GB2372450A - Air fresheners - Google Patents

Abstract

An air freshener comprising a free-standing, self-supporting gel composition. The composition may comprise a fragrance component in which a wax or a polymer is dissolved to form a gel. The fragrance component may be liquid hydrocarbon derived. The polymer may be a polyamide, or a styrene based polymer and may include a mineral oil component. The gel may be formed by mixing the fragrance component and the wax or polymer at elevated temperature and allowing the mixture to cool to a solid state. The gels of these compositions avoid syneresis (cracking and crazing over time), permit a high loading of fragrance component and retain their shape in use.

Description

Air Fresheners The present invention relates to an air freshener and in particular to substantially self-supporting solid compositions for releasing fragrance or perfume into the ambient atmosphere over a prolonged period of time.

Water based gels of carrageenans have been used to carry a fragrance which is slowly released into the atmosphere. A drawback of these systems is that they carry a relatively low amount of the fragrance, typically 5% by weight, and the product will craze or crack over time as the fragrance is released and the remaining material shrinks. Water based gels can also suffer from syneresis.

US 5 780 527 describes a system in which a polymer is cross-linked in the presence of a fragrance to form a three dimensional network which contains the fragrance. These systems can contain 70 to 90% by weight of the fragrance. The preferred polymers are polyolefins, particularly maleinised polybutadiene and maleinised polyisoprene cross-linked with an ethoxylated molecule. Such products are typically quite brittle and will shrink towards a central point. This, again, provides an unsightly appearance as the gel shrinks away from the sides of the container.

WO 00/24434 describes a system in which the fragrance releasing composition is carried in a narrow recess, apparently in order to provide a more even release rate over the effective life of the product. WO 00/24434 mentions the polyolefin systems referred to above, but also mentions alginates, carrageenans, and a variety of other polymers including polyamides, as the carrier matrix.

The present invention provides an air freshener comprising a composition which is self-supporting and which substantially retains its shape during the useful lifetime of the air freshener.

Such a composition may be formed by dissolving a wax or a polymer in a fragrance component, to form a self-supporting gel.

The amount of wax or polymer dissolved in the fragrance component is sufficient to form a gel like consistency which is selfsupporting.

We have found that by appropriate selection of the fragrance and the wax or polymer, it is possible to achieve a composition having a high fragrance content, 75% by weight or more. Such a high fragrance containing composition has improved performance characteristics such as giving greater impact in use or maintaining a more even release of fragrance over the product lifetime. More particularly, the composition shrinks one dimensionally as the fragrance evaporates, i. e. the product only shrinks away from the exposed surfaces. Thus, the composition may be shaped in a mould, and will retain the shape during use, when the fragrance evaporates.

If the dissolved wax or polymer content is too high, the available fragrance is reduced, and also the product is likely to be harder or more brittle and so may have less desirable shrinkage characteristics as the fragrance evaporates. The wax/polymer to fragrance ratio can be optimised by trial and error to meet the desired performance characteristics.

The composition preferably comprises more than about 50% by weight of fragrance component, more preferably more than about 70% by weight of fragrance component.

Very preferably the composition has from about 70% to about 90% by weight of fragrance component, more preferably from about 75% to about 85% by weight.

The fragrance component is a derivative of a liquid hydrocarbon. It may be a discrete chemical but more typically will be a complex mixture of volatile liquid ingredients of natural or synthetic origin. The fragrance component may be presented in an oily carrier liquid, typically 50% fragrance and 50% carrier. We prefer a fragrance having a high fragrance content, i. e. a little or no oily carrier, as this maximises the fragrance available for evaporation in use.

The polymer should be matched to the fragrance component to achieve the desired degree of solubility in the fragrance component. If there is a mismatch, the polymer may form a cloudy solution or gel: although this is not necessarily undesirable a clear product is usually preferred. More importantly, a higher polymer content, and hence a reduced fragrance content, may be required to achieve a sufficiently self supporting product.

Fragrance components with low polarity molecules are generally preferred. The fragrance should also have a relatively well defined working vapour pressure to provide the necessary evaporation rate at ambient temperatures.

Functional groups on the polymer structure will also affect the solubility of the polymer in the fragrance component.

Very preferably the, or the main, polymer component is a polyamide polymer. A particularly preferred polyamide is supplied as UNICLEAR 80V from Arizona Chemical Co. , USA, which is solid at room temperature.

