Process for dying leather with pigments and cationic binders

Specific cationic polymers having hydrophobic side chains are highly suitable as binders for pigments for the dyeing of leather.

The invention relates to cationic pigment binders which can be used in 
aqueous systems for the pigmenting of leather. 
The dyeing of leather with dyestuffs often results in defects, such as, for 
example, poor light fastness or unsatisfactory dyeing of grains. The use 
of pigments for the pigmenting of leather often gives non-uniform 
pigmenting: 
The pigments are preferentially deposited on the flesh side and on open 
grain damages of the leather. The pores (at the roots of the hair) often 
remain undyed. However, for many types of leathers, for example upholstery 
leather, garment leather or special shoe upper leathers, complete 
penetration is required. 
In this context, it is of importance that the pigment dispersion be 
sufficiently stable for enabling uniform distribution of the pigments in 
and on the leather; if, in contrast, upon contact of the dispersion with 
the leather surface the pigment precipitates, the pigment distribution 
obtained is, viewed over the leather cross section, unsatisfactory. 
Moreover, an excessively high pigment concentration on the leather surface 
leads to reduced adhesion of the finish. 
EP-A 344,555 discloses a process for the pigmenting of leather with 
pigments from an aqueous liquor in the presence of an alkoxylated 
polyamine containing at least 20 C atoms. The alkoxylated polyamines 
recommended in EP-A 344,555 are difficult to fix on leather and thus end 
up in part in the wastewater together with the wash liquors. 
A process for the pigmenting of leather with the pigments from an aqueous 
liquor has now been found which is superior to the hitherto known dyeing 
processes. The essential feature of this process is that a cationic 
polymer containing neutralised tertiary amino groups and/or quaternary 
ammonium groups is used as pigment binder. 
Accordingly, the invention provides for the use of cationic polymers 
obtainable by polymerisation of 
a) 5 to 60, preferably 10 to 50, % by weight of N,N-C.sub.1 -C.sub.4 
-dialkylamino-C.sub.1 -C.sub.6 -alkyl acrylate and/or N,N-C.sub.1 -C.sub.4 
-dialkylamino-C.sub.1 -C.sub.6 -alkyl methacrylate and/or N,N-C.sub.1 
-C.sub.4 -dialkylamino-C.sub.1 -C.sub.6 -alkylacryl- and/or 
-methacrylamides, such as, for example, N,N-dimethylaminoethyl 
(meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, 
N,N-dimethylaminopropyl (meth)acrylamide, 
b) 0 to 90, preferably 5 to 60, % by weight of ethylenically unsaturated 
compounds which are free of amino and ammonium groups and whose 
homopolymers (at a number average molecular weight of at least 10,000) 
possess glass-transition temperatures of at least 90.degree. C., such as, 
for example, methyl methacrylate and/or acrylo- and/or methacrylonitrile 
and/or styrene and/or .alpha.-methylstyrene and/or p-methylstyrene and/or 
p-chlorostyrene, 
c) 0 to 70, preferably 0 to 50, % by weight of ethylenically unsaturated 
compounds which are free of amino and ammonium groups and whose 
homopolymers (at a number average molecular weight of at least 10,000) 
possess glass-transition temperatures below 90.degree. C., preferably 
below 50.degree. C., such as, for example, C.sub.1 -C.sub.22 -alkyl 
acrylates and/or C.sub.1 -C.sub.22 -alkyl methacrylates with the exception 
of methyl methacrylate, and 
d) 0 to 40, preferably 3 to 30, % by weight of monoethylenically 
unsaturated compounds which are free of amino and ammonium groups and have 
an average molecular weight (number average) of 400 to 6,000 and a water 
solubility below 1 g/l at 25.degree. C., 
the percentages given being based on the sum of components a) to d), 
followed by neutralisation and/or quaternisation, as pigment binders. 
Particularly preferably used polymers are those obtainable from 
I. 10 to 60, preferably 10 to 50, % by weight of component a) and 40 to 90, 
preferably 50 to 90, % by weight of component b), or 
II. 5 to 60, preferably 10 to 50, % by weight of component a), 5 to 70, 
preferably 10 to component b) and 
to 40, % by weight of 5 to 50, preferably 5 component c), monomers c) 
containing at least 8 C atoms in the alcohol radical, or III. 5 to 60, 
preferably 10 to 50, % by weight of component a), 10 to 70, preferably 10 
to 60, % by weight of component b) and 3 to 30 % by weight of component 
d). 
The amino groups of monomers a), after being neutralised or quaternised in 
the finished polymer, make it water-dispersible. If less than 10% by 
weight of these components, relative to total monomers, is used, aqueous 
dispersions having a relatively small amount of polymer dissolved in the 
form of a molecular dispersion are obtained. Higher proportions of 
component a) lead to increasing amounts of polymer dissolved in the form 
of a molecular dispersion until, at proportions of more than about 25% by 
weight, the amounts of polymer dissolved in the form of a colloid 
dispersion finally disappear altogether. 
Monomers b) make the polymer rigid, while monomers c) make it flexible. 
