Note: Descriptions are shown in the official language in which they were submitted.
2tg4912
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GLYCINE-CONTAINING REDUCING SOLUTION
The present invention generally relates to the
art of permanent waving ("perming") of hair and, more
particularly, to novel reducing solutions containing
glycine that impart significantly higher retention of
tensile strength in hair that has been permed using the
reducing solutions of the present invention.
Permanent waving of human hair broadly involves
two steps. The first step is a reducing step which
involves an application of a reducing solution to hair
to chemically break the sulfur to sulfur or disulfide
cystine bonds occurring naturally in human hair. The
disulfide cystine bonds in human hair maintain the hair
shape or configuration. While the disulfide cystine
bonds are broken the hair can be rearranged into a
different configuration. The second step in the
permanent waving of hair is an oxidation step which
involves application of an oxidizing agent to restore
the disulfide bonds in the new rearranged configuration.
Reducing solutions useful for permanent waving
of hair contain a reducing agent. It is the reducing
agent that chemically breaks the disulfide bonds in the
hair. Examples of reducing agents useful in reducing
solutions include cysteamine, esters and salts of
thioglycolic acid, cysteine, and thiolactic acid.
Typical examples of reducing agents and reducing
3 solutions are taught in U.S. Patent No. 5,260,054.
The reducing step is generally carried out
under alkaline conditions. The rearrangement of the
disulfide bonds results from both the mechanical stress
put on the hair by mandrels or waving rods and from the
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action of the alkali. The alkali serves to swell the
hair by allowing the dissociated sulfur atoms generated
by the breaking of the disulfide bonds, to slip past one
another more easily under the stress applied by the
rods. Consequently, reducing solutions generally have a
pH value above about 8.
Generally, reducing solutions may also contain
other ingredients like surfactants, chelating agents, or
fragrances. Surfactants useful in reducing solutions
may be anionic~ cationic~ or nonionic. Examples of
surfactants useful in a reducing solution include
Laureth-23, and Poloxomar-188. Examples of chelating
agents useful in reducing solutions may include
ethylenediaminetetraacetic acid ("EDTA")~ as well as
salts and derivatives of EDTA.
Permanent waving can damage the structure of
the hair, especially if done frequently. This damage
can result in hair that has lost much of its strength,
thus becoming brittle and breaking easily.
The present invention is directed to reducing
solutions containing glycine that are useful in the
permanent waving of hair. It is an object of the
present invention to overcome the deficiencies of the
prior art mentioned above.
The present invention provides reducing
solutions that preserve much of the hair strength that
is normally lost as a result of perming hair. The
present invention is based on the discovery that the
addition of glycine into reducing solutions used in
permanent waving of hair results in permed hair having
increased strength over hair permed using reducing
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solutions not containing glycine. Generally, reducing
solutions of the present invention contain at least
about 0.5 percent by weight glycine.
Figure l is a graphical representation of hair
strength data obtained by measuring the hair strength of
a hair fiber before and after the hair fiber was treated
with a comparative sample composition.
Figure 2 is a graphical representation of hair
strength data obtained by measuring the hair strength of
a hair fiber before and after the hair fiber was treated
with an embodiment of the present invention.
Figure 3 is a graphical representation of hair
strength data obtained by measuring the hair strength of
a hair fiber before and after the hair fiber was treated
with another embodiment of the present invention.
Figure 4 is a graphical representation of hair
strength data obtained by measuring the hair strength of
a hair fiber before and after the hair fiber was treated
with yet another embodiment of the present invention.
The present invention is directed to reducing
solutions containing glycine.
Generally, the reducing solutions of the
present invention contain a functional amount of
reducing agent and sufficient alkali to give the
reducing solution a pH above about 8. Most preferably,
the reducing solutions of the present invention have a
pH of from 8.5 to 9Ø A functional amount of reducing
agent is any amount that allows the reducing solution to
be used effectively in the permanent waving of human
hair. These amounts may vary depending on the type of
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reducing agent used. The types and amounts of reducing
agents useful in the present invention are generally
well known to one of ordinary skill in the art. Most
preferably, the reducing agent is cysteamine.
It is believed that the use of cysteamine as
the preferred reducing agent in the composition would
result in less damage to hair than would the use of
thioglycolic acid or the salts of thioglycolic acid.
