Pigment dispersion ideal

Uses Emollient for creams/lotions, topical pharniaceuticals pigment dispersant, binder for pressed powds. hair and skin conditioner detad er in deodorant sticks solvent for lipstick dyes carrier and extender for flavors and fragrances Features Nongreasy ideal for oil-free cosmetics and high-pH applies. 

Cosmetics. Castor od and its derivatives are utilized in cosmetic and personal care products. The low pour point and high viscosity produce lubricity and wetting properties desired in Hpsticks. Basic Hpstick contains 20—44 wt % castor od, which also acts as an ideal dispersant for pigments (116). One Hpstick formula contains 38 wt % castor od and 9.5% glycerol monoricinoleate (117). 

A letterpress printing ink is a dispersion of pigment particles in a polymer solution. Deviation from ideality is assured by the presence of polymers of high molecular weight dissolved in solvents of differing polarity so as to disperse particles of differing polarity, shape, and size. 

Pigments ideally should be non-soluble solids with low oil absorption to facilitate dispersion and allow maximum pigment loading, which would also reduce the VOC content of the paint. In addition, pigments should be chemically inert, thermally stable, pure in their composition, and nontoxic. 

Solid masterbatching consists of a high concentration of pigment in a carrier. The carrier can be the plastic with which it is to be compounded, a similar plastic or low molecular weight carriers. The ideal is a masterbatch which is miscible and dispersible with all types of plastic. The pigment level has conventionally been 10-20%. Recently more concentrated masterbatches with 40-60% pigment, usually in a carrier, have been made for use at an approximately 1% addition level. 

Experience has shown that optimum pigment and filler dispersion result when the specific volume of the material charged to the mixer falls within a well-defined range (see Figure 4). The specific volume of the formulation is the volume (in liters) occupied by 1.0 kg of molten compound at 150"C. For a mixer with an approximate free volume of 40 liters, optimum results are obtained using specific volumes of 4.2 to 5.0 liters (10.5-12.5% of mixer free volume). Since specific volume of the melt is directly related to the product formulation, output rates vary volumetrically as a function of product density. Idealized output rates for a 40 hter HIDM are shovra in Figure 5. 

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