FIELD OF THE INVENTION
This invention relates to an air freshener and deodorizer. This invention particularly relates to a water soluble cum sublimable solid air freshener and deodorizer formulated in solid pressed formulations.
BACKGROUND OF THE INVENTION
For years, air fresheners, made of paradichlorobenzene (PDCB) and Naphthalene, in the form of cubes and blocks were used for freshening enclosed spaces, such as office spaces, rooms, closets, cars, bathrooms, urinals, sinks, and toilets. Later, perfumes and functional ingredients such as surfactants, germicides and so forth, were added to these blocks which improved the ability of the blocks to provide both cleaning and odor-masking properties. Likewise, attempts were made to enhance the longevity of the air fresheners and odour intensity, by increasing the perfume loading into the carrier material. However, such an approach leads to leaching out of the fragrance from the air freshener block and non uniform release of fragrance. Consequently, air fresheners continue to suffer from drawbacks such as low perfume loading, short life, syneresis, and low intensity of fragrance.
Attempts have been made in the past to enhance the perfume loading of the fragrance into the carrier material. United States Publication No. US 2013/0126634 A1 discloses a solid pressed air freshener and odor neutralizer composition which can include greater than 10% fragrance. The air freshener comprises a fragrance; preferably the fragrance is impregnated within a water soluble substrate made from a foamed vegetable starch, a surfactant and a solidifier. The solid formulations breakdown easily in the presence of water and may be sprayed, within the area to be freshened.
European Patent No. EP 0118625 B1 discloses the use of hexamethylcyclotrisiloxane as a scent carrier material in air fresheners, lavatory bowl blocks or urinal tablets, optionally in combination with further volatile or non-volatile additives for reducing the sublimation rate of the hexamethylcyclotrisiloxane, thereby increasing the longevity of the air freshener formulation.
United States Patent No. US 6254823 B1, discloses a biodegradable air freshener that breaks down in the presence of water to minimize solid waste, including a water soluble substrate including foamed vegetable starch and a liquid fragrance carried in the substrate. The liquid fragrance may be from about 0.01 to about 10 times the weight of the substrate. Because the substrate is made from a water soluble starch, it dissolves in water leaving little or no solid waste. Thus, said air freshener provides a ready, spill-proof source of fragrance to mask unpleasant odours or simply provide a pleasant scent. The air freshener provides controlled, long-lasting release of the fragrance. When the air freshener is spent, it is conveniently and completely disposable in a sink or toilet, where any residual fragrance freshens the sink or toilet. Even if the air freshener is disposed of by conventional means, it quickly breaks down when exposed to water and, therefore, does not take up space in landfills.
Notwithstanding the progress and advances in the field of air fresheners due to fragrance encapsulation technology, there exists ample scope and necessity in the art to further improve the performance of air fresheners, particularly those that are used as cubes or blocks in damp enclosed spaces, humid environment, urinals and toilet bowls, wherein contact with water, or high humidity triggers the release of fragrance from the solid air freshener block.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide an air freshener and deodorizer in solid pressed formulations.
It is another object of the invention to provide a solid air freshener block with controlled fragrance release for use in damp enclosed spaces, humid environment, urinals and toilet bowls.
It is yet another object of the invention to provide a solid air freshener block with fragrant microcapsule uniformly distributed in a sublimable phase wherein the fragrant microcapsule comprises fragrance and an encapsulating water soluble polymer.
It is yet another object of the invention to provide a method for the preparation of the solid air freshener block.
It is yet another object of the invention to provide the solid air freshener that is stable and does not experience significant fragrance weeping under normal conditions of usage.
Other aspects, advantages, and salient features of the present invention will become apparent to those skilled in the art from the following detailed description read in conjunction with the drawings.
SUMMARY OF THE INVENTION
The present invention relates to an air freshener or deodorizer. The air freshener, deodorizer of the present invention are water soluble cum sublimable formulations and formulated in solid pressed formulations.
