Addition of Colorants

Concentrates or masterbatches are consistent, simple, and safe. They usually come in a granular form, in which the concentrated pigment is dispersed in a polymer carrier (such as polyethylene) that is compatible with the matrix resin. The let-down ratio is usually 0.5-2%, depending on colour, host material, and part thickness. 

A typical range will cover around 400 colours, with a minimum order quantity of 2 5 kg, but some suppliers can supply down to 1 kg at a surcharge. Colour matching can also be done, usually on a minimum quantity of 50 kg. There are around 200 producers of colour masterbatch. the leaders being Cabot, Schulmann, Ampacet, and Ferro. 

Whether the colour is added by a specialist compounder or by a good technical processor, the quality depends on dispersion and match. The pigment is dispersed by wetting the particles with the resin, and the size and shape of the particles are therefore of great importance, as also are the rheological properties of the resin matrix. Apart from colour fidelity, good dispersion also plays a role in 

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Ta.loPhospha.ta.tlon, Phosphatation is performed as described above with the addition of color-precipitating chemicals and a series of mud-desweetening steps, which remove a greater amount of color (30—50%), ash, and turbidity. Talo (a trademark of Tate Lyle, pic, U.K.) phosphatation is the process mentioned above that is widely used ia white end refineries. It has almost replaced traditional phosphatation (11). 

Colorless Foods. The principal use of color additives in food is in products containing Htde or no color of their own. These include many hquid and powdered beverages, gelatin desserts, candies, ice creams, sherbets, icings, jams, jeUies, and snack foods. Without the addition of color to some of these, eg, gelatin desserts and soft drinks, all flavors of the particular product would be colorless, unidentifiable, and probably unappealing to the consumer. 

In milk approximately 90% of the yellow color is because of the presence of -carotene, a fat-soluble carotenoid extracted from feed by cows. Summer milk is more yellow than winter milk because cows grazing on lush green pastures in the spring and summer months consume much higher levels of carotenoids than do cows ham-fed on hay and grain in the fall and winter. Various breeds of cows and even individual animals differ in the efficiency with which they extract -carotene from feed and in the degree to which they convert it into colorless vitamin A. The differences in the color of milk are more obvious in products made from milk fat, since here the yellow color is concentrated. Thus, unless standardized through the addition of colorant, products like butter and cheese show a wide variation in shade and in many cases appear unsatisfactory to the consumer. 

Colorants. Color (qv) is used in cosmetic products for several reasons the addition of color to a product makes it more attractive and enhances consumer acceptance tinting helps hide discoloration resulting from use of a particular ingredient or from age and finally, decorative cosmetics owe their existence to color. 

Optical properties are related to both the degree of crystallinity and the actual polymer structure. Most polymers do not possess color site units, so are colorless and transparent. But, some phenolic resins and polyacetylenes are colored, translucent, or opaque. Polymers that are transparent to visible light may be colored by the addition of colorants, and some become opaque as a result of the presence of additives such as fillers, stabilizers, moisture, and gases. 

Few Chinese, Japanese, or Korean paintings on flexible supports do not use black ink to a considerable extent. Many were executed using only this medium or with slight addition of color. The virtual ubiquity of ink is undoubtedly one factor behind its importance in the Far East this is shown by the respect accorded its makers, by its treatment in Chinese historical writing, and by the extensive ink lore that exists. 

ADDITIVE COLOR PROCESS. An early system of color imagery in which the color synthesis is obtained by the addition of colors one to another in the form of light rather than as colorants. This color addition may take place (1) by the simultaneous projection of two or more (usually three) color images onto a screen, (2) by the projection of the color images in rapid succession onto a screen or (3) by viewing minutely divided juxtaposed coloi images. 

Addition of colored, fluorescent (4), or radiolabeled tags (33) to the spray formulation are useful refinements. Biological indicators, particularly sensitive plants in the case of herbicides, are also employed in many experiments 0,4). 

