Water-soluble cationic oligourethane resins and the use thereof for the treatment of pelts or leather

This invention relates to water-soluble, cationic hydrophilic oligourethanes free from isocyanate groups and containing methylol groups and to the use thereof for the tanning, pre-tanning or re-tanning of pelts or pre-tanned leather and as dyeing auxiliaries.

BACKGROUND OF THE INVENTION 
In German Offenlegungsschrift No. 2,504,081 (British Pat. No. 1,495,598), 
there has been described a process for the tanning or re-tanning of pelts 
or leather, which is characterized in that pelts or leather are treated 
with an aqueous liquor containing: 
(a) hydrophilic oligourethanes which may be methylolated and which have a 
molecular weight (Mn) of from 300 to 20,000; and, optionally, 
(b) formaldehyde or a substance from which formaldehyde is split off. 
The oligourethanes described there are generally based on water-soluble 
polyethers having a molecular weight below 500 and they are preferably 
free from ionic groups. However, German Offenlegungsschrift No. 2,504,081 
(British Pat. No. 1,495,598) also mentions oligourethanes which contain 
sulphonate groups and are based on hydrophobic, water-insoluble 
polyethers. It is expressly pointed out in this connection that the 
incorporation of ionic groups into the oligourethane resin should be 
considered in cases where hydrophobic polyhydroxyl compounds or 
combinations of hydrophobic with non-ionic, hydrophilic polyhydroxyl 
compounds are used for the synthesis of the oligourethane. As is well 
known to those skilled in the art, the incorporation of ionic centers 
enables even those oligourethanes to be dissolved in water which, in the 
absence of the ionic center, are neither soluble in water nor dispersable 
therein. 
In the course of further development of the known process, it has now 
surprisingly been found that aqueous solutions of such oligourethane 
resins are greatly improved in the tanning and dyeing characteristics 
thereof, if, in addition to hydrophilic polyethylene glycol polyethers, 
they contain cationic centers obtained in known manner by the reaction of 
a tertiary nitrogen atom with a quaternizing agent and/or an acid. 
It is found particularly advantageous to use the quaternizing agent and/or 
the acid in sub-equivalent quantities, based on the tertiary nitrogen, so 
that the pH of the resulting aqueous solution of the cationic 
oligourethane is between about 5 and 10, preferably between about 7 and 9. 
The aqueous oligourethane solutions according to the present invention have 
the following advantages over solutions known in the art: 
1. They have excellent resistance to electrolytes in spite of the cationic 
character thereof. 
2. The anionic character of re-tanned chrome leather is over-compensated. 
3. The products have a soft tanning effect. 
4. The products may be used for pre-tanning without deleteriously affecting 
the subsequent chrome tanning. 
5. The cationic oligourethane solutions improve the consumption of the 
anionic dyes and produce a more brilliant and more intense color without 
deleteriously affecting the levelling of the dyeing. 
SUMMARY OF THE INVENTION 
The present invention thus relates to water-soluble oligourethanes which 
contain methylol groups and are free from isocyanate groups and have a 
molecular weight (Mn) of between about 600 and 5,000 based on: 
(a) polyethylene glycol ethers having a molecular weight (Mn) between about 
400 and 1,500; 
(b) polyisocyanates; and, optionally, 
(c) compounds which are mono- or poly-functional towards isocyanates, 
preferably alcohols, having a molecular weight below about 300; and 
(d) formaldehyde, 
characterized in that the proportion of component (a) in the oligourethane 
is from about 40 to 90%, by weight, preferably from about 60 to 80%, by 
weight, and in that component (a) and/or (c) together contain a total of 
from about 20 to 200 milliequivalents, preferably from about 30 to 100 
milliequivalents, of tertiary nitrogen atoms per 100 g of oligourethane 
solids content, from about 20 to 95% of which tertiary nitrogen atoms, 
preferably from about 60 to 90% thereof, have been converted into 
quaternary ammonium nitrogen or into the ammonium salt form by treatment 
with alkylating agents and/or acids. 
The present invention also relates to a process for tanning or re-tanning 
pelts or leather, characterized in that the pelts or leather are treated 
with an aqueous solution of the oligourethanes according to the present 
invention, which solution is at a pH of between about 5 and 10, preferably 
between about 7 and 9, and most preferably between about 7 and 8. 
