Two-Phase Injection Molding for Additive-Free Scrap Recovery
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Solution Overview
Problem
Existing methods for manufacturing wide mouth plastic blow-molded containers for food packaging result in significant scrap material with additives, which poses challenges for reprocessing and reuse due to cost, clarity issues, and layer delamination problems.
Innovation Solution
A two-phase injection system is used, where virgin PET is injected in the first phase and PET with additives in the second phase, allowing the scrap material from the dome or moil section to be free of additives, enabling its reuse without processing complications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single stage injection mold equipment is used to manufacture blow-molded containers, then the manufacturing process is simplified and productivity is improved, but significant scrap material with additives is generated causing reprocessing difficulties
Solution Approach 1:
The injection molding process is segmented into two phases: first injecting virgin PET resin to form the dome/moil section, then injecting PET with additives to form the container body. This segmentation allows the scrap material (dome/moil) to be free of additives, making it suitable for reprocessing while maintaining container functionality.
Solution Approach 2:
Different material qualities are applied to different parts of the preform: virgin PET (higher quality) is used for the dome/moil section that becomes scrap, while PET with additives (lower quality) is used for the container body. This local differentiation optimizes both reprocessing capability and product performance.
2Reliability
If PET with additives is injected into the preform, then the container achieves required functional properties, but the scrap material becomes difficult to reprocess due to additives causing cost, clarity issues, and layer delamination
Solution Approach 1:
The preform injection is segmented into two phases where additives are only introduced in the second phase for the container body portion, keeping the dome/moil section (future scrap) free of additives. This enables easy reprocessing of scrap while maintaining container functionality.
Solution Approach 2:
Additives are locally applied only to the container body section where they are needed for functionality, while the dome/moil section remains free of additives to facilitate easy reprocessing without clarity issues or layer delamination.
3Ease of manufacture
If virgin PET is used throughout the preform, then scrap material can be easily reprocessed, but the container body lacks necessary functional additives
Solution Approach 1:
The injection process is divided into two phases: first phase uses virgin PET for the dome/moil section, second phase adds PET with additives for the container body. This ensures scrap from the first phase is easy to reprocess while the second phase provides necessary functional properties.
Solution Approach 2:
The virgin PET is injected first to form the dome/moil section that will become scrap, establishing a foundation of easily reprocessible material before introducing additives for the container body portion.
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 approach minimizes scrap material costs and avoids reprocessing issues, ensuring the scrap can be fully utilized without affecting the quality of virgin PET, thus reducing waste and maintaining container integrity.
Implementation Method 1
injection molding a preform using a two phase injection system. A first phase of the two phase injection system includes injecting a first material into the preform and a second phase of the two phase injection system includes injecting a second material into the preform
Implementation Method 2
the preform is transferred to a blow station to form the container and removed from the machine
Implementation Method 3
Prior to being formed into containers, preforms are softened and transferred into a mold cavity
Data Source
AI summary
A method for manufacturing a food and/or beverage packaging container is provided. The method includes injection molding a preform using a two phase injection system. A first phase of the two phase injection system includes injecting a first material into the preform and a second phase of the two phase injection system includes injecting a second material into the preform. The method further includes disposing the preform in a mold, blow molding the preform into an intermediate article having a length, a diameter and side walls having a wall thickness, and trimming the intermediate article to form a finished container having a wide mouth neck. Systems and finished products are disclosed.