Blended Nonwoven Filter Medium Reducing Pressure Drop
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Solution Overview
Problem
Filter media with porous fluororesin membranes experience high pressure drops due to limited fluid passage at the interface between the membrane and the nonwoven fabric, which increases energy consumption during filtration.
Innovation Solution
A filter medium comprising a porous fluororesin membrane laminated with a blended nonwoven fabric containing core-sheath fibers with a polyester core and polyolefin sheath, polyester fibers, and copolymerized polyester sheath fibers, reducing the number of bonding portions during heat lamination to minimize pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an air-permeable support member is laminated on a porous fluororesin membrane to provide rigidity, then the filter medium becomes resistant to deformation, but the pressure drop increases due to limited fluid passage at the interface
Solution Approach 1:
The support member is designed with porous structure (porosity of 30% or more) that allows fluid to pass through rather than being blocked at the interface. The porous structure maintains mechanical strength while enabling efficient airflow, resolving the contradiction between needing rigidity and minimizing pressure drop.
Solution Approach 2:
The invention uses a composite structure combining porous fluororesin membrane with a porous support member made of specific fiber blends (polyester, polyolefin, and their core-sheath combinations). This composite material approach allows the support member to provide structural rigidity while maintaining high air permeability through careful selection of material properties and porosity.
2Strength
If heat lamination is used to bond the nonwoven fabric to the porous fluororesin membrane, then the layers are firmly attached, but the number of bonding portions limits fluid passage and increases pressure drop
Solution Approach 1:
The support member maintains high porosity (30% or more) even after heat lamination bonding. The bonding process is designed to attach layers while preserving the porous structure, allowing fluid to pass through the bonded interface without significant resistance.
Solution Approach 2:
The invention optimizes parameters including fiber composition (specific ratios of polyester, polyolefin, and core-sheath fibers), fineness (1-10 dtex), and porosity (30% or more) to achieve a balance between bonding strength and fluid passage capability. The copolymerized polyester with specific glass transition temperature ranges is used to control bonding characteristics.
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 results in a filter medium with a lower pressure drop and maintained collection efficiency, suitable for use in vacuum cleaners and other applications requiring low energy filtration.
Implementation Method 1
at least a portion of the polyolefin sheath of the core-sheath fibers (A) melts and allows the porous fluororesin membrane and the blended nonwoven fabric to be laminated together
Data Source
AI summary
The present invention provides a filter medium causing a low pressure drop. The present invention is a filter medium including a porous fluororesin membrane and an air-permeable support member laminated on at least one surface of the porous fluororesin membrane. In this filter medium, the air-permeable support member is a blended nonwoven fabric containing: core-sheath fibers (A) having a polyester core and a polyolefin sheath; polyester fibers (B); and core-sheath fibers (C) having a polyester core and a copolymerized polyester sheath.