Cysteamine has a pK2 value of 8.3 and thioglycolic acid
and the salts of thioglycolic acid have pK2 values that
range from 9.2 to 10.6. The difference in pK2 values
indicates that cysteamine would be more fully ionized
than thioglycolic acid or the salts of thioglycolic acid
at a given pH above pH 8.0 and less than 9Ø It is
believed that the more fully ionized cysteamine (pH 8 to
9) forms and association complex with glycine (pK2 =
9.6) that thioglycolic acid or the salts of thioglycolic
acid cannot form in the same pH range. Since cysteamine
forms a complex with glycine, there is less free
cysteamine to react with the disulfide bonds of hair,
causing less damage to hair than free thioglycolic acid
or salts of thioglycolic acid.
Other ingredients may be added to reducing
solutions of the present invention. These additional
ingredients may include, for example, surfactants,
chelating agents, and fragrances.
Hair treated with reducing solutions of the
present invention maintain greater strength than hair
treated with similar reducing solutions but containing
no glycine. The following amino acids have been tested,
but do not appear to impart increased hair strength as
does glycine: lactic acid, alanine, glulamine, succinic
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acid, glycolic acid, serine, lysine, asparagine, and
adipic acids.
Generally, the reducing solutions of the
present invention contain at least about 0.5 percent by
weight glycine. Increasing the amount of glycine in a
reducing solution of the present invention results in
increased hair strength. However, higher amounts of
glycine in some embodiments may result in some loss of
curl efficiency. Consequently, lower amounts of glycine
can be used to impart sufficient hair strength without
compromising curl efficiency. Preferably, the reducing
solutions of the present invention contain from 0.5
percent by weight to lO percent by weight glycine. Most
preferably~ the reducing solutions of the present
invention contain from 0.5 percent by weight to 5
percent by weight glycine.
The method of making the reducing solutions of
the present invention is not critical. Methods for
making reducing solutions are well known in the art and
the addition of glycine to reducing solutions is easily
accomplished by anyone with ordinary skill in the art.
Example l
Table I shows the composition of one example of
an embodiment of the present invention ("Example l") as
well as a comparative sample ("Comparative Sample l").
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TABLE I
Percent by Weight
Ingredient
Example 1 Comparative
Deionized Water 70.96 75.36
Cysteamine HCL 11.50 11.50
Aqueous Ammonia (28% active) 5.64 5.64
10 Glycine 4.40 --
Versenol 120 (chelating agent) 2.00 2.00
Pluronic F-68 (surfactant) 2.00 2.00
Brij 35 (surfactant) 2.00 2.00
Dequest 2016 (chelating agent) 1.00 1.00
Fragrance 0.50 0.50
The effect these compositions have on hair
strength of treated hair was measured using a rhecneter
commercially available from Dia-Stron Limited. The
rheometer is a miniature tensile tester and is used in
applications where information on the elastic properties
or tensile strength of small fibers and other materials
iS required-
The rheometer was used to measure the break
load and break strain of untreated hair, hair treated
with Comparative Sample 1, and hair treated with Example
1- The break load is the amount of force, in grams of
force ("gmf"), required to break a sample. The break
load is the percent elongation of a sample at the
breaking point. For example, if an initial sample
length is 20.0 mm before measuring and the sample broke
at 31 mm~ then the sample was elongated 11 mm or 55
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percent of the initial sample length and the break load
is 55 percent.
The results of the rheometer measurements are
shown in Table II.
TABLE II
Treatment Break Load Break Strain
Composition (gmf) (percent)
Untreated 103 60.9
Comparative Sample 1 87 57.5
Treated with Example 1 126.5 65.8
For the untreated hair a break load of 103 gmf
and a break strain of 60.9% was measured. For the hair
treated with Comparative Sample l a break load of 87 gmf
and a break strain of 57.5% was measured. And for the
hair treated with Example l a break load of 126.5 gmf
and a break strain of 65.8% was measured.
While taking the measurements shown in Table
II, each hair sample was broken during the measurement.
Thus, each measurement shown in Table II was taken on a
different hair sample.
Examples 2-4
Table III shows four different compositions: a
comparative sample ("Comparative Sample 2") and three
examples of embodiments of the present invention. The
four compositions shown in Table III differ only in the
amount of glycine and water contained in each
composition.
