WO2007133934A1

WO2007133934A1 - Aqueous food safe nanoemulsion cleaning composition

Info

Publication number: WO2007133934A1
Application number: PCT/US2007/067933
Authority: WO
Inventors: Maria Ochomogo; Aram Garabedian
Original assignee: The Clorox Company
Priority date: 2006-05-09
Filing date: 2007-05-01
Publication date: 2007-11-22
Also published as: WO2007133934A8

Abstract

The present invention is directed to stable, aqueous cleaning composition, in the form of an emulsion, comprising a food safe nonionic surfactant and an essential oil. The cleaning composition has a substantially neutral pH which makes it safe for consumers to use and also safe for cleaning a wide variety of surfaces, including but not limited to, glass, granite, marble, wood, tile, counter tops, etc. The food safe surfactants in the cleaning composition are beneficial because they meet the regulatory standards for no rinse cleaners of food contact surfaces, while still being capable of effectively cleaning hard surfaces. The cleaning composition is preferably in the form of a stable nanoemulsion, which leaves a clear, non-visible residue on the surface being cleaned. The small particle size of the nanoemulsion, about 50 nm or less, allows the composition to have a low contact angle and good wettablity over the surface being treated.

Description

AQUEOUS FOOD SAFE NANOEMULSION CLEANING COMPOSITON

BY INVENTORS: Maria Ochomogo and Aram Garabedian

BACKGROUND OF THE INVENTION

Field of the Invention

[001] The present invention relates to an aqueous, substantially neutral, food safe cleaning composition, which is effective at cleaning tough stains without streaking and filming. The cleaning composition is suitable for cleaning a wide variety of surfaces because of its substantially neutral pH and natural ingredients, which provide safe cleaning with low irritancy and low residue levels. The cleaning composition also relates to cleaners, which can be used without rinsing, on food contact surfaces and a wide variety of other surfaces, including but not limited to, glass, granite, marble, wood, ceramic and metal.

Description of Related Art

[002] A number of products have been developed for the purpose of disinfecting and cleaning various surfaces. Many of these products use toxic, irritating, non-food safe or poisonous chemicals and leave behind harmful residues on cleaned surfaces. Some of these toxic cleaners are difficult and inconvenient to use and others requires significant drying times or must be wiped or rinsed off the cleaned surface. There is accordingly a growing need for more natural and food safe cleaners.

[003] Essential oils are natural products commonly used in cleaners for their fragrances and antimicrobial properties, and attempts have been made to formulate cleaning and disinfectant solutions based upon essential oils. However, because of their hydrophobic nature, essential oils are not readily miscible in water. As a result, essential oils are often difficult to prepare in a form that will allow them to be readily incorporated into an aqueous solution. [004] U.S. Pat. No. 5,403,587 to McCue et al. discloses an antimicrobial composition that utilizes both a solvent and a surfactant to facilitate the formation of a homogeneous aqueous mixture of an essential oil. Although this disinfectant composition is more natural than some, it requires relatively high concentrations of a solvent and synthetic surfactant, causes the appearance of streaking and filming on treated surfaces. Additionally, the high levels of solvent and surfactant would leave behind significant residue levels making the disinfectant composition unsuitable for food contact surfaces and other porous surfaces.

[005] U.S. Pat. No. 6,518, 337 to Baker et al. teaches a composition safe for food contact surfaces comprising a film forming polymer and a release aid. Although this is a food safe composition, it is also designed to form a film on a surface that makes soils easier to remove. Since the composition forms a film on the surface being treated, it may not be desirable for a wide variety surfaces and particularly shiny and reflective surfaces that would be dulled by the presence of a film.

[006] U.S. Pat. No. 6,455,086 to Trihn et al. discloses a food and food contact cleaning composition comprising basic buffer, water-soluble bleach, a water-soluble antimicrobial and a perfume. The food contact cleaning composition disclosed by Trihn has a pH of about 10.5 to 13. This cleaning composition is safe for food contact surfaces but its basic pH makes the cleaning composition limited to a narrow range of substrates and soils. For example, alkaline cleaners cannot be used effectively on all types of substrates, as they tend to be corrosive to many metals. Additionally, the food contact cleaning composition is not formulated to leave a low residue on surfaces so it will not be desirable for cleaning reflective or glossy surfaces.

