DESC:FIELD OF THE INVENTION
The present invention relates to an air freshener. More particularly, the present invention relates to a substrate impregnated with a fragrance that provides a controlled passive release of the fragrance for a prolonged period.
BACKGROUND OF THE INVENTION
The environment of an enclosed space such as a kitchen, a toilet or a bathroom may be rendered unpleasant by pungent odours. The common practice, therefore, is to mask or modify the unpleasant atmosphere by some sort of air freshener.
Various air freshener systems in the form of air freshener patches, sprays, candles, oils, gels, beads and plug-ins have long been sought by consumers in both residential and commercial environments. In an attempt to meet the demand for air fresheners or deodorizers, numerous products have been developed and are presently available in the marketplace. In general, most of these products are sold as solids, liquids, or aerosol sprays to provide the desired effect and to eliminate, chemically change, or mask the existing odor. Typically, products known in the art work by masking malodor, absorbing odorous molecules, dissolving or emulsifying such molecules, or killing bacteria that cause the offensive odour.
Various compositions and devices meant to release a fragrance over a long period of time are well known. The fragrances employed include both aromatic and perfumed compositions. An early form of such a device, and one still in use, was a pomander made by studding an apple or orange with cloves and useful as a garment sachet. Another approach still in use is to enclose dried leaves or flower petals in a perforated bag, box or other container. More recently, various solid substrates such as waxes or polymeric materials have been impregnated with fragrances for use, for example, as room fresheners. In such applications, a steady and controlled rate of release of the fragrance from the substrate is a desirable attribute. The uses of waxes or polymeric materials as substrates or carriers has the further advantage that the fragrance-containing materials can readily be formed or cut into virtually any desired shape or size. Notably, air fresheners in the form of the patches that can be removably attached to the intended article are also known in the art.
U.S. Patent No. 4,254,179 issued to Carson et.al describes a method and apparatus for impregnating a porous foam product with a fragrance that can be released over an extended period of time.
U.S Patent No. 4,880,690 discloses a perfume patch comprising a fragrance-emitting member having fragrance dispersed within an ultra-thin polyurethane membrane. A layer of pressure sensitive adhesive is applied to adhere the member to a surface. The polyurethane is formed from a diisocyanate, a macroglycol, and acrylyl chain terminators to which photoinitiator and fragrance oil are added prior to curing. A barrier layer may be applied by an adhesive or other suitable means to prevent migration of the fragrance oil to the adhesive so that no residue of adhesive remains on the surface. The perfume patch preferably includes a support for the fragrance-emitting member for ease in application and handling.
U.S Patent No. 4,720,409 discloses an improved air freshener in the form of a film laminate wherein the artwork is screened onto the front surface of a transparent plastic backing film which is laminated to a transparent, fragrance emitting face film, the rear surface of the backing film being adhered to a bathroom or kitchen tile whereby the artwork is effectively sandwiched between the backing and face film is thereby protectively shielded. The fragrance emanating from the air-freshener is thus thematically related to the artwork displayed so that the viewer’s visual impression is accompanied by an olfactory impression.
Despite the extensive research, researchers failed to provide an air freshener patch which can provide controlled passive release for extended periods. The commercially available air freshener patches do not meet the above requirements. Part of the problem lies in the relatively high loading of fragrance in the non-woven or porous substrate. On loading fragrance above threshold limit, either it oozes out from the substrate or negatively impacts the adhesive layer.
The oozing out of the fragrance can be avoided by modifying the rheology of the fragrance or by increasing the size of the non-woven substrate. But modifying the rheology does not allow the matrix of the non-woven to absorb the fragrance. Further, increasing the size of the non-woven substrate will hamper the portability of the product.
In order to address the above issues, there exists a need for an air freshener patch with a unique combination of a fragrance, a porous substrate and adhesive, that is not only long lasting but also free from the drawbacks such as oozing out of fragrance and loss of adhesive property of the adhering layer.
SUMMARY OF THE INVENTION
The present invention is broadly related to an air freshener patch 10, which releases a volatile fragrance over an extended period.
In accordance with an embodiment of the invention, there is provided an air freshener patch 10 comprising a fragrance emitting substrate 60 and a volatile fragrance 30 impregnated within the fragrance emitting substrate.
In accordance with yet another embodiment of the invention, the fragrance emitting substrate 60 is selected from the group consisting of ethylene-vinyl acetate (EVA), poly ethylene, cellulose paper, polyurethane, velvet fabric and spun bond non-woven substrate and is preferably polypropylene spun bond non-woven substrate having a Gram per square meter (GSM) value in the range of 100 to 500.
In accordance with still another embodiment of the invention, the volatile fragrance 30 is selected from the group consisting of perfumes, essential oils, bio-active fragrances that also destroy micro-organisms or repel insects, fragrances that mask odor or remove odor and combinations thereof and wherein the vapour pressure of the fragrance is between 1 to 2 kPa at 25 °C.

