GB2349572A

GB2349572A - Fragrance compositions

Info

Publication number: GB2349572A
Application number: GB9927091A
Authority: GB
Inventors: John Martin Behan; Keith Douglas Perring; Pieter Cornelis Traas
Original assignee: Quest International BV
Current assignee: Givaudan Nederland Services BV
Priority date: 1998-11-18
Filing date: 1999-11-17
Publication date: 2000-11-08
Also published as: GB9825160D0; GB9927091D0

Abstract

A fragrance composition has a solubility parameter (Hildebrand parameter) in the range 16.5 to 22.5 and can be used to supply desired odour characteristics without degrading an associated polymer film.

Description

Title: Improvements in or relating to Fragrance Compositions Field of the Invention This invention relates to fragrance compositions, particularly fragrance compositions intended to be heated, and concerns a fragrance composition, particulaily but not exclusively a heatable fragrance composition, a fragrance product for use with a heater, and a fragrance heater. The term"fragrance composition"is used herein to mean a mixture of fragrance materials, possibly mixed with or dissolved in a suitable solvent or mixture of solvents and/or possibly added to a solid substrate, which exhibits odour properties (usually but not necessarily generally considered pleasant or attractive), and the term"heatable fragrance composition"is used herein to mean a fragrance composition that exhibits odour properties at least when heated, typically to a temperature of at least about 60 C.

Background of the Invention The use of heat to cause a fragranced substrate to emit its fragrance by a process of evaporation is well known, and a wide variety of devices are available to supply heat to such fragranced substrates. Heating devices come in many shapes and sizes and may be electrically operated (eg heated elements in devices intended to be plugged into a mains electricity supply (referred to as"plug-ins") or arrangements using heat from electric light bulbs) or they may use the heat of naked flames (eg scented candles, incense burners or aromatherapy oil burners) or any other source of heat.

Some heated air-fresheners of the plug-in type rely on a polymeric film, usually of polyethylene, to regulate the diffusion of vaporised material from a concentrate in a container following heating. Unfortunately, polymeric films have a tendency to degrade as fragrance is emitted through them. This degradation causes a reduction in the integrity of the system and a loss of uniform emission rate through the film. The overall effect is to reduce the useful life of the product.

Traditionally, perfumes for use in heated devices are provided dissolved in a suitable solvent, with particulate silica (eg Aerosil-Aerosil is a Trade Mark) also being included when it is required to increase the viscosity of the overall composition. This final composition may be placed within a container having a heatable surface, with the container being sealed with a polymeric film. The container is then introduced to the heating device in such a way that the polymeric film is furthest from the heat source and the heatable surface is in contact with the heat source. On applying heat, the fragrance composition produces an odorous vapour which moves through the polymeric film and escapes to the atmosphere to provide the desired effect.

Typical concentrates and containers are described in German Patent DE 4301912 (Globol).

The concentrate described therein is a stearate gel comprising 0 to 10% by weight of highly dispersed silicic acid, at least 5% by weight of sodium stearate, 0 to 20% by weight of isopropanol and 85 to 95 % by weight of perfume. The container is described therein as comprising 0 to 10% by weight polyvinyl pyrrolidone, 0 to 10% by weight natural resin acid esterified with polyether alcohol and further additives.

Heated air-fresheners are described in for example US 5574821 (Babasade), US 5647052 (Reckitt & Colman), EP 696457 (Steinel) and EP 451331 (Globol).

Prior art as exemplified by EP 511853 (Reckitt & Colman) has been concerned with controlling the release of active materials from heated air fresheners by varying the heat supplied to fragrance-carrying cartridge and involving temperatures sensitive semipermeable membranes.

Examples of slow release of fragrances in the prior art include US 4184099 (IFF) which refers to the use of a fatty polyamide of molecular weight 9000 to 12000 to control the release of fragrance from the fatty polyamide when it is heated; EP 328370 (Crammond) which controls the release of fragrance adjacent to a heat source by incorporating the fragrance in, and evaporating it from, a particulate plastic material such as granules or beads of polyethylene, polypropylene or polyvinyl chloride.

