Disazo dyes, and copper complexes thereof, for dyeing paper

The present invention relates to dyes of formula

wherein

Z 1 is NHR 6 , R 6 being a radical of formula CO—R 8 , CO—NH—R 8 , SO 2 -alkyl, SO 2 -aryl,

COOR 8 ,

R 8 being hydrogen, alkyl or aryl and

R 7 being COOH or SO 3 H in the o-position to the NH 2 group,

Z 2 is as defined for Z 1 or is hydrogen, hydroxy, alkoxy or a radical NHR 5 ,

R 5 being hydrogen, alkyl, aryl, COR 8 , CO—NHR 8 or SO 2 R 8 ,

R 1 and R 3 are each independently of the other hydrogen, hydroxy, alkyl or alkoxy,

R 2 and R 4 are each independently of the other hydrogen, hydroxy, alkyl or alkoxy, halogen, sulfo, carboxy, NHCONHR 8 or NHCOR 8 ,

X is a direct bond in which case symmetrical compounds wherein Z 1 and Z 2 are NHCOCH 3 , NHCOOCH 3 or NHCO-phenyl are excluded, or is —C═C— in which case both Z 1 and Z 2 cannot simultaneously be acetylamino, benzoylamino or 4-amino-3-sulfo-anilino, or is azo, azoxy, —NR 8 , —NR 8 CONR 9 — or a group of formula

Y being hydroxy, alkoxy or NR 8 R 10 ,

R 9 and R 10 being each independently of the other hydrogen, unsubstituted or substituted alkyl or unsubstituted or substituted aryl,

n and m are each independently of the other 1 or 2,

and wherein the rings A and B may each independently of the other carry a fused-on benzene ring,

with the proviso that the compounds of formulae

are excluded.

The present invention relates also to mono- or bis-copper complexes of dyes of formula

wherein R 1 and/or R 3 are hydroxy or alkoxy and the other substituents are as defined for formula (1).

In this Application, the dyes are shown in the form of the free acid, but the corresponding salts, for example metal or ammonium salts, are also to be included.

In the dyes of formula (1), X is preferably azo, azoxy or —C═C—.

In this Application, halogen is generally fluorine, bromine or, especially, chlorine.

According to the invention, alkyl radicals are to be understood as being generally open-chain or branched or cyclic alkyl radicals, preferably containing from 1 to 8 carbon atoms, for example methyl, ethyl, n- or iso-propyl, n-, sec- or tert-butyl, n-hexyl, n-octyl, cyclopentyl and cyclohexyl.

Aryl is to be understood as being especially naphthyl or phenyl, each of which may be substituted by, for example, C 1 –C 4 alkyl, and more especially unsubstituted naphthyl or phenyl.

These alkyl radicals and also the cycloalkyl or aryl groups may be mono- or poly-substituted, for example by hydroxy, carboxy, halogen, cyano, amino or C 1 –C 4 alkoxy.

The alkoxy radicals may have from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms and are, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentyloxy and n-hexyloxy. The alkoxy groups also may be substituted, for example by the radicals listed as possible substituents for the alkyl groups, especially by hydroxy or C 1 –C 4 alkoxy.

In the dyes of formula (1) and copper complexes thereof, Z 2 is preferably hydrogen, hydroxy, alkoxy, amino, NH—COO—C 1 –C 4 alkyl, or anilino which is unsubstituted or substituted by amino and/or by sulfo.

Z 1 is preferably NH—COO—C 1 –C 4 alkyl or the 4-amino-3-sulfo-anilino radical.

R 2 and R 4 are preferably hydrogen, C 1 –C 4 alkyl or C 1 –C 4 alkoxy.

In especially preferred dyes, Z 1 and Z 2 are identical and each is NH—COO—C 1 –C 4 alkyl or the 4-amino-3-sulfo-anilino radical.

The dyes of formula (1) are prepared in a manner known per se, for example a diamine of formula

is tetraazotised in known manner and coupled with 2 moles of a coupling component of formula

or with 1 mole each of a coupling component of formula (4) and a coupling component of formula

under conditions known per se.

It is also possible first to prepare the monoazo compounds of formulae

and to react 2 moles of a compound of formula (6) or 1 mole of a compound of formula (6) and 1 mole of a compound of formula (7) with a compound U—X—U′, QH and Q′H in each case being a group which can be replaced with a bridging member of formula X with removal of UH and U′H, respectively.

Such reactions have been described many times in the literature for the preparation of bridged disazo dyes.

When X is an azoxy group, the corresponding compounds of formula (1) can also be prepared in a manner likewise known per se by diazotisation of unsubstituted or substituted p-nitroanilines, coupling with a coupling component of formula (4) and/or (5) and subsequent reduction, for example using glucose.

The dyes of formula (1) which contain a free amino group can, in many cases, be prepared in pure form only with difficulty. An improvement can be achieved by introducing a protecting group which is subsequently removed. That is the case especially for those dyes wherein X is azoxy. Suitable protecting groups are those that are readily removable and that are stable under the conditions of the basic azoxy condensation. An alkoxycarbonyl group, especially the ethoxycarbonyl group, is especially suitable.

