acid, benzene sulfonic acid, hydroquinone, resorcinol, naphthol, Lithopone, catechol, pyrogallol are used, as well as resins and solvents according to claim 5, but to a reduced extent. 7. The method according to claim 6, characterized in that the acidic material Metal salts can be added as a catalyst. 8. The method according to claim 7, characterized in that ajs metal salts Zinc salts and the like be used.