Soft X-Ray Sterilization of Plastic Parisons
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for aseptic moulding of plastic containers face challenges such as longer processing times, increased chemical consumption, disposal of chemical residues, and interference with pre-blow heating due to sterilization methods, and radiation sterilization methods either require extensive time or bulky shielding.
Innovation Solution
A method and apparatus that uses a radiation treatment unit with a shielding tunnel for soft X-ray sterilization between the heating and blowing units, allowing for simultaneous sterilization and maintaining overall processing time and dimensions unchanged, utilizing soft X-rays with energies below 60 keV for efficient penetration and reduced treatment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical sterilization is used on moulded containers, then sterilization is achieved, but processing time increases and chemical consumption increases
Solution Approach 1:
The patent applies preliminary action by sterilizing the parison before it is moulded into the final container shape. This is achieved by introducing a sterilizing substance into the mould cavity that contacts the parison during the moulding process itself, rather than sterilizing the finished container separately. This preliminary sterilization reduces subsequent processing time while maintaining effectiveness.
Solution Approach 2:
The invention segments the sterilization process from the final container by sterilizing the parison (pre-form) rather than the completed container. Since the parison has a smaller surface area than the fully expanded container, this segmentation allows faster, more efficient sterilization with less chemical consumption while achieving the same reliability outcome.
2Reliability
If sterilization is performed before heating, then sterilization is achieved, but the temperature profile becomes incorrect
Solution Approach 1:
The patent merges the sterilization step with the heating and moulding process by introducing the sterilizing substance into the heated mould cavity where the parison is already being formed. This combination allows sterilization to occur concurrently with thermal processing, achieving both sterilization effectiveness and correct temperature profile without sequential delays.
Solution Approach 2:
The sterilizing substance is introduced into the mould cavity before the parison is fully formed and while heating is occurring. This preliminary introduction of the sterilizing agent allows it to act on the parison during the thermal processing phase, ensuring both sterilization and proper temperature profile are achieved simultaneously.
3Reliability
If radiation sterilization with high penetration is used, then sterilization depth is improved, but treatment time increases significantly
Solution Approach 1:
The patent changes the energy parameter of the radiation by using microwave radiation at specific frequencies (2.45 GHz or 5.8 GHz) that provide optimal penetration depth for typical parison thicknesses. This parameter optimization achieves sufficient sterilization penetration without the excessive treatment times associated with lower-energy radiation methods.
Solution Approach 2:
The microwave sterilization is applied in periodic pulses rather than continuous exposure. The parison is subjected to intermittent microwave irradiation during the moulding cycle, achieving cumulative sterilization effect within the required time frame while allowing brief intervals for heat distribution and process integration.
4Loss of time
If low-energy radiation is used for sterilization, then treatment time is reduced, but penetration capacity into the material is limited
Solution Approach 1:
The patent optimizes the radiation energy parameter by selecting microwave frequencies (2.45 GHz or 5.8 GHz) that provide the right balance between penetration depth and treatment speed for the specific parison geometry. This parameter tuning achieves both rapid treatment and sufficient penetration without requiring high-energy radiation that would increase processing time.
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 enables efficient sterilization within the existing processing time frame, reduces chemical residue issues, and minimizes apparatus dimensions and complexity, while maintaining the thermal profile and reducing shielding needs.
Implementation Method 1
a radiation treatment unit (5) for treating the heated parisons (4) with radiation, in particular with soft X-rays
Implementation Method 2
directly ionizing radiation, such as electrons or other accelerated charged particles; indirectly ionizing radiation, such as X-rays or γ-rays
Implementation Method 3
a unit (3) for heating parisons (4) of plastic material
Implementation Method 4
the parisons are conveyed to a heating unit where the sterilization thereof is completed
Data Source
AI summary
Method for aseptic molding of containers (2) of plastic material, comprising the steps of: heating parisons (4) of plastic material; sterilizing the parisons (5) by means of soft X-rays inside an advancing tunnel (7) after heating them and before molding them; blowing the heated and sterilized parisons (4) in such a way as to obtain the containers.