DETAILED DESCRIPTION OF THE INVENTION 
The polyethylene glycol ethers used in the preparation of the oligourethane 
resins according to the present invention may be polyethers having an 
average functionality of from about 1.8 to 4, preferably from about 2 to 
3, and a molecular weight (Mn) of from about 400 to 1,500. These 
polyethers may be obtained in known manner by the addition of ethylene 
oxide to starting components which contain reactive hydrogen atoms, such 
as alcohols, amines or water. Other epoxides may also be used in minor 
quantities, e.g. propylene oxide or butylene oxide, but the proportion 
thereof should always be below about 20%, preferably below about 10%. Pure 
polyethylene glycol polyethers which have an average molecular weight (Mn) 
between about 500 and 1,200 and form a clear solution in water are 
particularly preferred. 
Polyethylene glycol polyethers which have been started on compounds, such 
as ammonia, primary amines or amino alcohols, and therefore contain 
tertiary amino groups are also particularly preferred. When such 
polyethers are used, the use of a low molecular weight tertiary amines as 
reactants may be dispensed with. 
The polyisocyanates used may, in principle, be any aliphatic, 
cycloaliphatic, araliphatic, aromatic or heterocyclic polyisocyanates, 
such as those mentioned, for example, in German Offenlegungsschrift No. 
2,504,081 (British Pat. No. 1,495,598). Aliphatic and cycloaliphatic 
polyisocyanates are preferred on account of the fastness to light thereof, 
in particular 1,6-diisocyanatohexane, 1,4-diisocyanatobutane and 
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane. 
1,6-diisocyanatohexane is particularly preferred. For the manufacture of 
leathers in dark colors or yellowish brown shades, products based on 
aromatic isocyanates may also be used. Particularly preferred aromatic 
polyisocyanates in such cases are 2,4-diisocyanatotoluene, 
2,6-diisocyanatotoluene and isomeric mixtures thereof, 
2,4'-diisocyanatodiphenyl methane and 4,4'-diisocyanatodiphenylmethane and 
isomeric mixtures thereof. 
The mono- or poly-functional isocyanate reactive low molecular weight 
compounds which may be used in the synthesis of the oligourethanes 
according to the present invention in quantities of less than about 30% by 
weight, preferably less than about 15%, by weight, based on the 
oligourethane, include not only the known monohydric and polyhydric 
alcohols, such as ethylene glycol, diethylene glycol, 1,2- and 
1,3-propylene glycol, dipropylene glycol, 1,4- and 2,3-butane diol, 
glycerol, trimethylol propane and 1,2,4-hexane triol, but especially also 
compounds which contain tertiary nitrogen atoms. Particularly suitable 
compounds of this type are basic monohydric and dihydric alcohols such as 
dimethylamino ethanol, dimethylamino propanol, diethylamino ethanol, 
diethylamino propanol, N-hydroxyethyl-pyrrolidine, 
N-hydroxyethyl-piperidine, N-methyldiethanolamine, N-ethyl-diethanolamine 
and N-methyl-diisopropanolamine. Other suitable amino alcohols have been 
mentioned, for example, in German Offenlegungsschrift No. 1,770,068 (page 
18) which corresponds to U.S. Pat. No. 3,756,992. 
As isocyanate-reactive compounds there may also be used di-tertiary 
diamines in combination with a quaternizing agent which contains at least 
one Zerewitinoff active hydrogen atom in addition to the quaternizing 
group, for example bromoethanol, so that the polyisocyanate addition 
reaction is accompanied by a quaternizing polyaddition reaction in situ. A 
process of this type for the preparation of ionic isocyanate polyaddition 
products has been described, for example, in German Auslegeschrift No. 
1,495,770 which corresponds to U.S. Pat. No. 3,535,274. 
The following are examples of suitable di-tertiary diamines (which may, of 
course, also be fixed in the oligourethane molecule by subsequent reaction 
with quaternizing groups of the oligourethane): N,N'-tetramethyl-ethylene 
diamine, N,N'-tetramethyl-hexamethylene diamine, pentamethyl-diethylene 
triamine, pentamethyl-dipropylene triamine, N,N'-dimethylpiperazine, 
N,N'-bis-(3-dimethyl-aminopropyl)-urea and 
N,N'-bis-(3-dimethyl-aminopropyl)-oxamide. 
