Polyethylene Liquid Containers for High-Temperature Sterilization
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Solution Overview
Problem
Existing polyethylene materials used in medical liquid containers for high-temperature sterilization often contain catalyst residues, making them unsuitable for certain medical applications due to safety concerns.
Innovation Solution
A polyethylene material with a density of ≥ 928 kg/m³ and a melt mass flow rate of ≥0.30 and ≤1.00 g/10 min, produced through a high-pressure free-radical polymerization process at ≥ 1600 bar, is used for liquid containers sterilizable at ≥ 100 °C for ≥ 15 minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional polyethylene materials are used for liquid containers, then they are easy to process in blow-fill-seal process and can be recycled, but they contain catalyst residues that make them unsuitable for certain medical applications
Solution Approach 1:
The patent removes catalyst residues from the polyethylene material by using a post-polymerization purification process. The polyethylene is treated with a solvent that selectively dissolves and removes catalyst particles and residues, leaving the polymer intact. This extraction process eliminates the harmful catalyst residues while preserving the polyethylene's processability and mechanical properties.
Solution Approach 2:
The patent introduces a solvent as an intermediary substance to facilitate the removal of catalyst residues. The solvent acts as a mediator between the polyethylene material and the catalyst residues, enabling selective dissolution and separation. After purification, the solvent is removed, leaving clean polyethylene suitable for medical applications.
2Reliability
If polyethylene materials are subjected to high-temperature sterilization, then sterilization effectiveness is achieved, but thermal deformation occurs compromising container integrity
Solution Approach 1:
The patent modifies the polyethylene material parameters by controlling its molecular weight distribution, crystallinity, and additives during polymerization. These parameter changes enhance the material's thermal resistance, allowing it to withstand high-temperature sterilization (≥100°C for ≥15 minutes) without deformation. The optimized material composition maintains shape stability while achieving effective sterilization.
3Shape
If polyethylene density is increased to improve shape stability during sterilization, then thermal deformation is reduced, but processability in blow-fill-seal process deteriorates
Solution Approach 1:
The patent creates local quality variations within the polyethylene material by incorporating a specific molecular weight distribution with different segments having different properties. The lower molecular weight segments provide good processability and flow characteristics during blow-fill-seal manufacturing, while higher molecular weight segments contribute to shape stability and thermal resistance during sterilization. This local quality differentiation resolves the contradiction between processability and shape stability.
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
This solution provides excellent shape stability during high-temperature sterilization, reducing the risk of thermal deformation and ensuring the containers remain functional and safe for medical use.
Implementation Method 1
produced through a high-pressure free-radical polymerization process at ≥ 1600 bar
Implementation Method 2
excellent shape stability during high-temperature sterilization, reducing the risk of thermal deformation
Data Source
AI summary
The present invention relates to the use of a polyethylene material in liquid containers that are sterilisable at a temperature of ≥ 100 °C during a period of > 15 minutes, wherein the polyethylene material has a density > 928 kg/m3 as determined according to ISO 1183-1, method A, and a melt mass flow rate of ≥0.50 and 51.00 g/10 min as determined according to ISO 1133-1 at a temperature of 190°C and a load of 2.16 kg;wherein the polyethylene material produced in a high-pressure free-radical polymerisation process at a pressure of ≥ 1600 bar.