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Description  |
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BACKGROUND
1. Field of Invention
Detergent bars.
2. Description of the Prior Art
The ideal toilet bar should have certain characteristics. For example, a
toilet bar should possess good detergency when used on the skin and other
surfaces in all kinds of water including hard, soft, sea, cold and hot. It
should also exhibit excellent lathering qualities in all types of water
and be mild and non-injurious to the skin. It should also have a pleasing
appearance, rinse off easily and have a pleasing feel after use. The
toilet bar itself should exhibit little or no tendency toward softening,
blooming, crystallizing, cracking, drying or decomposing under storage
conditions, and further have the ability to be produced in standard
soap-making equipment.
Toilet bars prepared from soap have many of the aforementioned qualities,
but as a class generally are deficient in one or more aspects and
particularly with regard to lathering qualities under varying water
conditions.
The addition of a synthetic detergent to soap to improve performance in
hard and cold water has been practiced for many years, but the major
objection to such combinations still resides in lather characteristics.
On the other hand, bars made principally of non-soap synthetic detergent
are not satisfactory due to high hydroscopicity, unsatisfactory solubility
characteristics, extreme defatting action on the skin, and lack of
lubricant effect usually associated with soap, poor working properties in
standard soap machinery, brittleness and poor cohesion or excessive
softness of the bar itself. For example, alkyl benzene sulfonates are in
general excellent from the standpoint of being able to produce lather in
hard water, but, when used by themselves, result in detergent bars which
are much too soft and sticky. Accordingly, in order to correct these
deficiencies, the prior art suggests incorporation of various binders and
fillers; however, bars so prepared still do not have the feel and other
properties desirable in a toilet bar. In addition, bars made containing
such constituents are difficult to process in conventional equipment.
Normally alkene sulfonates made by adding SO.sub.3 to an .alpha.-olefin,
although being much harder than alkyl benzene sulfonates, become very
sticky when small percentages of water are incorporated in a formed
detergent bar. As a consequence, bars made from these materials are also
very difficult to process in the usual soap-making equipment, and
additionally have a tacky after-feel on the hands and also exhibit a wear
rate which is extremely high, and thus are undesirable notwithstanding the
fact that the lather evolved is of excellent quality.
Other synthetic detergents such as alkyl sulfates, sarcosinates, mono-alkyl
succinates, coco methyl tauride and the like, although offering many
advantages, are either too harsh in the ranges that they lather, require
critical conditions to plod successfully, or are too expensive to be used
as the main ingredient in detergent bars.
The alkane sulfonates, particularly in the C.sub.8 -C.sub.18 molecular
weight range have also been suggested for use in detergent compositions.
These materials are hard, at least as mild as soap, and will tolerate up
to 25% water without becoming sticky. When used by themselves, however,
even with 25% water these materials do not possess the desired plasticity
characteristic of soap. Thus, they are difficult to process in that they
are too hard to plod and stamp successfully. Moreover, the quality of
lather evolved leaves much to be desired in volume and in creaminess. In
order to correct these defects, the prior art (Canadian Pat. No. 636,022;
U.S. Pat. No. 3,442,812; and U.S. Pat. No. 2,781,321) suggests
incorporation in addition to the primary alkane a fatty acid plus other
optional ingredients. It has been found, however, that when toilet bars
are prepared in accordance with this prior art, the resulting product
suffers severely in lathering characteristics and may be quite mushy.
SUMMARY OF THE INVENTION
An inexpensive, synthetic detergent toilet bar is provided having superior
lathering properties under all water conditions, which is mild and has a
soap-like after-feel to the skin, which is non-mushing under conditions of
use and is readily processed with conventional soap-making equipment by
incorporating in selected proportions an alkane sulfonate containing 12
carbon atoms in the alkyl chain or a mixture of alkane sulfonates
averaging 12 carbon atoms in the alkyl chain, a superfatting agent
comprising natural or synthetic fatty acids containing 12 carbon atoms or
mixtures of said acids averaging 12 carbon atoms and a binder modifier
selected from the group consisting of hydroxyalkane sulfonates, acyl
(C.sub.10 -C.sub.16) isethionates, alkylmethyl taurides,
hydroxyalkylmethyl taurine, alkyl sulfates, alkyl phosphates, alkyl
phosphonates, alkyl sulfosuccinates, mono-alkyl succinates and maleates,
alkane disulfonates and alkene sulfonates. The bar so provided has a
composition comprising, based on the actives present, of about 40% to
about 80% by weight of the alkane sulfonate, about 5% to about 35% of a
natural or a synthetic fatty acid, and 5% to about 30% of a binder
modifier, and based on the total weight of the bar 5% to about 25% water.
