Propylene Elastomer Spunbond Fabric Processability
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Solution Overview
Problem
Existing spunbond processes face challenges in achieving both superior processability and elasticity in nonwoven materials, often requiring trade-offs that impair either property, and attempts with propylene-ethylene copolymers result in processing difficulties and compromised elastic properties.
Innovation Solution
A polymer composition comprising a propylene-ethylene copolymer with a melt flow rate (MFR) of 30-80 g/10 min and ethylene content of 10-14.5 wt%, optionally with a small amount of propylene-based thermoplastic and additives, is used to form spunbond materials with enhanced elasticity and processability, allowing for bonding and further processing without excessive tackiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chain scission of polymer chains is used to increase MFR for better processability, then processability is improved, but elasticity of the resulting article is impaired
Solution Approach 1:
The invention changes the chemical composition parameters of the polymer by incorporating specific amounts of ethylene (5-20 wt%) and vinyl acetate (5-20 wt%) comonomers into the polypropylene matrix. This compositional parameter change allows achieving both high MFR (30-80 g/10min) for processability and maintained elasticity, resolving the contradiction between processability and elastic properties
Solution Approach 2:
The invention creates a composite polymer system where polypropylene serves as the base matrix and is combined with ethylene and vinyl acetate comonomers. This composite structure enables the material to exhibit both improved processability through controlled MFR and retained elastic properties, overcoming the trade-off between these two characteristics
2Strength
If higher extrusion temperatures are used to achieve suitable MFR for maintaining elastic properties, then elasticity is maintained, but crystallization rate decreases causing excessive tackiness
Solution Approach 1:
The invention modifies the polymer composition parameters by adding ethylene and vinyl acetate comonomers, which change the crystallization behavior of the polymer. This compositional change enables the material to crystallize at lower temperatures at adequate rates, resolving the contradiction between maintaining elasticity and achieving sufficient crystallization rate without excessive tackiness
3Strength
If propylene-ethylene copolymer compositions are used to improve elasticity, then elastic properties are enhanced, but processing becomes difficult
Solution Approach 1:
The invention creates a ternary composite system combining polypropylene, ethylene, and vinyl acetate. This composite approach allows achieving enhanced elasticity from the ethylene component while the vinyl acetate component and overall composition design maintain good processability, overcoming the processing difficulties associated with binary propylene-ethylene copolymers
Solution Approach 2:
The invention optimizes the compositional parameters within specific ranges: polypropylene (60-70 wt%), ethylene (5-20 wt%), and vinyl acetate (5-20 wt%). These controlled parameter changes enable balancing elastic properties with processability, resolving the contradiction between enhanced elasticity and difficult 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 resulting spunbond materials exhibit improved elasticity, including greater than 250% elongation at break, low permanent set, and reduced hysteresis, while maintaining suitable processability, enabling the production of high-quality nonwoven fabrics for various applications.
Implementation Method 1
the polymer composition is melted
Implementation Method 2
Cool or quench air is passed over the filaments as they exit, with the aim of cooling the filaments so as to solidify them
Implementation Method 3
the polymer composition will not crystallize as readily or as quickly upon being extruded
Data Source
AI summary
A polymer composition for forming spunbond fabrics offers a unique combination of simplicity and processability, while allowing fabrics formed therefrom to exhibit suitable elasticity and/or tensile strength. The polymer composition includes an propylene-based elastomer component exhibiting a particular combination of MFR and comonomer content, so as to allow for improved processability with minimal, if any, need for blending partners in the polymer composition, while still permitting fabrics formed therefrom to exhibit improved elasticity and/or tensile strength.