GB2077312A

GB2077312A - Pleated filtering material

Info

Publication number: GB2077312A
Application number: GB8016949A
Authority: GB
Original assignee: Marshall D A G
Current assignee: Marshall D A G
Priority date: 1980-05-22
Filing date: 1980-05-22
Publication date: 1981-12-16
Also published as: GB2077312B

Abstract

The pleats of pleated filtering material are held in place by lines, ribbons or blobs of synthetic plastics material which has been applied in a flowable form to one or both surfaces of the filtering material after the filtering material has been folded into pleats and then opened out again, and which is then hardened by infra-red heating whilst the filtering material is folded to reform the pleats. <IMAGE>

Description

SPECIFICATION Pleated filtering material This invention relates to pleated filtering material.

In my prior Patent No. 1,277,588 I have described a method of making pleated filtering material which comprises applying spaced-apart lines, ribbons or blobs of synthetic plastics material in liquid form to one or both surfaces of the filtering material, and then folding the latter in zig-zag fashion to form pleats, the said folding operation being effected while the said synthetic plastics lines, ribbons or blobs are still in their liquid state so that, after the synthetic plastics material has solidified, it holds or assists in holding the filtering material in its pleated form.

Further, in Patent No. 1,355,935 which was granted as a Patent of Addition to Patent No.

1,277,588, there is described a modified method of making such pleated filtering material which comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in liquid form to one or both surfaces of the filtering material, and thereafter causing the filtering material to fold up on itself in the same zig-zag fashion to form pleats while the said synthetic plastics lines, ribbons or blobs are still in their liquid state so that, after the synthetic plastics material has solidified, it holds or assists in holding the filtering material in its pleated form.

The present invention constitutes a development of the two methods described above.

According to the invention, a method of making pleated filtering material comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in a flowable form - for example, as a liquid or paste - to one or both surfaces of the filtering material and heating the synthetic plastics material by infra-red heating equipment to harden the latter very rapidly while folding the filtering material in zig-zag fashion to reform the pleats which are then held in placed by the hardened synthetic plastics material.

Preferably, the synthetic plastics material used is polyvinylchloride (PVC) which is brought into a molten form prior to its being applied to the filtering material. The invention also extends to apparatus for carrying out the said method and to pleated filtering material when made by that method and apparatus.

A specific example of a method and apparatus for making pleated filtering material in accordance with the invention is shown in the accompanying drawings, in which Figure 1 shows the apparatus for making the material, in a diagrammatic form; and Figure 2 is a perspective view of the finallyproduced filtering material.

The apparatus shown in Figure 1 comprises a roll 10 of filtering material in sheet form. This can, for example, be filter paper, glass fibre paper, open-pore polyurethane foam material, random fibre mat, or some other filtering material which is available in sheet form.

The filtering material is drawn off the roll 10 by means not shown in the drawing into or past initial folding means 12 which fold the material in zigzag fashion. The material is then opened out again to form a reasonably flat surface as shown at 14, whereupon it passes under and above, respectively, two transverse lines of nozzles 1 6 and 1 8 which extend across the full width of the filtering material. The delivery openings 20 and 22 of the nozzles 1 6 and 1 8 are located between 1 mm and 5 mm from the surface of the filtering material. Assuming that the filtering material has a width of, say, 0.5 of a metre, the nozzle openings 20, 22 can be between 2 cm and 5 cm apart.Each nozzle 1 6, 1 8 is supplied with molten PVC or some other synthetic plastics material of low melting point from a pressure container (not shown) having heating means to melt the plastics material.

Immediately after the sheet filtering material has moved past the nozzles 18, it is subjected to infra-red heating from infra-red heating apparatus 24. This heating hardens the PVC very rapidly.

While this hardening is taking place the filtering material is refolded in zig-zag fashion to reform the pleats originally formed in it at the initial folding station 12. By the time the pleats are reformed the PVC has already hardened to a tacky state. The ribbons or lines of PVC on adjacent pleats therefore adhere to each other, and in this way the pleats are held in place very firmly once the PVC has thoroughly hardened. The thusproduced pleated filtering material will then have the form illustrated in Figure 2 of the drawing.

Variations can be made in the apparatus described above. For example, provision can be made for each line or ribbon of molten PVC to have a core of string, cord, wire or nylon which gives added strength to the filtering material finally obtained.

As compared with the methods described in my prior British Patents Nos. 1,277,588 and 1,355,935, the method of the present invention has the advantage that the molten synthetic plastics lines or ribbons solidify or harden very much more rapidly than in those prior methods.

In orther words, the provision of infra-red heating apparatus to accelerate hardening of the synthetic plastics lines or ribbons brings a special benefit in that the filtering material can be refolded to reform the pleats amost immediately after the filtering material has passed by the nozzles 1 6 and 1 8.

