Translucent soap bar containing citronellyl esters as lime soap dispersants

A translucent deodorant non-germicidal soap bar incorporates selected citronellyl esters, and a suitable alcohol, especially those selected from polyalkylene glycols and/or liquid polyols, to make a soap composition that has superior lime soap dispersancy without loss of translucency, and, in at least one case, is both deodorant and non-germicidal. The polyols have a molecular weight between about 62 to about 342 and the polyalkylene glycols have a molecular weight between about 200 to about 4,000. An effective amount of citronellyl senecioate is added, preferably about 1% by weight. The preferred concentrations of the polyalkylene glycols and polyols range between about 0.5% to 5% by weight.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the art of making translucent soap bars and more 
particularly to improving the lime soap dispersancy of such bars, and 
adding a deodorant non-germicidal ingredient thereto without impairing the 
translucency. 
2. The Prior Art 
Soap making is an ancient art whose basic precepts are still employed in 
present day manufacturing plants. One of the ancient specialties of soap 
making is the art of compounding translucent and transparent bars which, 
for the purposes of this disclosure, may be lumped under the single 
category "translucent bars." Because of their attractive appearance, 
translucent bars command a limited but significant share of the market. 
The optimum qualities of a translucent bar soap in the prior art are 
taught in U.S. Pat. No. 3,864,272. 
But for the influence of certain problems hereafter discussed, translucent 
bars might have a significantly larger and more important share of the 
market. Among the problems of the prior art is the difficulty in making a 
translucent bar which performs well in hard water, and especially one that 
is deodorant and non-germicidal. 
In many parts of this country and other parts of the world, the water is 
"hard" by reason of the presence of bivalent ions such as, for example, 
magnesium and calcium, which combine with the fatty acids of soap to form 
an insoluble product known as "lime soap." A soap that performs well in 
hard water must have the ability to disperse and hold in solution this 
lime soap, which property will sometimes hereafter be referred to as lime 
soap dispersancy. 
The prior art workers succeeded in making a translucent soap bar which is 
deodorant and/or germicidal or a translucent bar which performs reasonably 
well in hard water, but they have not been able to make a deodorant, 
non-germicidal, translucent bar that performs well in hard water. 
Thus, in hard water areas, users have to forego either translucency or 
deodorancy because lime soap dispersancy in such areas is absolutely 
essential. Moreover, a need exists for an ordinary translucent bar with 
improved lime soap dispersancy. 
These problems represent an existing need felt by the user and the soap 
industry, and they have been met by means of the instant invention. 
3. Brief Summary of the Invention 
It has been discovered that the combination of a soap base, a citronellyl 
ester (such as, for example, citronellyl senecioate, citronellyl formate, 
citronellyl acetate and citronellyl isobuterate) and a suitable alcohol, 
especially one or more polyalkylene glycols having a molecular weight 
between about 200 and about 4,000, preferably those selected from the 
group consisting of polyethylene glycol having a molecular weight from 
about 600 to about 1500, and/or one or more polyhydric alcohols having a 
molecular weight between about 62 and about 342, preferably those selected 
from the group consisting of diols and triols having a molecular weight 
from about 76 to about 134, is a significantly better translucent soap 
having improved lime soap dispersancy; and in at least one instance 
(citronellyl senecioate) it adds deodorant activity to the soap bar 
without destroying its translucent character. 
A concentration of a citronellyl ester of at least about 1.0 weight percent 
is required for noticeably effective results--the upper limit being 
dictated by economics--for a translucent bar that exhibits deodorancy. 
Inasmuch as citronellyl senecioate has a demonstrated deodorancy (see U.S. 
Pat. No. 3,493,650 to Universal Oil Products), it may be inferred that the 
other citronellyl esters also have deodorancy. 
A range of concentration from about 0.5% to 5% of polyalkylene glycol 
and/or polyhydric alcohol is ideal for satisfactory results. Examples of 
polyols useful in this invention are, among others, butanediol, hexylene 
glycol, 1,5-pentanediol, cyclohexanediol, and sugars such as sucrose and 
sorbitol. Examples of polyalkylene glycols are polyoxypropylene glycol and 
polyoxybutylene glycol. As much as 30% by weight of a soap bar could be 
added, but much lower concentrations are preferred. 
A soap suitable for the translucent bar of this invention is a long chain 
fatty acid neutralized by a suitable alkali metal hydroxide, preferably 
sodium and/or potassium hydroxide. It is also preferable to use a slight 
excess of the alkali metal hydroxide in the neutralization step to improve 
soap stability. The fatty acids employed may be obtained from any typical 
fatty acid source that is consistent with the state of the art. The soap 
composition may also contain additional additives consistent with the 
state of the art such as silica and clarifying agents, emollients, 
perfumes, color, etc. 