Inclusion of the above-mentioned tertiary amino alcohols or of di-tertiary 
diamines in the synthesis of the oligourethanes according to the present 
invention is not absolutely necessary, except when the polyethylene glycol 
polyether used is free from tertiary amino groups. Nitrogen atoms capable 
of being quaternized may, of course, be introduced both by the 
polyethylene glycol polyether and by, for example, tertiary amino 
alcohols. 
The total quantity of tertiary and quaternary nitrogen and nitrogen in the 
ammonium salt form present in the oligourethane resin should be at least 
about 0.3%, by weight, and is preferably from about 0.35 to 1.8%, by 
weight. 
C.sub.1 to C.sub.20 monohydric alcohols are advantageously used as 
chain-breaking agents in the preparation of the oligourethanes according 
to the present invention. If a basic monohydric alcohol, such as 
dimethylamino ethanol, for example, is in any case used for introducing 
tertiary nitrogen atoms, this compound may take over the function of a 
chain-breaking agent, in which case no other monohydric alcohols need be 
used. The following are examples of non-basic C.sub.1 -C.sub.20 monohydric 
alcohols: methanol, ethanol, propanol, isopropanol, 1-butanol, glycol 
monomethyl ether, glycol monoethyl ether, glycidol, 
3-hydroxy-methyl-3-ethyl-oxetane, 2-chloroethanol, 2-bromo-ethanol, 
trichloroethanol, diethylene glycol monomethyl ether, 2-butanol, 
2methyl-1-propanol, pentanol, 3-methyl-1-butanol, 2,2-dimethyl propanol, 
hexanol, 2-ethyl-1-butanol, octanol, 2-ethyl hexanol, decanol, dodecanol, 
tetradecanol, hexadecanol, octadecanol, fatty alcohol mixtures of the type 
obtainable commercially as "Lorol" or "Alfol", 2-isopropoxy ethanol, 
2-butoxy ethanol, 2-(2-butoxy ethoxy)-ethanol, 2-ethyl-thioethanol, 
cyclohexanol, methylcyclohexanol, hydroxymethyl-cyclohexane, 
trimethyl-cyclohexanol and 4-tertiary butylcyclohexanol. C.sub.1 to 
C.sub.6 monohydric alcohols are preferred, particularly methanol and 
ethanol. 
The quaternizing agents used may, in principle, be any mono-functional or 
di-functional alkylating agents, such as those mentioned, for example, at 
page 20 of German Offenlegungsschrift No. 1,770,068 and at pages 2 and 3 
of German Offenlegungsschrift No. 1,300,275 (British Pat. No. 1,055,511). 
The following are particularly preferred: dimethyl sulphate, diethyl 
sulphate, epichloro-hydrin, chloroacetamide, chloroacetic acid methyl 
ester, chloroacetic acid ethyl ester, p-toluene-sulphonic acid methyl 
ester, bromoethanol, ethylene glycol, monobenzene sulphonate, 
dichlorobutene and dibromobutane. Quaternizing agents which are free from 
chlorine and bromine atoms are preferred above all others. The quantity of 
alkylating agent used should be at the most about 95%, preferably from 
about 60 to 90% of the quantity required for complete quaternization. 
Particularly simple and therefore preferred according to the present 
invention is the formation of a salt of the tertiary amino groups in the 
oligourethane with inorganic or organic acids. Suitable acids for this 
purpose have been mentioned in German Pat. Nos. 1,178,586 (British Pat. 
No. 1,043,260) and 1,179,363 (U.S. Pat. No. 3,480,592). Sulphuric acid, 
phosphorous acid and phosphoric acid are preferred inorganic acids. They 
should be used in such quantities that the pH of the aqueous solution of 
the cationic oligourethane is not below about 5 preferably not below about 
7. 
This is the case when the molar quantity of these acids is not more than 
about 50% of the molar quantity of tertiary nitrogen atoms present. 
