How are plastic packaging bags produced?

Many companies upgrading their product packaging want to know if the production processes and materials of plastic packaging bags meet their needs. Today, Shunxingyuan Packaging, a professional flexible packaging manufacturer, will share detailed basic knowledge based on its rich industry experience. Let's see if you've missed anything?

I. Production Process Flow

II. Printing

Rotogravure printing: This refers to the process of making the text and patterns on the original into a printing plate, applying ink to the surface of the printing plate, and transferring the images on the printing plate to the surface of the material being printed through pressure, accurately and massively replicating prints identical to the original.

Surface printing and reverse printing.

III. Lamination

Basic principle of plastic composite flexible packaging: Each material has different advantages and disadvantages. By using a medium (such as glue) to bond two or more layers of materials together, the packaging film and bag achieve better performance. This technology is called "lamination process" in the production process.

IV. Curing

The purpose of curing is to accelerate the curing speed of the adhesive between materials.

V. Slitting

The printed and laminated materials are slit into the specifications required by the customer.

VI. Bag Making

The printed, laminated, and slit materials are made into various bags required by the customer. Various bag types can be produced: center-sealed bags, side-sealed bags, stand-up pouches, K-type bags, R bags, quad-sealed bags, zipper bags.

VII. Quality Control

1. Raw material inspection before warehousing

2. Online product inspection

Print inspection —Residual solvents, registration, etc.

Composite inspection —Lamination strength, bubbles, wrinkles, etc.

Bag making inspection —Seal strength, dimensional deviation, etc.

3. Product inspection before shipment

VIII. Commonly Used Printing Materials

BOPP

Biaxially oriented polypropylene, it is a film formed after biaxial orientation, it does not have heat-sealing properties, and is commonly used as a printing material. Due to its excellent moisture-proof properties, it is suitable for surface printing materials for hygroscopic foods such as biscuits, dried fruits, puffed foods, and melon seeds.

KOP

Coated biaxially oriented polypropylene, is A layer of about 1-2um polyvinylidene chloride (PVDC, also known as K coating) is coated on the surface of OPP, so KOP has both the properties of OPP and the advantages of PVDC. It is often used for mooncakes and other foods that require oxygen and water barriers. KOP has a similar barrier function to aluminum foil, is transparent, and allows the contents of the packaging to be seen.

PCO

Biaxially heat-sealable polypropylene film, it has The properties of OPP and the properties of double-sided heat sealing; often used for packaging of disks and seaweed.

PL

Biaxially oriented polypropylene pearlescent film, it is made from polypropylene resin as the main raw material, with a certain amount of pearlescent powder added, and biaxially oriented. Used for packaging cosmetics, soap, labels, etc.

PET

Polyester film

and Like OPP, it is a secondary biaxially oriented film that is stretched longitudinally and then transversely, or stretched longitudinally and transversely simultaneously, and then heat-set. Commonly used as printing materials for machine packaging rolls, high-temperature cooking bags, zipper bags, etc.

KPET

Chinese name: Coated polyester film, is A layer of about 1-2um polyvinylidene chloride (PVDC, also known as K coating) is coated on the surface of PET.

Therefore, KPET has both the properties of PET and the advantages of PVDC. It is often used for mooncakes and other foods that require oxygen and water barriers. Like KOP, it has a similar barrier function to aluminum foil, is transparent, and allows the contents of the packaging to be seen. Its excellent high-temperature resistance makes it more suitable for machine packaging and other bag types requiring high high-temperature resistance.

NY

Nylon, vacuum packaging, freezing, and high-temperature cooking food packaging; commonly used thickness is 15um, because it is very thin, it makes a rattling sound when moved; density is 1.15g/cm3.

PVC

Polyvinyl chloride, generally used for bottle labels, single-layer material, no lamination is required after printing, and PVC glue (alcohol and cyclohexanone in a 1:1 ratio) is used for bonding; commonly used thickness: 40um.

Mat-opp

Biaxially oriented polypropylene matte film, commonly used for packaging of puffed foods, mooncakes, paper towels, and cosmetics.

IX. Commonly Used Composite Materials

CPP

Unoriented polypropylene, unlike the oriented OPP, CPP is cooled and solidified in its original state after film formation. CPP is the most commonly used heat-sealing material. As a printing material, it is often used for packaging paper towels; as a composite material, it is often used in combination with other materials as a heat-sealing layer.

PET

Unoriented polyethylene, commonly used PE includes IPE, CPE, LLDPE, and ordinary PE. Like CPP, it is the most commonly used heat-sealing material. It is used in packaging for dairy products, shampoos, detergents, and other chemical products. In addition to being commonly used as a surface printing material, it can also be used as a composite material. However, it does not have heat-sealing properties and cannot be placed in the heat-sealing layer. It is generally used as an intermediate composite layer in products, which can increase the stiffness and oxygen barrier properties of the bag.

VMPET

Aluminum-coated polyester film, that is, A layer of aluminum foil is vapor-deposited on the surface of PET, combining the properties of PET and aluminum foil.

VMCPP

Aluminum-coated unoriented polypropylene, that is, A layer of aluminum foil is vapor-deposited on the surface of CPP, combining the properties of CPP and AL.

AL

Aluminum foil has excellent insulation and light-shielding properties. Aluminum foil itself has low strength and no heat-bonding properties, and is prone to breakage at folds, so it is rarely used alone. It is generally used for products that are very sensitive to oxygen and moisture, and in high-end composite flexible packaging, it has very good moisture-proof, oxygen-proof, and UV-proof properties.

NY

Nylon, in addition to being commonly used as a surface printing material, can also be used as a composite material. It does not have heat-sealing properties and cannot be placed in the heat-sealing layer. It is generally used as an intermediate composite layer in products, which can increase the sealing strength and puncture resistance of the bag; it is often used in the intermediate layer of bags that require pressure resistance and high-temperature sterilization. For example, jelly bags, detergent bags, chestnut bags, etc. Its oil resistance makes it suitable for packaging meat and other high-oil products.

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