Compounds d) contain 1 terminal C.dbd.C double bond per molecule. Polymers 
containing radicals of compounds c) and d) incorporated therein are 
particularly preferred. The combination of a hydrophilic chain backbone 
and hydrophobic side chains results in surfactant-like properties which 
upon copolymerisation of compounds d) are transferred therefrom to the 
polymer to be used according to the invention. 
Several methods are available for preparing compounds d), for example 
1. free-radical polymerisation of vinyl monomers, such as, for example, 
styrene, acrylates, methacrylates, and the like, in the presence of 
mercapto-C.sub.2 -C.sub.6 -carboxylic acid, preferably 
.alpha.-mercaptoacetic acid, as chain transfer agent, followed by reaction 
of the resulting terminal carboxyl groups with compounds containing both a 
reactive epoxy group and an ethylenically unsaturated group, such as, for 
example, glycidyl acrylate, glycidyl methacrylate or allyl glycidyl ether 
(references: T. Corner, Adv. Polym. Sci. 62, p. 95-142 (1984) and Y. 
Tsukahara et al., J. Polym. Sci. Part A: Polym. Chem. 27, p. 1,099-1,114 
(1989)); 
2. free-radical polymerisation of C.sub.1 -C.sub.6 -alkyl methacrylates in 
the presence of cobalt complexes, preferably of diacetyl dioximes or based 
on porphin, as regenerable chain-transfer agents (references: N. S. 
Enikolopyan et al., J. Polym. Sci., Polym. Chem. Ed. 19, p. 879-889 
(1981); R. A. Sanayei and K. F. O'Driscoll, J. Macromol. Sci. Chem. A26 
(8), p. 1,137-1,149 (1989) and A. A. Gridnev, Polymer Sci. USSR 31 (10) p. 
2,369-2,376 (1989)); 
3. cationic polyaddition of 6-caprolactone in the presence of 
hydroxyl-containing ethylenically unsaturated compounds, preferably 
hydroxy-C.sub.2 -C.sub.3 -alkyl acrylate and hydroxy-C.sub.2 -C.sub.3 
-alkyl methacrylate, by means of catalysts (preferably sulphonic acids, 
such as p-toluenesulphonic acid, methanesulphonic acid, and the like) 
(references: R. H. Young, M. Matzner, C. A. Pilato: "Ring-Opening 
Polymerizations: Mechanism of Polymerization of .epsilon.-Caprolacton" 
Chap. 11 "Ring-Opening Polymerization", T. Saegusa and E. Goethals (Ed.), 
Am. Chem. Soc., Washington, D.C., 1977); 
4. polycondensation of hydroxy-C.sub.6 -C.sub.24 -carboxylic acids (for 
example 12-hydroxystearic acid), reaction of the terminal hydroxyl groups 
with C.sub.1 -C.sub.24 -carboxylic acids, followed by reaction of the 
terminal carboxyl groups with compounds containing both a reactive epoxy 
group and an ethylenically unsaturated group, such as, for example, 
glycidyl acrylate, glycidyl methacrylate or allyl glycidyl ether 
(references: K. E. J. Barrett, Dispersion Polymerization in Organic Media 
(1975), J. Wiley & Sons, London, New York, Sydney, Toronto). 
The polymers can be prepared by polymerisation of compounds a) to c) or d) 
by customary methods, in particular by bulk, solution, aqueous emulsion or 
suspension polymerisation initiated by free radicals. 
The polymers are preferably prepared in organic solution. Continuous and 
batchwise polymerisation methods are possible. Of the batchwise methods, 
the batch method and, preferably, the feed stream addition method may be 
mentioned. In the feed stream addition method, the organic solvent is 
introduced by itself or together with a portion of the monomer mixture as 
the initial charge, heated to the polymerisation temperature, 
polymerisation is started by free radicals in the case of a monomer as the 
initial charge, and the remaining monomer mixture or the entire monomer 
mixture together with an initiator mixture is metered in over a period of 
1 to 10 hours, preferably 2 to 6 hours. If necessary, the mixture is then 
reactivated in order to take the polymerisation to a conversion of at 
least 99%. 
In this procedure, it is often advantageous to introduce a larger portion 
of compound d) as the initial charge, since its reactivity may be reduced 
owing to steric hindrance or incompatibility with the growing polymer 
chain. Examples of suitable organic solvents are aromatics, such as 
benzene, toluene, xylene, chlorobenzene, esters, such as ethyl acetate, 
butyl acetate, methylglycol acetate, ethylglycol acetate, methoxypropyl 
acetate, ethoxypropyl acetate, propylene glycol diacetate, ethers, such as 
butylglycol, tetrahydrofuran, dioxane, ethylglycol ether, ketones, such as 
acetone, methyl ethyl ketone, methyl isobutyl ketone, halogenoalkanes, 
such as methylene chloride or trichloromonofluoroethane. 
The polymerisation initiated by free radicals can be started by initiators 
whose free-radical half-lives at 80.degree. to 180.degree. C. are between 
0.01 and 400 minutes. In general, the reaction is carried out in the 
temperature range mentioned, preferably between 100.degree. and 
160.degree. C., under a pressure of 1 to 20 bar, the exact polymerisation 
temperature depending on the type of initiator. 
