HK1018010A - Method of disinfecting the air - Google Patents

Description

Method for sterilizing air

The present invention relates to a method of disinfecting air and killing airborne bacteria using a heated wick to produce particles of a disinfecting compound. The invention is particularly concerned with a method of producing particles of compounds which are known to kill airborne bacteria when dispersed in air in the form of small particles which are produced indirectly by heating a wick at or near the top.

Indirect heating has long been known as a method of producing fumigant compounds of pesticide materials. Examples of such compositions and methods are disclosed in U.S. patent 4,745,705. This patent discloses a method of delivering an insecticide by means of a porous absorbent wick by immersing the wick in an insecticide solution and indirectly heating it at the top to evaporate the absorbed solution to the atmosphere. This patent does not disclose that the insecticide is dispersed in the air as particles.

There are also numerous patents disclosing porous cores as a means of delivering insecticides. These patents include: US5095647, US4663315, US5038394 and US 5290546. None of these patents disclose that these devices can be used to generate air sanitizer particles.

It is known that certain glycol compounds may also provide some air cleaning when sprayed into the air. It has been found that effective amounts of these materials are typically about 5% or more active glycol (US EPA document 9/3 1980).

The invention relates to a method for disinfecting air, comprising: immersing a portion of a porous wick in the liquid sanitizing composition and indirectly heating the top of the wick to produce particles of said active sanitizing agent into the air, wherein at least 90% of the produced particles have a particle size no greater than 10 microns.

The attached drawing is a schematic diagram of the device used in the method of the invention.

As indicated above, it is known that certain air disinfectants or air cleaners must be present in the air in some form in order to make them active. The applicant believes that the medicament must be active in the form of particles and/or by attaching itself to particles already in the air, such as dust particles. Thus any such air sanitizer or cleaner that can be formulated in a particular form by a heated core generator can be used in the method of the present invention. However, it is preferred to use certain glycol compounds when these materials can rapidly generate particles that form aerosol suspensions in air at temperatures at which small consumer appliances are safe to use. Preferred glycol materials are propylene glycol, dipropylene glycol, triethylene glycol, and mixtures thereof. The most preferred compound of these glycol materials is dipropylene glycol.

Since many air cleaning active materials are water soluble, the diluent used in the process of the present invention is most preferably water. Other diluents, solvents and co-solvents may also be used, however, it is believed that highly volatile hydrocarbon solvents reduce the efficacy of the process of the invention and should in principle be avoided. In addition, other volatile materials such as perfumes should also be avoided or applied in small amounts, typically less than 15% of the total formulation. The formulation used in the process of the invention is preferably substantially free of perfume.

The specific concentration of active material in the concentrate contained in the package suitable for use in the method of the present invention may vary from as low as 5% to as high as 100% active material. Small amounts of fragrances or perfumes may also be included in this regard without adversely affecting the air cleaning action of the active ingredient. In contrast, the diluent is present in an amount that varies with the amount of active material from 0% at 100% active material to about 95% at about 5% active material. Preferred diluent materials are solvents for the active material. For glycols, the preferred diluent is water.

Turning now to the schematic illustration of the present invention, the present invention comprises an enclosure or housing 10 including an opening 20 in a top surface thereof. Located around the opening 20 is a heating element 30. This element may be any conventional heating element such as a ring heater, a wire wound heater or one or more PTC (positive temperature coefficient) heaters. The particular type of heating element is not critical to the present invention. So long as the heating element is capable of heating the top of the wick 40 to a temperature in the range of about 50-120 c. Heating element 30 is connected by conductor 70 to a source of electrical power, which may be a battery pack or a household outlet.

The core 40 may be made of any conventional material for such cores. Suitable materials include porous ceramic cores and the like. Suitable core materials are disclosed in US4663315, the disclosure of which is incorporated by reference. Preferred core materials are ceramics, polyester, compressed wood, sintered polypropylene and polyethylene, and carbon fibers.

