Filter medium comprising a melt-blown nonwoven, and its use
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Solution Overview
Problem
Current filter media, particularly those using meltblown nonwovens, face issues with mechanical strength, porosity, air permeability, and electrostatic charging limitations, leading to short service life and unsuitability for food applications due to chain degradation and hydrolysis concerns with thermoplastic polyurethane materials.
Innovation Solution
A filter medium comprising a first ply of a meltblown nonwoven made from a combination of styrenic thermoplastic elastomers and polyolefins, which enhances mechanical strength, flexibility, and electrostatic charging capabilities while being resistant to hydrolysis and suitable for food applications, with specific ratios and additives to optimize properties for various uses such as coffee filters, facemasks, and compressed air filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermoplastic polyurethane meltblown nonwoven is used, then elasticity and comfort are improved, but mechanical strength and stability deteriorate due to chain degradation and hydrolysis
Solution Approach 1:
The patent uses composite materials by combining polyolefin fibers (providing mechanical strength and hydrolysis resistance) with elastomeric components (providing elasticity and comfort). This composite structure allows the filter medium to simultaneously achieve the desired comfort properties and mechanical stability without the degradation issues of pure thermoplastic polyurethane.
2Manufacturing precision
If single-ply filter media with surface densification is used, then coarse dust filtration is improved, but fine dust penetration increases and service life decreases
Solution Approach 1:
The patent applies local quality by creating a multi-ply structure where different layers have different pore sizes and filtration functions. The first ply has smaller pores for fine dust capture, while subsequent layers have larger pores for structural support and coarse dust filtration. This allows each layer to optimize its local function, preventing fine dust penetration while maintaining service life.
Solution Approach 2:
The patent segments the filter medium into multiple plies with distinct functions. The first ply is optimized for fine dust filtration with smaller pores, while subsequent plies provide mechanical strength and coarse dust capture. This segmentation allows the filter to handle both fine and coarse dust effectively, extending service life compared to single-ply designs.
3Manufacturing precision
If meltblown nonwoven with small fiber diameter is used, then fine dust filtration is improved, but mechanical strength and abrasion resistance deteriorate
Solution Approach 1:
The patent solves the mechanical strength problem by transitioning from a two-dimensional single-layer structure to a three-dimensional multi-ply construction. The fine dust filtration function is concentrated in the first ply with small fiber diameter, while the mechanical strength is provided by subsequent plies with larger fibers and different structural characteristics, effectively separating these conflicting requirements into different spatial dimensions.
4Manufacturing precision
If electrostatic charging is applied to meltblown nonwoven, then filtration efficiency is improved, but dendrite formation increases causing blockage
Solution Approach 1:
The patent uses an intermediary approach by applying electrostatic charging selectively to specific layers or regions of the multi-ply filter medium rather than uniformly to the entire structure. This allows the charged regions to enhance filtration efficiency for fine dust particles while the uncharged structural plies provide mechanical support and prevent dendrite-induced blockage.
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 improved mechanical strength, flexibility, and electrostatic charging, extending service life and ensuring suitability for food applications by using styrenic thermoplastic elastomers and polyolefins, maintaining air permeability, and meeting standards for facemasks and other filtration needs.
Implementation Method 1
In order to remove solid impurities, for example dust particles, from liquids and gases, there are essentially two different types of filter media. The first type is depth filter media, which are constructed such that they able to absorb and store a maximum amount of dust before becoming blocked.
Implementation Method 2
A filter medium comprising a first ply of a meltblown nonwoven, wherein the meltblown nonwoven comprises a) at least one styrenic thermoplastic elastomer and b) at least one polyolefin
Data Source
AI summary
Provided herein is a filter medium comprising a first nonwoven melt-blown layer, the meltblown nonwoven comprising a) at least one styrenic thermoplastic elastomer and b) at least one polyolefin. Also provided herein is the use of the filter medium for coffee filters, compressed air filters and face masks.