The present disclosure relates to perfume compositions for air freshener devices.

Controlling the release of perfume ingredients from air freshener devices is a difficult task. This is due mainly to the fact that perfume ingredients have vapour pressures spanning several orders of magnitude: The least volatile ingredients have a vapour pressure of about 0.0001 mmHg at 25 °C, whereas some of the most volatile have a vapour pressure greater than 10 mmHg at 25 °C. Hence, differential evaporation of ingredients can occur, whereupon the most volatile ingredients are exhausted much faster from an air freshener device than the less volatile ones, leading to undesired distortion of the perceived perfume character over time. For example, when evaporating from an air freshener device, a perfume composition having a citrus-woody character may lose its citrus facet within a few hours or a few days, while the less fresh and clean woody facet may remain for weeks. Consumers are not satisfied by such an evolution.

In order to address this problem, it is common to mix solvents with the perfume ingredients to obtain a more uniform evaporation of the perfume composition over time. The effect of these solvents is to lower the evaporation rate of the most volatile ingredients and to increase the evaporation rate of the less volatile ingredients.

Aside from the use of solvents for this purpose, it is also possible to use certain perfume ingredients to control the evaporation rate of air freshener perfume compositions. In order to be suitable for this purpose, such perfume ingredients are required to have low or neutral odour. Furthermore, because they would need to be employed in large amounts relative to other pleasant smelling, non-functional perfume raw materials, they should preferably display rather transparent odour characteristics, that is, the odour character should remain substantially uniform over a wide range of concentrations. Such perfume ingredients have been referred to variously in the prior art as“functional perfume components” or“potentiator compounds”, as will be more fully described herein below. Given that the substantial purpose of these ingredients is functional (that is, they are utilized in order to control the evaporation rate of a perfume composition) rather than hedonic, the applicant will refer to such perfume ingredients as“perfume fillers” in the context of the present invention.

A principal issue with solvents for use in air fresheners is that many of them have vapour pressures higher than 0.1 mmHg at 20 °C (about 13.3 Pa) and therefore may be classified as High Vapour Pressure Volatile Organic Compounds according to Californian Air Resource Board (CARB). Such solvents are of increasing environmental concern.

The prior art has addressed the CARB compliance issue. For example, US 2014/0323388 Al proposes to replace CARB non-compliant solvents with mixtures of so-called “functional perfume components”, which are relatively high vapour pressure ingredients, such as AMYL BUTYRATE (pentyl butanoate) (cited vapour pressure 0.6 mmHg at 25 °C), ETHYL ACETOACETATE (ethyl 3-oxobutanoate) (cited vapour pressure 0.9 mmHg at 25 °C) and ISOPRENYL ACETATE (prop-l-en-2-yl acetate) (cited vapour pressure 4.5 mmHg at 25 °C): These functional perfume components are used in large amounts in perfume compositions in order to adjust the evaporation profile of the perfume composition as a whole. This results in perfume compositions which are substantially free of high vapour pressure VOC solvents for air freshener and fabric refresher applications.

In US 8,603,963 Bl, a distinction is drawn between solvents categorized as High Vapour Pressure Volatile Organic Compounds (HVP-VOC) and solvents categorized as Low Vapour Pressure Volatile Organic Compounds (LVP-VOC), the latter being considered as less environmentally critical than the former. The person skilled in the art was knowledgeable of the CARB regulation requirement that manufacturers must use the environmentally less challenging LVP-VOCs, and so the alleged invention resides merely in the direction to combine CARB compliant LVP-VOCs with so-called“LVP-VOC potentiator compounds”. Unsurprisingly, whilst the patentee was compelled to use the CARB compliant LVP-VOC solvents, it proposed to use those commercially available solvents having a vapour pressure at 20 °C that are as close to but below the 0.1 mmHg CARB threshold as possible. In this regard, Dowanol DPMA (vp. 0.08 mmHg) is a LVP VOC of choice.

As for the so-called“potentiator compounds”, they merely represent a selection of known perfumery ingredients, which share a common feature in vapour pressures that are higher than 0.2 mmHg at 25 °C. Used in large amounts, these potentiator compounds compensate for the necessity of using of LVP VOC, CARB-compliant solvents.

However, whereas the prior art extensively discusses the use of these solvents, functional perfume components and potentiator compounds and their impact on the behaviour of perfume compositions evaporating under ambient conditions, it remains silent about their effects on the performance of perfume compositions at higher temperatures, e.g. 45 °C or greater, for example 50 °C, 55 °C, or 60 °C, or even 80 °C or higher, that would be encountered in active air freshener devices, such as liquid electrical air fresheners.

In many instances, however, the perfume ingredients which are disclosed in the prior art for use as functional perfume components or LVP-VOC potentiator compounds are too volatile to provide suitable evaporation profiles at the high evaporation temperatures employed in active air freshener devices.

Furthermore, in many instances, the functional perfumery components and LVP-VOC potentiator compounds disclosed in the prior art cannot be used in practice because of their unacceptably low flash points. Still further, whereas the prior art offers guidance as to how one can obtain substantially constant evaporation profiles over extended periods of time, it is silent as to the selection of solvents and other functional ingredients that can provide perfume compositions with desirable odour direction, hedonic profile and overall pleasant character. For example, certain aldehydes and ketones referred to as useful LVP-VOC potentiator compounds in US 8,603,963 Bl will generate a harsh smell that is not compatible with air freshener applications when used at high levels in perfume compositions.

In addressing the deficiencies of the prior art, the applicant surprisingly found that the vapour pressure differential between perfume ingredients is affected by temperature in an unusual way. More particularly, it was observed that for perfume ingredients having a relatively low vapour pressure at ambient temperature, the vapour pressure increased more quickly with increasing temperature than for perfume ingredients having a relatively high vapour pressure at ambient temperature. In other words, it was observed that the vapour pressure range of different perfume ingredients is substantially compressed at elevated temperatures.

As a result of this surprising observation, it was found that certain solvents and perfume fillers having very low vapour pressures at ambient temperature - and would thus appear to be uninteresting or unsuitable for use in designing perfume compositions for air freshener applications adapted for use at elevated temperatures based on the teaching of the prior art - are in fact eminently suitable for that purpose. More particularly, the applicant has discovered a novel method of identifying a perfume filler suitable for use in an air freshener device adapted to operate at a temperature of 50 °C and above. Said method comprises the steps of:

(i) measuring the weight loss of a test perfume ingredient at an elevated temperature of at least 45 °C and at a given pressure as a function of time;

(ii) determining an Initial Evaporation Slope of the weight loss of the test perfume ingredient; and

(iii) calculating a Normalized Initial Evaporation Slope of said test perfume ingredient by dividing said Initial Evaporation Slope of the weight loss of the test perfume ingredient by a Reference Initial Evaporation Slope of the weight loss of a reference ingredient measured at the same elevated temperature and the same given pressure as applied under (i), the reference ingredient being benzyl acetate; wherein said test perfume ingredient is suitable for use as a perfume filler in the air freshener device if its Normalized Initial Evaporation Slope at 65 °C has a value of about 0.10 to about 3.0. The method of the present invention enables the creation of perfume compositions containing relatively high amounts of very low vapour pressure perfume fillers that can deliver perfume with a substantially constant evaporation rate over a prolonged period of time. Furthermore, it makes available a broader palette of perfume fillers that are suitable for use in active air freshener devices. Accordingly, the invention provides in a first aspect a method of identifying a perfume filler suitable for use in an air freshener device adapted to operate at a temperature of 50 °C and above.