1. A method of making pleated filtering material which comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in a flowable form to one or both surfaces of the filtering material, and heating the synthetic plastics material by infrared heat to harden the synthetic

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Pleated filtering material This invention relates to pleated filtering material. In my prior Patent No. 1,277,588 I have described a method of making pleated filtering material which comprises applying spaced-apart lines, ribbons or blobs of synthetic plastics material in liquid form to one or both surfaces of the filtering material, and then folding the latter in zig-zag fashion to form pleats, the said folding operation being effected while the said synthetic plastics lines, ribbons or blobs are still in their liquid state so that, after the synthetic plastics material has solidified, it holds or assists in holding the filtering material in its pleated form. Further, in Patent No. 1,355,935 which was granted as a Patent of Addition to Patent No. 1,277,588, there is described a modified method of making such pleated filtering material which comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in liquid form to one or both surfaces of the filtering material, and thereafter causing the filtering material to fold up on itself in the same zig-zag fashion to form pleats while the said synthetic plastics lines, ribbons or blobs are still in their liquid state so that, after the synthetic plastics material has solidified, it holds or assists in holding the filtering material in its pleated form. The present invention constitutes a development of the two methods described above. According to the invention, a method of making pleated filtering material comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in a flowable form - for example, as a liquid or paste - to one or both surfaces of the filtering material and heating the synthetic plastics material by infra-red heating equipment to harden the latter very rapidly while folding the filtering material in zig-zag fashion to reform the pleats which are then held in placed by the hardened synthetic plastics material. Preferably, the synthetic plastics material used is polyvinylchloride (PVC) which is brought into a molten form prior to its being applied to the filtering material. The invention also extends to apparatus for carrying out the said method and to pleated filtering material when made by that method and apparatus. A specific example of a method and apparatus for making pleated filtering material in accordance with the invention is shown in the accompanying drawings, in which Figure 1 shows the apparatus for making the material, in a diagrammatic form; and Figure 2 is a perspective view of the finallyproduced filtering material. The apparatus shown in Figure 1 comprises a roll 10 of filtering material in sheet form. This can, for example, be filter paper, glass fibre paper, open-pore polyurethane foam material, random fibre mat, or some other filtering material which is available in sheet form. The filtering material is drawn off the roll 10 by means not shown in the drawing into or past initial folding means 12 which fold the material in zigzag fashion. The material is then opened out again to form a reasonably flat surface as shown at 14, whereupon it passes under and above, respectively, two transverse lines of nozzles 1 6 and 1 8 which extend across the full width of the filtering material. The delivery openings 20 and 22 of the nozzles 1 6 and 1 8 are located between 1 mm and 5 mm from the surface of the filtering material. Assuming that the filtering material has a width of, say, 0.5 of a metre, the nozzle openings 20, 22 can be between 2 cm and 5 cm apart.Each nozzle 1 6, 1 8 is supplied with molten PVC or some other synthetic plastics material of low melting point from a pressure container (not shown) having heating means to melt the plastics material. Immediately after the sheet filtering material has moved past the nozzles 18, it is subjected to infra-red heating from infra-red heating apparatus 24. This heating hardens the PVC very rapidly. While this hardening is taking place the filtering material is refolded in zig-zag fashion to reform the pleats originally formed in it at the initial folding station 12. By the time the pleats are reformed the PVC has already hardened to a tacky state. The ribbons or lines of PVC on adjacent pleats therefore adhere to each other, and in this way the pleats are held in place very firmly once the PVC has thoroughly hardened. The thusproduced pleated filtering material will then have the form illustrated in Figure 2 of the drawing. Variations can be made in the apparatus described above. For example, provision can be made for each line or ribbon of molten PVC to have a core of string, cord, wire or nylon which gives added strength to the filtering material finally obtained. As compared with the methods described in my prior British Patents Nos. 1,277,588 and 1,355,935, the method of the present invention has the advantage that the molten synthetic plastics lines or ribbons solidify or harden very much more rapidly than in those prior methods. In orther words, the provision of infra-red heating apparatus to accelerate hardening of the synthetic plastics lines or ribbons brings a special benefit in that the filtering material can be refolded to reform the pleats amost immediately after the filtering material has passed by the nozzles 1 6 and 1 8. CLAIMS

1. A method of making pleated filtering material which comprises folding the filtering material in zig-zag fashion and then opening it out again, applying spaced-apart lines, ribbons or blobs of synthetic plastics material in a flowable form to one or both surfaces of the filtering material, and heating the synthetic plastics material by infrared heat to harden the synthetic plastics material while folding the filtering material in zig-zag fashion to reform the pleats which are then held in place by the hardened synthetic plastics material.

2. A method according to claim 1, in which the synthetic plastics material is applied in the form of a liquid or paste.

3. A method according to claim 1 or claim 2, in which the synthetic plastics material is polyvinylchloride (PVC) which is brought into a molten form prior to its being applied to the filtering material.

4. Pleated filtering material when made by a method according to any one of claims 1-3.

5. Pleated filtering material having pleats which are held in place by a synthetic plastics material hardened as a result of being subjected to infrared heat.

6. Pleated filtering material according to claim 4 or claim 5, in which the filtering material comprises filter paper, glass fibre paper, open-pore polyurethane foam material or random fibre mat.

7. Pleated filtering material according to any one of claims 21- 6, in which each line, ribbon or blob of synthetic plastics material has an internal core of string, cord, wire or nylon to give added strength to the filtering material.

8. Pleated filtering material according to any one of claims 4-7 substantially as described herein with reference to Figure 2 of the accompanying drawing.

9. Appparatus for making filtering material as claimed in any one of claims 4-8, comprising means for drawing or directing filtering material in sheet form into or past initial folding means to fold the material in zig-zag fashion while permitting the material to bethen opened out again to form a reasonably flat surface, two transverse lines of nozzles extending across the fuli width of the filtering material to apply molten PVC or other synthetic plastics material of low melting point to both surfaces of the filtering material, infrared heating apparatus to harden the PVC thus applied, and means for refolding the filtering material in zig-zag fashion to reform the pleats originally formed in it by the initial folding means.

1 0. Apparatus according to claim 9 substantially as described herein with reference to Figure 1 of the accompanying drawing.