Reliable Flexible Packaging Solutions for Global Brands

The core raw materials for producing flexible packaging are mainly divided into three categories: substrate film, composite adhesive, and printing ink.

Substrate Film (Classified by Function):

• Printing Layer Substrate (Outer Layer):
  BOPP (Biaxially Oriented Polypropylene): High transparency, good printability, commonly used for the outer layer of packaging for ordinary food and daily necessities.
  

  PET (Polyester Film): High mechanical strength, high temperature resistance, good barrier properties, commonly used for retort pouches and high-end packaging.

  BOPA/NY (Nylon Film): Excellent puncture resistance, abrasion resistance, and toughness, commonly used for frozen foods and vacuum bags.

• Barrier Layer Substrate (Middle Layer, Added as needed):
  AL (Aluminum Foil): High barrier properties, light-blocking, aroma retention, and excellent oxygen and moisture barrier performance.VMPET/VMCPP (Metallized Film): Good metallic luster, lower cost than pure aluminum foil, with good light-blocking and barrier properties.EVOH (Ethylene-Vinyl Alcohol Copolymer): High-barrier transparent film, commonly used in food preservation packaging where visible contents are required.
• Heat-sealable Layer Substrate (Inner Layer):
  PE (Polyethylene): Non-toxic and odorless, with good low-temperature heat-sealing properties. Divided into LDPE (Low Density Polyethylene) and LLDPE (Linear Low Density Polyethylene), it is the most widely used.CPP (Unstretched Polypropylene): High transparency and high-temperature resistance, commonly used for the inner layer of retort pouches or high-transparency flat bags.
• Composite Adhesives:
  Solvent-free adhesives: Environmentally friendly, with no solvent residue, they are currently the mainstream green composite material.Solvent-based two-component polyurethane adhesives: Extremely high bonding strength, commonly used in high-strength retort pouches and corrosion-resistant packaging.
• Printing Inks:
  Using gravure solvent-based inks or environmentally friendly water-based inks / benzene-free and ketone-free inks.

1. Gravure Printing
Principle: The pattern is engraved on an electro-engraved copper plate roller. Ink enters the cells of the roller and is transferred to the surface of the printing layer film (BOPP/PET, etc.).

Process Characteristics: Typically uses reverse printing technology, meaning the pattern is printed on the inside of the film. This way, the printed text and pattern are sandwiched between the film layers, preventing scratches and direct contact with the packaging contents.

2. Lamination
The printed outer film is bonded together with the middle layer (e.g., aluminum foil) and inner layer (e.g., PE/CPP) using adhesive to form a multi-layered composite structure.

Solvent-free Lamination: No heating is required to evaporate the solvent during adhesive application; direct heating and pressing are used, resulting in high speed and no VOC emissions.

Dry Lamination: Adhesive is applied to the substrate, and after the solvent evaporates in an oven, it is hot-pressed onto another substrate layer.

3. Curing/Curing
The laminated roll material is placed in a specialized curing chamber (50℃–60℃ constant temperature) and stored for 24 to 72 hours.

Purpose: To promote complete cross-linking reaction between the main agent and the curing agent, improve peel strength, and completely evaporate any residual solvent odor.

4. Slitting

The cured large roll of film is loaded onto a slitting machine and precisely cut into smaller rolls according to the customer’s specified width using a high-speed circular blade.

Results: If the customer requires automatic packaging (e.g., an automated packaging line) for filling, the slitting finished rolls are the final delivered “roll film” product.

5. Bag Making (For Packaging Bags Only)
If the customer orders individual packaging bags, the slit film rolls will enter the bag making machine, where they will be heated and pressed together by a heat-sealing knife to form the bag shape and then cut.

Common bag types: Three-side seal bags, back seal bags (center seal bags), stand-up pouches, eight-side seal flat bottom bags, zipper bags, etc.

Needle Detection and Quality Inspection: During the bag cutting process, heat seal strength testing, appearance defect detection, and rejection are performed simultaneously.

Quality Inspection: Solvent residue testing (gas chromatograph analysis), heat seal strength, tensile peel strength, and airtightness (differential pressure method for leak testing).

Packaging: Sealed in dustproof inner bags, then palletized and shipped after boxing.