Subject to the above remarks, a preferred translucent soap is one made 
according to the teachings of U.S. Pat. No. 3,864,272 to Toma, et al, in 
combination with a citronellyl ester, e.g., citronellyl formate, 
citronellyl acetate, citronellyl isobuterate, and citronellyl senecioate. 
As taught in the said patent, in some combinations containing only one of 
the glycols or polyols, the addition of glycerine, suitably from about 1-3 
percent based on the weight of the soap is necessary. 
PREFERRED EMBODIMENTS OF THE INVENTION 
The presently preferred embodiment of the invention comprises a translucent 
soap containing an 80/20 ratio of Tallow/Coco which contains a 94/6 Na/K 
ratio, 11/2% polyethylene glycol having a molecular weight of about one 
thousand (this can be obtained commercially under the trade name Carbowax 
from the Union Carbide Corp.), 11/2% propylene glycol having a molecular 
weight of 76, 1% citronellyl seneciotate (this can be obtained 
commercially from Naarden-UOP Fragrances, Inc. under the trademark 
"Sinodor"), and a water content relating to 18% (.+-.2%) soap pellet 
moisture. Compatible color and perfume are added q.s. to this soap 
composition. 
The inclusion of both a polyalkylene glycol and a polyol is preferred, 
although satisfactory results can be obtained with the inclusion of only 
one of the two. A suitable combination would be the soap base 
above-described with 3% polyethylene glycol having a molecular weight of 
1,000 and 1% citronellyl senecioate, to which may be added compatible 
perfumes and color, q.s. Similarly, propylene glycol may be substituted 
for the polyethylene glycol, thus yielding a satisfactory but less 
preferred product. 
Other liquid polyols having molecular weights between 62 and 342 may also 
be substituted for the preferred propylene glycol ingredient with 
satisfactory results. Examples of such polyol substitutes are glycerine, 
hexylene glycol, cyclohexanediol and sorbitol. The consideration involved 
in selecting polyols is that they be selected from those that do not 
destroy the translucent property of the bar. The polyol selection from the 
molecular weight range indicated satisfies this requirement. 
Polyalkylene glycols having molecular weights between 200 and 4,000 may 
also be substituted for the preferred ethylene glycol-1000 with 
satisfactory results. Examples of such polyalkylene glycols are 
polyoxypropylene glycol and polyoxbutylene glycol. The important 
consideration involved in selecting a polyalkylene glycol are that it be 
completely miscible with the citronellyl compound and that it not destroy 
the translucent property of the product. 
To the soap product of this invention may be added perfumes and colors q.s. 
Not all perfumes and not all colors will work in a translucent soap bar; 
however, the usable colors and perfumes are well-known to persons working 
in the art, and a suitable selection can be made without undue 
experimentation. An example of a soap bar with color and perfume is shown 
in Example III hereafter.

EXAMPLE I 
A study of lime soap dispersancy was conducted on translucent soap 
containing 0.4%, 1% and simulated 5 and 10% citronellyl senecioate in 
combination with polyethylene glycol having a molecular weight of about 
one thousand and propylene glycol according to the following protocol: 
Ten percent soap solutions containing an 80/20 ratio of Tallow/coco and 
94/6 ratio of Na/K, and 0.4%, 1%, 5% and 10% citronellyl senecioate, were 
prepared by dissolving the soap in deionized water. Finished soap bars 
were used to make the 0.4% and 1% citronellyl senecioate soap solutions. 
Because of the unavailability of finished bars, the 5% and 10% citronellyl 
senecioate solutions were simulated by making the soap solutions with 
placebo and adding the citronellyl senecioate directly to the solutions. 
To 100 gram samples of hard water containing 200, 300, 350, 400, 500 and 
600 ppm of calcium carbonate respectively were added 1 ml. aliquots of the 
10% solutions. The resulting series of 0.1% soap solutions in hard water 
were graded for visible dispersed lime soap and flocculated lime soap on 
the following scale. 
Curd Appearance 
D=Dispersed lime soap only. 
DF=Dispersed lime soap with trace amount of flocculent precipitate. 
MF=Moderate amount of flocculent precipitate. 
F=Large amount of flocculent precipitate. 
Solution Appearance 
0=No visible dispersed lime soap. 
1=Trace amount of visible dispersed lime soap--light haze 
2=Moderate amount of visible dispersed lime soap--transparent. 
3=Large amount of visible dispersed lime soap --thinly opaque. 
4=Very large amount of visible dispersed lime soap--milky opaque. 
The results, which showed that 1% Sinodor perceptibly improved lime soap 
dispersancy effect in this particular soap base, were recorded and 
reproduced below in Table I. 
