Propylene-Ethylene Copolymer Suppressing Component Bleeding
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Solution Overview
Problem
Propylene polymers used in molded articles, such as films and automobile parts, face issues with component bleeding at high temperatures, leading to reduced stickiness resistance, heat resistance, and appearance changes, which are not adequately addressed by existing technologies.
Innovation Solution
A propylene-ethylene-α-olefin copolymer with specific molecular composition and properties, including a high isotactic triad fraction, controlled melt flow rate, and melting point, is developed to enhance flexibility, heat resistance, and reduce component elution, maintaining stickiness resistance and appearance at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional propylene polymers are used to provide flexibility and processability, then the material exhibits good flexibility and ease of manufacture, but component bleeding occurs at high temperatures leading to poor stickiness resistance and heat resistance
Solution Approach 1:
The invention changes the compositional parameters by introducing a specific copolymer structure with controlled ethylene content (5-30 mol%) and α-olefin content (70-95 mol%), along with specific molecular weight distribution (Mw/Mn ≤ 3.0) and melting point (≤ 100°C), to suppress component bleeding while maintaining flexibility
Solution Approach 2:
The invention creates a composite polymer system by combining propylene, ethylene, and α-olefin in specific ratios to form a copolymer that integrates the advantages of each component: propylene provides flexibility, ethylene improves heat resistance, and α-olefin controls crystallinity and melting behavior
2Ease of manufacture
If propylene polymers with low molecular weight are used to improve processability and flexibility, then ease of manufacture and flexibility are enhanced, but stickiness resistance at high temperatures deteriorates
Solution Approach 1:
The invention optimizes the molecular weight parameters by controlling the weight average molecular weight (Mw) to be 10,000-1,000,000 and the molecular weight distribution (Mw/Mn) to be 3.0 or less, achieving a balance between processability and high-temperature performance
Solution Approach 2:
The invention creates a dynamic molecular weight distribution that allows the polymer to flow easily during processing (good processability) while maintaining structural integrity at high temperatures (good stickiness resistance) through controlled chain length distribution
3Object-affected harmful factors
If propylene polymers are used to provide environmental aptitude and hygiene, then ecological compatibility and safety are improved, but appearance retention and thickness maintainability at high temperatures worsen
Solution Approach 1:
The invention changes the thermal parameters by controlling the melting point to be 100°C or lower, which prevents excessive softening and deformation at high temperatures, thereby maintaining appearance and thickness while preserving environmental benefits
Data Source
AI summary
A propylene-ethylene-α-olefin copolymer satisfying: (I) a content of a propylene-derived constituent unit (i) is 50 to 92 mol %, a content of an ethylene-derived constituent unit (ii) is 5 to 20 mol %, and a content of a C4-20 α-olefin-derived constituent unit (iii) is 3 to 30 mol %, provided that (i) to (iii) total 100 mol %; (II) an mm fraction calculated by 13C-NMR is 85% or more; (III) 0.9≤MOE/(2MO×ME)≤1.5 wherein MOE represents a mole fraction of chains of propylene and ethylene and chains of the C4-20 α-olefin and ethylene in total to the total dyad, MO represents mole fractions of propylene and the C4-20 α-olefin in total, and ME represents a mole fraction of ethylene; (IV) an MFR is 1 to 3 g/10 minutes; and (V) a melting point measured by DSC is less than 100° C., or no melting peak is observed.