Among the preferred organic acids are to be included the sulphonic acids of 
aromatic compounds, e.g. the commercially readily available naphthalene, 
ditolyl ether and terphenyl sulphonic acids and the condensation products 
thereof with formaldehyde and dihydroxy diphenyl sulphone. Other acids 
known as synthetic tanning agents may also be used in this connection. 
Another group of preferred acids are the organic carboxylic acids having 
from 1 to 6 carbon atoms, e.g. acetic acid, lactic acid, glycolic acid, 
oxalic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, 
citric acid or commercial mixtures thereof. When these acids are used, the 
pH of the aqueous oligourethane solutions again should not be below about 
5, preferably not below about 7. Owing to the powerful buffering action of 
products obtained with these acids, the quantity of these acids may vary 
within a wide range and may, for example, lie above the point of 
equivalence. The cationic oligourethane solutions in all cases still 
contain some free tertiary amino groups, either due to incomplete 
quaternization or due to incomplete salt formation or due to partial 
hydrolysis of the salts obtained by reaction with the acids. 
According to another preferred embodiment of the present invention, 
alcohols containing carboxylic acid or sulphonic acid groups or salts 
thereof are used for the synthesis of the oligourethanes in addition to 
the starting compounds mentioned above. However, the molar quantity of 
anionic groups introduced in this way should be smaller than that of the 
tertiary nitrogen atoms before quaternization. 
The following are examples of such compounds: hydroxymethane and 
hydroxyethane sulphonic acid and salts thereof; adducts of sulphurous acid 
and unsaturated alcohols, such as allyl alcohol, methallyl alcohol, 
butene-(2)-diol (1,4), butene(1)-diol (3,4), maleic acid-bis-glycol esters 
and alkoxydation products of these alcohols; glycolic acid, lactic acid, 
dimethylpropionic acid and dimethyl butyric acid and salts thereof. 
Synthesis of the oligourethanes may be carried out, for example, by first 
reacting the polyethylene glycol ether with the polyisocyanate and then 
reacting the resulting prepolymer with the low molecular weight 
isocyanate-reactive compounds, if used. It is preferred, however, to react 
all the starting components together (optionally also including the 
quaternizing agent at this stage) in a one-shot process. An inert solvent 
may be used if desired, but the process is preferably carried out solvent 
free. 
When preparing oligourethanes exclusively from difunctional or higher 
functional components, an NCO/OH ratio of from about 0.4 to 0.8, 
preferably from about 0.5 to 0.7, is observed in order to obtain the 
desired low molecular weight. If mono-functional chain-terminating agents 
are used, the NCO/OH ratio observed is from about 0.5 to 1.0, preferably 
from about 0.6 to 0.9 Oligourethanes which contain at least a proportion 
of OH end groups are preferred. 
The oligourethanes obtained in this way, which are free from isocyanate 
groups, are methylolated in the presence of water with formaldehyde, 
paraformaldehyde or other compounds which split of formaldehyde. The molar 
quantity of formaldehyde used amounts to about 20 to 120%, preferably from 
about 30 to 70%, of the molar quantity of urethane groups present. A 
larger excess of formaldehyde could, of course, be employed, but has no 
advantages. A suitable method of carrying out this methylolation consists 
of stirring an aqueous formaldehyde solution, at room temperature or at 
temperatures of from about 30.degree. to 80.degree. C., into the basic 
oligourethane, which may be quaternized or neutralized, and then diluting 
the product with water. Alternatively, methylolation may be carried out by 
adding formaldehyde as the last step of the reaction to the previously 
prepared aqueous solution of the oligourethane. Methylolation is assisted 
and the quantity of free formaldehyde reduced by stirring the aqueous 
solution of the reactants for several hours at from about 30.degree. to 
90.degree. C. 
According to the present invention, the oligourethanes are generally used 
as tanning liquors in the form of from about 0.1 to 50%, preferably from 
about 1 to 20%, aqueous solutions. 
The treatment of the leather or pelts with the tanning liquors according to 
the present invention may be carried out in any known apparatus, such as 
tanning vats, tanning mixers, the tanning apparatus manufactured by 
Hagspiel (Federal Republic of Germany) or in machines, such as Staromat 
.RTM. and Coretan .RTM.. The process according to the present invention is 
generally carried out at temperatures of from about 10.degree. to 
90.degree. C., preferably from about 30.degree. to 60.degree. C. 
