Composite Storage Bag Lap Seams for Cryogenic Leak Protection
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Solution Overview
Problem
Current cryopreservation bags used for storing biologics face issues with durability at freezing temperatures, leakage, and plastic extractables interacting with drug substances, particularly at the ends and corners of the bags.
Innovation Solution
The development of a storage bag with a composite structure featuring a higher melting polymer inner surface and a lower melting polymer outer surface, where lap seams are formed using a composite sheet with a non-melt-processable and melt-processable polymer sides, enhancing durability and reducing leakage by covering joints at the ends and corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer plastic bag is used for cryopreservation, then the bag is simple to manufacture, but the bag exhibits poor durability and leakage at freezing temperatures
Solution Approach 1:
The patent applies composite materials by constructing the storage bag from multiple polymer layers with distinct functions: an inner layer (e.g., polyolefin) that remains flexible at cryogenic temperatures, an intermediate layer (e.g., polyester or polyamide) providing mechanical strength and barrier properties, and an outer layer (e.g., polypropylene or polyethylene) offering protection during handling. This multi-layer composite structure resolves the contradiction by combining materials with complementary properties to achieve both durability at freezing temperatures and manageable structural complexity.
Solution Approach 2:
The patent applies local quality by differentiating the properties of different regions and layers of the bag. The inner layer is specifically designed with low glass transition temperature to maintain flexibility at cryogenic temperatures, while the intermediate layer provides structural rigidity, and the outer layer offers environmental protection. This localized optimization of material properties throughout the composite structure enables the bag to withstand freezing conditions without excessive overall complexity.
2Object-affected harmful factors
If conventional plastic bags are used for storage, then the bags are easy to manufacture, but plastic extractables interact with drug substances
Solution Approach 1:
The patent applies the extraction principle by removing or eliminating the problematic extractable components from the bag structure. The inner layer is specifically selected from polyolefins or other materials with proven low extractable content, effectively extracting the harmful interaction component from the system. This allows the bag to be manufactured with controlled material composition that prevents drug-substance interaction while maintaining ease of production through established manufacturing processes for multi-layer films.
Solution Approach 2:
The patent applies the intermediary principle by introducing an intermediate barrier layer between the stored drug substance and the outer environment. This intermediate layer (polyester or polyamide) acts as a mediator that prevents extractables from the outer layers from contacting the therapeutic compound, while still allowing the bag to be manufactured using standard lamination and sealing processes.
3Reliability
If lap seams are formed at bag ends and corners, then leakage is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the tube structure with extended ends before the final sealing process. The tube is constructed with lengthwise seams that extend beyond the intended bag ends, creating preliminary overlap regions that facilitate subsequent lap seam formation. This preliminary preparation enables reliable leakage protection at corners and ends while simplifying the actual sealing process, as the overlapping sections are already in position for thermal or ultrasonic welding.
Solution Approach 2:
The patent applies phase transitions by utilizing thermal melting and solidification of the polymer materials during the lap seam formation process. The sealing process involves heating the overlapping edges above the polymer's melting point, allowing them to fuse, then cooling to solidify the bond. This phase transition mechanism creates strong, leakage-proof seams at critical locations without requiring complex mechanical fastening systems.
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 solution provides enhanced leak protection and improved durability of the storage bags, minimizing interactions between plastic components and therapeutic compounds, thus maintaining the stability of biologics during cryopreservation.
Implementation Method 1
forming a composite tube having an inner surface comprising a higher melting polymer, an outer surface comprising a lower melting polymer
Implementation Method 2
folding the composite sheet over the joint such that the second side comprising a melt-processable polymer engages the joint to form a lap seam over the joint
Data Source
AI summary
A storage bag configured to contain or that contains at least one therapeutic compound such as a viral vector and non-viral vector is provided. In one embodiment, the storage bag contains a viral vector and/or a non-viral vector containing genetic material. The storage bag has two edges and two ends including a first face and a second face integrally joined at the two edges of the bag and defining an inner surface and an outer surface forming the bag; the inner surface including a higher melting polymer, and the outer surface including a lower melting polymer; a joint at one of the ends; a discrete composite sheet having a first side including a higher melting polymer and a second side including a lower melting polymer folded over the joint with the first side including a lower melting polymer engaging the joint to form a lap seam over the joint.