Summary of the Invention According to one aspect of the present invention there is provided a fragrance composition, particularly a heatable fragrance composition, having a solubility parameter in the range 16.5 to 22.5.

The solubility parameter of the composition is preferably in the range 18.5 to 20.5.

The term"solubility parameter"refers to the Hildebrand parameter, which is a measure of cohesion well known in physical chemistry. A full description may be found in the text "Solubility Parameters and other Cohesion Parameters"by A F Barton, published by CRC Press (1983). Solubility parameter may be determined from equation (1) below, but is more conveniently estimated by a variety of group additive methods. The method due to Hoy (see section 6.4 in the above reference of Barton) has been used in this invention.

Equation (1) Solubility Parameter = [ (dH-RT)/V]' where : dH = molar enthalpy of vaporisation V = molar volume R = the gas constant T = temperature Solubility parameter was originally developed as a means of explaining or predicting the likely solubility of liquids in one another, but has since been used extensively as a broad guide to the compatibility of materials with plastics. Extensive descriptions of such applications are given in the aforementioned Barton text along with descriptions of methodologies for determining"effective"solubility parameters for materials whose solubility parameters cannot strictly be calculated by equation (1), eg solids with no known vaporisation enthalpy.

In general, two materials will show the greatest interaction when they are characterised by similar solubility parameters. For example, polyethylene has a solubility parameter which normally falls within the range 16.0 to 17.0, depending upon morphology and manufacturing history and is found to be readily attacked by hydrophobic materials with solubility parameters close to this range (eg 16 to 18). It is not known, however, to select fragrances on the basis of solubility parameters to ensure compatibility with polyalkylene membranes, particularly at elevated temperatures (such as 60 to 80 C or higher), and yet interact sufficiently to allow a useful fragrance transmission rate through the membrane.

Without being bound by theory, it is thought that the structure of the preferred fragrance compositions in accordance with the invention, to be discussed below, is such that a polymeric membrane is partially'opened'in use by the presence of small percentages of components with low solubility parameters.

The fragrance composition is typically, but not necessarily, intended to be used by being heated, eg in known manner as discussed above. Such compositions generally have a useful life, producing a discernible odour on heating, for a period of about 50 hours or so in typical cases. Alternatively, the composition may be intended to be used at ambient temperature, producing a discernible odour at least at low levels over an extended period of time, eg several weeks or months. In both cases, the composition may have an associated polymeric film, typically of polyalkylene eg polyethylene, through which the odour passes from the composition in use. The fragrance composition is typically located in a suitable container, eg of generally cup-shaped form, of heat-proof material if appropriate, sealed with polymeric film.

By controlling the solubility parameter of a fragrance composition, we are able to provide compositions which supply desired odour characteristics eg on heating whilst not degrading an associated polymeric film which controls their release into the environment.

The present invention can thus provide a heatable fragrance composition which when used, typically by heating, in the presence of an associated polymeric film, eg of polyalkylene such as polyethylene, will produce less degradation of the film and produce a more regular odour emission rate and odour profile in use compared with conventional fragrances. The fragrance composition can also be more compatible with packaging and eg does not discolour the casing of a heating device.

The fragrance composition typically comprises a mixture of ingredients each having its own solubility parameter, with the mixture having a solubility parameter within the range 16.5 to 22. 5 (as a weight-averaged mean).

The ingredients of the fragrance composition may be selected from suitable known fragrance materials, including natural products such as extracts, essential oils, absolutes, resinoids, resins, concretes etc., and also synthetic materials such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, esters, acetals, ketals, nitriles, etc., including saturated and unsaturated compounds, aliphatic, carbocyclic, and heterocyclic compounds.

