The weather changes quickly in Summer. When walking outside, the most afraid is that the coming storm, and it doesn’t matter that people get wet, what’s more, worrying is that the important documents, money, electronic equipment and clothes in the backpack are wet, and the loss is not a little bit. Therefore, it is more important to have a waterproof backpack. So, how does the backpack prevent the water from entering the bag? What is the difference between waterproof backpacks and ordinary backpacks?
The biggest difference between waterproof backpacks and ordinary backpacks is the fabric.
The fabric used in ordinary backpacks is easy to get wet when exposed to water. Some fabrics are water-repellent, which is a coating that plate to the surface to prevent part of the water from entering the backpack. However, it is useless in heavy rain, besides, the coating has a certain service life, thus the water-repellent function will gradually fade over time.
Most of the fabrics used in waterproof backpacks are air-tight or air-impermeable, with a thicker coating, and even a film on the other side for better waterproof performance.
Nowadays, waterproof backpacks in the market are basically made of TPU fabrics. TPU is the abbreviation of thermoplastics urethane, which is a polymer material made by the reaction of diphenylmethane diisocyanate or toluene diisocyanate, diisocyanate molecules and macromolecular polyols and low molecular polyols. TPU fabric has many excellent properties such as super waterproof, antibacterial, mildew resistance, wear resistance, cold resistance, oil resistance, water-resistance and aging resistance.
Sewing VS High-frequency Welding
The ordinary backpacks generally use sewing technology, you can see the stitching holes and threads on the surface of the backpack, and the external air or water can enter the backpack through these ways.
However, high-frequency welding technology applies thermal melting to integrate the backpack into a whole. There are no gaps on the surface of the backpack to ensure that water or even air can not enter the backpack, thus it is completely waterproof.
Whether waterproof backpacks or ordinary backpacks, if the bag mouth is zip opening, which involves the choice of zipper accessories. Ordinary backpacks choose the general zipper, which the water will leak in. While waterproof backpacks use high-quality airtight zippers, which is waterproof and anti-penetrate, can effectively keep the items in the bag dry all time.
Generally, there are two closed methods of waterproof backpacks: The first kind of bag mouth is roll-top, that is, folding the mouth three times at least and use buckles or other fasteners to close it, that can form a sealed room in the main compartment. The other one is airtight zipper opening. The airtight zipper is a high-level waterproof zipper. This kind of zipper has a high cost and is generally used for outdoor backpacks, cycling bags, waist bags, etc.
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