Corrugated Board Delamination: Causes, Prevention, and Solutions

Delamination — the separation of paper layers in corrugated board — is one of the most common and costly quality problems in corrugated box production. This guide explains the causes and provides practical solutions for preventing and fixing delamination issues.

Understanding Delamination:

What Is Delamination?

Delamination occurs when the bond between paper layers fails, causing the liner to separate from the fluting medium or the layers of a multi-wall board to come apart. This can happen immediately after production or later during storage, converting, or use.

Types of Delamination:

• Wet-end delamination: Bond fails before fully curing

• Dry delamination: Separation occurs after board has dried

• Edge delamination: Separation at board edges

• Spot delamination: Localized areas of poor bonding

• Converting delamination: Separation during printing or die-cutting

Common Causes:

1. Adhesive Issues:

Insufficient Adhesive Application:

• Gap too large between glue roll and corrugating roll

• Glue dam settings incorrect

• Adhesive viscosity too low

• Glue roll worn or damaged

Poor Adhesive Quality:

• Incorrect gel point temperature

• Inadequate tack or green bond strength

• Adhesive degradation from age or contamination

• Wrong adhesive formula for paper types being used

2. Machine Settings:

Temperature Problems:

• Preheater temperature too low

• Hot plate temperature insufficient

• Uneven heat distribution across web

• Heat transfer compromised by dirty surfaces

Pressure Issues:

• Pressure roll settings incorrect

• Uneven pressure across web width

• Worn belts or pads

• Belt tension improper

Speed vs. Capacity:

• Running too fast for heat and adhesive to work

• Inadequate dwell time on hot plates

• Speed changes without corresponding adjustments

3. Paper Quality:

Moisture Content:

• Paper too dry (won't accept adhesive)

• Paper too wet (adhesive diluted)

• Moisture variation across web

• Different moisture levels between liner and medium

Surface Issues:

• Sizing or coating interfering with adhesive penetration

• Contamination on paper surface

• Recycled fiber content affecting porosity

Prevention Strategies:

Adhesive Management:

• Maintain correct viscosity (check regularly with cup)

• Keep gel temperature consistent and appropriate

• Use fresh adhesive (don't let it degrade in tank)

• Match adhesive formula to paper types

• Consider alkali-free adhesive for better consistency

Machine Setup:

• Regular temperature calibration and verification

• Consistent pressure roll settings

• Proper belt maintenance and tension

• Clean heat transfer surfaces regularly

• Establish standard operating procedures for each board type

Paper Handling:

• Control paper storage conditions

• Allow paper to acclimate before use

• Monitor and record paper moisture content

• Work with paper suppliers on consistency

Testing and Quality Control:

• Pin adhesion test (PAT) for immediate bond check

• Ply bond test for cured board strength

• Regular adhesive testing

• Document settings and results for reference

Solutions for Existing Problems:

Immediate Steps:

• Check and adjust adhesive viscosity

• Verify temperatures at all heat sources

• Inspect glue application pattern

• Review recent changes to materials or settings

Systematic Approach:

• Test one variable at a time

• Document changes and results

• Check paper supplier consistency

• Evaluate adhesive performance

When to Consider Adhesive Change:

If delamination persists despite machine adjustments, the adhesive formula may need revision. Xuegong's alkali-free adhesive products are engineered for consistent bond strength and easier process control. Contact our technical team for adhesive evaluation and recommendations.