Dyes are absorbed very uniformly on leather which has been treated with the 
products according to the present invention. The consumption of anionic 
dyes from the liquor is excellent. Brilliant and intense dyeings are 
obtained. 
Leathers which have been tanned according to the present invention may be 
dressed or finished by any known method. They are flexible, pleasant to 
the skin, porous, soft and white, and if aliphatic oligourethanes are used 
they are also light-fast. Owing to the white background, highly brilliant 
colors may be obtained on the leather. 
In the sum total of the properties thereof, leathers which have been tanned 
with the cationic oligourethanes according to the present invention and 
dyed are superior to those which have been manufactured from comparable 
oligourethanes containing no cationic groups and without the particular 
highly hydrophilic polyethers.

The following Examples serve to illustrate the present invention. (Figures 
given for the parts denote parts, by weight, or percentages, by weight, 
unless otherwise indicated). 
EXAMPLES 
Examples 1 to 7 
The following mixture of hydroxy-functional compounds is introduced into a 
reaction vessel at room temperature: 492 g (0.8 mol) of a polyoxyethylene 
glycol having a molecular weight (Mn) of 615, 23.8 g (0.2 mol) of 
N-methyl-diethanolamine and 19.2 g (0.6 mol) of methanol. 
The quantity of 1,6-diisocyanatohexane indicated in the Table is added and 
the mixture is heated, if necessary, to 80.degree. C. until no more free 
isocyanate groups may be detected. A solution of 3.3 g of crude commercial 
glutaric acid in 200 g of water and 65 g of a 37% aqueous formaldehyde 
solution (0.8 mol) are then added and the mixture is finally diluted with 
water to a solids content (including formaldehyde) of 55%. 
______________________________________ 
Example 1 2 3 4 5 6 7 
______________________________________ 
1,6-diiso- 
cyanato- 
hexane (g) 
117.6 134.4 151.2 
168.0 184.8 201.6 215.0 
(mol) 0.7 0.8 0.9 1.0 1.1 1.2 1.28 
ph 7.6 7.8 7.3 7.3 7.3 7.5 7.6 
______________________________________ 
Example 8 
The procedure is the same as in Example 2, but 53.4 g (0.6 mol) of 
dimethylaminoethanol are used instead of methanol. 
46.2 g of crude commercial glutaric acid are used as a neutralizing 
component. The clear, aqueous solution obtained as a thin liquid has a pH 
of 7.5. 
Example 9 
The following components are reacted analogously to Example 1: 
615 g (1 mol) of a polyoxyethylene glycol, m. wt. (Mn) 615, 
53.4 g (0.6 mol) of dimethylaminoethanol, 
134.4 g (0.8 mol) of 1,6-diisocyanatohexane, 
36.2 g of crude commercial glutaric acid and 
65 g of a 37% aqueous formaldehyde solution. 
The solvent free liquid is diluted with water to a solids content of 54% 
(pH=7.0). 
Example 10 
The following components are reacted analogously to Example 1: 
492 g (0.8 mol) of a polyoxyethylene glycol, m. wt. (Mn) 615, 
23.8 g (0.2 mol) of N-methyl-diethanolamine, 
30 g (0.3 mol) of cyclohexanol, 
9.6 g (0.3 mol) of methanol, 
134.4 g (0.8 mol) of 1,6-diisocyanatohexane, 
3.3 g of commercial glutaric acid and 
65 g of a 37% aqueous formaldehyde solution. 
The solvent free liquid is diluted with water to a solids content of 54% 
(pH=7.3). 
Example 11 
The procedure is the same as in Example 9, but instead of glutaric acid, 
carbonic acid is used for neutralization by adding 50 g of solid carbon 
dioxide (carbon dioxide snow) to the previously prepared aqueous solution. 
A steam of gaseous carbon dioxide is then passed through the solution for 
2 hours.(pH=7.7). 
Example 12 
Example 2 is repeated and an 80% aqueous solution of the product is 
prepared (pH=7.6). 
