Leather fatliquoring agents combinable with tanning and retanning compositions

A leather fatliquoring agent and a process for its use in which the agent is a sulfosuccinic (C.sub.12-24 fatty residue) ester and an anionic or nonionic emulsifier. The agent is stable in the presence of tanning liquor electrolytes.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to fatliquoring agents which may be used 
simultaneously with electrolyte tanning liquors in leather manufacture. 
2. Statment of the Related Art 
Generally, the process steps in the manufacture of leather from hides which 
have already been fleshed, unhaired, bated, and pickled, comprise 
sequentially: tanning (to convert the hide into a stable, non-putrescible 
material, usually using chromium or aluminum salts); wringing (to remove 
excess moisture); splitting and shaving/skiving (to adjust the thickness); 
retanning (to impart desirable properties of other tanning agents); 
coloring or tinting (where desired); fatliquoring (to lubricate the fibers 
for flexibility); followed by various non-chemical steps such as 
conditioning, staking, buffing, finishing, and plating. The existence of 
so many steps results in a labor-intensive and/or machinery-intensive 
manufacturing process with resultant high costs. Therefore, anything which 
will combine steps or reduce or eliminate a step is of great economic 
importance, in addition to any improved properties of the leather that may 
result. Furthermore, it would be useful if a fat-liquoring composition 
could be at least partially combined with the tanning and/or retanning 
compositions. This would increase leather suppleness and grain stability, 
and also would make the fatliquor composition more versatile, since it 
would not be necessary to remove the tanning liquor when fatliquoring. 
Published German patent application No. 16 69 347 describes a process for 
the fatliquoring of leather using water-emulsifiable sulfosuccinic acid 
esters which have been obtained by the esterification of fat- or oil-like 
compounds containing alcoholic hydroxyl groups and also lipophilic 
residues with maleic acid anhydride followed by reaction of the 
esterification product with a sulfite or bisulfite in a quantity 
substantially equimolar to the maleic acid anhydride used. However, the 
use of compounds such as these is confined to fatliquoring. They cannot be 
used during chrome or aluminum tanning or retanning on account of the 
inadequate emulsion stability of the sulfosuccinic acid esters with 
respect to chromium or aluminum salts, and therefore cannot afford the 
advantages of the present invention.

DESCRIPTION OF THE INVENTION 
It has now surprisingly been found that sulfosuccinic acid esters may be 
used as fatliquoring agents in the tanning liquor in the manufacture of 
leather and skins, even during chrome tanning or aluminum tanning or 
retanning, providing they are combined with certain anionic or nonionic 
emulsifiers. 
Other than in the operating examples, or where otherwise indicated, all 
numbers expressing quantities of ingredients, reaction conditions, or 
defining ingredient parameters used herein are to be understood as 
modified in all instances by the term "about". 
Accordingly, the present invention relates to a process for making leather 
and skins by chrome or aluminum tanning or retanning, characterized by the 
use of a combination of 
(A) from 40 to 90 (preferably 50 to 85)% by weight of sulfosuccinic acid 
esters containing C.sub.12-24 fatty residues as esterification component, 
and 
(B) the balance to 100% by weight of nonionic and/or anionic emulsifiers 
selected from the group comprising (a) alkylene oxide adducts with 
C.sub.8-20 fatty alcohols, alkyl phenols, fatty acids or fatty acid 
alkanolamides or (b) sulfuric acid esters thereof in the form of their 
alkali, ammonium or amine salts. 
The combination is used in a total quantity of 0.1 to 6.0 (preferably 0.5 
to 4.0)% by weight based on the weight of the dehaired or shaved skins, as 
a fat-liquoring agent which may be mixed with the tanning liquor, the 
amount used depending upon the type of leather being manufactured. The 
components may be added to the liquor either separately or in the form of 
a made-up product. 
The sulfosuccinic acid esters (A) are produced in known manner by 
esterifying maleic acid anhydride with 1 to 2 equivalents of the desired 
esterification component and reacting the esterification product with a 
sulfite or bisulfite in a quantity substantially equivalent to the maleic 
acid anhydride. Compounds containing C.sub.12-24 fatty residues and 
hydroxyl groups may be used as the esterification component. 
The fatty residues may be saturated or unsaturated, linear or branched. 
