FILTERING MATERIAL FOR FINE PURIFICATION OF OILS AND FUELS, METHOD OF PRODUCTION AND APPLICATION THEREOF Russian patent published in 2020 - IPC B01D39/16 D01F1/00 D01F6/94 

FIELD: technological processes.

SUBSTANCE: invention relates to production of nonwoven filtration materials from polymer microfibres, preferably used for filtration of oils and fuels in aircraft engineering and fuel supply systems. Filtering material comprises a layer of polymer microfibres obtained by electroforming, placed between two layers of a non-woven substrate of polyester fibers. Microfibres are made from resin-cured phenol-formaldehyde resin of resol type with addition of polyvinyl butyral in amount of 7 % of weight of dry substance and have average optical diameter of 0–2.0 mcm, wherein the microfiber layer weight per unit area is 4.6 g/m²_. Filtration material has a fibrous-porous structure of microfibres fastened at intersections with porosity not less than 80 % at average pore diameter of 1–8 mcm and aerodynamic resistance to air flow of 15–100 Pa at linear flow rate of 1 cm/s. Material is obtained by aerodynamic electroforming from solution of phenol-formaldehyde resin of resol type with addition of polyvinyl butyral in amount of 7 % of weight of dry substance in mixture of ethyl alcohol and ethyl acetate in ratio 1/1–8/1 by weight at total concentration of molding solution of 8–15 wt. %, with addition of curing agent - paratoluenesulphonic acid - in amount of 3–5 % of dry substance weight. Electroforming is performed in electrostatic field with intensity from 1 to 3 kV/cm, distance between electrodes is 10–30 cm, at temperature in electroforming zone is 20–30 °C and relative humidity of 30–50 %. Volume flow of molding solution is set to 30–100 ml/h through one nozzle, and volumetric flow rate of air 25–40 l/min through one nozzle. After electrospacing filtering material is duplicated by filtering layer inside and subjected to heat treatment for 24 hours at temperature of 50 °C for removal of residual solvent, and then for 10 hours at temperature of 70 °C for conversion of phenol-formaldehyde resin into reticol, after which filtering material is calendered at shaft temperature of 105–115 °C and pressure of 0.3 MPa for bonding fibers and layers to each other, and then subjected to successive thermal treatment in following mode: 24 hours at temperature 90 °C; 12 hours at 110 °C; 12 hours at temperature 120 °C for hardening of phenol-formaldehyde resin in resite. Invention provides the possibility of fine cleaning of oils and fuels in aircraft engineering and fuel supply systems at medium temperature up to 140 °C of suspended particles.

EFFECT: technical result is improved physical and mechanical properties.

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