DESCRIPTION OF THE INVENTION
I have found that a relatively inexpensive and readily available synthetic
detergent material, which by itself does not make a good toilet bar, can
be utilized in accordance with the present invention to provide a toilet
bar which exhibits extraordinary qualities of lather evolution and
creaminess, has a low wear rate, is readily processable and does not mush
under conditions of use.
In accordance with the teachings of the present invention, toilet bars of
improved performance qualities may be prepared by combining a select group
of alkane sulfonates (A) with a select group of superfatting agents (B),
and specific binder modifier (C) in critical proportions indicated by the
cross-hatched area of the triangular graph of FIG. 1.
FIGS. 1-4 graphically illustrate the present invention. FIG. 1 illustrates
the workable ranges of active components of the detergent toilet bar of
the present invention. The proportions of the active components (A), (B)
and (C) comprising the bar are shown in the equilateral triangle. When the
bar contains 100% alkane sulfonate (A), the point representing this
composition is the top apex of the triangle. Similarly, the point
representing 100% binder modifier (C) is the right hand apex and the point
for 100% superfatting agent (B) is the left hand apex. A composition
containing equal parts of the three components is represented by point O.
It is thus obvious that any composition containing the three components
may be represented by a point on the triangular graph of FIG. 1.
FIG. 2 is also a triangular graph indicating lather speed ratings of the
detergent bars at different compositional levels set forth in FIG. 1. More
specifically, in FIG. 2 the speed of lather ratings is superimposed on the
compositional points of FIG. 1. For example, lathering properties (speed)
were rated from 0-10 as will hereinafter be explained. In addition,
compositions containing a speed of lather rating of 9 or higher are
conveniently delineated, as shown within the cross-hatched area of
triangular graph of FIG. 2.
FIGS. 3 and 4 indicate creaminess and lather volume ratings corresponding
to compositional points; satisfactory creaminess and lather volume being
signified by a value greater than 8 and signified by cross-hatched areas.
Thus the graphs presented by FIGS. 1-4 permit one to superimpose ratings
for performance parameters upon compositional points. Where the areas of
the desired characteristics overlap, one can select a range of
compositions in which all desirable attributes are simultaneously achieved
and even when areas do not overlap, at least a compromise can be
judicially determined.
The alkane sulfonates (A), which form the principal ingredient of the
synthetic detergent bars of the present invention, are alkali metal,
magnesium or ammonium salts of a commercial alkane sulfonate made for
example by the addition of sodium bisulfite to linear Ziegler
.alpha.-olefins or alkane sulfonates made from .alpha.-olefin derived from
cracked wax and thus contain from about 85% to 95% active alkane
sulfonate, the balance being sodium sulfate and related inorganic salts.
In addition to the critical proportions of alkane sulfonate required to
form the detergent bar of the present invention, the length of the alkyl
chain of the alkane sulfonate is also quite critical. Thus it is essential
that the alkyl chain contain about 12 carbon atoms or comprise a mixture
of alkane sulfonates having varying chain lengths of about 8 to about 16
but averaging 12 carbon atoms.
In addition, the position of the polar sulfonate group on the hydrocarbon
chain is important. The bulk of the polar group should be in the No. 1
position, but a small proportion may be in the 2 or 3 position. For
example, a completely random distribution of the polar groups in the
hydrocarbon chain is completely unacceptable, since such a distribution
favors a mushy product. Thus the alkane sulfonates employable in the
present invention are essentially of the primary and secondary type.
The superfatting agents (B), which also form an important ingredient in the
synthetic detergent bar of the present invention, are derived from natural
or synthetic fatty acids which also have a chain length of 12 carbon atoms
or comprise mixtures of said acids containing chain lengths averaging 12
carbon atoms. However, when mixtures are used, it is important that the
major proportion not contain fatty acids having a chain length of above 16
carbon atoms or below 8 carbon atoms. Thus, so long as the natural or
synthetic fatty acids have the chain lengths aforementioned, any of the
fatty acids commonly found and utilized in soap bar toilet detergents may
be utilized.
