Low-Basis-Weight Air Filter Media Using Composite Fibers
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Solution Overview
Problem
Existing air filter media with low basis weight suffer from decreased internal tearing strength and water repellency, making them prone to breakage during pleat processing and practical use, and requiring high costs for water repellency enhancement.
Innovation Solution
A filter medium composed of glass short fibers and hydrophobic chemical synthetic fibers with a fiber diameter of 5 µm or less, bonded by a hydrophobic synthetic resin-based binder, achieving a mass ratio of 70/30 to 95/5, and a basis weight of 25 to 50 g/m², which imparts flame retardancy and maintains internal tearing strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the basis weight of the filter medium is reduced to decrease the thickness of the air filter unit, then the depth and weight of the filter unit are reduced, but the internal tearing strength and water repellency of the filter medium deteriorate, causing breakage during pleat processing and practical use
Solution Approach 1:
The patent applies composite materials by combining glass fibers (65-95 mass%) with synthetic binder fibers (5-35 mass%), specifically using vinylon fibers with controlled water solubility. This composite structure provides both the low basis weight needed for thin filter units and the enhanced internal tearing strength required to prevent breakage during pleat processing and use.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the water solubility characteristics of the vinylon binder fibers (water solubility of 5-50 mass%) and adjusting the incorporation percentages of different fiber components. These parameter optimizations enable the filter medium to maintain adequate strength at reduced basis weights while controlling pressure loss and improving collection efficiency.
2Volume of moving object
If the basis weight of the filter medium is reduced to decrease the thickness of the air filter unit, then the depth and weight of the filter unit are reduced, but the water repellency of the filter medium deteriorates, requiring high costs for water repellency enhancement
Solution Approach 1:
The patent applies self-service by utilizing the inherent water-repellent properties of vinylon fibers, which naturally resist water penetration without requiring additional water repellent coatings or treatments. The vinylon binder fibers themselves provide the water repellency function, eliminating the need for separate water repellent enhancement processes and associated costs.
3Reliability
If the incorporation percentage of glass fibers is increased to improve collection efficiency, then the filtration performance is improved, but the internal tearing strength decreases due to the brittle nature of glass fibers
Solution Approach 1:
The patent applies composite materials by creating a synergistic mixture where glass fibers (65-95 mass%) provide high collection efficiency through their fine diameter and large surface area, while vinylon binder fibers (5-35 mass%) provide mechanical strength and flexibility. The composite structure allows the brittle glass fibers to be held together by the more ductile vinylon fibers, maintaining both filtration performance and structural integrity.
Solution Approach 2:
The patent applies the intermediary principle by using vinylon binder fibers as a mediating component that connects and reinforces the glass fiber network. The vinylon fibers act as an intermediary material that transfers and distributes mechanical stresses, preventing stress concentration at glass fiber fracture points and thereby enhancing the overall internal tearing strength of the filter medium.
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 solution significantly improves internal tearing strength and water repellency while conforming to flame retardancy standards, ensuring the filter medium's integrity and performance at reduced basis weights.
Implementation Method 1
bonded by a hydrophobic synthetic resin-based binder
Implementation Method 2
hydrophobic synthetic resin-based binder
Data Source
AI summary
An object of the present invention is to improve a problem of the decrease in the internal tearing strength and water repellency in accordance with the decrease in the basis weight of a filter medium for air filters, and to provide a filter medium for air filters that can also address a demand for flame retardancy. The low-basis-weight filter medium for air filters according to the present invention is characterized by glass short fibers (A) and short fibers of hydrophobic chemical synthetic fibers each having a fiber diameter of 5 µm or less (B), as raw material fibers of the filter medium, by a mass ratio (A/B) in the range of from 70/30 to 95/5; a hydrophobic synthetic resin-based binder is added to the filter medium by 3 to 10 parts by mass of with respect to 100 parts by mass of the raw material fibers; and the filter medium has a basis weight of from 25 g/m2 or more to 50 g/m2 or less.