Colorant mixture

Details Colorant mixture Colorant mixture

2001-07-03

2003-07-22

Klemanski, Helene (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Marking

C008S641000

Reexamination Certificate

active

06596067

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to the field of colorants, especially for use in recording fluids for writing and recording instruments, for example for ink-jet processes.
By ink-jet process is meant a recording system where droplets of ink are sprayed from a small nozzle onto a recording material, for example paper, under electronic control. The applied ink droplets adhered on the recording material and so depict the desired information. In practice, two methods are used today for generating and directing the ink droplets: the continuous stream process, in which a continuous spray of ink droplets is produced, the unneeded droplets being deflected into reservoir vessel for recycling, and the drop-on-demand process, where ink droplets are produced only when actually needed for writing. Generation of droplets may be effected by briefly raising the pressure, for example by means of a piezo crystal, in an ink chamber equipped with a small nozzle. There are also systems where the spray of ink droplets is produced by supplying thermal energy.
Regardless of the operating principle underlying an ink-jet recording system, the ink used has to meet certain requirements. The ink composition has to have carefully harmonized physical properties such as surface tension, viscosity and electrical conductivity to render it suitable for generating the droplets and controlling their direction of flight. Another important requirement is that the ink may not form any solids, even on evaporation of any constituent of the recording fluid or when the chemical composition of the ink changes during storage, during recording or during a recording pause. Furthermore, the image once recorded shall possess high water resistance, lightfastness and abrasion resistance (EP-A-0 823 233 and U.S. Pat. No. 5,188,664). Prior art inks, especially aqueous inks, however, have the disadvantage of tending to smudge on the recording material when they are moistened. A further disadvantage is that prior art inks usually fade quickly on exposure to light or mechanical abrasion.
Considering ink formulation requirements for multicolor printing, an additional problem is that the dyes used in the inks must correspond very exactly to the three color primaries yellow, magenta and cyan. The choice of suitable dyes is constrained not only by the hue needed, but also by the necessary cleanness of hue and the desire for brilliant color reproduction. Hitherto it has not been possible to develop an ink composition that possesses all the desired properties to the ideal degree and can be successfully used in commercial practice. Take magenta inks as an example. Conventional inks based on water-soluble magenta dyes utilize for example direct dyes, such as C.I. Direct Red 1, 11, 37, 62, 75, 81, 87, 89, 95 and 227. Inks prepared from direct dyes have excellent water resistance owing to the substantivity of direct dyes, but also two disadvantages: the nozzles tend to become clogged with precipitated dye during continuous printing or in intermittent use because of the low solubility in water. Secondly, aggregation is increasingly observed, which leads to dull hues and hence to unsatisfactory color reproduction.
On the other hand, the use of acidic dyes, for example C.I. Acid Red 1, 8, 52, 87, 94, 115, 131, 144, 152, 154, 186 and 245, has also been investigated, with the result that good color reproduction is indeed achieved, but the durability of the printed images is poor because of the low light and water resistance.
DE-A-3 614 462 and DE-A-3 320 373 disclose recording fluids which may contain reactive dyes. However, prints with water-soluble reactive dyes of the chlorotriazinyl or &bgr;-sulfatoethylsulfonyl type, however, usually do not possess optimal water resistance, an additional adverse effect being the formation of chloride or sulfate ions through hydrolysis of the reactive groups.