Such fragrance materials are mentioned, for example, in S. Arctander, Perfume and Flavor Chemicals (Montclair, N. J., 1969), in S. Arctander, Perfume and Flavor Materials of Natural Origin (Elizabeth, N. J., 1960) and in"Flavor and Fragrance Materials-1991", Allured Publishing Co. Wheaton, III. USA.

The ingredients of the fragrance composition may include one or more solvents, eg selected from those known for use in fragrance compositions including ethanol, isopropanol, diethyleneglycol monoethyl ether, dipropylene glycol, diethyl phthalate, triethyl citrate, isopropyl myristate, etc.

The nature and amounts of the ingredients of the fragrance composition must be selected such that the weight-averaged mean solubility parameter of the composition is within the specified range of 16.5 to 22.5.

Solid materials, generally in particulate, granular or block form, may optionally be added to the heatable fragrance composition, eg in the form of particulate silica such as Aerosil or particulate plastics material such as granules or beads of polyethylene, polypropylene or polyvinyl chloride which act to absorb the liquid ingredients. Solid material is added to achieve desired product consistency. The final form of the product may be that of a gel with no discernible particles.

It appears that by careful selection of ingredients of the fragrances composition based on their solubility parameters, the pore sizes of polymeric films used with fragrance compositions, eg in fragrance heaters such as heated air-fresheners, can be made to increase gradually during the life of the fragrance composition. Therefore, as the composition ages with use, materials of lower volatility are allowed to pass through the polymeric film more easily and so are emitted from the composition.

Such preferred fragrance compositions thus seemingly act so that the polymeric film is partially'opened'by the presence of small percentages of components having low solubility parameters.

This effect is achieved by including in the fragrance composition a comparatively small proportion, typically up to about 20% by weight, eg at least about 5%, 10% or 15% by weight, of fragrance ingredients having a solubility parameter of less than about 18, preferably less than about 17, more preferably less than about 16, with the composition nevertheless having an overall solubility parameter (as a weight-averaged mean) within the range 16.5 to 22.5. Such low solubility parameter ingredients are of low or very low polarity, and in the extreme case are non-polar materials. Use of such a composition causes the pore sizes of polymeric film to increase slowly during the emanation of these fragrances such that low volatile ingredients are allowed to evaporate through the film in the latter part of the life of a fragrance composition. As discussed above, this effect is thought to be due to the low solubility parameter (and low polarity) ingredients causing controlled, limited degradation of an associated polymeric film, resulting in gradual increase in the size of pores in the film, permitting progressively and gradually increasing emission through the film of fragrance materials of lower volatility during use of the composition.

This invention allows fragrances to be developed using low volatile materials, which provides the ability tG maximise fragrance capability and effect of (heated) fragrance compositions eg air freshener products throughout their use.

The fragrance composition may to advantage include a comparatively small proportion, eg up to about 10% by weight, of Isopar (Isopar is a Trade Mark of Exxon and comprises a mixture of various hydrocarbons). Isopar is used as a solvent in the fragrance industry, and may also be used to increase the content of non-polar materials (having a solubility parameter of about 16 or less) in the composition.

The fragrance composition preferably contains a comparatively small proportion, eg up to about 10% by weight, of terpenoids. The term"terpenoid"is used herein to mean hydrocarbons (ie composed of carbon and hydrogen only) which can be considered to be derived from the 5-carbon compound"isoprene" (2-methylbuta-1, 3-diene). Such hydrocarbons are used extensively in perfumes, directly or indirectly via essential oils.

Such materials all are very non-polar and so are useful, in limited amounts, as low solubility parameter ingredients, as discussed above.

The fragrance composition preferably includes a relatively large proportion, eg at least 30% by weight preferably at least 50% by weight, of ingredients having similar solubility parameters (eg within the range 18.5 to 19.5), ie having uniform solubility parameters.

This is conveniently achieved by use of one or more suitable esters as ingredients of the composition.

