The Perfect Integration of Innovative Closure Technology and Eco-Friendly Packaging

1. Material Pretreatment

• Film Extrusion:
  Plastic particles such as PE and PP are melted and plasticized by a twin-screw extruder, then extruded into films through a die. The thickness is usually controlled between 0.02-0.20mm, and for special applications (such as cold chain packaging), it can be increased to over 0.3mm.
• Paper Processing:
  White kraft paper needs to undergo oil and moisture resistance coating treatment. The coating amount of water-based adhesive must be precisely controlled at 5-8g/m² to ensure bonding strength and recyclability.

2. Closure System Integration

• High-Frequency Heat Pressing Process:
  Suitable for thermoplastic materials such as PVC and PE. Printed film sheets are placed between copper molds, and high-frequency electric fields polarize material molecules to generate heat. The material is melted and bonded at 120-180℃ under a pressure of 0.5-1.5MPa, forming a self-adhesive zipper structure.
• Adhesive Bonding:
  Paper or composite materials use food-grade water-based adhesives. The zipper strips are bonded to the bag body via roller pressing equipment at 60-80℃, with a peel strength of ≥3N/15mm.
• Ultrasonic Welding:
  For non-woven fabrics or multi-layer composite structures, ultrasonic vibration causes frictional heating of molecules at the material interface, achieving seamless welding with a welding strength of over 50N/15mm.

3. Forming and Post-Processing

• Bag Forming:
  Heat sealing is performed using three-side seal, stand-up pouch, or three-dimensional bag molds. The heat-sealing temperature is adjusted according to the material (e.g., PLA zippers need to be controlled at 130-150℃), with a pressure of 0.3-0.8MPa and a duration of 0.5-1 second.
• Printing and Surface Treatment:
  Eight-color gravure printing or digital printing technology is adopted, and inks must pass FDA food contact certification. Matte, frosted, or anti-static coatings can enhance product functionality.
• Quality Inspection:
  Includes sealability testing (dye penetration method or vacuum negative pressure method), heat-sealing strength (tested by electronic tensile machine ≥35N/15mm), zipper opening-closing lifespan (≥5000 cycles), and compliance review of environmental certifications (such as FSC, BPI).

Application Fields and Market Trends

• Food and Daily Chemical Packaging:
  Transparent stand-up zipper bags are widely used for packaging dried fruits and snacks. Their moisture resistance and reusable sealability extend the product shelf life. FSC-certified paper-based toothless zipper bags have become a new choice for high-end cosmetics and gift packaging, with surfaces that can be printed with exquisite patterns while displaying contents.
• Medical and Industrial Protection:
  Medical-grade toothless zipper bags adopt a multi-layer PP/PE composite structure. After ethylene oxide sterilization, they are used for medical device packaging, with sealing performance resistant to 121℃ high-temperature cooking. In the industrial field, zipper bags made of weather-resistant polyester materials are used for transporting precision parts, capable of withstanding extreme environments from -40℃ to 80℃.