# Three-side Sealed Flat Bags: Flat small pouches for seasonings, medicinal powder samples and vacuum-cooked food Stand-up Zipper Bags: With gusseted bottom for self-standing and reclosable zippers, for tea, meal replacement powder and traditional Chinese medicine granules Back-sealed Gusseted Large Bags: Large-capacity sacks of 20–50kg for food additives and pharmaceutical powders Vacuum Bags: Zipper-free vacuum-sealed pouches for braised food and frozen dry goods Large-size Aluminum Foil Liner Bags: Matched with bulk bags, flat mouth or with discharge valve ## II. Three-layer Structure (Outside to Inside) Standard thickness configuration: 12μm PET outer layer + 7–9μm solid aluminum foil middle layer + 50–80μm PE inner layer, laminated integrally with adhesive and resistant to manual peeling. 1. Layer 1: PET Polyester (Outermost Layer) Functions: Wear-resistant, scratch-proof, dimensionally stable, supports high-definition color printing; blocks minor oil stains and external dust; short-term temperature resistance ranging from -40℃ to 110℃. Appearance: Smooth flat surface for color graphic printing. 2. Layer 2: AL Solid Aluminum Foil (Core Barrier Layer, different from aluminized film bags) Adopts continuous solid aluminum foil rather than aluminum-coated film with zero pinholes. Functions: 100% light shielding, complete barrier against oxygen, moisture vapor, ultraviolet rays and odors; prevents oxidation of food and decomposition of light-sensitive pharmaceuticals. Visual feature: A silvery metallic sheet is visible when the laminate is torn open. 3. Layer 3: PE Polyethylene (Innermost Product-contact Layer) Food/medical grade PE with no peculiar odor and chemical inertness. Core function: Heat-sealing layer that fuses and seals the pouch under heating; resistant to oil at ambient temperature and prevents powder leakage. Limitation: Not resistant to high-temperature retort sterilization at 121℃; delamination occurs under prolonged heating above 100℃. ## III. Core Physical Properties Barrier performance: High oxygen and moisture barrier, full light shielding, far superior to aluminized film bags and PE bags. Temperature resistance: Suitable for ambient temperature and freezing (-40℃); not applicable to boiling or high-temperature retort sterilization. Puncture resistance: Standard version without nylon layer, easily pierced by sharp bones or hard particles. Sealing performance: Firm heat seal, ideal for vacuum packaging and general separate packaging. Aroma retention: Excellent fragrance locking without odor cross-contamination, restrains rancidity of oils and fats. ## IV. Details of Food-grade 3-layer PET/AL/PE Aluminum Bags 1. Production Standards Comply with national standards GB 4806.7 and GB 4806.9 for food-contact materials; all raw materials, inks and adhesives are food-grade; produced in ordinary printing workshops without mandatory Class 10,000 cleanrooms. 2. Applicable Products Long-term storage of tea, nuts, wolfberries, dry goods, vacuum braised food, frozen grains, protein powder, food additives and general snacks. 3. Advantages & Disadvantages Advantages: Cost-effective, full light shielding for freshness retention, vacuum-compatible and printable in full color. Disadvantages: Not resistant to high-temperature retort; vulnerable to piercing by hard objects; incompatible with EO ethylene oxide sterilization. ## V. Details of Medical-grade 3-layer PET/AL/PE Aluminum Bags 1. Mandatory Production Requirements Comply with YBB pharmaceutical packaging material standards; manufactured in Class 10,000 / Class 100,000 dust-free cleanrooms; adopt low-precipitation pharmaceutical adhesives and non-migratory pharmaceutical inks; finished products undergo heavy metal and extractable substance testing. 2. Applicable Products Subpackaging of traditional Chinese medicine granules, external plasters, disinfection powder, common non-sterile bulk drugs and Chinese herbal slices; not for surgical instruments requiring high-temperature or EO sterilization (sterilization causes delamination). 3. Exclusive Medical Restrictions For ambient-temperature sealed storage only, cannot serve as sterilization pouches. Only for packaging external-use and non-sterile pharmaceuticals. Sterile surgical supplies require PET/AL/PP structure instead. Food-grade 3-layer aluminum bags are strictly prohibited to replace medical-grade ones due to substandard cleanliness and extractable indicators. ## VI. Distinction from Easily Confused Packaging Materials (Quick Identification) vs 4-layer NY/AL/PE: 3-layer version without nylon, lower cost and poor puncture resistance; 4-layer version added with nylon for enhanced puncture resistance at higher price. vs Retort bags PET/AL/RCPP: 3-layer bags have PE inner layer without high-temperature resistance; retort bags with RCPP inner layer withstand 121℃ sterilization. vs Aluminized VMPET/PE bags: 3-layer bags adopt solid aluminum foil with complete barrier; aluminized film only features a thin aluminum coating with weak barrier, light transmittance, unfit for long-term pharmaceutical storage. ## VII. Summary of Application Scenarios Food Industry: Ambient-temperature dry goods, frozen fresh food, vacuum cooked food and powder raw materials (excluding high-temperature retort ready meals). Pharmaceutical Industry: Non-sterile oral granules, external ointment and powder, light-sensitive general pharmaceuticals. Industrial Supporting Uses: Bulk bag inner liners, moisture-proof and light-shielding packaging for electronic components.