In a second aspect, a method of preparing a perfume composition for use in an air freshener device adapted to operate at a temperature of 50 °C and above is provided. Said method comprises the step of incorporating at least one suitable perfume filler in a concentration of at least 20% by weight of the perfume composition, wherein the at least one suitable perfume filler is identified by the method according to the present invention.

In a third aspect, the present invention provides a perfume composition for use in an air freshener device adapted to operate at a temperature of 50 °C and above. And in a fourth aspect, an air freshener device operating at a temperature higher than 50 °C is provided, said air freshener device comprising a perfume composition according to the present invention.

The present invention allows for the preparation of a perfume composition adapted for use in an active air freshener device with a substantially constant evaporation rate over a period of time greater than 30 days, preferably greater than 40 days, and more preferably greater than 60 days.

The method of the present invention, based on the Normalized Initial Evaporation Slopes of ingredients, enables perfumers to select from a broader palette of perfume fillers than was heretofore considered useful in active air freshener applications. In particular, by considering the Normalized Initial Evaporation slopes, it becomes apparent that ingredients with very low vapour pressure can be eminently useful at the relatively high operating temperatures of active air freshener devices.

Benzyl acetate has been identified as a particularly suitable perfume filler and has been chosen as a reference ingredient for the method of the present invention. Alternatively, it would also be possible to use other reference ingredients having a similar Initial Evaporation Slope, e.g. Agrumex™ (2-(tert-butyl)cyclohexyl acetate), bomyl acetate ((2S,4S)-1,7,7- trimethylbicyclo[2.2.l]heptan-2-yl acetate), tetrahydromyrcenol (2,6-dimethyloctan-2-ol), Peranat™ (2-methylpentyl 2-methylpentanoate), cyclohexyl ethyl acetate (2-cyclohexylethyl acetate), linalyl acetate (3,7-dimethylocta-l,6-dien-3-yl acetate), ALLYL OENANTHATE (prop- 2-enyl heptanoate), or DIHYDROMYRCENOL (2,6-dimethyloct-7-en-2-ol).

The Initial Evaporation Slope of the weight loss of the test perfume ingredient is advantageously determined by linear regression.

In particular, the linear regression is performed on the initial evaporation curve measured, e.g. on a weight loss range from 0% by weight to a selected upper weight loss value. The selected upper weight loss value is preferably at least 20% by weight, more preferably at least 30% by weight, even more preferably at least 40% by weight, and most preferably at least 50% by weight. The selected upper weight loss value is preferably not higher than 80% by weight.

The Initial Evaporation Slope of the weight loss of the test perfume ingredient determined by linear regression is advantageously validated by calculating the regression coefficient r . The regression coefficient is well-known to the person skilled in the art. A definition may be found at http://mathworld.wolfram.com/CorrelationCoefficient.html, for instance. The Initial Evaporation Slope is considered valid if the regression coefficient r is ³ 0.90, more preferably ³ 0.95, and most preferably ³ 0.99. Linear regression may be performed in an iterative process, starting from a wider weight loss range and consecutively selecting more and more narrow weight loss ranges in case the regression coefficient r is considered too low.

In one embodiment, the following steps are performed:

(ii-a) performing a linear regression on a weight loss range from 0% by weight to a selected upper weight loss value of 80% by weight;

(ii-b) calculating the regression coefficient r ² ; and

(ii-cl) if the regression coefficient r ² is ³ 0.99: proceeding to step (iii) of claim 1 or, alternatively,

(ii-c2) if the regression coefficient r ² is < 0.99: reducing the selected upper weight loss value; performing a linear regression on a reduced weight loss range from 0% by weight to the selected reduced upper weight loss value; and returning to step (ii-b).

The weight loss is preferably measured at an elevated temperature of at least 50 °C, preferably of at least 55 °C, more preferably of at least 60 °C, and most preferably at an elevated temperature of about 65 °C. The weight loss of the test perfume ingredient is preferably measured over a time period of at least 5 hours, more preferably of at least 8 hours.

In a preferred embodiment, the test perfume ingredient has a vapour pressure of equal to or lower than 0.9 mmHg at 25 °C.

The at least one perfume filler is preferably selected from the group consisting of 2,6- dimethylheptan-4-yl acetate; 7-isopropyl-8,8-dimethyl-6,10-dioxaspiro[4.5]decane; benzyl acetate; hexyl acetate; 2,6-dimethyloct-7-en-2-ol; 2-(sec-butyl)cyclohexanone; 3,7-dimethylocta- l,6-dien-3-ol; diethyl propanedioate; 3,5,5-trimethylhexyl acetate; 2,6-dimethylheptan-2-ol; 3,7- dimethyloctan-3-ol; ethyl heptanoate; allyl heptanoate (prop-2-enyl heptanoate); ethyl 3- oxobutanoate; 2-methylpropyl 2-methylpropanoate; ethyl 2-(2-methyl-l,3-dioxolan-2-yl)acetate; 3-isobutyl- l-methylcyclohexanol; 4-(tert-butyl)cyclohexyl acetate; (2S,4S)-l,7,7- trimethylbicyclo[2.2.l]heptan-2-yl acetate; l-phenylethyl acetate; 2-(4-methylcyclohex-3-en-l- yl)propan-2-ol; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l 2- methylpropanoate; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro- lH-4,7-methanoinden-6-yl propionate; tetrahydro-4-methyl-2-(2-methylpropyl)-2H-pyran-4-ol; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro- lH-4,7-methanoinden-6-yl acetate; (3-pentyloxan-4-yl) acetate; 2-phenylethanol; ethyl hexanoate; l-methyl-4-(prop-l-en-2-yl)cyclohex-l-ene; 3,7-dimethyloct-6-en-3-ol; (E)-3,7- dimethylnona-l,6-dien-3-ol; phenylmethanol; 2-(tert-butyl)cyclohexyl acetate; l-methyl-4- (propan-2-ylidene)cyclohex-l-ene; 2,6-dimethyloctan-2-ol; 3,7-dimethylocta-l,6-dien-3-yl acetate; and 2,6-dimethyloct-7-en-2-ol; 3-methylbutyl acetate; benzaldehyde; and mixtures thereof.

