Air filter

• US 7,285,157 B1
• Filed: 07/26/2000
• Issued: 10/23/2007
• Est. Priority Date: 08/13/1999
• Status: Expired due to Fees

• Current Assignee: Arch UK Biocides Ltd. (Lonza Group AG)
• Original Assignee: Arch UK Biocides Ltd. (Lonza Group AG)
• Inventors: Dukes, Helen, Payne, John David
• Primary Examiner(s): Savage; Matthew
• Assistant Examiner(s): PHAM, MINH CHAU THI
• Application Number:
  US10/049,436
• Time in Patent Office: 2,645 Days
• Field of Search: 424/450, 424/488, 424/400, 424/76.21, 424/78.36, 424/78.37, 514/58, 514/937, 536/103, 536/101, 510/101, 502/404, 962/23
• US Class Current: 96/223
• CPC Class Codes: B01D 39/16 of organic material, e.g. synthetic fibres
• CPC Class Codes: B01D 39/18 the material being cellulose or derivatives thereof cork or peat B01D39/1646 ; making filter paper D21F11/14

Abstract

An air-filter for a circulating and/or recirculating air system using a filter medium containing a microbiologically effective amount of a polymeric biguanide or salt thereof. Also claimed is a method for reducing odors and/or air-borne micro-organisms in a circulating or recirculating air system using the air-filter, and a method for protecting an air-filter medium against microbial degradation by incorporating in, or on, the medium a microbiologically effective amount of a polymeric biguanide or salt thereof.

Claims

1. An air-filter for a circulating and/or recirculating air system comprising a filter medium containing a microbiologically effective amount of a polymeric biguanide or salt thereof, wherein said polymeric biguanide is terminated by a functional group selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, amine, and a cyanoguanidine group,

wherein said substituted hydrocarbyl is aryloxy, alkyloxy, acyl, acyloxy, or nitrile.

2. An air-filter as claimed in claim 1, wherein the polymeric biguanide contains at least two biguanide units of the Formula (1):

which are linked by a bridging group which contains at least one methylene group.

3. An air-filter as claimed in claim 1 wherein the polymeric biguanide is a mixture of linear polymeric biguanides having a recurring polymer chain represented by Formula (4):

wherein X and Y represent bridging groups in which together the total number of carbon atoms directly interposed between pairs of nitrogen atoms linked by X and Y is more than 9 and less than 17.

4. An air-filter as claimed in claim 3 which is a mixture of polymers wherein the number of individual biguanide units of formulae:

and

is, together, from 3 to about 80.

5. An air-filter as claimed in claim 3 wherein the polymeric biguanide is poly(hexamethylene biguanide) in which X and Y are both —

(CH₂)₆—

.

6. An air-filter as claimed in claim 1 wherein the polymeric biguanide is a mixture of polymers of the Formula (5):

wherein n is from 4 to 40.

7. An air-filter as claimed in claim 1 wherein the polymeric biguanide is in the form of a hydrochloride salt.

8. An air-filter as claimed in claim 1 wherein the filter medium is made from a natural polymer or synthetic plastics material.

9. An air-filter as claimed in claim 8 wherein the natural polymer is cellulose.

10. An air-filter as claimed in claim 1 wherein the amount of polymeric biguanide contained on the filter medium is from 0.0001% to 10% based on the weight of the filter medium.

11. A air-filter according to claim 1 further comprising an odour control agent.

12. A method of reducing odours and/or air-borne micro-organisms in circulating and/or recirculated air which comprises passing air through a filter medium containing a polymeric biguanide or salt thereof, wherein said polymeric biguanide is terminated by a functional group selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, amine, and a cyanoguanidine group,

wherein said substituted hydrocarbyl is aryloxy, alkyloxy, acyl, acyloxy, or nitrile.

13. A method as claimed in claim 12 wherein the air has a relative humidity between 20% and 80%.

14. A method for protecting a filter medium of a circulating and/or recirculating air system against microbial degradation which comprises incorporating in, or on, the medium a microbiologically effective amount of a polymeric biguanide or salt thereof, wherein said polymeric biguanide is terminated by a functional group selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, amine, and a cyanoguanidine group,

wherein said substituted hydrocarbyl is aryloxy, alkyloxy, acyl, acyloxy, or nitrile.