The fragrance composition preferably includes one or more antismoke aldehydes, typically in an amount of at least 5% by weight, preferably at least 7.5% by weight and most preferably greater than 10% by weight. Typical antismoke aldehydes are described in WO 97/15186 (Quest), and include cyclamen aldehyde and heliotropin.

The ingredients of the fragrance composition are preferably compatible with and nonreactive with respect to particulate silica, eg in the form of Aerosil.

In cases where the fragrance composition is intended to be used by heating, the composition preferably contains at least 60% by weight of materials which are stable at elevated temperature, eg about 70 C.

The fragrance composition may be in the form of an insecticidal composition, bactericidal composition or animal, eg insect, repellent composition, including appropriate active ingredients in known manner, or may simply be an odourant composition that produces an odour (pleasant or otherwise).

In another aspect, the invention provides a fragrance product, comprising a fragrance composition in accordance with the invention, and an associated polymeric film through which odour from the composition passes in use.

In a further aspect, the present invention provides a fragrance product for use with a heater, comprising a heatable fragrance composition in accordance with the invention, and an associated polymeric film through which odour from the composition passes in use.

The product may be of generally conventional construction, eg as described in the prior art noted above, and typically comprises a container housing the fragrance composition, and sealed with the polymeric film.

The polymeric film is typically of polyalkylene, eg polyethylene.

In another aspect, the invention provides a fragrance heater, such as a heated air freshener, comprising a fragrance product in accordance with the invention The heater may be a heated air freshener as described in the prior art discussed above.

In preferred embodiments at least, the invention thus concerns fragrance compositions which, when they are used eg in heated air fresheners, do not degrade associated polymeric film, do not discolour the casing of the heating device and do allow the fragrance composition to be evaporated evenly through the polymeric film, such that its effect and perception is maintained until the composition is effectively totally evaporated.

The invention will be further described, by way of illustration, in the following Examples of fragrance compositions in accordance with the invention.

Example 1 A fragrance composition in accordance with the invention was prepared by mixing the following ingredients.

Ingredient sp w/w% Allyl amyl glycolate 17.9 1.51 Allyl heptanoate 17.5 1.72 Benzyl acetate 20.2 3.01 Borneol 21.5 1.94 Camphor 18. 5 2.80 Cineole 17.6 1.40 cis-3-Hexenol 21.7 0.54 Citronellol 19. 4 6.67 Cyclamen aldehyde 18.9 1.51 Decanal 17.6 0.65 Diethyl phthalate (solvent) 20.6 4.09 Dihydromyrcenol 18.9 6.99 dodecanal 17.5 0.86 Dowanol DPM (Dow) (solvent) 23.0 6.24 Extralide (Q) 18.2 1.18 Florocyclene (Q) 18.6 1.61 Geraniol 20.2 2.26 Heliotropin 19.3 0.75 Iso Cyclo Vert (Q) 18.2 0.54 Isobornyl acetate 17.0 8.06 Jasmacyclene (Q) 19.6 5.81 Lavandin oil 18.6 * 9.03 Lemongrass oil 18.6 * 1.29 Ligustral (Q) 18.7 2.80 Limonene 16.5 3.12 Linalol 19.8 5.59 Linalyl acetate 16.8 1.29 Lixetone (Q) 18.4 1.29 Manzanate (Q) 17.1 0.32 Methyl hexyl ketone 17.7 0.75 Methyl nonyl acetaldehyde 17.1 0.65 Nopyl acetate 18.6 2.58 Octanal 17. 9 0.54 Phenylacetaldehyde dimethyl acetal 19.0 1.40 Rosemary oil 17.6 * 1.18 Styrallyl acetate 19.2 0.75 Terpineol 20.2 4.73 Terpinyl acetate 17.6 2.58 Total 100.00 Weight-averaged mean SP 19.1 SP = solubility parameter (Hoy estimate) in MPa' * = estimate (typical composition) The materials marked with a Q are identified by Trade Marks and are available from Quest International.

The material marked Dow is identified by a Trade Mark and is available from Dow Chemical.

