Liquid-Expanded Polyester Preforms for Sterile Blow Molding
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Solution Overview
Problem
Current plastic bottle manufacturing processes, such as blow molding, require high energy and pressure to achieve proper crystallization and sterilization, often resulting in the formation of toxic byproducts like acetaldehydes and ethanol, and separate steps for sterilization and filling, which increase costs and complexity.
Innovation Solution
The use of liquids, particularly water, under pressure to expand and shape preforms instead of air, allowing for improved molecular orientation, reduced energy consumption, and integrated sterilization and filling processes, minimizing the formation of toxic byproducts and eliminating the need for additional sterilization steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If air is used to expand the preform in blow molding, then the preform can be stretched into the bottle shape, but high energy and pressure are required and toxic byproducts like acetaldehydes are formed
Solution Approach 1:
The patent replaces pneumatic expansion (using air) with hydraulic expansion (using liquid). The liquid under pressure is introduced into the preform to expand it into the bottle shape, eliminating the formation of toxic byproducts like acetaldehydes that occur during air-based blow molding while still achieving proper form formation.
2Strength
If high pressure is applied during blow molding to achieve proper crystallization, then the bottle structure is strengthened, but energy consumption increases and production costs rise
Solution Approach 1:
The patent changes the physical state parameter of the expansion medium from gas (air) to liquid. This parameter change allows for more efficient pressure transmission and better control of the expansion process, achieving proper crystallization and mechanical strength with reduced energy input compared to traditional air-based blow molding.
3Reliability
If separate sterilization and filling steps are used, then product safety is ensured, but process complexity and production costs increase
Solution Approach 1:
The patent combines the expansion and sterilization functions into a single integrated process step. The liquid used to expand the preform simultaneously serves as a sterilizing agent, eliminating the need for separate sterilization and filling steps while ensuring product safety and reducing process complexity.
4Productivity
If traditional blow molding processes are used, then bottles can be produced, but additional sterilization steps are required increasing time and cost
Solution Approach 1:
The liquid expansion medium performs dual functions: it expands the preform into the bottle shape and simultaneously sterilizes the container. This self-service approach eliminates the need for separate sterilization steps, reducing production time and increasing overall productivity.
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 results in lighter, more cost-effective bottles with improved mechanical strength and reduced contamination risks, enabling immediate filling with sterile products while reducing energy consumption and production costs.
Implementation Method 1
introducing liquid under pressure into said preform located within said mold for stretching said preform to assume the shape of the surrounding mold cavity
Implementation Method 2
heating said mold to approximately the melting point of the thermoplastic material
Data Source
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AI summary
This specification discloses an improved polyester resin for use in such a process comprising a crystallizable polyester polymer wherein the polyester polymer is comprised of acid moieties and glycol moieties, with at least 85% of the total moles of acid moieties being terephthalate derived from terephthalic acid or its dimethyl ester and at least 85% of the total moles of glycol moieties derived from ethylene glycol and with at least 2% of the total moles of acid plus glycol moieties derived from a primary comonomer with the mole percents of the acid plus glycol moieties totaling 100 mole % to improve the process of forming a polyester resin container from a preform (12) utilizing a step of expansion carried out with a cavity or a mould (16), wherein, during said expansion step, an incompressible fluid is injected through the opening of said preform (12) to form said container.