Propylene Terpolymer Containers Impact Resistance
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Solution Overview
Problem
Existing containers, including those for food, lack optimal mechanical and optical properties such as impact resistance, low extractable hexane levels, and haze values, which are crucial for safety and quality.
Innovation Solution
A propylene-ethylene-1-hexene terpolymer with specific composition and processing methods, including visbreaking and use of Ziegler-Natta catalysts, to achieve desired mechanical and optical properties like high impact resistance and low hexane extractables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional propylene/ethylene/1-hexene terpolymer compositions are used for container production, then the polymer can be processed into containers, but the containers exhibit insufficient impact resistance and poor mechanical properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene content (0.2-1.0 wt%) and 1-hexene content (3.5-5.5 wt%) within specific ranges, and adjusting the melt flow rate (MFR) to 15-80 g/10 min. These parameter optimizations resolve the contradiction by achieving both improved impact resistance and adequate processability for container manufacturing.
2Strength
If higher comonomer content is used to improve mechanical properties, then impact resistance improves, but hexane extractables increase making the container unsuitable for food containment
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the comonomer content within narrow ranges: ethylene at 0.2-1.0 wt% and 1-hexene at 3.5-5.5 wt%. This parameter optimization achieves sufficient impact resistance while maintaining hexane extractables at acceptable levels for food contact applications.
Solution Approach 2:
The patent uses a terpolymer composite structure combining propylene, ethylene, and 1-hexene in specific proportions. This composite material approach allows the synergistic effect of different comonomers to improve mechanical properties while controlling extractable content, resolving the contradiction between strength and safety.
3Object-affected harmful factors
If the polymer composition is optimized for low hexane extractables, then food safety is improved, but the haze value increases reducing optical clarity
Solution Approach 1:
The patent resolves this contradiction by optimizing multiple parameters simultaneously: ethylene content (0.2-1.0 wt%), 1-hexene content (3.5-5.5 wt%), and MFR (15-80 g/10 min). This multi-parameter optimization achieves low hexane extractables for food safety while maintaining acceptable optical clarity with haze values controlled within specified ranges.
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 terpolymer containers exhibit improved impact properties, low haze values, and reduced hexane extractables, making them suitable for food containment with enhanced mechanical strength and optical clarity.
Implementation Method 1
polymerization in one or more polymerization steps in the presence of Ziegler-Natta catalysts
Implementation Method 2
In order to visbreak the polymer, known visbreaking agents can be used such as peroxides. With visbreaking it is possible to fine tune the MFR of the product.
Data Source
AI summary
A container comprising a propylene, ethylene, 1-hexene terpolymer wherein:(i) the content of ethylene derived units ranges from 0.2 wt % to 1.0 wt %;(ii) the content of 1-hexene derived units ranges from 3.5 wt % to 5.5 wt %;(iii) the content of ethylene derived units fulfills the following equation (I);C2<C6*0.16 (I);wherein C2 is the content of ethylene derived units wt % and C6 is the content of 1-hexene derived units wt %; and(iv) the melt flow rate MFR measured according to ISO 1133, 230° C., 2.16 kg ranges from 15 to 80 g/10 min.