Tetrafluoroethylene Polymer Air Filter Medium Uniform Pressure Loss
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Solution Overview
Problem
Existing tetrafluoroethylene polymer-based air filter media face challenges in achieving uniform pressure loss across multiple positions while minimizing overall pressure loss.
Innovation Solution
A tetrafluoroethylene polymer with a specific heat-of-fusion curve ratio (S2/S1 ≥ 0.60) and half-width ≥ 5.0, combined with a standard specific gravity of 2.140 to 2.165, which enhances drawability and non-melt processability, resulting in improved film uniformity and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tetrafluoroethylene polymer is used to produce air filter medium, then the production process is simple, but the pressure loss is uneven at multiple positions and the overall pressure loss is high
Solution Approach 1:
The patent changes the molecular weight distribution parameters of the tetrafluoroethylene polymer by controlling the ratio S2/S1 (endotherm in range T0-350°C to endotherm in range 320-T0°C) to be 0.60 or more, and the half-width HW to be 5.0 or more. This parameter optimization ensures uniform pressure loss distribution across the air filter medium while maintaining low overall pressure loss, directly resolving the contradiction between pressure loss uniformity and energy loss.
2Strength
If tetrafluoroethylene polymer with high molecular weight is used, then the strength is improved, but the drawability deteriorates due to early extension of low-molecular-weight portions
Solution Approach 1:
The patent optimizes the molecular weight distribution by controlling the ratio S2/S1 ≥ 0.60 and half-width HW ≥ 5.0, which balances the proportion of high-molecular-weight polymers (providing strength) and low-molecular-weight polymers (providing drawability). This parameter control prevents early extension during drawing while maintaining adequate film strength, resolving the contradiction between strength and drawability.
3Loss of energy
If the molecular weight distribution is widened, then the pressure loss is reduced, but the film uniformity deteriorates due to early extension
Solution Approach 1:
The patent achieves both reduced pressure loss and maintained film uniformity by precisely controlling the molecular weight distribution parameters: S2/S1 ratio ≥ 0.60 and half-width HW ≥ 5.0. This specific parameter range ensures that the polymer has sufficient high-molecular-weight content for low pressure loss while limiting the excessive low-molecular-weight content that would cause early extension and non-uniformity, thus resolving the contradiction between pressure loss reduction and film uniformity.
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 ensures a uniform pressure loss distribution across the air filter medium, achieving a coefficient of variation of 5% or less and high collection efficiency for NaCl particles, with pressure loss reduced to 250 Pa or less at a flow velocity of 5.3 cm/s.
Implementation Method 1
On a heat-of-fusion curve, S2 represents an endotherm (mJ/mg) in a range of T0° C. or higher and 350° C. or lower and S1 represents an endotherm (mJ/mg) in a range of 320° C. or higher and T0° C. or lower
Data Source
AI summary
A tetrafluoroethylene polymer is provided in an air filter medium having a pressure loss that can be reduced and made uniform at a plurality of positions. The tetrafluoroethylene polymer may also be provided in an air filter medium, a filter pack, or an air filter unit. The tetrafluoroethylene polymer has drawability and non-melt processability. The tetrafluoroethylene polymer has a ratio S2/S1 of 0.60 or more, where S2 represents an endotherm mJ/mg in a range of T0° C. or higher and 350° C. or lower, T0° C. is a temperature 2.5° C. lower than a temperature Tp° C. (340≤Tp≤345) at which a minimum point is given on a heat-of-fusion curve obtained by measuring an unbaked polymer for measurement having no history of heating to a temperature of 300° C. or higher using a differential scanning calorimeter at a temperature-increasing rate of 2° C./min, and S1 represents an endotherm mJ/mg in a range of 320° C. or higher and T0° C. or lower.