Application of surfactants in papermaking coating

The coatings used in coating processing are mainly composed of adhesives, pigments and other auxiliaries. The coating itself is a complex compound, and the corresponding formulation varies according to different paper requirements. Surfactants play an important role in the preparation of paper coatings, including dispersant, defoamer, lubricant, preservative, antistatic agent and synthetic latex.

They work in three ways: they give pigment particles an electric charge, causing them to repulse each other; Covering the surface of pigment particles to protect the colloid; A state of high viscosity is formed around the particles to prevent multiple particles from condensing.

Defoamer: Foam is often produced during the preparation and coating of coatings, so it is necessary to add defoamer. Commonly used defoamants include higher alcohols, fatty acid esters, tributyl phosphate and tripropyl phosphate.

Lubricant: In order to improve the fluidity and lubricity of paper coatings, increase adhesion, give the coating smooth and shiny, increase plasticity, prevent cracking, improve the printability of coated paper, etc., so it is necessary to add a certain lubricant. At present, the most widely used lubricants are water-soluble metal soap surfactants represented by calcium stearate, sodium stearate water-soluble lubricants also have obvious effects, paraffin hydrocarbons and fatty acid amines can also be used as lubricants.

Preservatives: Because some natural adhesives are easy to degrade and mold, preservatives need to be added to paper coatings. Commonly used preservatives include quaternary ammonium cationic surfactants, fluorinated cyclic compounds, organobromine compounds, etc.

Antistatic agents: In order to give the paper antistatic properties, you can add octadecyl trimethyl ammonium fluoride, polyoxyethylene sorbitan ester, alkylphenol polyoxyethylene ether phosphate and polystyrene sulfonate to the coating formulation. Synthetic latex is an important part of coating adhesive. In the preparation of synthetic latex, surfactant plays an important role as emulsifier, dispersant and stabilizer.