The method of the present invention may further comprise the step of incorporating at least one solvent having a vapour pressure at 20 °C of up to and including 0.1 mmHg, more particularly of up to and including 0.08 mmHg, and even more particularly of up and including 0.05 mmHg.

The at least one solvent is preferably selected from the group consisting of isoparaffinic hydrocarbon oils, low vapour pressure dibasic esters, isopropylidene glycerol (2,2-dimethyl- 1,3- dioxolan-4-yl)methanol), and mixtures thereof.

Reflecting the availability of a wider palette of useful perfume fillers, the invention provides in another of its aspects a perfume composition adapted for evaporation from an active air freshener device with a substantially constant evaporation rate over a period of time greater than 30 days, greater than 40 days, greater than 60 days, comprising at least one, more particularly at least two, perfume filler(s), and wherein the Normalized Initial Evaporation Slope at 65 °C of said at least one perfume filler has a value of about 0.10 to about 3.0.

In an embodiment, said at least one, more particularly at least two, perfume filler(s) has/have a vapour pressure lower than 0.9 mmHg at 25 °C.

The vapour pressure of perfume ingredients is typically indicated in mmHg. This can easily be converted to Pa or mbar: 1 mmHg corresponds to 133.32 Pa or 1.33322 mbar.

The applicant found that the vapour pressure differential between solvents is also substantially compressed at elevated temperatures. As a result of this discovery, the applicant has been able to create perfume compositions containing very low vapour pressure solvents, in combination with the selection of perfume fillers mentioned hereinabove.

Accordingly, the invention provides in yet another aspect, a perfume composition adapted for evaporation from an active air freshener device with a substantially constant evaporation rate over a period of time greater than 30 days, greater than 40 days, greater than 60 days, wherein said perfume composition comprises at least one, more particularly at least two perfume filler(s), and optionally one or more solvents, and wherein the Normalized Initial Evaporation Slope at 65 °C of said at least one perfume filler has a value of about 0.10 to about 3.0; and wherein said at least one, more particularly at least two perfume filler(s) has a vapour pressure lower than 0.9 mmHg at 25 °C and, optionally, one or more solvents having a vapour pressure, or a weight average vapor pressure, of less than 0.08 mmHg at 20 °C, more particularly, of less than 0.05 mmHg at 20 °C.

The perfume composition of the present invention advantageouosly comprises (a) at least 20 wt% of at least one suitable perfume filler having a Normalized Initial Evaporation Slope at 65 °C of about 0.10 to about 3.0 and (b) at least one solvent having a vapour pressure of up to and including 0.1 mmHg at 20 °C.

Preferably, the at least one perfume filler is selected from the group consisting of 2,6- dimethylheptan-4-yl acetate; 7-isopropyl-8,8-dimethyl-6,l0-dioxaspiro[4.5]decane; benzyl acetate; hexyl acetate; 2,6-dimethyloct-7-en-2-ol; 2-(sec-butyl)cyclohexanone; 3,7-dimethylocta- l,6-dien-3-ol; diethyl propanedioate; 3,5,5-trimethylhexyl acetate; 2,6-dimethylheptan-2-ol; 3,7- dimethyloctan-3-ol; ethyl heptanoate; allyl heptanoate (prop-2-enyl heptanoate); ethyl 3- oxobutanoate; 2-methylpropyl 2-methylpropanoate; ethyl 2-(2-methyl-l,3-dioxolan-2-yl)acetate; 3-isobutyl- l-methylcyclohexanol; 4-(tert-butyl)cyclohexyl acetate; (2S,4S)-l,7,7- trimethylbicyclo[2.2.l]heptan-2-yl acetate; l-phenylethyl acetate; 2-(4-methylcyclohex-3-en-l- yl)propan-2-ol; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l 2- methylpropanoate; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l propionate; tetrahydro-4-methyl-2-(2-methylpropyl)-2H-pyran-4-ol; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro- lH-4,7-methanoinden-6-yl acetate; (3-pentyloxan-4-yl) acetate; 2-phenylethanol; ethyl hexanoate; l-methyl-4-(prop- l-en-2-yl)cyclohex- l-ene; 3,7-dimethyloct-6-en-3-ol; (E)-3,7-dimethylnona- l,6-dien-3-ol; phenylmethanol; 2-(tert-butyl)cyclohexyl acetate; 1 -methyl-4- (propan-2- ylidene)cyclohex- l-ene; 2,6-dimethyloctan-2-ol; 3,7-dimethylocta-l,6-dien-3-yl acetate; and 2,6- dimethyloct-7-en-2-ol; 3-methylbutyl acetate; benzaldehyde; and mixtures thereof. The air freshener device of the present invention operates at a temperature higher than 50 °C, more particularly higher than 60 °C, more particularly higher than 70 °C and still more particularly higher than 80 °C, and comprises a perfume composition as defined above.

In an embodiment, a plug-in electrical air freshener device is provided. These and other aspects and embodiments of the invention will be more fully described in the following detailed specification.

The present invention is based on the surprising finding that at elevated temperatures, typically experienced in the operation of high-temperature emanating devices, such as liquid electrical air freshener devices, the vapour pressure distribution of ingredients in a perfume composition is surprisingly much narrower than that prevailing at ambient temperature. The vapour pressures of the ingredients having a relatively low vapour pressure at room temperature increased considerably faster with increasing temperature compared to those of ingredients having a relatively high vapour pressure at room temperature. This observation could not be anticipated from the prior art. This effect is illustrated in Figure 1, which shows the vapour pressure response of selected perfume ingredients as a function of temperature. What is demonstrated clearly is that vapour pressure of the relatively non-volatile molecule GARDOCYCLENE ((3aR,6S,7aS)-3a,4,5,6,7,7a- hexahydro-lH-4,7-methanoinden-6-yl isobutanoate2-methylpropanoate); (relative to a reference perfume ingredient, e.g. BENZYL ACETATE) has a far more pronounced response to increased temperature than that of the relatively more volatile ISOAMYLACETATE (3-methylbutyl acetate).