In accordance with another embodiment of the invention, there is provided a patch 10 for use in conjunction with a surface, further comprising:
(a) a backsheet 15 having an inner surface 35 and an outer surface 40, wherein the outer surface of the backsheet is adheared with the fragrance emitting substrate 60; and
(b) a double sided adhesive tape 19, comprising:
I. a carrier material 21 having a first surface 23 and a second surface 24;
II. a first adhesive layer 20 on the first surface 23;
III. a second adhesive layer 22 on the second surface 24; and
IV. a peel layer 25 removably adhered to the second adhesive layer 22.
wherein the first adhesive layer 20 is applied on the inner surface 35 of the backsheet 15.

In accordance with still yet another embodiment of the invention, the air freshener patch can be applied on a surface of any enclosed space such as a bathroom, a toilet, a shower cabin, a locker, a kitchen, a celler, a closet, a boat, an indoor swimming pool, a shoe, a room and so forth.
In accordance with a further embodiment of the invention, the air freshener patch 10 can be removably attached to the surface.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1. is an exploded view of an air freshener patch 10.
Figure 2. is a cutaway close-up of the air freshener patch 10.
The drawings are illustrative and not intended to be limiting, but are examples of embodiments, simplified for explanatory purposes, and not drawn to scale.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an air-freshener patch 10, comprising a fragrance-emitting substrate 60 impregnated with a volatile fragrance 30, which may optionally be used in conjunction with other supporting layers to form a composite article. The fragrance emitting substrate 60 impregnated with a volatile fragrance 30 can be used for many purposes in numerous places where evaporation will cause the volatile fragrance 30 to be released from the fragrance emitting substrate 60 to the environment. In the following description, the fragrance emitting substrate 60 impregnated with a volatile fragrance 30 will be described in reference to a preferred embodiment, that of an air-freshener patch 10. This embodiment is merely illustrative, and is not meant to be limiting.
The term “Surface” used herein refers to the outer boundary of an object. Figures 1 and 2 illustrate an example of an air-freshener patch 10 of the present invention. The air-freshener patch 10 includes a backsheet 15, a double sided adhesive tape 19, and a fragrance emitting substrate 60 impregnated with a volatile fragrance 30. The air-freshener patch may be applied on any surface or article within an enclosed space near which a pleasant odor is desired. The air-freshener patch 10 may be made flexible and soft for applying it uniformly on articles or surfaces with uneven shapes, dents and bumps.
The air-freshener patch of the present invention includes a backsheet 15. The backsheet 15 includes an inner surface 35, an outer surface 40, and a backsheet edge 45. The air-freshener patch 10 shown in Figure 1 is square in shape, however, the same may be of any suitable shape, such as geometric shapes, objects, numbers, letters, animals and so forth.
As illustrated in Figures 1 and 2 the air-freshener patch of the present invention also includes the double sided adhesive tape 19. The double sided adhesive tape 19 further comprises a first adhesive layer 20, a carrier web (also called a carrier material) 21, a second adhesive layer 22 and a peel layer 25. Non-limiting examples of materials that can be used to make the backsheet 15 and carrier material 21 include polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), poly ester (PE) and so forth. The first adhesive layer 20 of the double sided adhesive tape 19 is applied to the inner surface 35 of the backsheet 15.
Further, the carrier material 21 has a first surface 23 and a second surface 24. The first surface 23 carries the first adhesive layer 20 and the second surface 24 carries the second adhesive layer 22. Non-limiting examples of the adhesives that can be used for the adhesive layers 20 and 22 include Ethylene-vinyl acetate (EVA), polyolefin’s, starches, styrenic block copolymers (SBC), natural rubber, polybutylene, acrylics, polyurethanes, epoxies, polyesters, polyamides, silicones; a hot-melt adhesive including EVA, SBC, or amorphous poly-alpha-olefins (APAO); a synthetic adhesive such as an emulsion based formula (e.g., poly vinyl acetate (PVAc), EVA, and rubber including styrene-butadiene rubber and neoprene) or a solution-based formula (e.g. Kymene polyamideepichlorohydrin (PAE) resin available from Hercules, and poly-ethylene oxide); a water-based adhesive including either or both natural or synthetic ingredients including polymers, thickeners, fillers, tackifiers, humectants, and wetting enhancers; a natural adhesive including starches such as corn, tapioca, and wheat and such things as dextrin and animal glue; an adhesive binder including acrylic, ethylene ethyl, acrylate, PVAc, EVA, cellulose acetate, polyethylene, polypropylene, polyester, or poly vinyl chloride (PVC); and so forth, each of which can be used individually or in combination and is chemically resistant to the fragrance, i.e. its adhesive property is not affected by the fragrance. In other aspects of the present invention, the adhesive may be any other adhesive suitable for removably attaching the patch to the intended surface. The adhesive may be chosen to be a skin-friendly medically-approved