Abstract:
Paper is colored by a process in which a compound which, in the form of the free acid, is of the formula I ##STR1## where, in each case independently of one another, A is unsubstituted or methyl substituted C 1  -C 6  -alkylene or vinylene, 
     R is each hydrogen or C 1  -C 4  -alkyl, 
     X is each --CO-- or --SO 2  --, 
     K is each a cationic group and 
     Y is hydrogen, chlorine or bromine.

Description:
This application is a continuation of application Ser. No. 895,935, filed on Aug. 13, 1986, now abandoned. 
    
    
     SUMMARY OF THE INVENTION 
     The present invention relates to a process for coloring paper, wherein a compound which, in the form of the free acid, is of the general formula I ##STR2## where, in each case independently of one another, the radicals 
     A are each unsubstituted or substituted C 1  -C 6  -alkylene or vinylene, the radicals 
     R are each hydrogen or C 1  -C 4  -alkyl, the radicals 
     X are each --CO-- or --SO 2  --, and the radicals 
     K are each a cationic group and 
     Y is hydrogen, chlorine or bromine, is used. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Specific examples of radicals A are ##STR3## 
     R may be CH 3 , C 2  H 5 , C 3  H 7  or C 4  H 9 , but is preferably hydrogen. 
     X is preferably --CO--. 
     Particularly suitable basic or cationic radicals are amino, hydrazine and hydroxylamino groups, which may furthermore be quaternized. These are, in particular, the groups ##STR4## in which R 1  to R 4  independently of one another are each unsubstituted or OH-substituted C 1  -C 4  -alkyl, R 5  and R 6  independently of one another are each C 1  -C 4  -alkyl, R 7  is hydrogen, C 1  -C 4  -alkyl which is unsubstituted or substituted by hydroxyl, phenyl or carbamyl, or phenyl or cyclohexyl which is unsubstituted or substituted by 1, 2 or 3 methyl groups, R 8  is hydrogen or C 1  -C 4  -alkyl which is unsubstituted or substituted by hydroxyl, phenyl or carbamyl, R 1  and R 2  or R 3  and R 4  or R 7  and R 8  together with the common N atom may form a pyrrolidine, piperidine, morpholine or piperazine ring, and R 3 , R 4  and R 5  together with the common N atom may form an unsubstituted or alkyl-substituted imidazoline or pyridinium ring or a radical of the formula ##STR5## Where K is a cationic hydrazine radical of the formula ##STR6## R 1  and R 2  independently of one another are each alkyl of 1 to 4 carbon atoms. The alkyl radicals may be unsubstituted or substituted by hydroxyl or, together with the common nitrogen atom, may form a pyrrolidine, piperidine, morpholine or piperazine ring. Examples of suitable radicals are: ##STR7## Where K is a group of the formula ##STR8## R 3 , R 4  and R 5  independently of one another are each alkyl of 1 to 4 carbon atoms, and R 3  and R 4  may furthermore be substituted by phenyl or hydroxyl. R 3  and R 4 , likewise with the common N atom, may form a pyrrolidine, piperidine, morpholine or piperazine ring. 
     Examples of suitable cationic groups of this type are: ##STR9## Where K is a cationic hydroxylamino radical of the formula ##STR10## R 1  and R 2  have the meanings stated above. R 6  is alkyl of 1 to 4 carbon atoms. Examples of cationic hydroxylamino radicals are: ##STR11## 
     Finally, K may furthermore be an amino group of the formula ##STR12## 
     In this group, R 7  and R 8  are each hydrogen or alkyl of 1 to 4 carbon atoms, and alkyl may furthermore be substituted by hydroxyl, phenyl or carbamyl. R 7  may furthermore be cyclohexyl which is unsubstituted or substituted by 1, 2 or 3 methyl groups, or may be phenyl. Finally, R 7  and R 8 , together with the common N atom, may form a pyrrolidine, piperidine, morpholine or piperazine ring. Examples of amino groups of this type are: ##STR13## 
     In addition to these basic or cationic radicals, K may furthermore be a radical of a basic or cationic polyamine. 
     Examples of polyamine radicals from the large number of possible ones are: ##STR14## 
     Where K is a cationic group, the azo compounds of the formula I are in the form of their inorganic or organic salts. 
     Suitable counter-ions are both inorganic and organic anions, eg. methylsulfate, aminosulfate, benzenesulfonate, naphthalenesulfonate, oxalate, maleate, formate, acetate, hydroxyacetate, methoxyacetate, propionate, lactate, succinate, tartrate, methanesulfonate and benzoate. 
     Examples of preferred anions are formate, acetate, hydroxyacetate, methoxyacetate, lactate, aminosulfate and methanesulfonate. 
     In the azo compounds of the formula I, the sulfonic acid groups may furthermore form an internal salt with one of the cationic groups K. 
     The dyes of the formula I are synthesized by the methods described in German Patent 1,135,589 or 1,266,898 or by methods similar to these. 
    