TABLE I 
______________________________________ 
Lime Soap Dispersancy of Translucent Soaps 
Containing 0-10% Citronellyl Senecioate 
% Citronellyl Water Hardness (ppm-CaCO.sub.3) 
Senecioate in Bar 
200 300 350 400 500 600 
______________________________________ 
0-Placebo D3 D4 MF3 F2 F1 F1 
0.4 D3 D4 DF3 F2 F1 F1 
1 D3 D4 D4 F2 F1 F1 
5 D1 D2 -- DF4 F2 F1.5 
10 D1 D2 -- D4 DF4 MF4 
______________________________________ 
Water Hardness at Which Flocculent Precipitate 
First Appears for Translucent Soaps 
Containing 0-10% Citronellyl Senecioate 
% Citronellyl Senecioate in Bar 
Water Hardness (ppm-CaCO.sub.3) 
______________________________________ 
0-Placebo 300-350 
0.4 350 
1 350-400 
5 400 
10 500 
______________________________________ 
LIME SOAP SOLUBILITY AND DISPERSANT TEST 
A test method was developed for the purpose of determining the ability of 
additive candidates to dissolve and/or suspend lime soaps (calcium 
stearate, calcium palmitate, and magnesium stearate) when added to 
solutions of the additive with/without the presence of soap. This test 
method calls for addition of 0.02 g of each lime soap, individually or in 
combination, to 100 ml. of the additive test solution followed by a 
one-hour heating period of 50.degree. C. The test samples are then left at 
ambient temperatures for about 16 hours before final evaluation. Each 
sample is then evaluated according to opacity (o, finely divided suspended 
solids) and solids content (s, undissolved larger particles). A similar 
set of test samples containing only the appropriate lime soap(s) and 
deionized water was employed as the standard for this evaluation. Two 
scales were used for the evaluation: opacity (0 to -5) with 0=clear and 
-532 very heavy opacity, and solids (0 to +5) with 0=same amount as 
standard and +5=no large particulate matter. All solutions were made with 
deionized water. The soap used was the 85/15 (T/C) and 94/6 ratio of Na/K. 
The set of scores for each additive was then compared to those found for 
soap (3.4.times.10.sup.-4 M). The values were tabulated and recorded in 
Table II below. In the convention adopted the more positive value in each 
column of the Table indicates the better performance. Thereafter, the 
column differences (.+-. depending on the performance relative to soap) 
were then totaled to give a composite dispersing score. 
TABLE II 
______________________________________ 
Ca Ca Mg All 
Palmitate 
Stearate Stearate Three 
o s o s o s o s 
______________________________________ 
Soap = -1 +3 -4 +3 -4 +1 -5 +2 
Citronellyl 
Senecioate 
+ Soap = -1 +3 -31/2 
+2 -3 +2 -5 +21/2 
Difference = 
0 0 +1/2 -1 +1 +1 0 +1/2 
Difference 
Total = +2 
______________________________________ 
EXAMPLE II 
Using the protocol of Example I, various combinations of soap, citronellyl 
senecioate, polyethylene glycol and propylene glycol were tested for lime 
soap dispersancy, using a base score of zero for soap only having an 85/15 
Tallow/coco ratio. The full combination was made according to the 
following formula: Soap 3.4.times.10.sup.-4 M; 5.times.10.sup.-4 M 
polyethylene glycol 1000; 66.times.10.sup.31 4 M propylene glycol, and 
3.4.times.10.sup.-4 M citronellyl senecioate. Various combinations of 
ingredients were obtained by deleting one or more ingredients. The results 
are shown in Table III below. 
TABLE III 
______________________________________ 
Active Score 
______________________________________ 
Soap 0 
Soap + Citronellyl Senecioate 
+2 
Soap + Polyethylene Glycol 1000 (PEG) 
+3.5 
Soap + Propylene Glycol (P.G.) 
+3.5 
Soap + P.G. + Citronellyl Senecioate 
+5 
Soap + PEG + Citronellyl Senecioate 
+8.5 
______________________________________ 
The concentration of citronellyl senecioate may be from about 1% to about 
10% by weight. The limiting factor on the upper range of the concentration 
is principally economic inasmuch as the testing done with various 
concentrations of citronellyl senecioate makes it appear that the lime 
soap dispersancy effect is proportional to the amount of citronellyl 
present. The amount included should be enough to be effective which may 
vary according to the formulation. 
The ratio of citronellyl senecioate to polyol and/or polyalkylene glycol is 
not critical; however, the preferred ratio is about 20:1 to 1:5. 
EXAMPLE III 
A translucent soap bar was made according to the following formula: Soap 
80/20 (T/C) with 94/6 (Na/K) ratio, 77.56%; polyethylene glycol 1000, 
11/2%; propylene glycol, 11/2%; lemon perfume 0.4%; color 0.04%; water 
(18% pellet moisture); citronellyl senecioate 1%. 