body adhesive. Although shown in the Figures 1 and 2 to be of the same shape and size of the patch, the second adhesive layer 22 may be applied in an area smaller than the area enclosed by the edge of the backsheet 45. As illustrated in Figures 1 and 2 the double sided adhesive tape 19 includes a peel layer 25 removably attached to the second adhesive layer 22 to prevent the adhesive from sticking to other than the intended surface. The peel layer 25 is generally sized and shaped to match the size and shape of the backsheet 15. However, as shown in figures 1 and 2 the peel layer may extend beyond the edge 45 of the backsheet 15 or the edge 65 of the second adhesive layer 22, in the form of a tab 50, to facilitate removal of the peel layer 25 from the adhesive layer 22 prior to use of the patch on a suitable surface. Non-limiting examples of materials that can be used to make the peel layer 25 include paper, poly-coated paper, Super Calandered Kraft paper, Clay Coated Kraft paper, Machine Finished Kraft, Machine Glazed paper, polyester film, polyethylene terephthalate (PET), Bi-Oriented Polypropylene (BOPP), poly propylene (PP) plastic resins, high density poly ethylene (HDPE) film substrates, and so forth.
As illustrated in Figures 1 and 2 the fragrance emitting substrate 60 is merely a carrier substrate for the volatile fragrance 30. Non-limiting examples of substances that can be used as the fragrance emitting substrate 60 include ethylene-vinyl acetate (EVA), poly ethylene, cellulose paper, polyurethane, velvet fabric, spun bond non-woven substrate and so forth. Preferably, the fragrance emitting substrate 60 is polypropylene spun bond non-woven having GSM value in the range from 100-500 GSM and more preferably 240 GSM. Non woven fabrics are broadly defined as sheet or web structures bonded together by entangling fiber or filaments thermally. They are flat, porous sheets that are made directly from separate fibers. They are not made by weaving or knitting and do not require converting the fibers to yarns. Non-woven fabrics are new generation environmental friendly materials having attributes such as moisture resistance, flexibility, light weight, color vibrancy, affordability and recyclability. The fragrance emitting substrate 60 is the outermost layer (Figure 2) of said patch. Non-limiting examples of the volatile fragrance 30 present in the fragrance emitting substrate 60 include perfumes, essential oils, bio-active fragrances such as fragrances that also inhibit micro-organisms or repel insects, fragrances that mask odor or remove odor etc, wherein the fragrance has a vapour pressure of 1 to 2 kPa at 25 °C. An air-freshener patch 10 so formed may be sealed in an aluminium foil pouch or a pouch made from any other suitable material and disseminated to potential consumers.
EXAMPLES
Absorbancy test.
It was observed that fragrances containing Musk, Sandalwood, Tonka, Moss or Vanilla in their base notes and having vapour pressure values of 1 to 2 kPa at 25 °C, are optimum for use in this invention.
In order to shortlist the right fragrance emitting substrate 60, which can absorb the volatile fragrance 30, absorbancy test is crucial. The experiment described hereinbelow was performed to determine the loading capacity of the following fragrance emitting substrates: (a) polypropylene (PP) spun bond non-woven 120 GSM; (b) polypropylene spun bond non-woven 180 GSM; and (c) polypropylene spun bond non-woven 240 GSM. Each spun bond non-woven web that was bonded to the backsheet 15 by extrusion lamination was cut into five 8 × 8 cm2 test specimens and weighed. The fragrance emitting substrate 60 (bonded to the backsheet 15) was soaked in the volatile fragrance for one hour. Thereafter, the substrate was removed and allowed to drip excess perfume for one minute. Finally, the weight of the volatile fragrance impregnated into the fragrance emitting substrate 60 (bonded to backsheet 15) was calculated to determine its absorbent capacity. The above procedure was repeated five times for each spun bond non-woven substrate and the results are presented in table 1. The loading of the perfume in terms of percentage by weight was found to be in the range from 30-54%.
Table 1. Volatile fragrance loading on fragrance emitting substrate.
S. No. % of Fragrance Absorbed by 120 GSM Non woven % of Fragrance Absorbed by 180 GSM Non woven % of Fragrance Absorbed by 240 GSM Non woven
1 33 42 52
2 32 45 52
3 30 43 50
4 33 41 54
5 34 42 50

Process for preparing the air freshener patch.
PP Spun Bond Non-woven 240 GSM is laminated with a polypropylene backsheet 15 by the extrusion lamination process. After that, the first adhesive layer 20 of the double sided adhesive tape 19 is applied onto the inner surface 35 of the backsheet 15 to form a sheet comprising a laminated spun bond non-woven and a double sided tape. Finally, the sheet is cut into squares of length 8 cm, and loaded with a suitable perfume (percentage loading is 15 to 20%) to form the air freshener patch 10 of the present invention. Preferably, the double sided tape 19 used in the present invention is 3M™ Double Coated Tapes with 3M™ Adhesive 420.
Release of volatile fragrance from air-freshener patch.
The air-freshener patch made by the above process was weighed and the release of the volatile fragrance was evaluated under standard conditions (25±2 °C, relative humidity = 50±5%). The air-freshener patch was weighed every 24 h to determine the amount of volatile fragrance released into the environment.

