Color Shifts

Color shift is another important issue for liquid crystal displays. In an IPS mode, yellowish color shift occurs at the = 45° azimuthal angle and bluish color shift occurs at = -45° due to the phase retardation difference. To suppress color shift, a chevron-shaped electrode similar to a two-domain structure has been proposed [34,35] Each pixel is divided into two domains, where the LC directors face in opposite directions and the color shift is compensated effectively. 

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It has not been determined which hydroxyl group contains the more acidic hydrogen atom corresponding to p Dyes of this type would behave as indicators and exhibit large color shifts with the pH range normally encountered in textile processing. Hence they are always stabUized by coordination with metal ions. 

Film CAS Registry Number Growth method Possible dopants Oxidizing color shift References... 

The sohd-state, transition-metal example in Table 1 of [(CH2)2NH2]3CuCl illustrates another form of thermochromism the color shifts gradually and continuously because of changes in bandwidth with either heating or cooling (6). It is not unique, as this behavior has been mentioned for the class of... 

Fig. 6. Color-shifting dye developers (a) yeUow dye developer [16044-30-7] that becomes magenta upon hydrolysis (b) cyan dye [50695-79-9] that becomes colorless upon protonation and (c) leuco form of a dye developer [50481-86-2] that becomes yellow upon hydrolysis and oxidation.

What are the typical materials used to create the color-shifting flakes A symmetrical layering pattern of absorber/dielectric/reflector/dielectric/absorber is... 

Figure 12.7.2 Layering patterns of absorber (partially reflected)/dielectric (low re-fractive)/reflector (inner reflector)/dielectric/absorber used to create the optical effect of color-shifting ink.

Color-Shifting Ink. Unites States Treasury, http //www.bep.treas.gov/cd042500/color.html... 

A solvent-free synthesis of substituted spiroindolinonaphth[2,l-fo][l,4]oxazines through condensation of 2-methylene-l,3,3-trimethylindoline derivatives with 1-nitroso-2-naphthol under microwave irradiation has been described by Fedorova and colleagues (Scheme 6.263) [453], In a typical reaction, an equimolar mixture of the two starting materials was irradiated at 65-110 °C for 15 min to produce the desired spiroindolinonaphth[2,l-fo][l,4]oxazines, which are useful as photochromic compounds. In a related procedure, addition of morpholine to the reaction mixture led to the formation of the corresponding 6 -amino-functionalized spiroindolino-naphth[2,l-fo][l,4]oxazines, which exhibit a strong hypsochromic color shift (not shown) [453]. 

Paints behave similarly. Fig. 68 illustrates the color shifts which are observed in Pigment Yellow 1 pastes containing different particle size distributions (Sec. 1.7.1). The colors are identified according to their location on the DIN Color Chart, in which each color is defined by two values, x and y [4]. Increasing amounts of pig-... 

Considerable shearing forces will break down the particles in the variety with a coarser particle size. It is interesting to note that the tendency of a pigmented system to become hazy decreases as the dispersion time increases, accompanied by improved gloss, color shift towards more yellowish shades, enhanced color strength in white reductions, and increased viscosity [22],... 

Transparent P.O.34 is somewhat sensitive to heat and generally only withstands temperatures up to 100 to 140°C. Higher sterilization or metal deco printing temperatures may produce a color shift towards a redder orange. 

P.R.222 is heat stable up to 240°C above this temperature, the color shifts appreciably towards the bluish side of the spectrum. P.R.222 bleeds in plasticized PVC. 

Studies of the metal-exchange process of P.R.49 (Na) to P.R.49 1 (Ba) [1] revealed that the process, apart from the temperature, is not only influenced by the crystal structure and the concentration of the barium ions but also by the amount of rosin soap. Colophony-based rosin which is assumed to act as a surfactant, is converted during the laking process into colorless insoluble rosinate salts. These salts are incorporated in the pigment til up to 30% by weight without a loss of tinctorial strength. Very often the color strength is even increased, accompanied by a color shift to more bluish reds. 

Temperatures of up to 100°C and higher may be observed as P.R.57 1 is dispersed in offset printing inks, especially in web offset inks by means of modern dispersion equipment. This is especially true for agitating pearl mills. Printing inks and prints may undergo color shifts if they are exposed to these conditions. The process, which is reversible, is caused by release of the water of crystallization from the pigment. 

In white reductions, P.R.208/polyolefin systems only withstand temperatures below 200°C, while transparent specimens (0.1%) are stable up to approximately 240°C. Thus the pigment is a suitable and economical candidate for polypropylene spin dyeing, provided the temperature is kept below 200°C. It is also possible to apply higher temperatures if a color shift towards more yellowish shades is acceptable. In terms of lightfastness, P.R.208 meets the common standards for interior application. 

P.R.81 is used especially in three and four color printing and lends itself to various printing processes, therefore pigments of this type are referred to as Process Red in the USA. Used as a colorant for NC-based printing inks, SM types of P.R.81 may present problems as they are dispersed with steel balls or stored in steel containers as well as at elevated temperature. Catalytic decomposition of the binder and damage to the pigment may induce a color shift and increase the viscosity. 

We see that as spectral width is increased, the spectra have to be shifted to longer wavelengths to maintain the proper X/Y ratio, otherwise the short wavelength wing would yield an orange color shift. This has the disastrous consequence, however, of drastically reducing the values of X and Y, since the broadened, shifted spectra make increasingly poorer matches to the x and y curves. 

ZiijCdgSAg 48% 0.66 0.33 0.12 180% 112% SATURATES EASILY COLOR SHIFTS DARK BODY COLOR... 

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