Film-Covered Molded Article Substrate Surface Roughness Control
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Solution Overview
Problem
Conventional direct coating methods for automobile and household appliance parts result in inefficiencies due to multiple processing steps, environmental safety concerns, limited design diversity, and inadequate weather resistance, while decorative films with adhesive layers can develop blisters due to air trapped between the film and substrate, especially under high-temperature conditions.
Innovation Solution
Controlling the surface roughness of the substrate to a range of 3 to 20 μm ensures effective deaeration and adhesion, preventing air entrapment and blister formation, thereby maintaining the appearance and durability of molded articles even in severe environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a decorative film with an adhesive layer is applied to a molded article surface by vacuum forming, then the problems of workability, environmental safety, and design diversity are solved, but air remains between the film and substrate causing blisters that deteriorate appearance
Solution Approach 1:
The adhesive layer is designed with a porous structure containing numerous air bubbles, allowing trapped air to escape through the adhesive layer during film application, thereby preventing blister formation while maintaining good adhesion and workability
2Strength
If the adhesive layer is made smooth for good adhesion, then bonding strength improves, but air cannot escape causing blisters under high-temperature conditions
Solution Approach 1:
The adhesive layer incorporates a porous structure with air bubbles that provide escape paths for trapped air, enabling the layer to maintain both strong adhesion and reliability in high-temperature environments by allowing air to escape without compromising bonding strength
3Reliability
If communicating grooves or passages are provided in the adhesive layer for deaeration, then air can escape, but the film sinks in the grooves forming a concave-convex pattern on the surface
Solution Approach 1:
Instead of creating macroscopic grooves or passages that cause surface irregularities, the invention uses a microscopic porous structure with air bubbles distributed throughout the adhesive layer, enabling air escape while maintaining a smooth, flat surface appearance
Solution Approach 2:
The deaeration function is transitioned from a two-dimensional surface structure (grooves) to a three-dimensional volumetric structure (air bubbles distributed throughout the adhesive layer), allowing air escape without affecting surface flatness
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
The solution ensures a flawless appearance and enhanced durability of molded articles by eliminating air pockets and improving adhesion, maintaining the appearance and performance under high-temperature conditions.
Implementation Method 1
the film has an adhesive layer, the adhesive layer is in contact with the substrate
Data Source
AI summary
PURPOSE: The present invention provides a molded article which comprises a substrate whose surface is covered with a film, has good appearance, and does not deteriorate in the appearance even in severe environment where the article is actually used, such as high-temperature environment.CONSTITUTION: A molded article comprising a substrate whose surface is partially or wholly covered with a film, wherein the film has an adhesive layer, the adhesive layer is in contact with the substrate and the surface of the substrate, which surface is in contact with the adhesive layer, has a surface roughness (A) of 3 to 20 μm.