The selection of BENZYL ACETATE as a reference ingredient is made on the basis that it is a perfume ingredient having an intermediate vapour pressure among the perfume ingredients useful in air freshener applications. It is also a useful perfume ingredient in air freshener devices working at both ambient and elevated temperatures. Taking BENZYL ACETATE as a reference ingredient (see table 1 below) illustrates that the vapour pressure of highly volatile ingredients is much less sensitive to increasing temperature than that of non-volatile ingredients. BENZYL ACETATE has the following vapour pressure: 0.20 mmHg at 25 °C; 0.86 mmHg at 45 °C; 2.96 mmHg at 65 °C; and 8.64 mmHg at 85 °C. Alternatively, it would also be possible to use Agrumex™ (2-(tert-butyl)cyclohexyl acetate), bornyl acetate ((2S,4S)-1,7,7-trimethylbicyclo[2.2.l]heptan-2-yl acetate), tetrahydromyrcenol (2,6-dimethyloctan-2-ol), Peranat™ (2-methylpentyl 2-methylpentanoate), cyclohexyl ethyl acetate (2-cyclohexylethyl acetate), linalyl acetate (3,7-dimethylocta-1,6-dien-3-yl acetate), ALLYL OENANTHATE (prop-2-enyl heptanoate),, or DIH YDROM YRCEN OL (2,6- dimethyloct-7-en-2-ol) as the reference ingredient to determine the Normalized Initial Evaporation Slope of a subject perfume ingredient.

On the other hand, as described in more detail hereafter, the vapour pressure of an ingredient at a given temperature is correlated with the initial slope of the evaporation curve of this ingredient at that given temperature. The Normalized Initial Evaporation Slope of a test perfume ingredient is obtained by dividing the initial slope of the evaporation curve of said test perfume ingredient by the initial slope of the evaporation curve of the selected reference ingredient, i.e. BENZYL ACETATE.

The initial slope of the evaporation curve is determined by measuring the weight loss of the subject perfume ingredient in an air freshener as a function of time at the working temperature. The weight loss function monitors the change of weight as a function of time, (F(t)), expressed in % by weight (wt%) (Equation 1):

F(t) = [w(to) - w(t)]/w(to) (Equation 1), wherein w(t) is the weight at a given time t and w(t ₀ ) is the weight at the starting time t ₀ . As shown in Figure 2, this weight loss function is substantially linear within a large interval of time but tends to level off over longer time periods as the amount of evaporating ingredient tends towards zero. The substantially constant weight loss is characterized by said initial slope.

Figure 2 shows also schematically how the initial slope is determined by linear regression. In Figure 2, the evaporation curves are represented by thick plain (high volatility), dotted (intermediate volatility) and dashed lines (low volatility), respectively, and the initial slopes by thin plain (high volatility), dotted (intermediate volatility) and dashed lines (low volatility), respectively. The concept of evaporation curves in the context of active and passive air fresheners is well known in the art, for example from EP 0 462 605 A2, WO 2001/062308 A1, and US 2011/0192912 A1.

The values of the Normalized Initial Evaporation Slope of selected perfume ingredients useful as perfume fillers in the context of the present invention are reported in Table 1.

Table 1: Normalized initial evaporation slopes of selected perfume fillers to initial evaporation slope of benzyl acetate as a function of temperature

As is apparent from table 1, the ratio between the Normalized Initial Evaporation Slope of the evaporation curve of the most volatile filler (i.e. ISOAMYL ACETATE) and the normalized initial evaporation slope of the evaporation curve of a less volatile filler (GARDOCYCLENE) decreases from 2.2 orders of magnitude to 1.4 orders of magnitude when the temperature is increased from 45 °C to 85 °C.

Based on this surprising finding, the applicant has been able to identify a much broader selection of perfume ingredients suitable as perfume fillers for use at elevated temperature, which prove to be extremely useful in active air freshener devices, and especially in liquid electrical air freshener devices. In particular, it has been found that low vapour pressure perfume fillers with a vapour pressure below 0.2 mmHg at 25 °C, which are considered in the prior art as inefficient as perfume fillers for air freshener perfume compositions, can be very effective fillers at the elevated operational temperatures of active air freshener devices.

The use of the perfume fillers identifed in accordance with the method of the present invention has multiple benefits. In particular, by using low vapour pressure perfume fillers, it is possible to obtain perfume compositions having high flash points, which is particularly desirable for the sake of safety during transportation and handling of said perfume compositions. Furthermore, by widening the palette of suitable perfume fillers, the skilled perfumer has wider ingredients’ palette to develop hedonically pleasant perfume compositions, having more diverse odours. The term“flash point” is well known in the art, and is intended here to represent the lowest temperature at which vapours of a material will ignite in the presence of a source of ignition.

In an embodiment of the invention, a perfume composition contains at least one, more particularly at least two perfume fillers having a vapour pressure lower than 0.2 mmHg at 25 °C.

Particular perfume fillers having a vapour pressure lower than 0.2 mmHg at 25 °C include (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l 2-methylpropanoate, for example GARDOCYCLENE; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l propionate, for example FLOROCYCLENE; tetrahydro-4-methyl-2-(2-methylpropyl)-2H-pyran- 4-ol, for example FLOROSA HC; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden- 6-yl acetate, for example JASMACYCLENE; (3-pentyloxan-4-yl) acetate, for example JASMONYL™; 2-phenylethanol, for example PHENYL ETHYL ALCOHOL; 3,7-dimethyloct- 6-en-3-ol, for example DIHYDRO LINALOOL; (E)-3,7-dimethylnona-l,6-dien-3-ol, for example ETHYL LINALOOL; phenylmethanol, for example BENZYL ALCOHOL EXTRA; 2-(tert- butyl)cyclohexyl acetate, for example AGRUMEX™; 2,6-dimethyloctan-2-ol, for example TETRAHYDRO MYRCENOL; 3,7-dimethylocta-l,6-dien-3-yl acetate, for example LINALYL ACETATE; and 2,6-dimethyloct-7-en-2-ol, for example DIMYRCETOL.

