Multilayer Propylene Resin Sheet for IV Bag Sterilization
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Solution Overview
Problem
Current packaging materials for IV bags face challenges in achieving a balance between heat resistance, transparency, flexibility, and impact resistance, particularly at low temperatures, and struggle with harsh heat-sealing conditions, leading to potential cracking and bursting.
Innovation Solution
A multilayer propylene resin sheet with specific layer compositions, including a propylene resin composition in the inner layer and a propylene resin in the outer layer, optimized for heat resistance, flexibility, and impact resistance, using propylene-α-olefin random copolymers, ethylene-α-olefin copolymers, and propylene resins with tailored melting points and melt flow rates to prevent thinning and sticking during heat sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyethylene resin is used primarily for IV bags, then flexibility and impact resistance are improved, but heat resistance deteriorates causing deformation at sterilization temperature
Solution Approach 1:
The IV bag is divided into multiple layers with different resin compositions. The outer layer uses polyethylene for flexibility and impact resistance, while the inner layer uses polypropylene for heat resistance. This segmentation allows each layer to fulfill its specific functional requirement without compromising the other.
Solution Approach 2:
The invention employs a composite multilayer structure combining polyethylene and polypropylene resins. This composite material approach integrates the advantages of both resins: polyethylene provides flexibility and impact resistance, while polypropylene provides heat resistance, creating a material that satisfies all performance requirements simultaneously.
2Temperature
If polypropylene resin is used primarily for IV bags, then heat resistance is improved, but impact resistance at low temperatures deteriorates
Solution Approach 1:
The multilayer structure segments the functional requirements: the inner layer uses polypropylene to provide heat resistance during sterilization, while the outer layer uses polyethylene to provide impact resistance at low temperatures. This segmentation resolves the contradiction by assigning each resin to the layer where it performs best.
Solution Approach 2:
The composite multilayer structure combines polypropylene and polyethylene in specific ratios and configurations. This allows the material to exhibit both heat resistance from polypropylene and low-temperature impact resistance from polyethylene, overcoming the limitations of using either resin alone.
3Strength
If elastomeric component is added to polypropylene to improve flexibility and impact resistance, then these properties are improved, but heat resistance deteriorates and transparency worsens
Solution Approach 1:
Instead of adding elastomeric components to polypropylene (which degrades heat resistance and transparency), the invention extracts the flexibility and impact resistance functions and assigns them to the polyethylene outer layer. This separation maintains the heat resistance and transparency of the polypropylene inner layer while achieving the desired mechanical properties through the multilayer structure.
Solution Approach 2:
The invention uses a composite multilayer structure where polyethylene serves as the elastomeric component provider in the outer layer, while polypropylene maintains its heat-resistant core function in the inner layer. This composite approach avoids the degradation issues associated with blending elastomers into polypropylene.
4Strength
If harsh heat sealing conditions are applied to achieve sufficient fusion, then welding strength is improved, but film thickness decreases and sticking to sealing bar occurs
Solution Approach 1:
The heat sealing process applies local quality control by using different sealing parameters for different layers. The outer polyethylene layer is sealed at lower temperatures and shorter durations to prevent excessive melting and thinning, while the inner polypropylene layer provides structural support. This localized optimization maintains welding strength while preventing film thinning and sticking.
Solution Approach 2:
The multilayer structure segments the heat sealing function: the outer layer is designed for easy sealing with minimal heat exposure to prevent sticking and thinning, while the inner layer provides structural integrity. This segmentation allows optimization of sealing conditions for each layer's specific requirements.
Data Source
AI summary
The invention discloses a multilayer propylene resin sheet and a heat-treatable packaging material which have an excellent transparency, flexibility and very-low-temperature impact resistance, and which reduce the thickness variation during lamination, suppress appearance defects such as interfacial roughness and mitigate thinning during fabrication. The multilayer propylene resin sheet is composed of at least two layers, which are (1) an inner layer and (2) an outer layer. The inner layer (1) is made of a resin composition containing 40 to 89 wt% of a specific propylene resin composition (A), 10 to 40 wt% of a specific ethylene-α-olefin copolymer (B), and 1 to 20 wt% of a specific propylene resin (C). The outer layer (2) is made of a specific propylene resin composition.