Melt-Blown Nonwoven Production with Shear-Based Molecular Weight Control
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Solution Overview
Problem
Existing methods for producing low molecular weight polymers, such as using peroxides or twin-screw kneading extruders, result in spatial non-uniformity of molecular weight distribution and thermal deterioration, leading to issues like fiber breakage during non-woven fabric production.
Innovation Solution
A production device that applies shear force to high molecular weight polymers using a continuous high shearing device, without additives, to efficiently reduce molecular weight and suppress thermal deterioration, enabling the production of low molecular weight polymers suitable for non-woven fabrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If peroxide is used to reduce molecular weight, then molecular weight reduction is achieved, but spatial non-uniformity occurs in molecular weight distribution and dispersion increases
Solution Approach 1:
The patent replaces the chemical method (peroxide-induced degradation) with a mechanical method (twin-screw kneading extrusion) to reduce molecular weight. The mechanical shear force and friction heat generated during kneading extrusion break down the polymer chains uniformly throughout the material, eliminating the spatial non-uniformity problem associated with peroxide addition. This mechanical substitution achieves both molecular weight reduction and uniform distribution.
Solution Approach 2:
The patent introduces a twin-screw kneading extruder as an intermediary device between the polymer feed and the final product. This intermediary applies controlled mechanical energy and heat to gradually reduce molecular weight through kneading and extrusion, ensuring uniform degradation throughout the material rather than localized degradation from peroxide addition.
2Productivity
If twin-screw kneading extruder is used for molecular weight reduction, then molecular weight is reduced continuously, but polymer undergoes large degree of thermal deterioration
Solution Approach 1:
The patent employs continuous kneading extrusion in a twin-screw extruder to maintain steady-state molecular weight reduction. The continuous action ensures consistent shear force application and uniform heat distribution throughout the processing, preventing localized overheating and thermal deterioration while maintaining high productivity.
Solution Approach 2:
The patent optimizes processing parameters including temperature, screw rotation speed, and feed rate to balance molecular weight reduction with thermal protection. By carefully controlling these parameters, the process achieves efficient molecular weight reduction through mechanical shear while minimizing thermal degradation of the polymer.
3Quantity of substance
If polymerization conditions are adjusted to produce low molecular weight polymer, then desired molecular weight is achieved, but production cost increases
Solution Approach 1:
The patent performs molecular weight reduction as a preliminary processing step after polymerization, rather than controlling molecular weight during polymerization. This allows the use of standard, cost-effective polymerization processes to produce high molecular weight polymer, which is then mechanically degraded to the desired lower molecular weight, avoiding the need for expensive specialized polymerization conditions or catalysts.
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 method allows for efficient, cost-effective production of low molecular weight polymers with reduced polydispersity, suitable for non-woven fabrics, by minimizing thermal deterioration and avoiding issues like fiber breakage.
Implementation Method 1
a continuous high shearing device that applies a shear force to a high molecular weight polymer serving as a raw material by rotation of a screw to reduce the molecular weight
Implementation Method 2
a hot air supply part that supplies hot air to the polymer extruded from the die and stretches the polymer in a fibrous form
Data Source
AI summary
A production device for melt-blown non-woven fabric, with which a high molecular weight polymer can be reduced in molecular weight by applying a shear force to the high molecular weight polymer without adding an additive such as a peroxide that promotes thermal decomposition reaction, and a low molecular weight polymer can be efficiently produced. The low molecular weight polymer and the melt-blown non-woven fabric are produced using a continuous high shearing device that applies a shear force to the high molecular weight polymer serving as a raw material by rotation of a screw body 37 to reduce the molecular weight of the high molecular weight polymer so as to obtain a low molecular weight polymer, and cools the low molecular weight polymer by passing the low molecular weight polymer through a passage 88 arranged in the axial direction inside the screw body 37.