CS247738B1 - High-efficient filtration non-woven fabric - Google Patents

Abstract

It is a high performance nonwoven filter an aerosol-separating fabric of gas and its essence is that it is composed in the thickness direction of the three bands, both of them the outer bands are identical and consist of staple ends and zone-internal denser than the outer bands, it consists only of staple fibers intertwined, lying predominantly horizontal while a minority of these fibers are part of theirs the length of the inner band and produces a number of predominantly vertical bundles bound fibers that are uniformly distributed spaced throughout the inner zone and combine polypropylene or polyester polypropylene textile material in one a planar formation, but which faces the surface of both outer hair bands loose to the rest of the individual fiber lengths oriented mainly in one direction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high performance filter nonwoven fabric for separating an aerosol from a gas, in particular a water aerosol and water droplets from atmospheric air in an aircraft air conditioning system, consisting of synthetic, especially polypropylene fibers and a collision formation.

Aircraft separator is used for air-conditioning of aircraft instruments. Until now, a filter fabric manufactured in accordance with the invention protected in Czechoslovakia AO 217 208 has been used, which typically retains 50-70% of the precipitated water from the air stream in the condensation pad at a minimum airflow of 520 kg per hour. The increased parameters of aircraft innovation were also reflected in the requirements for increased parameters of the condensation pad, which must capture 80 to 100% of the precipitated water from the air stream at a higher airflow rate of 635 kg per hour.

Disadvantages of the presently used filter fabrics produced according to the invention, protected in Czechoslovakia AO 217 208, which are in particular lower filter parameters, are eliminated by the high-performance filter nonwoven fabric according to the invention, consisting of synthetic, especially polypropylene fibers or blend of polyester and polypropylene fibers the structure of which is composed of three zones in the thickness direction, the two outer zones being identical and consisting of the ends of the staple fibers and the inner zone, denser than the outer zones, consisting solely of staple fibers of various entanglement, predominantly a horizontal direction, while a minority of these fibers are stretched through the inner band thickness over a portion of their lengths to form a majority of predominantly vertical bundles of binder fibers that are uniformly distributed throughout the inner surface area and combine the polypropoylene or polyesterpolypropylene textile material into a single sheet, but which are spaced towards the surface of the two outer pile strips into the remainder of the individual fiber lengths oriented predominantly in one direction. A further aspect of the high performance filter nonwoven fabric of the present invention is that the bulk density of the entire body is 90-110 kg. m ³ , while for the inner zone it is 120 to 150 kg. m ^-3 , and also consists of polypropylene fibers and / or a blend of polyester and polypropylene staple fibers containing 30 to 50% by weight of coagulated polypropylene fibers having a nominal weight in the range of 1.3 to 2.8 dtex .

The outer pile zone at the inlet side of the filter fabric captures a greater amount of water from the flowing air, while the inner pile zone captures a smaller amount of water, but in the form of a fine water aerosol. The higher the density of the inner band greatly increases its separation ability. The outer pile band at the outlet side of the filter fabric ensures a uniform distribution of the air flow as it exits the water separator, thereby achieving a desired pressure drop of 5 kPa at a flow rate of 635 kg air per hour.

Example 1

The high performance filter nonwoven fabric of the present invention is prepared as follows: Two fiber webs, each weighing 270 g / m ^{2 each} , are made up of a blend of polypropylene staple fibers containing 50 weight percent of 1.3 dtex shrinkage fibers and a length of 38 mm. weight percent of fixed fibers of 1.7 dtex and 38 mm in length; and 25 weight percent of fixed fibers of 2.8 dtex and 60 mm in length. Each fleece is a pre-sing, not less than 35 punctures / cm ² .

During stitching, two pre-reinforced nonwovens are laid on top of each other, and the formation having an average basis weight of 540 g / m ² is stitched on both sides with an intensity of 580 stitches per cm ² , approximately half of the stitches on one side and the other half . The basis weight of the needling fabric is 300 grams per m ² and is then thermally precipitated with warm air of 165 ° C until the surface shrinkage is 50% on average.

The needled and precipitated formation is then combed with 8 to 12 passes through the combing machine, the number of passes being valid for each combed side of the formation. During the combing, a plurality of fiber ends are pulled out, and the ends of the binder fiber bundle are disengaged from the needled precipitated formation.

A truncated cone-shaped condensation liner is used for water separators of air-conditioning systems of the air-conditioning filter fabric manufactured from 400 to 450 g / m ² and 5 mm thick. The lifetime of this cladding pad is at least 200 flight hours.

Example 2

The manufacture of filter fabric differs from Example 1 only in the material composition and the needling nature. A single-layer fibrous pre-consolidated formation having a basis weight of 550 g / m ² is formed, consisting of a blend of staple polyester and polypropylene fibers, containing 70% by weight of polyester fibers having a fineness of 1.7 dtex and 38 millimeters in length and 30% by weight of polypropylene shrinkable fibers of fineness 1,3 dtex and 38 mm length.

The textile formation is stitched on both sides with a total specific number of 420 stitches per cm ² , with both binder fibers passing through the entire thickness of the fabric from one side to the other. The basis weight of the needle-punched fabric is 330 g per m ² and the heat is precipitated by heat air of 156 ° C until the shrinkage exceeds 55 ° / o.

The needled and precipitated formation is further combed with 6-14 passages through a combing machine from each side. The fabric then has a basis weight of 500 to 580 g / m ² and a thickness of 5 to 6 mm from which the condensation pad is sewn as in Example 1.

Claims (1)

High-performance filter nonwoven consisting of synthetic, in particular polypropylene fibers, or a blend of polyester and polypropylene fibers forming a needlepunch, consisting of three bands in the thickness direction, an inner zone and two outer zones, both outer zones being identical and are formed from the ends of the staple fibers, characterized in that the inner band is denser than the outer zone and consists solely of staple variously entangled fibers lying predominantly in a horizontal direction and a minority of ^one fiber portions of their lengths proVYNÁLEZU pulled thicknesses of the inner band and creates a number of predominantly vertical bundles of binder fibers which are uniformly distributed over the entire surface of the inner band and connect the fibrous material into one sheet, but which are spaced apart towards the surface of the two outer bands The polypropylene fibers or the blend of polyester and polypropylene staple fibers contain 30 to 50% by weight of precipitated polypropylene fibers having a fineness in the range of 1.3 to 2.8 dtex.