In an embodiment of the invention, the perfume composition contains at least one, more particularly at least two perfume fillers having a Normalized Initial Evaporation Slope at 65 °C ranging from about 0.5 to about 3, selected from the group consisting of 2,6-dimethylheptan-4-yl acetate, for example ALICATE; 7-isopropyl-8,8-dimethyl-6,l0-dioxaspiro[4.5]decane, for example OPALAL™; benzyl acetate,; 2,6-dimethyloct-7-en-2-ol, for example DIHYDRO MYRCENOL; 2-(sec-butyl)cyclohexanone, for example FRESKOMENTHE; 3,7-dimethylocta- l,6-dien-3-ol, for example LINALOOL; diethyl propanedioate, for example DIETHYL MALONATE; 3,5,5-trimethylhexyl acetate, for example ISONONANYL ACETATE; 2,6- dimethylhep tan-2- ol, for example DIMETOL; 3,7-dimethyloctan-3-ol, for example TETRAHYDRO LINALOOL; ethyl heptanoate, for example ETHYL OENANTHATE; ethyl 3- oxobutanoate, for example ETHYL ACETOACETATE; 2-methylpropyl 2-methylpropanoate, for example ISOBUTYL ISOBUTYRATE; ethyl 2-(2-methyl-l,3-dioxolan-2-yl)acetate, for example FRUCTONE; 3 -isobutyl- l-methylcyclohexanol, for example ROSSITOL™; 4-(tert- butyl)cyclohexyl acetate, for example PARA-TERT-BUTYL-CYCLOHEXYL ACETATE; (2S,4S)-l,7,7-trimethylbicyclo[2.2.l]heptan-2-yl acetate, for example BORNYL ACETATE; 1- phenylethyl acetate, for example GARDENOL; 2-(4-methylcyclohex-3-en-l-yl)propan-2-ol, for example TERPINEOL PURE; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH-4,7-methanoinden-6-y l 2-methylbutanoate, for example GARDOCYCLENE; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro-lH- 4,7-methanoinden-6-yl propionate, for example FLOROCYCLENE; tetrahydro-4-methyl-2-(2- methylpropyl)-2H-pyran-4-ol, for example FLOROSA; (3aR,6S,7aS)-3a,4,5,6,7,7a-hexahydro- lH-4,7-methanoinden-6-yl acetate, for example JASMACYCLENE; (3-pentyloxan-4-yl) acetate, for example JASMONYL™; 2-phenylethanol, for example PHENYL ETHYL ALCOHOL; 3,7- dimethyloct-6-en-3-ol, for example DIHYDRO LINALOOL; (E)-3,7-dimethylnona-l,6-dien-3-ol, for example ETHYL LINALOOL; phenylmethanol, for example BENZYL ALCOHOL; 2-(tert- butyl)cyclohexyl acetate, for example AGRUMEX™; 2,6-dimethyloctan-2-ol, for example TETRAHYDRO MYRCENOL; 3,7-dimethylocta-l,6-dien-3-yl acetate, for example LIN ALYL; 2,6-dimethyloct-7-en-2-ol, for example DIMYRCETOL; and mixtures thereof. The perfume fillers according to this embodiment have a vapour pressure lower than or equal to about 0.9 mmHg at 25 °C, which corresponds to the vapour pressure of ETHYL ACETOACETATE (ethyl 3-oxobutanoate) at 25 °C.

In an embodiment of the invention, the perfume composition the at least one, more particularly at least two perfume fillers having a Normalized Initial Evaporation Slope at 65 °C ranging from about from about 0.1 to about 3, which is/are present in the perfume composition at a level of at least 20 wt%, more particularly at least 25 wt%, more particularly at least 30 wt%, based on total perfume composition.

In an embodiment of the invention, a perfume composition may contain at least one perfume filler having a higher vapour pressure than ETHYL ACETOACETATE, selected from the group consisting of ethyl hexanoate, ETHYL CAPRONATE; benzaldehyde; 1 -methyl-4- (prop- l-en-2- yl)cyclohex-l-ene, for example DIPENTENE; hexyl acetate, for example HEXYL ACETATE; ((4S)-l-methyl-4-prop-l-en-2-ylcyclohex-l-ene), for example L-limonene or LIMONENE LAEVO; l-methyl-4-(propan-2-ylidene)cyclohex-l-ene, for example TERPINOLENE; isopentyl acetate, for example ISOAMYL ACETATE, provided that the flash point of the perfume composition remains within an acceptable range, for example higher than 60 °C.

A number of suitable perfume fillers, one or more of which may be used in certain perfume compositions, are outlined in Table 2:

The amount of individual perfume fillers employed in a perfume composition according to the present invention may vary depending on the effect that is desired to be achieved. Operative levels include 0 to 99 wt%, more particularly 1 to 50 wt%. Useful levels for selected individual perfumer fillers are provided in table 3, below. Table 3: Typical concentration ranges of perfume fillers in perfume compositions suitable for use in active air freshener devices operating at a temperature of higher than 50 °C, for example at 55 °C, or 60 °C, or 80 °C

Preferred concentration ranges of the above-mentioned individual perfume ingredients are reported in Table 4.

Table 4: Preferred concentration ranges of perfume fillers in perfume compositions suitable for use in active air freshener devices operating at a temperature of higher than 50 °C, for example at 55 °C, or 60 °C, or 80 °C

In an embodiment of the invention, the perfume compositions according to the invention may optionally comprise solvents having a vapour pressure below 0.1 mmHg at 20 °C, more particularly below 0.08 mmHg at 20 °C, and more particularly still below 0.05 mmHg at 20 °C. Such a solvent may be selected from the group consisting of TRIPROPYLENE GLYCOL METHYL ETHER (2-[2-(2-methoxypropoxy)propoxy]propan-l-ol), for example DOWANOL TPM (0.01 mmHg at 20 °C), ex Dow Chemicals; DIPROPYLENE GLYCOL METHYL ETHER ACETATE (l-(3-methoxypropoxy)propyl acetate), for example DOWANOL DPMA (0.08 mmHg at 20 °C), ex Dow Chemicals; DIPROPYLENE GLYCOL n-PROPYL ETHER (1,4- dimethyl-3,6-dioxanonane-l-ol)) (0.04 mmHg at 20 °C), for example DOWANOL DPnP, ex Dow Chemicals; DIPROPYLENE GLYCOL n-BUTYL ETHER (l-(l-butoxypropan-2- yloxy)propan-2-ol), for example DOWANOL DPnB (not measured), ex Dow Chemicals; DIPROPYLENE GLYCOL (90% 4-oxa-2,6-hexandiol, 10% 4-oxa-l,6-hexandiol) (0.0009 mmHg at 20 °C), PROPYLENE GLYCOL (propane- l,2-diol) (0.1 mmHg at 20 °C), isoparaffinic hydrocarbon oils, for example ISOPAR M - Z, ex Exxon, dibasic esters (DBEs), such as mixtures of DIMETHYL GLUTARATE (dimethyl pentanedioate), DIMETHYL SUCCINATE (dimethyl butanedioate) and DIMETHYL ADIPATE (dimethyl hexanedioate), for example FLEXISOLVE DBE-2, FLEXISOLVE DBE-3, FLEXISOLVE DBE-5, FLEXISOLVE DBE-6, and FLEXISOLVE DBE-7; ISOPROPYLIDENE GLYCEROL (2, 2-dimethyl- l,3-dioxolane-4- methanol), for example AUGEO-CLEAN MULTI (0.04 mmHg at 20 °C), ex Solvay; ETHYLENE GLYCOL DIBENZOATE (2-benzoyloxyethyl benzoate) , for example BENZOFLEX P200 (not measured), ex Eastman, and mixtures thereof.

The skilled person will understand that if a mixture of solvents is employed, the vapour pressure ranges referred to herein above refer to the weight average vapour pressure of the mixture.

