1、 Printing production method
1. Substrate selection
Outer layer material:
PET (polyester): High strength, friction resistant, suitable for color printing.
BOPP (biaxially oriented polypropylene): moisture-proof and transparent, commonly used in transparent window design.
Middle layer:
Aluminum foil (AL): blocks oxygen, light, and moisture, extending shelf life (commonly used in high-end grains).
EVOH (ethylene vinyl alcohol copolymer): high barrier properties but high cost, an environmentally friendly alternative to aluminum foil.
Inner layer material:
PE (polyethylene): It has good heat sealing properties and must comply with FDA/GB standards when in direct contact with food.
CPP (Cast Polypropylene): High temperature resistant, suitable for high-temperature sterilization packaging.
2. Printing process
gravure:
High precision, color saturation, suitable for mass production (with significant cost advantages over 100000 prints).
When using solvent based ink, it should be thoroughly dried to avoid residue (benzene solvents should be ≤ 5mg/m ²).
Flexographic printing:
Environmentally friendly water-based ink, suitable for short to medium length orders, but with slightly lower color levels than gravure printing.
Digital printing:
Small batch customization (such as pet portrait customization bags), no plate making fee but high unit price.
3. Composite process
Dry composite: Use adhesive to bond multiple layers of materials, requiring curing for 48 hours (VOCs emissions need to be treated).
Solvent free composite: environmentally friendly but with high equipment costs, gradually becoming a trend (recommended by the EU REACH regulation).
Co extruded blown film: a multi-layer structure extruded at once, with low cost but weak barrier properties.
4. Bag making and post-processing
Three sided sealing bag: a common standard bag type with high production efficiency.
Self standing bag: with support bars at the bottom for easy shelf display.
Zipper/easy to tear opening: enhances user experience (requires testing opening force ≤ 15N).
2、 Core Features
1. Functional requirements
Barrier properties:
Oxygen permeability ≤ 5cm ³/m ² · 24h (anti spoilage), water vapor permeability ≤ 1g/m ² · 24h (moisture-proof).
Penetration resistance:
Add a nylon layer (PA) to prevent pet teeth or freeze-dried particles from piercing.
Heat sealing strength:
≥ 35N/15mm (to avoid bag breakage during transportation).
2. Security
Food grade certification:
Compliant with FDA 21 CFR, EU 10/2011 and other regulations, heavy metal (Pb/Cd) migration amount is less than 0.01mg/kg.
Ink and glue:
Low migration UV ink or benzene free ink, adhesive tested according to GB 9685.
3. Design Features
High color difference requirement:
Δ E ≤ 3.0 (brand color consistency) to avoid differences between batches.
Surface treatment:
Covering with matte film (scratch resistant) or localized UV (highlighting logo).
3、 Industry Trends
Sustainable packaging:
Recyclable structure (such as PE/PP single material), biodegradable film (PLA).
Smart tags:
QR code traceability of raw materials, temperature sensitive ink displays freshness.
Lightweight:
Thinning the aluminum foil layer (from 7 μ m to 5 μ m) reduces costs.