The initiators can be used in amounts of 0.05 to 6% by weight, relative to 
the total amount of monomers. Examples of preferred initiators are 
aliphatic azo compounds, such as azoisobutyronitrile, and peroxides, such 
as, for example, dibenzoyl peroxide, t-butyl perpivalate, t-butyl 2-ethyl 
perhexanoate, t-butyl perbenzoate, t-butyl hydroperoxide, di-t-butyl 
peroxide, cumene hydroperoxide and dicyclohexyl peroxydicarbonate and 
dibenzyl peroxydicarbonate. 
For regulating the molecular weight of the polymers, customary regulators 
can be used, such as, for example, n-dodecylmercaptan, t-dodecylmercaptan, 
diisopropyl xanthogen disulphide, di(methylenetrimethylolpropane) 
xanthogen disulphide and thioglycol. They can be added in a maximum amount 
of 3% by weight, relative to the total amount of monomer. After 
polymerisation is complete, the polymers are converted into an aqueous 
solution or dispersion. To this end, the organic polymer solution is 
introduced into a water phase which in most cases is preheated and at the 
same time the organic solvent is removed by distillation, in general under 
reduced pressure. In order to achieve good water solubility or 
dispersibility, a neutralising agent, such as, for example, an inorganic 
or organic acid, can be added to the water phase. Examples of inorganic 
acids are hydrochloric acid, sulphuric acid, nitric acid and phosphoric 
acid. Examples of organic acids are formic acid, acetic acid, lactic acid, 
fumaric acid, maleic acid, tartaric acid, oxalic acid. Formic acid and 
acetic acid are particularly preferred. 
Quaternisation can be effected by means of quaternising agents either in 
the organic phase or in the aqueous phase. Examples of suitable 
quaternising agents are (ar)alkyl halides, sulphuric esters, 
epihalogenohydrins and monoepoxides, in particular methyl chloride, methyl 
iodide, dimethyl sulphate, benzyl chloride, ethyl chloroacetate, 
bromoacetamide, propylene oxide, 1,2-butylene oxide and epichlorohydrin 
and epibromohydrin. If quaternisation is incomplete, the remaining amino 
groups are neutralised with additional acid, and the polymer is dissolved 
or dispersed in water. The polymers are used in the form of 10 to 50, 
preferably 15 to 40% strength by weight aqueous solutions and/or 
dispersions which in general exhibit a viscosity of 10 to 10.sup.5, 
preferably 20 to 10,000 mPa.s/23.degree. C. and a pH of 2 to 8, preferably 
4 to 6. 
The pigments can easily be dispersed within a very short period of time by 
means of the polymers to be used according to the invention by mixing the 
components, for example, by means of a dissolver, a rotor/stator mill, a 
bead mill or ball mill. The particle size of the milled pigments and the 
colour yield are very good. 
There is virtually no limitation on the pigments which can be incorporated 
in the polymers to be used according to the invention; they can be of 
inorganic or organic nature. Suitable organic pigments include, for 
example, those of the azo, anthraquinone, azoporphin, thioindigo, 
dioxazine, naphthalenetetracarboxylic acid or perylenetetracarboxylic acid 
series, phthalocyanines and sulpho- and/or carboxyl-containing calcium, 
magnesium or aluminium lakes of a large number of which are disclosed, for 
example, in Colour Index, 2nd Edition. Suitable inorganic pigments 
include, for example, zinc sulphides, titanium dioxides, ultramarine, iron 
oxides, nickel compounds and chromium compounds and carbon black. Cadmium 
sulphide, lead chromate or other pigments which are less suitable because 
of their environmental properties could of course also be used. In 
principle, precipitated dyestuffs are also suitable. Prior to their 
treatment with pigments, the leathers can be predyed with dyestuffs or, 
after the pigment treatment, crossdyed with pigments and dyestuffs. 
Pigment preparations containing the polymers to be used according to the 
invention can be used for the dyeing not only of wet blues but also of 
crust leathers and retanned leathers. The polymer serves as carrier for 
the pigment and as fixing agent, thus making the use of foreign fixing 
agents unnecessary. The efficient dispersing action of the polymers to be 
used according to the invention also enables a joint use of pigments of 
different densities. 
Colouring with pigments dispersed in the polymers to be used according to 
the invention can, for example, be effected in the following manner: 
Wet blue, retanned or wetted-back crust is brought to a pH of about 4 
(advantageously in 200 to 400% by weight of water at 35.degree. to 
45.degree. C.). Depending on the desired colour strength, 0.1 to 20% by 
weight (preferably 0.5 to 8% by weight) of pigment and polymer is then 
added, and the leather is drummed for 30 to 60 minutes. After a few 
minutes, the liquor starts to become clear; after 30 minutes at the 
latest, a clear residual liquor and level dyed leathers are obtained which 
additionally can be crossdyed. The individual dyeings of wet blue (which 
term also includes chrome velour) and crust are as follows: 
Wet Blue 
After a short washing period, pigment and polymer are added in a new liquor 
at a temperature of 20.degree. to 60.degree. C., preferably 30.degree. to 
50.degree. C., and a pH of 3.5 to 4.5. After a running time of 30 to 60 
minutes, 1 to 3% by weight of commercially available chrome tanning agent 
is added in the form of a powder and drumming of the leather is continued 
for 30 to 60 minutes. The liquor is then virtually clear. The leather is 
then neutralised, re-tanned, possibly crossdyed and fat-liquored, and 
dried by conventional methods. 