They may be derived from: fatty alcohols; branched-chain alcohols produced 
by oxo-synthesis; fatty acid mono- or diglycerides, for example 
C.sub.12-18 coconut oil fatty alcohol, C.sub.16-18 tallow alcohol, 
C.sub.8-24 oxoalcohol, C.sub.16-18 tallow fatty acid monoglyceride; or 
from adducts of 1 to 6 mols of alkylene oxide with the fatty alcohols or 
fatty acid glycerides mentioned or with fatty acids, for example the 
adduct of 2 to 3 mols of ethylene oxide with C.sub.16-18 tallow fatty 
alcohol, the adduct of 4 to 6 mols of ethylene oxide with a mixture of 
C.sub.16-24 fatty acids, or the adduct of 2 mols of ethylene oxide with a 
mixture of C.sub.12-18 fatty acids. The sulfosuccinic acid esters are used 
in the form of their salts, preferably their sodium and/or ammonium salts. 
Suitable emulsifiers (B), which are used in combination with the 
sulfosuccinic acid esters (A), include the adducts of from 5 to 25 mols of 
ethylene oxide with C.sub.8-20 fatty alcohols or alkyl phenols, such as 
C.sub.12-18 coconut oil fatty alcohol+8 EO, C.sub.16-18 tallow fatty 
alcohol+20 EO, nonyl phenol+9 EO, or the sulfates of the adducts of 1 to 6 
mols of ethylene oxide with C.sub.8-20 fatty alcohols, fatty acids or 
fatty acid alkanolamindes, for example the sulfates of C.sub.12-18 coconut 
oil fatty acid ethanolamide+2 EO, C.sub.8-16 fatty acid ethanolamide+2 EO 
or C.sub.12-18 coconut oil fatty alcohol+5 EO, in the form of their alkali 
or ammonium salts, preferably their sodium salts. 
The sulfosuccinic acid esters are added to the tanning or retanning liquors 
together with the emulsifiers before, during or after addition of the 
tanning electrolytes. That is, the two agents are added together or 
separately at any point during the manufacturing process in which 
fatliquoring or preliminary fatliquoring is desired, and since the agents 
are compatible with the tanning liquor, there is no need to change liquors 
when tanning, pretanning, or retanning. The liquors are simply mixed 
together. The liquors are distinguished by their high stability. Very 
supple leathers and skins are obtained. Their grain stability is 
considerably improved by comparison with the sulfitation products normally 
used. 
In the process according the invention, the sulfosuccinic acid esters (A) 
and emulsifiers (B) may be used in the tanning liquor together with 
standard electrolyte-resistant fat-liquoring agents, such as sulfited 
oils, for example fish oil, or agents produced by sulfochlorination and 
subsequent hydrolysis of unsaturated fatty acid esters, such as tallow 
fatty acid methyl ester, or long-chain paraffins, for example 
chloroparaffin sulfonate. 
EXAMPLES 
I. Production Examples for Sulfosuccinic Acid Esters 
1. C.sub.16-18 alkyl sulfosuccinate, Na/ammonium salt 
192.3 g (0.72 mol) of oleyl cetyl alcohol (I.V. 50.5, OH No. 209) were 
introduced into a 2-liter three-necked flask equipped with a nitrogen 
inlet, stirrer and thermometer and reacted at &lt;80.degree. C. with 70.2 g 
(0.72 mol) of maleic acid anhydride. After an acid number of 155 had been 
reached, a solution of 69.5 g (0.37 mol) of sodium bisulfite in 615.5 g of 
water and 52.5 g of concentrated ammonia was added to the reaction product 
at around 60.degree. C., followed by stirring for 3.5 hours at 
60.degree.-65.degree. C. The end product was adjusted to pH 7 with ammonia 
water (10%). Appearance: milky, low-viscosity, highly stable suspension. 
2. Sulfosuccinate based on glycerin dioleate 
218 g (0.35 mol) of glycerin dioleate and 34.5 g (0.35 mol) of maleic acid 
anhydride were heated with stirring in a nitrogen atmosphere until an acid 
number of 80 had been reached. 35 g (0.18 mol) of sodium bisulfite 
dissolved in 300 g of water and neutralized with approx. 27 g of 
concentrated ammonia were then added and the mixture stirred for 1 hour at 
75.degree. C. A white emulsion having a solids content of 53% was 
obtained. 
