Polycoated Paperboard Boxes: Surface Treatment for Improved Adhesion
Polycoated paperboard can provide useful grease and oil resistance for food packaging, but the coated surface can also create adhesion challenges. Surface treatment helps raise surface energy so inks, coatings and adhesives can wet out and bond more reliably.
For coated folding carton programs, surface energy should be treated as a production variable. Dyne level, coating type, treatment timing, storage conditions, ink system and adhesive choice all affect whether the carton can be printed, glued and converted reliably.
Polycoated SBS and CRB can be used for grease-resistant folding cartons, but surface treatment and timing affect printability and gluability.
Corona treatment helps improve adhesion on low-energy coated surfaces
A PE coating can make paperboard more resistant to grease and oil, but it can also make the surface chemically inert and less receptive to ink, coating and adhesive bonding.
Dyne level is the key surface characteristic to monitor on polycoated paperboard
Surface tension is the property of a liquid caused by unbalanced molecular forces at or near the surface. If the liquid’s surface tension is higher than the surface energy of the material, the liquid tends to form droplets rather than spread across the surface.
In packaging production, low film surface energy can affect printability, sealability and gluability. Surface energy is commonly measured in dynes per centimeter. A higher dyne level generally indicates better wetting and adhesion potential for printing, coating and bonding.3
For polycoated paperboard boxes, the dyne level of the coated material should be reviewed before the carton is printed, coated, glued or laminated.
Liquid spread
If the surface energy is too low, liquid can bead instead of spreading evenly across the coated paperboard.
Ink receptivity
Surface treatment improves the ability of inks and coatings to wet and adhere to polycoated surfaces.
Adhesive bonding
Treated surfaces are more receptive to adhesive bonding, improving folding carton converting reliability.
Treatment decay
Surface energy can decline over time after treatment, so material age and storage conditions matter.
PE-coated SBS and CRB are often used where grease and oil resistance matter
Polycoated SBS or CRB are used in folding carton applications primarily when oil and grease resistance is required. A common application is paperboard packaging for greasy food products.
The polyethylene coating helps prevent staining and acts as a grease and oil barrier. That barrier performance is useful, but the same coating can make the surface less receptive to inks, coatings and adhesives.
To glue or print PE-coated paperboard properly, surface treatment is often required. Corona treatment is used to raise surface energy and improve the wettability and adhesion of inks, coatings and adhesives.
PE coating can support
- 1Grease and oil resistance for food packaging.
- 2Reduced staining on paperboard surfaces.
- 3Barrier performance for certain folding carton applications.
- 4Compatibility with coated SBS and CRB structures.
- 5Additional surface-treatment requirements before converting.
Grease-resistant paperboard can be useful for food packaging, but treatment and converting requirements must be planned before production.
Barrier function and converting performance have to be considered together
A coating may improve grease resistance while making printing and gluing more demanding. The carton specification should account for both needs.
Corona treatment increases surface energy so inks and adhesives can bond more effectively
Polycoated film on top of paperboard can create a chemically inert, non-porous surface with low surface tension. That makes the surface less receptive to bonding with printing inks, coatings and adhesives.
A corona treating system is designed to increase the surface energy of coated SBS or CRB so the material has improved wettability and adhesion. Treated materials can show improved printing, coating quality and lamination strength.1,2
Surface treatment is therefore not a cosmetic production step. It is part of the technical foundation that allows a grease-resistant carton to be printed, glued and converted reliably.
Treatment helps improve
- 1Ink wetting and print receptivity.
- 2Glue spreading and adhesive bonding.
- 3Coating acceptance and surface uniformity.
- 4Lamination strength where applicable.
- 5Converting consistency for coated folding cartons.
Surface energy can decline after treatment, so timing and storage matter
Polycoated paperboard can show a decline in surface energy after surface treatment. The useful shelf life of pre-treated material depends on the coating, formulation, treatment method, storage conditions and exposure to elevated temperature after treatment.2
Material purity is also important. Low molecular weight components such as antiblock agents, mould release agents and antistatic additives can migrate to the surface over time, reducing adhesion performance.
For this reason, it is generally best to print, coat or bond to treated material soon after treatment. Once the treated surface has been interfaced with a coating, ink, adhesive or another material, the bond becomes stable.
Specify dyne level, supplier certification and treatment timing before production
For polycoated paperboard boxes, the surface energy of the polycoated paper should be high enough to support the required gluing and printing performance.
A practical production specification should require suppliers of polycoated SBS or CRB to certify the dyne level with a certificate of analysis. The original guidance recommended a dyne level higher than 50, preferably in the 54 to 56 range, and recommended using corona-treated material within three months.
The final specification should still be confirmed against the coating, adhesive, ink system, converting method, storage conditions and production timeline for the specific packaging program.
Confirm with suppliers
- 1Polycoated SBS or CRB grade and coating details.
- 2Certificate of analysis showing dyne level.
- 3Treatment date and expected treatment decay window.
- 4Ink, coating and adhesive compatibility.
- 5Storage conditions before printing, gluing or bonding.
Discuss polycoated folding carton requirements with our team
Send us your product category, grease-resistance needs, paperboard preference, coating details, ink and adhesive requirements, target dyne level, artwork status, quantities and production timeline. Our team can help review structure, material selection, prepress, printing, gluing, finishing and quality requirements before launch.
Sources
- Enercon, Corona, Plasma and Flame Surface Treating. https://www.enerconind.com/web-treating/corona-treaters/
- Vetaphone, Understand Corona Treatment. https://www.vetaphone.com/knowledge-hub/understand-corona-treatment/
- Tantec, Dyne Test and Surface Energy Measurement. https://tantec.com/dyne-test-measuring-surface-energy/
- Tantec, Adhesion and Surface Treatment of Plastic. https://tantec.com/adhesion-and-surface-treatment-of-plastic/
Continue planning coated and food-grade folding carton programs
These Netpak resources connect paperboard selection, structure, prepress, quality controls and folding carton production planning.
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Open product pagePaperboard grades
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Quality and certifications
Review quality systems, traceability, certification context and production control.
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