EP0138597B1

EP0138597B1 - Detergent bars

Info

Publication number: EP0138597B1
Application number: EP84307006A
Authority: EP
Inventors: Stephen Anderson; John Martin Behan; Terrence Allan Clarke
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1983-10-14
Filing date: 1984-10-12
Publication date: 1989-08-23
Also published as: AU575347B2; JPS60104198A; AU3417684A; DE3479517D1; CA1232818A; GB8327617D0; ATE45765T1; EP0138597A3; BR8405166A; EP0138597A2; ZA847992B; IN159933B

Abstract

The effectiveness of the deodorant composition disclosed in UK 2016507 in soap formulations can be improved by incorporating the compositions in a transparent soap formulation containing rosin.

Description

Field

This invention relates to detergent bars and in particular to bars containing soap, that is water soluble salts of long chain (C₂ to C₂₂) monocarboxylic acids, and having a transparent phase structure.

Background of the invention

The presence of a transparent phase structure in a soap bar will usually provide the bar with transparent properties. The literature in the field of soap technology describes how soap bars can be provided with transparent properties by suitable selection of processing conditions and components. Quantitative measurements of transparency can be made using methods described in the literature, for example visual print size, voltage and graded lines, but there is a general acceptance of the term transparent to describe a class of soap bars. A transparent soap incorporating rosin is disclosed in US―A―1 626 708.
The supply of a skin deodorancy effect from a detegency bar intended for personal washing has long been viewed as a desirable property. A number of deodorant materials have been described in the literature and include germicides and deodorant compositions which are perceivable by the olfactory sense and can be used as a perfume material or as a base for a perfume material. Examples of deodorant compositions of this latter class are disclosed in, for example UK patent specification GB-A-2016507 (Unilever).

General description of the invention

It has been found that the deo-effectiveness of a deodorant material having a result of from 0.5 to 3.5 in a Deodorant Value Test described in UK 2016507 is increased when incorporated in a rosin containing transparent bar. The rosin will usually be present in the range from about 1 % to about 30% by weight of the bar preferably above about 4% and the deodorant composition in the range from about 0.1 % to about 10% by weight. The increase in the deodorant composition effectivenss derives from the matured transparent phase of the soap which may, in some product compositions, not be appreciated in the form of a transparent bar. Thus the presence of an opaque filler, for example, titanium dioxide or silica, would mask the total bar property of transparency but the existence of the transparent phase structure would provide an increase in the deo-effectiveness. The method of forming the transparent phase structure is not critical; the intense working and casting methods form bars which provide an environment in which the deodorant material has increased effectiveness.
The transparency will increase to a commercially useful level during maturation. This process will usually be allowed to proceed at ambient temperature i.e., about 20°C but higher temperatures i.e., up to about 30°C and up to about 40°C are usable for some compositions. The transparent phase will preferably satisfy the test requirements of US―A―2970116 (Kelly) and have a Translucency voltage of 30 or less.

