Fl ELD OF THE I NVENTI ON

This invention relates to volatile dispensing devices that employ active means to dispense volatiles from a volatile-impregnated substrate.

BACKGROUND

Devices for dispensing thermally or otherwise volatilizable materials into the atmosphere are well known. Such volatilizable materials may be air scents (e.g., fragrances), pest control materials (e.g., insecticides), allergen control ingredients, disinfectants, and the like.

In one type of volatile material dispensing device, a heat source is used to promote the wicking action and release of a volatile material from a wick, one end of which is immersed in a volatile liquid contained in a reservoir. One version of this type of device is plugged into an electrical wall outlet to supply power to a heating coil within a housing. The generated heat raises the temperature of a material contained in the wick and volatilizes the material. Convection air currents dispense the volatilized material into the room. Examples of this type of device and related devices can be found in U.S. Patent Nos. 6,361,752; 5,647,053; 5,290,546; 5,222,186; 5,095,647; 5,038,394; and 4,663,315; and European Patent No EP 1 825 748. The disclosure of these patents and all other publications referred to herein are incorporated herein by reference as if fully set forth.

In another type of volatile material dispensing device, a stiff, porous mat (commonly made of a pressed, cellulosic, fibrous material) is impregnated with a volatile material, or a volatile material is placed in a pan-like metal structure. These mats and pans are then placed on heaters to cause the volatile material to vaporize into the atmosphere. Examples of this type of device and related devices can be found in U.S. Patent Nos. 6,446,384; 6,309,986; 6,031,967; 5,945,094; and 4,391,781.

In yet another type of volatile material dispensing device, a stiff, porous mat is impregnated with a volatile material, and the mat is held within the device such that a flow of hot gases from a fuel burner passes over the mat and causes the volatile material to vaporize into the atmosphere. An example of this type of device can be found in PCT International Patent Publication No. WO 00/78835. In yet another type of volatile material dispensing device, moving air is directed against a substrate or through a reticulated or otherwise airflow-transmitting substrate to thereby volatilize volatile material with the substrate has been impregnated. Examples of this type of device can be found in U.S. Patent No. 5,547,616 and in PCT International Patent Publication No. WO 01/02025.

While all of these devices provide satisfactory results under certain circumstances, there are drawbacks to each type of device.

In devices that use a heat source to promote the release of a volatile material from a wick immersed in a volatile liquid composed of solvents and dissolved active ingredients, presently available wicking materials limit the performance of the wick of the device. For instance, when using porous wicks made of felt or fabric in such a device, there is a tendency as the wick is heated for the solvents to quickly volatilize off, thereby leaving high boiling point materials behind in the wick. The high boiling point materials remaining in the wick can cause clogging of the wick. Other wick materials include ceramics and compressed sawdust. However, these wicks experience the same sort of clogging when used in a device that uses a heat source to promote the release of a volatile material from a wick immersed in a volatile liquid. As a result, it is difficult to maintain stable evaporation of the volatile liquid for extended time periods. While uniform release of volatiles has been reported in U.S. Patent Nos. 4,286,754 for non-heated wicks, the problem of non-linear release in heated wicks remains.

Certain volatile materials, such as some insecticide formulations, include materials that either are or become non-volatile when the liquid is heated in a wick. These non-volatile materials can cause clogging of the wick, which leads to a less uniform release rate of the volatile during use over time and to high residual levels of nonvolatile materials in an expended wick. For example, pyrethrum insecticides typically include or form non-volatile waxes or polymers. During use in a dispenser having a conventional ceramic or sawdust wick, these waxes form sludges that can clog the wick. Thus, ceramic and sawdust wick systems do not allow effective utilization of insecticidal formulas that contain natural pyrethrins and terpenes.

One proposed solution to the problems associated with the clogging of wicks by nonvolatiles formed by oxidation of pyrethrum insecticides has been the use of antioxidants in the liquid formulation. See, for example, U.S. Patent No. 4,968,487 which utilizes in particular BHT and BHA. However, in spite of antioxidants, some cross-linking of the isoprene units in insecticidal liquid formulations occurs, forming non-volatile components that degrade the wicking performance of traditional wicks. The performance losses in these systems can be attributed to clogging of the small pores and the effects of the high tortuosity (twists and turns) in conventional wick materials.

