Toilet soap bars

The invention relates to mild toilet soap bars, comprising blends of soap with one or more coactives. There is a need for mild bars which do not have the processing problems associated with the use of superfatting agents and co-actives, which can be made without difficulty on conventional soap production lines without substantial modification of the lines and yet provide a product with reduced harshness while maintaining lathering and structural properties. Moreover, it is desirable that soap bars should not suffer from the defect of grittiness and also have a composition which contains relatively low levels of the significantly more expensive lauric fats. We have determined that in soap bars which comprise at least 25% wt. on total actives of lauric acid soaps; as the balance of the soaps, non-lauric soaps having an iodine value of less than 45; at least 5% wt. on total actives of one or more synergistic mildness active, and, 2-10% on total actives of free fatty acids and are substantially free of cationic polymer skin mildness aids, there is a significant reduction in bar stickiness while maintaining hardness within acceptable limits. Moreover, the lather volume of the bars is increased without the addition of lauric fats and they do not suffer from grittiness.

FIELD OF THE INVENTION 
The present invention relates to toilet soap bars, particularly to mild 
toilet soap bars comprising blends of soap with one or more coactives. 
BACKGROUND OF THE INVENTION 
For very many years soap bars have been manufactured from fats by 
conversion of triglyceride components of fats into fatty acid salts and 
the formation of these `soaps` into bars. 
Traditionally, the most important fats used in soap manufacture have been 
tallow (a palmatic/stearic fat rendered from animal carcasses) and coconut 
oil (a lauric fat). For the purposes of this specification the words `oil` 
and `fat` are considered interchangeable except where the context demands 
otherwise. The use of other palmitic/stearic fats such as palm oil and 
alternative lauric fats such as palm kernel, babassu or macauba oil is 
known. 
In general the longer chain fatty acid soaps, particularly the less 
expensive C16 and C18 soaps (as obtained from tallow and palm oils) 
provide structure in the finished soap bars and prevent or retard 
disintegration of the soap bar on exposure to water. 
The more expensive, shorter chain, lauric fat-derived, (i.e. lauric acid 
salts) and other soluble soaps (typically as obtained from coconut and 
palm kernel oil) contribute to the lathering properties of the overall 
composition. 
A general problem in the formulation of bar soaps has been that of finding 
a balance between providing structure (generally obtained from the cheaper 
tallow/palm component) and maintaining lathering properties (generally 
obtained from the more costly coconut oil component) at a practical 
overall cost. 
The fatty acid chain length distribution of a range of soap components is 
given below: 
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Chain length 
Tallow Palm Coconut 
Palm Kernal 
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10 0.1 0.0 15.1 6.4 
12 (lauric) 
0.1 0.3 48.0 46.7 
14 2.8 1.3 17.5 16.2 
16 (palmitic) 
24.9 47.0 9.0 8.6 
18 (stearic) 
20.4 4.5 9.0 8.6 
20 1.8 0.3 0.0 0.4 
18:1 (oleic) 
43.6 36.1 5.7 16.1 
18:2 4.7 9.9 2.6 2.9 
18:3 1.4 0.2 0.0 0.0 
Poly unsat 0.1 0.0 0.0 0.0 
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From the table it can be seen that the coconut and palm kernel fats 
(together known as the lauric fats) are particularly rich in the C10-C14 
saturated fatty acids, particularly fatty acid residues derived from 
lauric acid itself. For convenience these fats, containing saturated, 
relatively short chain fatty acids, will be referred to hereinafter as the 
`lauric` fats. This definition includes the coconut, palm kernel, babassu 
or macauba oils as mentioned above. In contrast, tallow and palm oil per 
se are an industrial source of non-lauric fats, especially those 
containing C16 and C18 fatty acid residues: both saturated and unsaturated 
residues being present in almost equal quantities. The C16 and C18 fatty 
acids, together with the longer chain fatty acid are referred to herein as 
`non-lauric` fats. 
A standard measure of the degree of saturation of a fatty acid residue, or 
more usually of a blend of fats or fatty acids, is the so-called iodine 
value. The iodine value of a fatty acid residue is determined by the 
ability of the residue to bind iodine expressed in Mole %. Iodine binds to 
unsaturated fatty acids in proportion to the extent of the unsaturation 
and does not bind in the same manner to saturated fats. Consequently, 
saturated fats have low iodine values, mono unsaturated fats bind around 
100 Mole % iodine and have iodine values (`IV`) of around 100. In contrast 
di-unsaturated fats bind around 200 Mole % and have iodine values 
approaching 200. The 63rd Edition of the CRC Handbook (CRC Press) gives 
the iodine value of beef tallow as 49.5, and for coconut oil gives an 
iodine value of 10.4. 