The third ingredient (C), which is required in forming the detergent bars
of the present invention, are binder modifiers which are solids at room
temperature and comprise alkali metal, magnesium or ammonium salts
selected from the group consisting of:
C.sub.12 -c.sub.16 hydroxyalkane sulfonates (wherein the hydroxyl group is
removed at least 1 carbon atom from the sulfonate group),
C.sub.10 -c.sub.16 acyl isethionates,
C.sub.10 -c.sub.16 alkylmethyl taurides,
C.sub.10 -c.sub.16 hydroxyalkylmethyl tauride,
C.sub.12 -c.sub.18 primary alkyl sulfates,
C.sub.12 -c.sub.16 primary alkyl phosphonates and phosphates,
C.sub.12 -c.sub.16 mono-alkyl succinates and maleates,
C.sub.6 -c.sub.14 dialkylsulfosuccinates,
C.sub.16 -c.sub.20 alkane disulfonates, and
C.sub.8 -c.sub.18 alkene sulfonates.
The choice of binder modifier within the group enumerated above is quite
important. More specifically, certain agents commonly found in detergent
bars cannot be employed in the bars of the present invention. For example,
the presence of even small amounts of alkylaryl sulfonates, carbowaxes and
polyethylene glycol monostearates will either liquefy or unduly soften the
bar. Similarly, use of certain higher fatty acids such as stearic acid
will severely depress lather and fatty acid alkanolamides will cause
discoloration.
In addition to the specifications for individual components of the
detergent bars of the present invention, there are other strict
requirements which must be met when the components are combined. The most
important of these is pH. Suitable bars can only be made when the pH
ranges from about 4.5 to 9.5. Above pH 9.5, the bar rapidly losses its
lathering characteristics. This appears to indicate that the free fatty
acid is changed into a soap and the soap so formed interferes with lather
development in combination with the alkane sulfonate and also adversely
affects plasticizing characteristics. Bar pH is particularly important
when alkyl sulfates are employed as an ingredient in which case the pH
should be greater than 7, otherwise the alkyl sulfate will rapidly
hydrolyze.
Almost as important in lather development as is pH, is the chain length of
the detergents and fatty acids. For example, the synthetic detergent bars
of the present invention can tolerate only minor amounts of alkane
sulfonates, fatty acids or binder modifiers having carbon chain lengths
above C.sub.16 without significant loss of lather volume. An equal effect
will be noted in regard to mixtures of alkane sulfonates or fatty acids
having significant amounts of chain lengths of less than 10 carbon atoms.
I have found that it is very advantageous to use mixtures of fatty acids
and alkane sulfonates having chain lengths of between 10 and 14 in
proportions sufficient to provide an average of 12 carbon atoms. When such
proportions are employed, a synergistic phenomenon has been noted; the bar
performs better than when the chain length is 12.
Bars were tested to confirm the superior properties obtained when prepared
in accordance with the present invention. For example, the speed and
magnitude of lather evolution of a detergent bar having the composition as
determined by point X of FIG. 1, as compared with two commercial toilet
bars, is set forth in Table 1.
Experienced hand lathering evaluators were asked to compare conventionally
made toilet bars with toilet bars made in accordance with the teachings of
the present invention. Each evaluator was asked to use his standard method
of hand lathering when using each type of bar. The evaluator was required
to wash with each bar at least three times to establish maximum volume of
lather obtainable with it. The speed of lather was then determined by
measuring in triplicate the elapsed time to reach the maximum volume. This
time in seconds was recorded.
The procedure used for measuring the volume of lather was as follows:
Each evaluator used a washbowl in which to wash hands and the lather
produced was collected in a separate graduated cylinder. Each evaluator
used each bar three times in order to obtain an average volume of lather
for that particular bar.
TABLE 1
______________________________________
Subject*
Subject*
1 2 3 1 2 3
Seconds to
ml. of
No. of Maximum Lather
Bar Subjects Lather Evolved
______________________________________
Composition of
3 4 3 4 187 430 150
Point X of Figure 1
**Commercial
3 5 7 5 157 223 113
Detergent Bar
***Commercial
3 8 11 15 127 113 97
Soap Bar
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*Readings are averages of 3 determinations in 105.degree. F (tap water of
110 ppm hardness as CaCO.sub.3)
**50% sodium acyl isothionate
***Based on 80/20 tallow/coco soap
In order to further demonstrate the advantages of detergent bars prepared
according to the present invention, the bars were tested to determine wear
rate and resistance to mushing. Mush is a condition in which a used bar
does not dry to its original firmness but retains a soggy outer layer.
