Multilayer PET Container Preform for Additive-Free Trim Scrap
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Solution Overview
Problem
Existing plastic blow-molded containers face issues with scrap material containing additives that cause reprocessing complications, cost inefficiencies, and layer delamination, particularly at the trim point, which affects the reuse and processing of such materials.
Innovation Solution
A two-phase injection system is employed to form containers with specific layer configurations, where the inner and outer layers consist of virgin PET and additives are limited to a discrete layer that does not extend to the trim point, allowing the scrap material to be reused without additives, thus avoiding reprocessing issues and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives are included in the preform material to improve oxygen barrier performance and shelf life, then packaging protection is enhanced, but scrap material becomes contaminated with additives causing reprocessing complications and cost inefficiencies
Solution Approach 1:
The preform is divided into multiple injection phases creating distinct layers: a first layer without additives suitable for scraping, and second/third layers with oxygen scavenger additives for barrier performance. This segmentation allows scrap from the additive-free first layer to be reprocessed separately without contamination issues.
Solution Approach 2:
Different regions of the preform have different material compositions tailored to their specific functions. The first layer (near the sprue) is additive-free for easy reprocessing, while the second and third layers contain oxygen scavengers where barrier protection is most needed, creating local quality variations that solve both contradictions.
2Reliability
If a single layer preform with additives is used, then oxygen barrier performance is achieved, but scrap material contains additives that complicate reprocessing and increase costs
Solution Approach 1:
The preform is segmented into multiple injection phases creating additive-free and additive-containing layers. The additive-free first layer produces clean scrap that can be reprocessed at lower cost, while the additive-containing layers provide the necessary oxygen barrier, thus reducing overall waste reprocessing costs while maintaining protection.
Solution Approach 2:
The additive-free first layer is designed to be easily discarded as clean scrap that can be recovered and reprocessed without the complications of additive contamination. This selective discarding and recovering strategy reduces waste management costs while the additive-containing layers are retained for their barrier functionality.
3Reliability
If multiple layers with additives are created in the preform, then oxygen scavenger effectiveness is improved, but the complexity of the injection molding process increases
Solution Approach 1:
The injection molding process is segmented into distinct phases (first, second, third injections) that create layered structures with different additive compositions. While this increases process steps, each phase is relatively simple and can be controlled through standard injection molding parameters, making the complexity manageable and worthwhile for the enhanced oxygen scavenger effectiveness.
Solution Approach 2:
The preform uses composite material structures with different layers containing different additives (or lack thereof). This composite approach improves oxygen scavenger effectiveness by positioning additives strategically in layers 2 and 3, while the overall process remains a standard injection molding operation that, though multi-phased, is industrially manageable.
4Reliability
If the first layer of the preform contains additives, then oxygen barrier performance is uniform throughout, but the scrap material from trimming contains additives that cause reprocessing issues
Solution Approach 1:
The preform is segmented so that the first layer (which becomes trim scrap) is additive-free, while subsequent layers contain oxygen scavenger additives. This segmentation ensures that the scrap generated during trimming does not contain additives that would cause reprocessing contamination, while the remaining container walls still provide uniform oxygen barrier protection through layers 2 and 3.
Solution Approach 2:
Different regions of the preform have different material properties matched to their function: the first layer (trim region) is additive-free for clean scrap generation, while the second and third layers (container wall regions) contain oxygen scavengers for barrier protection. This local quality differentiation solves both the uniform barrier requirement and the scrap contamination problem.
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 enhances the efficiency of material reuse, reduces processing costs, and prevents layer delamination, thereby improving the economic viability and performance of plastic blow-molded containers.
Implementation Method 1
injection molding a preform using a two phase injection system having a first phase in which a material is injected into the preform and a second phase in which the material is injected into the preform
Implementation Method 2
The preform is blow molded into an intermediate article
Data Source
AI summary
A method includes injection molding a preform using a two phase injection system having a first phase in which a material is injected into the preform and a second phase in which the material is injected into the preform. The preform is disposed in a mold. The preform is blow molded into an intermediate article. The intermediate article is trimmed to form a finished container. The first phase includes injecting a material into the preform to form a single layer of the preform and the second phase includes injecting the material to form inner and outer layers and an intermediate layer between the inner and outer layers. The inner and outer layers include the material and the intermediate layer includes at least one additive. Finished containers are disclosed.