The deodorant value test

The deo-effectiveness of deodorant compositions is measured as the Deodorant Value (DV) by the method described in GB-A-2016507.
In this test the deodorant value of a deodorant composition is measured by assessing its effectiveness, when contained in a standard soap bar atua standard concentration, in reducing body maladour when the standard soap bar is used to wash the axiallae (armpits) of a panel of humand subjects.
The choice of a soap base is not critical to the performance of the test but as illustrative of the conduct of the test in this respect the procedure followed in the preparation of the base is included in the description of the test.
Standard soap bars are prepared as follows, all amounts given being by weight.
As soap base there is used a neutral wet sodium soap containing 63% of total fatty matter of which 82% is tallow fatty acid and 18% is coconut oil fatty acid. To a homogeneous mixture of 9000 parts of this soap base and 340 parts of free coconut oil fatty acid at 80°C are added with mixing 9.4 parts of a 20% aqueous solution of tetrasodium ethylenediamine tetraacetate, 2.2 parts of a 60% aqueous solution of 1-hydroxyethane-1,1-disphosphonic acid and 7.2 parts of butylated hydroxy toluene (BHT) anti-oxidant dissolved in a little methylated spirits and the temperature of the mass is raised to 140°C under superatmospheric pressure. The mass is then sprayed at about 30 mm of mercury, to produce a dried soap composition which is collected and extruded at 30°C as noodles of about 12% moisture content.
9,770 parts of the soap noodles thus obtained are mixed at ambient temperature with 150 parts of the deodorant composition to be tested, together with 30 parts of a titanium dioxide opacifier and 50 parts of a colourant suspension. The resulting mixture is milled and stamped into tablets. The deodorant composition to be tested is therefore present at the standard level of 1.5%. These tablets are the test soap bars described as 80/20/5 soap base in the examples, and consist of 80 parts tallow soap and 20 parts coconut oil soap, 5 parts of this soap mixture being free fatty acids expressed as coconut oil fatty acid.
Examples of alternative soap bars are those prepared in a similar manner except that they consist of 80 parts tallow soap and 20 parts coconut oil soap, with no added free fatty acid (described as 80/20 soap base), or 70 parts tallow soap and 30 parts coconut oil soap, with no added free fatty acid (described as 70/30 soap base), or 55 parts tallow soap and 45 parts of coconut soap, 7.5 parts of this soap mixture being free fatty acids expressed as coconut oil fatty acid (described as 55/45/7.5 soap base).
Control soap bars are prepared in a similar manner except that the deodorant composition is omitted. In other respects, the control bar should only contain those additives conventionally present in personal washing products and for the purpose in the amount conventionally used in the art. For example, it is permissible as indicated in the foregoing description to include antioxidants in the control bar, but these should be present only in the amount required to stabilise the soap base.
The test is conducted as follows:

A team of 3 Caucasian female assessors of age within the range of from 20 to 40 years is selected for olfactory evaluation on the basis that each is able to rank correctly the odour levels of the series of aqueous isovaleric acid solutions listed in Table 1 below, and each is able to detect the reduction in body odour following application to the axillaie of human subjects of soap containing 2% germicides, according to the procedure described in Whitehouse and Carter, Proc. Scientific Section of the Toilet Goods Association, 48, 31, (1967).
A panel of 50 human subjects for use in the test is assembled from Caucasian male subjects of age within the range of from 20 to 55 years. By screening, subjects are chosen who develop axilliary body malodour that is not unusually strong and who do not develop a stronger body maladour in one axilla compared with the other. Subjects who develop unusually strong body malodour, for example due to a diet including curry or garlic, are not selected for the panel.

For two weeks before the start of a test, the panel subjects are assigned a non-deodorant soap bar for exclusive use of bathing and are denied the use of any type of deodorant or antiperspirant. At the end of this period, the 50 subjects are randomly divided into two groups of 25. The control soap bars are then applied to the left axillae of the first group and the right axillae of the second, and the test soap bars are applied to the right axillae of the first group and the left axillae of the second.
The soap bars are applied by a technician using a standard technique in which a wet flannel is soaped with the soap bar for 15 seconds, the axilla is washed with the soaped flannel for 30 seconds, then wiped with a water rinsed flannel and dried with a clean towel. Each subject then puts on a freshly laundered shirt, and 5 hours after application the odour intensity of each subject is assessed, the left axilla of each subject being assessed before the right. The application and assessment are carried out on each of four successive days.
The odour intensity is evaluated by all three assessors who, operating without knowledge of the soap bars used for each subject or the result of evaluation of their fellow-assessors, sniff each axilla and assign a score corresponding to the strength of the odour on a scale from 0 to 5, with 0 corresponding to no odour and 5 representing very strong odour. Before evaluation each subject stands with his arms against his side; he then raises one arm straight overhead, flattening the axilla vault and making it possible for the assessor's nose to be brought close to the skin, the assessor makes an evaluation and the procedure is repeated with the other axilla.
Standard aqueous solutions of isovaleric acid which correspond to each of the scores 1, 2, 3, 4 and 5 are provided for reference to assist the assessors in the evaluation. These are shown in Table below.
The scores recorded by each assessor for each soap bar are averaged and the average score of the test soap bars deducted from the average score of the control soap bars to give the deodorant value of the deodorant composition present in the test soap bars.
As a check that the selection of panel subjects is satisfactory for operation of the test, the average score with the control soap bars should be between 2.5 and 3.5.
Although the standard concentration of a deodorant composition for the purposes of this test is 1.5% by weight of the standard soap bar, soap bars containing concentrations of the deodorant composition above or below this figure will in practice yield correspondingly higher or lower "deodorant values".

