Polypropylene Luggage Case Composition Balancing Impact and Stress Whitening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing luggage cases made from propylene-based polymers face challenges in achieving a combination of good mechanical properties such as stress whitening resistance, gloss, and impact strength, particularly under severe conditions encountered during air travel.
Innovation Solution
A composition comprising a heterophasic propylene copolymer, propylene homopolymer, and a polyolefin-based elastomer with specific melt flow indices and ratios, optimized for luggage cases, is developed to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a propylene-based polymer is used for luggage cases, then the basic structural requirements are met, but the combination of mechanical properties such as stress whitening resistance, gloss, and impact strength is insufficient
Solution Approach 1:
The patent uses a composite material system consisting of heterophasic propylene copolymer (containing both crystalline and amorphous phases) combined with polyolefin elastomer and propylene homopolymer. This multi-phase composite structure provides both the rigidity needed for impact strength and the flexibility needed for stress whitening resistance, resolving the contradiction between these two mechanical properties
Solution Approach 2:
The patent optimizes specific parameters including the melt flow index of the polyolefin elastomer (15-50 dg/min) and the total amount of amorphous phase (20.0-26.0 wt%), along with the melt flow index of the overall composition (25-60 dg/min). These parameter adjustments balance the material's crystallinity and amorphous content to achieve both high impact strength and stress whitening resistance
2Strength
If the dispersed rubber phase amount is increased to improve impact strength, then impact resistance improves, but the total composition balance and processing properties may deteriorate
Solution Approach 1:
The patent precisely controls the amount of dispersed rubber phase (a2) in combination with polyolefin elastomer (C) to be 20.0-26.0 wt% of the total composition, and adjusts the melt flow index of the overall composition to 25-60 dg/min. These parameter optimizations ensure sufficient impact strength while maintaining good processing properties and manufacturing ease
Solution Approach 2:
The patent creates a heterogeneous structure where the dispersed ethylene-α-olefin copolymer (a2) and polyolefin elastomer (C) are distributed as discrete phases within the propylene-based matrix (a1). This local distribution of rubber phases provides impact strength enhancement while the continuous matrix maintains processing properties
Data Source
AI summary
The invention relates to a composition comprising (A) a heterophasic propylene copolymer, (B) a propylene homopolymer and (C) a polyolefin-based elastomer, wherein (A) the heterophasic propylene copolymer consists of (a1) a propylene-based matrix, wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene copolymer consisting of at least 90 wt% of propylene monomer units and at most 10 wt% of ethylene and/or a- olefin monomer units, based on the total weight of the propylene-based matrix and (a2) a dispersed ethylene-α-olefin copolymer, wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-α-olefin copolymer in the heterophasic propylene copolymer is 100 wt%, (C) the polyolefin-based elastomer has a melt flow index of 15 to 50 dg/min measured according to ASTM D1238 with a 2.16 kg load at 190 °C, the total amount of (a2) and (C) with respect to the total composition is 20.0 to 26.0 wt% and the composition has a melt flow index as measured according to ISO1133-1:2011 with a 2.16kg load at 230°C of 25 to 60 dg/min.