HK1056335A1 - Impregnated micro-fiber filtration unit - Google Patents

Description

Impregnated microfiber filter unit

Technical Field

The invention relates to a filter unit, in particular for use in a cartridge or bag-type microfibre unit, said cartridge or bag having a stack of layers of fibrous material and an active substance applied between the stacks.

Background

Filtration units as described in us patent nos 3816304, 4902427, 5389166 and 5679251, wherein the active substance is dispersed internally in the fibrous material. The manufacture of cartridges or filter bag type filter units from blown microfiber material is both economical and extremely efficient. One example of such a unit is described in us patent No4983292, the contents of which are incorporated herein by reference. However, to date, no teaching has been made to combine active materials with such blown microfiber units. The active substance is usually added in the form of a powder or small particles. When the active is added to the stream of blown microfibers, the air stream along with the microfibers blows the active away so that the active is not deposited onto the blown fiber bundle.

Disclosure of Invention

In the present invention, it was found that: if the direction of the flow of fibrous material is changed in the transverse direction, the air flow is interrupted, allowing the active substance to be deposited on the bundle of material before reaching the rotating cylinder on which the filtering unit is formed. In this way, the active substance is sandwiched between layers of fibre material bundles which are integrated by fusion, leaving the active substance in the formed filter unit.

It is therefore an object of the present invention to provide a blown microfiber filter unit having an active substance dispersed therein.

It is another object of the present invention to provide a method of forming a blown microfiber filter unit having a layer of active material.

It is a further object of the present invention to provide a filter unit formed with active substances which is economical to manufacture.

Other objects of the invention will become apparent upon reading the following specification.

Brief description of the drawings

A preferred embodiment of the invention is selected wherein:

FIG. 1 is a cross-sectional view of a filtration unit showing the active material layers within the unit;

fig. 2 is a side view of the filter unit formed in fig. 1.

Description of the preferred embodiments

Fig. 1 is a cross-section of a filter unit 10 comprising a multiple fused stack of substrates 12 in which an active substance 14 is in the form of a layer. The unit 10 is shown in the figures in the form of a cylinder, referred to in the industry as a cartridge filter. However, it is to be understood that the invention is also applicable to pocket filters. The unit 10 has an air core 16. The outermost and innermost layers of the cell 10 are preferably formed of only the base material so as to coat the active material 14 dispersed or sandwiched between the base material layers in the central portion of the cell. The substrate 12 is preferably a blown microfiber such as polypropylene fiber. The active substance 14 may be composed of a variety of substances selected depending on the intended use of the filter unit, such as irrigation, fertilization, disinfection, or cleaning. For example, for filtering water, the active substance may be carbon particles.

Fig. 2 is a method of making the filter unit of fig. 1. A nozzle 18 and a rotary drum 20 are provided. Typically, in the manufacture of cartridge filters, the liquefied and molded substrate is blown by a nozzle 18 into an elongated bundle of fibers that are wound onto a rotating drum 20, with spaced bonding occurring between the tows as the heated bundle is wound onto the rotating drum 20. This gives the filter unit a porous character. Once the material on the rotating drum 20 reaches the desired thickness, the fiber bundle ejection from the nozzle 18 is stopped and the wound laminated fiber unit is removed from the rotating drum. The elongated unit is then cut to the desired length in the longitudinal direction and suitably packaged.

In the present invention, the channel of the blown substrate 12 can be interrupted, for example, by a lateral shift of the roller 22. When the base material ejected from the nozzle interrupts or changes direction the air flow accompanying the fiber bundle due to this displacement. A dispensing nozzle 24 is positioned between the roller 22 and the rotating drum 20 deposit, such as by gravity or otherwise, to cause the active substance 14 to be layered or deposited onto the substrate 12 tow. The controlled flow of active material 14 is deposited onto the substrate tow without being disturbed or interrupted by the flow of air from the nozzle 18 due to redirection of the tow by the roller 22. The substrate 12 with the active material 14 layer is then wound onto a rotating drum 20 such that the active material remains between the adhesive layers of the substrate as they cool on the rotating drum 20. Generally, the filter unit 10 is formed by: several layers of the substrate 12 are first wound on a rotating drum and then the active material 14 is added. Just before the final diameter of the filter unit is reached, the addition of active substance 14 to the substrate tow is stopped so that several bundles of material, just substrate, are wound onto the outer layer of the filter unit. The active substance is in this way confined between the layers of pure substrate which can be used as a prefilter.

The unit 10 shaped as an elongated cylinder can be wrapped with shrink wrap plastic applied to the elongated cylinder unit 10 before or after the unit 10 is removed from the rotating cylinder 20. The unit is then cut to specific lengths once it is removed from the rotary drum 20. In this way, the outside of the filter unit can be kept clean and active substances do not migrate to the outside of the unit.

The above-described subject matter of the invention is not limited to the details described above, but may be varied within the scope of the appended claims.

Claims (7)

1. A method of making a filter unit comprising the steps of:

a. providing a liquefied and molded substrate;

b. the substrate is passed through a nozzle to form a plurality of elongated intermingled tows;

c. winding the tow in a self-bonding overlapping manner on a rotating drum to form a filter unit;

d. changing the direction of the material beam transversely relative to the direction of the material beam issuing from the nozzle at a location between the nozzle and the rotating drum; and

e. depositing an active material onto the material beam between the location and the rotating drum.

2. The method of claim 1, wherein the active material is carbon.

3. The method of claim 2, wherein the substrate is plastic.

4. The method of claim 3, wherein the substrate is polypropylene.

5. A method according to claim 1, wherein said step e forms an elongated cylindrical filter unit, then wraps said filter unit while still on said cylinder with a wrapping material, removes said wrapped filter unit from the cylinder, and cuts it into modules of selected length.

6. The method of claim 1, wherein said step e is: continuously winding the material tow onto the rotating drum, causing the active material to be discontinuously deposited onto the material tow, forming a multi-tow material with only the substrate outside the unit.

7. A method of making a filter unit comprising the steps of:

a. providing a liquefied and molded substrate;

b. the base material is sprayed out of the nozzle under the action of air flow to form a plurality of long and narrow tows which are mixed with each other;

c. winding the tow in a self-bonding overlapping manner on a rotating drum to form a filter unit;

d. after leaving the nozzle, interrupting the air flow at a location between the nozzle and the rotating cylinder by changing the direction of the fibrous material stream in the transverse direction;

e. depositing an active material onto the material tow between the location and the rotating drum.