Propylene Polymer Composition for Film Sealing and Processability
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Solution Overview
Problem
Current polymer compositions for films, particularly those made from propylene and its copolymers, face challenges in achieving optimal balance of properties such as melt flow rate, xylene solubility, and melting point for diverse applications like packaging and non-packaging items, where specific properties like sealing performance and flexibility are critical.
Innovation Solution
A polymer composition comprising specific weight percentages of propylene-based copolymers with 1-hexene and ethylene, along with a copolymer of 1-butene and ethylene, tailored to achieve a range of melt flow rates, xylene solubility, and melting points, optimized for film production, including biaxially oriented polypropylene films, with a sealing layer configuration for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copolymers of propylene and 1-hexene with single molecular weight distribution are used, then the polymer composition has good processability, but the film sealing performance and flexibility are insufficient
Solution Approach 1:
The patent divides the polymer composition into multiple copolymer components (a, b, and c) with different molecular weight distributions and comonomer contents. Component (a) has lower molecular weight for processability, component (b) has higher molecular weight for mechanical strength, and component (c) is propylene-ethylene copolymer for sealing performance. This segmentation allows each component to contribute its specific advantage to the overall film performance.
Solution Approach 2:
The patent creates a composite polymer system by combining three different copolymer types in specific weight ratios (30-70 wt% component a, 10-40 wt% component b, 10-40 wt% component c). This composite approach enables the film to simultaneously achieve good processability, mechanical strength, and sealing performance that cannot be obtained with a single copolymer type.
2Ease of operation
If higher content of 1-hexene derived units is incorporated, then the film flexibility improves, but the melting point decreases
Solution Approach 1:
The patent applies local quality by distributing 1-hexene derived units selectively in specific copolymer components rather than uniformly throughout the entire polymer composition. Component (a) contains 6.0-12.0 wt% 1-hexene for flexibility, while component (b) contains 18.0-30.0 wt% 1-hexene for enhanced flexibility. This localized incorporation allows flexibility improvement while maintaining overall melting point through the presence of higher melting point components.
Solution Approach 2:
The patent changes the composition parameters by controlling the total 1-hexene content (3.0-8.0 wt%) and distributing it across different copolymer components with different molecular weights. This parameter optimization allows the film to achieve desired flexibility while maintaining adequate melting point for processing.
3Reliability
If copolymer composition is optimized for sealing performance, then the sealing properties improve, but the processing characteristics deteriorate
Solution Approach 1:
The patent creates a dynamic balance in the polymer composition by incorporating components with different molecular weight distributions. Component (a) with lower molecular weight provides good melt flow for processing, while component (b) with higher molecular weight and component (c) propylene-ethylene copolymer provide sealing performance. The specific weight ratios (30-70 wt% component a, 10-40 wt% component b, 10-40 wt% component c) optimize this dynamic balance between processability and sealing properties.
Data Source
AI summary
A polymer composition made from or containing:A) from 70 wt % to 95 wt % of a propylene-based polymer composition made from or containing:a) from 15 wt % to 35 wt % of a copolymer of propylene and 1-hexene containing from 6.2 to 8.5% by weight, of 1-hexene derived units;b) from 15 wt % to 35 wt % of a copolymer of propylene and 1-hexene containing from 10.4 wt % to 14.5 wt %, of 1-hexene derived units; andc) from 38 wt % to 68 wt % of a propylene ethylene copolymer,wherein the sum of the amount of a), b), and c) being 100; andB) from 5.0 wt % to 30.0 wt % of a copolymer of 1-butene and ethylene containing from 3.0 wt % to 4.2 wt % of ethylene derived units;wherein the sum of the amounts of A) and B) being 100 wt %.