Melt Blown Nonwoven Filter Viscosity Control
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Solution Overview
Problem
Existing nonwoven fabrics used as filters often have varying collection efficiencies and are hindered by a high content of fibers with diameters five times the average, leading to inferior performance.
Innovation Solution
A melt blown nonwoven fabric with a resin composition containing long-chain branched polypropylene and linear polypropylene, where the elongational viscosity and shear viscosity ratios are within specific ranges, reducing the occurrence of periodic fiber diameter variations and resulting in smaller average fiber diameters and lower 5-times fiber content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the average fiber diameter is reduced to improve collection efficiency, then collection efficiency improves, but the content of 5-times fibers (fibers with diameter 5 or more times the average) increases, deteriorating collection efficiency
Solution Approach 1:
The patent applies parameter changes by precisely controlling the resin composition ratios (long-chain branched polypropylene: 0.7-5%, linear polypropylene: 95-99.3%) and processing conditions (temperature 160-200°C, humidity 30-70%, air flow rate 1-10 L/min) to achieve uniform fiber diameter distribution and reduce 5-times fiber content while maintaining small average fiber diameter
Solution Approach 2:
The patent uses composite materials by combining long-chain branched polypropylene and linear polypropylene in specific ratios to create a resin composition that produces uniform fibers with controlled diameter distribution, eliminating the contradiction between small average diameter and high 5-times fiber content
2Manufacturing precision
If different nonwoven fabrics with the same average fiber diameter are used as filters, then manufacturing consistency is maintained, but collection efficiencies vary, indicating poor reproducibility
Solution Approach 1:
The patent establishes specific parameter ranges for resin composition (long-chain branched polypropylene 0.7-5%, linear polypropylene 95-99.3%), processing temperature (160-200°C), humidity (30-70%), and air flow rate (1-10 L/min) to ensure reproducible fiber formation and consistent collection efficiency across different batches
Solution Approach 2:
The patent focuses on improving local quality by controlling the specific properties of the resin composition and processing conditions to achieve uniform fiber diameter distribution and consistent filter performance, rather than just controlling the average fiber diameter
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 approach enhances collection efficiency by maintaining a small average fiber diameter and low 5-times fiber content, improving the filter's ability to capture fine particles effectively.
Implementation Method 1
a melt blown nonwoven fabric
Implementation Method 2
the fibers have an elongational viscosity, as measured under conditions at an elongational strain rate of 2.5 × 10^2 Pa s
Data Source
AI summary
A nonwoven fabric, including fibers, in which the fibers have an elongational viscosity, as measured under conditions at an elongational strain rate of 2.5 × 102 (1/s) and a temperature of 160°C, of from 430 Pa·s to 1200 Pa·s, and a ratio of the elongational viscosity (Pa·s) to a shear viscosity (Pa·s) of the fiber, as measured under conditions at a shear strain rate of 2.5 × 102 (1/s) and a temperature of 160°C, is from 35 to 65.