PICVD Passivation Layer for pH-Resistant Plastic Container Coatings
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Solution Overview
Problem
Current SiOx barrier layers applied to plastic containers using PECVD are not pH-resistant and degrade quickly when exposed to media with pH values above 5, leading to a reduced barrier effect and short shelf life of packaged products.
Innovation Solution
A composite material with a substrate coated by a barrier layer and a passivation layer, where the passivation layer is a non-polar organic top coat produced using PICVD, providing enhanced stability and resistance to etching, with specific intensity ratios and compositions optimized for SIMS and ATR measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PECVD is used to apply SiOx barrier layers to plastic containers, then the barrier effect against gas and liquid permeation is improved, but the layer stability deteriorates due to etching by pH values greater than or equal to 5
Solution Approach 1:
The patent applies a composite coating structure consisting of an inner barrier layer (SiOx) and an outer passivation layer (organic top coat). The barrier layer provides gas and liquid permeation resistance, while the passivation layer protects the barrier layer from etching by pH values greater than or equal to 5. This composite structure resolves the contradiction by combining materials with complementary properties - the inorganic SiOx layer for barrier performance and the organic passivation layer for chemical stability.
Solution Approach 2:
The organic passivation layer acts as an intermediary between the SiOx barrier layer and the external environment (beverage media). It shields the barrier layer from direct contact with pH-sensitive media, preventing etching while allowing the barrier layer to maintain its permeation resistance. The passivation layer serves as a protective mediator that enables the barrier layer to function effectively in pH ranges greater than or equal to 5.
2Reliability
If the barrier layer is exposed to media with pH values above 5, then the barrier effect is improved for gas and liquid permeation, but the shelf life deteriorates due to rapid etching and degradation
Solution Approach 1:
The composite coating system combines a SiOx barrier layer for permeation resistance with an organic passivation layer for chemical durability. This combination enables the coating to maintain both barrier effectiveness and long shelf life when in contact with pH-sensitive beverages, resolving the contradiction between immediate barrier performance and long-term durability.
Solution Approach 2:
The organic passivation layer is applied in advance to protect the SiOx barrier layer before exposure to pH-sensitive media. This preliminary protective action prevents etching and degradation from occurring, thereby extending the shelf life of the coated container while maintaining the barrier effect throughout the product's storage period.
3Productivity
If plastic containers are used for beverage packaging, then productivity and cost-effectiveness are improved, but the barrier effect deteriorates due to insufficient resistance to gas and liquid permeation
Solution Approach 1:
The patent applies a composite coating system (SiOx barrier layer plus organic passivation layer) to standard plastic containers. This enables inexpensive mass-produced plastics to achieve the same barrier properties as expensive special plastics, resolving the contradiction between cost-effectiveness and barrier performance. The coating allows regular plastic containers to effectively replace glass and specialized barrier plastics.
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 composite material maintains an effective barrier effect for at least six months at room temperature and up to three years at pH values up to 10, significantly extending the shelf life of products stored in plastic containers.
Implementation Method 1
plasma pulse-induced CVD coating (PICVD coating)
Implementation Method 2
chemical vapor phase deposition (CVD)
Implementation Method 3
plasma-assisted CVD coating (PECVD)
Data Source
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AI summary
The invention relates to a composite material (1) for containers and to a method for producing a composite material (1) that comprises a substrate (2) and a coating (3) applied to the substrate (2). The coating (3) comprises at least one first zone (31) facing the substrate (2) and at least one second zone (32) facing away from the substrate (2). The first zone (31) comprises a barrier layer (4). The invention aims at developing a coating which retains its barrier effect at least for six months at room temperature when in contact with media having a pH value higher than 5, in particular higher than 6.5. According to the invention, the second zone (32) comprises for that purpose a passivation layer (5).