The present invention relates to a solid air freshener and/or odour neutralizer comprising a fragrant microcapsule and a sublimable phase wherein the fragrant microcapsule comprises fragrance and an encapsulating polymer. In the fragrant microcapsule the fragrance is encapsulated in a water soluble polymer or moisture sensitive matrix polymer.
In accordance with an embodiment of the invention the solid air freshener comprises fragrance in a range from 1 to 30% by weight and water soluble polymer in a range from 70 to 99% by weight of the fragrant microcapsule.
The water soluble polymer used for encapsulation is selected from the group comprising of polyvinyl pyrrolidone, water soluble cellulose, polyvinyl alcohol, ethylene maleic anhydride copolymer, methyl vinyl ether maleic anhydride copolymer, melamine formaldehyde copolymer, polyethylene oxides, polyamide, polyester, copolymers or homopolymers of acrylic acid, polyacrylic acid, polystyrene acrylic acid copolymer, water soluble starch derivatives, polyvinyl alcohol, polysaccharide, hydrocolloid, natural gum, protein, starch granules, and combinations thereof.
In accordance with another embodiment of the invention the solid air freshener preferably comprises the water soluble polymer melamine formaldehyde copolymer and water soluble starch. The fragrance is selected from non-limiting examples of fragrances including essential oils, such as, d- limonene, eugenol, orange, lemon, eucalyptol (cineol), clove oil and like (fragrance could be anything, from synthetic or natural source). Further, in practicing the invention, commercially available fragrances including materials, such as, for example, Autre Melange, or MixTex 1 from Givaudan-Roure, France and like can be used. The sublimable phase material is selected from the group comprising of Paradichlorobenzene (PDCB), Durene, Hexamethylcyclotrisiloxane (HMCTS), Naphthalene and combination thereof.
In accordance with yet another embodiment of the invention the solid air freshener further comprises of dyes, pigments, oil-soluble pigments, phosphorescent agents, fluorescent agents, insect repelling compounds, antifungal ingredients, antibacterial actives, antimicrobial actives, UV and light stabilizer ingredients or mixtures thereof.
In accordance with yet another embodiment of the invention the solid air freshener is in form of urinal cube, solid pellet, tablet, powder, granules and flakes.Preferably, the solid air freshener is in shape of cube with dimensions 55mm*55mm*13mm or in shape of tablet of diameter 52 mm.

BRIEF DESCRIPTION OF THE DRAWINGS
The following drawings are illustrative of preferred embodiment for enabling the present invention, are descriptive of some methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Fig 1A. Shows the front view of the fragrant microcapsule
Fig 1B. Shows the isometric view of the fragrant microcapsule.
Fig 2. Shows the mechanism of release of fragrance from the fragrant microcapsule.
Fig 3. Shows the process of preparation of fragrant microcapsule with water soluble starch or melamine formaldehyde copolymer.
Fig 4. Shows the process of preparation of fragrant microcapsule with water soluble starch.
Fig 5. Shows the evaporation profile of the solid air freshener block.
Fig 6. Shows the olfactory evaluation of the solid air freshener block.
Detailed description of the invention
The preferred embodiment of the present invention will be described hereinafter in reference to the accompanying drawings.
It is to be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or”, unless the content clearly dictates otherwise. It should also be noted that by the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
As used herein, “weight percent,” “wt. %,” “percent by weight,” “% by weight,” and variations thereof refer to the concentration of a substance as the weight of that substance divided by the total weight of the composition and multiplied by 100. It is understood that, as used here, “percent,” “%,” and the like are intended to be synonymous with “weight percent,” “wt. %,” etc.
The solid air freshener of the present invention comprises a fragrant microcapsule and a sublimable phase. The fragrant microcapsule is uniformly distributed throughout the matrix of the sublimable phase. The solid air freshener block is for use in damp enclosed spaces, humid environment, urinals and toilet bowls, wherein contact with water, or high humidity triggers the release of fragrance from the solid air freshener.
Fragrance may be present in only the fragrant microcapsule or both the fragrant microcapsule and the sublimable phase.
The fragrance in the fragrant microcapsule and the sublimable phase may comprise of the same fragrance or of different fragrance.
