Лако-красочные материалы — производство

Figure 9.6 shows the conditioning shampoo formulation selected. It is based on a blend of a high foaming anionic detergent (sodium lauryl ether sulfate, commonly abbreviated to SLES) and a mild, amphoteric betaine detergent which lowers the irritation potential of the SLES. A cold-mix pearl concentrate is added to give an attractive, white, pearly appearance to the product. Conditioning is provided by several keratin substantive materials, which deposit a thin protective film on the hair, smoothing down the cuticle and preventing static build-up. A copoly­mer of wheat protein/silicone glycol is used, since evidence from the manufacturer shows that this helps to shield the hair from environ­mental damage. Panthenol (commonly called Pro-Vitamin B5 on many leading hair care products) is added to thicken and help repair damaged hair. The final ingredients are preservative (the final choice of which is made by the manufacturer) to prevent microbial spoilage of the product, sodium chloride to thicken the detergent system and, of course, water (which must be deionized and substantially free from bacteria).

The last ingredient, although seemingly innocuous, can cause major problems for the perfumer. In Chapter 7, the perfumer discussed the

Figure 9.6 Frequent-use conditioning shampoo formulation (a cocamidopropyl betaine, ex Henkel Chemicals, Dusseldorf Germany; b hydrolysed wheat protein polysiloxane copolymer, ex Croda Chems, Goole, UK; c glycol distearate and laureth-4 and cocamidopropyl betaine, ex Henkel)

effect that the polarity, or relative water solubility of the perfumery ingredient versus its molecular mass, has on its odour perceptibility from an aqueous detergent system. The nature, quality and level of the detergent(s) and other materials, such as protein conditioners, can sometimes dramatically affect the perfume headspace over the surface of the product and its in-use odour characteristics. The perfumer thus asks the Applications Department to try various fragrance modifica­tions in the detergent base, to assess on smelling the product straight from the bottle and possibly also during a salon evaluation in which a panel of volunteers has the odour of their hair assessed during washing and immediately after rinsing. Equally important is to monitor the smell on washed and dried hair switches (small samples of untreated, virgin hair) for up to 18 hours afterwards, if substantivity or malodour counteractancy is important.

Another problem that the applications chemist may have to contend with is that the perfume may cause shampoo viscosity to decrease or, more often, increase when added to the unfragranced base. If this is a small change, it can be accommodated by varying the level of thickener. However, if dealing with a client’s fully formulated base, this may not be an easy option. In such cases, the perfume formulation needs to be screened for ingredients that are known to affect the viscosity of surfactant systems, such as dipropylene glycol or alcohols, e. g. citro — nellol, which often causes a decrease, and diethyl phthalate, isopropyl myristate or terpenes, which can thicken such solutions quite dramati­cally.

Obviously, the exact formulation of the client’s shampoo under consideration may be unknown to the perfumery house and not follow any previously experienced pattern. If so, it may be necessary to resort to single-ingredient testing of perfumery materials to discover which ones can be safely used without problems. Similarly, chemical reactions could take place between certain perfumery raw materials and active ingredients in a shampoo, such as an anti-dandruff agent like piroctone olamine. Such reactions could lead to discoloration or off- odours in the product, which may only be noticeable after a period of high-temperature storage. As it is a previously tested shampoo base with no problem actives, the formulation given in Figure 9.6 is not expected to give rise to major difficulties but, nevertheless, standard stability testing is initiated when the final fragrances have been selected for submission, to avoid any unpleasant surprises. This is carried out in glass jars, as well as Business Scents Ltd bottles, if available at this stage. Compatibility problems are unlikely to be experienced with polyethylene terephthalate (PET), although it could be affected by citrus and terpene materials. Since the client has specified clear packa­ging, light testing is also necessary (see later).