Example 13 
The following components are reacted analogously to Example 1: 
349 g (0.6 mol) of a polyethylene oxide (OH number 289) which has been 
started on triethanolamine, 
19.2 g (0.6 mol) of methanol, 
134.4 g (0.8 mol) of 1,6-diisocyanatohexane 
11,6 g of glutaric acid (technical grade) and 65 g of 37% aqueous 
formaldehyde solution. 
The solvent free liquid is diluted with water to a solids content of 54% 
(pH=7.4). 
Examples 14 to 18 
Example 2 is repeated using different quantities of formaldehyde: 
______________________________________ 
EXAMPLE 2 14 15 16 17 18 
______________________________________ 
Formaldehyde 0.8 0.7 0.6 0.5 0.4 0.3 
(mol) 
(g) 24 21 18 15 12 9 
% formalde- 
hyde 3.5 3.0 2.6 2.2 1.75 1.3 
pH 7.5 7.5 7.5 7.4 -- -- 
______________________________________ 
Example 19 
The procedure is the same as in Example 15 and the solvent free liquid is 
diluted with water to a solids content of 80% (pH=8). 
Example 20 
The procedure is the same as in Example 2, but instead of 19.2 g of 
methanol, a mixture of 54 g (0.2 mol) of stearyl alcohol and 12.8 g (0.4 
mol) of methanol is used as chain-breaking agent. When the solvent-free 
liquid is diluted to a solids content of 54%, a highly viscous paste is 
obtained which may be diluted with water to form a hydrosol (pH=7.3). 
Example 21 
The procedure is the same as in Example 2, but instead of 3.3 g of glutaric 
acid, 2.2 g of an 85% orthophosphoric acid are used for neutralization 
(pH=7.5). 
Example 22 
Example 2 is repeated, using 12.5 g of 40% metaphosphoric acid (pH=7.5). 
Example 23 
Example 2 is repeated, using 34 g of 5% sulphuric acid (pH=7.5). 
Example 24 
Example 2 is repeated, but without glutaric acid. When the solvent-free 
liquid is free from isocyanate groups, 90% of the tertiary amino groups 
are quaternized using 16.8 g of chloroacetamide (0.18 mol) at 80.degree. 
C. for 3 hours. Formaldehyde is then added and the liquid is diluted with 
water in the conventional manner (pH=8.3). 
Example 25 
The following mixture of hydroxy functional compounds is introduced into 
the reaction vessel at from 40.degree. to 50.degree. C.: 
492 g (0.8 mol) of a polyoxyethylene glycol, m. wt. (Mn) 615, 
41 g (0.1 mol) of the adduct of 3.8 mol of propylene oxide and 1 mol of 
1.4-dihydroxy butane-2-sulphonic acid sodium, 
11.9 g (0.1 mol) of N-methyl-diethanolamine and 
19.2 g (0.6 mol) of methanol. 
134.4 g (0.8 mol) of 1,6-diisocyanatohexane are added and the mixture is 
left to react for about 30 minutes at from 80.degree. to 82.degree. C. 
until the solvent-free liquid is free from isocyanate groups (IR 
spectrum). 10 g (0.08 mol) of dimethyl sulphate are then added dropwise to 
quaternize 80% of the tertiary amino groups. After a further 30 minutes 
stirring at 80.degree. C., 605 g of water containing 24 g of formaldehyde 
are stirred in. A 54% aqueous solution of the oligourethane (pH=7.1) is 
obtained. 
Example 26 
The procedure is analogous to that of Example 24, but 22.7 g of dimethyl 
sulphate are used as quaternizing agent instead of chloroacetamide 
(pH=6.9). 
Comparison Experiment 1 
The procedure is the same as in Example 2, but without subsequent partial 
neutralization of the tertiary amino groups. The 54% aqueous solution has 
a pH of 9. 
Comparison Experiment 2 
The procedure is the same as in Example 2, but with the addition of 36 g 
(0.6 mol) of urea instead of methanol. (pH=7.4). 
Example 27 
In a tanning flask, approximately 200 g of preserved calf pelt in 200 g of 
water are tanned for 24 hours at room temperature using 10% (based on the 
dry substance) of a product prepared according to Example 21. The leather 
obtained from this process has a shrinkage temperature of 85.degree. C. 
