The Characteristics Of 11 Kinds Of Plastic Films In Packaging Bags

Author : Guangzhou Lefeng Plastic Bags Co.,Ltd

Update time : 2022-05-14 10:08:20

As a printing material, plastic film is used as a packaging bag after printing. It has the characteristics of lightness and transparency, moisture resistance and oxygen resistance, good air tightness, toughness and folding resistance, smooth surface, can protect the product, and can reproduce the shape and color of the product advantage.

With the development of the petrochemical industry, there are more and more varieties of plastic films. Commonly used plastic films include polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polyester film (PET), polypropylene (PP), nylon (PA), etc. In addition, there are many other types of plastic films. Guangzhou Lefeng, a professional flexible packaging manufacturer, believes that it is necessary to understand the characteristics of plastic films before customizing packaging bags.

1. Polyvinyl Chloride (PVC)

The advantages of PVC film and PET are similar. They are both transparent, airtight, and acid and alkali resistant. In the early days, many food packaging bags were made of PVC packaging bags. However, PVC may release carcinogens due to incomplete polymerization of some monomers in the manufacturing process, so it is not suitable for filling food-grade substances. Now most of them have been switched to PET packaging bags, and the material symbol is No. 3.

2. Polystyrene (PS)

The water absorption of PS film is low, but its dimensional stability is good, and it can be processed by injection molding, compression molding, extrusion and thermoforming. Generally, it is divided into two categories: foamed and unfoamed according to whether it has undergone the foaming process. Unfoamed PS is mainly used in building materials, toys, stationery, etc. It can also be commonly made into containers filled with fermented milk products (such as Yakult, Jianmei, Duoduo and other dairy products or lactic acid products), etc. In recent years, it has also been widely used to make disposable Cutlery, marked with material symbol No. 6.

3. Polypropylene (PP)

Ordinary PP film is formed by blow molding, which has a simple process and low cost, but its optical performance is slightly lower than that of CPP and BOPP. The biggest feature of PP is high temperature resistance (about -20℃~120℃), and the melting point is as high as 167℃. It is suitable for filling soy milk, rice milk and other products that need steam sterilization. Its hardness is higher than PE, and it is mostly used to make container caps, and the material symbol is No. 5. Identification method: Generally speaking, PP has higher hardness and glossier surface, and does not produce irritating odor when burning, while PE has a heavier candle odor.

4. Polyester film (PET)

Polyester film (PET) is a thermoplastic engineering plastic. The thick sheet is made by extrusion method, and then the film material is made by biaxial stretching. Polyester film is characterized by excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high and low temperature resistance, chemical resistance, oil resistance, air tightness and fragrance retention. One of the composite film substrates, but with poor corona resistance and high price. The thickness of the film is generally 0.12mm, which is often used as the outer layer material of the food packaging bag, and has good printability. The material symbol marked in plastic products is No. 1.

5. Nylon (PA)

There are many varieties of nylon plastic films (polyamide PA) currently industrially produced, among which the main varieties used to produce films are nylon 6, nylon 12, nylon 66 and so on. Nylon film is a very tough film with good transparency and good gloss. Tensile strength, tensile strength, high and low temperature resistance, oil resistance, organic solvent resistance, abrasion resistance and puncture resistance are all good, and the film is relatively soft and has excellent oxygen barrier properties, but the barrier property to water vapor is relatively low. Poor, moisture absorption and moisture permeability are large, and heat sealing performance is poor. It is suitable for packaging hard items, such as greasy food, fried food, vacuum-packed food, retort food, etc.

6. High Density Polyethylene (HDPE)

HDPE membrane is known as geomembrane or impermeable membrane. Its melting point is about 110℃-130℃, and its relative density is 0.918-0.965kg/cm3. It is a kind of thermoplastic resin with high crystallinity and non-polarity. The appearance of the original HDPE is milky white, and it is translucent to a certain extent in the thin section. Has good high and low temperature resistance and impact resistance, even at temperatures as low as -40F. Its chemical stability, rigidity, toughness, mechanical strength, and tear resistance are all excellent, and with the increase in density, mechanical properties, barrier properties, tensile strength and heat resistance will increase accordingly. Corrosion by organic solvents, etc. Identification method: Most of them are opaque, feel like wax, and there is a rustling sound when the plastic bag is rubbed or rubbed.

7. Low Density Polyethylene (LDPE)

LDPE film has low density, softness, low temperature resistance, and good impact resistance. LDPE is mostly used in plastic packaging bags, marked with a material symbol of No. 4, and its products are mostly used in civil engineering and agricultural fields, such as geomembrane, agricultural film (shed film, mulch film, green storage film, etc.). Identification method: The plastic bag made of LDPE is softer and less rustling when rubbed. The outer packaging plastic film is soft and easy to tear is LDPE, and the more brittle and hard is PVC or PP film.

8. Polyvinyl Alcohol (PVA)

Polyvinyl alcohol (PVA) high-barrier composite film is a film with extremely high barrier properties formed by coating the modified polyvinyl alcohol water-soluble liquid on the substrate with polyethylene plastic as the base material. Since the polyvinyl alcohol high-barrier composite film has good barrier properties and meets the requirements of environmental protection, the market prospect of this kind of packaging material is very bright, and there is a broad market space in the food industry.

9. Cast polypropylene film (CPP)

Cast polypropylene film (CPP) is a non-stretched, unoriented cast film produced by melt casting quenching. It is characterized by fast production speed, high output, good film transparency, gloss, barrier property, softness, and thickness uniformity, and can be resistant to high temperature cooking (cooking temperature above 120 ℃) and low temperature heat sealing (heat sealing temperature less than 125°C), the performance balance is excellent. Follow-up work such as printing and compounding is convenient, and it is widely used in the packaging of textiles, food, and daily necessities. It is used as the inner substrate of compound packaging, which can extend the shelf life of food and increase its aesthetics.

10. Biaxially polypropylene film (BOPP)

Biaxially polypropylene film (BOPP) is a kind of transparent flexible packaging bag material developed in the 1960s. It is a special production line that mixes polypropylene raw materials and functional additives, melts and kneads them, and makes them into sheets. Stretch into film. This film not only has the original advantages of low density, corrosion resistance and heat resistance of PP resin, but also has good optical properties, high mechanical strength, rich source of raw materials, and excellent printing performance. Laminates to other substrates with high clarity and gloss, excellent ink absorption and coating adhesion, high tensile strength, excellent grease barrier properties, low static properties, and more.

11. Aluminized

Aluminized film combines the properties of plastic film and metal. The function of aluminum plating on the surface of the film is to block light and prevent ultraviolet radiation, which not only prolongs the shelf life of the contents, but also improves the brightness of the film. Therefore, aluminized film is widely used in composite packaging, mainly used in the packaging of dry and puffed food such as biscuits, and the outer packaging of medicine and cosmetics.

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