GB2305932A - Soap bar - Google Patents

Abstract

A soap bar comprises from 10% to 99% by weight of the bar of at least one soap base and from 0.1 to 10% by weight of the bar of at least one temperature sensitive dye. The soap bar is operative to change colour when the temperature of the bar moves beyond a transitional temperature for the temperature sensitive dye.

Description

sOAP BAR The present invention relates to a soap bar.

Soap bar cleansing products are well known and have been available for many years. It is conventional to produce soap bars in one of a range of colours by incorporating a dye into the soap. It is also known to incorporate pearlescent agents into soap bars or to provide marbled soaps, such as that marketed in the U.K.

under the trade mark SHIELD.

The present invention seeks to provide a novelty soap bar which would appeal, in particular, to children.

According to the present invention there is provided a soap bar comprising the following components: from 10% to 99% by weight of the bar of at least one soap base and from 0.1 to 10% by weight of the bar of at least one temperature sensitive dye, wherein the soap bar is operative to change colour when the temperature of the bar moves beyond a transitional temperature for the temperature sensitive dye.

Thus the present invention provides a soap bar, the colour of which changes when subjected to elevated temperatures. A typical transitional temperature for the temperature sensitive dye would usually be in the range from 10 C to 500C and would typically be in the range from 30-35"C. The temperature change is ideally reversible, i.e. the bar reverts to its original colour on cooling. The temperature reversibility would ideally be repeatable for the life of the product.

The soap base preferably includes the salts of fatty acids derived from tallow, coconut, palm, palm kernel oil, palm stearine oil or blends thereof. The cation is preferably sodium, potassium or triethanolammonium. The soap base may be made by either the Alfa-Laval method or the pan process and is usually extruded into noodles.

These processes are well known in the art and need not be described in detail here.

The temperature sensitive dyes are available from Magna Colours of Barnsley, Yorkshire, under the trade mark VARIOTHERM. The dyes are available in a range of different colours, such as red, blue or black. The VARIOTHERM dyes consist of spherical particles which are approximately 5 to 30 microns in diameter. The VARIOTHERM dye/colour has a pigmenting property. The physical and chemical features of the VARIOTHERM dye is a function of the capsule film, whilst light fastness is related to the property of the colouring matter involved.

The capsule film of VARIOTHERM is water insoluble.

The bar preferably further comprises from 0 to 0.8% by weight of the bar of at least one non-temperature sensitive colouring agent of the type conventionally used in personal care formulations. Typical colouring agents are those dyes/pigments supplied by D.F. Anstead including for example Pigment Red No. 5 (CI 12490), Pigment Yellow No. 1 (CI 11680), Pigment Green No. 7 (CI 74260), Pigment Blue No. 15 (CI 74160), Pigment Orange 43 (CI 71105).

The bar may further comprise from 0 to 5% by weight of the bar of additional additives such as fragrance, natural oils, moisturisers, preservatives, for example magnesium silicate. Such additional additives are well known in this field and are not listed in detail herein.

The invention will now be described further by way of the following example.

Example % w/w 80/20 soap base 93.4% VARIOTHERM dye (Vermillion paste 25) 2.5% Irgalite Yellow 10G Colour (CI 11710, 1% solution) 3.0 Perfume 1.0% EDTA preservative 0.1% In this case an 80/20 blend of sodium tallowate and sodium cocoate (or sodium palm kernelate) was used. The soap base included magnesium silicate and approximately 11% by weight of water.

The blended soap base was milled 3 times to ensure thorough mixing. Then the base was plodded and a billet extruded. The extruded bars were stamped into shaped bars.

At room temperature the red VARIOTHERM colour appears in the bar and as the temperature rises as the bar is placed under warm bath water to 30-350C, the red VARIOTHERM colour disappears and the bright yellow (standard) colour appears. On cooling to room temperature, the red VARIOTHERM colour reappears.

These coloured soap bars indicate the temperature rise in the bath through the disappearance of one colour and appearance of another colour, making bathing enjoyable for children.

It is to be understood that the above described example is by way of illustration only. Many modifications and variations are possible.

For example any temperature sensitive dye can be used as long as it operates within the specified temperature range. The dye may gain or lose colour at elected temperatures or simply change colour. Also any second dye can be used - yellow was merely used for its aesthetics. Without the second dye the bar would change from, in this case, red to white and back again.

Claims (7)

1. A soap bar comprising the following components: from 10% to 99% by weight of the bar of at least one soap base and from 0.1 to 10% by weight of the bar of at least one temperature sensitive dye, wherein the soap bar is operative to change colour when the temperature of the bar moves beyond a transitional temperature for the temperature sensitive dye.

2. A soap bar as claimed in claim 1, wherein the said transitional temperature for the temperature sensitive dye is in the range from 10"C to 500C.

3. A soap bar as claimed in claim 1 or claim 2, wherein the said transitional temperature for the temperature sensitive dye is in the range from 30"C to 500C.

4. A soap bar as claimed in any preceding claim, wherein the bar reverts to its original temperature on cooling below the said transitional temperature.

5. A soap bar as claimed in any preceding claim, wherein the soap base includes the salts of fatty acids derived from any of the following or blends thereof:- tallow, coconut, palm, palm kernel oil, or palm stearine oil.

6. A soap bar as claimed in any preceding claim, wherein the bar comprises from 0 to 0.08% by weight of the bar of at least one non-temperature sensitive colouring agent.

7. A soap bar substantially as described herein with reference to the example.