[0001] The present invention relates generally to a method of making a transparent solid
soap and, more particularly, to a transparent solid soap which can be easily produced
without requiring a fine control of water content and a maturing period till reduction
in weight is settled and, besides, exhibits high stabilities of transparency and weight
with passage of time.
[0002] A transparent soap is visually beautiful and excellent in terms of safety and detergency,
and is therefore widely used as a detergent. Generally, the transparent soap is mixed
with a moisture-absorbing component as an indispensable component such as polysaccharide,
and the like in order to create the transparency and mixed, in addition, with a volatile
component such as ethanol, and the like.
[0003] The transparent solid soap, however, declines in terms of transparency when the moisture-absorbing
component absorbs the moisture content, and it is therefore required that fine control
of the water content be precisely made by a hot roll while monitoring the transparency
and the water content. Further, when mixed with a volatile component, the volatile
component volatilizes, resulting in a decrease in weight. Hence, a maturing period
as long as several weeks to several months is needed till the decrease in weight is
settled. Namely, it is quite troublesome to execute the control so as to exhibit high
transparency and high stabilities of transparency and of weight with passage of time
in terms of manufacturing the transparent solid soap.
[0004] Moreover, if processed as a soap with a stripe pattern by use of a conventional transparent
soap material together with other opaque soap materials, the transparency of the transparent
soap portion is spoiled by the moisture content contained in the opaque soap, which
leads to a drawback in which the stripe pattern becomes blurred. Furthermore, some
of the currently used transparent solid soaps are mixed with sorbitol defined as polysaccharide
in order to enhance the transparency. Sorbitol is, however, crystal-deposited as time
elapses enough to make the transparent soap cloudy, and it happens often that the
stability of transparency with the passage of time might be spoiled.
[0005] EP-A-0 335 026 discloses a transparent soap bar which requires the components to
fit within three critical ratios, and which comprises a mixture of alkanolammonium
and alkali metal C
12-C
22 atom fatty acid salts, and a solvent system.
[0006] Under such circumstances, there has been demanded a transparent soap that can be
easily produced without requiring fine control of the water content and a maturing
period and, besides, exhibits high stabilities of transparency and of weight with
the passage of time.
[0007] On the other hand, it has already been practiced that a transparent solid soap is
mixed with an organic amine such as triethanolamine, but high-concentration mixing
has not been carried out. Further it was not known that a transparent solid soap which
can be easily produced and exhibit high stability are obtained by mixing with organic
amine such as triethanolamine at a high concentration
[0008] The present inventors have obtained a soap that remains transparent even when polysaccharide
and alcohol are not present which involves including sodium hydroxide and an organic
amine in a predetermined ratio as the alkali for saponification and specifying the
quantity of alkali as a predetermined saponifying equivalent of the fatty acid, and
have found that this transparent soap is easy to produce and exhibits good stability.
[0009] Thus, according to the invention we provide a method of making a transparent solid
soap by saponifying fatty acid or animal/vegetable oil with alkali in the absence
of alcohol, which comprises mainly a salt of fatty acid, wherein
(1) said alkali is sodium hydroxide and organic amine, and the molar ratio of said
sodium hydroxide to said organic amine is from 1:0.8 to 1:1.8, and
(2) the quantity of said alkali is 2.2 to 2.7 saponifying equivalents of said fatty
acid or said animal/vegetable oil,
so as to obtain a transparent soap material, and pouring said material into a mold
and solidifying it by cooling.
[0010] It is particularly preferable that the organic amine is triethanolamine.
[0011] Note that the term "transparent" implies a state of being substantially clear with
slight turbidity as well as implying that transmissivity of visible light is approximately
25% or above. Moreover, the term "transparent" is not limited to achromatic transparency.
[0012] The term "saponifying equivalent" means the minimum alkali quantity needed for transforming
all of the fatty acid or animal/vegetable oil into a salt of the tatty acid, i.e.,
into a soap, and the quantity thereof should be regarded as 1 saponifying equivalent.
[0013] The transparent solid soap obtained by the method of the present invention does not
contain a polysaccharide such as sorbitol or alcohol such as ethanol as indispensable
components. Accordingly, the soap rarely becomes turbid as a result of moisture absorption
or crystal deposition, and the like, which happen with a soap comprising polysaccharide,
and is excellent in terms of stability of transparency over the passage of time. Moreover,
the transparent solid soap prepared according to the present invention is easy to
produce for the reason that the labor for controlling moisture content is reduced
because of the absence of moisture-absorbing components such as polysaccharide, and
that a maturing period until the content of a volatile component such as alcohol has
reached equilibrium is not required.
[0014] The present invention will hereinafter be described in detail.
