Most paper products rely on a coating layer to improve their appearance, printability and barrier properties. Paper coating additives are applied to the surface of printing paper or packaging board to create a smoother surface, enhance color performance and add functional protection, such as water and grease resistance, when needed.
Paper coating chemistry is typically comprised of pigments, binders and additives. Of these three main components, additives make up the least amount of the dry weight of the coating yet contribute important properties. Additives include dispersants, lubricants and insolubilizers, and their role is to enhance the overall performance of the finished coating by improving the coating’s stability, flowability and durability.
Solenis’ paper coating additives are available globally but are marketed as Nopcote™ coating additives in Europe and Asia Pacific, and as Impress™ coating additives in North America. Our family of additives help papermakers optimize the performance of their paper and packaging coatings. All of our chemistries have been developed using 100-plus years of experience in pulp and paper operations, which means you can trust our team to help you develop coating formulations that improve product quality, increase production and help you adapt to evolving regulatory and environmental demands.
A Range of Additives to Control Specific Properties
Solenis offers a complete portfolio of Impress™ and Nopcote™ coating additives to improve the performance and functionality of coatings used on paper and board. They include:
Crosslinkers / Insolubilizers
Crosslinkers, also referred to as insolubilizers, are used to improve the water resistance and durability of coated surfaces. These additives react with water-soluble components—such as starch-containing coatings—reducing solubility and helping coatings maintain integrity during converting and printing processes.
Solenis offers two distinctive crosslinker chemistries: blocked glyoxal crosslinkers, which reduce water solubility of starch-containing paper coatings without increasing reactivity or viscosity of the coating, and potassium zirconium carbonate crosslinkers, which allow uniform distribution of the binder with the coating and improves printability.
Dispersants
Dispersants are essential for maintaining stable and uniform coating formulations. They help keep pigment and mineral particles properly dispersed, preventing agglomeration that can lead to coating defects, poor coverage, or inconsistent surface appearance.
By improving coating stability and process efficiency, dispersants enable smoother machine performance and more reliable coating application during production.
Solenis’ polyacrylate-based dispersants stabilize pigment slurries, improving rheological properties, and enhance flowability of pigmented coatings.
Lubricants
Coating lubricants improve the runnability of coated board as it travels through the paper machine and comes into contact with various surfaces. By reducing friction and surface wear, lubricants help minimize defects, improve operational efficiency, and support higher-quality coated output. These solutions contribute to improved surface performance and enhanced print results once the board reaches end-use applications.
Our calcium stearate lubricants require no predispersion and may be mixed directly with the coating color. They improve the flow and leveling characteristics in starch, protein or latex coatings.
Wax Dispersions
Wax dispersions provide additional surface functionality and performance enhancement for specialty coating applications. As hydrophobic agents, these dispersions of wax can be incorporated into coatings to make them more effective at repelling water, oil and other types of contamination.
Application of Additives
In practice, papermakers introduce coating additives so each additive can interact with pigments and binders effectively while maintaining stable rheology and good machine runnability. Solenis’ paper coating additives are typically introduced during preparation of the coating formulation in the coating kitchen, just before the coating is applied on the paper machine. A typical sequence would follow these steps:
- Pigment slurry is first prepared and diluted
- Binder is prepared separately and then blended into the pigment slurry
- Coating additives are dosed into the coating color tank
Solenis field professionals can help mills determine where and when to add Impress™ and Nopcote™ additives based on formulation chemistries and the desired properties of the final coated product.
More Information
If you would like to learn more about Impress™ or Nopcote™ coating additives, talk to a Solenis expert today.