The fragrant microcapsule comprises a fragrance encapsulated in a water soluble polymer or a moisture sensitive matrix polymer. The terms “a water soluble polymer” or “a moisture sensitive matrix polymer” essentially mean the same thing and are used interchangeably in the specification.
Figure 1A shows a fragrant microcapsule in which the active core fragrance (1) is enclosed in a layer of water soluble polymer or moisture sensitive matrix polymer(2). Figure 1B shows an isometric view of the fragrant microcapsule.
The “water soluble polymer” or “a moisture sensitive matrix polymer” means a polymers that dissolve, disperse, or swell in water. Water soluble polymer of the fragrant microcapsule will react with moisture present in the air and will dissolve partially leaving void spaces in the outer layer of the microcapsule through which fragrance will escape and diffuses in the air. In rainy season when humidity is usually high and there is reduced perception of fragrance. The solid air freshener of the present invention address this problem as water soluble polymer of the fragrant microcapsule dissolves at high humidity to release a burst of fragrance.
The non-limiting examples of water soluble polymer for use in the present invention is selected from the group consisting of polyvinyl pyrrolidone, water soluble cellulose, polyvinyl alcohol, ethylene maleic anhydride copolymer, methyl vinyl ether maleic anhydride copolymer, melamine formaldehyde copolymer, polyethylene oxides, polyamide, polyester, copolymers or homopolymers of acrylic acid, polyacrylic acid, polystyrene acrylic acid copolymer, water soluble starch derivatives, polyvinyl alcohol, polysaccharide, hydrocolloid, natural gum, protein, starch granules, and combinations thereof.
The water soluble polymer comprises not more than 70% by wt. of the fragrant microcapsule.
Figure 2 shows that in a fragrant microcapsule the outer layer of the water soluble polymer dissolves on coming in contact with moisture or water present in air. As a result void spaces are formed in the outer layer of the fragrant microcapsule through which the fragrance escapes and deodorizes.
In accordance with an embodiment of the invention, the sublimable phase operates as the "primary source for release of fragrance," so that the fragrance is first released primarily from the sublimable phase. As the sublimable phase "shrinks" or decreases in volume over time due to evaporation or other mechanism, exposure of the dispersed fragrant microcapsules to the ambient environment increases. These microcapsules incorporates the fragrance. Increased exposure of the fragrant microcapsules represents an increase in the surface area from which the fragrance can be released, i.e., the "effective fragrance-releasing surface area" of the solid air freshener can increase over time. In this manner, the fragrance component microcapsule gradually takes over as the "secondary source for release of fragrance" for the fragrance, providing for its sustained release.
Typically, fragrances or perfume agents are compounds or compositions that either increase or enhance an existing smell or odour, or that impart a specific agreeable smell or odour to a substrate. These fragrances may be solids, liquids, vapours, or any combination thereof. Furthermore, they may completely or partially change state before being incorporated into a fragrant microcapsule, while incorporated in a fragrant microcapsule, or after being partially or completely released from a fragrant microcapsule. Non- limiting examples of fragrances include essential oils, such as, for example, d- limonene, eugenol, orange, lemon, eucalyptol (cineol), clove oil and the like. Also useful in practicing the invention are commercially available fragrances which include materials, such as, for example, Autre Melange, or MixTex 1 from Givaudan-Roure, France and the like.
The fragrance in the fragrant microcapsule may be present in any effective amount. Advantageously the fragrance in the fragrant microcapsule comprises not more than 30% by wt. of fragrant microcapsule.
The fragrant microcapsule is uniformly dispersed throughout the sublimable phase so as to provide for the sustained release of an effective amount of the fragrance.
The sublimable phase material in the present invention means a compound that changes directly from a solid to a gas without passing through the liquid state. Non-limiting examples of sublimable phase material that can be used in the present invention include, but not limited to, Paradichlorobenzene (PDCB), Durene, Hexamethylcyclotrisiloxane (HMCTS), Naphthalene, and so forth, each of which can be used individually or in combinations thereof.
