Plasma Diffuser Coating Design to Reduce Substrate Discolouration
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Solution Overview
Problem
Plasma coatings often cause unwanted discolouration, particularly on dark substrates such as black, grey, and blue surfaces, leading to issues like darkening or rainbow-like effects, which are undesirable in consumer products.
Innovation Solution
A plasma diffuser is used to diffuse the plasma during the coating process, ensuring a more uniform plasma distribution and reducing discolouration by placing diffuser material between the substrates and electrodes, maintaining coating performance while minimizing colour changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma coating is applied to dark substrates, then functional coating performance is achieved, but discolouration and rainbow effects occur on the substrate surface
Solution Approach 1:
A plasma diffuser is introduced as an intermediary component between the plasma source and the substrate. The diffuser material (positioned at 5-50mm from the substrate) mediates the plasma-coating interaction by scattering plasma species, which reduces direct plasma exposure to dark substrates and thereby minimizes discolouration while maintaining coating functionality
Solution Approach 2:
The invention changes the physical parameters of plasma delivery by introducing a diffuser that alters plasma species distribution. This modifies the energy deposition pattern on the substrate, reducing localized heating and chemical reactions that cause discolouration, while still achieving adequate coating coverage through scattered plasma flux
2Productivity
If high plasma density is used for efficient coating deposition, then coating speed increases, but discolouration effect becomes more pronounced
Solution Approach 1:
The plasma diffuser acts as a mediator that decouples plasma density from substrate exposure intensity. High plasma density can be maintained in the chamber for productivity, while the diffuser scatters the plasma flux to reduce peak exposure on the substrate, thereby preventing discolouration even during high-rate deposition
Solution Approach 2:
The diffuser creates local variations in plasma flux distribution across the substrate surface. By scattering plasma species, it ensures more uniform local exposure conditions, preventing localized high-density plasma regions that would cause intense discolouration while maintaining overall coating efficiency
3Reliability
If plasma coating is applied to high-gloss surfaces, then functional properties are added, but the glossy appearance deteriorates with rainbow-like discolouration
Solution Approach 1:
The plasma diffuser serves as an intermediary that softens the plasma-substrate interaction. By scattering plasma species before they reach the high-gloss surface, it prevents concentrated energy deposition that would cause localized chemical changes and rainbow effects, thereby preserving the surface appearance while adding functional coating properties
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 plasma diffuser significantly reduces or eliminates discolouration on dark surfaces and high-gloss substrates, maintaining the performance of the coatings in terms of oil repellency and washability, allowing for broader application of plasma coatings in consumer products.
Implementation Method 1
The plasma diffuser comprises a plasma diffuser material placed in said plasma chamber... for homogenizing a plasma density nearby said substrate
Implementation Method 2
deposit plasma coatings, preferably by plasma polymerization and preferably at low pressure, onto substrates sensitive to colour change
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 1G~1H
AI summary
The present invention concerns a method for at least partially preventing discolouration of a substrate by a plasma coating process, by diffusing a plasma prior to and/or during depositing of said plasma on said substrate to form a coating. The present invention also concerns a plasma coating apparatus comprising a plasma diffuser for homogenizing a plasma density nearby a substrate to be coated.