On cold winter days, a small, transparent hot water bag often brings the most immediate warmth and comfort. The source of this transparent hot water bag's warmth comes from humble PVC granules.
1. Starting Material: PVC Granules
PVC (polyvinyl chloride) is one of the most widely used plastics in the world. Through formulation, PVC granules can be made hard or soft, transparent, or colored. In the production of transparent hot water bags, soft, transparent PVC granules are used. Environmentally friendly plasticizers, stabilizers, and colorants are added to ensure crystal clearness, flexibility, and high-temperature resistance.
2. Film Forming: From Granules to Film
These PVC granules first enter an extruder, where they are melted at high temperatures and then stretched into a uniform film through a calendering process. The film requires not only high transparency but also excellent flexibility and thickness stability, which are key to ensuring the hot water bag's ability to withstand the impact of hot water.
3. Molding Process: High-Frequency Heat Sealing
The transparent hot water bag's main body consists of two sheets of PVC film, one on the front and one on the back. During production, workers align the two sheets and then use high-frequency heat sealing (high-frequency welding) technology to rapidly fuse the films together under a high-frequency electric field, forming a strong bag structure and simultaneously embossing a non-slip texture. The bottle opening is typically injection-molded from rigid PVC or TPR and then welded to the bag.
4. Quality Inspection: A Guarantee of Safety
Every hot water bag undergoes a water-filled pressure test before shipment to verify leaks and poor welds. Only products that pass this rigorous inspection reach consumers, ensuring warmth and safety for daily use.
5. Applications and Extensions: The More Possibilities of PVC
Beyond transparent hot water bags, soft PVC granules are also widely used in transparent, flexible products such as ice packs, inflatable pillows, storage bags, and medical supplies. Different modified formulations allow PVC to be used in a wider range of everyday applications.
Behind this small, transparent hot water bottle lies the culmination of a scientific formula of PVC particles combined with modern craftsmanship. From particles to film, then to welding and molding, it undergoes a series of steps, ultimately delivering warmth to everyone. These invisible materials and technologies make the "little happiness of warmth" of winter within reach.
Post time: Sep-16-2025
