Technical Articles
Why Corrugated Board Delamination Happens
A root-cause guide to corrugated board delamination: adhesive, viscosity, heat, paper moisture, and machine settings—plus a buyer and plant troubleshooting sequence that prevents false blame.
Delamination is a system failure, not a slogan defect
When liner separates from medium, buyers often hear “bad glue” or “bad paper” within minutes. Real plants fix delamination only when they treat it as interaction among adhesive film, gelatinization, paper moisture, heat, pressure, and speed. This article gives a cause map and a sequence that stops random recipe changes.
What “delamination” looks like in the field
Edge opening after slitting; soft board that crushes in stacking; flute pull-away in die-cutting; blistering; converting jams from weak pins. Note whether failure is immediate off-line or after humidity exposure—post-shipment failures often point to moisture and ECT margin, not only glue brand.
Cause group A — adhesive and glue kitchen
Viscosity out of band; solids wrong; aged or contaminated batch; incorrect mix water temperature; wrong gel-temperature product for the heat system; starved or flooded glue film. Link closely with the viscosity Knowledge article: unstable kitchen control is the most common hidden driver.
Cause group B — paper and moisture
Medium or liner too wet or too dry; recycled furnish variation; cold paper entering the single facer; storage of reels in uncontrolled humidity. Paper that fights the glue’s water balance will not bond even with “correct” viscosity readings.
Cause group C — machine heat and mechanics
Preheaters and hot plates out of balance; wrap angles wrong; worn glue rolls; pressure insufficient; speed increased without heat/glue compensation. Many “glue claims” disappear after mechanical audits.
Cause group D — specification and procurement errors
Board construction changed without re-qualifying glue; supplier switched starch lot with no COA review; trial skipped after summer-to-winter transition; ECT raised on PO without checking bond process capability.
Troubleshooting sequence (do not skip steps)
1) Capture samples and photos with lot IDs. 2) Check today’s viscosity and mix logs. 3) Measure paper moisture if possible. 4) Verify heat setpoints vs SOP. 5) Inspect glue film and roll condition. 6) Only then change adhesive brand or paper grade. Changing two variables at once guarantees confusion.
Buyer actions when claims arrive from your carton supplier
Ask for glue lot COA, viscosity records, board construction, and whether paper lots changed. Request a joint trial plan. Do not accept “we changed to cheaper glue” without data. If you buy sheets, identify whether mill or converter owns the bond process.
Prevention in sourcing contracts
Freeze construction + adhesive grade for approved SKUs; require notification before glue or paper switches; define delamination AQL or claim evidence rules; schedule seasonal re-checks for humid destinations.
Related PackTrades Knowledge
Why Corrugating Line Glue Viscosity Fluctuates, Corrugated Board ECT and FCT Explained, How to Choose Corrugated Board Glue from China, and Adhesive Shelf Life and Storage Guide.