The mechanism of the invention seems to proceed in two ways: one by delayed 
flock reaction and a second by increased dispersion of lime soap. Because 
the two mechanisms seem to play a presently uncharted role in the 
reactions, the optimum mix of polyalkylene glycols may vary depending on 
the concentrations and identities of the citronellyls and polyols. 
However, with the teachings of this disclosure as a reference, a person 
ordinarily skilled in the art can practice the invention without need for 
undue experimentation. The examples that follow will help in this respect. 
EXAMPLE IV 
Four compounds: citronellyl senecioate, citronellyl acetate, citronellyl 
formate, and citronellyl isobuterate were tested according to the protocol 
described in Example I above. The results indicated that citronellyl 
formate and citronellyl isobuterate are as effective with respect to lime 
soap dispersion as citronellyl senecioate in combination with carbowax 
1000 and propylene glycol. Citronellyl acetate also shows significant lime 
soap dispersal activity. 
The test results are shown in Table IV below. 
TABLE IV 
______________________________________ 
Lime Soap Dispersion Action of Citronellyl Esters 
10% Active* 
Active 2 Min. 1 Hr. 
______________________________________ 
Carbowax 1000 + Propylene 
0/075*** 0/0 
Glycol**(C-P) 
C-P plus Sinodor**** 
170/&gt;150 125/100 
C-P plus Citronellyl Acetate 
100/&gt;200 0/100 
C-P plus Citronellyl Formate 
&gt;300/&gt;200 100/&gt;300 
C-P plus Citronellyl i-Buterate 
100/&gt;200 100/&gt;300 
______________________________________ 
*This % value represents the amount of lime soap dispersant relative to 
the amount of soap plus Carbowax 1000 + Propylene Glycol. 
**This value is an average of four test evaluations. The test 
concentrations were: Carbowax 1000 = 0.0015%, propylene glycol = 0.0015%, 
and soap = 0.097%. 
***The values shown are: (ppm CaCO.sub.3 at which fine flock appears for 
test soap) minus (ppm CaCO.sub.3 at which fine flock appears for placebo 
soap) / (ppm CaCo.sub.3 at which heavy flock appears for test soap) minus 
(ppm CaCO.sub.3 at which heavy flock appears for placebo soap). Thus, the 
higher scores indicate better lime soap dispersancy performances. 
****This result is an average of four test evaluations. 
EXAMPLE V 
Following the protocol described in Example I above, a number of tests of 
samples not containing a citronellyl were made to determine the lime soap 
dispersancy values of the combinations. The results are arranged below in 
order of decreasing efficacy. 
TABLE V 
Two Minute Evaluations 
1.5% PrG 
3% PEG+3% PrG 
3% PrG=3% PEG 
1.5% PEG+1.5% PrG=soap only 
1% PEG+1% PrG=5% PEG+5% PrG=5% PEG=2% PEG+3% PrG=3% PEG+2% PrG 
5% PrG 
All of the remaining combinations were equal to the 1.5% PEG plus 1.5% PrG 
combination. The main differences were in the amount of flock formation. 
TABLE IV 
One Hour Evaluations 
1.5% PrG=3% PEG=1% PEG+1% PrG=5% PEG+5% PrG=3% PEG+2% PrG 
1.5% PEG+1.5% PrG=soap only 
3% PEG+3% PrG 
The differences in these evaluations were slight, and were mainly exhibited 
in the dispersion power at water hardness equal to 300 ppm CaCO.sub.3. All 
of the remaining combinations were equal to the 1.5% PEG plus 1.5% PrG 
combination. 
EXAMPLE VI 
Following the protocol of Example I above, combinations of propylene glycol 
and Carbowax (polyethylene glycol, molecular weight 1000) were tested in 
the presence of a soap solution containing ten percent citronellyl 
senecioate (soap plus polyalkylene glycol and citronellyl senecioate 
equalling 100%). The addition of the citronellyl senecioate improved the 
lime soap dispersancy performance in every example tested, resulting in an 
improvement in decreased and delayed flock formation characteristics of 
water hardnesses, especially those below 400 parts per million CaCO.sub.3. 
The results at two minute evaluations were better than corresponding 
results obtained from one hour evaluations. The results are listed below 
in Tables VII and VIII in order of decreasing efficacy. 
TABLE VII 
Two Minute Evaluations 
1.5% PrG 
3.0% PrG=3% PEG=3% PrG=0.5% PEG=0.5% PrG 
1.5% PEG+1.5% PrG=3% PEG=3% PEG -2% Prg 
TABLE VIII 
One Hour Evaluations 
0.5% PEG 
3% PEG 
3% PrG 
1.5% PEG+1.5% PrG 
2% PEG+3% PrG 
3% PEG+2% PrG=5% PrG=5% PEG+5% PrG 
0.1% PEG+0.1% PrG 
5% PEG