Mush was determined in the laboratory by subjecting the bar to hand
washing conditions for 45 seconds in order to produce an in-use surface
whereupon the bar was supported on an immersion rack and immersed in tap
water at 75.degree. F for a period of about 3 hours and then removed from
the water and permitted to dry overnight. Mush was then measured by
squeezing the bar firmly between the thumb and index finger, penetrating
through the soggy outer layer until a firm base was reached and grading as
follows:
N -- nil
T -- trace
S -- slight
M -- moderate
C -- considerable
The toilet bars were also tested to determine wear rate by subjecting them
to conditions of use by submerging in water at 105.degree. F, removing the
bar from the water, and rotating the bar 20 times between the hands and
repeating the procedure 2 times for a period totaling 40 rotations per
wash. The test was repeated 4 times during the day for a period of 2 days,
whereupon the soap bars were permitted to dry and the dry weight of the
bar, after the tests, compared with the weight of the bar prior to use.
Table 2 indicates the mush value and wear rate of a detergent bar having
the composition as determined by point X of FIG. 1 as compared with two
commercial toilet bars.
TABLE 2
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Bar Mush Wear Rate
______________________________________
Composition of Point X
N 2.62 .+-. .153
of Figure 1
*Commercial Soap Bar
N 2.55 .+-. .390
**Commercial Detergent Bar
M 3.40 .+-. .254
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*Based on 80/20 tallow/coco soap **50% sodium acyl isothionate
As important as are use characteristics in determining the value of a
formulation so are the properties which play a role in regard to the
ability to properly process the bar. For example, it is possible to obtain
a bar which possesses all the attributes of an ideal bar in respect to
lather, wear rate, etc., but yet is unsuitable because it exhibits poor
processing characteristics. More particularly, the composition may either
plod poorly or exhibit poor stamping properties. The former characteristic
relates to plasticity and the latter to adhesion and cohesion. For
example, when cohesion is not properly adjusted, the bar powders or cracks
during stamping or upon drying. Table 3 sets forth just a few of the
compositions prepared in conjunction with the instant invention and
demonstrates criticalities regarding proportion of ingredients as
exhibited by the resulting effect on plodding, stamping and lather
properties.
The ingredients (A, B and C) may be combined and formulated into toilet
bars in accordance with any conventional method. For example, the
essential ingredients may be first homogeneously blended together and then
admixed in a chip mixer with other non-essential ingredients and water in
an amount sufficient to form a product having a water content based on the
total weight of the bar of about 5-25%. The mixture is then milled on a
roller mill, plodded into logs, cut and finally stamped into bars.
Alternatively and preferably, the essential ingredients are first
co-dissolved in a water-solvent system. The water-solvent system which can
be used in the present invention, includes water and a solvent which can
be readily mixed with water and will co-dissolve the detergent and the
plasticizer of the present invention. Examples of such solvents are methyl
alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, acetone and/or
mixtures of these with each other or related water soluble, low boiling
point solvents. The volume ratio of water to solvent is preferably from
about 3:1 to about 1:3.
After all the ingredients are completely dissolved, the water-solvent
system is removed by processes well known to the art, such as vacuum
drying, distillation, flash or drum drying.
The plasticized mixture of chips from the drying step may then be placed
into a chip mixer where additional ingredients, normally found in toilet
bars but which were not added during preparation of the solution, are
blended to form a uniform mixture. The material is then formed into toilet
bars in accordance with well-known methods in the art, such as will be
found in U.S. Pat. Nos. 2,781,321 and 2,894,912.
TABLE 3
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Ingredients Plodding
Stamping
Sampel
A B C Lather
Charac-
Charac-
No. % % % Avg. Eval.
teristic
teristic
Remarks
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Mushy; wear
399 67 --
33 8-8-6 G F rate high
437 67 33
-- 4-5-4 F U
472 53 11
36 8-8-7 U E Bar cracked
*468 61 23
16 9-10-9
E E
*471 68 14
18 9-10-10
F G
473 35 11
54 8-7-7 U G Bar cracked
474 50 50
-- 1-1-1 U U
469 -- 23
77 8-8-6 G U Bar cracked
475 -- 11
89 8-6-4 E U Bar cracked
476 26 47
27 2-2-2 F U Sticky
477 -- 43
57 2-3-2 U U
478 100
--
-- 5-6-3 U U
479 91 4
5 7-8-9 E E
480 63/ 11
26
9-8-8
E E
*481 70 25
5 10-10-10
F E
*482 70 25
5 10-10-10
FE
*485 80 10
10 10-10-10
E E
*486 72 8
20 10-8-8
E F
*487 70 5
25 9-8-9 G E
*488 62 30
8 10-9-10
E E
*489 50 25
25 10-10-10
E E
*490 50 35
15
10-10-8
E E
442 -- --
100
8-1-5 G U Bar cracked
*470 35 29
36
8-8-7 E E
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*Bars having a composition delineated in FIG. 1
E = Excellent
G = Good
F = Fair
U = Unsatisfactory
EXAMPLE 1
63 lbs. of an equal mixture of C.sub.12 /C.sub.14 alkane sulfonates (85%
active, the balance consisting of Na.sub.2 SO.sub.4 and related inorganic
salts), 21 lbs. of partially hardened coconut oil fatty acid and 16 lbs.