In a preferred embodiment, solvents useful in perfume compositions according to the invention include, but are not limited to dibasic esters comprising from about 0 to about 100 wt% DIMETHYL GLUTARATE, from about 0 to about 100 wt% DIMETHYL ADIPATE, and/or from about 0 to about 50 wt% DIMETHYL SUCCINATE, for example FlexiSolv™ DBE ^® -esters (weight average vapour pressures ranging from 0.02 to 0.07 mmHg at 20 °C), ex Flexisolve Technology; isoparaffinic hydrocarbon oils, for example ISOPAR M to Z (weight average vapour pressure below 0.09 mmHg at 20 °C), ex Exxon; and (2, 2-dimethyl- l,3-dioxolane-4-methanol), for example AUGEO-CLEAN MULTI (0.04 mmHg at 20 °C), ex Rhodia; and mixtures thereof.

In a preferred embodiment, solvents useful in perfume compositions according to the invention have a vapour pressure or a weight average vapour pressure at 20 °C below 0.05 mmHg at 20 °C and include, but are not limited to low vapour pressure dibasic esters (LVP DBEs) comprising from about 60 to about 80 wt% DIMETHYL GLUTARATE and from about 15 to about 35 wt% DIMETHYL ADIPATE, for example FlexiSolv™ DBE®-LVP esters (weight average vapour pressure 0.04 mmHg at 20 °C), and (2,2-dimethyl- l,3-dioxolane-4-methanol), for example AUGEO-CLEAN MULTI (0.04 mmHg at 20 °C).

The amount of at least one solvent selected according to the above mentioned criteria that is employed in a perfume composition according to the present invention may vary depending on the effect that is desired to be achieved. Operative levels include from about 0 to about 70% for all solvents mentioned hereinabove, and more particularly 0 to 30 wt%, and more particularly still 0 to 10 wt% for PROPYLENE GLYCOL or about 0 to about 10 wt% for ISOPAR mixtures.

In addition to the perfume fillers and solvents selected in accordance with the above criteria referred to hereinabove, perfume compositions of the present invention may contain additional ingredients, such as any of the CARB-compliant LVP VOC solvents referred to in US 8,603,963 Bl, and additional perfume ingredients that are selected, primarily on the basis of the hedonic effects that they will bring to a perfume composition. Such additional perfume ingredients may be selected from natural products such as essential oils, absolutes, resinoids, resins, concretes, and synthetic perfume components such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, acetals, ketals and nitriles, including saturated and unsaturated compounds, aliphatic, carbocyclic and heterocyclic compounds, or precursors of any of the above. Other examples of odorant compositions which may be used are described in H 1468 (United States Statutory Invention Registration, or in S. Arctander“Perfume and Flavor Chemicals: Volume 1”, Allured Publishing Corporation 1969, or any later editions thereof, as well as the IFRA (International Fragrance Research Association) database, and RIFM (Research Institute of Fragrance Materials) database, each of which and hereby incorporated by reference in their entirety.

Suitable additional perfume ingredients that are useful in perfume compositions according to the invention include, but are not limited to, 2-METHYL 2-PENTENOIC ACID (2-methyl-pent-2- enoic acid); ACETOIN (3-hydroxybutan-2-one); ACETOPHENONE EXTRA (acetophenone); AGRUMEX™ (2-(tert-butyl)cyclohexyl acetate); ALCOHOL C 9 NONYLIC (nonan-l-ol); ALDEHYDE C 10 DECYLIC (decanal); ALDEHYDE C 11 UNDECYLENIC (undec-lO-enal); ALDEHYDE C 12 LAURIC (dodecanal); ALDEHYDE C 6 HEXYLIC (Hexan-l-ol); ALDEHYDE C 8 OCTYLIC (octanal); ALDEHYDE C 9 NONYLIC (nonanal); ALLYL AMYL GLYCOLATE (prop-2-enyl 2-(3-methylbutoxy)acetate ); ALLYL CYCLOHEXYL PROPIONATE (prop-2-enyl 3-cyclohexylpropionate); AMBRETTOLIDE ((Z)- oxacycloheptadec- 10-en-2-one) ; AMBROFIX (3a,6,6,9a-tetramethyldodecahydronaphtho[2, 1 - b]furan); ANETHOLE SYNTHETIC ((E)-l-methoxy-4-(prop-l-en-l-yl)benzene); ANJERUK ^® (l-phenylethanethiol); APHERMATE (1-(3,3-dimethylcyclohexyl)ethyl formate); AUBEPINE PARA CRESOL (4-methoxybenzaldehyde); BICYCLO NONALACTONE (octahydro-2H- chromen-2-one); BORNEOL CRYSTALS ((lS,2S,4S)-l,7,7-trimethylbicyclo[2.2.1]heptan-2-ol); BUTYL ACETATE (butyl acetate); BUTYL BUTYRO LACTATE (l-butoxy-l-oxopropan-2-yl butanoate); CARVONE LAEVO (2-methyl-5-(prop-l-en-2-yl)cyclohex-2-enone); CASHMERAN ^® (1,1,2,3,3-pentamethyl-2,3,6,7-tetrahydro-1H-inden-4(5H)-one );

CASSYRANE ^® (5-tert-butyl-2-methyl-5-propyl-2H-furan); CEDRYL METHYL ETHER ((lR,6S,8aS)-6-methoxy-1,4,4,6-tetramethyloctahydro-lH-5,8a- methanoazulene); CETALOX ^® (3a,6,6,9a-tetramethyl-2,4,5,5a,7,8,9,9b-octahydro-lH-benzo[ e][l]benzofuran); CINNAMALVA (cinnamonitrile); CINNAMIC ALDEHYDE (cinnamaldehyde); CINNAMYL ACETATE (cinnamyl acetate); CITRAL TECH ((E)-3,7-dimethylocta-2,6-dienal); CITRONELLOL (3,7- dimethyloct-6-en-l-ol); CITRONELLYL ACETATE (3,7-dimethyloct-6-en-l-yl acetate); CITRONELLYL OXYACETALDEHYDE (2-((3,7-dimethyloct-6-en- l-yl)oxy)acetaldehyde); CONIFERAN ^® (2-(tert-pentyl)cyclohexyl acetate); COUMARIN (2H-chromen-2-one); CYCLAL C (2,4-dimethylcyclohex-3-enecarbaldehyde); CYCLAMEN ALDEHYDE (3-(4- isopropylphenyl)-2-methylpropanal); CYCLOGALBANATE (prop-2-enyl 2-