Other test methods used

GB-A-2016507 also discloses the lipoxidase test, by which the lipoxidase inhibiting capacity is measured, and the morpholine test from which the Raoult variance ratio is derived.

Constituents of the soap formulation

i) Rosin, which is a wood derived material, contains about 90% of rosin acids which provide a detergent product on neutralisation. A general description of rosin and its properties will be found in 'Soap Manufacture' Vol. I by J. Davidsohn et al (Interscience 1953).
ii) The water soluble salts of long-chain monocarboxylic acids will usually be the sodium and potassium salts with the former being preferred. Commercial transparent soaps may contain a proportion of potassium soap but this is not essential. The long-chain acids will be derived from triglycerides of animal or vegetable origin, for example tallow, coconut, palm and palm kernel. Synthetic acids, for example those obtained by the oxidation of paraffins, may also be used as components.
iii) The deodorant compositions are described generally and specifically in GB-A-2016507. These compositions will usually be prepared from constituents selected from six defined classes of organic compounds.

Preferably the soap bar will include a deodorant composition consisting essentially of from about 45 to 100% by weight of at least five components satisfying requirements stated below and from 0 to about 55% by weight of other materials referred to as "ingredients" each of the components being selected from components having a lipoxidase inhibiting capacity of at least 50% and components having a Raoult variance ratio of at least 1.1, the components and ingredients being so chosen that the deodorant value of the deodorant composition is within the range 0.50 to 3.5.
Each component should be allocated to one of the six classes. These classes are:

Class 1-Phenolic substances:
2-Essential oils, extracts, resins, "synthetic" oils (denoted by "AB"):
3-Aldehydes and ketones:
4-Polycyclic compounds:
5-Esters:
6-Alcohols.

In attributing a component to a class, the following rules are to be observed. Where the component could be assigned to more than one class, the component is allocated to the class occurring first in the order given above: for example clove oil, which is phenolic in character, is placed in Class 1 although it otherwise might have been allocated to Class 2. Similarly, 2-n-heptyl cyclopentanone which is a polycyclic ketone is attributed to Class 3 instead of Class 4.
Specific examples of the perfume components are:

Class 1-(Phenolic Substances) iso-Amyl salicylate, Benzyle saIicyIate, CarvacroI, Clove leaf oil, Ethyl vanillin, iso-Eugenol, LRG 201, Mousse de chene Yugo, Pimento leaf oil and Thyme oil red.
Class 2-(Essential oils, extracts, resins, "synthetic" oils, (denoted by "AB") Benzoin Siam resinoid, Bergamot AB 37, Bergamot AB 430, Geranium AB 76, Geranium oil, Opononax resinoid, Patchouli oil, Petitgrain oil and Pomeransol AB 314.
Class 3-(Aldehydes and ketones) 6 - Acetyl - 1,1,3,4,4,6 - hexamethyl - tetrahydronaphthalene, p - t - Amyl cyclohexanone, p - t - Butyl - alpha - methyl hydrocinnamic aldehyde, 2 - n - heptyl- cyclopentanone, alpha - iso - Methyl ionone and beta - Methyl naphthyl ketone.
Class 4-(Polycyclic Compounds) Coumarin, 1,3,4,6,7,8 - Hexahydro - 4,6,6,7,8,8 - hexamethylcyclopenta - alpha - 2 - benzopyran, 3a - Methyl - dodecahydro - 6,6,9a - trimethyl- naphtho(2,1-b) furan and beta-Naphthyl methyl ether. ,
Class 5-(Esters) o - t - Butylcyclohexyl acetate, p - t - Butylcyclohexyl acetate, Diethyl phthalate, Nonanediol - 1,3 - diacetate, Nonanolide - 1:4, i - Nonyl acetate and i - Nonyl formate.
Class 6-(Alcohols) Dimyrcetol, Phenylether alcohol and Tetrahydromugoul.

