Paper Machine Sizing and Coating Issues

The surface treatment stage of a paper machine presents specific quality challenges. Uneven sizing performance is often caused by size agent precipitation, hydrolysis, or poor mixing, resulting in variable water resistance and poor print quality. In coated paper production, various coating defects such as streaks, orange peel texture, or pinholes can appear, marring the paper’s appearance. After coating, the sheet requires immediate and controlled drying; insufficient drying leads to the wet coating sticking to guide rolls, a defect known as “pick-off” or “offsetting,” which ruins the sheet surface.

Solving these issues requires a comprehensive and precise approach. First, ensure strict control over the size preparation and application system, including maintaining optimal temperature and pH to prevent hydrolysis, and using effective agitation and automated dosing for consistent mixture. Second, for coating, it is crucial to maintain the precise viscosity and solid content of the coating color, and ensure the coating head (e.g., blade, roll) is clean, properly aligned, and in good mechanical condition. Third, immediately after the coating unit, implement a precisely zoned infrared or air-float dryer to rapidly set the coating without over-drying the base sheet, preventing both pick-off and curling.

Our surface treatment systems are engineered to deliver uniformity and reliability. We provide advanced size presses and film applicators with precise metering rods or blades and automated, temperature-controlled circulation systems to ensure consistent size/coating application. Our coating preparation and delivery systems feature high-sheer mixers and continuous filtration to eliminate agglomerates and air bubbles that cause defects. Most importantly, we integrate optimized drying solutions, such as efficient infrared pre-dryers followed by zoned air-float dryers, which provide rapid, gentle, and controllable drying to set the coating perfectly without causing offsetting or negatively affecting the sheet.

Our technology is designed to eliminate common defects, ensure uniform application, and optimize the drying process for maximum efficiency and product value. Stop letting surface treatment issues compromise your paper’s performance. Contact our application experts today for a consultation. Let us analyze your process and recommend the right equipment to solve your sizing and coating challenges. Email leizhanworld@gmail.com.