Crust Leather 
After customary wetting-back, the leather is thoroughly rinsed. 0.5 to 2% 
by weight of an anionic commercially available fat-liquoring agent is 
added in a new bath at a temperature of 30.degree. to 60.degree. C., 
followed by drumming for 30 to 60 minutes. The pH is then lowered to 3.5 
to 4.5 by means of formic acid. Before adding pigment and polymer, a 
treatment with 0.5 to 2% by weight of a cationic auxiliary for 5 to 15 
minutes has proved to be particularly advantageous. Pigment and polymer 
are then added, and drumming is continued for another 30 to 60 minutes. 
The liquor is then virtually clear. If desired, the leather is then 
acidified and rinsed. 
It is in principle possible to use the pigment preparations according to 
the invention for the dyeing of leathers which have been tanned by means 
of vegetable tanning agents; however, the dyeing method has to be adapted 
to the vegetable leather type. 
The leather is removed from the liquor and finished in a manner customary 
for this type of operation. Additional dyeing with soluble anionic 
dyestuffs before or after pigmentation is possible. 
The physical fastness properties, such as perspiration fastness, light and 
migration fastness, are excellent. The process achieves very good hiding 
of the defects on the rawhide which are usually natural in origin or 
produced as a result of preservation. 
Examples 1 to 13 describe the preparation of the polymer, Examples P1 to 
P17 that of the pigment preparations and A1 to A4 describe the 
applications. 
The percentages given in the examples which follow are by weight; ratios 
are by weight.

EXAMPLES 
Starting Materials 
Compound d1) 
1,140 g (10 mol) of .epsilon.-caprolactone and 65 g (0.56 mol) of distilled 
hydroxyethyl methacrylate are introduced into a 2-1 flask as the initial 
charge and stabilised with 200 ppm of ionol. 1.2 g (0.1% by weight) of 
p-toluene-sulphonic acid (containing 1 mol of water of crystallisation) 
are added to this mixture, and polymerisation is carried out at 50.degree. 
C. for 22 hours. The course of the reaction can be monitored by means of 
the refractive index. The reaction is then stopped with 6.3 ml of a 1N 
sodium methoxide solution, and the reaction mixture is poured onto a metal 
sheet to give a white, wax-like product. 
Compound d2) 
11 g of stearic acid, 209 g of 12-hydroxystearic acid and 50 g of xylene 
are introduced as the initial charge, nitrogen is then passed over this 
solution, and the mixture is heated to 100.degree. C. It is stirred until 
a homogeneous solution has been formed. A solution of 0.15 g of titanium 
tetrabutoxide in 5 g of xylene is then added, and 17 ml of water of 
reaction are removed via a water separator by increasing the reaction 
temperature to about 190.degree. C. The evaporated polyester sample has a 
molecular weight Mn of 1,200 g.times.mol.sup.-1, an OH number of 1.5 mg of 
KOH/g and an acid number of 43 mg of KOH/g. 200 g of the polyester thus 
obtained are heated to 50.degree. C. and combined with 17.4 g of glycidyl 
methacrylate, 300 mg of hydroquinone and 0.3 g of 
N,N-dimethylaminododecane in 40 g of xylene. The mixture is then heated to 
100.degree. C. and stirred for 22 hours. After this time, the acid number 
has dropped to 4.9 mg of KOH/g. Xylene is removed by distillation until a 
final concentration of about 75% is reached. The solution is cooled off 
and filtered. Concentration of the solution: 75.8%. 
Compound d3) 
250 g of n-butyl methacrylate are poured into a 500 ml three-neck flask, 50 
mg of 5, 10, 15, 20-tetrakis(4-methoxyphenyl)-21H,23H-porphine cobalt (II) 
complex are added, the flask is evacuated three times and aerated with 
nitrogen. It is then heated to 80.degree. C. and upon reaching this 
temperature 1 g of azoisobutyronitrile is added, and the mixture is 
stirred at 80.degree. C. for about 10 hours. The crude solution is freed 
from residual monomers at 70.degree. C. in a high vacuum (0.1 mbar). The 
molecular weight Mn determined by .sup.1 H NMR end group analysis is about 
5,500 g mol.sup.-1. 
Example 1 
10,075 g of methyl isobutyl ketone are introduced into a 40-1 autoclave as 
the initial charge. The autoclave is thoroughly flushed with nitrogen and 
then heated to 75.degree. C. At this temperature, a mixture of 4,187 g of 
N,N-dimethylaminoethyl methacrylate, 7,406 g of styrene and 4,508 g of 
acrylonitrile and a solution of 378 g of azoisobutyronitrile in 3,978 g of 
methyl isobutyl ketone are metered in over a period of 6 hours with the 
exclusion of air. The mixture is then additionally stirred for 1 hour and 
reactivated with a solution of 45 g of azoisobutyronitrile in 567 g of 
methyl isobutyl ketone. It is then stirred at 75.degree. C. for about 8 
hours. After polymerisation is complete, 1,435 g of acetic acid are 
metered in. 1,155 g of propylene oxide are then metered in over a period 
of about 15 minutes, and the mixture is stirred for about 1 hour. After 
this period, a further 1,739 g of acetic acid are added. 
