Precipitated silica has wide and important applications in the field of coatings and inks.  Thanks to its high specific surface area, excellent dispersibility, thickening properties, and optical characteristics, it has become a key additive for improving product performance.
I. Applications of Precipitated Silica in Coatings
1. Improving the Rheological Properties of Coatings
Precipitated silica, as a highly efficient rheological thickener, can significantly increase the viscosity of coatings, improve their sag resistance, and reduce dripping and running during application.
In a static state, precipitated silica forms a three-dimensional network structure through hydrogen bonding, increasing the system viscosity; when subjected to mechanical force, the hydrogen bonds break, and the viscosity decreases. This thixotropic property makes the coating easy to apply and allows it to maintain its shape after application.
The addition amount is usually controlled between 1% and 4% to obtain suitable thixotropy, avoiding excessive addition which can lead to an overly rigid system.
2. Enhancing the Covering Power and Adhesion of Coatings
The high specific surface area and micron-sized particles of precipitated silica increase the filling capacity of coatings, significantly improving covering power.
Its surface activity and adhesion properties make the coating more firmly bonded to the substrate after curing, improving adhesion and extending the service life of the coating.
In applications such as interior and exterior wall paints, automotive paints, and wood coatings, precipitated silica can effectively improve the adhesion and covering power of the paint film, and enhance the weather resistance and stain resistance of the coating.
3. Enhancing the Durability and Functionality of Coatings
Precipitated silica can improve the wear resistance, scratch resistance, and weather resistance of coatings, allowing the paint to maintain excellent performance in harsh environments.
As a matting agent, precipitated silica migrates to the surface during film formation, producing the desired roughness and significantly reducing surface gloss.
Its ultraviolet light absorption and infrared reflection properties can improve the UV shielding of the paint film. At a 3% addition rate, the UVA (320-400nm) shielding rate reaches 88%, and the UVB (290-320nm) shielding rate reaches 85%, significantly extending the artificial accelerated weathering time. 4. Adjusting the Optical Properties of Coatings
Silica nanoparticles, with particle sizes far smaller than the wavelength of visible light, possess superior optical effects. By adjusting the amount and dispersion of silica, the light transmittance, reflectivity, and transparency of coatings can be controlled.
In the preparation of high-gloss coatings, silica can provide a brighter gloss effect while maintaining the transparency of the coating.

II. Applications of Silica in the Ink Field
1. Enhancing the Color and Opacity of Ink
Silica has extremely high opacity and refractive index, effectively covering the substrate color and improving the color saturation and whiteness of printed materials.
Adding silica to ink increases the viscosity and blackness of the ink, improving the quality and gloss of printed materials, making them clearer and more delicate.
It is especially suitable for printing on light-colored substrates, effectively improving the texture and effect of printed materials.
2. Improving the Rheology and Stability of Ink
Silica can adjust the viscosity and fluidity of ink, improving the stability and printing performance of the ink.
It forms a network structure in the ink, improving rheological properties, reducing splashing, and achieving a more uniform and clear printing effect.
As a dispersant and flow control agent, silica allows pigment particles to be evenly distributed in the matrix, improving the color stability and brightness of the product.
3. Enhancing the Durability and Functionality of Ink
The high specific surface area and surface treatment capabilities of silica allow it to form a protective film structure in the ink, blocking moisture and UV erosion, extending the service life of printed materials.
In UV inks, silica can improve the light resistance and scratch resistance of the ink, adapting to the rapid curing characteristics of UV inks.
As a thickening and transparent agent, silica increases viscosity while maintaining the transparency of the ink, especially suitable for high-quality printing needs.
4. Application Characteristics in Different Types of Ink
Water-based inks: Silica improves fluidity, dispersibility, and stability, especially suitable for paper printing.
Solvent-based inks: Primarily enhances opacity and light resistance, improving texture and pattern clarity.
UV inks: As a temperature-resistant additive, it improves light resistance and scratch resistance. Letterpress Printing Ink: Enhances the brightness and whiteness of printed materials, increases color depth, and improves print quality and ink layer uniformity.

III. Application Precautions
1. Dosage Control
The amount of precipitated silica added must be strictly controlled. Too much will lead to excessive thixotropy in the system, affecting dispersion efficiency; too little will not achieve the desired effect.
In coatings, the addition amount generally does not exceed 1%; in special cases, such as zinc-rich paints requiring 2%, other rheological additives should be used in conjunction.
In inks, the addition amount is usually controlled between 10% and 30%, and needs to be adjusted according to specific requirements.
2. Dispersion Technology
Precipitated silica has a large specific surface area and high surface energy, making it prone to agglomeration.  Optimal results can only be achieved through proper dispersion.
It is recommended to first disperse the precipitated silica into a pre-slurry, and then add it to the powder dispersion.  The best results are obtained with a solvent:precipitated silica ratio of 100:9-12, dispersed at a linear speed of 22 meters/second for 15 minutes.
The use of surface modifiers, thickeners, and dispersants can improve the compatibility of precipitated silica with the matrix.