Propylene Impact Copolymers for Cold Drop Resistance
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Solution Overview
Problem
Propylene-based random copolymers and homopolymers used in injection stretch blow molding (ISBM) exhibit poor drop impact strength, particularly at cold temperatures, making them unsuitable for containing refrigerated food and beverages.
Innovation Solution
The use of propylene-based impact copolymers with a melt flow rate of 1 dg/min to 150 dg/min, which are injection molded into preforms and then stretch-blowed into articles, providing improved cold temperature drop impact resistance and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If propylene-based random copolymers or homopolymers are used for injection stretch blow molding, then the manufacturing process is simple and cost-effective, but the drop impact strength is poor especially at cold temperatures
Solution Approach 1:
The patent uses propylene-based impact copolymers that are composite materials containing polypropylene and rubber phases. These copolymers combine the manufacturing advantages of propylene-based materials with improved impact strength through the rubber phase incorporation, resolving the contradiction between ease of manufacture and drop impact strength.
Solution Approach 2:
The patent modifies the polymer composition parameters by controlling the rubber phase content (5-20 wt%) and comonomer composition to achieve both ease of processing and improved cold temperature impact strength. This parameter optimization resolves the technical contradiction.
2Quantity of substance
If propylene-based random copolymers are used for ISBM articles, then the production cost is lower, but the cold temperature drop impact resistance is insufficient for refrigerated applications
Solution Approach 1:
The invention employs propylene-based impact copolymers with rubber phases that provide enhanced cold temperature impact resistance while maintaining cost-effectiveness. The composite structure allows the material to perform reliably in refrigerated applications without significantly increasing production cost.
Solution Approach 2:
By optimizing the rubber phase content and comonomer composition parameters, the patent achieves improved cold temperature drop impact resistance (at least 6 feet) while maintaining economical production costs, thus resolving the contradiction between quantity of substance and reliability.
3Strength
If propylene-based impact copolymers with specific melt flow rate are used, then the cold temperature drop impact strength is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent specifies a melt flow rate range (1-150 dg/min) for the propylene-based impact copolymer that balances improved cold temperature drop impact strength with manageable manufacturing process complexity. This parameter specification resolves the contradiction by providing a practical range rather than requiring precise control.
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 propylene-based impact copolymers result in ISBM articles with a maximum top load of at least 160 N and cold temperature drop impact resistance of at least 6 feet, significantly surpassing the performance of articles made from random copolymers, ensuring enhanced durability for refrigerated containers.
Implementation Method 1
a propylene-based impact copolymer exhibiting a melt flow rate of from about 1 dg/min to about 150 dg/min
Implementation Method 2
injection molding the propylene-based impact copolymer into a preform and stretch-blowing the preform into an article
Data Source
AI summary
Injection stretch blow molded (ISBM) articles and methods of forming the same are described herein. The ISBM articles generally include a propylene-based impact copolymer.