GB1594700A

GB1594700A - Pleated filtering material

Info

Publication number: GB1594700A
Application number: GB3069577A
Authority: GB
Original assignee: Marshall D A G
Current assignee: Marshall D A G
Priority date: 1978-05-25
Filing date: 1978-05-25
Publication date: 1981-08-05

Description

(54) PLEATED FILTERING MATERIAL (71) I, DENNIS ALBERT GEORGE MARSHALL, a British Subject, of "Greets Cottage", Friday Street, Warnham, Near Horsham, Sussex, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pleated filtering material and to a method and apparatus for producing pleated filtering material.

In many filters for filtering air or other gaseous streams (and especially in so-called "high-efficiency" filters) it is frequently desirable or necessary to use filtering material which is in pleated form. Where the fil terinz material has an inherent stiffness or rigidity, or is bonded to a stiff or rigid layer, it is not too difficult to ensure that the filtering material holds its pleats with the correct spacing between adjacent pleats, but this is not possible where the filtering material is liable to lose its pleats because of an inherent springiness or an inherent limpness. This is the case, for example, where the filtering material comprises filter paper, micro-glass paper, synthetic plastics open-pore foam material, or a random fibre mat. It has, accordingly, already been proposed to provide pleat-spacers by applying a selfhardening viscous liquid or paste to the surface of the filtering material.

The aim of the present invention is to simplify the manufacture of pleated filtering material by using pleat-spacers which are applied in solid form, and according to the invention this is achieved by providing a pleated filtering material for filtering air or other gaseous streams with pleat-spacers in the form of spaced-apart strips, tapes or ribbons of a solid synthetic plastics material or of resin-impregnated paper or of aluminium foil each of which adheres over its full length to the filtering material itself by virtue of an adhesive applied to the pleat-spacer before it is brought into contact with the filtering material.

The invention also extends to a method of making such filtering material and to apparatus for carrying out that method.

A specific example of filtering material in accordance with the invention and apparatus for making it will now be described with reference to the accompanying drawings, in which: Figure 1 shows the apparatus diagrammatically; Figure 2 is a plan view of the filtering material prior to pleating; and Figure 3 is a perspective view of the finally-produced pleated filtering material.

The apparatus shown in Figure 1 comprises a roll 10 of filtering material in sheet form. This can be, for example, filter paper, glass fibre paper, open-pore polyurethane foam in sheet form, a random fibre mat or some other filtering material which is available in sheet form. The filtering material is drawn off the roll towards a driven roller 12, there being suitable means (not shown) to guide the material between the roll 10 and the roller 12.

After leaving the roll 10, the material has a number of parallel, pleat-spacing, adhesive strips 14 from rolls 16 applied to it at a pair of nipping rollers 18 and 20, the rolls 16 being carried on a single roller. These strips are about 1 mm wide and less than 1 mm deep (e.g., about 0.68 mm deep) and comprise solid tapes or ribbons of a synthetic plastics material such as a polyester or PVC, or of resin-impregnated paper or aluminium foil. They are applied to the filtering material so that the strips are 20-45 mm apart.

Adhesive is applied to the strips 14 before they are wound to form the rolls 16. If desired, the adhesive can be so applied to the strips that, after application of the strips to the filtering material, adjacent folds of each pleat-spacing strip adhere to each other, thereby holding the pleats in the filtering material.

After the sheet filtering material nas moved past the rollers 18 and 20, it passes round the roller 12 and then towards folding means 22. If desired, initial zig-zag folds can be made by initial folding means 24, but this is not essential. Either the folding means 24 or the folding means 22 can comprise co operating folding plates (not shown) arranged to move relatively to one another so as to fold the filtering material between them.

Figure 2 shows the strips 14 on the filtering material prior to pleating, while Figure 3 shows the finally-pleated material. It will be noted that each strip 14 adheres to the filtering material over the full length of the strip.

