Polyethylene Coated Paper: Properties, Applications, and Maintenance

What is Polyethylene Coated Paper?

Polyethylene Coated Paper (PE coated paper) is a composite material consisting of a paper substrate laminated with a thin layer of polyethylene (PE) polymer. This coating is typically applied through extrusion coating processes at temperatures ranging from 280-320°C, with coating weights varying between 12-50 g/m² depending on application requirements. The polyethylene layer, usually Low-Density Polyethylene (LDPE) with a density of 0.915-0.925 g/cm³, creates a moisture barrier with water vapor transmission rates (WVTR) as low as 5-15 g/m²/24h (at 38°C and 90% RH). The material combines the printability and rigidity of paper (typically 60-350 gsm basis weight) with the protective qualities of plastic, resulting in a versatile packaging solution.

Applications of Polyethylene Coated Paper

The unique combination of properties makes PE coated paper suitable for diverse applications:

1. Food Packaging

Dominates approximately 65% of PE coated paper usage. Common applications include:

• Fast food wrappers: Typically use 40-70 gsm paper with 12-20 g/m² LDPE coating

• Bakery papers: 60-120 gsm basis weight with dual-side coating (20-30 g/m² total)

• Liquid packaging: Multi-layer structures with 250-350 gsm paper and 30-50 g/m² PE for milk/juice cartons

• Frozen food packaging: Features cold-resistant formulations with Elmendorf tear strength >400 mN

2. Medical and Hygiene Products

• Surgical wrap: 80-120 gsm medical-grade paper with 15-25 g/m² PE coating (sterilizable at 121°C)

• Disposable bed sheets: 50-80 gsm with breathable microporous PE coatings

• Hygiene product backsheets: 30-50 gsm tissue with 8-15 g/m² PE, MVTR 500-1000 g/m²/24h

3. Industrial Applications

• Construction membranes: Heavy-duty 150-300 gsm papers with 30-50 g/m² PE, puncture resistance >20 N

• Release liners: 80-120 gsm silicone-coated over PE layer (release force 0.1-1.0 N/25mm)

• Shipping sacks: Multi-ply structures with 70-120 gsm layers, total basis weight 200-400 gsm

4. Consumer Goods

• Cup stock: 180-350 gsm with dual-side PE coating (20-40 g/m² total) for hot/cold beverage cups

• Label facestock: 60-120 gsm with 10-20 g/m² PE, dimensional stability <0.3% @ 50% RH change

• Gift wraps: Decorative papers with 10-15 g/m² PE coating for surface protection

Maintenance and Handling Guidelines

Proper care extends the functional life of PE coated paper products:

Storage Conditions

• Temperature: Maintain between 15-25°C (avoid <5°C or >40°C)

• Humidity: Store at 40-60% RH to prevent curling (dimensional change <0.5%)

• Stacking: Maximum pallet height 1.5m to prevent compression deformation

• UV protection: Shelf life reduces by 50% when exposed to >2000 lux for extended periods

Processing Recommendations

• Cutting: Use carbide blades with 25-30° edge angle at 300-500 m/min speed

• Printing: Surface treat to >38 dynes/cm for optimal ink adhesion (dyne level decays at 2-4 dynes/month)

• Heat sealing: Optimal parameters: 120-150°C, 0.2-0.5 MPa pressure, 0.5-2.0 sec dwell time

• Creasing: Rule height should be 80-90% of material thickness for clean folds

Cleaning Procedures

• Dry cleaning: Use lint-free cloths with <3% alcohol content for spot cleaning

• Wet cleaning: pH-neutral cleaners (pH 6-8) at <40°C, contact time <2 minutes

• Sterilization: Steam autoclave at 121°C for <20 minutes (for medical grades)

• Drying: Air dry at <60°C with >0.5 m/s airflow to prevent delamination

Quality Control Measures

• Coating integrity: Test for pinholes using 1% NaCl solution at 15V DC (<5 defects/m²)

• Seal strength: Measure per ASTM F88 with minimum 3N/15mm requirement

• Migration testing: Ensure compliance with EU 10/2011 for food contact materials

• Aging tests: Accelerated aging at 60°C/80% RH for 7 days simulates 1 year storage