How Wax Emulsion Prevents Blocking in Packaging Coatings

Wax emulsions offer excellent anti-blocking properties in packaging coatings, improving stacking performance and surface protection. See how they work and how to use them.

In flexible and rigid packaging applications, one of the most common surface defects is blocking—the unwanted adhesion between coated surfaces when stacked, wound, or pressed together. This not only affects appearance and usability but can also lead to production delays and product rejection.

One highly effective solution is the use of wax emulsions in the packaging coating formulation. In this article, we’ll explore how wax emulsions function to reduce blocking, what types are suitable, and how to apply them for maximum performance.

What Is Blocking in Packaging Coatings?

Blocking refers to the sticking together of two coated surfaces under pressure, heat, or humidity. It often occurs in:

• Printed or coated films during roll storage

• Laminates during post-processing

• Stacked cartons or pouches

The main cause is surface tackiness or insufficient surface slip after drying or curing. Blocking leads to tearing, wrinkling, or ink transfer.

How Wax Emulsion Prevents Blocking

Wax emulsions—typically based on polyethylene (PE), polypropylene (PP), or carnauba wax—are finely dispersed in water and easily added to waterborne or solvent-based coating systems.

They prevent blocking in several ways:

1. Surface Migration and Slip Creation
Wax particles migrate to the surface during film formation, forming a microscopic lubricating layer that reduces friction and tack between adjacent surfaces.

2. Surface Energy Reduction
Wax has low surface energy, meaning that less force is needed to separate touching surfaces. This reduces the likelihood of sticking under heat or pressure.

3. Film Hardness and Micro-Texture
The addition of wax modifies the micro-topography of the coating, making the surface slightly rougher at the microscopic level—helping reduce full contact and adhesion between films or sheets.

Packaging Applications That Require Anti-Blocking

Wax emulsion is ideal for:

• BOPP, PET, PE films with overprint or lacquer coatings

• Flexible packaging laminates (food and pharma)

• Carton board coatings

• Blister packs and pouch finishes

• Release coatings for labels or tapes

It can be used in both in-line and offline coating systems, and works well with other additives like anti-slip or anti-static agents.

Formulation and Processing Tips

• Dosage: 0.5%–2.0% (on total coating solids)

• Add in the letdown phase, or post-emulsify into the finished coating

• Choose non-ionic or anionic emulsions based on coating binder compatibility

• Particle size:

  • <1μm for high-gloss systems

  • 1–3μm for matte or slip surfaces

• Drying temperature: allow full film coalescence to lock in surface wax layer

Comparison: Wax Emulsion vs. Silicone Additives

Wax emulsions are often preferred in print-receptive or food-contact coatings.

Wax emulsions offer an efficient, economical, and eco-friendly solution to blocking problems in packaging coatings. By improving slip, reducing tack, and ensuring surface stability, they help ensure product quality during storage, handling, and shipping.

Want to eliminate blocking in your packaging coatings? Contact us today to request tailored wax emulsion samples and technical formulation advice.