About 63-l of deionised water are introduced into a 120-1 autoclave as the 
initial charge and heated to about 60.degree. C. The contents of the 40-1 
autoclave are then added to the aqueous initial charge and dissolved 
therein with stirring. The solvent methyl isobutyl ketone is then 
distilled off at reduced pressure. 
The concentration of the aqueous dispersion is 24.0% by weight, the pH is 
4.2 and the viscosity measured at 23.degree. C. is 100 to 150 mPa.s (the 
aqueous dispersion is a non-Newtonian fluid!). 
Examples 2 to 7 
200 g of methyl isobutyl ketone (I in Table 1) are introduced into a 2-1 
stirred flask equipped with gas inlet and outlet as the initial charge, 
nitrogen is then passed over the liquid, and the contents are heated to 
70.degree. C. Monomer mixtures II (see Table 1) and initiator solution III 
are simultaneously metered to the initial charge over a period of 3 hours. 
The mixture is then stirred for 2 hours and reactivated with initiator 
solution IV. Stirring is continued for 10 hours, and the mixture is then 
neutralised with V. 
2,000 g of deionised water (VI) are then introduced into a 4-1 flask as the 
initial charge, heated to 60.degree. C. to 70.degree. C., and the contents 
of the 2-1 flask are combined therewith. The organic solvent is distilled 
off under reduced pressure (about 200 mbar). The physicochemical data of 
the polymer solutions are listed in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Examples 2 3 4 5 6 7 
__________________________________________________________________________ 
I. Initial charge 
Methyl isobutyl 
200 g 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
ketone: 
II. Monomer mixture: 
N,N-dimethylamino- 
150 g 
200 g 
150 g 
200 g 
225 g 
250 g 
ethyl methacrylate: 
Styrene: 165 g 
135 g 
135 g 
105 g 
120 g 
105 g 
Acrylonitrile: 
110 g 
90 g 
90 g 70 g 
80 g 70 g 
Compound d1): 
75 g 75 g 
125 g 
125 g 
75 g 75 g 
III. Initiator 
solution: 
Azoisobutyronitrile: 
12.5 g 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
Methyl isobutyl 
250 g 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
ketone: 
IV. Reactivator 
solution: 
Azoisobutyronitrile: 
2.5 g 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
Methyl isobutyl 
ketone: 50 g .fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
V. Neutralising 
agent: 
Acetic acid: 
60 g 80 g 
100 g 
120 g 
90 g 100 g 
VI. Deionised water: 
2000 g 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
.fwdarw. 
Concentration: 
23.6% 
29.8% 
25.0% 
20.7% 
29.4% 
23.0 % 
pH: 5.0 5.1 4.7 5.1 5.6 5.5 
Viscosity at 23.degree. C. 
&lt;50 760 &lt;50 890 6330 6100 
(mPa .multidot. s): 
__________________________________________________________________________ 
Examples 8 and 9 
200 g of methyl isobutyl ketone (I in Table 2) are introduced into a 2-1 
stirred flask equipped with gas inlet and outlet as the initial charge, 
nitrogen is then passed over the liquid, and the contents are heated to 
70.degree. C. Monomer mixtures II (see Table 2) and initiator solution III 
are simultaneously metered to the initial charge over a period of 2 hours. 
The mixture is then stirred for 2 hours and reactivated with initiator 
solution IV. Stirring is continued for 10 hours, and the mixture is then 
neutralised with V. 
2,000 g of deionised water (VI) are then introduced into a 4-1 flask as the 
initial charge, heated to 60.degree. C. to 70.degree. C., and the contents 
of the 2-1 flask are combined therewith. The organic solvent is distilled 
off azeotropically under reduced pressure (about 200 mbar). The 
physicochemical data of the polymer solutions are listed in Table 2. 
TABLE 2 
______________________________________ 
Examples 8 9 
______________________________________ 
I. Initial charge 
Methyl isobutyl ketone: 200 g 200 g 
II. Monomer mixture: 
N,N-dimethylaminoethyl methacrylate: 
150 g 150 g 
Styrene: 135 g 165 g 
Acrylonitrile: 90 g 110 g 
Compound d2): 125 g 75 g 
III. Initiator solution: 
Azoisobutyronitrile: 12.5 g 12.5 g 
Methyl isobutyl ketone: 250 g 250 g 
IV. Reactivator solution: 
Azoisobutyronitrile: 2.5 g 2.5 g 
Methyl isobutyl ketone: 50 g 50 g 
V. Neutralising agent: 
Acetic acid: 100 g 100 g 
VI. Deionised water: 2000 g 2000 g 
Concentration: 19.8% 24.0% 
pH: 4.8 4.8 
Viscosity at 23.degree. C. (mPa .multidot. s): 
&lt;50 250 
______________________________________ 
Examples 10 and 11 
Solution I (see Table 3) is introduced into a 1-1 stirred flask equipped 
with gas inlet and outlet as the initial charge, flushed with nitrogen, 
and heated to 70.degree. C. Solution II is then metered in over a period 
of 3 hours, and the mixture is additionally stirred for 2 hours. 
