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Патент USA US2403937

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Patented July 16, 1946.
.umrroys'rA'rl-zs PATENT‘ OFFICE ?
Herbert August Lubs, Wilmington, DeL, assignm
to E. ii. du Pont de Nemours 85 Company, Wil
1 mington, Del, a. corporation of Delaware
No Drawing. Application December 30, 1943,
Serial No. 516,285
4 Claims. (or. 167-871)
This invention relates to ‘the modi?cation of
lreratinous materials, particularly wool-or hair,
indicated by a quantitative determination of the
amount of formamidinesul?nlc acid consumed, or
by a quantitative analysis of the number of di
sul?de groups which have been converted to the
sulfhydryl groups. The product is washed with
with formamidinesul?nic acid.
A keratinous material, e. g., Wool or hair, which
has been treated with some agent capable of rup
turing the disul?de linkages acquires certain de
sirable characteristics such as shrinkproofness,
susceptibility to permanent set, and sensitivity to
alkali. Inorganic sul?des, sul?tes and cyanides
a suitable solvent such as water and/or alcohol
and then dried in the air.
The more detailed practice of the invention is
illustrated by the following examples, wherein
have been used for this purpose but are known 10 parts given are by weight. There are, of course,
to degrade the keratinous material. Certain
mercaptans have been suggested as treating
agents in alkaline solution but these are disad
vantageous because of their toxicity, volatility,
insolubility in water, and disagreeable odor.
Thioglycolic acid is known to convert the disul
iide groups in wool to sulfhydryl groups but has
the disadvantage of being strongly acid and
many forms of the invention other than these
speci?c embodiments.
Example I
A solution of ,formamidinesul?m'c acid is pre
pared by adding 1172 parts of a 3% hydrogen
peroxide solution to 39.4 parts of thiourea dis
solved in 289 parts of water. The reaction mix
ture is maintained at a temperature below 10° C.
therefore corrosive to metal equipment. Further
ore, wool or hair treated with this compound 20 during the addition of the hydrogen peroxide.
This solution is adjusted to a pH of 8.2 by the
acquires an unpleasant odor.
addition of concentrated ammonium hydroxide
This invention has as an object the provision
and bu?‘ered at a pH of 8.25 with 5,000 parts of a
of a process for modifying the physical and chem
0.2 molar disodium acid phosphate solution.
ical properties of keratinous materials. A further object is a. process for reducing the shrinkage 25 Forty parts of wool serge is suspended in the
buffered solution of formamidinesul?nlc acid at
tendency and increasing the reactivity toward
room temperature (20-25° C.) for 24 hours, then
alkali oi’ keratinous materialsin particular wool.
washed with water and ethanol and air dried.
A still further object is a process for permanently
The treated wool gives a strong sodium nitro
setting hair, e. g., permanently waving, curling,
prusside test for sulfhydryl groups and is more
or delrlnking hair. Another object is to provide
soluble in dilute alkali than the untreated wool.
a wool containing sulihydryl groups and which
The conversion of disul?de linkages is nearly
does not have disagreeable odor characteristics.
Other objects will appear hereinafter.
Example II
These objects are accomplished by the follow
ing invention wherein a keratinous material, in
A solution containing 10 parts of formamidine
particular wool or hair, is reacted with formami
sul?nic acid and 400 parts of water is adjusted
dinesul?nlc acid
to a pH of 8.6 by the addition of ethanolamine
and bu?lered at a pH of 8.5 with 600 parts of a
0.2 molar disodium acid phosphate solution. Five
parts of wool serge is suspended in the solution
in aqueous alkaline solution until a substantial
at a temperature of 30° C. for 16 hours. After
proportion, preferably at least about 25%, of the
thoroughly washing with water and ethanol, the
disulfide groups of said keratinous material have‘
treated wool gives a strong sodium nitroprusside
been converted to suifhydryl groups.