(as compared with 63.degree. C. of the untreated pelt). 
The tanned leather dried to a white color. 
The products from the following Examples were tested analogously and the 
following shrinkage temperatures were found: 
______________________________________ 
Shrinkage 
% of dry substance based 
temperature 
Example on the weight of pelt 
(.degree. C.) 
______________________________________ 
22 10 86 
23 10 88 
24 10 87 
25 10 88 
26 10 87 
1 10 86 
2 10 87 
3 10 86 
4 10 85 
5 10 84 
6 10 85 
7 10 85 
8 10 84 
9 10 84 
10 10 87 
11 10 84 
12 10 87 
13 10 89 
14 10 85 
20 90 
15 10 85 
20 89 
16 10 84 
20 89 
17 10 82 
20 88 
18 10 80 
20 87 
19 10 86 
20 10 85 
Comparison Experi- 
ment 2 10 75 
______________________________________ 
Example 28 
(A) 1% of a product according to Example 15 and 1% of a 90% greasing agent 
based on chloroparaffin were added to half a cow hide which had been 
de-limed by the conventional process and the hide was left in the vat with 
30% liquor for 1 hour. It was then pickled and chrome tanned in the same 
bath in the conventional manner. 
(B) The other half of the hide was treated analogously, but without the 
product according to the present invention. 
The half treated in Experiment (A) was softer and had a firmer grain than 
the half treated in Experiment (B). 
While Experiment (A) was being carried out, the sample was tested for the 
presence of dichlorodimethyl ether (DCMA) after the addition of the 
pickling substances. No DCMA could be detected gas chromatographically or 
by mass spectroscopy. Limit of detection of the method: 100 ppb. 
Example 29 
A sample was pre-tanned and finished analogously to Example 28 for 
comparison with glutaric dialdehyde. 
Results: 
With product according to the present invention: 
Surface Yield:+4% 
Tear resistance 207 (with glutaric dialdehyde 170) kg/cm.sup.2. 
Tear propagation resistance 37 (as against 30) kg/cm. 
Resistance to tearing by stitching 69 (as against 59) kg/cm. 
Example 30 
(A): A pared chromed neat's leather was neutralized in the vat in the 
conventional manner and washed. 3% of a product according to Example 2 
were added at 40.degree. C. and the leather was left to stand in the vat 
for 30 minutes. It was then dyed in the same bath using 1% of an acid 
substantive leather dye and greased and acidified in the conventional 
manner. 
(B): The other leather half used for comparison was treated with analogous 
quantities of a commercial tanning auxiliary based on a protein 
hydrolysate. 
The leather obtained in Experiment (A) had a deeper color than that 
obtained in Experiment (B). The following .crclbar. values were found in 
the dyeometer: 
(A): 100 
(B): 88 
Example 30 (A) was repeated with the products from Examples 1 to 7, 9 and 
24. The following .crclbar. values were obtained. 
______________________________________ 
Example .crclbar. 
______________________________________ 
1 88 
3 90 
4 88 
5 81 
6 82 
7 83 
9 89 
24 102 
______________________________________ 
Extraction of the dye bath by the product manufactured in the Comparison 
Experiment 1 is comparable to that by the leather treated according to 
Example 30 (A), but the levelling of the dyeing is distinctly inferior. 
Example 31 
(A): 6% of a product according to Example 9 are added to a pared chromed 
neat's leather and in the same bath the leather is neutralized to pH 4.5 
and dyed, greased and re-tanned in the conventional manner. 
(B): Comparable halves were treated analogously with a retanning substance 
containing chromium. 
There was no difference between (A) and (B) in the depth of color, 
brilliance and levelling. This is an advantage in view of the 
environmental pollution caused by effluent which contains chromium. 
It is to be understood that any of the components and conditions mentioned 
as suitable herein can be substituted for its counterpart in the foregoing 
examples and that although the invention has been described in 
considerable detail in the foregoing, such detail is solely for the 
purpose of illustration. Variations can be made in the invention by those 
skilled in the art without departing from the spirit and scope of the 
invention except as is set forth in the claims.