Field of the invention
The present invention relates to an improved transparent soap bar more specifically the
present invention discloses a bathing bar which gives high transparency and foaming property
with reduction in the rate of wear.
Background and Prior art of the Invention
Transparent soaps are made based on the sodium salts of fatty acids such as Lauric, palmitic
and stearic acids as the major soap ingredient. Together the formulation meeting bathing bar
specifications have synthetic surfactants such as Sodium lauryl sulfate, Sodium cumene
sulphonate, Coco-amidopropyl betaine and Sodium lauryl ether sulphate. Proper solvent
combinations of mono- and polyhydric alcohols such as isopropanol, sorbitol, propylene
glycol, polyethylene glycol and water impart the required transparency. One of the key
features of this soap composition is its high rate of wear. This also means that the soap lasts
for less number of washes as compared to an opaque soap. Hence the rate of wear of the soap
has a correlation to the perceived consumer value. Too low a rate of wear results in less soap
being dispensed during use and this in turn results in less foam which is also not desirable.
Thus the rate of wear is determined by the formulation. While one approach to reduce the
rate of wear is to increase the ratio of the insoluble soaps, it has undesired effects such as loss
of transparency, reduction in foaming properties and extensive structuring of the bar.
It is well known that myristic acid increases structuring in the soap composition especially in
the sodium based soap. It also offers good cleansing properties and produces nice fluffy and
creamy lather. Sodium myristate is water soluble and used in liquid soap without reducing
transparency of the product. Due to its cleansing abilities, too much myristic acid based soap
produces somewhat of a drying product. Myristic acid is a saturated and linear fatty acid
which has a chain length of 14 carbons. Significant percentages of myristic acid are found in
the oil of palm kernels.
Transparent soap bars are normally perceived to be milder than opaque bars. These soaps, for
their distinctive appearance, depend upon the fact that soap is formed from alcoholic solution
in a transparent, ultra microcrystalline form. If formed from a non-alcoholic base, then it is
cooled at a particular rate to provide the same effect. In general transparent soaps melt faster
than the opaque bars.
US5529714 discloses a formulation for transparent soap and methods of preparing the same.
The transparent soaps are prepared by combining high and low molecular weight fatty acids
in the presence of polyhydric alcohols. Citric acid is added to adjust pH. The formulations do
not require volatile; short-chain monohydric alcohols to achieve transparency and the end
products are able to retain transparent qualities when exposed to hot water conditions.
Suitable formulation is remelted to reduce waste.
US5993371 discloses a transparent soap bars having improved lathering and foaming
characteristics contain (1) an alkanolamine; (2) an alkyl polyglycoside of the formula I

wherein R1 is a monovalent organic radical having from about 6 to about 30 carbon atoms; R2
is divalent alkylene radical having from 2 to 4 carbon atoms; Z is a saccharide residue having
5 or 6 carbon atoms; b is a number having a value from 0 to about 12; a is a number having a
value from 1 to about 6: (3) a polyol; (4) a fatty acid which is at least 70% neutralized by
sodium hydroxide,- and; (5) water wherein the water to free alkanolamine weight ratio is
greater than 1.0 and the ratio of the weight of the polyol to the sum of the weights of free
alkanolamine, alkyl polyglycoside, polyol and water is less than about 0.4.
WO 88/09805 discloses a transparent soap composition comprising 10 to 40 % by weight of
a sucrose fatty acid ester containing at least 50 % by weight of sucrose monolaurate, 15 to 60
% by weight of sodium salts of saturated fatty acids comprising sodium salts of each of
palmitic, stearic and myristic acids (purity of each fatty acid: at least 95 %), and a clarifier,
wherein the content of myristic acid is 50 % by weight or less based on the total weight of the
constituent fatty acids of the sodium salts of saturated fatty acids. The soap prepared from
this composition exhibits not only very low pungency but also excellent foaming property
and transparency.
JP1054100 discloses a soap composition comprising 10-40 wt % sucrose fatty acid ester.
Sucrose monolaurate in an amount of 50wt.% or above, 15-60 wt % saturated fatty acid
sodium salt consisting of a sodium salt of each of palmitic acid, stearic acid and myristic acid
(each having a purity of 95% or above), and a clarifier. The amount of myristic acid is 50 wt
% or less based on the total wt. of the constituent fatty acids of the satd. fatty acid sodium
salt.
