Polypropylene Bottle Heat Conditioning for Hot Fill
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Solution Overview
Problem
Conventional injection stretch blow molding processes for PET bottles are limited in producing complex shapes and cannot withstand high temperatures in hot fill processes, requiring expensive heat-set manufacturing and resulting in costly production.
Innovation Solution
A single-step injection stretch blow molding method using a heat-conditioning step with a plurality of heat pots to form polypropylene bottles, allowing for complex shapes and high-temperature resistance without the need for vacuum panels or expensive machinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional injection stretch blow molding is used for PET bottles, then complex geometric shapes can be formed, but the bottles cannot withstand high temperatures in hot fill processes
Solution Approach 1:
The patent changes the material parameter from PET to polypropylene, which has inherently higher temperature resistance. The polypropylene preform is processed through injection stretch blow molding to create bottles that can withstand hot fill temperatures up to 212°F while maintaining the capability to form complex geometric shapes.
Solution Approach 2:
The patent applies a heat conditioning step before the blow molding process. The polypropylene preform is heated to a specific temperature range to condition the material, making it more deformable during the subsequent blow molding process. This preliminary heating action enables complex shape formation while the material's inherent properties ensure temperature resistance in the final product.
2Temperature
If heat-set injection stretch blow molding is used for PET bottles to withstand hot fill, then temperature resistance is improved, but production cost increases significantly
Solution Approach 1:
The patent uses standard polypropylene material with a single-step injection stretch blow molding process instead of expensive heat-set PET machinery. This approach uses more common, less expensive equipment and material combinations to achieve the same hot fill temperature resistance, significantly reducing production costs while maintaining the required temperature withstand capability.
Solution Approach 2:
The patent extracts the heat-set conditioning step from the manufacturing process. By using polypropylene's inherent temperature resistance properties and a simple pre-heating condition, the complex and expensive heat-set process required for PET is eliminated, reducing equipment costs and simplifying manufacturing while still achieving bottles that can withstand hot fill temperatures.
3Ease of manufacture
If extrusion blow molding is used for polypropylene bottles, then production cost is reduced, but complex geometric shapes cannot be formed and port lines appear on threads
Solution Approach 1:
The patent merges the injection molding and stretch blow molding processes into a single integrated injection stretch blow molding operation. This combined process uses polypropylene material to simultaneously achieve complex geometric shape formation, eliminate port lines on threads, and maintain cost-effectiveness, resolving the limitations of separate extrusion and injection processes.
4Shape
If polypropylene preform is heated uniformly, then material becomes too soft and loses structural integrity, but if not heated enough, complex shapes cannot be formed
Solution Approach 1:
The patent applies differential heating to different zones of the polypropylene preform. The body portion of the preform is heated to a higher temperature to enable complex shape formation, while the neck portion is maintained at a lower temperature to preserve structural integrity and thread formation capability. This localized temperature control allows simultaneous achievement of shape complexity and structural 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
The method enables the production of polypropylene bottles that can hold liquids at temperatures up to 212°F without deformation, reducing production costs and allowing for more complex geometries and improved sealing, while maintaining clarity and deformability.
Implementation Method 1
heating the preform vessel at a plurality of positions on the preform vessel with a plurality heat pots, wherein each of the heat pots is configured to heat a corresponding one of the plurality of positions on the preform vessel by raising a temperature of the heat pot to a respective temperature
Implementation Method 2
blowing air through the nozzle into the heated preform vessel, wherein the blown air is at a second temperature and expands the heated preform vessel to couple the expanded preform vessel with the internal surface of the cavity
Data Source
AI summary
A method of manufacturing a polypropylene vessel using a single-step injection stretch blow molding machine using a heat-conditioning step. The method may include providing a chemical composition comprising polypropylene, forming a preform vessel of the chemical composition in a second shape, heating the preform vessel at a plurality of positions on the preform vessel with heat pots, wherein each of the heat pots is configured to heat a corresponding one of the plurality of positions on the preform vessel by raising a temperature of the heat pot to a respective temperature, wherein each respective temperature of each of the heat pots is different from another respective temperature of another of the heat pots, wherein the temperatures of the heat pots are based on the desired first shape of the product. The method may include forming, from the heated and expanded preform, a second vessel in a desired first shape.