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Leading Manufacturer of Portable Outdoor and Travel Gear, Waterproof Bag
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Leading Manufacturer of Portable Outdoor and Travel Gear, Waterproof Bag
1.The Waterproof LImitations of Traditional Backpacks
In the early days, most outdoor backpacks relied on sewing and external waterproof coatings. However, the needle holes in the seams were prone to water seepage, and their waterproof performance was insufficient in heavy rain. To improve the waterproof performance, plastic heat fusion technology (such as high-frequency welding) was introduced into the industrial field in the 1990s, initially used in products like PVC tents and raincoats. After 2010, with the increasing demand for lightweight outdoor equipment, high-molecular materials such as TPU (thermoplastic polyurethane), which combine flexibility and waterproofing, became the core materials for high-end waterproof backpacks, promoting the large-scale application of high-frequency heat pressing technology.
2.Core Advantages of High Frequency Welding Technology
①Seamless welding, completely waterproof
﹡By applying a high-frequency welding field to excite the frictional heat generation of material molecules, the TPU/PVC coating melts at temperatures ranging from 150 to 450°C. After pressing, a molecular-level fusion interface is formed, completely eliminating the stitch pores.
﹡For example, after the seams of the hiking backpack are fused, it can withstand long-term heavy rain erosion without any leakage.
②Lightweighting and structural flexibility
﹡Removing redundant components such as stitches and waterproof sealing strips, the weight of the waterproof travel backpack is reduced.
﹡Supports one-time molding of complex 3D cutouts (such as curved back panels, irregular pockets), enhancing design flexibility.
③Aesthetics
﹡The surface has no pinholes or indentations. It can simultaneously complete processes such as logo embossing and decorative textures.
3. Detailed Explanation of Production Process
Stage 1: Material pre-preparation
﹡Film Lamination Reinforcement: Place the TPU/PVC film on the oxford cloth or nylon base fabric, and use a hot-press laminating machine to adhere it, forming a waterproof composite material. The laminating machine is equipped with hydraulic adjustment and travel switches, suitable for different thickness materials .
﹡Cutting design: The laminated material is laser-cut according to the mold, and then divided into components such as the back panel, side wings, and bag cover, with a 0.5 - 1 cm welding allowance reserved at the edges.
Stage 2: High-frequency welding forming
Equipment configuration:
﹡Core parameters: Power range 5 - 15KW (for large backpacks, use 8 - 15KW models), air pressure boosting (0.5 - 0.8MPa), welding temperature typically set at 400℃ (the optimal melting point of TPU);
﹡Safety system: The spark protector continuously monitors the current. In case of abnormal discharge, it cuts off the power supply within 0.03 seconds to prevent damage to the mold .
Layered fusion welding sequence:
﹡Main body formation: Align the side and bottom fabric pieces with the mold, and use high-frequency welding to form a U-shaped barrel-like structure;
﹡Sealing end face: The front/back pieces are fused with the main body, and rounded corners are used at the corners to prevent stress cracking;
﹡Attachment integration: Shoulder strap buckles, waterproof zipper bases, etc. are embedded through local hot pressing (custom molds are required).
Stage 3: Post-processing and Quality Inspection
﹡Sealing Enhancement: The sewing area (such as the seam of the shoulder strap) is covered with a TPU sealing strip and undergoes secondary heat pressing to eliminate water leakage channels ;
﹡Foldable packaging: After being folded three times, the foldable backpack can be stored in the front storage bag, reducing its volume.
4.Summary
The high-frequency hot pressing process replaces chemical bonding and mechanical sewing with physical welding, reshaping the manufacturing paradigm of outdoor waterproof backpacks. Its core technology - the RF welding field molecular excitation and precise temperature control system - not only achieves "impermeable" protective performance, but also drives outdoor equipment to evolve towards "minimalist design and extreme lightness". In the future, with the adaptation of eco-friendly materials such as biobased TPU and degradable EVA, this process will further lead the innovation wave of sustainable outdoor equipment 🌊.
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