- Food Safety Compliance
Regulatory Requirements: Labels must comply with the National Food Safety Standard for General Safety Requirements of Food Contact Materials and Articles (GB 4806.1-2022). No harmful substances should migrate from the label material into the juice. For instance, solvent-based inks may contain residual benzene compounds and should be replaced with eco-friendly water-based or UV inks.
Contact Scenarios: If the label comes into direct contact with juice (e.g., inner-side bottle labels), food-grade materials such as polyethylene (PE) or polypropylene (PP) should be used. Avoid using PVC due to potential plasticizer migration.
- Environmental Durability
Resistance to Moisture and Liquid: Juice production involves washing, pasteurization, and cold chain transport. Labels must withstand water and organic acid erosion (e.g., citric acid). While regular coated paper may deform when wet, PE-laminated coated paper enhances water resistance.
Temperature Tolerance: For cold chain storage (0–4°C) or high-temperature sterilization (e.g., UHT), materials must resist thermal expansion and contraction. PET films remain stable from -40°C to 120°C, making them suitable for heat-treated products.
- Printability and Process Compatibility
Ink Adhesion: Smooth surfaces (like PE film) require corona treatment to enhance ink bonding and avoid fading or peeling. Matte surfaces (e.g., matte PP) are ideal for premium label aesthetics.
Die-cutting and Labeling Efficiency: Roll-fed labels need flexible materials to prevent fraying during cutting. In automated labeling systems, material thickness (typically 50–100μm) must be uniform to prevent jamming.
II. Main Label Material Types and Application Scenarios (Comparison Table Omitted)
III. Key Technical Considerations in Material Selection
- Water Resistance and Anti-Leak Design
Base Layer Treatment: Paper labels can be coated with waterproof layers (e.g., silicone-based) or made into tri-layer structures (paper + PE lamination + print layer). For example, a brand of NFC juice uses 300g/m² PE-laminated coated paper with 15μm lamination that resists curling after 30 minutes in cold water.
Adhesive Matching: Acrylic water-based adhesives perform better in moist environments, while modified silicone adhesives maintain stickiness at -18°C for frozen juices.
- Anti-Counterfeiting and Traceability Integration
Material-Level Security: PET films can embed fluorescent fibers or microcapsule color-changing materials for UV verification. Metallized films support holographic security features.
Traceability Carriers: Synthetic paper can hold QR codes that remain scannable after 100 rubs. RFID tags (e.g., HF tags with 0.1–1m range) may also be used, but foil-laminated materials should allow signal transmission windows.
- Eco-Friendly Material Innovations
Biodegradable Options: PLA-based PE (e.g., NatureWorks® Ingeo™) can degrade under composting conditions, though water resistance needs improvement—currently only suitable for dry label applications. Bamboo fiber paper offers high strength and renewability, replacing wood-pulp paper.
Recyclability: Single-material labels (e.g., all-PP) are easier to recycle. Multilayer labels (e.g., paper + foil) may be harder to dismantle. The EU Packaging Waste Directive mandates all packaging to be recyclable by 2030, promoting mono-material use.
IV. Special Use Case Material Solutions
- Irregular Bottles and Curved Surface Labeling
Material Selection: Ultra-thin PET (<50μm) or flexible PP adapts to curved bottles like round or oval shapes. Avoid thick board paper to prevent edge lifting.
Labeling Method: Use shrink sleeves (e.g., PVC shrink film with up to 50% shrinkage) that tightly fit after heating—commonly used for cylindrical juice bottles.
- High-Temperature Sterilization & Cold Chain
Material Challenge: UHT sterilization (135°C for 3 seconds) requires heat-resistant materials, while cold chain needs anti-brittleness at low temperatures.
Solutions: Polyimide (PI) film withstands -200°C to 260°C but is expensive. PET-G (modified PET) is a cost-effective compromise with 120°C resistance, suitable for pasteurization + cold chain.
- Children’s Products & Easy-Peel Designs
Material Selection: Low-strength synthetic PP with tear resistance of 5–8N (vs. 15N for standard PET film) makes it easy for children to open. Avoid sharp-edged materials; use rounded corners for safety.
V. Material Testing & Quality Control Procedures
- Basic Performance Tests
Water Resistance: Soak labels in 5% citric acid at 40°C for 72 hours—observe for delamination or fading.
Abrasion Resistance: Wipe label 50 times with alcohol-soaked cloth—ink should not come off. Use abrasion tester (e.g., Taber) to ensure wear loss ≤5mg.
- Labeling Adaptability Tests
Label Tension Test: On an automated labeler at 200mm/s, elongation at break should be ≥150% to avoid tearing.
Low-Temp Adhesion Test: Place labeled bottles at -10°C for 24 hours; edge peel strength must be ≥1.5N/25mm.
VI. Future Trends: Smart and Sustainable Integration
Smart Labels: Embed thermochromic inks (e.g., spirolactone dyes) that change color when juice is stored above the recommended temperature. Or use NFC chips for consumers to check production batches and temperature logs.
Recyclable Materials: Water-soluble polyvinyl alcohol (PVA) films can dissolve in water for recovery, used in some experimental juice packaging. Composite films made of plant fibers and biodegradable plastics balance strength and sustainability.
