TPU (thermoplastic polyurethane) hot melt adhesive film is an environmentally friendly, elastic and wear-resistant adhesive film material, which is widely used in automobiles, electronics, medical treatment, sports shoes and other fields. Its unique properties make TPU hot melt adhesive film the preferred material in many high-demand applications. The TPU hot melt adhesive film production method determines its quality, cost and applicability. At present, there are two main methods for the production of common TPU hot melt adhesive film, each method has its advantages and disadvantages. This article will introduce these two commonly used production methods in detail.
The first method: double-layer release paper sandwich method
When producing TPU hot melt adhesive film, the first commonly used method is to extrude the TPU melt through the extrusion die, use two layers of release paper to sandwich the molten TPU material in the middle, and extrude it into a film through a forming roller. The operating steps of this method are relatively simple, mainly including the following key links:
- TPU melt extrusion: TPU particles are first heated to their molten state and extruded through an extruder. At this time, the TPU material is in a flowing state, which is convenient for molding.
- Release paper sandwich: After the TPU melt is extruded, the operator sandwiches it between two layers of release paper. The main function of the release paper is to prevent the TPU melt from direct contact with the molding equipment, ensuring that the melt can pass through the molding roller smoothly without adhering to the molding equipment.
- Molding roller extrusion: The TPU melt sandwiched with release paper is fed between a set of high-temperature heated molding rollers. Through the extrusion of the molding rollers, the TPU melt is compressed and stretched into a film of the required thickness.
- Cooling and cutting: The molded TPU hot melt adhesive film will be cooled and cut into specified sizes. At this time, the film material has the required properties and morphology, ready to enter the subsequent packaging and transportation links.
The advantage of this production method is that the release paper effectively protects the TPU melt during the entire molding process and avoids the problem of film adhesion. Therefore, the produced TPU hot melt adhesive film has higher quality and lower defect rate. Although this method uses two layers of release paper, it may cause a certain amount of material waste, but its high efficiency and stability make this method widely used in industrial production.
Second method: Single-layer release paper and Teflon forming roller method
The second production method is to use only one layer of release paper during the production process and coat the surface of the forming roller with Teflon. As a material with an extremely low friction coefficient, Teflon can effectively reduce the adhesion between the TPU melt and the forming roller and prevent the film from adhering to the surface of the equipment during the production process.
The production steps of this method are similar to the first method, but there are some differences:
- TPU melt extrusion: As in the first method, the TPU particles are first heated, melted and extruded.
- Teflon-coated forming roller: A layer of Teflon coating is applied to the surface of the forming roller. This layer of coating can greatly reduce friction and prevent the TPU melt from adhering to the forming roller.
- Single-layer release paper sandwich: Unlike the first method, the second method uses a single layer of release paper. The molten TPU is sandwiched by a layer of release paper and formed by the forming roller.
- Cooling and cutting: After the TPU hot melt adhesive film is formed, it will be cooled and cut into the required size.
Although this second method has the advantage of lower cost (because only one layer of release paper is used), it also has some disadvantages. First, although the friction coefficient of Teflon coating is low, in actual production, Teflon coating and TPU melt occasionally stick together, resulting in defects such as bubbles and wrinkles on the surface of the film. This will directly affect the quality of the final product and increase the defect rate. Secondly, Teflon coating will gradually fail due to wear and tear during long-term use, so it needs to be re-plated with Teflon regularly, which invisibly increases maintenance costs.
Choose the right production method
Although the second method can reduce the use of one layer of release paper, thereby reducing production costs, many manufacturers prefer the first method considering its higher defect rate and maintenance cost of Teflon coating. The double-layer release paper sandwich method can ensure higher product quality and reduce defects in the production process. Therefore, the first method is often the preferred way to produce TPU hot melt adhesive film.
In summary, although the production methods of TPU hot melt adhesive film have their own advantages and disadvantages, with the continuous development of technology and the improvement of production requirements, manufacturers usually choose the most appropriate production method based on specific production needs and cost control. In actual production, minimizing the defective rate of products, improving production efficiency and reducing maintenance costs are always key goals.