All of the materials are compatible with and non-reactive which respect to relatively inert particulate silica materials such as Aerosil.

The"terpenoid"content of the composition is estimated to be about 4 to 5% by weight, being provided directly by limonene and indirectly by rosemary oil, lavandin oil and lemongrass oil.

The fragrance composition of Example 1 was tested as plug-in product by placing a portion of the composition in a container and sealing the container with polyalkylene film in known manner. The container was used with a conventional plug-in heater element in known manner. The composition gave generally good performance, providing fairly uniform fragrance release during extended use, over a period of about 50 hours, with little degradation of the film occurring.

Example 2 A further fragrance composition in accordance with the invention was prepared by mixing the following ingredients: Fragrance from Example 1 93 wlw% Isopar L (solvent) 7 w/w% The resulting mixture had a weight-averaged mean SP of 18.8.

The fragrance composition of Example 2 was tested in the same manner as that of Example 1 and showed generally similar good performance, with slightly improved performance towards the later stages of use, in that the overall character of the fragrance was perceived as being maintained for longer. This is thought to be due to the effect of the non-polar (very low solubility parameter) ingredients of Isopar L in gradually increasing the size of pores in the associated polyalkylene film in use, as discussed above.

Claims

Claims 1. A fragrance composition having a solubility parameter in the range 16.5 to 22.5.
2. A fragrance composition according to claim 1, having a solubility parameter in the range 18.5 to 20.5.
3. A fragrance composition according to claim 1 or 2, wherein at least about 5% by weight of the ingredients have a solubility parameter of less than about 18, preferably less than about 17, more preferably less than about 16.
4. A fragrance composition according to claim 3, wherein at least about 10% of the ingredients have a solubility parameter of less than about 18, preferably less than about 17, more preferably less than about 16.
5. A fragrance composition according to claim 4, wherein at least about 15% by weight of the ingredients have a solubility parameter of less than about 18, preferably less than about 17, more preferably less than about 16.
6. A fragrance composition according to claim 3,4 or 5, wherein not more than about 20% by weight of the ingredients have a solubility parameter of less than about 18, preferably less than about 17, more preferably less than about 16.
7. A fragrance composition according to any one of the preceding claims, comprising up to about 10% by weight of Isopar (Isopar is a Trade Mark).
8. A fragrance composition according to any one of the preceding claims, comprising up to about 10% by weight of terpenoids.
9. A fragrance composition according to any one of the preceding claims, comprising at least 30% by weight of ingredients having similar solubility parameters.
10. A fragrance composition according to any one of the preceding claims, including one or more antismoke aldehydes.
11. A fragrance composition according to any one of the preceding claims, wherein the composition is compatible with and non-reactive with respect to particulate silica.
12. A fragrance composition according to any one of the preceding claims, wherein at least 60% by weight of the ingredients are stable at about 70 C.
13. A fragrance composition according to any one of the preceding claims, further comprising a polymeric film through which odour from the composition passes in use.
14. A fragrance composition according to claim 13, further comprising a container within which the fragrance composition is located, the container being sealed with the polymeric film.
15. A fragrance composition to claim 13 or 14, wherein the polymeric film comprises polyalkylene.
16. A fragrance composition according to claim 15, wherein the polymeric film comprises polyethylene.
17. A fragrance product comprising a fragrance composition in accordance with any one of the preceding claims, and an associated polymeric film through which odour from the composition passes in use.
18. A fragrance product for use with a heater, comprising a fragrance composition in accordance with any one of claims 1 to 16, and an associated polymeric film through which odour from the composition passes in use.
19. A product according to claim 17 or 18, comprising a container housing the fragrance composition and sealed with the polymeric film.
20. A product according to claim 17,18 or 19, wherein the polymeric film comprises polyalkylene.
21. A product according to claim 20, wherein the polymeric film comprises polyethylene.
22. A fragrance heater comprising a product according to any one of claims 17 to 21.