[007] U.S. Pat. No. 6,345,634 to Murch et al. teaches a cleaning composition containing only G.R.A.S. (Generally Regarded as Safe) ingredients. The cleaning composition comprises a nonionic surfactant, oleic acid, and organic polycarboxlic acid and has a pH of about 2.5 to 5.5. Since the cleaning composition taught by Murch has a relatively low pH, it may corrode or discolor the surface of any substrate, which is not acid-resistant. Additionally, acidic cleaners are effective on a limited range of soils. Finally the cleaning composition does not contain any teachings that does not create streaking and filming on the surface being cleaned.

[008] Although there are food contact safe cleaning compositions that are either acidic and food safe or basic and food safe, there is a need for a cleaning composition that is neutral and safe for food contact surfaces and a wide variety of other surfaces. Additionally, there is a need for an effective neutral cleaner for food contact surfaces which has a low residue and low irritancy.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure Ia shows the initial George Foreman Knock-Out™ Multi-Purpose Cleaner droplet on a silicon wafer.

Figure Ib shows the George Foreman Knock-Out™ Multi-Purpose Cleaner droplet on a silicon wafer after 2 seconds.

Figure Ic shows the George Foreman Knock-Out™ Multi-Purpose Cleaner droplet on a silicon wafer after 4 seconds.

Figure Id shows the dried George Foreman Knock-Out™ Multi-Purpose Cleaner droplet on a silicon wafer.

Figure 2a shows the initial Sample 2 nanoemulsion cleaner droplet on a silicon wafer.

Figure 2b shows the Sample 2 nanoemulsion droplet on a silicon wafer after 2 seconds.

Figure 2c shows the Sample 2 nanoemulsion droplet on a silicon wafer after 4 seconds.

Figure 2d shows the dried Sample 2 nanoemulsion droplet on a silicon wafer.

SUMMARY OF THE INVENTION

[009] The present invention is directed to an aqueous food safe cleaning composition for disinfecting, sanitizing, degreasing or cleaning surfaces, comprising a food safe nonionic surfactant, an essential oil and water. The cleaning solution contains only food safe ingredients. The surfactants used in the cleaning composition are mild, non-toxic and have low irritancy profiles. Even though the surfactants in the composition are mild, the cleaning composition provides excellent cleaning on tough soils without significant residue levels or streaking and filming. The cleaning composition is natural and neutral and therefore suitable for a wide range of cleaning applications and surfaces.

[0010] The cleaning composition comprises: an essential oil, a food safe nonionic surfactant and water. The essential oil component of the present invention is present at levels from about 0.01% to about 5%, by weight of the cleaning composition, preferably from about 0.1% to 2%, and most preferably from about 0.2% to about 1%. The levels of nonionic surfactant useful in the present invention are determined by cleaning and filming/streaking performance and also by the levels deemed safe as food safe. The nonionic surfactants of the present invention are present at levels of from at least 1%, by weight of the composition, preferably from about 1% to about 10%, and more preferably from about 1% to about 5%. The nonionic surfactants selected preferably have a hydrophilic- lipophilic balance (HLB) greater than about 10, more preferably a HLB of about 13 or greater. Suitable nonionic surfactants of the present invention have a pour point of about 20° F and are viscous but pourable at a temperature range of 34-40° F. The cleaning composition comprises water at levels of from at least 70%, by weight of the composition, preferably at least 80% and more preferably at least 90%.

[0011] The cleaning composition is in the form of a stable and clear microemulsion. The present invention provides microemulsions formed by mixing of an oil phase, an aqueous phase and a food safe nonionic surfactant. The microemulsions of the present invention form spontaneously and creates a nano self- structured liquid (NSSL). The NSSL is thermodynamically stable over a wide range of temperatures and has droplets in the size range of 10 to 100 nm. The NSSL is also aesthetically clear and stable upon dilution and forms droplets in the range of about 10 to 100 nm.

[0012] The present invention provides for a novel and completely natural composition, which exhibits excellent cleaning properties on a wide variety of soils without streaking and filming or leaving harmful residues on surfaces to which the cleaning composition is applied. The subject composition has a substantially neutral pH, is non- toxic and does not affect the skin, eyes, lungs or coloration of products being cleaned.

[0013] The features and advantages of composition of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the invention are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified systems or process parameters that may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to limit the scope of the invention in any manner.

[0015] All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference.

[0016] References herein to "one embodiment", "one aspect" or "one version" of the invention include one or more such embodiment, aspect or version, unless the context clearly dictates otherwise.

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

[0018] In the application, effective amounts are generally those amounts listed as the ranges or levels of ingredients in the descriptions, which follow hereto. Unless otherwise stated, amounts listed in percentage ("%'s") are in weight percent (based on 100% active) of the active composition alone, not accounting for the substrate weight. Each of the noted cleaner composition components is discussed in detail below.

