Abstract: Color-stable, pigmented optical bodies comprising a single or multiple layer core having at least one layer of a thermoplastic polymer material. The thermoplastic polymer material has dispersed within it a particulate pigment. The optical bodies generally possess high clarity and low haze and exhibit a transmission of light within a wavelength band of interest within the visible spectrum of from about 10 to about 90 percent. The optical bodies also comprise one or more dyes in an amount sufficient to adjust transmitted color, by no more than about 15 units of the color coordinate a* and no more than about 15 units of the color coordinate b*, to a target color such as neutral gray.

Abstract: A method for the rapid esterification of dicarboxylic acids or the transesterification of lower alkyl carboxylic acid diesters with diols is disclosed. The method includes recycling of evaporated unreacted starting materials and can be carried out at elevated pressures. The resulting esterification or transesterification products can then be polymerized into polyesters, for example by a thin film polymerization method.