Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an acidic shampoo compo-
sition. More particularly this invention relates to an acidic
shampoo composition having improved cleaning.
Acid side shampoos, i.e. shampoos with a pH of less
than seven, have been known and in fact there are a number of
shampoos currently on the market having a pH within the range
of 5 to 7. It is known that high alkaline shampoos tend to
damage hair and accordingly there has been a recent switch
towards shampoo compositions which are less alkaline.
U.S. Patents 2,289,004, 2,303,932, 2,599,665 and
2,892,756 describe acid side shampoo hair treating composi-
tions. These patents describe compositions having pHs with
the range of from 2 to 7 and indicate that damage to the hair
can be minimized by using a shampoo having a pH near the iso-
electric point of hair, i.e. pH 4.5.
Also there are a number of patents and publications
which describe the use of anionic detergents as the cleaning
agent in the shampoo composition. The most commonly used
anionic detergent is sodium lauryl sulfate. This detergent is
an effective cleaner for the hair and has reasonable solubil-
ity.
It has been found that an improved cleaning shampoo
composition can be prepared by incorporating 12.5 to 25~ by
weight of an anionic detergent selected from the group con-
sisting of M-lauryl sulfate, mixtures of M-lauryl sulfate and
M-lauryl sulfate plus from 1 to 10 moles of ethyleneoxide and
mixtures of M-lauryl sulfate and triethanolamine lauryl sul-
fate wherein M is selected from sodium, potassium and ammonium,
from 1.0 to 3.5~ by weight of an inorganic salt soluble in the
composition and from 0.25 to 1~ by weight of an acid selected
from citric acid, boric acid, hydrochloric acid, phosphoric
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acid, ascorbic acid and mixtures thereof, the composition hav-
ing a pH within the range of 3 to 4.5 and a viscosity within
the range of from 4000 to 15,000 centipoise.
It is surprisingly found that the composition having
an increased viscosity performs significantly better than a
similar composition having a lower viscosity and that composi-
tions having lower pHs perform better than compositions having
higher pHs, furthermore the compositions having lower pH and
higher viscosity perform better than the similar compositions
having either higher pH or lower viscosity. The improvement
in performance appears to be synergistic since the combined
effects of increased viscosity and decreased pH are exceeded
by the composition having increased viscosity and decreased
pH.
The prime cleaning component of the composition of
the present invention is the anionic detergent. Anionic de-
tergents useful in the present invention are selected from the
group of M-lauryl sulfate, mixtures of M-lauryl sulfate and M-
lauryl sulfate plus 1 to 10 moles of ethyleneoxide and mixtures
of M-lauryl sulfate and triethanolamine lauryl sulfate wherein
M is selected from sodium, potassium and ammonium. The total
anionic detergent present in the composition in the present
invention should be within the range of from 12.5 to 25% by
weight and particularly within the range from 14 to 21~ by
weight anionic detergent. When mixtures of M-lauryl sulfate
are used with the other anionic detergents as described above,
the mixture should be within the range of from 0 to g parts
other anionic detergent per 1 part M-lauryl sulfate. The pre-
ferred M-lauryl sulfate for use in the composition of the
present invention is ammonium lauryl sulfate.
The second component of the composition of the pres-
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ent invention is an inorganic salt. The primary function of
the inorganic salt is to provide free electrolyte which in-
creases the viscosity of the composition~ Within a certain
range of inorganic salts, the viscosity of the composition in-
creases, however, above or below the range, i.e. from 1.0 to
3.5% by weight, the viscosity of the resultant sha~poo compo-
sition decreases. It is within this maximum range of visco-
sity that the performance properties of the shampoo are most
surprising. Any non-toxic inorganic salt which is soluble in
the composition of the present invention i~ suitable such as
sodium chloride, potassium chloride, lithium chloride, ammoni-
um chloride, sodium citrate, potassium citrate, lithium ci-
trate and ammonium citrateO The preferred inorganic salts are
ammonium chloride, sodium chloride and potassium chloride.