US6,656,893 discloses a transparent bar soap composition comprising a sodium salt of a fatty
acid or a mixed sodium/potassium salt of a fatty acid, at least one amphoteric surfactant
selected from the group consisting of compounds represented by formulas (A) to (C), a
nonionic surfactant, and at least one glycerine derivative. The sodium salt of a fatty acid
include sodium laurate, sodium myristate, sodium palmitate, sodium stearate, sodium oleate,
sodium isostearate, sodium tallowate, sodium cocoate, sodium palm kemelate, etc. Due to the
presence of amphoteric surfactant and the fatty acid (i.e. the sodium salt of a fatty acid, or the
mixed sodium/potassium salt of a fatty acid) form a complex salt. As a result, the transparent
bar soap composition of the present invention is improved in transparency and hardness. At
the same time, the increased hardness of the soap results in reduction of the wear rate.
US6297205 discloses the art of making transparent soaps when the fatty acids are from 3-
20% however it does not mention method to obtain transparency when the fatty acids in the
composition are higher than 20%. Regulatory requirements impose a minimum of 40TFM in
soaps hence it is imperative that the transparent soap should have the fatty acid composition
above 30%. Thus it is a continuing challenge to provide a formulation with high levels of
fatty acid salts with transparency and desirable rate of wear.
Transparent soaps made by the conventional melt and pour method employing around 20-
40% of sodium salts of fatty acids, around 7-10% synthetic surfactants, around 30-40%
solvents and 5-10%) of additives such as salt, preservatives, perfume, extracts, etc generally
exhibit significantly higher rate of wear in comparison to opaque soaps. In the transparent
soap of such prior art the rate of wear is usually high and the soap cannot be used for more
number of washes. On the other hand the transparent soaps which provide less rate of wear
property mostly lack adequate transparency.
Thus there is need to provide lower rate of wear along with high transparency over the prior
art soaps.
Objects of the invention
One of the objects of the present invention is to provide a transparent soap which has low
wear rate in nature.
Another object of the present invention is to provide a transparent soap with high
transparency.
A further object of the present invention is to provide a transparent soap which gives high
foaming property.
A further object of the present invention is to provide a process for preparation of transparent
soap which gives high foaming property.
Summary of the Invention
A transparent soap composition with desired rate of wear property, comprising a crystal
inhibitor; Myristic acid/salts thereof; surfactant selected from soap-based surfactant; anionic
surfactant and amphoteric surfactant and mixtures thereof.
A process for preparation of a transparent soap bar with desired rate of wear property,
comprising the steps of melting of the fat phase in a suitable Mixing Vessel, followed by
saponification and fatty acid neutralization using aqueous alkali to generate soap-based
surfactants in-situ, to which are subsequently added the crystal inhibitor and the remaining
surfactants while continuously agitating the mixture.
Detailed Description of the Invention
The present inventors have surprisingly found transparent soap formulation wherein
reduction in rate of wear properties of the soap formulation is accomplished by employing the
synergy between the crystal inhibitor like Sucrose/its derivatives and Myristic acid/salts
thereof The formulation has excellent transparency and foaming properties with low rate of
wear. The myristic acid/ salts thereof and sucrose when used alone in the formulations do not
give the desired properties however when provides in defined amounts they act
synergistically to achieve the desired properties.
(a) Method for inspecting transparency: Transparency is described with respect to two
aspects, viz., (i) Visual inspection for haziness and (ii) Percentage transmittance at 700nm
when measured as a 1 cm thick slab.
(i)Visual inspection for presence or absence of haziness: On visual inspection of the
sample of the dimension 5 cm x 5 cm x 2cm when held against a florescent light
source. The results and observation are tabulated as given below.

(ii) Percentage transmission: Prepare a rectangular sample of 1 cm uniform thickness
using a sharp blade. The percentage transmittance at 700nm is measured with a UV-
Visible spectrophotometer.

(b) Method of Rate of Wear: Weigh ~120g soap tablet accurately using an analytical
balance. Hold the soap in one palm and rotate it 100 times under running water (soft
water). After this procedure dry the soap. Repeat the same procedure every day for 5
consecutive days. Weigh the dry tablet at the end of the process.