The ketone solution is then metered dropwise to mixture IV and mixed 
therewith until a homogeneous mixture is obtained. Methyl isobutyl ketone 
is then distilled off (at temperatures of up to 100.degree. C.) 
azeotropically at reduced pressure. The cloudy, aqueous solution is then 
cooled and filtered. The physicochemical data are listed in Table 3. 
TABLE 3 
______________________________________ 
Examples 10 11 
______________________________________ 
I. Initial charge 
Methyl isobutyl ketone: 
100 g 100 g 
Compound d3): 37.5 g 62.5 g 
II. Monomer mixture: 
N,N-dimethylaminoethyl methacrylate: 
100 g 100 g 
Styrene: 67.5 g 52.5 g 
Acrylonitrile: 45 g 35 g 
Methyl isobutyl ketone: 
125 g 125 g 
Azoisobutyronitrile: 6.25 g 6.25 g 
III. Reactivator solution: 
Azoisobutyronitrile: 1.25 g 1.25 g 
Methyl isobutyl ketone: 
25 g 25 g 
IV. Solution of the neutralising agent: 
Acetic acid: 40 g 60 g 
Deionised water: 1000 g 1000 g 
Concentration: 20.6% 20.5% 
pH: 5.3 4.5 
______________________________________ 
Examples 12 and 13 
Solvent I (see Table 4) is introduced into a 2-1 stirred flask equipped 
with gas inlet and outlet as the initial charge, flushed with nitrogen, 
and heated to 70.degree. C. Monomer mixture II and initiator solution III 
are then evenly and simultaneously metered in over a period of 2 hours, 
and the mixture is additionally stirred for 2 hours. 
It is then reactivated with initiator solution IV. Stirring is continued 
for 10 hours, and neutralising agent V is then added. The organic polymer 
solution is then metered dropwise to water phase VI and mixed therewith 
until a homogeneous mixture is obtained. The organic solvent is then 
distilled off azeotropically at reduced pressure. The slightly cloudy, 
aqueous solution is then cooled and filtered. The physicochemical data of 
the aqueous polymer solutions are also listed in Table 4. 
TABLE 4 
______________________________________ 
Examples 12 13 
______________________________________ 
I. Initial charge 
Methyl isobutyl ketone: 200 g -- 
Toluene -- 200 g 
II. Monomer mixture: 
N,N-dimethylaminoethyl methacrylate: 
150 g 150 g 
Technical grade mixture of 
150 g 150 g 
stearyl methacrylate and 
hexadecyl methacrylate: 
Styrene: 120 g 100 g 
Acrylonitrile: 80 g 100 g 
III. Initiator solution: 
Azoisobutyronitrile: 12.5 g 12.5 g 
Methyl isobutyl ketone: 50 g -- 
Toluene: -- 50 g 
IV. Reactivator solution: 
Azoisobutyronitrile: 2.5 g 2.5 g 
Methyl isobutyl ketone: 50 g -- 
Toluene: -- 50 g 
V. Neutralising agent: 
Acetic acid: 100 g 100 g 
VI. Deionised water: 2000 g 2000 g 
Concentration: 25.9% 25.2% 
pH: 4.7 4.7 
Viscosity at RT (mPa .multidot. s): 
&lt;100 &lt;100 
______________________________________ 
Comparative Examples C1 and C2 
Solvent I (see Table 5) is introduced into a 2-1 stirred flask equipped 
with gas inlet and outlet as the initial charge, flushed with nitrogen, 
and heated to 70.degree. C. Monomer mixture II and initiator solution III 
are then evenly and simultaneously metered in over a period of 2 hours, 
and the mixture is additionally stirred for 2 hours. 
It is then reactivated with initiator solution IV. Stirring is continued 
for 10 hours, and neutralising agent V is then added. The organic polymer 
solution is then metered dropwise to water phase VI and mixed therewith 
until a homogeneous mixture is obtained. The organic solvent is then 
distilled off azeotropically at reduced pressure. The somewhat cloudy, 
aqueous solution is then cooled and filtered. The physicochemical data of 
the aqueous polymer solutions are also listed in Table 5. 
TABLE 5 
______________________________________ 
Comparative Examples 
C1 C2 
______________________________________ 
I. Initial charge 
Methyl isobutyl ketone: 
200 g 200 g 
II. Monomer mixture: 
N,N-dimethylaminoethyl 
325 g 350 g 
methacrylate: 
Styrene: 175 g 150 g 
III. Initiator solution: 
Azoisobutyronitrile: 
12.5 g 12.5 g 
Methyl isobutyl ketone: 
250 g 250 g 
IV. Reactivator solution: 
Azoisobutyronitrile: 
2.5 g 2.5 g 
Methyl isobutyl ketone: 
50 g 50 g 
V. Neutralising agent: 
Acetic acid: 186 g 201 g 
VI. Deionised water: 
2000 g 2000 g 
Concentration: 21.0% 20.2% 
pH: 4.9 4.9 
Viscosity at RT (mPa .multidot. s): 
&lt;50 &lt;50 
______________________________________ 
Production of the pigment preparations 
Auxiliaries used: 
______________________________________ 
Shellsol TD is an aliphatic hydrocarbon mixture (b.p. 
