Propylene Copolymer Composition for Extrusion Blow Molding
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Solution Overview
Problem
Extrusion blow molding (EBM) processes face challenges in achieving uniform optical properties and mechanical strength in molded articles, such as bottles, due to complexities in the solidification step and limited control over the inner surface structure.
Innovation Solution
A propylene copolymer composition is developed, comprising two propylene copolymer fractions with specific comonomer content and melt flow rates, combined with an α-nucleating agent. This composition is designed to improve the optical and mechanical properties of EBM products by enhancing impact strength, stiffness, and reducing haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If extrusion blow molding process is used to produce bottles, then flexibility and cost-effectiveness in producing different sizes and shapes are improved, but optical properties (surface uniformity, gloss, transparency) deteriorate due to complex solidification step and limited mold contact
Solution Approach 1:
The patent applies parameter changes by modifying the polymer composition parameters - using a propylene copolymer with specific comonomer content (4.0-8.0 wt.%) and controlled melt flow rate (1-5 g/10 min). This changes the material's crystallization behavior and solidification characteristics, enabling better optical properties while maintaining EBM process flexibility.
Solution Approach 2:
The patent uses a composite material approach by combining propylene copolymer with an alpha-nucleating agent. This composite composition enhances the polymer's crystallization kinetics and solidification uniformity, improving surface quality and optical properties in EBM articles without sacrificing process versatility.
2Ease of manufacture
If extrusion blow molding process is used, then production cost and flexibility are improved, but mechanical properties (impact strength, stiffness) deteriorate due to inferior surface structure control
Solution Approach 1:
The patent changes material parameters by selecting propylene copolymer with specific comonomer content (4.0-8.0 wt.%) and melt flow rate (1-5 g/10 min), which optimizes the balance between processability and mechanical property development during EBM solidification.
Solution Approach 2:
The patent employs a composite material system combining propylene copolymer with alpha-nucleating agent, which enhances crystallization uniformity and mechanical property development, achieving high impact strength and stiffness while maintaining EBM cost-effectiveness.
3Device complexity
If conventional propylene polymer composition is used in EBM, then processing is simplified, but optical properties (haze) and mechanical properties (impact strength) deteriorate
Solution Approach 1:
The patent applies parameter changes by defining specific ranges for comonomer content (4.0-8.0 wt.%) and melt flow rate (1-5 g/10 min) of the propylene copolymer, optimizing crystallization behavior to achieve low haze and high impact strength without complicating the EBM processing.
Solution Approach 2:
The patent uses a composite material approach by incorporating an alpha-nucleating agent into the propylene copolymer composition, which enhances crystallization kinetics and uniformity, simultaneously improving optical clarity (low haze) and mechanical strength (high impact) while maintaining simple EBM processing.
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 propylene copolymer composition significantly improves the optical and mechanical properties of extrusion blow molded articles, achieving low haze, high flexural modulus, and high impact strength, while maintaining high safety for food contact applications.
Implementation Method 1
the complexity of the solidification step compared to normal injection molding
Implementation Method 2
an α-nucleating agent (NU)
Data Source
AI summary
The present invention is directed to a propylene polymer composition comprising at least one propylene copolymer (C-PP), and an α-nucleating agent (NU), wherein the propylene copolymer (C-PP) comprises two propylene copolymer fractions (PP1) and (PP2), wherein propylene copolymer fraction (PP1) is contained in the propylene copolymer (C-PP) in an amount of 30 to 70 wt. % and the propylene copolymer fraction (PP2) is contained in the propylene copolymer (C-PP) in an amount of 70 to 30 wt. %, the comonomer content of propylene copolymer fraction (PP1) is in the range of 0.5 to 2.5 wt.-% and the comonomer content of the propylene copolymer fraction (PP1) is lower compared to the comonomer content of the propylene copolymer fraction (PP2), and the propylene polymer composition has (a) a melt flow rate MFR2 (230° C.) measured according to according to ISO 1133 of 1 to 5 g/10 min., and (b) a comonomer content of 4.0 to 8.0 wt. %, the comonomer(s) being ethylene and/or at least one C4 to C12 α-olefin. The above propylene polymer composition has improved impact and optical properties. The invention further provides a method of producing the above propylene polymer composition and an extrusion blow molded article comprising the above propylene polymer composition.