Resistance to light

Resistance to light is determined for pigments dispersed in the material in which they to be used. Two methods of exposure are used under glass outdoors or in an artificial weathering unit equipped with a xenon arc as a source of radiation. The result of exposure is compared with a standard exposed to the same conditions. The evaluation is based on the color differences between the exposed and shadowed parts of the specimens. 

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When the chlorohydrine group was bonded from 2.65 to 4.9 mol% to the aromatic ring of PS, the following changes were obtained hardness increased from 175 to 228 N/mm and resistance to light increased from 1(X)°C to 150°C. When this polymer was converted to epox-ylated PS in the basic medium, the same mentioned above properties were also observed. Moreover, the stretch, breaking, and adhesion capabilities increased from 48.5-60.0 MPA and 3.8-5.3 MPA, respectively (Fig. 9 and Table 5). 

Titanium dioxide is an amorphous white powder characterized by brightness and a very high refractive index (2.4). It is insoluble in water and organic solvents, and is a very stable material, resistant to light, pH variation, oxidation, etc. Ti02 is available in oil-dispersible and water-dispersible forms. 

The paints market shows only limited interest in P.Y.55, although the pigment is occasionally used to lend color to low quality industrial paints. In 1/3 SD white reductions, the pigment matches the lightfastness of P.Y.13 samples its full shades are more lightfast. Addition of TiOz decreases its resistance to light. 

P. O.13 sample reaches only step 4. Transparent P.O.34 colorations in rigid PVC are even more resistant to light. Pigment concentrations of less than ca. 0.1% are likewise unsuitable, due to the necessity to avoid blooming. The pigment is also used in vinyl floor coverings and in cable insulations. 

EVAs are naturally resistant to light, UV, ozone and weathering and, even more, they can be protected by addition of specific anti-UV and other protective agents. Under identical... 

EVOH is sufficiently resistant to light and UV to be used in packaging. 

PVDC is currently handicapped by the ecological problems associated with chlorine, the limited number of producers, its cost, limited resistance to light and some organic chemicals such as aromatic hydrocarbons, ketones etc., impact sensitivity the more so as the temperature decreases, high density, fume toxicity and corrosivity in the event of fire. 

PCTFE is appreciated for good chemical resistance exceptional low-temperature behaviour down to -240/250°C gas barrier properties excellent resistance to light, UV and... 

Resistance to light and weather generally depends on the chemical composition, structure, defects, particle shape and size, and concentration of the pigment [1.53], However, these properties also depend on the medium in which the pigment is used. Testing is carried out by open-air weathering, accelerated weathering, and chemical test methods. 

Properties and Uses. As far as resistance to light, weather, and chemicals is concerned, transparent iron oxides behave in a similar manner to the opaque iron oxides (see Section 3.1.1). In addition, they show a high UV absorption, which is exploited in applications such as the coloring of plastic bottles and films used in the packaging of UV-sensitive foods [5.276], [5.277]. 

Transparent cobalt blue pigments have the form of small tiles (primary particle size 20-100 nm, thickness ca. 5 nm, specific surface area (BET) ca. 100 m2/g). They are resistant to light and weather and are used in metallic paint, but are of little importance. 

Pyrazolinones belong to the heterocyclic class of coupler and are widely used the sulfonamide (124) is representative of this type (51USP2537098). Substituted thiophenes (125) (58GEP1025265) and hydroxypyridones (126) (47USP2431190) are couplers which form blue-violet dyes resistant to light. Pyranones (127), analogous to the latter, have also been used (51USP2542849). 

Rh1 corrinoids show reactivity similar to the Co analogue, but the alkyl—Rh bonds are more resistant to light than the alkyl—Co bonds.264... 

Aftertreatment is not required. Raw cotton is covered well. The resistance to light is very good the disadvantages are limited depth of color, stiffer feel of the product, and limits to the rub- and wetfastness. 

Nylon 6, or nylon caprolactam, is a polymeric fiber derived from only one constituent, caprolactam, giving the polymer [-(CH2)5CONH-] . It has a lower melting point than nylon 6,6, but it is superior to it in resistance to light degradation, elastic recovery, fatigue resistance, and thermal stability. 

Red lead (Pb304) has a brilliant red-orange color, is quite resistant to light, and finds extensive use as a priming coat for structural steel because it possesses corrosion-inhibiting properties. 

Fibers of Polymer IV show a comparatively strong resistance to light degradation (Table V). These values compare favorably with the... 

Spirooxazines have excellent resistance to light-induced degradation. This property, also called fatigue resistance, is considered to be due to photochemical stability of the oxazine molecule framework in the ring-closed form as well as in the open-ring form. The fatigue resistance of the spirooxazines has led to then-successful use in various applications, for example, eyewear. 

Reaction to Pretreating. One particular method of setting fugitive colors on fabrics reported by Adams (1) was of particular interest because it involved compounds containing potassium and sulfur, both elements detected in the dress fabric x-ray analysis. As reported in that study, similar sorts of solutions were used by dyers and cleaners to increase the dye resistance to light and washing. 

Specification Lead white (see white lead Light stability (see also resistance to light) D 1648 ... 

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