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Requirements for Colorants in Printing Inks

Printing ink represents a primary application area for organic pigments. In developed markets, organic pigments utilized in printing inksconstitute approximately 50%-60% of their total production. With advancements in printing technology and the growing consumption of cultural goods, the performance demands for organic pigments have become increasingly stringent. Organic pigments intended for use as printing ink colorants must exhibit the following key application characteristics:

● Spectral Characteristics: The pigments for the primary complementary colors—yellow, magenta, and cyan (Y, M, C)—should meet printing specifications with minimal undesirable spectral absorption to ensure accurate color reproduction.

● Color Quality: Pigments should deliver vibrant colors with high color saturation, superior tinting strength, and enhanced gloss.

● Transparency: For four-color printing, yellow pigments in particular must exhibit excellent transparency to meet the requirements of high-quality color reproduction.

● Printing Suitability: Pigments must support optimal printing performance, including proper ink fluidity, transfer properties, plastic viscosity, and thixotropy.

● Dispersibility and Compatibility: Pigments should be compatible with ink binders, exhibit fine particle size, and demonstrate excellent dispersibility to ensure efficient ink milling and production.

● Solvent Resistance: For solvent-based inks, pigments should possess strong solvent resistance, maintain color stability, and avoid contributing to viscosity increases in the ink formulation.

● Heat Stability: For applications such as metal decorating inks, pigments should withstand heat treatments of up to 170°C without undergoing color changes or degradation.

This comprehensive set of requirements ensures that organic pigments can meet the performance, stability, and quality demands of modern printing processes.

Varieties of organic pigments for inks

The organic pigment types utilized in conventional offset printing inks have been refined through extensive practical evaluation over time, with little change in their fundamental structural varieties. The focus has shifted to enhancing their intrinsic quality and developing specialized formulations with tailored application properties through surface modification techniques. The commonly used pigment categories can be summarized as follows:

Yellow and orange spectrum: C. I. Pigment Yellow 12, C. 1. Pigment Yellow 13, C. I. Pigment Yellow 14, C. I. Pigment Yellow 74, C.I. Pigment Yellow 81, C.I. Pigment Yellow 83; C.I. Pigment Orange 5, C.I. Pigment Orange 13, etc.

Red spectrum: C. I. Pigment Red 48:1, C. I. Pigment Red 49:1, C. I. Pigment Red 53: 1, Pigment Red 57:1, etc.

Blue spectrum: C.I. Pigment Blue 15: 1, C.I, Pigment Blue 15:3, C. I. Pigment Blue 15: 4, C. I. Pigment Blue 61, etc.