[0015] The organic amine component of the soap produced by the method of the invention may
for example be diethanolamine, triethanolamine, triethylamine, trimethylamine or diethylamine.
Triethanolamine is particularly preferable. A single organic amine may be used, or
two or more organic amines may be employed in combination.
[0016] The alkali quantity corresponding to 1 saponifying equivalent, for example, can be
obtained as the alkali quantity necessary for neutralizing the acid derived from the
fatty acid, calculating the acid quantity from the weight and the molecular weight
of the fatty acid.
[0017] The fatty acid or the animal/vegetable oil used for the transparent solid soap according
to the present invention may be those generally employed as fundamental sources. As
the fatty acid, there can be specifically exemplified stearic acid, lauric acid, myristic
acid, palmitic acid and behenic acid and the like. Synthetic or natural fatty acids
may be used. Further, as the animal/vegetable oil, specifically, beef tallow, coconut
oil and hydrogenated coconut oil, and the like, which is previously hydrolyzed into
the fatty acid, may be used or may be used intact.
[0018] Further, the quantity of the fatty acid used as a raw material for the transparent
solid soap according to the present invention is preferably from 30% to 60% by weight,
more preferably from 35% to 57% by weight and, much more preferably, from 37% to 55%
by weight. Moreover, the quantity of triethanolamine used is preferably from 30% to
50% by weight, more preferably from 31% to 47% by weight, and even more preferably
from 32% to 45% by weight. Furthermore, the quantity of sodium hydroxide used is preferably
from 5% to 10% by weight, more preferably from 5.5% to 9.5% by weight, and much more
preferably from 6% to 9% by weight.
[0019] In the transparent solid soap according to the present invention, if in such a range
as not to spoil the effects of the present invention, there can be optional components
generally used for the soap in addition to the indispensable components described
above. As the above optional components, there may be exemplified, e.g., antioxidant
such as BHT, chelating agent such as EDTA and hydroxyethane diphosphonic acid, antiseptic
agent such as methylparaben, coloring matters, pigments, fine particles, mica titanes
with interference colors, pearl agent such as mica titanes, perfume, and surface active
agent such as POE added sodium alkylsulfate.
[0020] Although the transparency might be reduced to some extent by the inclusion of such
optional components, and depending on the quantity added, the soap can become highly
lustrous and conspicuous in colour.
[0021] The transparent solid soap according to the present invention can be manufactured
by an ordinary transparent solid soap manufacturing method. For example, the transparent
solid soap can be manufactured by a frame kneading method of saponifying the fatty
acid or the animal/vegetable oil with alkali, melting a mixture by heating that are
mixed with other components as the necessity arises, pouring the mixture into a mold
and solidifying it by cooling.
[0022] Moreover, the transparent solid soap can be obtained by carrying out pellet processing
such as pressurization-molding, i.e., by a mechanical kneading method. Further, if
pressurization-molded by use of the pellet into which the transparent soap material
of the present invention is molded and the pellet manufactured from an ordinary opaque
soap material, a transparent solid soap having a stripe pattern is to be obtained.
Moreover, a flower-shaped molding is made of an opaque soap and embedded in and wrapped
with the transparent soap material of the present invention by the frame kneading
method, thereby making it possible to obtain a transparent solid soap with the molding
embedded in and wrapped therewith. Further, if a printed thin film composed of carboxymethylcellulose
is embedded in and wrapped therewith, it is feasible to obtain the transparent solid
soap with a picture drawn inside.
[0023] The present invention will hereinafter be described in detail by means of non-limiting
Examples. Note that numerical values of prescription are parts by weight as far as
no particular indications are given.
Examples 1 - 6
[0024] The transparent soap material is manufactured according to the formulation of Table
1 which follows. Concretely, the components of Table 1 are scale-put into a heating
kneader, kneaded for 2 hours at 80°C, and, through a pelletizing operation by a hot
roll and a pelleter, the transparent soap material is obtained as a pellet. When the
moisture content of this pellet is obtained by Karl Fischer moisture content titration
, the moisture content of the pellet comes to the result shown in Table 1. When the
component composition of the pellet is calculated from this moisture content, the
component composition as shown in Table 2 is obtained. Note that the quantity of alkali
with respect to fatty acid is as shown in Table 3.