    
     The examples which follow illustrate the preparation. 
     Parts and percentages are by weight, unless stated otherwise. 
     The azo compounds of the formula I are used either as powder preparations or granules or in the form of concentrated solutions. Powder preparations are standardized in a conventional manner with standardizing materials, such as sodium sulfate, phosphate or acetate, in the presence of dust inhibitors, or the azo compounds are introduced commercially directly in the form of spray-dried preparations. Concentrated dye solutions may be of an aqueous or aqueous/organic type, conventional, very readily degradable additives being preferred, such as organic acids, preferably acetic acid, methoxyacetic acid, methanesulfonic acid, formic acid, lactic acid or citric acid, amides, such as formamide, dimethylformamide or urea, alcohols, such as glycol, diglycol and diglycol ethers, preferably the methyl or ethyl ether. 
     According to the invention, the azo compounds of the formula I are particularly suitable as dyes for coloring and printing paper by a conventional method. The azo compounds are preferably used for coloring and printing paper, semicardboard and cardboard in the pulp and for surface coloring. 
     They are suitable for all types of papers, especially bleached, unsized and sized lignin-free paper; bleached or unbleached pulp can be used as a starting material, and hard wood or soft wood pulp, such as birch and/or pine sulfite and/or sulfate pulp may be employed. These compounds are very particularly useful for coloring unsized paper (eg. napkins, tablecloths, hygienic papers), because of their great affinity to this substrate. 
     The novel azo compounds of the formula I are readily absorbed by these substrates, the effluent being virtually colorless. 
     The colorations obtained possess good allround fastness, such as comparatively good lightfastness coupled with great clarity and depth and good wetfastness, ie. they have no tendency to bleed when colored paper in the wet state is brought into contact with moist white paper. Moreover, they have good fastness to alumn, acids and alkalis. The hue of the colorations is not altered by fillers such as kaolin and talc. 
     The high affinity for paper and the high absorption rate of the novel dyes is very advantageous for the continuous coloring of paper. 
     The colored papers can very readily be bleached, both with chlorine bleaches and with hydrosulfite bleaches. 
     Of particular importance are compounds of the formula I a ##STR15## where 
     A 1  and A 2  independently of one another are each CH 2  or C 2  H 4  and 
     K 1  and K 2  have the meanings stated for K. 
     Examples of preferred radicals K are: ##STR16## 
     The present invention furthermore relates to novel compounds of the formula I in which one or both of the radicals K is a nicotinamide radical. 
     EXAMPLE 1 
     70 parts of chemically bleached sulfite pulp (from soft wood) and 30 parts of chemically bleached sulfite pulp (from birch wood) in 2000 parts of water are beaten in a beater. 
     0.2 part of the dye of the formula ##STR17## is sprinkled into this pulp. 
     This pulp is mixed for 20 minutes and then converted to paper. The absorptive paper obtained in this manner has a yellowish-red color. The effluent is virtually colorless. The paper can very readily be bleached and has good lightfastness and fastness to bleeding. 
     Similar results are obtained if the dye is replaced by a dye from the table below. 
     