The rules are applied only to those components of the deodorant composition present at a level of at least 0.5% by weight of the composition.
The deodorant compositions to which this application relates are minor but relatively expensive constituents of a soap bar. Thus any route to reducing the problem of the economics of their commercial use must be of benefit.

iv) The soap bar may include non-soap detergents in amounts which would not interfere with the production of the transparent phase. Examples of these actives are alkane sulphonates, alcohol sulphates, alkyl benzene sulphonates, alkyl sulphates, acyl isethionates, olefin sulphonates and ethoxylated alcohols.
v) Transparent soaps may contain components to assist in the processing or provision of the desired properties, examples are potassium soaps, glycerol, sorbitol and castor derived soaps.

General & preparative methods

There are two general process routes used to make transparent soaps. The traditional method involves casting the molten soap into frames; this process is known as the cast bar route. More recently transparent soaps have also been made by an energetic working route using mills, mixers, refiners or other suitable devices. These two routes will be discussed separately. Other routes, for example the use of specific additives or cooling steps, can also provide a transparent product; the present invention is not limited in the route by which transparency is obtained.

Cast bar route

There are three main methods used to make cast transparent bars.

i) Full boiled process

The oils and fats are saponified, washed and fitted as for a conventional milled soap. The soap is then dissolved in sufficient alcohol to form an (isotropic) solution. Some variations in technique occur in making the alcohol solution. Either the fitted liquid soap is directly dissolved in alcohol, or the soap is dried to a controlled total fatty matter (TFM) before being dissolved in alcohol or alcohol/water. Various grades of "denatured alcohol", industrial or methylated spirits have been used for this purpose, most containing 90-95% ethanol.

ii) Cold process

The melted oils and fats are mixed with clarifier/filter and with alkali, poured into frames and allowed to react in situ without the external application of heat. In order to completely saponify the oils and fats under these conditions a rather large excess of caustic is required which remains in the final bar; free caustic levels of greater than 1% are common in the type of bar.

iii) Semi-boiled Process

This is the most common route for producing cast transparent soaps. The molten oils and fats, containing aids to transparency such as alcohol, are mixed with the caustic and after the spontaneous saponification has subsided the mix is heated to near boiling point to complete the saponification. The liquid soap together with added components is then cast in frames, cooled and matured.

Formulations of cast transparent bars

Tallow (may be replaced partly or completely by hardened oils with a similar titre), bleached palm oil, coconut oil or palm kernel oil and castor oil are the most commonly used sources of fatty acids (Davidsohn, Soap Manufacture Vol. I). For filling and aids to transparency, sugar, glycerol and alcohol are the main organic raw materials, and sodium carbonate, potassium carbonate and sodium silicate represent the main inorganic raw materials. A number of formulations for cast transparent soap bars are given in the literature.

Energetic working route

The oils and fats can be saponified, washed, fitted and dried using conventional soap-making procedures.
Colouring material and perfume can be incorporated by the standard methods used for conventional soap production. The transparency is generated during an energetic working stage.
Mechanical devices such as blade mixers, mills, refiners and screw extruders can be used to work the soap base.
The plodding, stamping and wrapping stages can be carried out as for a conventional soap line. The transparency will normally increase during a maturation period.
Literature descriptions of this route are found in US-A-2 970 116 (Kelly).

