In modern papermaking, surface sizing agents play a pivotal role in enhancing the performance and end-use value of paper products. From improved printability to increased moisture resistance, these additives are indispensable in achieving high-quality paper suitable for demanding printing, packaging, and industrial applications.
1. What Are Surface Sizing Agents?
Surface sizing agents are chemicals applied to the surface of paper after sheet formation but before drying. They are typically added through a size press and can be starch-based, synthetic, or a combination of both. Their primary function is to modify the surface properties of paper, particularly in enhancing strength, smoothness, and resistance to liquid penetration.
Common types include:
- Starch-based sizing agents
- Alkyl ketene dimer (AKD) emulsions
- Alkenyl succinic anhydride (ASA)
- Styrene-acrylate polymer
- Fluorine-free hydrophobic coatings
2. Enhancing Paper Printability
One of the main benefits of using surface sizing agents is improved printability, especially in inkjet and offset printing.
Key Contributions:
- Ink Holdout: Surface sizing creates a controlled absorption profile, preventing ink from soaking into the paper too quickly. This leads to sharper images and crisper text.
- Surface Smoothness: Sizing helps fill in surface irregularities, ensuring even ink distribution.
- Improved Runability: A well-sized surface reduces dusting and paper lint, enhancing machine performance during high-speed printing.
Printability is especially crucial in applications such as:
- Commercial printing (brochures, flyers)
- Book and magazine production
- High-resolution label printing
3. Improving Moisture Resistance
In addition to enhancing print quality, surface sizing agents also offer excellent moisture resistance. This is particularly important for packaging papers and boards exposed to variable humidity or direct contact with liquids.
Mechanisms of Moisture Resistance:
- Hydrophobic Barriers: Sizing agents form a thin hydrophobic film on the paper surface, which acts as a moisture barrier.
- Internal and Surface Synergy: When combined with internal sizing, surface sizing enhances total water repellency and sheet integrity.
- Wettability Control: Proper sizing reduces water penetration and fiber swelling, preserving the dimensional stability of the sheet.
Moisture resistance is critical for:
- Food packaging
- Folding cartons
- Beverage cup stock
- Carrier boards
4. Hydrophobic Paper Coating: The Next Evolution
Modern surface sizing technologies now integrate hydrophobic paper coatings—advanced formulations that push the boundary of water resistance without compromising recyclability or print performance.
These coatings typically involve:
- Modified polymer dispersions
- Non-fluorinated waterproofing agents
- Crosslinking chemistries for improved film formation
Such treatments result in:
- Grease- and water-resistant surfaces
- Environmentally friendly alternatives to fluorinated coatings
- Enhanced durability for outdoor and industrial applications
5. Sustainability and Trends in Surface Sizing
With increasing regulatory and consumer pressure, fluorine-free sizing technologies are gaining ground. These new-generation surface sizing agents maintain high water and oil repellency while being safer for human health and the environment.
Additionally, the integration of bio-based and biodegradable polymers is creating opportunities for sustainable paper production without sacrificing performance.
In a competitive and evolving paper industry, surface sizing agents are essential for delivering papers with superior printability, moisture resistance, and hydrophobic properties. Whether it’s enhancing ink performance or creating a water-repellent surface for packaging applications, these functional additives are shaping the future of paper.
By selecting the right surface sizing chemistry, papermakers can optimize product performance, reduce print defects, and meet the growing demand for sustainable, high-performance paper solutions.
Need high-performance surface sizing agents for your paper applications?
Amazon Chemical specializes in customized chemical solutions for the paper industry. Our range of surface sizing agents helps improve ink holdout, reduce water penetration, and meet the evolving standards of sustainability and efficiency.
🌐 Learn more at: www.amazon-chem.cn
📩 Contact us for technical support and product samples.