              Formula Ia  ##STR18##  A.sup.1 A.sup.2 K.sup.1 K.sup.2 Hue  ##STR19##  2 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR20##  ##STR21##  red  3 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR22##  ##STR23##  red  4 4 4 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR24##  ##STR25##  red  5 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR26##  ##STR27##  red  6 4 6 CH.sub.2CH.sub.2 CH.sub.2 ##STR28##  ##STR29##  red  ##STR30##  7 4 6 CH.sub.2 CH.sub.2CH.sub.2 ##STR31##  ##STR32##  red  8 3 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR33##  ##STR34##  orange  9 4 7 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR35##  ##STR36##  bluish-red  10   4 7 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR37##  ##STR38##  bluish-red 
    
     EXAMPLE 11 
     25 kg of catalog paper (waste), 60 kg of bleached groundwood (65° Schopper Riegler) and 15 kg of unbleached sulfite pulp in 2500 l of water are beaten in a pulper. 0.4% of soluble starch, 16% of kaolin and 2% of talc (based on dry fiber) are added to the 4% strength aqueous stock suspension, and the latter is then beaten to 45° Schopper Riegler in a refiner. 12 kg of a 10% strength solution of the dye of the formula ##STR39## are added to the stock suspension, the said solution containing acetic acid. This corresponds to 1%, based on absolutely dry fiber, of dry red dye. After an absorption time of 15 minutes, a resin size dispersion is added to the stock, in an amount corresponding to 0.6%, based on fiber, of dry resin size. After 10 minutes, the stock flowing out of the mixing chest is diluted continuously with water to a consistency of 0.8% and brought continuously with alum [Al 2  (SO 4 ) 3 .18H 2  O] to pH 4.5 (measured in the backwater), and pumped into the headbox. Yellowish-red catalog paper (60 g/m 2 ) having good lightfastness and fastness to water is obtained. The manufacturing wastes can readily be bleached with chlorine bleaches. 
     Using the dyes in the table below instead of the above dye gives red to orange paper which has good fastness properties and can readily be bleached with chlorine bleaches. 
     
              Formula Ia  ##STR40##  ##STR41##  A.sup.1 A.sup.2 K.sup.1 K.sup.2 Hue      12 4 6 CH.sub.2 CH.sub.2  ##STR42##  ##STR43##  red  13 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR44##  ##STR45##  red  14 4 6 CH.sub.2CH.sub.2 CH.sub.2 ##STR46##  ##STR47##  red  15 4 6 CH.sub.2 CH.sub.2CH.sub.2 ##STR48##  ##STR49##  red  16 4 6 CH.sub.2 CH.sub.2 ##STR50##  ##STR51##  red  17 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR52##  ##STR53##  red  18 4 6 CH.sub.2 CH.sub.2CH.sub.2 ##STR54##  ##STR55##  red  19 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR56##  ##STR57##  red  20 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR58##  ##STR59##  red  21 4 6 CH.sub.2CH.sub.2 CH.sub.2 ##STR60##  ##STR61##  red  22 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR62##  ##STR63##  23 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR64##  ##STR65##   24 4 6 CH.sub.2CH.sub.2 CH.sub.2  CH.sub.2 ##STR66##  ##STR67##  25 4 6 CH.sub.2CH.sub.2 CH.sub.2CH.sub.2 ##STR68##   26 4 6 CH.sub.2CH.sub.2 CH.sub.2  CH.sub.2 ##STR69## 
    
     EXAMPLE 27 
     15 kg of mechanical waste paper, 25 kg of bleached groundwood and 10 kg of unbleached sulfate pulp are beaten to a 3% strength aqueous stock suspension in a pulper. The stock suspension is diluted to 2% strength in a dyeing vat. 0.5% of soluble, oxidatively degraded corn starch, 5% of kaolin and 1.25 kg of a 5% strength solution of the dye of the formula ##STR70## which solution contains acetic acid, are then added in succession to this suspension, while stirring, the percentages being based on total dry fibers. After 20 minutes, 1%, based on absolutely dry fiber, of a resin size dispersion is added to the stock in the mixing chest. The homogeneous stock suspension is brought to pH 5 with alum on the paper machine, just upstream of the headbox. 
     An 80 g/m 2  machine finished bag paper which has a red hue, good fastness to bleeding according to DIN 53,991 and good lightfastness is produced on the paper machine. 
     EXAMPLE 28 
     A 10% strength solution of the dye ##STR71## in water is applied to a 95×150 mm gravure printing plate by means of a rubber blade. A bleached tissue paper is placed on the gravure printing plate, covered with a non-absorptive paper and rolled with a steel roller weighing 20 kg. The tissue paper provided with a red print is dried. 
     The print has good lightfastness and fastness to water.