Classification of food packaging bag materials
| name | polyethylene | HPLDPE | LPHDPE | Linear Low Density Polyethylene | Polypropylene (BOPP, OPP) | polystyrene |
| abbreviation | PE | LDPE | HDPE | LLDPE | PP | PS |
| feature | Lightest plastic for food packaging | The main disadvantage is brittleness | ||||
| Water resistance | good | higher than LDPE | Water vapor transmission rate similar to HDPE | Poor, lower than PE | ||
| Gas barrier | Difference | Difference | higher than LDPE | Difference | Oxygen transmission rate also similar | Difference |
| Mechanical strength | Low | higher than LDPE | higher than LDPE | Good, above PE | Good rigidity and high brittleness; poor impact resistance | |
| Extensibility | good | good | ||||
| Low temperature resistance | very good | Worse than PE -17℃ becomes brittle | good | |||
| High temperature resistance | Difference | excellent | Poor, for 60℃-80℃ | |||
| transparency | not tall | higher | lower than LDPE | good | good, Gundam 88%-92% | |
| Printing performance | poor, needs to be dealt with | poor, needs to be dealt with | ||||
| heat sealability | very good | good | lower than LDPE | Higher than HDPE | Worse than PE | |
| flexibility | good | lower than LDPE | better | |||
| Processability | good | lower than LDPE | good | |||
| health and safety | good | higher than PE | good, non-toxic, odorless | |||
| scope of application | Adapt to the freezing treatment of food | It is mainly made into film, which is used for food with lower packaging requirements, dry food with moisture-proof requirements, fresh-keeping packaging for fresh fruits and vegetables; packaging for frozen foods | Compared with LDPE, under the same strength, raw materials can be saved, and it can be used as a heat-sealing layer of composite film for packaging of high-temperature sterilized food | It is mainly made into film, which is used for packaging meat, frozen food, and dairy products. It has poor gas barrier properties and cannot meet the long-term maintenance requirements. | The film needs to be directional stretched, which is better than CPP. It can pack oily food, can replace cellophane to pack snacks and bread, and can be used as twisted packaging for candies and snacks to make various forms of ropes and belts. | Made into transparent food boxes and fruit bowls, the brightly colored foamed EPS can be used as thermal insulation and cushioning packaging materials, such as: fast food boxes |
The materials used in common food packaging bags are divided into six categories:
1. Material: BOPP/LLDPE two-layer composite
Features: Moisture-proof, cold-resistant, low-temperature heat-sealing and strong tensile force
Uses: instant noodles, snacks, frozen snacks, powder packaging, etc.
2. Material: BOPP/CPP two-layer composite
Features: Moisture-proof, oil-resistant, high transparency, good stiffness
Uses: instant noodles, biscuits, candies, all kinds of light food
3. Material: BOPP/VMCPP composite
Features: Moisture-proof, oil-resistant, oxygen barrier, shading, good stiffness
Composite bag
Uses: All kinds of dry food, fried food, potato chips
4. Material: BOPP/VMPET/LLDPE three-layer composite
Features: moisture-proof, oxygen barrier, shading
Uses: all kinds of food, rice snacks, snacks, tea
5. Material: PET/CPP two-layer composite
Features: moisture-proof, oxygen barrier, fragrance preservation, high temperature resistance
Uses: steaming, alcoholic food, aroma food
6. Material: PET/PET/CPP three-layer composite
Features: Moisture-proof, high temperature resistance, easy to seal
Uses: powder packaging, soy sauce, liquid, shampoo