If desired, each strip 14 can include a core of string, cord, wire or nylon which gives added strength to the filtering material finally obtained. The provision of such a core also makes it easier to produce filtering material with pleats having V-section gaps between them, the ribbons 14 being so stiffened by the cores of string, cord, wire or nylon to impart a rigidity to the pleated filtering material such that the pleats maintain the V-section gaps between them.

The precise dimensions glven above Ior the strips 14 are not to be taken as limiting the invention to them. Thus, the strips can be as narrow as 0.5 mm or as wide as 5 mm (where the filtering material is of large area). Likewise, the depth of the strips 14 can vary between 0.5 mm and 2 mm, according to the depth of the pleats and the spacing desired between them. Further, although the drawing and above description deals with the application of the strips 14 to one side only of the filtering material, they can equally well be applied to both sides.

WHAT I CLAIM IS: 1. Pleated filtering material for filtering air or other gaseous streams having pleatspacers in the form of spaced-apart strips, tapes or ribbons of a solid synthetic plastics material or of resin-impregnated paper or of aluminium foil each of which adheres over its full length to the filtering material itself by virtue of an adhesive applied to the pleat-spacer before it is brought into contact with the filtering material.

2. Pleated filtering material according to claim 1, in which the synthetic plastics material is a polyester or polyvinylchloride.

3. Pleated filtering material according to claim 1 or claim 2, in which the pleatspacers are between 0.5 mm and 5 mm wide.

4. Pleated filtering material according to any preceding claim, in which the strips are between 0.5 mm and 2 mm deep.

5. Pleated filtering material according to any preceding claim, in which adjacent folds of each pleat-spacer adhere to each other by virtue of adhesive previously applied to the spacer, thereby holding the pleats in the material as well as spacing the pleats therein.

6. Pleated filtering material according to any preceding claim, in which the filtering material itself comprises filter paper, glass fibre paper, open-pore polyurethane foam in sheet form, or a mat of random fibres.

7. Pleated filtering material according to any preceding claim, in which each strip, tape or ribbon includes a core of string, cord, wire or nylon to give added strength to the filtering material.

8. Pleated filtering material substantially as described herein with reference to the accompanying drawing.

9. A method of making pleated filtering material for filtering air or other gaseous streams which comprises applying spacedapart strips, tapes or ribbons of a synthetic plastics material or of resin-impregnated paper or of aluminium foil having an adhesive on them to one or both surfaces of the filtering material, and then folding or refolding the latter in zig-zag fashion to form pleats.

10. A method according to claim 9, in which the strips, tapes or ribbons are drawn from rolls.

11. A method according to claim 9, substantially as described herein with reference to the accompanying drawing.

12. Apparatus for carrying out the method of claim 9 substantially as described herein with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. operating folding plates (not shown) arranged to move relatively to one another so as to fold the filtering material between them. Figure 2 shows the strips 14 on the filtering material prior to pleating, while Figure 3 shows the finally-pleated material. It will be noted that each strip 14 adheres to the filtering material over the full length of the strip. If desired, each strip 14 can include a core of string, cord, wire or nylon which gives added strength to the filtering material finally obtained. The provision of such a core also makes it easier to produce filtering material with pleats having V-section gaps between them, the ribbons 14 being so stiffened by the cores of string, cord, wire or nylon to impart a rigidity to the pleated filtering material such that the pleats maintain the V-section gaps between them. The precise dimensions glven above Ior the strips 14 are not to be taken as limiting the invention to them. Thus, the strips can be as narrow as 0.5 mm or as wide as 5 mm (where the filtering material is of large area). Likewise, the depth of the strips 14 can vary between 0.5 mm and 2 mm, according to the depth of the pleats and the spacing desired between them. Further, although the drawing and above description deals with the application of the strips 14 to one side only of the filtering material, they can equally well be applied to both sides. WHAT I CLAIM IS:

1. Pleated filtering material for filtering air or other gaseous streams having pleatspacers in the form of spaced-apart strips, tapes or ribbons of a solid synthetic plastics material or of resin-impregnated paper or of aluminium foil each of which adheres over its full length to the filtering material itself by virtue of an adhesive applied to the pleat-spacer before it is brought into contact with the filtering material.