Complete guide to packaging bag structures, packaging upgrades rely on it!

As the saying goes, "clothes make the man." Good packaging can greatly enhance consumer memory, attention, and focus. Therefore, products with exquisite, unique, and more functional packaging are a business strategy, a tool for brands to become industry leaders in fierce market competition, and a key element in brand strategy.

Below, Shunxingyuan Packaging, a professional flexible packaging manufacturer, combines common packaging structure knowledge to provide a reference for companies to upgrade their product packaging.

 

 

 

 

1. Steaming and boiling packaging bags

Packaging requirements:

Used for packaging meat and poultry, requiring good barrier properties, resistance to puncture from bones, and no breakage, cracking, shrinkage, or odor under steaming and boiling conditions.

 

 

 

 

Design structure:

Transparent type:

BOPA/CPP, PET/CPP, PET/BOPA/CPP, BOPA/PVDC/CPP

PET/PVDC/CPP, GL-PET/BOPA/CPP

Aluminum foil type:

PET/AL/CPP, PA/AL/CPP

PET/PA/AL/CPP, PET/AL/PA/CPP

Design rationale:

PET:

High temperature resistance, good rigidity, good printability, high strength.

PA:

High temperature resistance, high strength, flexibility, good barrier properties, puncture resistance.

AL:

Best barrier properties, high temperature resistance.

CPP:

High-temperature resistant, good heat sealing, non-toxic and odorless.

PVDC:

High-temperature resistant barrier material.

GL-PET:

Ceramic vapor-deposited film, good barrier properties, microwave transparent.

For specific products, choose the appropriate structure. Transparent bags are mostly used for steaming and boiling, while AL foil bags can be used for ultra-high temperature steaming and boiling.

2. Puffed snacks

Packaging requirements:

Oxygen barrier, water barrier, light protection, oil resistance, aroma retention, crisp appearance, bright colors, low cost.

 

 

 

 

Design structure:

BOPP/VMCPP

Design rationale:

Both BOPP and VMCPP are crisp. BOPP has good printability and high gloss. VMCPP has good barrier properties and aroma and moisture retention. CPP also has good oil resistance.

3. Soybean paste packaging bags

Packaging requirements:

Odorless, low-temperature sealing, anti-sealing contamination, good barrier properties, moderate price.

Design structure:

KPA/S-PE

Design rationale:

KPA has excellent barrier properties and high toughness, high bonding strength with PE, not easily broken, and good printability. Modified PE is a mixture of various PEs (co-extrusion), with a low heat sealing temperature and strong anti-sealing contamination.

4. Biscuit packaging

Packaging requirements:

Good barrier properties, strong light shielding, oil resistance, high strength, odorless, crisp packaging.

 

 

 

 

Design structure:

BOPP/EXPE/VMPET/EXPE/S-CPP

Design rationale:

BOPP has good rigidity, good printability, and low cost.

VMPET has good barrier properties, light shielding, oxygen barrier, and water barrier.

S-CPP has good low-temperature heat sealing and oil resistance.

5. Milk powder packaging

Packaging requirements:

Long shelf life, aroma and flavor retention, prevention of oxidation and deterioration, and prevention of moisture absorption and caking.

 

 

 

 

Design structure:

BOPP/VMPET/S-PE

Design rationale:

BOPP has good printability, gloss, and strength, and a moderate price.

VMPET has good barrier properties, light shielding, toughness, and metallic luster; enhanced PET aluminum plating is preferred, with a thick AL layer.

S-PE has good anti-contamination sealing and low-temperature heat sealing.

6. Green tea packaging

Packaging requirements:

Preventing deterioration, discoloration, and changes in flavor, i.e., preventing the oxidation of proteins, chlorophyll, chlorogenic acid, and vitamin C in green tea.

 

 

 

 

Design structure:

BOPP/AL/PE, BOPP/VMPET/PE, KPET/PE

Design rationale:

AL foil, VMPET, and KPET are all materials with excellent barrier properties, providing good barrier properties against oxygen, water vapor, and odors. AK foil and VMPET also have excellent light shielding properties. The product price is moderate.

7. Edible oil

Packaging requirements:

Preventing oxidation and deterioration, good mechanical strength, high burst strength, high tear strength, oil resistance, high gloss, transparency.

 

 

 

 

Design structure:

PET/AD/PA/AD/PE, PET/PE, PE/EVA/PVDC/EVA/PE, PE/PEPE

Design rationale:

PA, PET, and PVDC have good oil resistance and high barrier properties. PA, PET, and PE have high strength. The inner layer PE is a special PE with good anti-sealing contamination and high airtightness.

8. Milk film

Packaging requirements:

Good barrier properties, high burst strength, light shielding, good heat sealing, moderate price.