test for thiol groups and is more soluble in dilute
In the preferred method of carrying out the
alkali than untreated wool. The conversion to
process of this invention, wool fabric is immersed
thiol was nearly quantitative.
in a mildly alkaline solution, that is a solution
The treated wool prepared as above and con
having a pH of from just above the neutral point
taining free thiol groups is suspended in a solu
to 8.5, containing formamidinesulfinic acid. The
tion containing 600 parts of methanol, 20 parts
solution may be bu?ered if desired with a suitable
of trimethylene dibromide and 400 parts of a
buffer solution, for example, disodium acid phos
citric acid-disodium acid phosphate buffer solu
phate buffer solution. The reaction is then ‘al
tion (pH 8.0) at a temperature of 20-25° C. ‘for
lowed to proceed for a period of 10-24 hours at a
48 hours. After ‘this treatment the wool gives
temperature of 20-50” C. The reaction is inter
a negative test for sulfhydryl groups and shows
rupted at any desired degree of completion as 55 no apparent solubility in dilute alkali indicating
reaction of the sulfhydryl groups with the tri
alent to about 1.3 to 2.1 parts or tormamidine
methylene dibromide.
Keratinous materials which may be used in the
process of this invention include wool in the form
of ?bers, threads, yarns, fabrics, or wool waste;
various types of animal hair such as camel hair,
sulnnic acid to one part0! wool or hair.
Any alkaline agent giving the desired pH can
. be used, including inorganic or organic bases or
mohair, horsehair, cattle hair, hog bristles, hu
basic salts, in combination, ii’ desired, with suit
able bu?‘ers. The nitrogen bases, for example,
ammonia, alkylamines, e. g., diethylamine; hy
man hair; and. additional keratinous materials,
droxyamines, e. g., mono-, di-, or tri-ethanol
for example, chicken feathers, fur, animal hooi's,
amines; and quaternary ammonium hydroxides,
10 e. g., tetramethylammonium hydroxide are partic
horns, and horn tips, etc.
An important application of the process de
ularly suitable. The pH of the alkaline solution
scribed in this invention is the permanent waving
is preferably maintained at from just above the
or, alternatively, dekinking, of human hair and
neutral point to 8.5, i. e., from just above that
animal hair. Treatment of hair with form
amidinesul?nic acid reduces the disul?de cross
links in the keratin molecule to thiol groups.
When reduced, the hair is more amenable to
of the salt to that of the salt plus alkali to a pH
oi’ 8.5. Conversion of the disul?de groups in the
wool or hair to the sulfhydryl groups by means of
i'ormamidinesul?nic acid does not occur in acid
solution, e. g., that of an aqueous formamidine
sul?nic acid which has a pH of 2-3. An alkaline
solution of pH above 8.5 tends to damage the
wool or hair by degradation. The pH can be
maintained at any point within the preferred
range by use of suitable buffer solutions as, for
shaping than untreated hair because splitting of
the disul?de crosslinks relieves stress in the kera
tin molecule.
In order to obtain a permanent
set, the reduced ?ber is formed in any desired
shape, as by means of a curler, and while main
tained in this shape, is subjected to an oxidizing
or other crosslinking treatment to reform cross
example, by disodium acid phosphate.
links between the keratin molecules. Suitable 25
Any temperature between 0° C. and 100° C. can
oxidizing treatments include heating the reduced,
be employed although the best results are ob
shaped ?ber in the presence of air or oxygen or
tained at 25-50° C. The reaction may be con—
reaction with hydrogen peroxide solutions. Suit
tinued until substantially all of the disul?de link—
able crosslinking reagents include alkylene di
ages are reduced, as indicated by analysis for
halides, dibasic acid chlorides, etc. The recross 30 thiol groups. Ordinarily a period of 1-24 hours
linked hair retains the shape in which it was
gives a practical degree of reaction, and in many
formed prior to the crosslinking treatment where
instances 10-16 hours is su?icient. The shorter
as untreated hair, subjected to the same shaping
reaction times are preferred, as degradation of
treatment, does not retain a permanent set. By
the keratinous material is minimized thereby.
