CH662380A5 - COLORED COATINGS FOR THE PRODUCTION OF COATED PAPERS. - Google Patents

Description

The present invention relates to colored coating slips for the production of coated papers, characterized in that these coating slips contain a filler material which is colored with water-soluble polycationic dyes. The invention further relates to the use of such coating slips for the production of coated papers and filler materials which are colored with water-soluble polycationic dyes. The invention further relates to a process for the production of coated papers, characterized in that the above coating slip according to the invention is used for the production thereof.

Filling materials are primarily inorganic and organic white pigments, in particular finely divided silicates such as kaolin (china clay), talc, diatomite (kieselguhr or infusoria earth), Federweiss, soapstone, asbestos, calcium silicate, which is used when mixing a cold, concentrated calcium chloride solution with a cold one , concentrated sodium silicate solution is obtained in a particularly active form, quartz sand, asbestos, finely divided sulfates such as gypsum, annaline, lenzine, satin white (calcium sulfoaluminate), heavy spar,

Blanc fix, finely divided carbonates such as calcium carbonate (e.g. chalk), magnesite, patent white (whiterite), lead white, dolomite, zinc spar, finely divided oxides or hydroxides such as aluminum oxide or hydroxide, barite, TiCh, calcium hydroxide, burnt magnesia, zinc white , finely divided sulfides such as the Lithopone or zinc sulfide, finely divided calcium sulfite, condensation products of urea and formaldehyde such as the commercially available Pergopak (Ciba-Geigy) or Lytron (Monsanto). Preferred for dyeing with cationic dyes for dyeing paper are, in particular, kaolin, calcium carbonates, Blanc fix, titanium dioxide and talc, preferably kaolin, chalk and talc.

It is surprising that e.g. Chalk is also outstandingly suitable for the process according to the invention, in particular if the dyes mentioned below are used.

Of the polycationic dyes, metal-free or metallized dyes are particularly suitable which have an average of at least 1.3 quaternary or protonized nitrogen atoms as cationic groups per dye molecule.

The dyes can also have anionic groups, preferably sulfo groups, the molecule then having at least one excess cationic group. If there are x cationic groups, then x> 1.3 and the number y of anionic groups is then 0 <y <(x-1).

Biscationic metal complex dyes are preferred, preferably from the series of biscationic 1: 1 and 1: 2 metal complex azo dyes. For the 1: 2 complexes that

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have two dye units per metal atom, the above value x <1.3 refers to the individual dye unit (i.e. dye molecule in the dye complex) and not to the entire dye complex.

You can also use cationic phthalocyanine dyes, especially cationic copper phthalocyanine dyes or cationic anthraquinone dyes, as well as dyes with a fiber-reactive group.

The dyes preferably have a metal-free cationic or protonic molecular weight of at least 400, preferably 500-1500 and preferably 500-1000 and are substantive with respect to the filler, i.e. they draw at least 90% and preferably practically quantitatively onto the filling material from an aqueous solution at 20-90 ° C without auxiliary agents. Preferred are those dyes which after 90 minutes at boiling temperature in an electrolyte-free bath with a liquor ratio of 1:20 in 1/1 standard strength on mercerized cotton, have an absorption quotient (= ratio between extracted dye and dye in the bath) of 90-100% , according to the definition of DIN 54 000, resp. ISO standard RIOS / I, 1959, Part I.

Dyes which meet these conditions preferably have terminal or peripherally arranged cationic groups. A preferred group are e.g. Phthalocyanine dyes containing two or more cationic groups arranged peripherally on the planar phthalocyanine ring. Furthermore, dyes with a linear or stretched structure are preferred which have three or more aromatic or heterocyclic ring systems in the molecule, the 1.3 cationic groups on average being located exclusively on the terminal ring systems. Compounds are preferred two or more cationic groups, preferably with two cationic groups,

where a cationic group is located on a terminal ring system of the molecule.

Such dyes are known per se and have been described, for example, in the following patents and patent applications: in the German Offenlegungsschriften

1 061 010.1 064 661.1 621 702.2 250 676, 2 251 041,

2 604 699.2 627 680 and 2 810 246; in the U.S. patents

3 709 903.3 784 599.3 839 426.3 933 787.3 935 182.

3 996 282.4 046 502.4 103 092.4 146 558.4 153 598 and

4,213,897; in European patent applications 13 751, 14 677.14 678.15 232.15 233.15 511.16 726.24 321, 24 322, 34 725.38 299, 54 616, 56 574.62 824, 62 825.63 261 and

65 595.

