Coating performance is the key to protective film production
Aug 24, 2021
In the packaging industry, there is a special protective material called surface protective film. It is pasted on various metal plates, plastic plates, glass and other surfaces. During transportation, processing, storage and use, the fine surface of the article is protected , Sunsea protective film, which requires excellent pressure-sensitive protective adhesive acrylic adhesive/PU adhesive.
The viscosity and other rheological properties of the adhesive are important properties that affect the coating behavior of the surface protective film. According to the dependence of the viscosity on the shear rate, the fluid can be divided into three types: Newtonian fluid, swelling body and pseudoplastic body, and according to the viscosity cutting Depending on the change of time, the fluid is divided into Newtonian fluid, thixotrope and rheological body. The greater the deviation of the rheological properties of the adhesive from the Newtonian fluid, the more likely to have various quality problems in the coating operation, especially when the adhesive When presenting the properties of an expanded body, its viscosity will increase rapidly with the increase of the coating speed during the coating process,
The key to the production of surface protective film is to select the appropriate coating method and coating machine according to the coating performance of the protective film and the specific requirements of the protective film, and to determine the various process parameters of the coating machine operation. It is necessary to use greater mechanical force to spread the adhesive, so the faster the coating speed, the more difficult it is to obtain a uniform coating, and the substrate is often broken due to excessive force. Even the squeegee is damaged. When the adhesive exhibits thixotropic properties , The leveling of the adhesive layer during coating is very poor, so it is difficult to get a smooth adhesive layer.