Another preferred polymer is a styrene based polymer.

A wax, a high molecular weight hydrocarbon, may also be used to form the gel.

The formulation may include a variety of additives as commonly used in the art, including inert additives such as flowers or beads for aesthetic appearance, soluble additives such as colourants, or dispersed additives such as pearlescent particles.

A composition or formulation in accordance with the invention may be prepared by warming the polymer and the fragrance component with gentle mixing. At an elevated temperature, typically about 65OC, the polymer dissolves or disperses in the fragrance component. The warm solution is poured into containers or moulds. On cooling a single phase anhydrous gel may be formed. Depending on the vapour pressure characteristics of the fragrance, the mixing temperature should be kept as low as possible to avoid driving off too much of the fragrance components.

The mould is shaped to allow release of the cooled, solid composition.

The invention will be further described by way of example. All amounts are % by weight of the total composition.

EXAMPLE 1.

A lemon fragrance product was produced by warming UNICLEAR 80V (20% by weight), Solvent Yellow 93 colorant (0. 01%) (Clariant Sandoplast Yellow 3G) and Orange Turpene fragrance (balance %) to 65 C and mixing gently until a clear liquid was formed. The liquid was then poured into glass moulds and allowed to cool.

The cooled product had the following characteristics: 1. Shrinkage, due to fragrance evaporation, was one dimensional, i. e. the moulded product when exposed on one surface only became thinner with evaporation.

2. There was extended, slow release of fragrance.

3. Transparency was maintained through the effective life of the product-the polymer did not precipitate out.

4. The composition was self-supporting.

EXAMPLE 2 The following composition was prepared as in Example 1.

% W/W UNICLEAR 80 50 * Solvent Red 27 0.01 * Solvent Blue 35 0.01 French Lavender Oil Balance * Clariant Fat-Red 5B02 and Clariant Fat Blue B01.

The cooled product had properties similar to those described in Example 1.

EXAMPLES 3 TO 7 The following compositions were prepared as for Example 1. The percentage loss (evaporation) of the fragrance was then measured

Component/Ex 3 4 5 6 7 UNICLEAR 80V 25 25 25 25 25 Fragrance PF30551 75 " PF30549 75 "pu30550 75 PF30552 75 PF30548 75 Dye q. s q. s q. s q. s q. s All fragrances were supplied by Phoenix Fragrance.

UNICLEAR 80V was supplied by Arizona Chemical Co, USA and is a blend of 80% Polyamide, 20% Mineral Oil.

It is thought that the blending of the polyamide with the mineral oil, in

UNICLEAR 80V, may help to promote dissolution of the polymer in the fragrance. The polymer is a hard waxy polymer melting at 90oC, but it will 'melt'at about 65oC in the presence of the fragrance.

8 gm of the warm polymer/fragrance mix was poured into a glass mould having an exposed upper surface of 16cm2, giving a depth of about 5mm.

The weight loss equates to the amount of volatile fragrance components which evaporate. This was measured over time, and is presented in Figure 1.

It can be seen that after an initial period of one or two days, the rate of evaporation of fragrance is substantially linear for an extended period of

time. This provides for a product having substantially even performance for an extended period, four weeks or more.

Comparative Example 8

By way of comparison a similar test was performed on a commercial (. T) product, HAZE CRYSTAL AIR EXOTIC FRUITS manufactured by

Reckitt Benckiser which is believed to made in accordance with WO 00/24434. This shows a steeper initial fragrance loss, but then a much lower rate of fragrance evaporation after about 10 days.

EXAMPLE 9

zu Perfume PF30551, 65% by weight, was mixed with KRATON 1652 (ex Shell Chemicals) 65% by weight and heated to 100oC. The KRATON

polymer dissolved in the perfume and the mix was then poured into a shallow mould and allowed to cool to a gel. The gel was not as solid as Examples 1 to 7, but good fragrance release characteristics were obtained.

It will be appreciated that a fragrance with a flash point above the mixing temperature should be chosen.

() KRATON is a styrenic block co-polymer. Such polymers are produced by

polymerising styrene and then sequentially reacting with butadiene or isoprene to produce linear A-B-A, radial (A-B) n or di-block (A-B) polymers as required.

EXAMPLES 10 to 15 Waxes were also dissolved in a fragrance composition to produce a solid gel composition. An opaque product is formed with a hard gel. Some are subject to cracking as the perfume evaporates but good performance with prolonged perfume release over several weeks is obtained.

