Capacitive Touch Screen Ink Washout Prevention via Injection Compression Molding
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Solution Overview
Problem
Existing methods of injection molding for polycarbonate articles often result in ink washout due to high temperature and pressure, leading to visual and electrical failures, which complicates the production of articles with capacitive touch parts.
Innovation Solution
A polymeric article is produced using a first polymeric layer with an ink layer positioned between two sub-layers, where the second polymeric layer is formed via injection compression molding, reducing ink washout by maintaining a gap during the injection stage and using a lower pressure, allowing the ink layer to remain intact between the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard injection molding is used to produce polycarbonate articles with capacitive touch parts, then production efficiency is maintained, but ink washout occurs due to high temperature and pressure causing visual and electrical failures
Solution Approach 1:
The ink layer is applied to the polycarbonate substrate before the injection molding process begins. The substrate is prepared with the ink layer in advance, and then the molding process is performed around it. This preliminary positioning allows the ink layer to be protected during molding without requiring post-processing adjustments.
Solution Approach 2:
A release layer or protective coating is introduced as an intermediary between the ink layer and the injected polycarbonate resin. This intermediary layer prevents direct contact between the hot resin and the ink, eliminating washout while maintaining adhesion. The intermediary acts as a buffer that protects the sensitive ink layer during the high-pressure injection process.
2Manufacturing precision
If high pressure is applied during injection molding to ensure proper filling, then molding completeness is improved, but ink washout increases causing visual and electrical failures
Solution Approach 1:
A protective release layer is positioned between the injected resin and the ink layer to act as a pressure buffer. This intermediary absorbs and distributes the injection pressure, preventing concentrated force from washing out the ink while still allowing complete mold filling. The release layer maintains structural integrity under pressure while protecting the ink layer.
Solution Approach 2:
The injection process parameters are modified to use lower pressure and potentially higher temperature, or a multi-stage injection process is employed where initial filling occurs at low pressure followed by secondary filling. This parameter adjustment reduces the mechanical stress on the ink layer while ensuring complete mold cavity filling through extended injection time or multiple passes.
3Ease of manufacture
If high temperature is used during injection molding to ensure resin flow, then resin fillability is improved, but ink washout occurs due to thermal degradation
Solution Approach 1:
A thermally resistant release layer or protective coating is applied over the ink layer before injection molding. This intermediary layer has high thermal stability and acts as a heat barrier, protecting the temperature-sensitive ink from direct exposure to the hot molten resin. The release layer withstands the injection temperature while preventing thermal degradation of the ink, maintaining both electrical and visual properties.
4Quantity of substance
If the ink layer is positioned close to the injection gate for efficient material use, then material efficiency is improved, but ink washout risk increases at the gate area
Solution Approach 1:
A protective release layer is applied specifically at the injection gate area where the ink layer is positioned close to the gate for material efficiency. This localized intermediary protection allows the ink to remain near the gate for efficient resin flow initiation while the release layer prevents the high-velocity resin jet from washing out the ink at this critical location.
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
This method prevents ink washout, enabling the production of polycarbonate articles with capacitive touch parts without visual or electrical failures, simplifying manufacturing and reducing costs by allowing a continuous polymeric layer and providing structural protection.
Implementation Method 1
a second polymeric layer is formed upon the ink layer via injection compression molding
Implementation Method 2
a second polymeric layer is formed upon the ink layer via injection compression molding
Data Source
AI summary
According to one or more embodiments, a polymeric article includes a first polymeric layer defining a first portion and a second portion, the first portion having a first side and a second side opposing the first side, the first side being exposed to atmospheric air, and an ink layer and a second polymeric layer, the ink layer being positioned between the second polymeric layer and the second portion of the first polymeric layer.