Лако-красочные материалы — производство

The client has asked for a recommended formulation for a luxurious soap bar, based solely on vegetable fats (Figure 9.2). A high-quality palm-coconut base that is widely available in Europe should be suitable, but it was felt that such a premium product should contain some additional materials to convey ‘added value’. Thus, a powdered cationic polymer is incorporated, which deposits a moisturizing film on the skin and helps to promote a rich, creamy lather. Titanium dioxide, a standard additive to any soap, provides greater opacity (and, to some extent, whiteness) to the bar and a variety of pigment pastes, which are a International Nomenclature for Cosmetic Ingredients (INCI) names are used through­out, since this is the standard recognized in the industry.

Figure 9.2 Conditioning vegetabe soap formulation (a 80:20 palm: coconut soap base, ex Unichema Int., Gouda, Netherlands; bpolyquaternium-7, ex Chemviron Speciality Chems., Overijse, Belgium)

stable in the alkaline environment (around pH 9-10) and to light, are available to colour the soap any desired shade. A white soap also contains colourant (called a white slurry, consisting of a small amount of a blue pigment and a fluorescent whitening agent) because raw soap base is, in fact, a dull, yellowish-cream colour.

What sort of stability issues are there likely to be in such a soap formulation? Firstly, the colour of the fragranced soap is as yet undecided; if it is to be white, then the degree of discoloration which can be tolerated is likely to be a lot less than if the bar is coloured to ‘match’ the fragrance type. The disastrous consequences of incorporat­ing too much vanillin into a fragrance for white soap are shown in Figure 9.3. This severe browning reaction begins to occur after a matter of hours and cannot be prevented, since it results from a chemical reaction caused by the high pH of the soap, which is accelerated by exposure to light. For this reason, vanillin is rarely a major ingredient in soap perfumes. It may be used in small amounts in a soap if it is known that it is to be dyed a strong colour. There are alternative materials with vanilla-type odours that can be used instead, such as ethyl vanillin (which, although still discoloring, can be used at a lower level), Ultravanil® and Benzoin Hypersoluble P85®. Other perfumery materials that can cause a less radical, but still potentially significant, change in the colour of a white bar include eugenol, isoeugenol, heliotropin, certain mosses, Schiff’s bases, citral, indole, etc. These

also need to be avoided, substituted or used only very sparingly and colour changes measured to ensure they stay within specification, even after storage at high temperature (see later).