In typical commercial formulations, soap bars contain from 90-50% fatty 
acid soaps obtained from tallow (i.e. non-lauric fats) and 10-50% of fatty 
acid soaps obtained from coconut (i.e. lauric fats). In particular, in 
countries where tallow is acceptable to consumers, most commercial soap 
formulations comprise 80% tallow and 20% coconut oil. In countries where 
tallow is unacceptable other non-lauric oils and fats, such as palm oil, 
replace tallow. 
Some typical formulations are disclosed in the patents mentioned below: 
GB 989007 (Procter & Gamble) discloses several formulations which comprise 
24-33% coconut soap. The balance of the soaps in these formulations 
(around half the total soaps) are generally tallows (non lauric soaps) 
with I.V. around 48. Some hardened non-laurics are present at up to a 
level of 5%. 
EP 194126 (Procter & Gamble) discloses omega-phase soap formulations with a 
50/50 coco/tallow fat charge of an I.V. about 25. The fats are described 
as comprising `touch-hardened` tallow/coconut fatty acid blends, i.e. no 
substantial hydrogenation of the fats has taken place. The I.V. of tallow 
is normally about 50, and coconut about 10 therefore a total I.V. of 25 is 
not inconsistent with the use of these materials. Touch-hardening is a 
well known technique used to improve the keepability of oils and fats by 
removing oxidation sensitive components and consequently delaying the 
onset of rancidity. 
WO 84/04929 (Henkel) discloses a soap bar comprising at least 40% lauric 
acid soaps. The examples disclose formulations with coconut fatty acid 
soaps of the `Edenor` [RTM] type. 
In addition to fatty acid soaps per se, toilet bars can contain free fatty 
acid. The addition of free fatty acid is known as `superfatting` and 
superfatting at a 5-10% free fatty acid level is known to give a copious, 
creamy lather. Other superfatting agents include citric and other acids 
which function by promoting the formation of free fatty acids in the fat 
blend. 
The conventional soap making process as applied to the manufacture of 
toilet soaps is well documented in the literature. In outline the process 
is as follows. In conventional `wet` soap making, fats, i.e. tallow and 
coconut oil blends, are saponified in the presence of an alkali (typically 
NaOH) to yield fatty acids as alkaline soaps and glycerol. The glycerol is 
extracted with brine to give a dilute fatty acid soap solution containing 
around 70% soap and 30% aqueous phase. This soap solution is dried, 
typically by heating in heat exchangers to circa 130.degree. C. and drying 
under vacuum, to a water content of around 12%, and finished by milling, 
plodding and stamping into bars. 
One known defect in soap bars is so-called `grittiness` It is believed that 
grittiness is caused by overdrying of a portion of the soap during the 
vacuum drying stage which leads to a poor barfeel. The problem of 
grittiness becomes progressively more significant at lower water contents 
and while grittiness can be controlled at laboratory scale it is more 
difficult to prevent grittiness at pilot plant and factory scale. 
The stamping step, is typically conducted at around 250 or more bars per 
minute in a conventional soap line having several bars stamped in 
parallel. 
A problem commonly encountered in stamping of bars is so-called 
`die-blocking`. This occurs when a billet of soap does not release from 
the die after the stamping operation. The consequence of die blocking is 
that the process line must be stopped and the die cleared manually. This 
has a serious effect on throughput, as it is difficult to stop, clear and 
restart the stamping apparatus quickly and safely. During this down-time, 
the soap being produced upstream of the stamping apparatus must be 
diverted and recycled. 
In general, superfatting of bars makes the bars softer and more difficult 
to process, particularly in the plodding and stamping step. For this 
reason, superfatted bars are processed at a low water content: typically 
82% total fatty matter (TFM) as opposed to the more conventional 78% TFM. 
If conventional water contents are used, superfatted bars are difficult to 
manufacture. Preferably superfatted bars are manufactured at a low 
temperature to increase the hardness of the billets and to reduce adhesion 
of the billets to the dies (see Woollatt: `The manufacture of soaps, other 
detergents and glycerine`, page 267, paragraph 6.5.6). As will be 
appreciated, the decrease in the water content of the bars associated with 
superfatting increases the cost of the bars as the proportion of fatty 
matter in the bars is increased. 
A further drawback of compositions containing fatty acid soap is harshness, 
a property which is determined by a number of tests as will be elaborated 
upon hereafter. Known solutions to the problem of harshness include 
reduction of the level of soap present and replacement of the balance of 
the composition by so-called co-actives. It has also been suggested that 
superfatting improves mildness but the improvement is not considered as 
significant as that obtained by the use of co-actives. As with 
superfatting agents, a recognized problem engendered by the presence of 
co-actives is a loss of product structure in the resulting soap bars. 