As well as dyes, ink-jet ink colorants also include highly lightfast pigments, for example C.I. Pigment Red 122, C.I. Pigment Red 176, C.I. Pigment Red 184, 185 or C.I. Pigment Red 269. The disadvantage is that the prints obtained lack brilliance.
There is consequently a need for improved recording fluids which are superior to prior art magenta inks especially in hue, storage stability and water resistance and also have the other properties required for the ink-jet art.
SUMMARY OF THE INVENTION
It has been found that, surprisingly, the stated requirements are met on using the hereinbelow defined water-soluble dyes of the formulae (1) and (2) as mixtures.
The present invention provides a dye mixture consisting essentially of C.I. Acid Red 289 of the formula (1) and a compound of the formula (2) in a weight ratio of 1:100 to 100:1, based on dry weights,
where
x is SO
2
R
1
,
Y is H, alkyl, alkoxy, preferably H, (C
1
-C
4
)-alkyl, (C
1
-C
4
)-alkoxy;
R
1
is OH, CH═CH
2
, CH
2
CH
2
OR
2
, CH
2
CH
2
NR
3
R
4
and CH
2
CH
2
SR
5
,
R
2
is H, SO
3
M or (C
1
-C
6
)-alkyl, which may be substituted by one or more, for example 1, 2 or 3, substituents selected from the group consisting of OH, NH
2
, COOM and SO
3
M;
R
3
and R
4
are independently H, (C
1
-C
6
)-alkyl, which may be substituted by one or more, for example 1, 2 or 3, substituents selected from the group consisting of OH, NH
2
, COOM and SO
3
M, (C
1
-C
6
)-acyl, C
6
-C
10
-aryl or halogen-substituted C
6
-C
10
-aryl;
R
5
is (C
1
-C
6
)-alkyl, which may be substituted by one or more, for example 1, 2 or 3, substituents selected from the group consisting of OH, NH
2
, COOM and SO
3
M, (C
1
-C
6
)-acyl, C
6
-C
10
-aryl or halogen-substituted C
6
-C
10
-aryl;
M1 is Cu, Co, Ni, Fe, Cr or ⅔ Al; and
M is hydrogen, a monovalent metal cation, one equivalent of a polyvalent metal cation or an ammonium ion which may be substituted by (C
1
-C
4
)-alkyl, (C
1
-C
4
)-alkoxyalkyl or hydroxy-(C
1
-C
4
)-alkyl.
M is preferably hydrogen, sodium or potassium.
M1 is preferably Cu.
The compound of the formula (2) where SO
2
R
1
is meta to the azo linkage and Y is H and also where R
1
is &bgr;-sulfatoethyl and M1 is Cu, is known as C.I. Reactive Red 23.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preference for the purposes of the present invention is given to a mixture of C.I. Acid Red 289 and C.I. Reactive Red 23.
Preferred mixing ratios, based on dry weights, are between 1:10 and 10:1, especially between 1:4 and 4:1.
The dye mixture of the invention may additionally contain a shading colorant, preferably selected from the group consisting of C.I. Direct Red 1, 11, 37, 62, 75, 81, 87, 89, 95, 227; C.I. Acid Red 1, 8, 52, 87, 94, 115, 131, 144, 152, 154, 186, 245 and 249; C.I. Pigment Red 122, 176, 184, 185 and 269. The shading colorant is preferably present in an amount of 0.001 to 5% by weight, especially 0.01 to 1% by weight, based on the dry weight of the total mixture.
A possible process for preparing the dye mixture of the invention comprises the dyes of the formulae (1) and (2) and optionally the shading colorant being mixed with each other in the stated mixing ratios, in powder form, in dissolved form, in the form of a water- or solvent-moist presscake or in the form of a masterbatch.
Dyes of the formula (2) are preparable as described in as yet unpublished German patent application 101 06 682.1.
The dyes may also be prepared by the continuous mixing of equivalent amounts of the starting materials in the form of aqueous acidic or aqueous alkaline solutions in for example mixing nozzles and continuous reactors with or without a supplementary reaction phase in a reaction vessel.
The present invention also provides for the use of the disclosed mixtures for dyeing and printing natural and synthetic fiber materials (e.g. polyester, silk, wool, blend fabrics), especially for recording script and images on various recording media, and also for coloring paper or celluloses in the pulp.
For use in recording fluids, the described dyes are worked up in a manner appropriate to the stated requirements. The dyes may be isolated from the initially obtained, preferably aqueous, reaction mixtures b

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