Flexible fragranced products

Abstract

A fragranced product, such as a urinal screen, which comprises an ethylene vinyl acetate (EVA) mixture and at least 7.5% by weight of fragrance oil, in which the EVA mixture comprises at least 7.5% by

Description

5 FIELD OF THE INVENTION The present invention relates to flexible fragranced products, particularly but not 10 exclusively to urinal screens and air fresheners. BACKGROUND ART Fragranced products are employed to release a fragrance overtime, often a protracted period of weeks, so as to freshen the surrounding air with a pleasant scent for that period, and sometimes to mask unpleasant odours also. Many fragranced products comprise a matrix 15 material which carries the fragrance material, and the matrix material is composed, and shaped and configured, so as to conduct the fragrance material through the matrix material towards an outer surface and to release the fragrance effectively from that outer surface at a rate effective to freshen surrounding air, whilst being capable of containing sufficient fragrance material to maintain the rate of release of fragrance to freshen surrounding air 20 effectively for the desired period of time. Depending on the particular application, fragranced products may be compact, with a low surface area to volume ratio, or they may have a high surface area to volume ratio; one example of the latter type of fragranced product is where it is in the form of a sheet. It is often advantageous for high surface area to volume ratio fragranced products to be flexible: for example, to be able to conform to the shape of a 25 surface to which the product is to be applied, or to be fitted within a container or other confined space (such as by being loosely rolled up) while still retaining the ability to dispense fragrance. One sort of flexible fragranced product is a urinal screen; urinal screens are widely used to prevent solid objects or debris from being flushed down the urinal drain, whilst 26 02 24 freshening the air in the vicinity of the urinal. The matrix material in air fresheners may be made in a thin flat shape to be rolled up inside a container so as to maintain a high surface area to volume ratio and allow a high rate of fragrance release, so that such fragranced products are flexible; alternatively, the matrix material may be formed in a shape which is 5 inherently less flexible, such as a sphere, cube or the like, even though the matrix material itself is flexible. Many flexible fragranced products are made of Ethylene-Vinyl Acetate plastic (EVA) which is impregnated with fragrance materials and then injection moulded into the desired shape. EVA is an elastomeric polymer that produces materials which are "rubber-like" in 10 softness and flexibility. The material has good clarity / transparency and gloss, low-temperature toughness, stress-crack resistance, hot-melt adhesive waterproof properties, and resistance to chemicals and UV radiation, and a high friction coefficient. There are many examples of mixing fragrance with EVA and the injection moulding of EVA, or mixtures of EVA with other plastics, to make urinal screens. This method has inherent 15 problems in that only certain fragrance ingredients are readily absorbed into the EVA, and many of these fragrance components absorbed into the EVA are locked into the product, meaning much of the fragrance can't evaporate in the service life of the product and is wasted when the product has reached its end of life and is discarded. Most EVA products contract when the contained fragrance begins to evaporate, and this contraction reduces the surface 20 area available for the evaporation of the fragrance to occur. The contraction continues until an equilibrium is reached, when the fragrance still inside the product does not have sufficient vapor pressure to migrate through the EVA plastic as it becomes denser during the evaporation of the fragrance. Thus, eventually much fragrance is trapped inside the product. Typically, in the average usage life of these urinal screens, approximately 30 days, 50 to 70% of the 25 fragrance can evaporate with another 10-20% taking months longer. In this way the product is inefficient as they are discarded at 30 days while still containing 30 to 50% of the fragrance oil. It would be desirable to formulate a fragranced product which does not trap fragrance within the EVA, and which allows more of the fragrance oil to be released. 26 02 24 SUMMARY OF THE INVENTION The present invention is predicated on utilising a new ingredient which aids the absorption and release of fragrance oil material. The present invention therefore provides a fragranced product comprising an EVA mixture and at least 7.5% by weight of fragrance oil, 5 in which the EVA mixture comprises at least 62.5% by weight EVA and at least 7.5% by weight of an organic starch component. Such a composition has been shown to allow as much as 90% of the fragrance oil to evaporate during the useful life of a urinal screen. Whilst this is a significant improvement over conventional products in itself, we have discovered that products in accordance with the 10 invention have several further, unexpected benefits. Firstly, it would be expected that there would be an environmental benefit in replacing some plastic in the final product (i.e. the EVA) with an organic starch material, but we found that it was possible to create products with less material overall compared to conventional ones because the material of products in accordance with the invention are more structurally supportive, which adds to the 15 environmental benefit of the invention. Secondly, the starch component more readily absorbs polar fragrance chemicals than does EVA, so that products in accordance with the invention are capable of absorbing more polar fragrance chemicals than products which are wholly EVA; this allows a greater variety of fragrances to be released by the products. Thirdly, the EVA mixture will also absorb more hydrocarbon and non-polar fragrance materials than the starch 20 component, meaning that the fragrance contained in the product can be more varied. The benefit is that it allows the fragrance odour release to change over time avoiding "nose blindness" where a person becomes used to the fragrance. For example, a polar fragrance chemical to promote the scent of a rose, such as Phenyl ethyl Alcohol, would be concentrated in the starch component, while the EVA would more readily contain a non-polar fragrance 25 chemical to promote citrus odour such as limonene; other non-polar materials commonly used in fragranced products are pinene, limonene, cedrene, farnesene, galaxolide and dihydroambrettolide. Other polar chemicals which may be used are geraniol, cinnamyl alcohol, benzoic acid, cinnamic aldehyde and anisole. Mixtures of non-polar chemicals and / or nonpolar chemicals can be used to allow the fragrance to begin with one type of odour and end 30 with another: going from floral to citrus over time, for example. When a product in accordance with the invention is manufactured by injection moulding, it is at its largest volume and size. Once the product is put into service and exposed to the environment, so that the fragrance 26 02 24 oil it contains can begin to evaporate, then the product will begin to shrink (as will conventional fragranced products); however, the shrinkage with the product is not uniform (which is the case with typical EVA products) because the starch component does not shrink, and many benefits come from this feature. 