3. C.sub.12-18 alkyl sulfosuccinate, Na salt. 
207 g (1 mol) of C.sub.12-18 coconut oil fatty alcohol (tech.) and 98 g (1 
mol) of maleic acid anhydride were stirred in a nitrogen atmosphere until 
an acid number of 185 had been reached and then reacted while stirring at 
75.degree. C. with a solution of 132.5 g (1.05 mol) of sodium sulfite in 
1020 g of water; time 1 hour. A paste containing approx. 30% of active 
sulfosuccinic acid esters solidifying at room temperature, was obtained. 
II. Application Examples in Leather Manufacturing 
4. Chrome tanning of napa (sheepskin) leather 
______________________________________ 
starting material: lined (unhaired) and skived 
(split) cowhide - about 2.5 mm. 
time 
Step Percent ingredient, processing sequence 
(minutes) 
______________________________________ 
Washing 300. water at 35.degree. C., drain liquor 
15 
Deliming no liquor, 45 
1.2 a buffer mixture of organic 
and inorganic acids, 
0.3 sodium disulfite, 
0.3 nonyl phenol + 10 E.O. 
Bating 1. enzymatic bate, drain liquor 
60 
Washing 300. water at 35.degree. C., drain liquor 
15 
Pickling 
70. water at 20.degree. C., 
10 
8. common salt, 
0.5 formic acid, 30 
0.8 sulfuric acid, 90 
then allow to stand 
overnight 
Tanning inventive agents, comprising 
30 
combined 
0.3 C.sub.16-18 fatty alcohol +20 E.O. 
with 1.7 C.sub.16-18 alkyl sulfosuccinate, 
preliminary Na salt 
fatliquoring 
8. chrome tanning composition 
60 
(25% Cr.sub.2 O.sub.3 /33% basic) 
0.5 MgO 300 
then retan, dye, fatliquor, and finish leather in usual 
______________________________________ 
manner 
In Examples 4 through 9, the column headed "percent" refers to the 
percentage of each ingredient by weight, based upon the dry weight of the 
starting material. 
5. Retanning of napa (sheepskin) leather 
______________________________________ 
starting material: chrome tanned cowhide - 1 mm thick 
time 
step percent ingredient, processing sequence 
(minutes) 
______________________________________ 
Washing 300. water at 45.degree. C., drain liquor 
15 
Retanning 
100. water at 45.degree. C., 
15 
and 2. chrome tanning composition 
fatliquoring (25% Cr.sub.2 O.sub.3 /33% basic), 
2. amphoteric auxiliary tanning 
composition 
0.7 sodium-aluminum silicate, then 
2. inventive agents, comprising: 
45 
3 parts of C.sub.16-18 fatty 
alcohol + 20 E.O., 
17 parts of C.sub.16-18 alkyl 
sulfosuccinate, Na salt 
Washing 300. water at 45.degree. C., drain liquor 
15 
then neutralize, dye, fatliquor, and finish leather in usual 
manner 
______________________________________ 
6. Chrome tanning of soft upper leather (cowhide) 
______________________________________ 
starting material: lined and skived 
cowhides - about 4 mm thick 
time 
step percent ingredient, processing sequence 
(minutes) 
______________________________________ 
Washing 300. water at 35.degree. C., drain liquor 
15 
Deliming no liquor, 45 
1.2 buffer mixture ("Rectil" EH)* 
0.3 sodium disulfite 
0.2 nonyl phenol + 10 E.O. 
Bating 0.5 enzymatic bate, drain liquor 
30 
Washing 300. water at 35.degree. C., drain liquor 
15 
Pickling 
70. water at 20.degree. C. 
