Flexible Material Knowledge

Information from single-layer to multi-layer packaging structures.

Overview of the Material System

Flexible packaging materials fall into two groups: monolayer films and laminates. Monolayers are the building blocks; laminating different materials together yields better all-round performance for a wide range of products.

📄Monolayer Materials

Films used on their own, each with distinctive physical and chemical properties — the base layers of laminates.

BOPP (Biaxially Oriented Polypropylene)

PET (Polyester)

CPP (Cast Polypropylene)

PE (Polyethylene)

NY (Nylon)

AL (Aluminum Foil)

PVDC (Polyvinylidene Chloride)

PVC (Polyvinyl Chloride)

🔗Laminates

Two or more layers bonded with adhesive, combining the strengths of each layer.

Two-layer laminate:BOPP/CPP, PET/PE

Three-layer laminate:PET/AL/PE, BOPP/AL/CPP

Multilayer laminate:PET/NY/AL/PE (4 layers)

Monolayer Materials in Detail

📄

BOPP — Biaxially Oriented Polypropylene

Biaxially Oriented Polypropylene

Key Properties:

High clarity with good gloss
Good stiffness and excellent printability
Moderate moisture barrier
Poor cold resistance (becomes brittle at -10°C)
Low cost and very widely used

Typical Specs:

Thickness: 15-50 μm
Width: 200-2000 mm
Common: 20 μm, 25 μm

Surface Treatments:

Corona treatment (improves printability)
Metallizing (improves barrier)

Typical Uses:

Biscuit and confectionery wraps
Flower and gift wrapping
Tape substrate
Print layer of laminates

💎

PET — Polyester Film

Polyethylene Terephthalate

Key Properties:

High mechanical strength, puncture resistant
Heat resistant (up to 120-150°C)
Good gas and aroma barrier
Resists grease and chemicals
Outstanding clarity

Typical Specs:

Thickness: 12-50 μm
Common: 12 μm, 15 μm, 25 μm
Special: metallized PET, SiOx-coated PET

Price Position:

30-50% more expensive than BOPP

Typical Uses:

Retort pouches (heat resistant)
Vacuum packaging
Pharmaceutical and electronics packaging
Outer layer of premium food packaging

🧊

CPP — Cast Polypropylene

Cast Polypropylene

Key Properties:

Excellent heat sealability
Good clarity and softness
Good grease resistance
Commonly used as the inner layer of laminates
Reasonable low-temperature performance

Typical Specs:

Thickness: 25-80 μm
Common: 40 μm, 50 μm, 60 μm
Grades: standard CPP, retort CPP

Sealing Temperature:

130-160°C

Typical Uses:

Inner layer of laminate pouches (sealant)
Puffed snack packaging
Textile packaging
Inner layer of retort pouches

🥤

PE — Polyethylene

Polyethylene (LDPE/LLDPE/HDPE)

Key Properties:

Soft and tough
Low sealing temperature (110-140°C)
Excellent moisture barrier
Cold resistant (down to -40°C)
Inexpensive

PE Grades:

LDPE:Low density, soft
LLDPE:Linear low density, tough
HDPE:High density, stiff

Thickness Range:

20-200μm

Typical Uses:

Shopping bags and refuse sacks
Inner layer of frozen food packaging
Liquid packaging (stand-up pouches)
Sealant layer of laminates

🛡️

NY — Nylon (PA)

Nylon / Polyamide

Key Properties:

Very high mechanical strength
Puncture and abrasion resistant
Excellent gas barrier
Resists grease and chemicals
Relatively expensive

Typical Specs:

Thickness: 15-25 μm
Common: 15 μm
Types: NY6, NY66

Note:

Highly hygroscopic — store in a dry environment

Typical Uses:

Vacuum packaging (meat products)
Middle layer of retort pouches
Products needing a high barrier
Frozen food packaging

✨

AL — Aluminum Foil

Aluminum Foil

Key Properties:

The best barrier of all (gas, light, moisture)
100% light blocking
Dramatically extends shelf life
Opaque, with a metallic look
Fragile — must be laminated

Typical Specs:

Thickness: 7-40 μm
Common: 7 μm, 9 μm, 12 μm
Types: hard foil, soft foil

Price Position:

Expensive per kilo, but used in small amounts

Typical Uses:

Pharmaceutical blister packs
Coffee and tea packaging
Premium foods (nuts)
Military and space rations

Material Performance Comparison

Material	Oxygen Barrier	Moisture Barrier	Heat Resistance	Mechanical Strength	Clarity	Cost
BOPP	⭐⭐	⭐⭐	⭐⭐	⭐⭐⭐	⭐⭐⭐⭐	Low
PET	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	Medium
CPP	⭐⭐	⭐⭐⭐	⭐⭐⭐	⭐⭐	⭐⭐⭐⭐	Low
PE	⭐	⭐⭐⭐⭐⭐	⭐⭐	⭐⭐	⭐⭐	Low
NY	⭐⭐⭐⭐	⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐	High
AL	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐	Opaque	Medium

* The number of ⭐ indicates the performance level; ⭐⭐⭐⭐⭐ is best

Principles of Laminate Structure Design

🎨Outer Layer (Print Layer)

Function: carries the printed graphics and provides stiffness and protection

Common Materials:BOPP, PET, NY

Requirements:High clarity, good printability, high mechanical strength

🛡️Middle Layer (Barrier Layer)

