Wet-Laid Filter Medium With Reinforcing Layer
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Solution Overview
Problem
Conventional filter media for liquid filtration in wire electrical discharge machines face issues with bursting strength when wetted, leading to reduced efficiency and increased downtime due to high pressures, and existing solutions either compromise on filter efficiency or require costly process modifications.
Innovation Solution
A filter medium with a basis weight of 100 g/m2 or less, formed using wet type paper-making and treated with a synthetic resin binder to maintain strength and uniform pore distribution, reducing the decline in bursting strength and improving filtration precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the filter medium basis weight is decreased to reduce sheet thickness, then the total filter medium area increases and filter medium life is extended, but the bursting strength when wetted decreases
Solution Approach 1:
The patent uses a composite structure consisting of a filter medium layer and a reinforcing layer. The filter medium layer has a basis weight of 100 g/m2 or less with micropores for filtration, while the reinforcing layer contains continuous fibers (glass fibers, metal fibers, or organic fibers) that provide tensile strength and bursting strength when wetted. This composite structure allows the filter medium to maintain high filter area while achieving the required bursting strength of 200 kPa or more when wetted.
2Manufacturing precision
If the sheet thickness is decreased while keeping basis weight constant, then the filter medium becomes tighter with higher filtering resistance, but the filter medium life is reduced
Solution Approach 1:
The patent applies local quality by creating different structural zones within the filter medium. The filter medium layer has a controlled basis weight of 100 g/m2 or less with specific micropore structures optimized for particle capture, while the reinforcing layer provides mechanical strength without interfering with filtration. This localized functional differentiation allows the filter medium to achieve both high filtration precision and extended service life without increasing overall sheet thickness.
3Strength
If polyester non-woven fabrics with high basis weight are used, then the bursting strength is sufficient, but the total filter medium effective area becomes small
Solution Approach 1:
The patent segments the filter medium into two distinct functional layers: a filter medium layer with basis weight of 100 g/m2 or less that provides the filtration surface area, and a separate reinforcing layer that provides the necessary mechanical strength. This segmentation allows each layer to be optimized independently - the filter medium layer can be made thin and lightweight to maximize effective filtration area, while the reinforcing layer compensates for the reduced basis weight by providing bursting strength of 200 kPa or more when wetted.
4Duration of action of stationary object
If the filter medium is pleated to increase total area, then the filter medium life is extended, but the structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The patent changes the fundamental parameter of filter medium design by using a lightweight base material (basis weight of 100 g/m2 or less) combined with a reinforcing layer, which enables the medium to achieve high effective area through pleating without compromising strength. The reinforcing layer with continuous fibers maintains structural integrity during pleating and incorporation into the filter unit, allowing complex pleated configurations to be manufactured while extending filter medium life through increased total filtration area.
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 filter medium achieves high wet bursting strength, improved filtration precision, and reduced production costs by maintaining strength and uniformity, allowing for increased filter life and efficiency without the need for extensive process modifications.
Implementation Method 1
a filter medium for liquid filtration characterized by having a 100 g/m2 or less basis weight, a 30% or less strength decrease ratio as calculated from the normal state bursting strength and the bursting strength when wetted in water
Implementation Method 2
formed using wet type paper-making and treated with a synthetic resin binder to maintain strength and uniform pore distribution
Implementation Method 3
a filter medium for liquid filtration that separates and captures particulates contained in liquid
Data Source
AI summary
A filter medium for liquid filtration of fine texture exhibiting high strength when wetted with water, which filter medium is comprised of a wet-laid nonwoven fabric. There is provided a filter medium for liquid filtration comprised of a wet-laid nonwoven fabric, characterized in that through blending of 0.5 to 40 wt. % of unbeaten natural fibers, it exhibits a very fine texture, a lowering ratio, calculated from bursting strength in ordinary state and bursting strength when wetted with water, of 30% or below, and a bursting strength, had when wetted with water, of 300 kPa or greater.