of Igepon A (a commercial coconut oil fatty acid ester of sodium
isethionate) are homogeneously blended together and then admixed in a chip
mixer with 0.3 lb. titanium dioxide, 1.0 lb. of perfume and 7.5 lbs. of
water. This charge is then milled 3 times on a high speed 3-roll mill,
plodded into logs in a two-stage vacuum plodder, cut and stamped into
bars. (This example corresponds to the composition of point X of FIG. 1).
EXAMPLE 2
Example 1 is repeated except that the composition is changed to 75 lbs. of
an equal mixture of C.sub.12 alkane sulfonates, 18 lbs. partially hardened
coconut oil fatty acids, and 7 lbs. of a hydroxyalkylmethyl tauride formed
by reacting C.sub.14 -C.sub.16 epoxide with sodium N-methyl taurine.
EXAMPLE 3
Example 1 is repeated except that the composition is changed to 50 lbs. an
equal mixture of C.sub.10 /C.sub.14 alkane sulfonates (95% active), 25
lbs. (Ethyl Corporation's L-65) synthetic fatty acids consisting of 65%
C.sub.12, 28% C.sub.14 and 7% C.sub.16 essentially normal alkanoic acids,
and 25 lbs. Igepon T, coco N-methyl tauride.
EXAMPLE 4
80 lbs. of a 50/50 mixture of C.sub.10 /C.sub.14 alkane sulfonates (sodium
salts), (80% active, the balance consisting of Na.sub.2 SO.sub.4 and
related inorganic salts) are blended in a chip mixer with 25 lbs. of
partially hardened coconut oil fatty acids (sodium salts) and 25 lbs. of
Igepon A (a commercial coconut oil fatty acid ester of sodium
isethionate). To this charge is admixed 1.3 lbs. of perfume and 0.4 lbs.
titanium dioxide dispersed in 9 lbs. of water. The total mixture is then
milled 3 times on a high speed Day 3-roller mill. The material is then
refined, plodded into logs, cut and stamped into bars.
EXAMPLE 5
The sodium salt of an equal mixture of C.sub.10 /C.sub.14 alkane sulfonates
(95% active), 40 lbs., is dissolved in a mixture of 80 lbs. of anhydrous
isopropanol and 125 lbs. of deionized water at 150.degree. F. In this
mixture is dissolved 10 lbs. of partially hydrogenated coconut oil fatty
acids and 15 lbs. of sodium mono-C.sub.14 -alkyl maleate, and the pH of
this solution is adjusted to 6.0 by the addition of a small amount of a
50% aqueous solution of NaOH. The isopropanol is distilled off and the
remaining aqueous solution is drum dried. The resulting solid actives are
then blended in a chip mixer with 10 lbs. water, 0.2 lb. titanium
hydroxide and 0.75 lb. perfume. The chips are plodded into logs, cut to
size and finally stamped into bars, having a pH of approximately 6.9.
EXAMPLE 6
In place of the alkane sulfonate of Example 5, there is substituted 40 lbs.
of alkane sulfonate made from "cracked wax" .alpha.-olefins comprised
essentially of equal parts of C.sub.11, C.sub.12, C.sub.13 and C.sub.14
components.
EXAMPLE 7
In place of the 15 lbs. coconut oil fatty acids and 10 lbs. of Igepon A of
Example 5 are substituted 10 lbs. of partially hydrogenated coconut oil
fatty acids, 10 lbs. of Stepan's C.sub.14 -C.sub.18 alkane sulfonate and 5
lbs. of 80/20 (tallow/coco) soap chips.
EXAMPLE 8
In place of the 80 lbs. of a 50/50 mixture of C.sub.10 /C.sub.14 alkane
sulfonates of Example 4, there is substituted a 40/60 mixture.
EXAMPLE 9
In place of the 40/60 mixture of C.sub.10 /C.sub.14 alkane sulfonates of
Example 8, there is substituted a 60/40 mixture.
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