Protective Film with Dual-Layer Base for Heat Bending
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Solution Overview
Problem
The existing protective films for resin substrates do not form a gripping part that allows for easy peeling after heat bending, leading to time-consuming and labor-intensive removal processes, affecting the productivity and quality of lenses and other resin-based products.
Innovation Solution
A protective film with a base material layer and a pressure-sensitive adhesive layer, where the base material layer is a laminate with a thermoplastic resin having a melting point of 150°C or higher and a second layer with a melting point lower than 120°C, allowing a gripping part to form during heat bending, facilitating smooth peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a protective film with a single-layer base material is used, then the structure is simple and easy to manufacture, but the film cannot be easily peeled off after heat bending because no gripping part is formed
Solution Approach 1:
The base material layer is divided into two layers with different melting points: a first layer (melting point ≥150°C) that maintains structural integrity and a second layer (melting point <120°C) that forms a gripping part. This segmentation allows the film to be both easy to manufacture and easy to peel off after heat bending.
Solution Approach 2:
Different parts of the base material layer have different thermal properties. The second layer is specifically designed with a lower melting point to locally form a gripping part that protrudes from the resin substrate, while the first layer maintains higher melting point characteristics for overall structural stability.
2Reliability
If the protective film is made with high adhesion to ensure it stays attached during heat bending, then the film remains firmly attached during processing, but the film becomes difficult to peel off after heat bending
Solution Approach 1:
The adhesion characteristics are changed by utilizing the temperature-dependent melting behavior of the second layer. During heat bending at high temperature, the second layer melts and provides strong adhesion. After cooling, the second layer solidifies with reduced adhesion, enabling easy peeling through the formed gripping part.
Solution Approach 2:
The second layer is pre-designed to melt at a specific temperature range during the heat bending process, creating the gripping part in advance. This preliminary thermal action ensures the film remains attached during processing while automatically preparing the peeling structure for subsequent removal.
3Ease of operation
If a gripping part is formed by making the protective film protrude from the edge, then easy peeling is enabled, but the film may adhere to the mold during heat bending
Solution Approach 1:
The gripping part is formed locally at the edges of the protective film where the second layer protrudes, while the central area maintains strong adhesion through the pressure-sensitive adhesive layer. This local differentiation enables easy peeling at the edges without causing harmful adhesion to the mold during heat bending.
Solution Approach 2:
The protective film is segmented into an adhesion zone (central area with pressure-sensitive adhesive) and a peeling zone (edges with protruding second layer). This segmentation allows the film to simultaneously maintain strong attachment during processing and provide easy removal after heat bending.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient peeling of the protective film from the resin substrate without adhering to the mold, maintaining the appearance of the substrate and improving productivity in producing lenses and other heat-bent products.
Implementation Method 1
a second layer which is positioned on the pressure sensitive adhesive layer side, contains a thermoplastic resin, and has a melting point of lower than 120° C.
Implementation Method 2
a pressure sensitive adhesive layer which is positioned between the base material layer and the resin substrate and is adhered to the resin substrate
Data Source
AI summary
A protective film 10 of the present invention is used by being attached to a resin substrate 21 at the time of performing heat bending on the resin substrate 21 while heating the resin substrate 21. The protective film 10 includes a base material layer and a pressure sensitive adhesive layer which is positioned between the base material layer and the resin substrate 21 and is adhered to the resin substrate 21. The base material layer is formed of a laminate having a first layer which is positioned on the opposite side of the pressure sensitive adhesive layer, contains a thermoplastic resin, and has a melting point of 150° C. or higher and a second layer which is positioned on the pressure sensitive adhesive layer side, contains a thermoplastic resin, and has a melting point of lower than 120° C.