(cyclohexyloxy) acetate) ; CY CLOHEXAL (4-(4-hydroxy-4-methylpentyl)cyclohex-3- enecarbaldehyde); CYMENE PARA (p-cymene); CYPRISATE (methyl 1,4- dimethylcyclohexanecarboxylate); DAMASCENONE ((E)-l-(2,6,6-trimethylcyclohexa-1,3-dien- l-yl)but-2-en-l-one); DAMASCONE ALPHA ((E)-l-(2,6,6-trimethylcyclohex-2-en-l-yl)but-2- en-l-one); DAMASCONE DELTA ((E)-l-(2,6,6-trimethylcyclohex-3-en-l-yl)but-2-en-l-one); DECALACTONE GAMMA (5-hexyloxolan-2-one); DECENAL-4-TRANS ((E)-dec-4-enal); DIHYDRO EUGENOL (2-methoxy-4-propylphenol); DIHYDRO MYRCENOL (2,6- dimethyloct-7 -en-2-ol) ; DIMETHYL BENZYL CARBINYL ACETATE (2-methyl- 1- phenylpropan-2-yl acetate); DIMETHYL BENZYL CARBINYL BUTYRATE (2-methyl- 1- phenylpropan-2-yl butanoate; DODECALACTONE DELTA (6-heptyltetrahydro-2H-pyran-2- one); EBANOL ^® ((E)-3-methyl-5-(2,2,3-trimethylcyclopent-3-en- l-yl)pent-4-en-2-ol); ELINTAAL (3-(l-ethoxyethoxy)-3,7-dimethylocta-l, 6-diene); ETHYL BUTYRATE (ethyl butanoate); ETHYL ISOAMYL KETONE (6-methylheptan-3-one); ETHYL ISOVALERATE (ethyl 3-methylbutanoate); ETHYL LINALOOL ((E)-3,7-dimethylnona-1,6-dien-3-ol); ETHYL MALTOL (2-ethyl-3-hydroxy-4H-pyran-4-one); ETHYL METHYL-2-BUTYRATE (ethyl 2- methylbutanoate); ETHYL SAFRANATE (ethyl 2,6,6-trimethylcyclohexa-l,3-diene-l- carboxylate); ETHYL VANILLIN (3-ethoxy-4-hydroxybenzaldehyde); EUCALYPTOL ((ls,4s)-

1.3.3-trimethyl-2-oxabicyclo[2.2.2]octane); EUGENOL (2-methoxy-4-prop-2-enylphenol); EVERNYL (methyl 2,4-dihydroxy-3,6-dimethylbenzoate); FENCHYL ALCOHOL ((lS,2R,4R)-

1.3.3-trimethylbicyclo[2.2. l]heptan-2-ol); FLORALOZONE ^® (3-(4-ethylphenyl)-2,2- dimethylpropanal); FLORHYDRAL ^® (3-(3-isopropylphenyl)butanal); FLORIDILE ^® ((E)-undec- 9-enenitrile); FLOROPAL ^® (2,4,6-trimethyl-4-phenyl-l,3-dioxane); GALBANONE (l-(3,3- dimethylcyclohex- 1 -en- 1 -yl)pent-4-en- 1 -one) ; GERANIOL ((E)-3 ,7 -dimethylocta-2,6-dien- 1 -ol) ; HEDIONE (methyl 3-oxo-2-pentylcyclopentaneacetate); HELIOTROPINE CRYSTALS (benzo[d][l,3]dioxole-5-carbaldehyde); HEXENYL ACETATE CIS-3 (cis-hex-3-enyl acetate); HEXENYL-3-CIS BENZOATE ((Z)-hex-3-en-l-yl benzoate); HEXENYL- 3 -CIS SALICYLATE ((Z)-hex-3-en-l-yl 2-hydroxybenzoate); HEXYL BUTYRATE (hexyl butanoate); HEXYL ISOBUTYRATE (hexyl isobutanoate); IONONE BETA ((E)-4-(2,6,6-trimethylcyclohex-l-en-l- yl)but-3-en-2-one); IRISONE PURE ((E)-4-(2,6,6-trimethylcyclohex-2-en-l-yl)but-3-en-2-one); ISO E SUPER ^® (l-(2,3,8,8-tetramethyl-l,2,3,4,5,6,7,8-octahydronaphthalen- 2-yl)ethanone); ISOAMYL BUTYRATE (isopentyl butanoate); ISOCYCLOCITRAL (2,4,6-trimethylcyclohex-3- enecarbaldehyde); ISOEUGENOL ((E)-2-methoxy-4-(prop-l-en-l-yl)phenol); ISOMENTHONE DL (2-isopropyl-5-methylcyclohexanone); ISOPENTYL ISOVALERATE (isopentyl 3- methylbutanoate); ISOPROPYL-2 METHYL-4 THIAZOLE (2-isopropyl-4-methylthiazole); ISORALDEINE ^® 70 ((E)-3-methyl-4-(2,6,6-trimethylcyclohex-2-en- l-yl)but-3-en-2-one); JASMATONE ^® (2-hexylcyclopentanone); JAVANOL ^® (( l-methyl-2-(( 1,2,2- trimethylbicyclo[3.1.0]hexan-3-yl)methyl)cyclopropyl)methano l); KOHINOOL ^® (3, 4, 5,6,6- pentamethylhep tan-2- ol); LABIENOXIME ((3E,6E)-2,4,4,7-tetramethylnona-6,8-dien-3-one oxime); LEMONILE ^® ((2E,6Z)-3,7-dimethylnona-2,6-dienenitrile); LIFFAROME ^® ((Z)-hex-3- en-l-yl methyl carbonate); MACEAL (bicyclo[2.2.2]oct-5-ene-2-carboxaldehyde); MANZANATE (ethyl 2-methylpentanoate); MENTHOL (2-isopropyl-5-methylcyclohexanol); METHOXY PHENYL BUTANONE (4-(4-methoxyphenyl)butan-2-one); METHYL AMYL KETONE (heptan-2-one); METHYL ANTHRANILATE (methyl 2-aminobenzoate); METHYL CINNAMATE (methyl cinnamate); METHYL HEPTENONE (6-methylhept-5-en-2-one); METHYL HEXYL KETONE (octan-2-one); METHYL PAMPLEMOUSSE ^® (6,6-dimethoxy- 2,5,5-trimethylhex-2-ene); MUSK C14 (l,4-dioxacyclohexadecane-5,l6-dione); MYRCENE 90 (7-methyl-3-methyleneocta-l, 6-diene); NEOFOLIONE ((E)-methyl non-2-enoate); ORANGER CRYSTALS (l-(2-naphtalenyl)-ethanone); OXANE ^® 50%/TEC (2-methyl-4-propyl-1,3- oxathiane); OXYOCTALINE FORMATE (2,4a,5,8a-tetramethyl-1,2,3,4,4a,7,8,8a- octahydronaphthalen-l-yl formate); PARADISAMIDE ^® (2-ethyl-N-methyl-N-(m- tolyl)butanamide); PEACH PURE (5-heptyldihydrofuran-2(3H)-one); PELARGOL (3,7- dimethyloctan-l-ol); PHENOXY ACETALDEHYDE 50 (2-phenoxyacetaldehyde); PRUNOLIDE (5-pentyldihydrofuran-2(3H)-one); RADJANOL ^® ((E)-2-ethyl-4-(2,2,3- trimethylcyclopent-3-en-l-yl)but-2-en-l-ol); RASPBERRY KETONE (N112) (4-(4- hydroxyphenyl)butan-2-one) ; RESEDAL (2-(cyclohexylmethyl)-4, 4, 6-trimethyl- 1 ,3-dioxane) ; RHUBAFURAN ^® (2,4-dimethyl-4-phenyltetrahydrofuran); STRAWBERRY PURE (ethyl methyl phenyl glycidate); SYLKOLIDE ^® ((E)-2-((3,5-dimethylhex-3-en-2-yl)oxy)-2- methylpropyl cyclopropanecarboxylate); TERPENYL ACETATE (2-(4-methylcyclohex-3-en-l- yl)propan-2-yl acetate); THYMOL CRYSTALS (2-isopropyl-5-methylphenol); TRANS-2- HEXENAL (E-hex-2-enal); TRICYCLAL (2,4-dimethylcyclohex-3-enecarbaldehyde); TRIFERNAL (3-phenylbutanal); TRIMOFIX O ^® (l-((2E,5Z,9Z)-2,7,8-trimethylcyclododeca- 2,5 ,9-trien- 1 -yl)ethanone) ; UNDECAVERTOL ((E)-4-methyldec-3-en-5-ol); VANILLIN (4- hydroxy- 3 -methoxybenzaldehyde); ZINARINE (2-(2,4-dimethylcyclohexyl)pyridine).