Thus, there is a need for an improved liquid-delivery wick that can be used in a dispensing device that uses a heat source or other active means to promote the release of a volatile material from the wick. In particular, there is a need for wicks that provide improved efficacy (including but not limited to non-clogging, linear, and complete volatile release) and low cost, together with compatibility with existing dispensing devices.

SUMMARY OF THE I NVENTI ON

The present invention and embodiments thereof serve to provide a solution to one or more of above-mentioned disadvantages. To this end, the present invention relates to a dispensing device according to claim 1

Preferred embodiments of the device are shown in any of the claims 2 to 7.

A specific preferred embodiment relates to an invention according to claim 3. The combination pyrethrins and carnosic acid has shown a linear evaporation rate throughout the wicks lifetime. Additionally, both pyrethrins and carnosic acid can be naturally sourced. This is advantageous over synthetic derivates of (natural) pyrethrum. It is also desired by an increasing amount of consumers who prefer "green" or naturally sourced alternatives; due to concerns with respect to ecological impact as well as safety.

In a second aspect, the present invention relates to kit according to claim 8.

In a third aspect, the present invention relates to a reservoir according to claim 12. In a fourth aspect, the present invention relates to a method for delivering a volatile material according to claim 14. The inventors found that the evaporation rate remained surprisingly constant throughout the lifetime of the wick compared to the prior art.

The invention further relates to a method wherein the dispensing device is activated less frequently according to claim 11. The inventors surprisingly found that the volatiles were dispensed at an insect controlling rate, even when the heating device was only activated 9 hours a day. In the prior art, generally heating devices are activated 12 hours a day. Without being bound by theory, it is believed the dispensing devices according to the prior art utilize longer heating times to ensure volatiles are dispensed at an insect controlling rate when the wick has significant buildup of solid residue.

In order to guarantee volatiles are dispensed at an insect controlling rate, even when the evaporation rate reduces, dispensing devices according to the prior art are activated longer or more intensively. With a more constant evaporation rate, the activation time, without an increase in intensity, while guaranteeing volatilization at an insect controlling rate. This in turn also increases the lifetime of the wick, as clogging typically occurs when the heater is activated.

DESCRI PTI ON OF Fl GURES

The following description of the figures of specific embodiments of the invention is merely exemplary in nature and is not intended to limit the present teachings, their application or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Figure 1 A is a perspective view showing a device for dispensing volatile materials from a wick and embodying the invention.

Figure 1 B is a side cross-sectional view of the device of Figure 1A.

Figure 2A is a perspective view showing another device for dispensing volatile materials from a wick and embodying to the invention.

Figure 2 B is a side cross-sectional view of the device of Figure 2A.

Figure 3A shows a wick after 396 hours of heating with a liquid volatile material according to the present invention.

Figure 3 B shows a wick after 350 hours of heating with a liquid volatile material according to the prior art.

DETAI LED DESCRI PTI ON OF THE I NVENTI ON

The present invention concerns a dispensing device, a kit suitable for constructing said dispensing device, a reservoir suitable for such a dispensing device and a method for delivering a volatile material. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

As used herein, the following terms have the following meanings:

"A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

"About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/- 20% or less, preferably +/-10% or less, more preferably +/-5% or less, even more preferably +/-1% or less, and still more preferably +/-0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

"Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g., component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints. The expression "% by weight", "weight percent", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the invention.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

An "effective amount" or an "effective delivery rate" and the like term is defined to mean that amount or rate sufficient to achieve the intended effect. "Active means" is defined as heat, moving air, or other means of imparting energy to a volatile material to be dispensed, and a volatile dispensing device that employs active means to dispense volatiles will be referred to as "actively dispensing" the volatile material. To be effective, insect control volatile active ingredients have to be delivered at no less than an "insect controlling rate," defined herein as that rate sufficient to repel or otherwise control target insects within the space to be protected.