The most preferred salt is ammonium chloride. As noted above,
these salts may be present in a range of from lo O to 3.5~ and
is preferred that the salt be present in the range of about
1.4 to 2~75% by weight of the total composition~
The viscosity of the composition should be within
the range of 4000 to 15,000 centipoise and preferably within
the range of 5000 to 10,000 centipoise. The viscosity is mea-
sured using a Brookfield viscometer equipped with a number ~V4
spindle set at 30 ~PM.
The third componen~ of the present invention is an
acidifying agent. The prime purpose of these acidifying or pH
control agents is to lower the pH of the resultant composi-
tionO Although any suitable acid can be utilized to control
the pH of the composition it has been found particularly ac-
ceptible to use the following acids: citric acid, boric acid,
hydrochloric acid, phosphoric acid, ascorbic acid and mixtures.
These acids tend to have a buffering effect within the desired pH
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range when used in combination with the lauryl sulfate anionic
detergent and the inorganic salt. Although the exact amount
of the acid added is not critical, it is important to add suf-
ficient acid to the composition so that the pH is maintained
within the range of from 3 to 4.5 and preferably within the
range of 3.3 - 4Ø Generally from 0.25 to 1% by weight is
satisfactory.
The bulk of the composition of the present invention
comprises water. Substantially any water can be utilized in
the composition although good manufacturing procedures require
that the water be deionized and substantially free of ma~or
contaminants and impurities.
In addition to the above noted ingredients composi-
tions of the present invention can include a number of other
conventional additives including dyes, pigments, pearlessing
agents, perfumes, preservatives and the likeO These ingredi-
ents should be present in the composition preferably in com-
bined amounts of less than 5% and in indlvidual amounts of
less than 2% each~
The composition of the present invention will now
be illustrated by way of the following examples which are for
the purpose of il~ustration only and are in no way to be con-
sidered as limiting.
EX~MPLE I
A shampoo composition having the following composi-
tion was prepared: ammonium lauryl sulfate (28~) 60%, ammonium
chloride 2.5%, citric acid 0.35%, fragrance 0.5~, formalin
0.13~, color QS, deionized water to 100%. The composition as
prepared had a pH of 3.65 and a viscosity of 10,000.
~omparative Ex mples I, II and_III
Compositions similar to the composition in Example I
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were prepared with the exception that the level of citric acid
and ammonium chloride was varied as shown in Table I
TABLE I
Example Citric Acid NH4Cl pHVisc ~ L
I Or 35 2.5 3.6510,200 254
Comparative Exc 1 ---- 0.5 600 29 180
Comparative Ex. 2 ~~~~ 2.5 506 10>800 199
Comparative Ex, 3 0. 35 Oo 5 3~ 7 45 220
The compositions of the comparati.ve Examples I, II
1.0 and III and Example I were all tested on about 30 women in
half head tests comparing 2 different formulations. ~he com-
position of Example I was preferred over each of the compara-
tive examplesO Furthermore, each of these compositions was
tested in a Terg-0-Tometer for cleaning. The cleaning scores
~L for Example I were higher than the cleaning scores from
comparative exam41.es I, II and III and the improvement in
cleaning from comparative example I to Example I is greater
than the combined increase from comparative Example I of com-
parative Examples II and III.
EXAMPLES 2 - 4
The following shampoo formulations were preparedO
Example 2 Example 3 Example 4
Ammonium Lauryl Sulfate (28%) 50.0 60.0 75.0
Ammon~um Chloride 2 75 2,0 1.4
Gitric Acid 0.35 0035 0.35
Color qs qs qs
Fragrance qs qs qs
Formalin qs qs qs
D.I. Water qs _ qs _ qs
100.0 .100.0 100.0
pH 306 3.6 3.6
Viscosity 6000 6Goo 6000
Each of the abo~e formula per~ormed in a manner simi-
lar to the formula of Example 1.