The object is the second part of our triad. Here we will discuss how materials interact with the energy from the light source. In this book we consider objects made of polymeric materials. Generally, polymers are colorless or at best weakly colored, and the aim always seems to be to cover up the undesirable color of the polymer in favor of the more desirable color selected by the designers. This requires the addition of colorants (pigments and dyes) to the polymer. The subject of colorants will be covered in depth in another chapter. However, because colorants become part of the object, we will first discuss some aspects of how they interact with light. 

Most neat plastic materials used for packaging of pharmaceutical products absorb UV-VIS radiation below 280 nm. Therefore, photostabilization by plastic packaging is only possible by the addition of colorants, UV absorbers, or pigments to the plastic mass. 

The endpoint may be detected by addition of colored indicators, provided the indicator itself is not electroactive. Potentiometric and spectrophotometric indication is used in acid-base and oxidation-reduction titrations. Amperometric procedures are applicable to oxidation-reduction and ion-combination reactions especially for dilute solutions. 

Some liquid oils cannot be saturated completely and a semi-solid oil is obtained. The hydrogenation process also gets rid of smelling substances from the fat or oil. Margarines are then made ready for consumption by the addition of coloring, flavoring, salt, milk and butter. 

Finally, the F. A. C. A. has set forth certain regulations of interest, regarding geographical names and additions of coloring, etc. 

The sources of dyes used by man include animal, vegetable, and mineral. Sir William Henry Perkins, in 1856, synthesized the first aniline dye. In 1860, a triphenylmethane dye, fuch-sine, was used by the French to color wine. On August 2, 1886, the U.S. Congress authorized the addition of color to butter. On June 6, 1896, Congress approved colorants in cheese, and by 1900 colorants were added to catsup, jellies, cordials, candies, sausage and noodles. However, there were some concerns by the public. For example, chrome yellow, martius yellow and quicksilver Vermillion were added to foods to hide poor quality or to increase weight. There was no control over the purity of colorants used. For example, it has been noted that rejected textile dyes were sometimes added to foods. Use of arsenic acid and mercury in the manufacture of colorants also created some concerns. 

Cosmetics. Cosmetics require the addition of colors for effec-tiveness. Colors may be added to enhance the aesthetic value, for example to after shave lotion and shampoo, or to serve a functional purpose, for example in eye brow pencil, nail polish. 

Indeed, it is the properties of the engineering resin which most likely led to its selection in the first place, so the influence of colorants on them is of utmost importance. Molders and part designers generally understand that mechanical property loss can be expected from the addition of colorants. However, problems arise when they grossly imderestimate their effect. A recent informal survey of part designers revealed that they typically plan for a 5% reduction in mechanical properties due to colorants. Depending on the resin and colorant selection, this number can easily exceed 30% Whafs more, the drive towards thinner and thinner wall sec-... 

The addition of alpha cellulose produces an unlimited range of light-stable colors and high degrees of translucency. Basic material properties are unaffected by the addition of color. 

Botch To Batch Viscosity Index Changes Batch To Batch Density Changes Addition Of Color Concentrates Moisture... 

Dispersive mixing is the process of reducing the size of a component within a polymer melt (Fig. 2.22). Consider the addition of color pigment or calcium carbonate to a polymer matrix. These additives are in particulate form and need to be reduced in size (broken up) before they can be adequately distributed throughout the matrix. Dispersive mixing breaks them up. 

Shade shM [ME, fr. OE sceadu akin to OHGr scato shadow, Gk skotos darkness] (before 12c) n. (1) In ink manufacture, commonly used as a Syn hue. (2) Term employed to describe a particular hue, or variation of a primary hue, such as a red shade blue. (3) Term used to describe the depth of color, such as a pale shade. (4) Term used to describe a mixture with black (or gray) as opposed to a tint, which is a mixture with white. (5) Verb used to describe the process of making a small modification in a color by the addition of colorant(s). See also shading and blending. 

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