Perfume compositions according to the present invention are suitable for use in active air freshener devices. By“active air freshener devices” is meant any air freshener device in which heat is applied to promote evaporation of air freshening perfume compositions, wherein, in the context of the present disclosure, the air freshening perfume composition is liquid. Such devices include especially so-called liquid electrical plug-in air fresheners, where the liquid is conducted through a porous wick to an electrically heated evaporation chamber, comprising optionally a fan. However, other devices may also be considered in the context of this invention, wherein an open reservoir, such as a cup, is heated by an electrical resistance, thermo -element, a votive candle flame, a gas flame, and the like. Active air fresheners operate at various temperatures higher than room temperature.

The operating temperature of such active air freshener devices is about 50 °C, more about 60 °C, more particularly 65 °C, more particularly still above 70 °C and more particularly still 80 °C or above. During operation, the perfume composition evaporates and is transported to the surroundings by diffusion and convection.

The efficiency of an active air freshener device is determined by the amount of perfume composition released to an atmosphere during a certain period of time, for example 30 days or 40 days or 60 days. During this period of time, which is also referred as the life time of the air freshener, it is expected that the following conditions are fulfilled: (i) the rate of perfume release into the atmosphere is continuous and nearly constant, that is, the rate release does not change significantly with time. Indeed, typically a constant rate of evaporation from an active air- freshener device is the loss to evaporation lies with a range of about 0.3 gram/day to about 0.8 gram/day; (ii) the profile of the perfume remains nearly constant, i.e. the odour character of the perfume remains essentially unchanged over time and (iii) the perfume is released in such a way that the totality of the perfume has evaporated during the lifetime of the air freshener, i.e. there is no perfume residue left in the device.

There now follows a series of examples that are provided solely for the purpose of illustration and are not intended to be limiting on the invention

Example 1: Vapour pressure measurements and normalization

The weight loss function of a series of perfume ingredients was measured by monitoring the weight loss of 0.2 g of ingredient absorbed on 0.2 g of a polyester wick, using an infra-red balance Mettler Excellence HS-153 at 45 °C, 65 °C and 85 °C. The results were normalized by dividing the value of the initial slope of the weight loss function of this ingredient by that of BENZYL ACETATE.

The values are reported in Table 1 above.

Example 2: Air freshener compositions

In this example, air freshener compositions according to the present disclosure (A and C) have been prepared and evaluated against compositions according to US 8,603,963 Bl (B and D).

Table 5: Air freshener compositions (all numbers are in wt%)

Example 3: Evaporation measurements

In this example, the evaporation of air freshener compositions according to the present disclosure (formulae G1 and G2) has been compared to compositions according to US 8,603,963 B1 (formulae E and F). The device temperature was 80 °C. The formulae of these compositions are reported in Table 6.

Table 6: Compositions and weight losses at 80 °C (comparative examples) (all numbers are in wt%)

The weight loss function was measured at 80 °C, giving for sample G2 weight losses of 30.5 wt% after 8 days, 51 wt% after 15 days and 90 wt% after 30 days, and for G1, 32 wt% after 8 days, 54 wt% after 15 days and 92 wt% after 30 days. In contrast, samples E and F were empty or almost empty after 15 days (weight loss larger than 90 wt%). As apparent from the above results, the present disclosure provides selection rules for solvents and fillers that are suitable for air freshener devices operating at high temperature, while, on the contrary, compositions according to the prior art evaporate too quickly at such elevated temperatures. Furthermore, compositions G1 and G2 are hedonically much better than compositions E and F, as confirmed by an expert panel of 5 evaluators. Example 4

In this example, air freshener compositions according to the present disclosure, having specifically designed odour directions have been prepared. The selection of the solvents and perfume fillers is not only driven by compliance to CARB regulation, as disclosed in US 8,603,963 Bl, but also according to hedonic considerations.

Table 7: Combinations of solvents and perfume fillers for selected odour directions (the number are in wt%)

Example 5

In this example, air freshener compositions according to the present disclosure and especially suitable for an operating temperature of 80 °C, are disclosed. The concentration of solvents, perfume fillers and other perfume ingredients having vapour pressure higher than 0.2 mmHg at 25 °C is lower than 10 wt% of the whole composition. Both vapour pressure in mmHg units and measured standard equilibrium concentrations are given. Such low vapour pressure compositions are new to the art and cannot be anticipated based on the teaching of US 8,603,963 Bl, as it does require the use of at least 10 wt% of Low Vapour Pressure Potentiator compounds having a vapour pressure of at least about 0.2 mmHg at 25 °C.

Table 8: Low vapour pressure perfume composition for air freshener having

(*) Weighed-average vapour pressure at 20 °C

Example 6

In this example, the flash point of compositions according to the present disclosure has been measured and compared to those of compositions according to US 8,603,963 B1. Table 9: Flash point values of different mixtures of solvents and perfume fillers

As apparent from the above results, the use of solvents and fillers according to the present invention (Z2, Z4) provide compositions having flash points that are more in line with safety norms than those disclosed in the prior art (Z1, Z2).