NL8301156A - A COLORED COATING PRODUCT, FILLERS, METHOD FOR MANUFACTURING A COLORED, COATED PAPER PRODUCT AND A COLORED PAPER PRODUCT SO GIVEN. - Google Patents

Description

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A colored coating product, fillers, method of manufacturing a colored coated paper product and a colored paper product thus obtained.

It is common practice in the manufacture of paper to use fillers, generally white inorganic pigments. Such paper products are often painted or colored, for example with direct, acidic or basic dyes. Direct dyes are mainly used for dyeing paper that does not contain wood or a low wood content, while basic dyes are suitable for dyeing paper with a high wood content. It is desirable for the dye to bind it as strongly as possible to the paper fibers, so as to avoid subsequent bleeding or diffusion of the color.

Fillers can be added to the pulp from which the paper is made, but high-quality paper products are often coated with a product containing an aqueous filler paste together with a binder, for example starch or a synthetic resin, and optionally a dispersant. For coated paper, another method of dyeing or coloring paper relies on applying to it a colored coating product, which generally contains one or a number of colored pigments, as the sole filler or together with a white pigment. However, if a mixture of white and colored pigments is used, these pigments often migrate to different degrees during drying, which can lead to non-uniform dyeings. In addition, the use of pigments is less efficient than that of soluble dyes, especially for deep shades.

It is known to add water-soluble dyes to coatings containing a white pigment. However, this has a number of drawbacks, especially 8301156> * 2 for high quality paper. This is in particular due to an insufficient absorption of the dye by the substrate, which leads to unsatisfactory fastness properties. For all water-soluble dyes used together with white pigments, it can generally be noted that the differences in migration properties, especially when using a mixture of dyes, lead to non-uniform dyeings and variations in color depth . In addition, especially with basic dyes, the light fastness is poor and the addition of cationic dyes to an anionically stabilized coating system often causes a precipitate to form.

It has now been found that these drawbacks can be overcome by dyeing the filler before incorporation into the coating product with a water-soluble polycationic dye. Especially good results can be obtained by using selected groups of cationic dyes, as described below.

Thus, the invention provides a colored paper coating product containing an aqueous paste or filler dispersion dyed or dyed with a water-soluble polycationic dye along with a binder.

Suitable fillers can be of an organic nature, such as, for example, urea-formaldehyde condensation products, such as the commercially available products Pergopak® (Ciba-Geigy) or Lytron® (Monsanto), but are preferably inorganic in nature. It is recommended that the filler be a white inorganic pigment. Examples are finely divided silicates, for example, kaolin (porcelain earth), talc (soapstone), diatomite (kieselguhr or filter earth), Vienna lime, asbestine, calcium silicate (available in a particularly suitable form by a cold, concentrated solution of to mix calcium chloride with a cold, 8301156 7 to 3 concentrated sodium silicate solution) ^ quartz sand and asbestos * sulphates, for example gypsum, annaline, lenzine, a calcium sulphate product (calcium sulphoaltuninate), barite and zinc white (both barium sulphate), carbonates, e.g. 5 calcium carbonate (e.g. lime ), magnesite, whiterite, lead white, dolomite and calamine, oxides or hydroxides, for example aluminum oxide, barites, titanium dioxide, slaked lime, calcined magnesium oxide and zinc white, sulphides, for example lithopone and zinc sulphide, and sulphites, for example calcium sulphite. Recommended fillers for dyeing with cationic dyes are kaolin, calcium carbonate, talc, zinc white and titanium dioxide, in particular kaolin, calcium carbonate and talc. It is surprising that even inexpensive fillers, such as lime, give excellent results, especially with the selected groups of cationic dyes.

Polycationic dyes are intended to mean dyes with at least 1.3 cationic groups (quaternary or protonated nitrogen atoms) per dye molecule, an incomplete number of cationic groups being to be taken as an average value for the molecules of the dye concerned. The dyes may also contain anionic groups, in particular sulfonic acid groups, but if such groups are present, the number of cationic groups per molecule must be at least greater than the number of anionic groups per molecule. Expressed in numerical values, if there are x cationic and y anionic groups per molecule, then x 5 1.3 and 0 ^ y ^ (x-I). The dyes are in particular bis-cationic.

The dyes can be either metalized or contain no metal, but metal complex dyes are recommended, especially 1: 1 and 1: 2 metal complex azo dyes. For the 1: 2 complexes, containing two dye units per metal atom, the 830 1 1 5 6 4 requirement of at least 1.3 cationic groups per mole molecule applies to each dye unit and not to each molecule of the complex. Like azo dyes, other cationic dyes, for example phthalocyanine (preferably copper-5 phthalocyanine) dyes and anthraquinone dyes, can be used. Dyes containing a fiber-reactive group can also be used.

Preferably, the dyes, as cation containing no metal, have a molecular weight of at least 400, in particular 500-1000. Preferably they are substantive to the filler to be used, i.e. they are made from an aqueous solution containing 1% dye, based on the weight of the filler, through the filler at a temperature between 20 and 90 ° C and without application of paint aids included to a degree of at least 90%.