Ex. Wax % Wax % Observations Perfume 7 10 Hydrogenated 50 50 Brittle and cracks Castor Oil'on shrinkage 11 Polyglyceryl-3 28 72 Brittle and cracks Beeswax2 on shrinkage 12 Beeswax3 43 57 No cracking 13 Microcrystalline 18. 5 81. 5 No cracking Wax4 14 Paraffin Wax5 65 No cracking 15 CamaubaWax46. 453. 4No cracking 1. Liowax PM80 from Miracema-Nuodex 2. Cera Bellina from Jan Dekker 3. White Beeswax BP from Poth Hille 4. Microcrystalline Wax 3749 from Poth Hille 5. Paraffin Wax 125/130 from Astor Stag 6. Camauba Wax from Stanley Black 7. Orange Turpenes Figure 2 shows a plan view of an air freshener product containing a composition for forming an air freshener in accordance with the invention.

Figure 3 is a cross-section on line III-III of Figure 2 ; Figure 4 is similar to Figure 3, but showing the product part used; Figure 5 shows a plan view of a prior art product, and Figure 6 shows an air freshener product forming a first embodiment of the invention.

Figure 7 shows an air freshener product forming a second embodiment of the invention; Figure 2 shows a plan view of an air freshener comprising a composition 2 prepared in accordance with Example 3 above, and contained in a glass mould 4. The composition 2 fills channels 3 provided in a major surface 5 of the mould 4. As seen in Figure 3, the channels 3 are initially filled with the composition 2. The cross-section of Figure 4 shows the product after exposure to the ambient atmosphere for about three weeks. Fragrance has evaporated, causing apparent shrinkage of the remaining composition into the channels 3. It can be seen that the composition shrinks onedimensionally, that is it continues to fill the channels 3 across their full width. Hence the plan view is still as seen in Figure 2. If the product is left until substantially all the fragrance is evaporated, the polymer component will remain in the bottom of the channels 3.

Figure 5 shows a plan view of the composition of comparative example 8 after about three weeks. It can be seen that the remaining composition has shrunk away from the sides of the channels 3, forming gaps 5 and giving a quite different visual appearance, which is uncontrolled during the life of the product. Figure 6 shows an embodiment of the invention. A shape 10, in this case a rabbit shape about 5 cm high and 1.5 cm thick is formed by casting the molten composition of Example 3 in a mould. The mould may be coated with a release agent to allow release of the shape, but the release agent should not contaminate the surface of the finished product, or otherwise inhibit evaporation of the fragrance component. The shape is selfsupporting. In practice it may be formed on a base 12 to protect any supporting surface from the oils etc. in the composition. Components having little or no skin hazards are preferred because of the likelihood of handling by the user.

Figure 7 shows a simple cube shape 10, formed with the composition of Example 3. The initial cube has a side of about 10 cm, and a fragrance content of about 75%. After loss of the fragrance, the cube will have shrunk to about 25% of its volume, i. e. about 6 cm on a side.

Claims (12)

1. CLAIMS: 1. An air freshener comprising a free-standing gel composition which is self-supporting.
2. 2. An air freshener as claimed in claim 1, wherein the gel composition comprises a wax or a polymer dissolved in a fragrance component.
3. 3. An air freshener as claimed in claim 1 or 2, wherein the polymer is a polyamide.
4. 4. An air freshener as claimed in claim 3, wherein the polymer includes a mineral oil component.
5. 5. An air freshener as claimed in claim 1 or 2, wherein the polymer is a styrene based polymer.
6. 6. An air freshener as claimed in any one of claims 1 to 4, having at least 50% by weight of fragrance component.
7. 7. An air freshener as claimed in claim 6, having at least about 70% by weight of fragrance component.
8. 8. An air freshener as claimed in claim 7, having from 70 to 90% by weight of fragrance component.
9. 9. An air freshener as claimed in claim 8, having from 75 to 85% by weight of fragrance component.
10. 10. A method of producing an air freshener composition, the method comprising mixing a fragrance component and a polymer component at elevated temperature, pouring the composition into a mould, allowing the mixture to cool to a gel like solid and removing the mixture from the mould.
11. 11. A method as claimed in claim 10, wherein the polymer is a solid at room temperature (20 to 25oC).
12. 12. A method as claimed in claim 10 or 11, wherein the fragrance is a liquid derivative of hydrocarbon at room temperature.