In a first aspect, the invention provides a dispensing device including a reservoir (28); a liquid volatile material (34) in a reservoir (28); a heater (25); a wick (31) designed to deliver the volatile material (34) from the reservoir (28) to a heated location within the heater (25) to promote release of vaporized volatile material from the wick (31); wherein the volatile material (34) in the reservoir comprises an insect control active ingredient; and the wick (31) comprises a substrate of particles or fibers adhered together to form a body having a network of pores and passages, the interior surfaces of which are non-reactive and non-absorptive with respect to the volatile material (34) to be dispensed, the body being formed to occupy the heated location within the heater (25), wherein activation of the volatile dispensing device releases the volatile material from the pores, which volatile material is then dispensed when the heater (25) is activated wherein said liquid volatile material comprises carnosol, carnosic acid, a salt thereof or a mixture thereof.

The inventors found that the addition of carnosol, carnosic acid, a salt thereof or a mixture thereof significantly reduced the solid residue buildup within the wick. The aged wick looks clean and keeps the same diameter even after 45 days of use.

When solid residue builds up within a wick, the wick's diameter increases. This leads to difficulties when removing the wick from the heating device and I or the reservoir which are usually tight-fit. Increasing the tolerance between the wick and the reservoir and I or heating device is not desirable due to increased, uncontrolled vaporization of the volatiles related to convection. Additionally, solid residue buildup tends to exacerbate the buildup of material stress within the wick; causing the wick to be more brittle.

By reducing the buildup of solid residue within the wick, the wick does not thicken nor brittle and can easily be removed from both the heating device and the reservoir. This makes reuse of the heating device significantly easier and pleasant for the consumer. New wicks and reservoirs containing volatile material may be provided and attached to a reusable heating device. In a more preferred embodiment, wicks may also be reused and attached to a new reservoir containing fresh volatile material. In a preferred embodiment, the sum of the concentration of carnosol, carnosic acid and salts thereof is between 0.001 and 0.1 wt.% relative to the liquid volatile material. The inventors have found that this range of concentrations is sufficient to prevent solid residue buildup within the wick.

In a preferred embodiment, the insect control material is pyrethrins, more preferably natural pyrethrins. "Natural" pyrethrins as described herein are sourced from plants, preferably flowers. The term "pyrethroids" refers to insecticides related to pyrethrins which are not found in nature and can only be produced synthetically.

In a preferred embodiment, carnosol, carnosic acid, a salt thereof or a mixture thereof is derived from rosemary extract. Rosemary as described herein refers to Rosmarinus officinalis.

In a particularly advantageous embodiment, both pyrethrins and carnosol, carnosic acid, a salt thereof or a mixture thereof are naturally sourced. These "green" alternatives are ecologically desirable and are generally perceived as desirable by customers and consumers. In a preferred embodiment, the rosemary extract is odorless. The dispensing device of the present invention is aimed at providing an insecticide activity; not to provide a desirable fragrance. Some consumers prefer the dispensing device to function odorless.

In a preferred embodiment, the liquid volatile material comprises pyrethrins, preferably natural pyrethrins, in an amount of at least 0.1 wt.% relative to the liquid volatile material, preferably in an amount of at least 0.5 wt.%, more preferably in an amount of at least 1.0 wt.%, more preferably in an amount of at least 2.0 wt.%, more preferably in an amount of at least 2.5 wt.%, more preferably in an amount of at least 3.0 wt.%, more preferably in an amount of at least 3.5 wt.%, more preferably in an amount of at least 4.0 wt.%, more preferably in an amount of at least 4.5 wt.%, most preferably in an amount of about 5.0 wt.%. In a preferred embodiment, the liquid volatile material comprises pyrethrins, preferably natural pyrethrins, in an amount of at most 25 wt.% relative to the weight of the liquid volatile material, more preferably in an amount of at most 20 wt.%, more preferably in an amount of at most 15 wt.%, more preferably in an amount of at most 14 wt.%, more preferably in an amount of at most 13 wt.%, more preferably in an amount of at most 12 wt.%, more preferably in an amount of at most 11 wt.%, more preferably in an amount of at most 10 wt.%, more preferably in an amount of at most 9 wt.%, more preferably in an amount of at most 8 wt.%, more preferably in an amount of at most 7.5 wt.%, more preferably in an amount of at most 7.0 wt.%, more preferably in an amount of at most 6.5 wt.%, more preferably in an amount of at most 6.0 wt.%, more preferably in an amount of at most 5.5 wt.%, more preferably in an amount of about 5.0 wt.%. In a preferred embodiment, the liquid volatile material comprises pyrethrins, preferably natural pyrethrins, in an amount of 1.0 to 15.0 wt.% relative to the weight of the volatile material, more preferably in an amount of 1.0 to 10.0 wt.%, more preferably in an amount of 2.0 to 8.0 wt.%, more preferably in an amount of 2.5 to 7.5 wt.%, more preferably in an amount of 3.0 to 7.0 wt.%.

