Japanese Patent No. 62-235,364 discloses a deodorant resin composition and articles molded from the resin containing thermoplastic resin and a deodorizing component. A deodorizing component comprised of a 10%-90% zinc compound such as citrate and 90%-10% of an aliphatic polycarboxylic acid such as citric acid is disclosed. In addition, the deodorizing resin composition masks, rather than chemically reacts with aldehydes or other producers of foul odors. This composition is not formulated to serve as a cleaning agent or to function in an aqueous dispersion. The disclosure is limited to use of a divalent zinc compound, which renders it toxic. Japanese Patent No. 64-8972 teaches an aqueous deodorant dispersion comprised of zinc compounds and aliphatic polycarboxylic acids, such as citric acids, or their salts. The disclosure is limited to zinc compounds. As a consequence, the deodorant compound would be toxic.

Japanese Patent No.63-161,968 discloses a deodorant composition containing an acidic substance and a ferrate material impregnated with a clay mineral containing polyvalent metal cations. The disclosure is limited to divalent compounds and does not teach a non-toxic compound product. This formulation does not include a cleansing agent or provide for an aqueous dispersion form.

U.S. Patent No.3,650,968 discloses a fisherman's soap composition for removing fishy odors. The composition consists of a source of citric acid, a detergent effective in an acid pH range, glycerin, and water. This reference does not teach use of a monovalent salt of citric acid.

U.S. Patent No. 4,089,942 discloses a cosmetic deodorant composition and process which prevents the formation of odors due to bacterial decomposition of perspiration by maintaining perspiration within a pH range of

3 to 6. The deodorant composition includes a cosmetic carrier, an organic acid such as citric acid, and a salt of an organic acid. Nothing in this reference teaches a composition or method for odor absorption.

U.S. Patent No. 4,690,772 describes sterilant compositions making use of a water soluble sterilant, a buffer, and a water soluble acid. Among the suggested acids is citric acid, whereas sodium citrate is disclosed as a possible buffering agent. In use, the compositions of this invention are formed as aqueous solutions having a pH of about 7.3, and are very dilute. It is believed that compositions of this character, because of the dilute nature thereof, would be very

- - ineffective as odor reducers; in any event, this utility is nowhere taught or suggested in the '772 Patent.

U.S. Patent No. 4,839,086 describes compositions useful for the regeneration of cation exchange resins typically found in water softening systems. The compositions described in this patent have been commercialized by JaCam

Chemical Co. of Sterling, Kansas, and include therein citric acid, a major proportion of a salt of citric acid (sodium citrate), as well as a small quantity of anti-caking agent. The prior art contains no suggestions, however, that composi¬ tions of the type described in Patent No. 4,839,086, could be useful in the context of odor reduction.

Summary of the Invention

The present invention overcomes the problems noted above, and provides a greatly improved class of odor-reducing materials. The latter can be formulated and used as dried, particulate compositions, or as relatively concentrat¬ ed aqueous dispersions. In other instances, the compositions of the invention may be incorporated into a cleansing agent. These types of combined compositions broadly include a cleansing agent (e.g. a soap or detergent) along with an odor- reducing composition mixed with the cleansing agent. The odor-reducing composition includes respective quantities of citric acid and a monovalent salt of citric acid as active ingredients.

The odor-reducing method of the invention involves contracting a substrate exhibiting odors to be reduced with a composition of the type described above, i.e., one including respective quantities of citric acid and a monovalent salt of citric acid. Correspondingly, such a composition may be placed adjacent to an area or zone exhibiting such offensive odors.

The compositions and methods of the invention are usable for absorbing or reducing odors on a wide variety of substrates such as landfills, municipal solid wastes, garbage, human skin, cloth or other absorbents (e.g. litterbox fills); or in open areas such as refrigerators.

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Description of the Preferred Embodiments

Odor-reducing compositions in accordance with the invention may be fabricated and used in a multitude of forms. For example, the compositions may be in particulate form, and in such instances would include from about 0.1 to 20% by weight citric acid, and at least about 50% by weight of a monovalent salt of citric acid. A salt of any of various monovalent species may be employed, including ammonium and alkali metals such as potassium, sodium, and lithium. In particularly preferred forms sodium or potassium is employed. The resultant product is non-toxic, food-grade, and safe for domestic as well as commercial use. As constituted, the particulate compositions have essentially no odor, but if desired, additives for giving the compositions a pleasant smell may be used. More particularly, such particulate compositions would include from about 0.1 - 30% by weight citric acid, and from about 70 to 99% by weight of citric acid monovalent salt. Moreover, in order to improve the handling properties of such particulate compositions, they would normally also include a minor amount of an anti-caking agent such as a mixture of mono and dimethyl naphthalene sulfonate sodium salts. A composition of this character is sold by Desoto, Inc. of Des Plaines, Illinois under the designation "Petro AG Special Superfine Powder."

Compositions made in accordance with U.S. Patent No. 4,839,086 are particularly useful as particulate odor-removing compositions in the invention.

Such compositions have heretofore been sold by JaCam Chemical Co. of Sterling, Kansas under the trademark Tronfite", for use in the regeneration of cation exchange resins. The Tronfite" product includes about 97.9% sodium citrate, about 2% by weight citric acid, and about 0.1% by weight of the above-described anti-caking agent, and is sold as a particulate powder. Alternately, a mixture of about 80% by weight sodium citrate and 20% by weight citric acid may be used, mixed with a minor amount of anti-caking agent.

If desired, the particulate compositions of the invention may be used directly, or alternately may be incorporated into a cleansing agent. For example, a hand cleanser commercialized under the designation "Gojo" may be used to good effect, with the addition of from about 2-20% by weight of the particulate odor-reducing composition described above mixed therein. More preferably, about 10% by weight of this particulate odor-reducing composition is employed. In such cases, the combined cleanser/odor-reducer may be simply rubbed on to the hands or skin of the user in the normal fashion, and then rinsed

- - off with water. Offensive odors on the skin are virtually completely absorbed or removed by the composition. In other cases a supply of the particulate material may be placed within or in proximity to an area or region exhibiting unpleasant odors. In other forms of the invention, the citric acid/citric acid monovalent salt materials may be dispersed in an aqueous medium such as water. Here again, use of such an aqueous dispersion would involve contacting the dispersion with a substrate to be treated, followed by rinsing; or placing a container of the liquid in an area to be deodorized. Preferably, the liquid forms of the present invention would include therein at least about 1.5% by weight citric acid, and at least about 15% by weight of a monovalent salt of citric acid; more preferably, the compositions would include in excess of about 2% by weight citric acid, and in excess of about 25% by weight of the salt. In actual practice, liquid compositions have been formulated having 2.2% by weight citric acid, 42.2% by weight sodium citrate with the balance being water. Such liquid compositions can be conveniently used by spraying or dripping them onto an area or substrate to be deodorized. Moreover, these compositions, as well as the corresponding particulate forms, can be readily handled and do not harm human skin.

Where the particulate compositions in accordance with the invention are used directly or incorporated into a cleansing agent, it is advanta¬ geous that the particle size of the particulate ingredients be relatively small, and preferably between about 50 and 100 standard mesh size. Also, it is preferred to apply the dried, particulate compositions onto substrates that are either inherently moist or premoistened prior to application of the particulate compositions; this enhances the desired deodorizing action.

U.S. Patent No. 4,839,086 is hereby incorporated by reference herein.