170-190.degree. C.) (Deutsche Shell Chemie 
GmbH, D-6236 Eschenbach). 
Elftex 415 carbon black pigment (Cabot GmbH, 
D-6450 Hanau). 
CHROMOSAL B 33% strength basic chromium sulphate 
(Bayer AG, LEV) 
Lipsol ES fat-liquoring agent (Schill & Seilacher, 
Boblingen). 
Coripol MB anionic fat-liquoring agent (Stockhausen, 
Krefeld) 
RETINGAN R4B-N 
resinous tanning agent (Bayer AG). 
BAYMOL A mixture of nonionic emulsifiers 
(Bayer AG). 
BLANCOROL RL chromium sulphate/syntan mixture having 
neutralising properties (Bayer AG) 
LEVOTAN K 55% strength aqueous oligourethane 
solution (Bayer AG) 
Tetrapol SAF fat-liquoring agent (Stockhausen, Krefeld) 
Agitan 295 antifoam (Munzing Chemie GmbH, 
Heilbronn) 
Preventol R 50 
benzyldodecyldimethylammonium 
chloride, 50% strength in water 
(Bayer AG) 
______________________________________ 
Example P 1 
400 g of the dispersion prepared according to Example 1 are introduced into 
a vessel as the initial charge. 100 g of dipropylene glycol, 30 g of a 
cationic product serving as disinfectant 
(benzyldodecyldimethylammoniumchloride), 200 g of Pigment Brown 25 and 15 
g of .sup..cndot. Shellsol TD and 255 g of water are added to the aqueous 
dispersion. The mixture is dispersed for 15 minutes using a dissolver at 
about 8000 rpm, and the dispersion thus prepared is transferred to a bead 
mill (ball diameter 1.5 mm). After 15 minutes, the mixture is poured off 
to give an evenly dispersed pigment preparation which when brush-coated 
onto leather does not show "comets" or other unlevelness. 
The pigment preparations listed in Table 1 were produced analogously to 
Example P 1. 
TABLE 1 
__________________________________________________________________________ 
Pigment preparations; variation of the binders 
Pigment mixture (g) 
consisting of 
PigmBrown 45: 
46 parts 
Shellsol 
Cation 
Binder PigmViolet 23: 
5 parts 
TD emuls. 
according 
Amount 
PigmYellow 13: 
46 parts 
Amount 
Amount 
Ex. 
to Ex. 
[g] .sup.R Elftex 415: 
3 parts 
[g] [g] 
__________________________________________________________________________ 
P 2 
2 400 200 10 30 
P 3 
3 310 200 10 30 
P 4 
4 370 200 10 30 
P 5 
5 430 200 10 30 
P 6 
6 480 200 10 25 
P 7 
7 600 200 10 25 
P 8 
8 465 200 10 30 
P 9 
9 383 200 10 30 
P 10 
10 450 175 20 25 
P 11 
11 450 175 20 25 
P 12 
1 450 200 20 25 
__________________________________________________________________________ 
Water-dilutable 
high-boiling 
solvent Water 
Thickener 
Antifoam 
Evaluation 
Amount 
Amount 
Amount 
Amount 
of the dyeing 
Ex. 
Type [g] [g] [g] [g] on leather 
__________________________________________________________________________ 
P 2 
Polyglycol P400 
100 250 8 2 relat. level 
P 3 
Polyglycol P400 
100 343 5 2 level 
P 4 
Polyglycol P400 
100 280 8 2 relat. level 
P 5 
Polyglycol P400 
100 220 8 2 very level 
P 6 
Polyglycol P400 
100 185 -- -- relat. level 
P 7 
Polyglycol P400 
100 65 -- -- very level 
P 8 
Dipropylene glycol 
100 193 -- 2 level 
P 9 
Dipropylene glycol 
100 275 -- 2 relat. level 
P 10 
Polyglycol P400 
100 222 5 3 level 
P 11 
Polyglycol P400 
100 224 3 3 level 
P 12 
Polyglycol P400 
100 224 3 3 see Ex. A4 
__________________________________________________________________________ 
Examples P 13 to P 17 
The pigment preparations listed in Table 2 were produced analogously to 
Examples P 1 to P 12 under comparable conditions. The good to excellent 
levelness and colour depth of the preparations based on the pigment 
binders according to the invention upon application to leather can be seen 
from this table. In contrast thereto, the pigment preparations based on 
Comparative Examples 1 and 2 are clearly less suitable. 
TABLE 2 
__________________________________________________________________________ 
Pigment preparations; comparison with preparations not according to the 
invention 
Cation. 
Polyglycol Antifoam 
Evaluation 
Binder Pigment 
Shellsol 
emulsifier 
P 400 Water 
.RTM. Agitan 
of the 
according .RTM. Elftex; 
TD Amount 
Amount 
Amount 
Amount dyeing on 
Ex. 
to Ex. 