Dyes, such as e.g. in German Offenlegungsschriften 19 03 058, 26 27 680, 29 15 323, 31 17 127.30 30 196.30 30 197.32 23 951 or in Europ. Patent applications Nos. 81 0171.9 and 81 81 0316.0 are described.

The following processes are suitable for the production of the colored pigments: The white pigment is slurried in water or dispersed by means of a nonionic and / or cationic dispersant, the dye content of the suspension or. the dispersion can be 0.1% to 90% and is advantageously 10-70%. The cationic dye in a solution of 0.1-70%, advantageously 5-40%, is mixed into this suspension with stirring. The temperature of the liquor can be 1-100 ° C and is advantageously kept at 20-70 ° C. The dyeing time is 10 seconds to 60 minutes, with dyeing generally 1-20 minutes, optionally in the presence of fixing agents known per se. The colored suspension can then be used. For use in paper coating slips, the suspension or dispersion is now preferably 0.1-10% by weight of dispersant such as e.g. Polyphosphate, polyacrylate, etc. supplied, the amount of dispersant from the

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The nature and concentration of the white pigment and the dye molecule and the amount of dye used is dependent. Suitable dispersants are also condensation products of sulfonated aromatic compounds with aldehydes such as formaldehyde. So e.g. Condensation products of sulfonated naphthalene, diphenyl, diphenyl oxide and related compounds with formaldehyde. Preferred are condensation products of β-naphthalenesulfonic acid with formaldehyde, which consist of units of the formula wCH2mffir

NaO ^ S SO-jNa are composed, also in combination with other dispersants such as polyacrylates. This is particularly the case when high amounts of dye are used or low coating paste viscosities have to be achieved. Such dispersant! are known.

The colored suspension resp. Dispersion can also be dewatered by filtration and / or centrifugation and / or spray drying and then dried. The further use follows after the usual procedure for the entry of white pigments resp. colored organic or inorganic pigments in the manufacture or coloring of coating pastes for papers.

Another method consists in homogeneously mixing the white pigments in dry form with powdered or granular dye and / or optical brightener and in this form being slurried with water or dispersed using a dispersant. The procedure is the same as for the use of dye solutions in white pigment slurries.

Depending on the color, the colored filling materials are used in a mixture with non-colored white pigments.

For the production of coating slips e.g. aqueous binder dispersions or emulsions based on acrylates, butadiene-acrylonitrile, butadiene styrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohols, polyvinyl acetate as well as co- and copolymers thereof, such as those used e.g. are described in DE-OS 29 38 896.

As already mentioned, dyed papers with excellent fastness to bleeding and good lightfastness are obtained according to the method of the invention. Due to the high affinity of these dyes for white pigments, there are practically no migration phenomena when drying, and this results - even with combination dyeings - level dyeings.

From a mechanical engineering point of view, the coated papers can be produced in a manner known per se.

If the dye does not completely absorb onto the substrate, the non-absorbed basic dye causes e.g. the formation of agglomerates and thickening, which negatively influence the theological properties of a coating paste, so that it is no longer spreadable. In particular, the stability of such coating pastes is usually significantly reduced. When using the cationic dyes defined above, these disadvantages do not occur, which is also manifested in the best dispersion stabilities and in the much better wet fastness of these dyeings.

The papers colored according to the invention can also be bleached without problems, in contrast to those produced with pigment dye. This is particularly important for the reprocessing of coated and colored scrap.

The dyed and knitted according to the invention

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Other papers are very easy to print on and are exceptionally well suited as copy papers. The following examples illustrate the invention.

example 1

285.7 parts of a 35% aqueous dispersion of English China Clay brand kaolin, containing 100 parts dry weight kaolin, become 10 parts by weight of a 25% solution of

[CUPc] - (CH2N® (C2H5) 3Cl®) 3 (Pc = phthalocyanine)

added with stirring at room temperature (20 ° C). After a dyeing time of 2 minutes, 1.5 parts by weight of a dispersant (polysalt F from BASF, a polyacrylate as Na salt) are added. Then 20 parts by weight of a synthetic

The result is an indifferent and deep blue colored paper with bleeding and light fastness as indicated in Example 1.