In a further preferred embodiment, the liquid volatile material comprises 1.0 to 10.0 wt.% rosemary extract, preferably the liquid volatile material comprises 1.5 to 9.5 wt.% rosemary extract, preferably the liquid volatile material comprises 2.0 to 9.0 wt.% rosemary extract, preferably the liquid volatile material comprises 2.5 to 8.5 wt.% rosemary extract, preferably the liquid volatile material comprises 3.0 to 8.0 wt.% rosemary extract, preferably the liquid volatile material comprises 4.0 to 8.0 wt.% rosemary extract, preferably the liquid volatile material comprises 5.0 to 8.0 wt.% rosemary extract, most preferably the liquid volatile material comprises 5.5 to

7.5 wt.% rosemary extract.

In a preferred embodiment, the ratio of rosemary extract to pyrethrins, preferably natural pyrethrins, in the volatile liquid material is at least 1: 100, preferably at least 1 :50, more preferably at least 1 :40, more preferably at least 1:30, more preferably at least 1 :20, more preferably at least 1: 15, most preferably about 1 : 10. In a preferred embodiment, the ratio of rosemary extract to pyrethrins, preferably natural pyrethrins, in the volatile liquid material is at most 5: 1, more preferably at most 1: 1, more preferably at most 1:2, more preferably at most 1 :4, more preferably at most 1:5, more preferably at most 1 :8, most preferably about 1 : 10. In a preferred embodiment, the ratio of rosemary extract to pyrethrins, preferably natural pyrethrins, in the volatile liquid material lies between 50: 1 and 1 : 1, preferably between 20: 1 and 2: 1, most preferably between 20: 1 and 5: 1.

In a preferred embodiment the liquid volatile material comprises a solvent. Solvents improve the evaporation rate of the pyrethrins. Preferably, said solvents promote a stable, constant evaporation of the liquid volatile material. It is clear that the solvents need to be physiologically acceptable, i.e., not irritating, harmful to health of mammals particularly humans, non-corrosive and odorless. In a preferred embodiment, the solvent comprises C6 to C20 hydrocarbons. More preferably, the solvent comprises predominantly linear and branched alkanes with a low aromatics content. More preferably, the solvent comprises predominantly or entirely branched alkanes. In a further preferred embodiment, the solvent comprises at least one C8 to C14 linear or branched alkane, most preferably isododecane. In another preferred embodiment, the solvent may be a petroleum distillate. Preferably said petroleum distillate is hydrotreated. Hydrotreated petroleum distillates have a lower content of unsaturated and aromatic hydrocarbons as well as nitrogen and sulphur compounds. Avoiding or reducing the amount of these compounds is desired. More preferably, the solvent comprises a hydrotreated petroleum middle distillate, comprising predominantly (i.e., at least 90 wt.%) C14 to C19 hydrocarbons. In a preferred embodiment, the sum of linear and branched, C6 to C20 alkanes in the liquid volatile material is an amount of at least 30 wt.%, preferably at least 50 wt.%, more preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, more preferably at least 85 wt.%, more preferably at least 90 wt.%.

In a preferred embodiment, the sum of hydrotreated petroleum middle distillate and isododecane are comprised in the liquid volatile material in an amount of at least 30 wt.% relative to the liquid volatile material, preferably at least 50 wt.%, more preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, more preferably at least 85 wt.%, more preferably at least 90 wt.%.

