Coated paper that fails under moisture leads to print defects, customer complaints, and wasted production. Whether you're producing coated white board, food packaging paper, or containerboard, poor surface water resistance compromises quality and profitability.
CO-04 Coating Water Repellent from Luterra Advanced Materials is a formaldehyde-free, weak cationic liquid that cross-links with starch and protein-based adhesives to deliver rapid dry and wet picking strength. This guide covers five critical mistakes to avoid when selecting and using coating water repellents.
Mistake #1: Confusing Coating Water Repellent with Internal Sizing Agent
One of the most common misconceptions is treating these two as interchangeable . Internal sizing agents (like AKD or Rosin) are added to the pulp slurry in the wet end and provide water resistance throughout the entire paper sheet . Coating water repellent, in contrast, is applied only to the surface coating layer and targets surface moisture resistance .
Internal sizing: Hydrophobicity throughout the sheet
Coating water repellent: Surface-specific protection for printing and converting
Our CO-04 Coating Water Repellent acts on the surface, forming a dense, stable film that protects against wet rub and picking during printing.
Mistake #2: Overlooking Compatibility with Coating Formulation
Not all coating systems are created equal. Adding a water repellent that is incompatible with your latex, pigments, or other additives can destabilize the entire coating color .
CO-04 is designed for neutral to weakly alkaline coating systems and demonstrates stable compatibility with latex, pigments, and functional coating additives . Its weak cationic nature allows it to work harmoniously with anionic binders commonly used in coating formulations.
Mistake #3: Using Excessively High Dosage
It's tempting to add more to get better results. However, adding too much coating water repellent can backfire significantly. Overdosing can lead to a brittle coating and reduced interlayer bonding force. In severe cases, it causes an overly slippery paper surface and poor printing ink adhesion-defects that defeat the purpose of using the repellent in the first place.
The recommended dosage for CO-04 is 0.2%–0.7% based on the oven-dry weight of pigments. Always start at the lower end and adjust based on actual paper grade and coating formulation needs.
Mistake #4: Ignoring Addition Sequence and Timing
How and when you add the water repellent affects its cross-linking efficiency. Adding it too early-before other components are properly mixed-can result in uneven distribution and poor curing.
For optimal results with CO-04:
Complete the addition of all coating adhesive components first.
Add CO-04 at a constant speed (manually or via automated system).
Stir thoroughly after addition to ensure sufficient cross-linking reaction throughout the system.
This sequence maximizes the cross-linking between CO-04 and starch/protein-based adhesives, delivering the best possible wet rub resistance.
Mistake #5: Neglecting Environmental and Regulatory Requirements
Traditional coating water repellents often contain formaldehyde or other harmful compounds that face increasing regulatory restrictions . For food packaging and other sensitive applications, choosing a product that meets safety standards is critical .
CO-04 is formaldehyde-free, making it an eco-friendly, low-toxicity option suitable for food packaging paper, containerboard, and other applications where safety is paramount . It provides peace of mind alongside performance.
CO-04 Coating Water Repellent: Product Specifications at a Glance
| Parameter | Specification |
|---|---|
| Appearance | Colorless to slight yellow transparent liquid |
| Solid content | 50±1% |
| Viscosity | ≤220 mPa·s |
| pH (2% dispersion) | 7.5–9.5 |
| Water solubility | Freely soluble |
| Ionic property | Weak cationic |
Application Scope
CO-04 adapts to the curing process of high-speed paper machines. It rapidly improves the dry and wet picking strength and wet rub resistance of coatings. It is suitable for:
Coated white board
Grey board
Food packaging paper
Containerboard
Tips for Optimal Results
Recommended dosage: 0.2%–0.7% based on oven-dry pigment weight
Addition timing: After completion of coating adhesive addition
Mixing: Stir thoroughly after addition for sufficient cross-linking
Frequently Asked Questions
Q: Will excessive addition cause production issues?
A: Yes. Overdosing may lead to brittle coating, reduced interlayer bonding force, overly slippery paper surface, and poor printing ink adhesion. Always adhere to recommended dosage ranges.
Q: What is the difference between internal sizing agent and coating water repellent?
A: Internal sizing acts on the entire paper base, while coating water repellent works only on the surface coating to targeted improve surface moisture resistance .
Q: Is this product suitable for food packaging applications?
A: Yes. CO-04 is formaldehyde-free, making it a safe choice for food packaging paper and other sensitive applications.
Ready to improve your coated paper quality?
Contact Luterra Advanced Materials for a free sample and customized compounding solutions. Our technical team can help you optimize dosage and addition methods for your specific coating formulation and production conditions. [Get Free Quote / Contact Now]