The mono- or bis-copper complexes of dyes of formula (2) are obtained in a manner known per se by means of copper-treatment of the customarily prepared dyes of formula (1) using copper-yielding agents in amounts of from 1 to 2.5 moles of copper per mole of dye of formula (1). The copper-treatment can also be carried out by demethylation as a result of cleavage of an alkoxy group or oxidatively with introduction of an additional oxygen group.

The invention preferably relates to the mono-copper complexes of dyes of formula (2) and mixtures thereof with the bis-copper complexes of such dyes.

These are obtained in a manner known per se by means of copper-treatment of the conventionally prepared dyes of formula (2) using copper-yielding agents in amounts of from 1 to 1.5 moles of copper per mole of dye of formula (2).

Depending upon the nature of the bridging member X, it is also possible for one of the halves of the dye of formula (2) that are connected by X to be reacted with up to 1 mole of copper-yielding agent and then to be connected to the second, non-copper-treated half by a direct bond or via the bridging member X. It is preferred, however, to start from the dye of formula (2) and to react that dye with a copper-yielding agent.

The dyes of formula (1) and the mono- and bis-copper complexes of dyes of formula (2) are suitable for dyeing natural and synthetic material.

The material is, for example, fibre material of leather, wool, polyamide, glass fibres or cotton and, especially, paper.

Using customary dyeing methods, blue dyeings having good fastness properties are obtained on such materials. Dyeings using the copper complexes especially have excellent light-fastness properties. The shade and the light-fastness can be controlled by the amount of copper used. When preparing mixtures of the mono-copper complexes with the bis-copper complexes, the amount of free copper in the effluents from synthesis can be reduced to a value of under 100 ppm whilst still obtaining good light-fastness properties.

The invention relates also to the use, for dyeing paper, of dyes of formula

wherein

Z′ 1 is NHR 6 , R 6 being a radical of formula CO—R 8 , CO—NH—R 8 , SO 2 -alkyl, SO 2 -aryl,

COOR 8 ,

R 8 being hydrogen, alkyl or aryl and

R 7 being COOH or SO 3 H in the opposition to the NH 2 group,

Z′ 2 is as defined for Z′ 1 or is hydrogen, hydroxy, alkoxy or a radical NHR 5 ,

R 5 being hydrogen, alkyl, aryl, COR 8 , CO—NHR 8 or SO 2 R 8 ,

R 1 and R 3 are each independently of the other hydrogen, hydroxy, alkyl or alkoxy,

R 2 and R 4 are each independently of the other hydrogen, hydroxy, alkyl or alkoxy, halogen, sulfo, carboxy, NHCONHR 8 or NHCOR 8 ,

X Is a bridging member or a direct bond,

n and m are each independently of the other 1 or 2,

and wherein the rings A and B may each independently of the other carry a fused-on benzene ring, it not being possible for both Z′ 1 and Z′ 2 simultaneously to be acetylamino or benzoylamino when X is a bridging member of formula —C═C—, and with the proviso that the compound of formula

is excluded.

The dyes of formula (1) and the copper complexes of dyes of formula (2) or the mixtures of mono-copper complex with the bis-copper complex are preferably used as solid or liquid commercial forms.

In the form of powder or granules, the dyes are used especially in discontinuous mass dyeing, the dyes being added usually in the form of a stock solution to the pulper, hollander or mixing vat. In this case dye preparations are preferably used which may also comprise, besides the dye, diluents, e.g. urea as solubiliser, dextrin, Glauber's salt, sodium chloride and dispersants, dusting agents and sequestrants, such as tetrasodium phosphate.

The invention accordingly relates also to solid dye preparations for dyeing paper, which preparations comprise a dye of formula (1) according to the invention or a mono- or bis-copper complex of a dye of formula (2).

In recent years, the use of concentrated aqueous solutions of dyes has gained in importance, specifically because of the advantages which such solutions have over dyes in powder form. By using solutions, the difficulties associated with the formation of dust are avoided and the users are freed from the time-consuming and often difficult dissolution of the dye powder in water. The use of concentrated solutions has been prompted furthermore by the development of continuous dyeing processes for paper, since in those processes it is advantageous to add the solution in metered amounts directly to the pulp flow or at any other suitable point in the paper-making.

The invention accordingly relates also to concentrated aqueous solutions of the dyes of formula (1) used in accordance with the invention or of the mono- or bis-copper complexes of dyes of formula (2) for dyeing paper, which solutions contain from 5 to 30% by weight of dye, based on the total weight of the solution.

The concentrated solutions may comprise further auxiliaries, for example solubilisers, such as ε-caprolactam or urea, organic solvents, such as glycols, polyethylene glycols, dimethyl sulfoxide, N-methylpyrrolidone, acetamide, alkanolamines or polyglycolamines.

The following Examples serve to illustrate the invention but do not limit the invention thereto. Parts and percentages relate to weight, unless otherwise indicated.