In a preferred embodiment the liquid volatile material comprises a hydrotreated petroleum middle distillate (CAS no. 64742-46-7) and isododecane (CAS no. 13475- 82-6). The inventors surprisingly found that such a mixture provides for a stable, linear evaporation rate with sufficient evaporation to effectively repel mosquitos. In a preferred embodiment, the hydrotreated petroleum middle distillate preferably comprises C14 to C19 hydrocarbons, isoalkanes, cyclics and less than 2 wt.% aromatics. In a further preferred embodiment, the liquid volatile material comprises a hydrotreated petroleum middle distillate and isododecane in a ratio by weight of at least 50/50, more preferably at least 70/30, more preferably at least 75/25, more preferably at least 80/20, more preferably at least 85/15, more preferably at least 90/10. In another preferred embodiment, the liquid volatile material comprises a hydrotreated petroleum middle distillate and isododecane in a ratio by weight of at most 99/1, more preferably at most 97/3, more preferably at most 95/5, more preferably at most 93/7, more preferably at most 90/10. In another embodiment, the liquid volatile material comprises a hydrotreated petroleum middle distillate and isododecane in a ratio between 70/30 and 99/1, more preferably in a ratio between 75/25 and 97/3, more preferably in a ratio between 80/20 and 95/5, more preferably in a ratio between 85/15 and 93/7, most preferably in a ratio of about 90/10. In a preferred embodiment, the total amount of hydrotreated petroleum middle distillate and isododecane in the liquid volatile material at least 30 wt.% relative to the liquid volatile material, preferably at least 50 wt.%, more preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, more preferably at least 85 wt.%, more preferably at least 90 wt.%.

In a preferred embodiment, the wick comprises bonded polymer fibers. Suitable polymers can be chosen from the list of polyolefins, particularly polyethylene and polypropylene, PVC, polyamides, and polyesters particularly PET and PBT. Preferably said bonded polymer fibers are twisted, producing a high tortuosity which produces a multitude of small pores. In a preferred embodiment, the wick comprises bonded nylon fibers. Nylon fibers refers to polyamide 6 or polyamide 6,6 fibers.

In the second aspect, the invention relates to a kit comprising:

- a dispensing device comprising a heater,

- a wick, comprising a substrate of particles or fibers adhered together to form a body having a network of pores and passages, and

- a reservoir comprising a liquid volatile material, said liquid volatile material comprising carnosol, carnosic acid, a salt thereof or a mixture thereof and an insect control active ingredient.

The kit according to the second aspect can advantageously be assembled to a dispensing device according to the first aspect of the invention.

Additionally, as the present invention relates to a composition which drastically reduces the buildup of solid residue and clogging within the wick; the wick may be reused. In particular, a new reservoir can be provided, or the reservoir can be refilled with liquid volatile material.

In a preferred embodiment, the reservoir is a disposable refill reservoir. Preferably said disposable refill reservoir is provided with a seal which is removed prior to assembling the disposable refill reservoir with the wick and dispensing device comprising the heater.

In a preferred embodiment of the kit, the wick is attached to the dispensing device. In another embodiment of the kit, the wick is attached to the reservoir. In both of these preferred embodiments, the wick is pre-assembled in relation to either the dispensing device or the reservoir. This reduces the number of steps and parts required for assembly by the consumer; improving safety and reducing the chance of erroneous assembly.

In a third aspect, the invention relates to a reservoir suitable for a dispensing device, comprising a liquid volatile material, said liquid volatile material comprising carnosol, carnosic acid, a salt thereof or a mixture thereof and an insect control active ingredient. The reservoir according to the third aspect is suitable for use in combination with a dispensing device according to the first aspect and a kit according to the second aspect. It may advantageously be used to refill the dispending device. In one embodiment, the reservoir includes a wick. In another embodiment, the original wick can be re-used and only a reservoir comprising liquid volatile material is included. Preferably the reservoir is sealed with a removable seal, such as a pierceable seal.

It is clear that the preferred embodiments herein described for the first aspect of the invention also apply to the other aspects of the invention. In particular all preferences related to the liquid volatile material with respect to the dispensing device of the first aspect, apply mutatis mutandis to the kit of the second aspect and the reservoir of the third aspect of the invention.