The solid air freshener of the present invention may additionally comprise dyes, pigments, oil-soluble pigments, phosphorescent agents, fluorescent agents, insect repelling compounds, antifungal ingredients, antibacterial actives, antimicrobial actives, UV and light stabilizer ingredients or mixtures thereof or other suitable colorants to provide aesthetic appeal to the final air freshener product.
Dyes may include FD&C and/or D&C Yellows, Reds, Blues, Greens and Violets, or really any other dye or pigment.
The water soluble polymers of the present invention can be formed into microcapsules during process of encapsulation. The microcapsules retain the fragrance and are easier to handle during subsequent operations. These microcapsules have virtually no odour. The fragrance can be released when contacted by moisture in the air or water of the place. Using the microencapsulation process described herein in the examples, the polymers form hollow microcapsules wherein the fragrance is enclosed in the microcapsule. The polymer microcapsules do not alter the properties of the fragrance. Any fragrance can be incorporated within the microcapsule. The system is particularly advantageous for controlling the delivery of fragrance to a specific place and/ or at a specific time, provides sustained release of the fragrance, spill-proof and leaving little or no solid waste.
There are several known techniques for microencapsulation of oil in the prior arts. These techniques include emulsification, spray-drying, coaxial electrospray system, freeze-drying, coacervation, and in situ polymerization.
Encapsulation technology is a key step in the microencapsulation of fragrance oils. It is generally applied for the encapsulation of bioactives in aqueous solutions, which can either be used directly in the liquid state or can be dried (spray- or freeze-drying) to form powders after emulsification. Therefore, it is a part of the microencapsulation process. For example, in spray- and freeze drying microencapsulation, the fragrant core and water soluble wall materials could be prepared by emulsion techniques before the final drying.
The fragrant microcapsule of the solid air freshener of the present invention may be prepared by in situ polymerization. In situ polymerization is the most commonly used method for the preparation of microcapsules. In situ polymerization results in the formation of a wall via the addition of a reactant into either the interior or the exterior of the core fragrance material. In in-situ polymerization no reactants are included in the core fragrance material. All polymerization occurs in the continuous phase rather than on both sides of the interface between the core fragrance material and the continuous encapsulating phase. As the water soluble polymer grows, it deposits onto the surface of the core material, where cross-linking reactions may occur alongside polymer chain growth, eventually forming a solid capsule shell. A polymer-based microcapsule shell is considered good due to its high strength and stability.
Spray-drying is a low-cost microencapsulation technology. Spray-drying involves the atomization of emulsions into a drying chamber at a relatively high temperature, which leads to very fast water evaporation and, therefore, crust is formed at fast rate and quasi-instantaneous entrapment of fragrant oils. The microencapsulation by spray-drying involves 4 stages, (i) preparation of the dispersion, (ii) homogenization of the dispersion, (iii) atomization of the emulsion, and (iv)dehydration, of the atomized particles. Ordinarily, in the 1st stage the water soluble polymeric wall materials are dissolved in distilled water with stirring. The solutions are kept overnight at room or refrigerator temperature to ensure full saturation of the water soluble polymer molecules and to avoid any changes due to temperature. The fragrant core material is added to the solutions with or without the addition of an emulsifier, depending on the emulsifying properties of the water soluble polymeric wall materials, and all this before entering into the 2nd stage. The formed emulsion must be stable over a certain period of time, before the spray-drying step, viscosity should be low enough to prevent air inclusion in the particle, and oil droplets should be rather small. Emulsion viscosity and particle size distribution have significant effects on microencapsulation by spray-drying. In order to obtain high encapsulation efficiency, optimal spray drying conditions must be used. The feed temperature, air inlet temperature, and air outlet temperature are the main factors in spray-drying that must be optimized. A person skilled in art is well aware of the optimum conditions with respect to different water soluble polymer.
The invention will be further described by reference to the following detailed non-limiting examples.
