Spunbond Nonwoven Materials Using Starch-Based Polymers
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Solution Overview
Problem
Current methods fail to effectively incorporate high molecular weight starch-based polymeric materials into nonwoven articles and thin fibers due to their high viscosity and complex branched characteristics, which hinders their use in commercial spinning processes, and existing biodegradable alternatives do not significantly differ from petrochemical-based plastics in terms of physical properties.
Innovation Solution
A method for spinning high molecular weight starch-based polymeric materials by controlling temperature and shear rate, using a thermoplastic diluent polymer to achieve suitable rheological characteristics, allowing for the production of nonwoven web substrates and thin fibers through processes like spunbond, melt blown, and yarn production, while maintaining mechanical properties and enhancing biodegradability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight starch-based polymeric materials are used, then biodegradability and mechanical properties are improved, but viscosity increases making processing difficult
Solution Approach 1:
The patent applies parameter changes by controlling temperature and shear rate during processing. Specifically, the method processes starch-based polymeric materials at temperatures of 150°C to 250°C and shear rates of 100 to 1000 per second, which optimizes the rheological properties to enable spinning while preserving the high molecular weight structure necessary for biodegradability and mechanical strength.
2Strength
If high molecular weight starch-based polymeric materials are used, then mechanical properties are improved, but viscosity increases hindering fiber formation
Solution Approach 1:
The patent utilizes parameter changes by optimizing processing temperature (150°C to 250°C) and shear rate (100 to 1000 per second) to achieve suitable rheological characteristics that enable fiber formation from high molecular weight starch-based materials while maintaining their mechanical properties.
Solution Approach 2:
The patent employs composite materials by blending starch-based polymeric materials with thermoplastic polymers. This composite approach combines the biodegradability and mechanical properties of starch with the processability of thermoplastics, enabling successful fiber formation through commercial spinning processes.
3Reliability
If starch-based polymeric materials are incorporated into nonwoven materials, then biodegradability is enhanced, but rheological characteristics become poor
Solution Approach 1:
The patent applies parameter changes by controlling processing temperature (150°C to 250°C) and shear rate (100 to 1000 per second) to optimize the rheological behavior of starch-based polymeric materials during nonwoven formation, enabling proper flow and bonding characteristics while preserving biodegradability.
Solution Approach 2:
The patent uses composite materials by formulating blends of starch-based polymeric materials with thermoplastic polymers. This composite formulation adjusts the rheological characteristics to be suitable for nonwoven manufacturing processes while maintaining the biodegradable nature of the starch component.
4Productivity
If commercial spinning processes are used, then productivity is maintained, but high viscosity materials cannot be processed
Solution Approach 1:
The patent applies parameter changes by processing at commercial line speeds with shear rates of 100 to 1000 per second and temperatures of 150°C to 250°C. These parameter optimizations enable the processing of high viscosity, high molecular weight starch-based materials through commercial spinning equipment without reducing productivity.
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
Enables the production of nonwoven articles and thin fibers with enhanced mechanical properties and biodegradability, using high molecular weight starch-based materials, which can be processed at commercial line speeds and shear rates, overcoming the viscosity challenges of traditional starch-based materials.
Implementation Method 1
using a thermoplastic diluent polymer to achieve suitable rheological characteristics
Implementation Method 2
by controlling temperature and shear rate
Implementation Method 3
by controlling temperature and shear rate
Data Source
AI summary
Described are very high molecular weight (e.g., over 2 million, such as 3-20 million g/mol) starch-based materials, and formulations including such, which can be spun in spunbond, melt blown, yarn, or similar processes. Even with such very high molecular weights, the formulations can be processed at commercial line speeds, with spinneret shear viscosities of 1000 sec−1, without onset of melt flow instability. The starch-based material can be blended with one or more thermoplastic materials having higher melt flow index value(s), which serve as a diluent and plasticizer, allowing the very viscous starch-based component to be spun under such conditions. The particular melt flow index characteristics of the thermoplastic diluent material can be selected based on what type of process is being used (e.g., spunbond, melt blown, yarn, etc.). The starch-based material may exhibit high shear sensitivity, strain hardening behavior, and/or very high critical shear stress (e.g., at least 125 kPa).