Especially recommended dyes are those that are highly absorbed by cotton, as measured by the following test: the dye will have a take-up ratio (the ratio of the dye absorbed by the substrate to the total amount of dye in the bath) of 90-100%, as defined by DIN 54000 or ISO RIOS / I 1959, part 1, when on mercerized cotton at a standard depth of 1/1 from a boiling, aqueous, non-electrolyte, bath at a ratio of 20: 1 from liquid to material and a paint time of 90 minutes was painted.

Dyes that meet these conditions are mainly those with peripheral or terminal cationic groups in the molecule. A recommended group of dyes are the phthalocyanine dyes containing two or more cationic groups attached to the periphery of the planar phthalocyanidation system. Another recommended group of dyes have a substantially linear structure comprising three or more homo or heteroaromatic rings or condensed ring systems, directly or by bridging. 830 1 1 5 6

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5 forming groups are joined * such that there are two terminal rings or ring systems and one or more intermediate rings or ring systems, with on average at least 1.3 cationic groups per molecule attached to terminal rings or ring systems and none others present elsewhere * In a particularly recommended group, there are two or more, especially two cationic groups per molecule, one or more, preferably one, on each terminal ring or ring system and no others elsewhere.

Dyes with the aforementioned properties and structure characteristics are known and are described, for example, in the following published patents and patent applications: German Patent Applications Laid-open: 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; U.S. Patent Nos. 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; and published 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. Particularly recommended cationic dyes are those described in published British patent applications 2,076,421A, 2,081,734A, 2,082,615A and 2,104,538A, British patent 2,019,873 and published European patent application 41,040.

The colored or dyed filler can be obtained by incorporating the white pigment into a paste with water or by dispersing it in water using a nonionic and / or cationic dispersant, the solids content of the resulting paste or dispersion is between 0.1 and 90% by weight, preferably between 10 and 70% by weight. Then, a 0.1-70 wt.% Aqueous solution, preferably a 5-40 wt.% Solution, of the cationic dye, is added to the stirred paste or dispersion at a temperature between 1 and 100 ° C, preferably between 830 1 1 5 6 ψ 6 20 and 70 ° C, added. The required paint time is between 10 seconds and 60 minutes, with a time between 1 and 20 minutes generally being sufficient. A conventional fixative can be used if desired.

Alternatively, the dry white pigment can also be intimately mixed with a dry dye in powder or granular form and the resulting mixture can be pasted with water into a paste or dispersed in water using a dispersant. The paint conditions are then the same as stated above.

The resulting colored or dyed pigment can be separated, for example, by filtration, centrifugation or spray drying, and the product can be further washed and dried if desired. It is also possible to use the colored slurry directly in the next step.

When preparing the coating product, it is desirable to add 0.1-10% of a dispersant, for example, a polyphosphate or polyacrylate. Other suitable dispersants include condensation products of sulfonated aromatics with aldehydes, for example condensation products of sulfonated naphthalene, diphenyl, diphenyloxide and related products with formaldehyde. The recommended dispersants are (Λ 25 condensation products of ρ-naphthalenesulfonic acid with formaldehyde, which contain units of the structure listed in formula 1 on the formula sheet.

These dispersants, which are known, can also be used in conjunction with other dispersants, such as polyacrylates, especially if large amounts of dye are used or low coating viscosities are to be obtained.

The coating product may contain any conventional aqueous binder dispersion or emulsion, for example, die or base of starch, acrylates, butadiene-acrylonitrile, 83 0 1 1 5 6 Φ τ'-7-butadiene-styrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate and copolymers and mixtures thereof, as described, for example, in German Patent Application Laid-Open No. 2,938,896.

If light shades of color are desired, the filler colored in suitable amounts / can be mixed with uncoloured white pigment.

The colored coating products can be applied to paper which may itself be white or colored by any conventional coating method used in the paper industry. Coated paper colored in accordance with the present invention has good lightfastness and excellent bleed resistance for, for example, water, alcohol, milk or soap. Due to the high affinity of these dyes for the filler, there are practically no characteristic migration effects on drying, and even if combinations of dyes are used, uniform dyeings are obtained.

Staining is performed with a high yield and minimal contamination of equipment and waste water. If a cationic dye is added to a coating product without it being completely absorbed by the filler, or if the product contains a filler dyed with a cationic dye that is insufficiently substantive, then the dye present in the dissolved state cause agglomeration and thickening of the product. The theological properties of the product can be adversely affected such that it is no longer possible to coat it and the stability of the product can be seriously reduced. The present invention does not have this drawback, which leads to excellent stability of the coating product as well as good fastness properties in the colored paper.

Paper colored according to the method of the invention can be bleached without difficulty, in contrast to paper coated with products containing pigment dyes. This is very important for reusing colored and coated waste paper.

Paper colored according to the present invention can be printed very well and is very suitable for copying papers in xerography.