Example 1
In situ polymerization for microencapsulation of fragrance with melamine– formaldehyde resin
The microcapsule formation process is conducted by the emulsion of fragrance oil in a melamine– formaldehyde resin solution and a sonication process to emulsify the fragrance oil in the aqueous phase, then the resin is added under stirring and then adjustment of the emulsion pH to acidic and finally microcapsule shell formation takes place. This process promotes the reaction of melamine with formaldehyde at the interface of fragrance oil droplets, producing a cross-linked film of melamine–formaldehyde polymer as a microcapsule shell. The fragrance oil containing melamine–formaldehyde resin microcapsules results in smooth surface morphologies, and is capable of preserving the encapsulated fragrance for a sufficient period of time.
In Figure 3 it is shown that the melamine–formaldehyde precondensate and copolymer are 1st pre-crosslinked in water (step 1); fragrance oil is added (step 2) to form an O/W emulsion by agitation (step 3); the temperature of the emulsion is then raised leading to polymerization of the pre-crosslinked monomer and the copolymer to form a wall on the dispersed fragrance oil surface (step 4).
Example 2
Spray drying for microencapsulation of fragrance with starch
The process of microencapsulation with water soluble starch through spray-drying method is illustrated in Figure 4. The water soluble starch and any suitable fragrance is emulsified at 3000 rpm for 10 min at 30°C. The stable emulsion is spray dried at air inlet temperature of 175 °C and air outlet temperature of 90 °C. This leads to stable microcapsule with fragrant core encapsulated in water soluble starch.
Example 3
Process for preparation of the solid air freshener block
In a mixing vessel sublimable phase material is added followed by addition of the fragrant microcapsules as obtained from Example 1 or Example 2. To this mixture fragrance oil, a colouring agent and any other additional ingredient like pigments, oil-soluble pigments, phosphorescent agents, fluorescent agents, insect repelling compounds, antifungal ingredients, antibacterial actives, antimicrobial actives, UV and light stabilizer ingredients or mixtures is added. All the ingredients are mixed thoroughly around 20 minutes at room temperature (i.e. 25ºC), at 200 to 500 rpm speed in the mixer to give finely grinded uniformly mixed powder. This uniformly mixed powder is placed in a tableting machine to give solid blocks.
While the solid compositions can take many forms like cube, tablet, powder, granules or flakes for use in accordance with this invention, it has been found that effective use is obtained with tablets and cube of the compositions. The tablets can be of various sizes. Particularly effective are tablets having a diameter of about 52 mm and a thickness of about inch. The cube form of the solid air freshener are of preferable dimension 55mm*55mm*13mm. The size and shapes provided here are only for reference and not limited to the above mentioned design and dimensions.
The representative formulation are in Table 1

Formula-tion Composition (%w/w) Remark
Fragrance (encapsula-ted) Fragrance
Oil Dye/ Pigment Para-dichloro-benzene Total
Formulation - 1 1.00 0.00 0.10 q.s. to 100 100.00 Coloured rigid block without any fragrance leaching.
Formulation- 2 2.00 0.00 0.00 q.s. to 100 100.00 White rigid block without any fragrance leaching.
Formulation - 3 0.00 0.60 0.00 q.s. to 100 100.0 White rigid block without any fragrance leaching.
Formulation - 4 2.00 0.60 1.00 q.s. to 100 100.0 Coloured rigid block without any fragrance leaching.
Formulation - 5 0.1 0.60 0.10 q.s. to 100 100.0 Coloured rigid block without any fragrance leaching.
Formulation - 6 5.00 0.50 0.00 q.s. to 100 100.0 White rigid block without any fragrance leaching.
Formulation - 7 10.00 -- 1.00 q.s. to 100 100.0 Coloured rigid block without any fragrance leaching.
Formulation - 8 20.00 -- 0.10 q.s. to 100 100.00 Coloured rigid block without any fragrance leaching.

All the above formulation 1 to 8 are stable under the conditions of manufacture and there is no leaching of the fragrance.