Example 3

100 parts by weight of chalk of the brand Omyalite 90 are slurried with 185 parts by weight of water and homogenized by stirring using the "Roth disperser" until the viscosity is stable (approx. 10 minutes). Then you set 10

see binder (Dow-Latex 620, based on butadiene-styrene) with 50% solids content introduced. Finally, the pH is adjusted to 8.5 with 25% ammonia. This results in a deep turquoise-colored coating paste with a solids content of approx. 40%.

This coating paste is now applied by means of a squeegee to a coating base paper of 80 g / m2 with a coat application of 20 g / m2 dry substance. It is then dried in a convection dryer at 105 ° C for 60 seconds. Io The result is an indifferent and deeply colored coated colored paper with excellent bleeding fastness in water and alcohol. Good lightfastness also results.

Example 2

15 The procedure is as in Example 1, but with 10 parts by weight of a 20% solution of

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Parts by weight of the dye according to Example 2 as a 20% solution. After a stirring time of 5 minutes, 0.5-1.5 parts by weight of dispersant (polysalt F) is added. After a further 2 minutes, the colored slurry is filtered off. 30 Even after repeated washing with well water, the filter cake remains deep blue in color and the filtrate is largely colorless. Further use can be as described in Example 1.

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Claims (9)

662 380 1. Colored coating slips for the production of coated papers, characterized in that these coating slips contain a filler material which is colored with water-soluble poly-cationic dyes. 2. coating slips according to patent claim 1, characterized in that they contain kaolin, chalk or talc as filler. 2nd PATENT CLAIMS 3. coating slips according to claim 1, wherein the filler is colored with metal-free or metallized polycationic dyes which have an average of at least 1.3 quaternary or protonized nitrogen atoms as cationic groups per dye molecule. 4. coating slips according to claim 3, characterized in that the filler is colored with biscationic metal complex dyes from the series of biscationic 1: 1 and 1: 2 metal complex azo dyes. 5. coating slips according to claim 3, characterized in that the filler is colored with cationic phthalocyanine dyes, preferably cationic copper phthalocyanine dyes, cationic anthraquinone dyes and / or dyes with a fiber-reactive group. 6. coating slips according to any one of claims 1-5, characterized in that the dyes have a metal-free cationic or protonic molecular weight of at least 400, preferably 500-1500 and preferably 500-1000 and are substantive with respect to the filler. 7. coating slips according to any one of claims 1-6, characterized in that the dyes have terminal or peripherally arranged cationic groups. 8. coating slips according to any one of claims 1-7, characterized in that they contain 0.1-10 wt .-% of a dispersant. 9. Process for the production of coated papers, characterized in that a coating slip according to one of claims 1-8 is used for its production. In the manufacture of filled papers, inorganic, mostly white pigments are used as fillers. Such papers are often colored, e.g. with direct dyes, acidic or basic dyes. Direct dyes are used to dye predominantly wood-free to slightly wood-containing papers, while basic dyes are suitable for dyeing papers with a high wood content. Care is taken to ensure that the dye bonds with the paper fiber as firmly as possible, e.g. to avoid bleeding later. Another method of coloring paper is to coat paper with a colored coating slip. White or colored pigments or a mixture of such pigments are introduced into the coating slip and the paper is coated with them. This process mainly uses pigment dyes. The use of white pigments together with water-soluble dyes in coating slips, especially for quality papers, has various disadvantages. Above all because the dyes do not soak up the substrate to be dyed and therefore cannot meet the authenticity requirements. When water-soluble dyes are used in general together with white pigments, as a result of the detrimental migration behavior of the dyes, especially when several dyes are used at the same time, uneven colorations and color depth fluctuations generally result. In addition, there are poor light fastness properties, especially with basic dyes. The addition of cationic dyes to anionically stabilized coating slips often leads to precipitation. By adding inorganic and / or organic colored pigments, the white pigment is not colored. The colored pigment often shows a different migration behavior than the white pigments during the drying process of coating pastes, which can lead to uneven dyeings. In addition, the cost-effectiveness of using color pigments is unsatisfactory compared to soluble dyes, especially in deep shades. It has now surprisingly been found that the disadvantages mentioned are eliminated if filler material dyed for dyeing paper with cationic dyes is used. In particular, using the selected cationic dyes specified below, level dyeings and high fastness properties are achieved, in particular high fastness to bleeding, e.g. in water, alcohol, milk or soap, an increased color yield as well as less pollution of the manufacturing plants and the waste water.