Case and Carton Sealing
Carton sealing is the largest single application for hot melt adhesives in packaging. Every folded cardboard box that ships a product — from e-commerce parcels to consumer goods cartons — relies on hot melt adhesive applied by case sealers operating at speeds from 20 to 150 cases per minute.
Requirements: Fast set time (under 3 seconds), good fiber tear on corrugated board, adequate green strength to withstand immediate handling, and cost efficiency at high volumes.
Recommended adhesive type: EVA-based hot melts with medium-to-high viscosity (8,000–15,000 mPa·s at 177°C) and softening points of 80–90°C. For heavier cartons or those subject to warmer storage conditions, consider PO-based alternatives offering slightly better heat resistance.
Common failure mode: Insufficient adhesive applied to flaps, often caused by worn nozzles or incorrect bead pattern. Ensure regular nozzle inspection and replacement as part of preventive maintenance.
Tray Erection and Assembly
Tray-forming machines erect flat cardboard blanks into rigid trays for food products, electronics, cosmetics, and pharmaceuticals. Hot melt is applied to glue tabs and corner joints during the forming cycle.
Requirements: Moderate open time (10–20 seconds) to allow proper positioning before set, good penetration into coated and uncoated board surfaces, and clean appearance since trays are often customer-visible.
Recommended adhesive type: Lower-viscosity EVA grades (3,000–8,000 mPa·s) that wet out quickly on board surfaces. Some applications benefit from metallocene-catalyzed PO hot melts offering cleaner aesthetics on white packaging.
Flexible Packaging Lamination
Laminating films, foils, and papers together using hot melt adhesive creates multi-layer packaging structures with barrier properties, print surfaces, and structural integrity. Applications include food pouches, blister packs, and cosmetic sachets.
Requirements: Very thin, uniform bond line; clarity or translucency depending on design; food-contact compliance for many applications; and specific barrier properties against moisture, oxygen, or grease.
Recommended adhesive type: Specialized low-viscosity PO or co-polyester hot melts designed specifically for laminating applications. Food-contact grades must comply with FDA (US) or EFSA (EU) regulations. For retort pouch applications requiring sterilization resistance, high-performance PA or specialized PO formulations are necessary.
Bottle Labeling
Pressure-sensitive labels applied with hot melt PSA (pressure-sensitive adhesive) dominate the beverage and personal care industries. The hot melt is coated onto label stock during converting, then activated by pressure during application on the filling line.
Requirements: High initial tack, excellent clarity, water and condensation resistance (especially for refrigerated beverages), and consistent die-cutting performance during label conversion.
Recommended adhesive type: SBS (styrenic block copolymer) based hot melt PSAs formulated for labeling applications. Different grades are optimized for glass bottles, plastic bottles, and variable surface energy substrates.
End-of-Line Packaging
This category includes miscellaneous assembly tasks on packaging lines: attaching promotional items, securing inserts, mounting display components, and assembling point-of-sale displays.
Requirements vary widely depending on the specific task. General-purpose EVA hot melts handle most end-of-line needs economically. For applications involving plastic substrates or potential heat exposure during shipping, upgrade to PO or PA-based formulations.
Selecting Your Packaging Hot Melt: Decision Framework
- Identify substrate materials (paperboard type, coatings, film types)
- Determine line speed and required set/open time
- Check regulatory requirements (food contact, toy safety, environmental)
- Estimate annual consumption volume (affects pricing leverage)
- Request samples from 2–3 suppliers and test on your actual substrates
- Evaluate total applied cost per unit, not just adhesive price per kilogram
Remember that adhesive cost is typically less than 0.5% of total packaged product value. Saving a few cents per kilogram on inferior adhesive that causes even a 0.1% rejection rate costs far more than investing in the right material.