Example 4
Controlled release of the fragrance from the solid air freshener block
The formulation 2 and 3 are evaluated for their stability and efficacy of giving fragrance. The result in Figure 5 show that the solid air freshener block releases fragrance at a controlled rate throughout a period of 30 days. In Figure 5, Example 2 and Example 3 are used as representative only. All the exemplified formulation 1 to 8 show similar effect.
Example 5
Olfactory evaluation of the solid air freshener block
The formulation 2 from Example 3 is evaluated for the intensity of the fragrance by a panel of experts at room temperature 25 °C and relative humidity 90% at pre-determined intervals of 5 days from 0 to 30 days. The evaluation was performed on a scale of 1 to 5
Scale Rating
1 Poor
2 Average
3 Good
4 Very good
5 Excellent

It is clearly seen from Figure 6 that the solid air freshener block of the present invention have a sustained release of fragrance over a period of 30 days.
The solid air freshener and/or odor neutralizer of the present invention may be used in the form of a room freshener, car freshener, bathroom freshener, toilet bowl block, and urinal cube.
While the invention has been described in detail according to preferred compositions and to preferred processes for using the same, it will be obvious to those skilled in the art that changes and modifications can be made without departing from the spirit or scope of the invention, and it is intended in the appended claims to cover such changes and modifications.

We claim:
1. A solid air freshener and/or odour neutralizer comprising a fragrant microcapsule, a sublimable phase and additives wherein the fragrant microcapsule comprises a fragrance and a water soluble polymer.
2. The solid air freshener as claimed in claim 1, wherein the fragrant microcapsule is uniformly distributed throughout the matrix of the sublimable phase.
3. The solid air freshener as claimed in claim 1, wherein in the fragrant microcapsule, the fragrance is encapsulated in the water soluble polymer.
4. The solid air freshener as claimed in claim 3, wherein the fragrance is in a range from 1 to 30% by weight of the fragrant microcapsule and water soluble polymer is in a range from 70 to 99% by weight of the fragrant microcapsule.
5. The solid air freshener as claimed in claim 3, wherein the water soluble polymer is selected from the group comprising of polyvinyl pyrrolidone, water soluble cellulose, polyvinyl alcohol, ethylene maleic anhydride copolymer, methyl vinyl ether maleic anhydride copolymer, melamine formaldehyde copolymer, polyethylene oxides, polyamide, polyester, copolymers or homopolymers of acrylic acid, polyacrylic acid, polystyrene acrylic acid copolymer, water soluble starch derivatives, polyvinyl alcohol, polysaccharide, hydrocolloid, natural gum, protein, starch granules, and combinations thereof.
6. The solid air freshener as claimed in claim 5, wherein the water soluble polymer is melamine formaldehyde copolymer and water soluble starch.
7. The solid air freshener as claimed in claim 1, wherein the sublimable phase material is selected from the group comprising of Paradichlorobenzene (PDCB), Durene, Hexamethylcyclotrisiloxane (HMCTS), Naphthalene and combination thereof.
8. The solid air freshener as claimed in claim 1, wherein the additives comprises of dyes, pigments, oil-soluble pigments, phosphorescent agents, fluorescent agents, insect repelling compounds, antifungal ingredients, antibacterial actives, antimicrobial actives, UV and light stabilizer ingredients or mixtures thereof.
9. A method for the solid air freshener comprises the steps of:
– preparing a fragrant microcapsule;
– adding the fragrant microcapsule and the sublimable phase material in a mixing vessel;
– homogenizing the fragrant microcapsule and the sublimable phase material to a fine powder; and
– putting the fine powder in a tableting machine and compressing under pressure to give the compressed solid air freshener.
10. The method for solid air freshener as claimed in claim 9, wherein the step of homogenizing takes place for around 20 minutes at room temperature (i.e. 25ºC), at 200 to 500 rpm speed in the mixer to give finely grinded uniformly mixed powder.
11. The solid air freshener as claimed in claim 1 and 10, wherein the solid air freshener is in form of urinal cube, solid pellet, tablet, powder, granules and flakes.
12. The solid air freshener as claimed in claim 10, wherein the solid air freshener is in form of cube and tablet.