Visbroken Propylene Terpolymer for Low Seal Initiation Temperature Packaging
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Solution Overview
Problem
Current polypropylene films for packaging struggle to achieve a balance of low sealing initiation temperature (SIT), high hot-tack, and improved optical properties, particularly in sterilization conditions, with monolayer films facing challenges in compatibility and property optimization.
Innovation Solution
A polypropylene composition comprising at least 50% of a visbroken propylene terpolymer with specific ethylene and α-olefin comonomer content, processed with a Ziegler-Natta catalyst, which is then visbroken to enhance melt flow rate and thermal stability, combined with optional additives for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If polypropylene films are designed to achieve low sealing initiation temperature, then sealing speed is improved, but hot-tack strength deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the comonomer composition (ethylene content 0.5-3.0 wt%, C4-C10 α-olefin content 5.5-15.0 wt%) and molecular weight distribution (Mw/Mn ratio 2.0-10.0) of the propylene terpolymer. This optimization allows the film to achieve low SIT (90-110°C) for fast sealing while maintaining adequate hot-tack strength through the balanced compositional parameters.
2Reliability
If multiple components are used in monolayer film to improve properties, then sealing and mechanical properties are improved, but optical properties (haze) deteriorate
Solution Approach 1:
The patent employs composite materials by creating a propylene terpolymer with three different comonomer units (ethylene, C4 α-olefin, and C5-C10 α-olefin) incorporated into a single polymer chain. This ternary copolymer structure provides diverse properties (sealing, mechanical strength, and optical clarity) within one homogeneous material, avoiding the inhomogeneity and high haze associated with multi-component blends.
Solution Approach 2:
The patent applies homogeneity by ensuring the terpolymer components are compatibly integrated at the molecular level through coordinated polymerization. The resulting film shows homogeneous structure without phase separation, achieving low haze values despite the complex three-comonomer composition, thereby maintaining excellent optical properties.
3Reliability
If polypropylene composition is optimized for low SIT and high hot-tack, then sealing performance is improved, but thermal stability for sterilization deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the comonomer content ranges (ethylene 0.5-3.0 wt%, C4-C10 α-olefin 5.5-15.0 wt%) and molecular weight distribution (Mw/Mn 2.0-10.0) to achieve a balance where the film maintains low SIT (90-110°C) and high hot-tack while preserving sufficient thermal stability for sterilization processes.
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 composition achieves optimized sealing behavior with low SIT, high hot-tack, and beneficial optical properties, including low haze, while maintaining thermal stability for sterilization, thus enhancing the performance of packaging films.
Implementation Method 1
processed with a Ziegler-Natta catalyst
Implementation Method 2
visbroken to enhance melt flow rate
Data Source
AI summary
New polypropylene composition, which combines low sealing initiation temperature (SIT), high hot-tack and good optical properties, like low haze, the use of such polypropylene composition and articles made therefrom.