AU636863B2 - Fragranced articles - Google Patents

Description

FRAGRANCED ARTICLES

The present invention relates to fragranced articles, and finds particular application in articles designed to provide a controlled release of fragrance over time.

It is known that it is possible to incorporate a fragrance into plastics materials, the fragrance subsequently being released over a period of time. Such products may be used in a domestic environment to provide a pleasant smell where the air may otherwise be stale. However, the use of plastics materials in fragranced articles can lead to difficulties in certain environments, for instance where the environmental conditions fluctuate widely or would subject the article to high temperatures. The articles can be rendered unpredictable in behaviour, for instance in the manner of releasing the fragrance, or in their physical characteristics such as hardness or crystallinity. - 2 -

According to the present invention, there is provided a fragranced article for use at temperatures above room temperature, the article comprising a copolymer of ethylene and vinyl acetate, the proportion of vinyl acetate in the copolymer being in the range 10% to 50% by weight, and a fragrancing substance.

Such an article can be useful for instance in fragrancing confined spaces which are subject to heating, such as airing cupboards or dishwashers, these spaces tending otherwise to become stale in some circumstances.

Preferably the percentage of vinyl acetate in the copolymer lies in the range 20% to 30%, and more preferably is 24%, or of the order of 24%, for instance 22% to 26%.

It has been found that embodiments of the present invention are particularly suitable for use as dishwasher fragrancers, it being possible to obtain a controlled release of fragrance over time in spite of the working temperatures to which such fragrancers might be subjected. In addition to obtaining the controlled release of the fragrance, it has also been found that embodiments of the present invention show suitable hardness and do not soften unduly at the temperatures to which they might be subjected in use as a dishwasher fragrancer, this otherwise being a potential problem with fragranced articles constructed from plastics materials. For instance, embodiments of the present invention remain viable at temperatures of 60°C and over, or at temperatures of the order of 90°C.

Further, embodiments of the present invention continue to operate^" satisfactorily in spite of the water and cleaning materials to which they might normally be subjected in a dishwasher,

A dishwasher fragrancing tag made according to an embodiment of the present invention may conveniently comprise a body of fragranced ethylene vinyl acetate copolymer, as described above, having attachment means for attaching it to a structure inside a dishwasher, such as a tail portion which can be held in a demountable loop about a structure such as a dish rack inside the dishwasher.

A dishwasher fragrancing tag according to an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which:

FIGURE 1 shows a perspective view of the tag; and

FIGURE 2 shows in graphical form the variation of SHORE A hardness of ethylene vinyl acetate copolymer with the weight percent vinyl acetate content.

Referring to Figurel, the dishwasher fragrancing tag 1 comprises a generally lemon shaped but planar body portion 2 with a stalk-like tail portion 3. The body portion 2 is provided with an aperture 4 in the region of the tail portion 3 while the tail portion 3 is provided with an enlarged end 5. The material of the tail portion 3 is sufficiently flexible that it can be doubled over, its end 5 being passed through the aperture 4 so as to be retained thereby, the tail portion 3 then forming a loop. The tag 1 can thus be demoun ably retained on a structure, for instance on a strut of a dishwasher rack, by constructing the loop around a part of the structure.

The tag 1 comprises an ethylene vinyl acetate copolymer, incorporating a fragrance and colouring. There are various constraints on a material for use in circumstances of this kind, these being for instance that the material should be sufficiently hard to survive a reasonable length of time while maintaining its shape, that - 4 -

its fragrancing characteristics should be predictable, and that these things should be maintained even under the working conditions encountered in a dishwasher. For instance, the tag may be subjected to temperatures of the order of 90°C, this potentially having a significant effect on the fragrance-holding characteristics of the material as well as on its physical parameters such as hardness.

According to the present invention, it has been found that certain copolymers of ethylene and vinyl acetate have the required desirable characteristics, taking into account the normal working conditions of a tag for use in a dishwasher. In particular, copolymers wherein the weight percent of vinyl acetate lies in the range from 10% to 40% or 50% have been found suitable, more particularly where the weight percent lies in the range 20% to 30%, and even more particularly where the weight percent is of the order of 24% vinyl acetate.

The material of the tag further comprises a fragrancing substance known as "QUESTIC". Questic is an inexpensive, versatile perfume additive for plastics which can be obtained in liquid form or in master batches, based on a polymeric material.

QUESTIC in a liquid form has been found to cooperate predictably with the ethylene vinyl acetate (EVA) copolymers described above to provide the controlled release of fragrance Over time, in a dishwasher. QUESTIC is a material supplied to order by D.R. Munden Quest International of Britain, however, other fragrancing materials may also be found suitable.

The particular EVA copolymer used in producing the tag 1 is known as C-I-L 2410 and is manufactured according to the general method of polymerizing ethylene and vinyl acetate together, to produce a structure as follows:

The inclusion of vinyl acetate to the molecule reduces the level of crystallinity in the polymer, hence affecting the properties of the material. The particular properties of C-I-L 2410 are as follows:

TYPICAL

PROPERTY VALUE UNIT

Vinyl acetate 24

Melt index 3 g/lOmin

Density 943 kg/m³

Tensile strength at break 22.4 MPa

Elongation 830 %

Referring to Figure 2, the proportion of vinyl acetate to ethylene in the copolymer is particularly important in achieving a tag suitable for use as a dishwasher fragrancing tag. As can be seen from Figure 2, the material becomes relatively hard, that is having a SHORE A hardness of 94 or 96, where there is substantially no vinyl acetate content. As the vinyl acetate content increases, the hardness drops, the graph showing a maximum vinyl acetate content of 40%, the SHORE A hardness at this level being 50. The most preferred content of vinyl acetate is of the order of 24%, the SHORE A hardness of the material being about 83 at this level. However, other proportions of vinyl acetate content are acceptable, including a content lying in the range from 10% to 40% or 50%, or more preferably in the range 20% to 30%, depending on the application for which an embodiment of the invention is to be used. The graph in particular shows the following range of approximate values of SHORE A hardness plotted against vinyl acetate content:

VINYL ACETATE CONTENT SHORE A HARDNESS ( t %)

0 94, 96 5 94 9 94 14 92 18 89 24 83 28 78 33 70 40 50

As can be seen, there is a certain spread of values of SHORE A hardness at each value of vinyl acetate content and, at 24% vinyl acetate content for instance, it is likely that a slight range of values, from perhaps 22% to 26% vinyl acetate content, will give a hardness of substantially 83.

The widest of the ranges mentioned represents a range of embodiments of the present invention which show acceptable characteristics of performance in a dishwasher environment. Within this range, the tag 1 does not unduly soften during use, and also accepts fragrancing to a sufficient degree during manufacture, subsequently releasing it over a reasonably and predictably sustained period. For instance a product within this range might be guaranteed to operate satisfactorily for at least five or ten washes. The second of the ranges mentioned shows improved characteristics, and might be guaranteed for at least ten or fifteen washes, while a weight percent of vinyl acetate of the order of 24%, for instance in the range 22% to 26%, has been found optimal. An embodiment having this last value of vinyl acetate content can be guaranteed for a minimum of twenty one washes.

Another factor which has been found significant in the performance of a dishwasher tag 1 in use is the thickness of the body portion 2 of the tag. In the embodiment shown in Figure 1, the tag has a sheet like form, having approximately the profile and dimensions of a lemon when seen in plan view. However, the sheet of material is only about 4 mm thick and it has been found that this is close to the minimum thickness at which a tag 1 of this type will perform satisfactorily, having a vinyl acetate content of 24%. If the thickness is significantly reduced, for instance to less than 2 mm, the tag loses its shape in the dishwasher environment. If the thickness is significantly increased, for instance to 8 mm or 10 mm, with 24% vinyl acetate content and the same content of fragrance, however, it will perform substantially similarly to the 4 mm embodiment, but will of course take up more space in a dishwasher and be of increased weight which may be a disadvantage.

It should be noted that the minimum thickness at which a tag 1 will show a satisfactory performance will be strongly affected by the hardness of the material of the tag. The optimum thickness of 4 mm for the tag described above, having 24% vinyl acetate content, is selected primarily on the basis that it is close to the minimum thickness at which the tag 1 will maintain its shape, and therefore wastes very little of the materials used to fabricate the tag 1. However, if an embodiment of the present invention is made which has a reduced vinyl acetate content, and which is therefore harder, it may still maintain its shape in use at lower thicknesses.

In a method of manufacturing a dishwasher fragrancing tag according to an embodiment of the present invention, beads of the ethylene vinyl acetate copolymer and the QUESTIC liquid fragrance are mixed in the ratio of three parts copolymer to one part liquid fragrance, the fragrance being completely absorbed by tumbling or mixing with the beads of copolymer and the mixing operation being terminated when the beads have absorbed all the fragrance and become dry. Colouring can then be mixed into the beads, or alternatively during a later moulding step. (Suitable colourants for such an application are known and are not therefore further described herein. ) The beads with incorporated fragrance are then fed into an injection moulding machine. The machine heats the beads to a temperature lying in the range from 130°C to 170°C until the beads melt to provide a liquid feed material to be injected into the dye for producing the required shape. After cooling for approximately 15 seconds the plastics material has hardened to a usable form. This moulded product is then sealed into non-porous containers and packaged.

Although the particular embodiment of the invention as described above is a dishwasher fragrancing tag, other applications may be relevant for a product having the characteristics particularly of hardness and reliability of fragrance release as described above. For instance, further embodiments of the invention might comprise a fragranced article for use in airing equipment such as heated airing cupboards which operate at temperatures of the order of 40° or 50° where previous fragranced products might exhibit characteristics such as too short an active life to be useful.

Many modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention. For instance, the amount of fragrance added may of course be varied.

Claims (7)

- CLAIMS -

1. A fragranced article for use in environments in which the temperature rises significantly above room temperature, the article comprising a body (2) of ethylene vinyl acetate copolymer incorporating a fragrancing substance, the weight percent proportion of vinyl acetate in the copolymer lying in the range from 10% to 50%.

2. An article according to claim 1, wherein said temperature rises to at least 50°C.

3. An article according to claim 1, wherein said temperature rises to the order of 90°C or above.

4. An article according to any one of the preceding claims, further comprising attachment means ( 3, 4, 5) for attaching the article to a structure.

5. An article according to claim 4, wherein said attachment means (3, 4, 5) comprises a demountable loop.

6. An article according to any one of the preceding claims wherein the weight percent proportion of vinyl acetate in the copolymer lies in the range from 20% to 30%.

7. An article according to any one of the preceding claims wherein the weight percent proportion of vinyl acetate in the copolymer is of the order of 24%. 1 8. A method of fragrancing a confined space which is

2 subject to heating in use, said method comprising placing an

3 article according to any one of the preceding claims in said

4 confined space. ' 5

6

7 9. A method according to claim 8 wherein said confined

8 space is comprised by a dishwasher. 9

10

11 10. A method according to claim 8 wherein said confined

12 space is comprised by airing equipment. 13

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