In a fourth aspect, the invention relates to a method for delivering a volatile material from a dispensing device that uses a heater (25) to promote release of vaporized volatile materials (34) from a wick (31) designed to deliver a volatile material (34) from a reservoir (28) to a heated location within a heater (25) wherein the volatile material (34) can be heated and volatilized, the method comprising the steps of:

- providing as the volatile material a liquid in the reservoir containing an insect control active ingredient;

- providing as a wick (31) a substrate comprising granular particles adhered together to form a body having a network of pores and passages, the interior surfaces of which are non-reactive and non-absorptive with respect to the volatile material to be dispensed, the body being formed to occupy the heated location within the heater, wherein activation of the volatile dispensing device releases the volatile material from the pores, which volatile material is then dispensed; and

- activating the heater (25); wherein the liquid in the reservoir further contains carnosol, carnosic acid, a salt thereof or a mixture thereof.

In a preferred embodiment, the heater is activated 6 to 12 hours per day, preferably 7 to 11 hours per day, more preferably 8 to 10 hours per day, most preferably about 9 hours per day.

The invention is further described by the following non-limiting examples which further illustrate the invention, and are not intended to, nor should they be interpreted to, limit the scope of the invention.

The present invention will be now described in more details, referring to examples that are not limitative.

DESCRI PTI ON OF Fl GURES

With as a goal illustrating better the properties of the invention the following presents, as an example and limiting in no way other potential applications, a description of a number of preferred applications of the method for examining the state of the grout used in a mechanical connection based on the invention, wherein:

Referring to Figures 1A and IB, there is shown a heated volatile dispensing device 20 in which a heat source is used to promote the wicking action and release of a volatile material from a wick immersed in a volatile liquid contained in a reservoir.

The dispensing device 20 includes a body 21 having a vapor outlet 24 formed in the center of the top of the body 21. A ring heater 25 having an opening extending vertically there through is provided inside the body 21 below the vapor outlet 24. The ring heater 25 is supported by a stay 26. Provided under the heater 25 is a bottle socket 27 having an opening extending vertically there through. The socket 27 is formed on its inner periphery with a threaded portion 30 adapted for threaded engagement with a threaded portion 29 on the outer periphery of the mouth 28a of a volatile liquid bottle 28.

As shown in Figure IB, the bottle 28 is provided with a wick 31 that is insertable into the ring heater 25 concentrically therewith when the bottle 28 is threaded at its mouth 28a into the socket 27. The wick 31 is immersed in the liquid 34 in the bottle 28 and upwardly transports the liquid 34 contained in the bottle 28 by capillary action.

Electrical plug blades 32 in a pair are fixed to the body 21 on its rear side. The plug blades 32 are connected to the ring heater 25 in the usual manner using electrical connections. The ring heater 25 is energized by inserting the plug blades 32 into an electrical outlet and activating switch 35 whereby the ring heater 25 produces heat to heat the upper portion of the wick 31. The heat may promote upward transport of the liquid 34 in the wick 31. The liquid chemical 34 in the wick 31 is vaporized by the heat from the ring heater 25. A more detailed description of this type of device can be found in U.S. Patent No. 5,290,546.

The wick 31 is made of the substrate as discussed below, whereupon even solutions containing natural pyrethrums can be delivered by the wick without the wick clogging, even over as much as forty-five, sixty, or more eight-hour nights, which are typical use expectations for insect control products delivering insect control actives via a wick to a heater. Such a wick 31 may be cylindrical or any other convenient shape.

Referring to Figures 2A and 2B, there is shown another heated volatile dispensing device 20a in which a heat source is used to promote the wicking action and release of a volatile material from a wick immersed in a volatile liquid contained in a reservoir. The dispensing device 20a includes a body 21 having a vapor outlet 24a formed in the center of the top of the body 21. The vapor outlet 24a includes inwardly projecting fingers 24b which define a generally rectangular opening 24c. A ring heater 25 having an opening extending vertically there through is provided inside the body 21 below the vapor outlet 24. The heater 25 is supported by a stay 26. Provided under the heater 25 is a bottle socket 27 having an opening extending vertically there through. The socket 27 is formed on its inner periphery with a threaded portion 30 adapted for threaded engagement with a threaded portion 29 on the outer periphery of the mouth 28a of a volatile liquid bottle 28.