WO 93/04161 (Procter & Gamble) discloses bars which comprise a mixture of 
soap, a C.sub.14 -C.sub.20 alkyl polyethoxylate nonionic detergent 
surfactant and a C.sub.10 -C.sub.18 acyl isethionate. The soap contains at 
least tallow and is often a mixture with palm stearin and/or coconut. Also 
included in the formulations are cationic polymeric skin mildness aids 
and, as moisturizers, free fatty acids. 
In order to overcome the problem of loss of structure, soap bars which 
comprise co-actives have been manufactured by processes which, while being 
successful, increase the cost of the eventual products. Several such 
processes are known. 
GB 2182343-A (Procter & Gamble) discloses toilet soaps comprising a fatty 
acid soap, a synthetic surfactant co-active and a water soluble polymer. 
In order to reduce the softening effect of the co-active it is necessary 
for some of the soap to be present in the so-called beta-crystalline phase 
and crystallization in this phase can only be achieved by the application 
of high shear (i.e. energetic working) in an additional processing step 
after the drying step and prior to finishing. 
EP 363215 (Colgate) discloses the production of toilet soap bars from soap 
and an ethoxylated surfactant co-active. This soap composition needs to be 
dried to below a critical 5% wt moisture content in order to harden the 
material sufficiently for processing into bar form using conventional soap 
making/forming equipment. This drying step requires additional equipment 
in the form of batch drying trays to be used prior to soap finishing. 
EP 311343 (Procter & Gamble) discloses the combined use of a 
beta-crystalline phase, an ethoxylated nonionic surfactant co-active and a 
water soluble polymer. As described above, these compositional 
modifications require modification of the soap processing line to provide 
for the energetic working needed to form the beta-crystalline phase. 
GB 2243614 (Proctor & Gamble) discloses a beta-phase soap bar prepared by a 
process involving the use of one or more mills (see page 13 line 30ff). 
The bars have less than about 25% short chain soaps (see page 4 line 37ff) 
as the presence of these soaps interferes with the formation of the 
beta-phase. 
It can be seen from the foregoing that each of the known, alternative 
processes for the production of soap bars containing co-actives require 
the provision of further processing apparatus, particularly in the form of 
drying and/or energetic working apparatus and the additional processing 
step which makes use of this apparatus prior to soap finishing. This 
increases the cost of processing and consequently increases the cost of 
the bars produced. 
In addition to provision of structure, it is known that the beta-phase of 
soap provides translucency in certain formulations. It is also known that 
these formulations cannot contain significant quantities of superfatting 
agents (at or above 2% wt) as the presence of larger quantities of 
superfatting agent interferes with the formation of the beta phase. 
From the above it can be seen that there is a need for mild bars which do 
not have the processing problems associated with the use of superfatting 
agents and co-actives, which can be made without difficulty on 
conventional soap production lines without substantial modification of the 
lines and yet provide a product with reduced harshness while maintaining 
lathering and structural properties. It is desirable that soap bars should 
not suffer from the defect of grittiness and it is also desirable that 
these bars have a composition which contains relatively low levels of the 
significantly more expensive lauric fats.

EXAMPLES 
The following materials were used in the preparation of products according 
to the present invention with formulations as given in Tables 1 and 2 
below: 
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Tallow Soap: 
Hardened tallow fatty acid soaps having 
an iodine value of 38. (made in house), 
Coco Soap: Unhardened coconut fatty acid soap. 
(commercially available), 
Nonionic: Table 1: GENAPOL-T200 [RTM ex. 
Hoechst], tallow 20 EO, ethoxylated 
fatty acid, as synthetic mildness 
agent, 
Table 2: C.sub.12 -C.sub.18 alcohol ethoxylate with 
20 EO. 
Coco Acid: Coconut fatty acid [ex. Unichema], 
superfatting agent, 
Perfume: Commercial perfume 
Opacifier: Tiona AC [RTM ex. SCM chemicals], TiO.sub.2 
Antioxidant: 
EDTA (as tetrasodium salt) and ethane- 
1-hydroxy-1,1-diphosphonic acid. 
______________________________________ 
Compositions as given in Tables 1 and 2 were prepared as follows: 
a) a neat soap was prepared comprising hardened non-lauric fatty acid soaps 
(tallow soap) and lauric fatty acid soaps (coco soap), at a temperature of 
85.degree. C., 
b) the product of step (a) was combined with the nonionic and the 
superfatting agents, 
c) the product of step (b) was dried, and perfume and opacifiers added 
using a conventional ribbon mixer, 
d) the product of step (c) was milled, plodded and stamped into bars using 
conventional equipment. 