Amount 
Amount (g) 
Amount (g) 
(g) (g) (g) (g) leather 
__________________________________________________________________________ 
P13 
8 248 125 5 15 50 110 1-2 level 
P14 
12 193 125 5 15 50 115 1-2 very level 
P15 
13 197 125 5 15 50 110 1-2 very level 
P16 
C 1 238 125 5 15 50 70 1-2 unlevel 
P17 
C 2 248 125 5 15 50 60 1-2 unlevel 
__________________________________________________________________________ 
USE EXAMPLES 
Example A 1: Dyeings of a Wet Blue 
A wet blue suitable for furniture nappa (containing 2.8% of Cr2O.sub.3), 
shaved thickness 1.1 mm is washed at 40.degree. C. with 300% of water (pH 
4.5). 200% of water at 40.degree. C. is then added again, the pH is 
brought to 4 with formic acid (diluted 1:10), and, after 20 minutes, 2% of 
the pigment preparation P 1 (diluted 1:5) are added. After 60 minutes, 2% 
of a 33% strength basic chromium sulphate (.sup..cndot. CHROMOSAL B from 
Bayer AG) are added; this is followed by a 30-minute run, after which 
neutralisation and retanning by the customary procedure are started. In a 
modified procedure, a uniformly dyed wet blue was crossdyed during 
retanning with 3% of Acid Orange 51 by known methods. 
Not only the leather dyed exclusively with pigment but also the leather 
crossdyed with a dyestuff were very well penetrated, natural leather 
defects were accidentally hidden, and the entire colour was very uniform. 
Example A 2 
Example A 1 was repeated, using 1% of pigment. After only 30 minutes, the 
addition of chrome tanning agent took place. 
Although the leather colour in this case was uniform but somewhat less 
strong, the leather cross-section was not very well penetrated. 
Example A 3: Dyeing of a Crust Leather 
A commercially retanned crust leather of shaved thickness 1.4 mm is wetted 
back in 1000% of water at 40.degree. C. with 2% of ammonia (diluted 1:10) 
and after 10 minutes with 2% of an emulsifying fat-liquoring agent 
(.sup..cndot. Lipsol ES) for 120 minutes. The liquor is discharged, the 
leather is rinsed, and 600% of water at 40.degree. C. is added. 2% of an 
anionic fat-liquoring agent (.sup..cndot. CORIPOL MB) and, after a further 
30 to 60 minutes, 1 to 2% of formic acid (diluted 1:10) are added. At this 
point, the liquor should have a pH of 4. Then 1% of a resinous tanning 
agent (.sup..cndot. Retingan R4 B-N) is added, and, after a running time 
of 10 minutes, 2.5% of a pigment (diluted 1:5 with water) according to 
Example P10 are added. (After a running time of about 40 minutes, the 
liquor can be acidified to a pH of 3.8 to 4 with 0.5% of formic acid 
(diluted 1:10); however, this acidification is in general omitted.) The 
leather is then dried and finished in the customary manner. 
The leathers obtained have been uniformly dyed; they have excellent 
water-drop fastness, light fastness and migration stability. 
Example A 4: Dyeing of a Velour Leather 
5 wet blue splits (thickness 1.7 mm) were washed in a drum with 300% of 
water (50.degree. C.) and 0.5% of BAYMOL A for 30 minutes, and the liquor 
was discharged. 
50% of water (50.degree. C.) and 0.5% of formic acid (which previously had 
been diluted with water in a weight ratio of 1:10 ) was added, and after a 
running time of 5 minutes, 4% of pigment P12 (Experiment A) was added. 
After 90 minutes, 2% of CHROMOSAL B, after 15 minutes 2% of BLANCOROL RC, 
after 30 minutes 4% of LEVOTAN K and after another 60 minutes 1% of sodium 
formate were added. The pH of the liquor is 4.1. 
The leather is then washed with water at 40.degree. C. for 10 minutes. 100% 
of water (40.degree. C.) containing 2.2% of sodium bicarbonate are brought 
in (pH=6.4), after 40 minutes 7% of CORIPOL MB are added together with 
0.5% of TETRAPOL SAF, followed by a running time of 60 minutes (pH=6.0). 
The liquor is discharged. 
In Experiment B, 4% of pigment as above and, after 60 minutes, 2% of 
CORIPOL MB are added. After 30 minutes, the leather is rinsed with warm 
water at 20.degree. C. for 5 minutes. 
The leathers are placed on the horse, predried at 70.degree. C. in vacuo (3 
minutes) and finally completely dried on a suspender. After 
air-conditioning, they are staked, buffed and freed from dust. 
Leather A was dark-brown; leather B was black. 
The leathers were tested for light fastness (DIN [German Standards 
Specification]53,343=IUF 402). They were exposable to light to above 4 on 
the blue scale (Acid Blue 121) without impairment. The perspiration 
fastness (IUF 426) and the migration stability (IUF 442) were excellent. 
In a further experiment (C), leather A was crossdyed after fat-liquoring, 
with 3% of Acid Black 210 and finished in a customary manner.