Rate of wear = {(initial weight-Final weight)/Initial weight}*100.
For soaps meeting the criteria of high transparency and clear as defined in (a) above, the
rate of wear is classified as given below.

(c) Method for Measurement of Lather Volume @ 24 FH using Mixie Method:
Take 100 ml of 240 ppm hard water (at 27 degree centigrade) along with 5g of grated sample
to the water in the blending jar, covered the blender on low speed for about 60 s. Pour the
Lather quickly into the cylinder and measure the lather volume immediately after levelling of
top surface of the foam. Repeat the experiment for three trials to get an average.
(d) Measurement for Foam Height @ 30FH using Ross-Miles Column:
Dissolve 5 g of the grated soap in 30 FH hard water. Make up the soap solution using 30 FH
hard water to 500 mL in a standard measuring flask. Rinse the walls of the Ross-Miles
column with 50 ml of the solution using a pipette; adjust the stopcock so that the level of
height solution in the receiver is exactly at the 50 ml mark. Fill the pipette with the solution
to the 200 ml mark using a slight suction for the purpose. Immediately place it in position at
the top of the receiver and opened the stopcock. When all of the solution has run out of the
pipette, measure the level of foam production at the top of the foam column at the highest
average height to which the rim of the foam to the volume of air remaining in the foam.
Repeat the experiment for three trials to get an average.
The attributes of the transparent soap formulation of the present invention is characterized by
reference to several categories such as transparency, haziness, foaming and wear rate. The
improved transparent soap composition includes more than one or more components: a
crystal inhibitor like sucrose; a sodium myristate; a soap-based surfactant; multiple anionic
surfactant and amphoteric surfactant or mixture thereof.
Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier
spreading, and lowering of the interfacial tension between two liquids. Surfactant is classified
by the presence of formally charged groups in its head. A non-ionic surfactant has no charge
groups in its head. The head of an ionic surfactant carries a net charge. If the charge is
negative, the surfactant is more specifically called anionic; while the charge is positive, it is
called cationic.
An anionic surfactant has an anionic hydrophilic group. Examples of anionic surfactants are
generally called "soap" (fatty acid soap), alkylsulfonic acid salts (the main component of
synthetic detergent, such as linear alkyl benzene sulfonate (LAS)), fatty alcohol sulfate (the
main component of shampoo or old neutral detergents), etc. Because fatty acid soap is a salt
of fatty acid and alkali metal (a salt of a weak acid and a strong base), it hydrolyzes in water
and the solution becomes slightly basic. However, the solutions of other anionic surfactants
are neutral. The solution of synthetic detergent is adjusted to slightly basic, but this is not
because of the detergent itself (it is neutral) but because of the effect of auxiliary agents
(sodium carbonate, etc).
Myristic acid, also called tetradecanoic acid or 14:0 is a common saturated fatty acid with the
molecular formula CH3(CH2)12COOH. A myristate is a salt or ester of myristic acid.
The composition of the present invention comprises sodium myristate in amount of 1 to 5%
by weight.
Crystal inhibitor used herein is sucrose or its derivatives, preferably sucrose in the amount of
8 to 15%% by weight.
Sucrose, commonly known as table sugar, is by far the most abundant carbohydrate found in
the sap of land plants. It is one of the few nonreducing sugars available in a state of
unexcelled purity, in highly crystalline form, on a very large scale, and at low cost. It has
been produced since 2000 B.C. from the juice of the sugar cane and since the early 1800's
from the sugar beet. Sucrose is a sweet, crystalline (monoclinic) solid which melts at 160°-
186° C, depending on the solvent of crystallization. Sucrose is highly desirable from the
standpoint of skin mildness and lathering and process ability. Sucrose has an unexpectedly
dramatic thinning effect on the soap mix which eliminates the need to add excess water or
solvent for homogeneous mixing. Sucrose helps to reduce the viscosity profile of soap and
aids in maintaining isotropicity of the liquid soap melt.
The surfactant are selected from soap based surfactant, anionic surfactant, amphoteric
surfactant and mixtures thereof.
The soap based surfactant selected from sodium salts of fatty acid, examples Capric acid,
lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic
acid. Percentage by weight of soap based surfactant present in the present composition is in
the range of 21 to 50% by weight.