EXAMPLE 1 AND COMPARATI VE EXAMPLE 2

The accumulation of solid residue was tested with two liquid volatile material compositions, each comprising 5 wt.% natural pyrethrins. The first composition (example 1) comprised 0.5 wt.% rosemary extract. The rosemary extract was odorless and comprised 7 wt. % carnosic acid and carnosol combined; standardized with sunflower oil. The second composition (comparative example 2) comprised 0.25 wt.% BHT.

For the BHT composition (comparative example 2), solid residue accumulation was visible after approximately 240 hours of heating. After 350 hours of heating, significant degradation of the wick was visibly noticeable. Figure 3B shows the wick of comparative example 2 after 350 hours of heating.

The composition comprising carnosic acid and carnosol (example 1) remained clean throughout its use. Figure 3A shows the wick of example 1 after 396 hours of heating.

The composition of example 1 was further tested for its efficacy against mosquitos. Satisfactory results were obtained for heating 12 hours a day and 9 hours a day throughout the testing period of 45 days.

COMPARATI VE EXAMPLES 3 AN D 4

The evaporation profile of two liquid volatile material compositions was registered, each comprising natural pyrethrins and a solvent mixture comprising isopar V and isododecane in a ratio by weight of 9: 1. Comparative example 3 comprised 10 wt.% natural pyrethrins. Comparative example 4 comprised 5 wt.% natural pyrethrins. Both compositions were tested in combination with a wooden wick.

The evaporation profile was measured by heating 8 hours a day, for 45 days. The evaporation profile was fitted to a linear evaporation profile and the correlation coefficient was calculated. As a linear, predictable evaporation profile is desired correlation coefficients close to 1 are preferred. The fitted linear evaporation profile also indicated the evaporation rate, which is the ratio of the time required to evaporate a composition.

For comparative example 4, linear evaporation was registered for the full 45 day period. The correlation coefficient of comparative example 4 was significantly higher than that of comparative example 3; thus, fitting better to its linear regression. In other words, the evaporation profile of comparative example 4 was more linear. Comparative example 4, with lower natural pyrethrin content, also showed a higher evaporation rate than example 3. COMPARATI VE EXAMPLE 5

Comparative example 5 was a repeat of comparative example 4, with the addition of 0.25 wt.% BHT. In other words, comparative example 5 comprised 5 wt.% natural pyrethrins and a solvent mixture comprising isopar V and isododecane in a ratio by weight of 9: 1. The composition further comprised 0.25 wt.% BHT and was tested in combination with a wooden wick.

Comparative example 5 showed lower correlation coefficient for a linear evaporation in regard to comparative example 4, comprising no BHT. It was also noticed that the evaporation rate dropped in regard to comparative example 4.

COMPARATI VE EXAMPLES 6

In comparative example 6, the composition of comparative example 4 was tested in combination with a bonded nylon fiber wick rather than a wooden wick.

The evaporation profile of a liquid volatile material compositions was registered, comprising 5 wt.% natural pyrethrins and a solvent mixture comprising isopar V and isododecane in a ratio by weight of 9: 1. This composition was tested with a bonded nylon (polyamide 6) fiber wick.

For the composition in combination with a wick comprising bonded nylon fibers (comparative example 6), linear evaporation was registered for 44 days for heating 12 hours a day and resulted in a higher correlation coefficient in regard to the evaporation profile of the composition in combination with a wooden wick (comparative example 4). Comparative example 6 also showed a significantly higher evaporation rate over comparative example 4. At the end of the testing period, solid residue was visible on the bonded nylon fiber wick near the heating element. The wick further expanded in this location.

EXAMPLE 7

The evaporation profile of a liquid volatile material compositions was registered, comprising 5 wt.% natural pyrethrins, a solvent mixture comprising isopar V and isododecane in a ratio by weight of 9: 1 and 0.5 wt.% rosemary extract. This composition (example 7) was tested in combination with a wick comprising bonded nylon fibers. For this composition (example 7), linear evaporation was registered and showed a significantly higher evaporation rate over the composition without rosemary extract (comparative example 6). For the composition comprising rosemary extract (example 7), the wick remained clean throughout its use. No solid residue accumulation was visible after approximately 396 hours of heating.