Formulation of energetically worked bars

Formulations are as for conventional, high tallow soaps. They may in addition contain for example potassium soaps, higher levels of glycerol or sorbitol.

Examples

The invention will be specifically described by reference to three examples.

Example I

The following bars were prepared and subjected to panel testing with the regime described in GB-A-2016507. The deodorant composition used was a perfume composition having a Deodorant Value of 1.0 when subjected to the test procedure described previously. The results are given in the Table quoting the difference in perceived odour score with respect to the control.

Bar A-soap bar

The appropriate blend of tallow and coconut fats and oils (80/20) were saponified, washed, fitted and vacuum dried to 12% moisture content using standard soap-making procedures. The dried soap chips, to which no perfume or colouring material were added, were subsequently milled and plodded in the conventional manner to provide an opaque bar.

Bar B-Soap bar containing deodorant composition

This bar was made using the same procedures described for Bar A with the addition of 12% of the perfume having a deodorant value (DV) of 1.0 during the milling stage. The bars were stored for a period of six weeks at 20°C before testing.

Bar C-Transparent soap (rosin-free) containing deodorant composition

The standard pan-room procedures were modified so as to minimise the loss of the more soluble components (glycerol and potassium soap). The fats and oils were added to the nigre of the previous boil. The mix was saponified by using the appropriate blend of NaOH/KOH and fitted so that the neat soap separated on top of nigre and a small amount of lye. The neat soap layer was removed and additional glycerol added (to take account of the small loss the lye) together with additional electrolyte. When vacuum dried to 18% moisture content the composition of the neat soap was such that it contained:
The dried soap chips were placed in a sigma blade mixer and 12% of the perfume used in bar B added. The soap was worked in a Sigma blade mixer at a temperature and water content in the ranges described in US―A―2970116 for a period sufficient to generate a transparent phase. Care was taken to minimise water loss by enclosing the mixer; the temperature was controlled by means of a thermostatic heat-jacket. The bars were subsequently plodded and stamped in the conventional manner. They were then stored at 20°C and matured for 6 weeks before testing.

Bar D-Transparent soap (with rosin) containing deodorant composition

Bar D was made using the procedures for Bar C except for the pre-saponification stage where the rosin (5% by weight of the final bar) was incorporated into the formulation by adding it to the nigre of the previous boil. The fats and oils were then added to the rosin and nigre and the saponification and subsequent stages were carried out as described for Bar C.
The four soap bars were subjected to the odour test described; the difference in Odour Score compared to bar A are given in the Table.
These results demonstrate the use of a rosin containing transparent bar enhances the effectiveness of a deodorant composition. It is seen the transparent bar (rosin-free) has the same difference in Odour Score (allowing for experimental variation) as the standard bar B.

Example II

A deodorant composition was added to a rosin containing transparent bar at a level of 1.5%. The deodorant composition had a deodorant value (DV) of 0.78. The product bar, which had the same base formulation as bar D of Example I, had a difference in Odour Score of 1.36.

Exampe III

A deodorant composition with the formulation below was added to a rosin containing transparent bar at a level of 1.5%.
The deodorant composition had a deodorant value (DV) of 0.60. A comparison bar having the formulation of bar C of Example I had a difference in Odour Score of 0.76. The product bar, which had the same base formulation as bar D of Example I had a difference in Odour Score of 1.35.

Claims

1. A detergent bar composition including a transparent phase, rosin and a deodorant composition having a result of from 0.5 to 3.5 in the Deodorant value Test.

2. A composition according to Claim 1 wherein the deodorant composition is present at a level of at least about 0.1% by weight of the composition.

3. A composition according to Claim 1 or 2 wherein the deodorant composition is present at a level not over about 10% by weight of the composition.

4. A composition according to any preceding claim wherein the rosin is present at a level above about 1% by weight of the composition.

5. A composition according to any preceding claim wherein the rosin is present at a level not over about 30% by weight of the composition.