10 
8. common salt, 
0.5 formic acid, 30 
0.8 sulfuric acid, 90 
then allow to stand 
overnight 
Tanning 0.5 inventive agents, comprising: 
30 
and 2 parts of nonyl phenol + 
preliminary 10 E.O., 
fatliquoring 3 parts of C.sub.12-24 fatty acid 
(+ 3 E.O.) sulfosuccinate, 
Na salt 
8.0 chrome tanning composition 
60 
( 25% Cr.sub.2 O.sub.3 /33% basic) 
0.5 MgO, final pH about 3.8 
300 
then neutralize, dye, fatliquor, and finish leather in usual 
manner 
______________________________________ 
Notes: *primarily amidosulfonic acid and ammonium sulfate. A trademark of 
Henkel KGaA, Duesseldorf, F.R. Germany 
7. Retanning of soft upper leather (cowhide) 
______________________________________ 
starting material: chrome tanned cowhide - 1.6 mm thick 
time 
step percent ingredient, processing sequence 
(minutes) 
______________________________________ 
Washing 300. water at 45.degree. C., drain liquor 
15 
Retanning 
100. water at 45.degree. C., 
15 
and 3. chrome tanning composition 
fatliquoring (25% Cr.sub.2 O.sub.3 /33% basic), 
3. amphoteric auxiliary tanning 
composition ("Pellupur" NB)*, 
1. sodium-aluminum silicate 
("Coratyl" G)** 
1. inventive agents, containing 
45 
2 parts of nonyl phenol + 
9 E.O. 
3 parts of C.sub.12-18 fatty acid 
(+ 2 E.O.) sulfosuccinate, Na 
salt 
Washing 300. water at 45.degree. C., drain liquor 
15 
then neutralize, dye, fatliquor, and finish is usual manner 
______________________________________ 
notes: 
*a condensation product based upon aromatic sulfonic acids. A trademark o 
Henkel KGaA, Duesseldorf, F.R. Germany 
**primarily zeolite A. A trademark of Henkel KGaA, Duesseldorf, F.R. 
Germany 
8. Production of leather for clothing 
______________________________________ 
starting material: pickled New Zealand sheepskin 
time 
step percent ingredient, processing sequence 
(minutes) 
______________________________________ 
De- 200. water at 38.degree. C., 
30 
greasing 
10. common salt, 
1. nonyl phenol + 10 E.O., 
scrape and weigh 
25. water at 38.degree. C., 
40 
4. nonyl phenol + 10 E.O. 
Pre- +50. water at 38.degree. C., 
20 
liminary 
5. common salt, then add 
tanning 
2. glutaraldehyde, then add 
40 
1. adipic acid (tech. grade), 
30 
3. sodium-aluminum silicate 
("Coratyl" G) 
+50. water at 38.degree. C., then add 
30 
+100. water at 45.degree. C., pH about 4, 
60 
rinse at 45.degree. C. until the liquor 
is clear 
Pickling 
80. water at 20.degree. C., 
10 
10. common salt, 
1. formic acid 30 
Pre- 2. inventive agents, comprising 
30 
liminary 1 part of C.sub.12- 18 fatty 
fat- alcohol (+ 5 E.O.) 
liquoring sulfate, Na salt 
1 part of C.sub.16-18 alkyl sulfo- 
succinate, Na salt, then add 
Tanning 
6. chrome tanning composition 
30 
(25% Cr.sub.2 O.sub.3 /33% basic) 
0.3 MgO, pH about 3.8 330 
then neutralize, retan, fatliquor and finish in usual manner 
______________________________________ 
9. Production of lamb velour 
______________________________________ 
starting material: washed and degreased lambskins 
quantity time 
step (g/l) ingredient, processing sequence, 
(minutes) 
______________________________________ 
Pickling 
60 common salt (liquor 30.degree. C.) 
10 
.5 C.sub.12-18 alkyl sulfate, Na salt 
5 
5 (ml) formic acid, drain liquor, 
overnight 
permit skins to drip-dry 
Tanning 50 common salt (liquor 30.degree. C.), then 
10 
and .5 formic acid, pH about 3.5, then 
5 
fatliquoring 
6. chrome tanning composition 
60 
(25% Cr.sub.2 O.sub.3 /33% basic), then 
6. chrome tanning composition 
60 
(25% Cr.sub.2 O.sub.3 /33% basic), then 
1.5 inventive agent (A) comprising 
60 
C.sub.12-18 alkylsulfosuccinate, Na 
salt, and 
1.5 inventive agent (B) comprising 
C.sub.12-18 fatty acid mono- 
ethanolamide (+ 2 E.O.)sulfate, 
added independently, then 
6. chrome tanning composition 
overnight 
(25% Cr.sub.2 O.sub.3 /33% basic), with 
periodic stirring, then 
-- alkalinize with Na.sub.2 CO.sub.3 to pH 
-- 
3.8-4, then 
-- after-run cold rinse, then 
180 
-- rack skin and leave 
1 day 
then dry, stake, degrease by machine, buff-dye, and finish in usual 
manner 
______________________________________