2005 ANNUAL SCIENTIFIC SEMINAR 341 2) Average molecular weight (Mw), always keep in mind that polymers are never just one exact molecular weight, there is always a distribution. Exl)erimentally measured molecular weight of polymers are dependent on the measurement technique used, and take different names/symbols. In addition, often, for traditional reasons. the molecular weight of polymers is reponed in terms of K \'alue. The higher the K value the larger is the a,·erage size of the molecules of the polymer. Some definitions related to different molecular weight: Mn = number average molecular weight measured by methods that count the number of molecules in the system Mw = weight average molecular weight, measured by methods in which the size of the molecule determines the magnitude of the response. Mv = viscosity molecular weight, measured by intrinsic viscosity Polydispersity = Mw/Mn also referred to heterogenaity index. 3) Solubility of the polymer: in water, ethanol or other sol\'ents. ➔) Stiffness ability of the polymer, this deterrnin�s the t)l)C of styling action that the polymer will be able to perform. For hair sprays and gels it is usually hold, stiffness or 'crunch', for mousses it can be but usually it takes the form of style, \'Olume and control. There are plenty of ,·ariations on basic laboratories test methods for a first assessment of this property. 5) For aerosol spray formulations it is important to know the level of propellant compatibility. Things to watch out for: 1) Possible impurities of by-products that could be of specific relevance to specific markets, e.g.: Porposition 65 ingredients, CMR (carcinogenic. mutagcnic, toxic to reproduction) substances etc. 2) Volatile Organic Compounds (VOC) content. The maximum limit for the content of VOC in different formulations is set by each State separately, or by EPA on a National level. The most affected categories are the ones of aerosols, sprays or mousses, and most recently hair gels. Ethanol and propel I ants are among the ingredients that are greatly affected by this regulation note that often ethanol is the solvent for a raw material although the INCi name does not list it. 3) Origin of the raw materials used to produce the polymer: vegetable, synthetic or animal deri,·cd. ➔) PreserYative used in the polymer. 5) Shelf life of the product, age of the sample being used for your development work ! 6) Various certifications and commonJy used acronyms: GMO-free (Genetically Modified Organism). Kosher, NF (National Forrnulary), USP (United States Pharmacopoeia), cGMP (current Good Manufacturing Procedures).
342 JOURNAL OF COSMETIC SCIENCE HAIR S1YLING OVERVIEW AND FORMULATION APPROACHES Melissa J. Vitale National Starch & Chemical Company, Bridgewater, NJ In recent years, the global hairstyling market has been segmented into numerous product forms and performance choices. Traditional styling formulations, including hairsprays, mousses, and gels, are still considered to be the key applications in a styling product line. This paper will discuss the ingredients and strategies necessary to formulate an effective hairspray, mousse, and gel product. Hairspray Hairspray products are typically used to hold a finished hairstyle in place and protect it from falling apart in humid environments. Some hairsprays, particularly non-aerosol products, can be used as working sprays that are applied during the styling process for hair manageability and control. In the United States, most aerosol and non-aerosol hairspray products are 55% VOC compliant formulas due to the CARB and Ozone Transport Commission (OTC) regulations. Typical 55% VOC hairspray formulations, including ingredients and ranges, are listed in Table l. The fixative polymer is the key raw material in any styling formulation. The pol ym er provides the hold, stiffness, and adhesion of hair fibers to fix the style. It also provides high humidity curl retention properties. Resins that have a high molecular weight and modulus (toughness) with some hydrophobic character will typically provide the strongest hold and humidity resistance when effectively delivered from a hairspray system. Examples of common hairspray polymer chemistries for 55% VOC systems include acrylates (Acrylates Copolymer, Octylacrylamide/ Acrylates/Butylaminoethyl Methacrylate Copol ym er), acetates (VA/CrotonatesNinyl Neodecanotate Copolymer), esters of PYM/MA, maleimide copolymers (Isobutylene/Ethylmaleimide/Hydroxyethyl Maleimide Copolymer), polyesters (Diglycol/CHDM/ Isophathalates/SIP Copolymer), and polyurethanes (Pol yu rethane-I, Polyurethane-14 (and) AMP-Acrylates Copolymer). Pol ym ers that contain carboxylic acid groups will need to be neutralized to balance shampoo removability with good humidity resistance. Varying the degree of neutralization can affect several properties of the hairspray system, including solution viscosity, film hardness film clarity, polymer solubility, tackiness, humidity resistance, removability, and propellant tolerance. These neutralization differences allow the formulator some additional latitude to modify product performance. When formulating a 55% VOC hairspray, the ethanol solvent and typical propellant(s) (e.g., hydrocarbons, dimethyl ether) cannot exceed 55% of the formulation. Therefore, water (an inexpensive non-VOC solvent) is now becoming a major component of the hairspray system. Higher levels{ 25%) of water in a hairspray formula start to deteriorate product performance, including very slow setting and drying time, high formula surface tension, high formula viscosity, and can corrosion potential. The high surface tension and viscosity impede the polymer droplets from flowing down the hair and forming spot/seam welds, thus providing poor holding power. Solvent and propellant ingredients that are exempt from the VOC rule, including acetone and methyl acetate solvents and Hydrofluorocarbon 152A propellant, may replace a portion or all of the water in the formula to attenuate these performance issues. However, ingredient and packaging compatibility, odor, and cost need to be taken into consideration before using these alternative components. Additives are becoming more important in enhancing the performance of 55% VOC hairspray systems. They can be used to aid dry combing, reduce flaking by resin plasticization, increase gloss, provide UV protection, improve sprayability, improve flow down the hair, and prevent can corrosion. For example, silicones (dimethicone copolyols) are commonly used to plasticize the resin to reduce flaking and improve combing. Small levels of Cyclopentasiloxane can reduce formula surface tension dramatically, allowing for improved sprayability and flow down the hair. In addition, most high water aerosol hairspray systems now require corrosion inhibitors (e.g., sodium/ammonium benzoate, cyclohexylamine, etc.) to prevent rust in tin-plated steel cans. Styling Mousse Mousse products are hair styling tools that provide hold and control, increase body and volume, improve wet and dry combing, improve wet and dry feel, and provide overall manageability during the styling process. The components of mousse formulations can be similar to hairsprays, however they are mainly aqueous and usually contain conditioning polymers and surfactants/emulsifiers to produce a foam. Mousses can be applied from an aerosol foam, aerosol spray foam, or non-aerosol using special pump foamer packaging. The current CARB and OTC regulations for mousses and foams are 6% VOC systems. Typical 6% VOC compliant mousse formulations are listed in Table l below. In a typical aerosol mousse formula, the concentrate and propellant are two separate phases and must be shaken immediately before use. When the mousse is shaken, the propellant is emulsified in the aqueous phase and expands when
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