In the following examples, all parts and percentages are parts by weight and percentages by weight, respectively.

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Example I

285.7 parts of a 35% dispersion of kaolin (English China Clay Ltd.) in water, containing 100 parts of 15 dry weight kaolin, was stirred at room temperature (20 ° C) and 10 parts of a 25% solution of the dye of formula 2, wherein Pc phthalocyanine and Et represent an ethyl group. After 2 minutes of dyeing, 1.5 parts of a dispersant based on sodium-20 polyaerylate (Polysalz R, BASF) was added, followed by 20 parts of a synthetic binder with 50% solids based on butadiene-styrene (Dow-Latex 620). The pH was adjusted to 8.5 with 25% ammonia. A deep turquoise blue coating product with a solids content of about 40% was thus obtained.

This product was applied with an ink knife, in an amount of 20 g of dry material per square meter. 2 applied to uncoated paper weighing 80 g / m.

Finally, the paper was dried in a convection dryer 30 at 105 ° C for 60 minutes.

A uniform and deep-colored coated paper product was thus obtained, with excellent wet fastness to water and alcohol, as well as good light fastness.

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Example II

Example I was repeated, however, using 10 parts of a 20% aqueous solution of the compound of formula 3 as a dye.

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Example III

100 parts of lime (Omyalite 90) was pasted with 185 parts of water and homogenized using a Roth disperser until a stable viscosity was obtained (10 minutes). Then, the dye mentioned in Example II (10 parts) was added as a 20 Z aqueous solution. After stirring for 5 minutes, 1 part of dispersant (Polysalz F) was added and after 2 more minutes the colored suspension was filtered.

The filter residue remained a deep blue color and the filtrate was almost colorless even after repeated washing with water. The product can be used in the manner described in Example I.

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Claims (19)

A colored paper coating product, characterized in that it contains an aqueous paste or dispersion of a filler, which is colored with a water-soluble, polycionic dye, together with a binder. Coating product according to claim 1, characterized in that the filler is kaolin, calcium carbonate or talc. Coating product according to claim 1 or 2, 10, characterized in that the dye is biskationic. Coating product according to any one of the preceding claims, characterized in that the dye is a metal complex dye. Coating product according to claim 4, characterized in that the dye is a 1: 1 or 1: 2 metal complex azo dye. Coating product according to any one of the preceding claims, characterized in that the dye, as metal-free cation, has a molecular weight of at least 400. Coating product according to any one of the preceding claims, characterized in that the dye from an aqueous solution containing 1% dye, based on the weight of the filler, at a temperature between 20 and 90 ° C and without the use of dyeing aids, at least 90% is absorbed by the filler to an extent of 25. Coating product according to any one of the preceding claims, characterized in that the dye has a take-up ratio (ratio of the dye absorbed by the substrate to the total amount of dye in the bath) of 90-100 as defined by DIN 54000 or ISO RIOS / I 1959, part 1, when mercerized cotton for 90 minutes in a 83 0 1 1 5 6 β standard depth of 1/1 from a boiling aqueous, non-electrolyte, bath in a ratio of 20 : 1 is painted from liquid to material. Coating product according to any one of the preceding claims, characterized in that the dye is a phthalocyanine dye containing two or more cationic groups attached to the periphery of the phthalocyanine ring system. Coating product according to any one of claims 10 to 8, characterized in that the dye has a substantially linear structure and contains three or more homo or heteroaromatic rings or condensed ring systems which are directly or via bridging groups connected such that two terminal rings or ring systems and one or more mid-placed rings or ring systems are present, with on average at least 1.3 cationic groups per molecule attached to the terminal rings or ring systems and no others elsewhere. Coating product according to claim 10, 20, characterized in that the dye contains a cationic group on each terminal ring or ring system and none elsewhere. Coating product according to any one of the preceding claims, characterized in that as dye a dye is described in published British patent applications 2,076,421A, 2,081,734A, 2,082.6I5A, British patent 2,019,873 or published European patent application. 41,040 applies. Coating product according to any one of the preceding claims, characterized in that it contains 0.1-10% by weight of a dispersant. Coating product according to claim 13, characterized in that the dispersant used is a condensation product of -naphthalene sulfonic acid and formaldehyde, which contains 35 units of the formula 1. 830 1 1 5 6 m Coating product described in any one of the preceding claims. 16. A filler selected from kaolin, calcium carbonate, talc, zinc white and titanium dioxide, dyed with a polycationic dye. 17. Colored filler described in Example III. 18. Method for producing colored coated paper, characterized in that a coating product according to any one of claims 1-15 is applied to paper 10. A colored paper product coated with a coating product according to any one of claims 1-15. 15 8301156 j @ t5j Γ Na OjS ”^ SOjNa fa» _ * Cu Pc - f CHiNE ^ Cl® ^ 2 © β> 0 — Cu-O NH (CH2) 3NH (CHj) a ClT SOj ^ XNH (CHe) aNH (CH!) t JS 3 8301156: SANDOZ AG in Basel, Switzerland