Sensory Evaluation
The odor of the air freshener patch, made by the above process, was organoleptically evaluated by ten semi trained panelists on the 1st, 3rd, 5th, and 7th day. They scored the intensity of odor on a 0-5 point scale (Table 2). The scores given by the panelists for various odor levels in the organoleptic analysis are presented in Table 3.
Table 2: Scores for various odor levels
Score Odor level
0 No odor
1 Slight
2 Definite
3 Moderate
4 Strong
5 Very Strong

Table 3: Average Scores of 10 panelists for various odor levels over a period of 7 days
Day Score
1st 5
3rd 4
5th 3
7th 3

It is clear from the organoleptic analysis that the odor level of the air-freshener patch of the present invention remained moderate to strong till the 7th day.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

CLAIMS:
We claim:
1. An air freshener patch 10, comprising a fragrance emitting substrate 60 and a volatile fragrance 30 impregnated within the fragrance emitting substrate.
2. The air freshener patch 10 as claimed in claim 1, wherein the fragrance emitting substrate 60 is selected from the group consisting of ethylene-vinyl acetate (EVA), poly ethylene, cellulose paper, polyurethane, velvet fabric and spun bond non-woven substrate, preferably polypropylene spun bond non-woven substrate having GSM value in the range from 100 to 500 and more preferably spun bond non-woven substrate having a GSM value of 240.
3. The air freshener patch 10 as claimed in claims 1 and 2, wherein the volatile fragrance 30 is selected from the group consisting of perfumes, essential oils, fragrances that also inhibit micro-organisms or repel insects, fragrances that mask odor or remove odor and combinations thereof.
4. The air freshener patch 10 as claimed in claims 1 to 3, wherein the volatile fragrance 30 has a vapor pressure in the range from 1 to 2 kPa at 25 °C.
5. The air freshener patch 10 as claimed in claims 1 to 4, further comprising:
(a) a backsheet 15 having an inner surface 35 and an outer surface 40, wherein the outer surface 40 of the backsheet 15 is adheared with the fragrance emitting substrate 60; and
(b) a double sided adhesive tape 19, comprising:
I. a carrier material 21 having a first surface 23 and a second surface 24;
II. a first adhesive layer 20 on the first surface 23;
III. a second adhesive layer 22 on the second surface 24; and
IV. a peel layer 25 removably adhered to the second adhesive layer 22;
wherein the first adhesive layer 20 is applied on the inner surface 35 of the backsheet 15.
6. The air freshener patch 10 as claimed in claim 5, wherein the backsheet 15 and the carrier material 21 comprises materials selected from the group consisting of polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), poly ester (PE), and combinations thereof.
7. The air freshener patch 10 as claimed in claim 5, wherein the first adhesive layer 20 and the second adhesive layer 22 is selected from the group consisting of Ethylene-vinyl acetate (EVA); polyolefin’s; starches; styrenic block copolymers (SBC); natural rubber; polybutylene; acrylics; polyurethanes; epoxies; polyesters; polyamides; silicones; a hot-melt adhesive; a synthetic adhesive; a water-based adhesive including either or both natural or synthetic ingredients; a natural adhesive and combinations thereof.
8. The air freshener patch 10 as claimed in claim 5, wherein the peel layer 25 comprises of materials selected from the group consisting of paper, poly-coated paper, Super Calandered Kraft paper, Clay Coated Kraft paper, Machine Finished Kraft, Machine Glazed paper, polyester film, polyethylene terephthalate (PET), Bi-Oriented Polypropylene (BOPP), poly propylene (PP) plastic resins, and high density poly ethylene (HDPE) film substrates.
9. The air freshener patch 10 as claimed in claim 5, wherein the backsheet 15 has an edge 45, the peel layer 25 includes a tab 50 extending outward beyond the edge 45 of the backsheet 15.
10. The air freshener patch 10 as claimed in claim 5, applied on a surface, wherein the surface could be that of a bathroom, a toilet, a shower cabin, a locker, a kitchen, a celler, a closet, a boat, an indoor swimming pool, a shoe, a room or any other enclosed space.
11. The air freshener patch 10 as claimed in claim 5, wherein the patch can be removably attached to the surface.