The anionic surfactant is selected from sodium lauryl sulfate, sodium lauryl ether sulfate
(IEO), sodium lauryl ether sulfate (2EO), sodium cumene sulfonate and sodium xylene
sulfonate. The anionic surfactant is present in the amount of 5 to 15% in the present soap
composition.
The amphoteric surfactants are selected from cocamidopropylbetaine, cocoamido betaine,
and amineoxides in the amount of 0.2 to 1.9% by weight.
Conventional ingredients selected from humectants, antibacterial, anti-oxidant, preservatives,
fragrance, electrolyte, extracts, colors and diluents. Some of the conventional ingredients
used are triclosan, trichlocarbanilide, sodium chloride, sodium metabisulfite, EHDP,
tetrasodium EDTA, BHT, extracts of seaweed, FP Green 635 color, etc.
The preferred formulations for the present transparent soap contain the ingredients and ranges
outlined in the Table 1. All the values are expressed in weight percents.
Components crystal inhibitor; sodium myristate; surfactant selected from soap-based
surfactant; anionic surfactant and amphoteric surfactant and mixtures thereof are mixed and
fonnulated into soap bar along with conventional ingredients. The process of preparing a
transparent soap bar involves melting of the fat phase in a suitable Mixing Vessel, followed
by saponification and fatty acid neutralization using aqueous alkali to generate soap-based
surfactants in-situ, to which are subsequently added the crystal inhibitor and the remaining
surfactants while continuously agitating the mixture.
The present invention is illustrated by the following non-limiting examples. It is to be
understood that the disclosed methodology is not limited to the exact details briefed here and
variations to implement the idea are possible. The methodology described is for the purpose
of description and should not be taken as limitation.
The examples 1 and 2 can be quoted as prior art.
Examples 1 and 2
In the below the ingredients of Standard soap formulation is shown in tabular form in table 2.
The standard soap composition contains Sorbitol (no sucrose) and does not contain sodium
myristate.
According to Table 2 (Example 1 and Example 2) when hystric and lauric acids are used in
equal concentrations and sorbitol used as solvent, the soaps obtained are transparent and
clear. However in absence of myristic acid the rate of wear is high and is not a desirable soap
composition.
Examples 3 and 4
The ingredients of Sucrose based soap formulation is shown in table 3 along with their
specific amount in each Example. The soap compositions contain sucrose (no sorbitol) as
base solvent and without sodium myristate.
As shown in the above table the ingredients are almost same as table 2 only the difference is
the Examples in table 3 is done with sucrose as a solvent in place of sorbitol. Example 3 and
4 of above table show that hystric and lauric acid are used in equal concentrations, the soap
obtained are transparent. However in absence of the myristic acid the-rate of wear is high
(similar to the Examples 1 and 2 in table 2) and is not a desirable consumer property.
Examples 5 to 11
The main ingredients of sodium myristate-sorbitol based soap composition are shown in
Examples 5 to 11 in table 4 below. The soap compositions contain sorbitol (no sucrose) as
base solvent and also sodium myristate.
According to above table 4 the results of Examples 5 to 11 indicate that the introduction of
sodium myristate at the cost of sodium laurate into the formulation affects the transparency of
the soap tables for Example 5-8, however it has no effect on transparency of Examples 9-11
for which it is high transparency. However, the visual inspection for all the samples show
that they are hazy. With respect to rate of wear, it is very low for Example 5, moderate for 6
and 10 and high for the rest of the Examples. Thus for the Examples 5-11 it is clear that
when only sodium myristate is present in the absence of sucrose all the three requirements of
high transparency, no haziness and low rate of wear property are not achieved together.
Examples 12 to 16
In the table-5 below the soap compositions containing sucrose (no sorbitol) as base solvent
and also sodium myristate are shown.
In the examples shown in Table 5, all the formulations contain sodium myristate at levels
above 5%. These soaps from the examples have low rate of wear property, however, all the
samples display haziness on visual inspection and hence not acceptable. Also, while it is not
the highlight of this invention, lathering of the soap formulation is a key consumer attribute.
With higher levels of sodium myristate (>5%) in the presence of sucrose, there is a significant
decrease of the lather volume (<525 mL that is the minimum consumer acceptable for
transparent soaps of this type).
