Combatting Foam in Paper Surface Sizing: Tips and Solutions

With the continuous advancement of modern industry, paper manufacturing has become increasingly widespread. However, during the pulp and paper production process, various stages such as washing, screening, bleaching, concentration, and surface sizing are affected by foam formation to varying degrees. Today, we'll explore the origins of foam in the surface sizing process and share insights on how to effectively control it using defoamers.

What is Surface Sizing?

In the paper manufacturing process, after the sheet exits the drying section, some paper grades require further surface treatment to meet higher surface performance standards. This surface treatment generally involves steps such as surface sizing and calendering.

Surface sizing is a procedure in which a chemical coating is applied to the paper surface to form a thin film that enhances the paper's properties after drying. Surface sizing can be categorized into two methods: on-machine sizing and off-machine sizing.

Key Functions of Surface Sizing

1.Enhances Surface Properties: Surface sizing improves the paper's surface qualities, making it more durable and resistant to wear.

2.Improves Printability: By enhancing the paper's surface, it optimizes the paper's ability to absorb ink, leading to better print quality.

3.Reduces Two-Sidedness: Surface sizing helps balance the differences between the two sides of the paper, ensuring consistency.

4.Improves Porosity and Absorption: It refines the paper's internal structure, improving its porosity and absorption characteristics.

Additionally, surface sizing can increase the physical strength of the paper, such as improving its folding endurance and burst strength.

Why Does Foam Form During Surface Sizing?

Foam formation during the paper surface sizing process is mainly due to several factors:

Surfactants in Glue: The adhesives used in surface sizing often contain surfactants, making them prone to foaming.

Environmental Conditions: The temperature and humidity of the operating environment during glue production can influence foam formation.

Mixing Process: Improper mixing during glue production can introduce air into the adhesive, leading to foam formation.

The Dangers of Foam:

Foam during the surface sizing process can lead to uneven coating, causing some parts of the paper to absorb more ink, resulting in poor abrasion resistance. Furthermore, foam can lead to inconsistent adhesive application, where some areas may receive too little adhesive, resulting in excessive ink absorption, while others may receive too much, slowing down ink drying and causing smudging.

SIXIN Product Recommendations

SX-GENE 500 Series: This series offers excellent defoaming and anti-foaming performance with low dosage requirements, making it suitable for both dry and wet applications.

SX-LACHT 5301 Series: Known for its outstanding defoaming and anti-foaming capabilities, this series also features low viscosity and good stability, making it an ideal choice for various applications.

Effective foam control is essential for maintaining the quality and consistency of paper surface sizing. By understanding the causes of foam formation and using high-quality defoamers, such as those offered by SIXIN, you can ensure a smooth and efficient production process, leading to superior paper products.