Metallocene Multimodal Polyethylene Composition for Stable Film Processing
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Solution Overview
Problem
Unimodal polyethylene polymers face challenges in melt processing, leading to quality issues and poor bubble stability in film production, while multimodal polymers suffer from inhomogeneity and high gel content, necessitating a balance between higher throughput and processability without compromising mechanical and optical properties.
Innovation Solution
A metallocene-catalysed multimodal polyethylene copolymer with specific ethylene polymer components and fractions, designed to have distinct MFR, density, and rheological properties, enhancing shear thinning and processability, thereby improving bubble stability and film properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If unimodal polyethylene polymers are used for film applications, then good optical properties like low haze are achieved, but melt processing is not satisfactory and causes quality problems
Solution Approach 1:
The patent segments the polymer into unimodal and multimodal components with distinct molecular weight distributions. The unimodal fraction provides good optical properties while the multimodal fraction improves melt processing, resolving the contradiction between optical quality and manufacturability.
Solution Approach 2:
The patent changes the molecular weight distribution parameters by combining unimodal and multimodal fractions with specific MFR values. This parameter optimization allows simultaneous achievement of low haze (optical property) and satisfactory melt processing behavior.
2Ease of manufacture
If multimodal PE polymers are used to improve processability, then melt processing is better, but melt homogenisation is problematic resulting in inhomogeneous final product with high gel content
Solution Approach 1:
The patent segments the multimodal polymer into controlled fractions with specific MFR ranges. By carefully defining the unimodal (30-70 wt%) and multimodal (70-30 wt%) components with specific MFR values, the patent achieves both improved processability and reduced gel content for homogeneous final product.
Solution Approach 2:
The patent optimizes the molecular weight distribution parameters by specifying MFR values for different fractions. The unimodal fraction has MFR 0.1-10 g/10min and multimodal fraction has MFR 10-100 g/10min, creating a balanced composition that improves melt processing while maintaining product homogeneity and reducing gel content.
3Productivity
If MFR2 of polymer resin is increased to increase output in film production, then throughput increases, but bubble stability deteriorates
Solution Approach 1:
The patent segments the polymer into unimodal and multimodal fractions with complementary MFR values. The unimodal fraction (MFR 0.1-10 g/10min) provides bubble stability while the multimodal fraction (MFR 10-100 g/10min) enables higher throughput, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent changes the overall MFR2 parameter to a balanced range of 0.5-5.0 g/10min by combining fractions with different MFR values. This optimized parameter allows increased output while maintaining bubble stability during film blowing processes.
4Reliability
If MFR2 is decreased to improve bubble stability, then processability improves, but throughput and output are limited
Solution Approach 1:
The patent segments the polymer composition to include both low MFR unimodal fraction (for bubble stability) and high MFR multimodal fraction (for throughput). This segmentation allows the final product to achieve both reliable bubble stability and high production output simultaneously.
Solution Approach 2:
The patent optimizes the MFR2 parameter to a balanced range (0.5-5.0 g/10min) by combining fractions with different MFR characteristics. This parameter optimization enables the polymer to exhibit both good bubble stability and high throughput capability during film production.
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 copolymer achieves higher throughput and stable film production with reduced melt pressure and temperature, maintaining mechanical strength, impact resistance, and lower sealing initiation temperature.
Implementation Method 1
a metallocene-catalysed multimodal polyethylene copolymer (P) of ethylene with at least two different comonomers selected from alpha-olefins having from 4 to 10 carbon atoms
Implementation Method 2
Such a metallocene-catalysed multimodal polyethylene copolymer (P) has an improved rheological behavior, especially in terms of shear thinning index
Data Source
AI summary
The present disclosure relates to a metallocene-catalysed multimodal polyethylene copolymer, to the use of the multimodal copolymer of ethylene in film applications and to a film including a polymer composition of the disclosure.