 

 

 

 

Design structure:

White PE/White PE/Black PE

Design rationale:

The outer PE layer has good gloss and high mechanical strength. The middle PE layer bears the strength, and the inner layer is the heat-sealing layer, with light shielding, barrier, and heat-sealing properties.

9. Ground coffee packaging

Packaging requirements:

Water absorption prevention, oxidation prevention, resistance to hardening of the product after vacuuming, and preservation of the volatile and easily oxidizable aroma of coffee.

 

 

 

 

Design structure:

PET/PE/AL/PE, PA/VMPET/PE

Design rationale:

AL, PA, and VMPET offer good barrier properties, blocking water and gas, while PE has good heat sealing properties.

10. Chocolate

Packaging requirements:

Good barrier properties, light blocking, aesthetically pleasing printing, and low-temperature heat sealing.

 

 

 

 

Design structure:

Pure chocolate varnish/ink/white BOPP/PVDC/cold seal adhesive

Nut chocolate varnish/ink/VMPET/AD/BOPP/PVDC/cold seal adhesive

Design rationale:

PVDC and VMPET are both high-barrier materials. The cold seal adhesive can be sealed at very low temperatures, and the heat will not affect the chocolate. Because nuts contain more oil, they are prone to oxidation and deterioration, so an oxygen barrier layer is added to the structure.

11. Beverage packaging bags

Packaging requirements:

Acidic beverages have a PH value <4.5, undergo pasteurization, and generally require moderate barrier properties.

Neutral beverages have a PH value >4.5, undergo sterilization, and require high barrier properties.

 

 

 

 

Design structure:

Acidic beverages:

PET/PE (CPP), BOPA/PE (CPP), PET/VMPET/PE

Neutral beverages:

PET/AL/CPP, PET/AL/PA/CPP, PET/AL/PET/CPP, PA/AL/CPP

Design rationale:

For acidic beverages, PET and PA provide good barrier properties and withstand pasteurization, as acidity extends shelf life.

For neutral beverages, AL provides the best barrier properties, while PET and PA offer high strength and withstand high-temperature sterilization.

12. Liquid detergent stand-up pouches

Packaging requirements:

High strength, impact resistance, burst resistance, good barrier properties, good rigidity for stand-up, stress crack resistance, and good sealing.

 

 

 

 

Design structure:

① Stand-up: BOPA/LLDPE; Bottom: BOPA/LLDPE.

② Stand-up: BOPA/reinforced BOPP/LLDPE; Bottom: BOPA/LLDPE.

③ Stand-up: PET/BOPA/reinforced BOPP/LLDPE; Bottom: BOPA/LLDPE.

Design rationale:

The above structures have good barrier properties and high material rigidity, suitable for stand-up pouches. The bottom is flexible and suitable for processing. The inner layer is modified PE, with good resistance to seal contamination. Reinforced BOPP increases the mechanical strength of the material and enhances its barrier properties. PET improves the material's water resistance and mechanical strength.

13. Aseptic packaging materials

Packaging requirements:

Both packaging and use are in a sterile state.

 

 

 

 

Design structure:

Coating/AL/Peel layer/MDPE/LDPE/EVA/Peel layer/PET.

Design rationale:

PET is a sterile protective film that can be peeled off. When entering the aseptic packaging area, the PET is peeled off to reveal the sterile surface. The AL foil peel layer is peeled off by the customer when drinking. A drinking hole is pre-punched on the PE layer, and the drinking hole is revealed when the AL foil is peeled off. AL foil is used for high barrier properties, MDPE has good rigidity and good heat adhesion to AL foil, LDPE is inexpensive, and the inner layer EVA has a VA content of 7%. VA > 14% is not allowed to directly contact food. EVA has good low-temperature heat sealing and resistance to seal contamination.

14. Pesticide packaging

Packaging requirements:

Because pesticides are highly toxic and seriously endanger human health and environmental safety, the packaging requires high strength, good toughness, impact resistance, drop resistance, and good sealing.

 

 

 

 

Design structure:

BOPA/VMPET/S-CPP

Design rationale:

BOPA has excellent flexibility, puncture resistance, high strength, and good printability. VMPET has high strength and good barrier properties, and thicker plated materials can be used. S-CPP provides heat sealability, barrier properties, and corrosion resistance, using ternary copolymer PP. Alternatively, multi-layer co-extruded CPP containing high-barrier EVOH and PA layers can be used.

15. Heavy-duty packaging bags

Packaging requirements:

Heavy-duty packaging is used for agricultural products such as rice, beans, and chemical products (such as fertilizers). The main requirements are good toughness and necessary barrier properties.

 

 

 

 

Design structure:

PE/plastic fabric/PP, PE/paper/PE/plastic fabric/PE, PE/PE

Design rationale:

PE provides sealability, good flexibility, drop resistance, and high strength of plastic fabric.

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