Dual-Layer Plasma Polymerized Coating for Stain-Resistant Polymers
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Solution Overview
Problem
Existing methods for depositing silicon oxide (SiOx) or SiOxCHz layers on polymer substrates, such as polypropylene, using Plasma Enhanced Chemical Vapor Deposition (PECVD) face challenges with adhesion, wash resistance, and staining, particularly when exposed to dishwasher temperatures, and fail to maintain transparency and flexibility.
Innovation Solution
A method involving a first and second plasma polymerized tetramethylsilane coating with specific oxygen ratios and deposition times, creating SiOxCHz layers with thicknesses between 1-15 nanometers and 10-100 nanometers respectively, to enhance adhesion, wash resistance, and transparency, while maintaining flexibility and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon oxide coating is deposited on polymer substrate using PECVD, then gas barrier performance is improved, but adhesion and wash resistance deteriorate
Solution Approach 1:
The coating is divided into multiple layers with different compositions and functions. The first layer (1-15 nm) provides adhesion to the polymer substrate, while the second layer (10-100 nm) provides the gas barrier function. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between adhesion and barrier performance.
Solution Approach 2:
The invention uses composite material structure with at least two different silicon oxide layers having different compositions (different SiOx ratios) and thicknesses. The composite structure combines the adhesion benefits of one composition with the barrier benefits of another, simultaneously achieving both strong adhesion and excellent gas barrier performance.
2Reliability
If coating thickness is increased to improve barrier properties, then gas impermeability is improved, but transparency and flexibility deteriorate
Solution Approach 1:
The total coating thickness is segmented into multiple thin layers rather than one thick layer. The first layer is very thin (1-15 nm) to maintain transparency and flexibility, while the second layer (10-100 nm) provides the necessary gas barrier. The segmented structure achieves barrier performance without sacrificing optical properties.
Solution Approach 2:
The invention uses ultra-thin film structures (total thickness 10-100 nm) that maintain the flexibility of the polymer substrate while providing gas barrier functionality. The thin film approach ensures transparency is preserved while achieving the required barrier performance through multiple layers with optimized compositions.
3Device complexity
If single-layer coating is applied to reduce manufacturing complexity, then process simplicity is improved, but staining resistance and wash resistance deteriorate
Solution Approach 1:
The coating process is segmented into sequential deposition steps creating distinct layers. The first layer (1-15 nm) with lower SiOx ratio provides staining resistance by creating a hydrophilic surface, while the second layer (10-100 nm) with higher SiOx ratio provides the gas barrier. This segmented approach prevents staining while maintaining manufacturing feasibility.
Solution Approach 2:
The invention applies composite material principles by depositing at least two different silicon oxide layers with different compositions on the polymer substrate. The composite structure combines the staining resistance of one composition with the barrier properties of another, achieving both stain resistance and gas impermeability through a multi-layer composite coating.
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 method results in polymer articles with significantly reduced staining tendencies, excellent wash resistance, and transparency, capable of withstanding dishwasher cycles and exposure to refrigerators, freezers, and microwave ovens, with improved steam resistance and barrier properties against odorants, flavorants, and water vapor.
Implementation Method 1
A plasma treatment is a chemical process wherein a gaseous compound in a given volume is decomposed under reduced atmosphere by an electrical glow discharge resulting in the coating of a thin film on the walls of a container
Implementation Method 2
Plasma Enhanced Chemical Vapor Deposition (hereinafter referred to as PECVD) is used for depositing a variety of thin films
Implementation Method 3
PECVD uses electrical energy to generate a glow discharge in which the energy is transferred into a gas mixture. This transforms the gas mixture into reactive radicals, ions, neutral atoms and molecules and other excited species
Data Source
Figure 1
AI summary
A polymer article having a thin coating on at least one of its side is produced. The coating comprises a first coating of SiOxCyHz which is a plasma polymerized tetramethylsilane deposited on the surface on the polymer article, the x value being between 0 and 1.7, the y value being between 0.5 and 0.8, the z value being between 0.35 and 0.6 for said first SiOxCyHz coating and a second coating of SiOxCyHz which is a plasma polymerized tetramethylsilane deposited on the surface on said first coating, the x value being between 1.7 and 1.99, the y value being between 0.2 and 0.7, the z value being between 0.2 and 0.35 for said second SiOxCyHz coating. An oxidizing gas such as oxygen is used at least for the deposition of the second coating. The method is suitable to produce washable containers having reduced tendency of being stained.