treating hair of undesired, excessive curliness in 35 The product produced by application to wool
a similar manner, employing a curler of reduced
of the process of this invention are suitable for
curliness, or even a hair retaining device having
subsequent treatment with crosslinking agents
little or no curling effect, the curl may be reduced
such as organic and inorganic dihalides, metallic
salts, and oxidizing agents and for use in the
The formamidinesul?nic acid used in this proc ‘0 preparation 01' shrinkproof and alkali-sensitive
ess can conveniently be prepared from thiourea
wool textiles. For example, any of the cross
and hydrogen peroxide by the process described
linking agents in Salzberg application Serial No.
in U. S. Patent 2,150,921. The formamidinesul
438,509, ?led April 10, 1942, can be reacted with
?nic acid can, be isolated and added separately
wool which has been subjected to the process
to the alkaline reaction mixture or it can be pre 45 or this invention and contains sulfhydryl groups.
pared directly without isolation from hydrogen
A particular advantage or this invention is the
peroxide and thiourea in the treating solution.
fact that wool or hair which has been treated
In carrying out of the process of this invention
with formamidinesul?nic acid to convert the
at least one mol or more of formamidinesul?nic
di-sul?de groups to sulfhydryl groups does not at
acid per disul?de group in the wool or hair must 60 the same time acquire an objectionable odor as
be used in order to obtain suitable modi?cation
in processes using, for example, thioglycolic acid
or even eliminated.
of the wool or hair to show diiferences in prop
erties over the untreated wool or hair. Higher
proportions of the sul?nic acid up to the limit of
to accomplish this result.
The above description and examples are in
tended to be illustrative only. Any modi?cation
its solubility in the alkaline solution are also 55 of or variation therefrom which conforms to the
suitable. Ordinarily 25-40 mols of formamidine
- spirit of the invention is intended to be included
sul?nic acid per disul?de linkage in the wool are
within the scope of the claims.
used to obtain adequate alkali solubility of the
Whatisclaimed is:
wool and reduction in the shrinkage tendencies.
1. A process which comprises treating a kerat
The number of disul?de linkages in the wool 60 inous material with an aqueous alkaline solution
. may be calculated from the per cent 01' sulfur in
or at least one part by weight, per 19 parts by
weight of the keratinous material, of formami~
the wool on the basis of the group weight of the
disul?de linkage as 64. Thus with a wooi con
dinesuliinicacid. I
taining 3.1 grams of sulfur per 100 grams of wool
2. A process which comprises treating ‘wool
there would be one disul?de linkage (molar basis) 65 with an aqueous alkaline solution having a pH
not greater than 8.5 of at least one part by
weight, per 19 parts by weight of the wool, of‘
an‘ alkali Iormamidinesul?nate and con?nuing
the reaction until a substantial proportion of the
or 2060 grams of wool. Since the molecular 7o diml?de nouns
_ .o! the wool are converted to
weight of. formamidine-sul?nic acid is 108 there
thiol groups.
must be used 108 grams of formamidine-sul?nic
_ _ 3. A process which comprises treating a kerat
acid per 2060 grams of keratinous material such as hair or wool or 1 gram per 19 grams of wool.
The 25 to 40 mols per disul?de linkage is equiv
inous material with an aqueous alkaline solution
or at least one part by weight, per 19 parts by
75 weight of the keratinous material, or rormami
dinesul?nic acid and treating the so treated keuntil' a substantial portion of the disui?de groups
ratinous material with an alkylene dihalide.
oi the hair are converted to thioi groups and
4. A process which comprises treating hair with
then, while maintaining the hair in a suitable
an aqueous alkaline 'solution having a pH not
condition of curl,-subjecting the hair to a mild
greater than 8.5 of at least one part by weight, 5 oxidation.
per 19 parts by weight of the hair, or an alkali
iormamidinesul?nate, continuing the reaction
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