PHA Preform Uniform Wall Thickness for Blow Molding
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Solution Overview
Problem
Biodegradable preforms made from poly(hydroxyalkanoate) (PHA) materials face challenges in moldability due to their low glass transition temperature, leading to irregular material distribution and thickness discrepancies during the blow molding process, which can result in blow-outs and inconsistent container quality.
Innovation Solution
The development of PHA preforms with a uniform wall thickness and specific compositions, including 40-99% poly(hydroxyalkanoate) copolymer, 0.1-10% nucleating agents, 0.005-3% melt strength enhancers, and optional additives, designed for reheat injection stretch blow molding to maintain consistent temperature and reduce deformation during reheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PHA preforms are heated to the melting temperature to make them pliable, then the preforms become moldable, but the PHA material flows and deforms from the original design, causing shrinkage to nearly half its size
Solution Approach 1:
The patent modifies the physical and chemical parameters of the PHA material by incorporating copolymers with different glass transition temperatures and adding nucleating agents. This allows the material to be processed at lower temperatures while maintaining moldability, thereby reducing deformation and shrinkage during the molding process.
Solution Approach 2:
The patent creates a composite PHA material system that includes copolymers (such as P3HB-co-P3HHx), nucleating agents, and other additives. This composite approach enables the material to achieve both pliability for molding and dimensional stability, preventing the excessive flow and deformation that occurs with pure PHA.
2Ease of operation
If PHA preforms are reheated for blow molding, then the material becomes pliable for shaping, but there is no self-regulation and material flows irregularly, causing thickness discrepancies
Solution Approach 1:
The patent changes the thermal and rheological parameters of the PHA material through copolymer composition and additive selection. This enables the material to exhibit self-regulating flow characteristics during reheating, ensuring uniform material distribution and consistent wall thickness in the final container.
Solution Approach 2:
The nucleating agents and copolymer composition create a self-regulating system where the material's crystallization and flow behavior automatically adjust during processing. This feedback mechanism ensures that material distributes evenly throughout the mold cavity, preventing thickness variations without requiring complex external control systems.
3Ease of manufacture
If PHA preforms have different thicknesses along the length, then material distribution may be adjusted, but thicker areas require more heat to become pliable, causing temperature differentials and increasing blow-out risk
Solution Approach 1:
The patent modifies the thermal properties of the PHA material by incorporating copolymers with lower glass transition temperatures and adding nucleating agents. This enables the material to become pliable at lower, more uniform temperatures, eliminating the temperature differentials that cause blow-outs in non-uniform preforms.
Solution Approach 2:
The patent incorporates nucleating agents and copolymer modifiers into the PHA material before molding. This preliminary modification ensures that the material has uniform heating characteristics and predictable flow behavior, preventing blow-outs before they can occur during the blow molding process.
4Object-generated harmful factors
If other biopolymers are used as alternatives to PET, then biodegradability is improved, but they are hard to mold or have dismal barrier properties
Solution Approach 1:
The patent creates a composite biopolymer system that combines PHA copolymers with nucleating agents, plasticizers, and other additives. This composite approach maintains the biodegradability advantage while achieving the moldability and barrier properties necessary for practical container applications.
Solution Approach 2:
The patent adjusts the chemical composition and molecular structure parameters of the biopolymer through copolymerization and additive incorporation. This enables the material to achieve both biodegradability and the processing characteristics needed for successful molding, overcoming the limitations of earlier biopolymer attempts.
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 uniform wall thickness and composition of the PHA preforms ensure consistent material flow and reduced blow-outs, resulting in more reliable and repeatable container production with improved biodegradability and compostability.
Implementation Method 1
from about 0.1 to about 10 weight percent of at least one nucleating agent
Implementation Method 2
from about 0.005 to about 3 weight percent of at least one melt strength enhancer
Implementation Method 3
the preform has a body having a uniform wall thickness throughout the body of the preform
Data Source
AI summary
A preform for a biodegradable container wherein the preform includes from about 40 to about 99 weight percent of a polymer derived from random monomeric repeating units having a structure ofwherein R1 is selected from the group consisting of CH3 and a C3 to C19 alkyl group, wherein the polymer comprises from about 20 to about 99 wt. % of the preform and wherein the monomeric units wherein R1=CH3 comprise 75 to 99 mol percent of the polymer and wherein the preform has a body having a uniform wall thickness throughout the body of the preform. A resin adapted for forming the preform is also disclosed.