5 Shrinkage of products in accordance with the invention causes progressively more of the starch component to be exposed to the environment and these starch particles and structures allow the fragrance inside the EVA matrix to continuously find their way to the surface of the product and evaporate. This increases the amount of fragrance that can be evaporated in the useful life of the product. Additionally, as the starch component reduces the 10 product shrinkage significantly (up to 30% less) than the known fragranced, EVA-only products, the surface area of the product remains greater. This larger surface area allows greater evaporation of fragrance from the product. Together these advantages in mobility of the fragrance and the surface area of the product allow as much as 90% of the fragrance oil to be evaporated during the useful life of the product, meaning that the products are more 15 efficient at allowing evaporation of the fragrance contained within the product. In addition to the improved efficiency of the fragrance release in a thin-walled product, there are benefits for thicker products. Typically, fragranced EVA products are limited to a maximum thickness of about 5 mm, because the fragrance in such a thick part can become trapped and the evaporation efficiency of the product deceases sharply above 3mm thickness. 20 Products in accordance with the invention continue to function with a good efficiency when thicker than 5mm because the starch component transports fragrance chemicals to the surface of a thick product in the same way that a wick functions. Thus, the fragranced products can be made in thicker designs that remain efficient for fragrance oil evaporative release. The organic starch component may comprise between 7.5% and 37.5% by weight 25 (with the EVA forming the remaining 92.5% to 62.5% of the EVA mixture), and is preferred to be 30% by weight. The fragrance oil may comprise between 7.5% and 40% by weight of the product (with the remaining 92.5% to 60% being the EVA mixture), and is preferably about 30% by weight. The organic starch component may comprise at least 30% by weight powdered starch, 30 and up to 70% by weight in total of one or more of rice husk, pulverised rice and cellulose fibres. The addition of fibrous material adds structure to the final product, and assists in 26 02 24 wicking fragrance oil through the product to the surface for evaporation. Preferably the organic starch powder is powdered cassava root, or tapioca. The EVA may be manufactured from ethylene which is derived from fossil fuel or, more environmentally advantageously, derived from sugar cane or other biological source material. 5 The fragrance oil may comprise a non-polar fragrance and / or a polar fragrance; where there is a mixture of these, they can range between 5% : 95% and 95% : 5% by weight, and are preferably 75% non-polar and 25% polar. The invention extends to methods of manufacturing fragranced products as described above, the method comprising the steps of: 10 a) making a mixture of organic starch component and EVA where the organic starch comprises at least 7.5% by weight of the mixture and the mixture comprises at least 62.5% by weight EVA, b) heating the mixture above 35° C, c) agitating the heated mixture while adding at least 7.5% by weight of a non-15 polar fragrance oil into the agitated mixture, d) when the non-polar fragrance oil has been absorbed into the mixture, ceasing the agitation and cooling the mixture to room temperature, and e) in a subsequent stage, heating the mixture and moulding it into a desired shape. 20 It will be understood that step a) of the above method may be modified so as to create the mixtures as described above in relation to the EVA mixture and the starch component, promoting the same advantages. Polar fragrance materials may be added during step a), and / or during step c). The mixture at step a) may be created by metering the materials forming the organic starch component into an extruder with the EVA. The heat at step b) may 25 range between 35°C and 50°C. The heating of step b) and the agitation of step c) may be carried out by putting the mixture into a sealed, rotatable container where the mixture is heated and rotated / tumbled as liquid fragrance is injected into the container. The polar and non-polar fragrance materials are added at steps a) and c) in the amounts described above in relation to the products. Steps b) and c) may alternatively be carried out in an extrusion 26 02 24 process, but this is less preferable than tumbling due to cost and unwanted evaporation of the fragrance oil caused by repeated cycles of high temperature of the material in the extrusion process. DETAILED DESCRIPTION OF THE EMBODIMENTS 5 The method of manufacturing products in accordance with the invention will now be described by way of example. 1. EVA is procured (either EVA where the ethylene derived from fossil fuel or EVA which is made using ethylene derived from sugar cane). 2. Casava root is harvested, peeled and grated into water. The water is then separated 10 and the material allowed to dry, and then it is pulverized. a. Additionally pulverized rice husk can be added. b. Additionally pulverized rice can be added. c. Additionally other starch can be added d. Additionally other cellulose fibres can be added 15 3. The material from 2. above is metered into an extruder along with the EVA from 1. 4. The material from 3. above is then put into a sealed rotating container where it is heated to between 35 and 50 Celsius and liquid fragrance is injected into the container while the heated material is being tumbled. This fragrance is designed specifically to be absorbed into this material with the amounts of polar and non-polar materials described 20 above. 5. After the predetermined amount of fragrance has been absorbed, the material is cooled to room temperature. The absorption of the fragrance typically takes between about 2 hours and about 8 hours at 35°C and at an agitation rate of 2 to 10 rpm of the tumbler. 6. The mixture from 5. above is then mixed appropriately with pigment (colour additive) 25 and sent to the injection moulding plant to be moulded into shape, e.g. a urinal screen. 7. In the injection moulding equipment, the mixture from 6. above is heated to a state where it will flow easily into the moulds and injected to produce the formed final products. The mixture flows into the mould between 95°C and 150°C and varies based upon the equipment type and the concentration of fragrance. Ideally, the mixture is 5 heated to 110°C to flow easily into the mould and be moulded. It will of course be understood that many variations may be made to the abovedescribed embodiments without departing from the scope of the present invention. For example, the invention has been described in relation to urinal screens, which are usually generally thin and flat and, because of the rubber-like character of EVA, are therefore flexible; 10 however, EVA compositions in accordance with the invention can be formed into any shape, some of which may not be susceptible to flexing, and therefore products in accordance with the invention need not necessarily be flexible. Where different variations or alternative arrangements are described above, it should be understood that embodiments of the invention may incorporate such variations and / or 15 alternatives in any suitable combination. 26 02 24 26 02 24