Table 1
Component |
Example 1 |
Example 2 |
Example 3 |
Coconut oil fatty acid |
40 |
40 |
40 |
Beef tallow fatty acid |
160 |
160 |
160 |
Triethanolamine |
140 |
145 |
160 |
Sodium hydroxide |
34 |
29 |
26 |
Water |
86 |
81 |
79 |
State of pellet |
Transp a-rent solid-state |
Transp a-rent solid-state |
Transp a-rent solid-state |
Pellet moisture content (weight %) |
5.4 |
6.2 |
4.8 |
Component |
Example 4 |
Example 5 |
Example 6 |
Coconut oil fatty acid |
40 |
40 |
40 |
Beef tallow fatty acid |
160 |
160 |
160 |
Triethanolamine |
170 |
175 |
160 |
Sodium hydroxide |
34 |
26 |
31 |
Water |
86 |
79 |
84 |
State of pellet |
Transp a-rent solid-state |
Transp a-rent solid-state |
Transp a-rent solid-state |
Pellet moisture content (weight %) |
6.1 |
5.5 |
5.6 |
Table 2
Component |
Example 1 |
Example 2 |
Example 3 |
Coconut oil fatty acid |
10.2 |
10.0 |
9.7 |
Beef tallow fatty acid |
40.9 |
40.1 |
39.5 |
Triethanolamine |
35.8 |
36.4 |
39.5 |
Sodium hydroxide |
8.7 |
7.3 |
6.4 |
Water |
4.4 |
6.2 |
4.8 |
Component |
Example 4 |
Example 5 |
Example 6 |
Coconut oil fatty acid |
9.3 |
9.4 |
9.7 |
Beef tallow fatty acid |
37.2 |
37.7 |
38.6 |
Triethanolamine |
39.5 |
41.3 |
38.6 |
Sodium hydroxide |
7.9 |
6.1 |
7.5 |
Water |
6.1 |
5.5 |
5.6 |
Table 3 (Unit: Saponifying Equivalent)
|
Alkali quantity to fatty acid |
Example 1 |
2.37 |
Example 2 |
2.24 |
Example 3 |
2.28 |
Example 4 |
2.65 |
Example 5 |
2.41 |
Example 6 |
2.45 |
Examples 7 - 12
[0025] The transparent solid soap is obtained by pressure-forming the pellet-like transparent
soap material in the Examples 1 - 6. In this transparent solid soap,the change in
weight is less than 5% even when preserved at 40°C for one month, and, further, neither
variation in the transparency nor crystal deposition can be seen.
Example 13
[0026] The transparent soap material is manufactured according to the scaling prescription
in Table 6 which follows. Concretely, the prescription components in Table 6 are scale-put
into a heating kneader, kneaded for 2 hours at 80°C, and, through the pelletizing
operation by a hot roll and a pelleter, the transparent soap material is obtained
as a pellet. Note that according to the prescription in Table 6, the alkali quantity
relative to the fatty acid is 2.45 saponifying equivalents.
[0027] The moisture content of this pellet was 5.1% by weight (which is based on the Karl
Fischer moisture content titration). This pellet was a lustrous white solid body.
This soap material showed no variation in weight even when preserved at 40°C for one
month
Table 6 (Scaling Prescription)
Component |
Mixing quantity |
Stearic acid |
30 |
Palmitic acid |
13 |
Sodium hydroxide |
6.7 |
Triethanolamine |
32 |
BHT |
0.1 |
Hydroxyethane diphosphonic acid |
0.1 |
Water |
17.1 |
Titanium oxide |
1 |
Example 14
[0028] The transparent soap material is manufactured according to the scaling prescription
in Table 7 which follows. Concretely, the prescription components in Table 6 are scale-put
into a heating kneader, kneaded for 2 hours at 80°C, and, through the pelletizing
operation by a hot roll and the pelleter, the transparent soap material is obtained
as a pellet. Note that according to the prescription in Table 7, the alkali quantity
relative to the fatty acid is 2.45 saponifying equivalents.
[0029] The moisture content of this pellet was 5.1% by weight (which is based on the Karl
Fischer moisture content titration). This pellet exhibited no change both in the weight
and the transparency even when preserved at 40°C for one month.
Table 7 (Scaling Prescription)
Component |
Mixing quantity |
Stearic acid |
30 |
Palmitic acid |
13 |
Sodium hydroxide |
6.7 |
Triethanolamine |
32 |
BHT |
0.1 |
Hydroxyethane diphosphonic acid |
0.1 |
Water |
18.1 |
Example 15
[0030] The pellet in the example 13 is melted by heating, poured into a silicone rubber
mold and solidified, thus manufacturing a molding of a flower of rose. This molding
is placed in a frame, and the transparent soap material molten by heating in the example
14 is softly poured and solidified by cooling, thus obtaining a transparent solid
soap including a flower. This transparent solid soap exhibited neither a change in
the transparency of the transparent portion nor a change in weight even when preserved
at 40°C for one month.
Industrial Applicability
[0031] The transparent solid soap according to the present invention can be easily produced
without requiring fine control of the moisture content or a maturing period till reduction
in weight has been settled, and, besides, exhibit high stabilities of transparency
and of weight with the passage of time.