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TABLE III
Percent by Weight
Ingredient Compar-
ative Example Example Example
Sample 2
Deionized Water 77.03 66.53 72.53 67.53
Cysteamine HCL ll.lO ll.lO ll.lO ll.lO
Aqueous Ammonia (28~) 5.87 5.87 5.87 5.87
Pluronic F-68 2.00 2.00 2.00 2.00
Dequest 2016 2.00 2.00 2.00 2.00
Isoascorbic Acid 2.00 2.00 2.00 2.00
Glycine 0.0 0.5 5.0 lO.0
The tensile strength of hair treated with each
of the compositions shown in Table III was measured on
the rheometer by the 20% method. In the 20% method,
single fibers of hair were mounted and stretched on the
rheometer to measure the force required to extend the
hair 20% of its original length. Tensile strength
(i.e., hair strength) is measured on the rheometer as
work expended in extending the sample. A higher
measured rheometer value indicates higher hair strength.
This 20% method allows the hair strength to be
measured without breaking the hair. Thus, the same hair
fiber can then be treated and re-measured on the
3 rheometer to determine the effect of the treatment on
hair strength.
Each of the four compositions shown in Table
III was tested using the 20% method to determine the
effect each composition has on the strength of hair
41,382-F -8-
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g
treated with the composition. For this test, hair
samples were soaked in tap water 24 hours prior to the
initial (baseline) measurement on the rheometer. After
the baseline measurement, each hair sample was removed
from the rheometer and placed in an individual glass
vial filled with tap water until the time of treatment.
The samples were allowed to stand for a minimum of 24
hours to allow the hair to return to its original shape.
Next, each hair sample was treated with one of
the four compositions of Table III. The treatment
process took place for 20 minutes at room temperature in
a bag. Each hair fiber was then neutralized with 2.0%
H22 in water.
The treated hair was then placed in a weighing
dish filled with tap water until the time it was re-
measured on the rheometer. The treated hair was then
mounted on the rheometer and measured. All hair fiber
samples tested were blond hair.
The results of the test using this 20% method
are shown in Table IV. These results are also graphed
in Figures l-4.
3o
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C-4 1, 382 - 1 0 -
` 2144312
.
, 1
For each of the four samples, the rheometer
measurement for the treated hair was subtracted from the
rheometer measurement for the untreated hair. This
difference between the measured value for the untreated
hair and the measured value for the treated hair
indicates loss of hair strength due to the treatment of
the hair fibers. The average of these differences was
computed for the ten hair fibers for each of the four
samples. The results of these computations are shown in
Table V.
TABLE V
Average Strength Loss
(Untreated - Treated)
Composition Loss
Comparative Sample 2 0.581
Example 2 0.495
Example 3 0.435
Example 4 0.214
As shown in Table IV, Table V, and in Figures
1-4, for each of the compositions tested, the treated
hair lost some strength versus the untreated hair.
However, hair treated with compositions containing
higher amounts of glycine lost less strength, on
average, than hair treated with the compositions
containing lesser amounts of glycine.
Table VI shows the composition of a
particularly preferred embodiment of the present
invention ("Example 5").
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TABLE VI
. Percent by
Ingredlent Weight
Deionized Water 73.99
Cysteamine HCL 11.36
Aqueous Ammonia (28X active) 3.65
Brij 35 (surfactant) 2.50
Dequest 2016 (chelating agent)2.00
Pluronic F-68 (surfactant) 2.00
Glycine 2.00
Isoascorbic Acid 2.00
Belmay 3069-3725V (fragrance) 0.50
Example 5
Example 5 was prepared according to the follwing
procedure:
l. The total amount of water was added to
beaker.
2. Pluronic F-68 was added to water in beaker.
Mix until completely dissolved.
3. Dequest 2016 was added to batch. The batch
was mixed until completely dissolved.
4. Glycine was added to the batch. The batch
was mixed until completely dissolved.
5. Mixing speed was reduced and Aqua Ammonia
(28%) was added to the batch. The remainder
of the batch was mixed continously at slow
speed.
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6. Cysteamine HCL was added to the batch. The
batch was mixed until completely dissolved.
7. Isoascorbic acid was added to batch. The
batch was mixed until completely dissolved.
8. The Brij 35 was weighed into a small beaker
and melted on a hot plate. The beaker of
liquid Brij 35 was removed from the hot
plate and the Belmay 3069-3725V fragrance
was added to it while mixing. The
fragrance/Brij 35 mixture was added to the
batch. The batch was mixed until completely
solubilized.
Note: Solution will be clear after the addition
of all ingredients and after thorough mixing.
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