Function: provides the barrier and extends shelf life

Common Materials:AL, NY, metallized film, PVDC

Requirements:Oxygen, moisture and light barrier as required

🔒Inner Layer (Sealant Layer)

Function: forms the seal and contacts the product directly

Common Materials:CPP, PE, LLDPE

Requirements:Good sealability, food safety, low-temperature performance

⚡ Design Essentials

Choose a highly printable material for the outer layer (BOPP, PET) for stiffness and appearance
Choose a high-barrier middle layer (AL, NY), balancing cost against product needs
The inner layer must be heat sealable (CPP, PE) to guarantee seal integrity
Total thickness is generally 60-150 μm, adjusted for content weight and shelf life
For frozen foods use cold-resistant materials (PE, LLDPE) to avoid low-temperature embrittlement

Common Laminate Structures and Their Uses

🍪Food Packaging

BOPP/CPP (biscuits, confectionery)

Total thickness 40-60 μm; low cost, good clarity, suits short shelf lives

PET/AL/PE (puffed snacks, nuts)

Total thickness 80-100 μm; high barrier, light blocking, 6-12 month shelf life

PET/NY/PE (frozen food)

Total thickness 80-120 μm; puncture and cold resistant, suits vacuum packing

🧃Liquid Packaging

PET/AL/NY/PE (stand-up and spouted pouches)

Total thickness 100-130 μm; a four-layer structure for juices, detergents and similar

BOPP/PE (pouched drinks)

Total thickness 60-80 μm; low cost, for short shelf life drinks

🧴Household & Personal Care

PET/PE (shampoo and body wash refills)

Total thickness 70-90 μm; moisture and corrosion resistant

PET/AL/PE (face masks, cosmetics)

Total thickness 80-100 μm; blocks light and oxygen to preserve active ingredients

💊Pharmaceutical Packaging

PVC/AL (blister packs)

PVC formed, foil lidded, one dose per cavity, moisture and light protected

PET/AL/PE (pharmaceutical sachets)

Total thickness 70-90 μm; meets pharmaceutical packaging standards with a high barrier

💡 Material Selection Guide

By Product Type

🥜 High-fat foods (nuts, crisps)

Recommended: PET/AL/PE — blocks light and oxygen to prevent rancidity

🥩 Meat and seafood

Recommended: PET/NY/PE — puncture resistant for vacuum packing

☕ Coffee and tea

Recommended: PET/AL/PE — blocks light and oxygen and retains aroma

🍬 Confectionery and biscuits

Recommended: BOPP/CPP — low cost with clear presentation

🥶 Frozen food

Recommended: PET/NY/LLDPE — cold and puncture resistant

💊 Pharmaceuticals

Recommended: PET/AL/PE or PVC blister — high barrier

By Required Shelf Life

✓

Up to 3 months: BOPP/CPP or PET/PE — low cost, suits fast-moving goods

✓

3-6 months: PET/metallized film/PE — medium barrier, good value

✓

6-12 months: PET/AL/PE or PET/NY/AL/PE — high barrier

✓

Over 12 months: PET/AL/NY/PE (four layers) — military-grade barrier

By Cost Budget

Economy

BOPP/CPP

BOPP/PE

Mid-Range

PET/CPP

PET/PE

Premium

PET/AL/PE

PET/NY/PE

🌟 Specialty Functional Materials

Metallized Film (VMPET / VMCPP)

Aluminum vacuum-deposited onto PET or CPP, combining foil-like barrier with film-like toughness

Advantages:Cheaper than foil, metallic sheen, microwave safe

Applications:Puffed snacks, biscuits, gift packaging

PVDC-Coated Film

A PVDC coating applied to a base film to raise the barrier

Advantages:Excellent oxygen barrier, transparent, moderate cost

Applications:Meat products, dairy, pharmaceuticals

Holographic Film

Carries a laser hologram for strong anti-counterfeiting

Advantages:Highly eye-catching, anti-counterfeit, premium feel

Applications:Tobacco and spirits, cosmetics, gift packaging

Easy Peel Film

Specially treated so the pack opens easily, improving the user experience

Advantages:Opens by hand — no scissors needed

Applications:Ready meals, children's food, food for older consumers

🌱 Sustainable and Biodegradable Materials

Bio-Based Materials

PLA (Polylactic Acid)

Source: corn starch, sugarcane
Compostable
Good clarity, suits food packaging
Poor heat resistance (<60°C)

PBAT (Polybutylene Adipate Terephthalate)

Soft and flexible, similar to PE
Biodegradable
Often blended with PLA
Suits shopping bags and refuse sacks

Starch-Based Materials

Modified natural starch
Fully degradable
Relatively low cost
Modest mechanical performance

Mono-Material Recyclables

All-PE Structure

PE/PE/PE co-extrusion — easy to recycle and aligned with the circular economy

All-PP Structure

PP/PP/PP structure with high recycling value, suits household and personal care packaging

⚠️ Points to Note

Biodegradable materials typically cost 2-3× conventional materials
They need industrial composting to break down effectively; degradation in nature is slow
Performance (barrier, heat resistance) generally trails conventional materials
Balance sustainability, cost and performance when choosing
Consider recyclable materials first and biodegradable materials second

Factory Direct Custom Packaging & Prototypes

Need Production Quotes or Custom Sized Boxes?

TadaPack (www.tadapack.com) offers direct factory manufacturing for corrugated shipping cartons, mailer boxes, rigid gift boxes, and eco-friendly protective packaging with instant online quotes and free vector CAD dielines.

Visit TadaPack.com