The thickness of a Zipper briefcase's waterproof coating is a key parameter influencing its protective effectiveness. Its design must balance waterproof performance, durability, and user comfort. The waterproof coating creates a continuous protective layer on the briefcase's surface through a physical barrier, preventing moisture from penetrating to the documents within. The thickness of this layer directly determines the material's ability to withstand water pressure and its stability during long-term use. Too thin or too thick a layer can lead to performance defects.
If the Zipper briefcase's waterproof coating is too thin, its protective effectiveness will be significantly weakened. A thin coating is unable to withstand sustained water pressure shock, especially in humid or rainy environments. Water can easily penetrate through the coating's micropores or worn areas, causing moisture to enter the documents within. Furthermore, a thin coating is less resistant to mechanical friction, and scratches and impacts from daily use can easily cause the coating to break, further reducing its waterproof performance. Prolonged exposure to UV rays or temperature fluctuations can also accelerate aging and cracking, shortening the briefcase's lifespan.
Conversely, if the Zipper briefcase's waterproof coating is too thick, while improving short-term water resistance, it can also cause structural problems. An excessively thick coating increases the material's rigidity and reduces the briefcase's flexibility, causing excessive stress on the zipper during opening and closing, leading to coating peeling or zipper jamming. Furthermore, thick coatings can become brittle and crack in low temperatures, weakening the waterproofing effect. Furthermore, excessively thick coatings significantly increase the briefcase's weight, compromising portability and defeating the purpose of its lightweight design.
The thickness of a zipper briefcase's waterproof coating must be precisely tailored to the specific application scenario. For example, for business use involving frequent rainy weather, a medium coating thickness is required to provide both rain resistance and flexibility. For briefcases used indoors for document storage, a thinner coating can be used to balance cost and basic protection needs. Some high-end products utilize a layered coating technique, increasing the coating thickness in key areas (such as around the zipper and at the corners) to provide localized enhanced protection while maintaining overall lightweight performance.
Coating thickness is also closely related to the material properties of the zipper briefcase. If the bag's body is made of high-density nylon or polyester, the fiber structure inherently provides some water resistance, allowing the coating to be appropriately thinned. However, if the material is natural fiber or open-pore fabric, a thicker coating is required to compensate for the water resistance shortcoming. Furthermore, the adhesion between the coating and the substrate is affected by thickness. Excessively thick coatings can cause separation from the substrate due to internal stress, requiring enhanced bonding through formulation optimization or surface treatment.
In the production of zipper briefcases, controlling the thickness of the waterproof coating requires precise craftsmanship. Spraying achieves uniform coverage by adjusting the spray gun pressure and coating viscosity, but requires strict control of ambient humidity to prevent dripping. Dip coating is suitable for simple briefcases, but can lead to excessive buildup of coating at the edges. Some brands use laser engraving technology to create micro-nanostructures on the coating surface, reducing contact area and minimizing water penetration without excessively increasing the coating thickness. When purchasing a zipper briefcase, consumers can initially assess coating thickness by touch and visual inspection. A high-quality coating should feel even, be free of graininess, and exhibit no cracks at the bends. Avoid contact with sharp objects during use and clean regularly to prevent stains from eroding the coating. If you find that the coating is whitening, peeling, or its waterproof performance is reduced, you should contact after-sales service in time to avoid damage to the documents due to coating failure.