Claims

1. A fragranced product comprising an EVA mixture and at least 7.5% by weight of fragrance oil, in which the EVA mixture comprises at least 62.5% by weight EVA and at least 7.5% by weight of an organic starch component.5 2. A fragranced product according to Claim 1, in which the amount of organic starchcomponent is at least 30% by weight of the EVA mixture.

3. A fragranced product according to Claim 1 or Claim 2, in which the amount of fragrance oil is at least 30% by weight.

4. A fragranced product according to Claim 1, 2 or 3, in which the fragrance oil comprises 10 a polar fragrance.

5. A fragranced product according to any of Claims 1 to 4, in which the organic starch component comprises at least 30% by weight powdered starch, and up to 70% by weight in total of one or more of rice husk, pulverised rice and cellulose fibres.

6. A fragranced product according to any preceding claim, in which the fragrance oil 15 comprises a non-polar fragrance.

7. A urinal screen made from a fragranced product according to any preceding claim.

8. A method of manufacturing a fragranced product according to any of Claims 1 to 7, comprising the steps ofa) making a mixture of organic starch component and EVA where the organic20 starch component comprises at least 7.5% by weight of the mixture and themixture comprises at least 62.5% by weight EVA,b) heating the mixture above 35° C,c) agitating the heated mixture while adding at least 7.5% by weight of a nonpolar fragrance oil into the agitated mixture,25 d) when the non-polar fragrance oil has been absorbed into the mixture, ceasingthe agitation and cooling the mixture to room temperature, ande) in a subsequent stage, heating the mixture and moulding it into a desired shape.

9. A method according to Claim 8, comprising introducing polar fragrance material(s) during step a), and / or during step c).5 10. A method according to Claim 8 or Claim 9, in which steps b) and c) are carried out byputting the mixture into a sealed, rotatable container where the mixture is heated and rotated / tumbled as liquid fragrance is injected into the container11. A method according to Claim 8, 9 or 10, in which in which the heating in step e) is carried out at 110°C.26 02 24