The core 40 is placed at the opening of the case 50. It is preferable that the wick 40 is disposed at the opening of the case 50 in a sealed form so that the liquid air cleaning material 60 in the case 50 cannot be easily discharged. The manner in which the core 40 is sealed at the opening of the tank 50 is conventional and does not form part of the present invention.

Surprisingly, the evaporation device of the above-described type produces air cleaning agent particles in a range where one of these known cleaning agent materials is active. It has been observed that more than 90% of the particles produced by the above-described apparatus have a particle size in the range of about 0.16-5 microns. Air cleaner materials are very effective in this particle size range.

The process of the present invention will now be demonstrated by the following examples, which are for purposes of illustration only and not by way of limitation.

Example 1

The following formulation was prepared:

weight percent of the component

Dipropylene glycol 90

Fragrance (TBA73299) 10

45g of the above formulation was placed in a bottle with a ceramic core having an average pore size of 0.7 μm. This bottle and wick combination was then placed in an electric heating device to heat the top of the wick to a temperature of about 100 ℃. The device was placed in a room with temperature and humidity controlled at 22 ℃ and 40% RH. The room was equipped with a Met One # 200 clean room particle counter and Mattson-Garvin 220 slit against an agar knock-out probe to determine the number of bacterial colonies over a period of time. After about 24 hours, an airborne bacterium, Micrococcus luteus lysodiekticus, was introduced into the room. The total particle count and relative size of the particles were determined. The decrease in the number of bacterial colonies over this period was also determined. A control room without any particle generating device also showed a decrease in the number of bacterial colonies. The above device produced 6.39 million particles after a 24 hour period. The weight loss of the formulation in the bottle was 1.67g over the above time. In the following table, 10-15 refers to 10-15 minutes from the introduction of the bacteria into the room. The bacterial population numbers were as follows:

0-5 10-15 20-25 30-35 40-45 50-55

example 1100000

Comparative example 2931831461137744

It is clear that the present method reduces the number of airborne bacteria after only a short time.

Example 2:

the procedure of example 1 was repeated except that the following formulation was used:

weight percent of the component

Triethylene glycol 10

Deionized water 90

The number of particles produced over 24 hours was 3.1 million, and the weight loss was 0.98 g. The following results were observed.

0-5 10-15 20-25 30-35 40-45 50-55

Example 228105524

Comparative example 32225616113411077

There is still a significant reduction in the number of airborne bacteria present.

The method of the present invention is used to reduce the number of airborne bacteria present in an indoor environment. Since certain bacteria are known to cause disease, the use of the methods of the present invention can minimize the transmission of certain infectious diseases.

Claims (10)

1. A method of sanitizing air comprising indirectly heating a porous wick, the wick having a top portion located adjacent a heat source and a bottom portion immersed in a liquid sanitizing composition such that the top portion of the wick has a sufficient temperature to produce particles of said sanitizing composition, and then dispersing the particles in air, wherein at least 90% of the produced particles have a particle size of no more than 5 microns.

2. The method of claim 1, wherein the core is heated to a temperature in the range of about 50-120 ℃.

3. The method of claim 1 wherein the liquid disinfecting composition comprises a glycol as the active disinfectant.

4. The process of claim 3 wherein the diol is selected from the group consisting of: propylene glycol, dipropylene glycol, triethylene glycol, and mixtures thereof.

5. The method of claim 3 wherein the liquid sanitizing composition comprises water as a diluent.

6. The method of claim 3 wherein the liquid disinfecting composition comprises from about 5 to 100% glycol and from about 95 to 0% water.

7. The method of claim 6 wherein the diol is dipropylene glycol.

8. The method of claim 7 wherein the liquid disinfecting composition comprises from about 10% to about 100% dipropylene glycol and from about 0% to about 90% water.

9. The method of claim 3, wherein the composition further comprises less than 15% perfume.

10. The method of claim 3, wherein the composition is substantially free of perfume.