The tendency of resin films to sag becomes a significant issue, particularly when they are used as components in large-scale displays or precision devices. In addition, surface reinforcement to protect against scratches and wear during everyday use is also essential.
To meet these requirements, various approaches have been developed, ranging from material selection to processing technologies. In particular, combining materials with high heat resistance and rigidity, as well as applying specialized surface coatings, has proven highly effective in significantly enhancing the performance of resin films.
Sagging Prevention in Resin Films
Deformation Suppression Through Polycarbonate Substrates
The prevention of sagging in resin films is strongly influenced by the properties of the base material. For example, polycarbonate resin has a high heat deflection temperature of approximately 130 °C, which is significantly higher than that of acrylic resin. This makes it resistant to deformation even under elevated temperatures.
Thanks to this excellent resistance to thermal deformation, components such as display panels are less likely to warp or lose their shape due to temperature changes in the operating environment. As a result, long-term stability and reliability of the product can be ensured.
Increasing Rigidity Through a Substrate and Resin Layer Structure
To further enhance sagging resistance, it is effective to laminate an additional resin layer onto the polycarbonate substrate sheet. In particular, laminating an acrylic-based resin layer increases the overall flexural modulus of the sheet.
This improves resistance to bending and results in a more rigid structure. When acrylic-based resin layers are laminated on both sides of the substrate sheet, higher rigidity can be achieved. This also reduces the risk of warpage caused by changes in temperature or humidity.
Strengthening Resin Film Surfaces through Dip Coating
Using Dip Coating to Form a Hard Coat Layer
To protect resin film surfaces from scratches and wear and to improve durability, the formation of a hard coat layer is essential. One effective method for forming this hard coat layer is dip coating. Dip coating is a process in which the target object is immersed in a coating solution and then slowly withdrawn to apply a coating with a uniform film thickness.
This method is applicable not only to flat substrates but also to surfaces with curves or three-dimensional shapes, making it suitable for efficient surface strengthening of complex geometries.
Improving Surface Hardness and Scratch Resistance
Forming a hard coat layer significantly improves the surface hardness and scratch resistance of resin films. This helps suppress the formation of fine scratches during daily handling and use, allowing the surface condition of the film to be maintained over time.
In addition, the refractive index of the hard coat layer is closely matched to that of the underlying acrylic-based resin layer. This suppresses the formation of rainbow-like interference fringes caused by light interference. As a result, high transparency and excellent visibility can be achieved without compromising optical clarity.
Summary
Sagging prevention and surface strengthening of resin films are achieved through a combination of substrate selection, multilayer structure design, and surface treatment technologies.
For sagging prevention, a polycarbonate resin substrate with excellent heat resistance is used, and rigidity is increased through lamination with acrylic-based resin layers. For surface strengthening, forming a hard coat layer by methods such as dip coating improves surface hardness and scratch resistance.
Furthermore, adjusting the refractive indices of the hard coat layer and the underlying resin layer helps suppress interference fringes that would otherwise impair visibility. Through these technologies, resin films can be applied as high-performance materials across a wide range of applications.
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