Examples 17 to 22
The soap compositions containing sucrose (no sorbitol) as base solvent and also sodium
myristate in lesser amount is shown in table-6 with respect to table-5.
In the table-5 and-6 sucrose is used as solvent and in the Examples 1 to 22. In Table 6,
Example 22, sodium myristate is used at very low levels at 0.5%. Here while the
transparency is high and there is no haziness, the rate of wear property is high and hence not
acceptable. Examples 17-21, in their formulations contain sodium myristate in the level 1.5
to 4%. All the example soap bars have high transparency, are clear (no haziness) and have
desirable low rate of wear property. As the percentage of sodium myristate increases the rate
of wear property lowers, yet remains in the acceptable range. All the formulations here in
Table 6, with lower levels of sodium myristate have consumer acceptable lather volume
(>525 mL).
The combinations involving sodium myristate above 5% (Example 1 to 16 ; table 2 to 5)
result in loss of transparency but less rate of wear and hence not a viable option.
While the combinations with sodium myristate much below 5% give transparent soaps but do
not provide the desired rate of wear (Example 20 to 22; table 6). The ideal range of 1 -%
(Example 17 to 19; table 6) of sodium myristate in combination with sucrose provides both
transparency and no haziness and improves the rate of wear characteristics (lowers) as well as
appropriate lather. These combinations provide the desired rate of wear of <45%.
We Claim:
1. A transparent soap composition with appropriate rate of wear property, comprising a
crystal inhibitor; myristic acid /salts thereof and surfactants selected from soap-based
surfactant, anionic surfactant and amphoteric surfactant and mixtures thereof.
2. The transparent soap composition as claimed in claim 1 wherein said crystal inhibitor
is selected from sucrose and its derivatives.
3. The transparent soap composition as claimed in claim 1 wherein said salt of myristic
acid is sodium myristate
4. The transparent soap composition as claimed in claim 3 wherein said sodium
myristate is present in amount of 1 to 5% by weight.
5. The transparent soap composition as claimed in claim 1 wherein said anionic
surfactant is selected from sodium lauryl sulfate, sodium lauryl ether sulfate lEO,
sodium cumene sulfonate, sodium lauryl ether sulfate 2E0 and sodium xylene
sulphonate.
6. The transparent soap composition as claimed in claim 5 wherein said anionic
surfactant is present in amount of 5 to 15% by weight.
7. The transparent soap composition as claimed in claim 1 wherein said crystal inhibitor
is present in amount of 8 to 15 % by weight.
8. The transparent soap composition as claimed in claim 1 wherein amphoteric
surfactant is selected from cocamidopropylbetaine, cocoamidobetaine and amine
oxide.
9. The transparent soap composition as claimed in claim 8 wherein amphoteric
surfactant is present in amount of 0.2 to 1.9% by weight.
10. The transparent soap composition as claimed in claim 1 wherein soap-based
surfactant is selected from sodium salts of fatty acid, (capric, lauric, myristic,
palmitic, stearic, oleic , linoleic and linolenic) and 21-50 % by weight.
11.The transparent soap composition as claimed in claim 10 wherein said soap-based
surfactant is present in amount of 35 to 45% by weight.
12. A process for preparation of a transparent soap composition with desired rate of wear
property, comprising the steps of melting of the fat phase in a suitable Mixing
Vessel, followed by saponification and fatty acid neutralization using aqueous alkali
to generate soap-based surfactants in-situ, to which are subsequently added the
crystal inhibitor and the remaining surfactants while continuously agitating the
mixture.
13. A transparent soap composition with appropriate rate of wear, transparency, and
lather as described herein with reference of examples.

A transparent soap composition with appropriate rate of wear property, comprising a crystal
inhibitor, sodium myristate and surfactants selected from soap-based surfactant; anionic
surfactant and amphoteric surfactant and mixtures thereof. A process for preparation of a
transparent soap composition with desired rate of wear property, comprising the steps of
melting of the fat phase in a suitable Mixing Vessel, followed by saponification and fatty acid
neutralization using aqueous alkali to generate soap-based surfactants in-situ, to which are
subsequently added the crystal inhibitor and the remaining surfactants while continuously
agitating the mixture.