Products were assessed as regards lather volume, stickiness, grit and 
hardness. 
Lather volume was assessed by a handwash method which closely approximates 
normal consumer habit. The test involves the use of 20 untrained 
volunteers. Each volunteer wears a pair of surgical gloves and lathers the 
bar in a still body of water a temperature of 30.degree. C. The volume of 
the lather produced is measured by submersion of the panelists hands under 
a calibrated collecting funnel. 
Stickiness is scored on a ten point scale with ten representing a 
requirement that the dies need lubricated for every bar stamped, and 1 
indicating that lubrication is needed after stamping every tenth bar. A 
score of zero indicates that no die lubrication was required. 
Hardness was assessed using a sectilometer according to the method 
specified in Woollatt (cit. ultra) at page 259, to give harness in 
10.sup.5 N.m.sup.-2. The minimum acceptable hardness value for processing 
of soap bars is around 2.0. 
Grit was assessed subjectively by a panel of 10 trained operators on a 
scale of 1-5, with 1 representing smooth bars, 2: slightly sandy, 3: 
sandy, slightly gritty, 4: gritty and 5: very gritty. The bars were first 
plunged into water at 20.degree. C. and rotated in the hand for 30 seconds 
before an assessment was made. 
TABLE 1 
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Example 1 2 3 4 
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Tallow Soap 41.1 36.7 44.1 41.7 
Coco Soap 36.7 41.1 31.4 36.1 
Nonionic 9.6 9.6 9.4 9.4 
Coco Acid -- -- 3.8 3.8 
Perfume 1.4 1.4 1.4 1.4 
Opacifier 0.3 0.3 0.3 0.3 
Antioxidant 0.04 0.04 0.04 0.04 
Water to 100% 
Total Coconut 
36.7 41.1 35.2 39.9 
Lather Volume 
39 39 52 55 
Stickiness 5 10 1 1 
Hardness 2.9 2.9 2.7 2.8 
Grit -- 2.6 1.0 -- 
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Examples 1 and 2 are comparative examples which do not contain the 
superfatting agent. Both of these compositions contain relatively high 
levels of coconut fatty acid soaps as compared with typical soap bars and 
consequently, would be expected to give a high lathering product with some 
mildness benefit. However, the cost of raw materials would be higher than 
for conventional bars containing lower levels of coconut fatty acid soaps. 
Example 3 and 4 contain the superfatting agent. In Example 3, an embodiment 
of the invention, a significantly less coconut fatty acids (as soap or 
superfatting agent) is present as compared with Examples 2 and 4. In 
Example 4, a total coconut level similar to that used in Example 2 has 
been employed. 
From the results it can be seen that, the presence of the superfatting 
agent significantly reduces bar stickiness while maintaining hardness 
within acceptable limits. It can also be seen that the lather volume of 
the embodiments of the invention has been significantly increased without 
the addition of further lauric fats, and in the case of example 2, the 
lowest level of coconut fats or fatty acid has resulted a very high lather 
volume. Moreover, it is clear that the bars according to the present 
invention have less grittiness than those according to the prior art. 
For conventional soap bars, containing 20% coconut soap/80% tallow soap, 
typical lather volumes would be 35-40, and the hardness would be around 
2.5. Stickiness for these known bars would approach zero as far fewer 
processing problems are encountered in the manufacture of these 
low-coconut bars. 
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Example 
5 6 7 8 9 10 11 
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Tallow 44.9 43.6 43.1 43.0 41.5 35.3 69.6 
Soap 
Coco 32.5 31.5 31.2 31.1 30.1 39.8 17.4 
Soap 
Non- 9.7 9.4 9.3 9.2 8.9 9.3 0 
ionic 
Coco 0 1.9 3.7 5.6 7.2 0 0 
Acid 
Perfume 
1.7 1.7 1.7 1.7 1.7 1.7 1 
/minors 
Water to 100% 
Lather 34.7 36.0 56.0 54.7 59.9 51.3 44.3 
Volume 
Grit 1.9 -- 1.0 -- -- 2.6 1.8 
Stick- 5 1 10 &lt;1 
iness 
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Examples 5, 10 and 11 are comparative examples. 
The results demonstrate that an increase in the level of coconut level in 
the composition produces an increase in lather volume. 
However, high levels of coconut also result in an unacceptable increase in 
grit (see example 10) and an increased incidence of die blocking. As can 
be seen from a comparison of examples 7 and 10, not only does the addition 
of a fatty acid improve lather volume but it also improves processability 
of bars by reducing the grit score and the incidence of die blocking.