SiOxCy Tie Coating for Low Oxygen Transmission Rate
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Solution Overview
Problem
Current SiOx barrier coatings on thermoplastic pharmaceutical packaging are prone to etching by aqueous contents with high pH values, reducing their barrier efficacy and shelf life, and are not suitable for oxygen-sensitive drugs due to high gas permeation rates, while existing solutions fail to maintain a consistent vacuum in evacuated blood sample collection tubes.
Innovation Solution
A method involving a tie coating of SiOxCy applied by PECVD, followed by a SiOx barrier coating, and optionally a pH protective SiOxCy coating, all while maintaining a partial vacuum to reduce gas permeation and protect the barrier coating from pH-induced damage, ensuring a longer shelf life and maintaining the vacuum level in evacuated blood collection tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SiOx barrier coating is applied to thermoplastic pharmaceutical packaging, then gas permeation rate is reduced, but the coating is etched by aqueous contents with high pH values, reducing barrier efficacy
Solution Approach 1:
The coating system is divided into three distinct layers: a tie coating layer (SiOxCy) providing adhesion to the thermoplastic substrate, a barrier coating layer (SiOx) providing oxygen barrier functionality, and a pH protective coating layer (SiOxCy) protecting the barrier layer from etching. This segmentation allows each layer to perform its specific function without compromising the others.
Solution Approach 2:
The pH protective coating layer acts as an intermediary between the aqueous contents and the SiOx barrier coating layer, preventing direct contact and etching of the barrier layer while allowing the barrier layer to maintain its oxygen barrier efficacy.
2Strength
If plastic is used for pharmaceutical packaging, then dimensional tolerance and breakage resistance are improved, but gas permeation rate increases significantly
Solution Approach 1:
The packaging system combines thermoplastic material with a multi-layer coating system. The thermoplastic provides mechanical strength and breakage resistance, while the coating layers (particularly the SiOx barrier layer) provide low gas permeation rate. This composite structure achieves both desired properties.
3Reliability
If multiple coating layers are applied to the vessel, then barrier efficacy and pH protection are improved, but manufacturing complexity increases
Solution Approach 1:
The tie coating and pH protective coating layers (both SiOxCy composition) are applied in separate steps but with similar process parameters, allowing the manufacturing process to be optimized and streamlined. The barrier coating layer (SiOx) is applied between them with different parameters. This merging of similar process steps reduces overall complexity compared to having three completely different coating processes.
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 coated vessels exhibit a lower gas permeation rate and extended shelf life, maintaining at least 90% of the draw volume capacity over time, effectively protecting the contents from atmospheric gases and pH-induced erosion.
Implementation Method 1
a tie coating or layer 289 of SiOxCy is applied by a tie PECVD coating process
Implementation Method 2
A barrier coating or layer 288 of SiOx, wherein x is from 1.5 to 2.9 as determined by XPS, between the tie coating or layer 289 and the lumen 212
Implementation Method 3
A partial vacuum is drawn in the lumen 212. While maintaining the partial vacuum unbroken in the lumen 212
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Processing an evacuated blood sample collection tube or other vessel by plasma enhanced chemical vapor deposition to apply a tie coating or layer (289), a barrier coating or layer (288), and optionally one or more additional coatings or layers. The tie coating or layer of SiOxCy is applied under partial vacuum and, while maintaining the partial vacuum unbroken in the lumen, the barrier coating or layer is applied. Then optionally, while maintaining the partial vacuum unbroken in the lumen, a pH protective coating or layer of SiOxCy can be applied. As a result of this processing, a coated vessel is produced having a lower gas permeation rate constant into the lumen than a corresponding vessel made by the same process except breaking the partial vacuum in the lumen between applying the tie coating or layer and applying the barrier coating or layer. Retention features are also described for keeping the vessels stoppered during exposure to reduced ambient pressure.