Coatings, color evaluation

For coatings, common evaluations are in regard to surface quality, chemical resistance, color, and weathering/light stability (discussed below). Gloss and... 

A coloring pigment is used to provide the coating color, usually white, blue, grey or yellow. The selected color does not influence the material performance however, it is a useful tool in order to evaluate the application coverage and the achieved thickness. 

The need to paint the blends has also resulted in new painting systems. Recently, a nonpolar color coat based on a hydrogenated polybutadiene diol and melamine resin for TPO bumper fascia was invented. The breakthrough technology allows the elimination of the TPO pretreatment step such as adhesion promoter, flame, or plasma during manufacturing. The paintability of two different types of E-plastomers was evaluated. The olefinic white paint was found to provide excellent paint adhesion for both types of metallocene plastomers. Paint peeling was not observed in any of the test... 

Nevertheless, where it is difficult for a computer to learn expert system rules, the traditional expert system still has a place. A typical recent example of the use of expert systems is provided by the work of Dobrzanski and Madejski62 who have developed a prototype system for determining metal coating that provides an optimum combination of appearance, abrasion resistance, color, and other factors. A less scientific, but still intriguing, example of the use of these systems is HuskEval, an expert system for evaluating the quality of Siberian Huskies.63... 

Full Shade. Full-shade systems are media that contain only a single pigment. The color of the full-shade system in an optically infinitely thick (opaque) coating is referred to as full shade. The mass tone denotes the color obtained when the pigmented medium is applied as a layer that does not hide the substrate completely (e.g., on a white substrate). Evaluation can be carried out visually or by color measurement. For standards, see Table 1 ( Color in full-shade systems ). Apparatus spectrophotometer or tristimulus colorimeter. 

Transparency. Transparency is expressed quantitatively as the transparency number. This is defined as the reciprocal of the increase in color difference AE b on a black substrate obtained on increasing the film thickness h of the pigmented medium. The transparency number has the unit mm ( = L/m2). It indicates the number of liters of pigmented medium needed to coat 1 m2 of a black substrate in order to obtain a color difference of AE%b = 1 relative to this substrate. In a simplified method the transparency number can be determined by evaluating one or two points on the straight part of the AE b(h) curve. A computer method is more exact, furthermore calculations can be made using the spectral principle of spectral evaluation (see above). For standards, see Table 1 ( Transparency ). 

Weathering is the ability of the colored system, i.e., the coating, paint, etc., not the pigment alone, to resist light and environmental conditions. Changes in color and gloss aie two main factors that are evaluated in weathering tests. 

In accordance with the test specifications, the area of char is that portion which shows definite decomposition or shrinkage, and is black to dark brown in color. However, the extent of the charred area is not always clearly distinguishable and this leads to variable reporting of the same charred area. The Class F fire test has been very useful in mill control work, permitting quick evaluation of mill surface coatings. 

A potential application (not demonstrated in this study) of these HT tools and methods is to create and analyze the impact property modifying additive types and concentrations have on the performance attributes of coatings, i.e., modulus, color, and fire resistance. Specifically, one could evaluate a matrix of multiadditive packages on the intumenscence behavior of a coating intended for a steel beam. 

If proprietary mixtures (colorants, coating mixtures, flavors, controlled release matrices, imprinting inks) are used as components, information on their compositions should be provided. Any alternates that have been evaluated and determined to be interchangeable also may be included. The sponsor should be prepared either to delete the alternative from the application or to generate fur-... 

The results indicate that Sudan black penetrated into the bulk phase of lens. The dye permeation test of LBL-coated lens in wet conditions did not show stain. However, when a thin layer of liquid water exists on the surface, the dye test losses validity in terms of evaluating the barrier property of the coating because the oil spreads on the water layer, which acts as a barrier to oil-soluble dye. Wet uncoated lens did show the dye stain, which probably indicates that water on uncoated lens is not as strongly held by the surface as LBL-coated surface. The dye permeation test of LBL-coated lenses under blotted and dried conditions showed stain. The stain in blotted sample was spotty and the color intensity is less than that for the dried surface, which is more intense than that for uncoated lens, i.e., dried LBL-coated lens has the strongest dye absorption. 

Investigations, related to the photoprotection of nifedipine tablets using films containing titanium dioxide and/or tartrazine, revealed that the photoprotective effect of a film could be evaluated by using its concentration of colorant (C) and thickness (L) value. This value is the product of concentration of the colorant C and the film thickness L. Tablets coated with films having the same CL value had the same photodegradation rates. Degradation rates were found to be proportional to the CL value for every colorant system tested (18). 

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