[0019] The term "cleaners" refers to any composition which serves to remove or reduce unwanted or harmful materials such as soil, dirt or microbial contamination from a surface, and/or which imparts a desirable or beneficial aesthetic, health or safety effect to the surface such as depositing thereon a fragrance, color or protective coating or film. Cleaners may be used on a wide variety of surfaces including soft surfaces, hard surfaces, food contact surfaces, porous surfaces, nonporous surfaces, and animate and inanimate objects.

[0020] The term "equilibrium contact angle" refers to a quantitative measurement of the wetting of a solid by a liquid. It is the angle formed by the liquid at the three-phase boundary where a liquid, gas (or a second immiscible liquid) and solid intersect. It is a direct measure of interactions taking place between the participating phases (gas/liquid/solid or liquid/liquid/solid). Two different approaches are commonly used to measure contact angles of non-porous solids, goniometry and tensiometry. Goniometry involves the observation of a single drop of test liquid on a solid substrate. In goniometry, the equilibrium contact angle is determined by drawing a tangent at the contact where the liquid and the solid intersect. Tensiometry involves measuring the forces of interaction as a solid is contacted with a test liquid. If the forces of interaction, geometry of the solid and surface tension of the liquid are known the contact angle may be calculated.

[0021] The term "food safe" refers to compositions, which are comprised entirely of materials that are considered food grade, and/or Generally Recognized As Safe (GRAS) and/or Everything Added to Food in the U.S. (EAFUS). In the United States, ingredients pre-approved for food use are listed in the United States Code of Federal Regulations ("C. F. R."), Title 21. The term "food safe" includes compositions are both safe and suitable for direct application to food work surfaces, including but not limited to, cutting boards, sinks, and kitchen counter tops, as well as direct food contact surfaces, including but not limited to, plates, platters and silverware. Food safe materials may also include ingredients that are well established as safe, or have adequate toxicological and safety pedigree, can be added to existing lists or approved via a self-affirmation process.

[0022] The term "substantially neutral" means that the aqueous cleaning composition of this invention has a pH of about 5 to about 9. In preferred embodiments of the invention, the pH range of the cleaning composition is about 6.0 to about 8.0, more preferably the pH range is about 6.5 to about 7.5.

Essential Oil

[0023] The essential oil component of the present invention is present at levels from about 0.01% to about 5%, by weight of the cleaning composition, preferably from about 0.1% to 2%, and most preferably from about 0.2% to about 1%. Since the cleaning composition of the present invention may be formulated as either a concentrated solution or a dilute cleaner the nonionic surfactant should be in at least a 2: 1 ratio to the essential oil. The ratio of nonionic surfactant to essential oil is preferably from about 4: 1 to about 10:1.

[0024] The essential oils preferred for use in the aqueous compositions of this invention are those essential oils, which exhibit antimicrobial activity and which can form a microemulsion when combined with a water carrier and a nonionic surfactant. Suitable essential oils include, but are not limited to, those obtained from mint, tea tree, parsley, thyme, lemongrass, lemons, limes, grapefruit, oranges, anise, clove, roses, lavender, citronella, eucalyptus, peppermint, camphor, sandalwood, cedar and pine. Preferred essential oils include mint oil, tea tree oil, lavender oil, pine oil, lemongrass oil, lemon oil, parsley oil, orange oil and clove oil. The most preferred essential oils are mint oil, tea tree oil, lemon oil, orange oil, lime oil, grapefruit oil, mint oil, parsley oil, lemongrass oil and combinations thereof.

[0025] Other suitable essential oils include, but are not limited to: Anethole 20/21 natural, Aniseed oil china star, Aniseed oil globe brand, Balsam (Peru), Basil oil (India), Black pepper oil, Black pepper oleoresin 40/20, Bois de Rose (Brazil) FOB, Borneol Flakes (China), Camphor oil, White, Camphor powder synthetic technical, Cananga oil (Java), Cardamom oil, Cassia oil (China), Cedarwood oil (China) BP, Cinnamon bark oil, Cinnamon leaf oil, Citronella oil, Clove bud oil, Clove leaf, Coriander (Russia), Coumarin 69° C. (China), Cyclamen Aldehyde, Diphenyl oxide, Ethyl vanilin, Eucalyptol, Eucalyptus oil, Eucalyptus citriodora, Fennel oil, Geranium oil, Ginger oil, Ginger oleoresin (India), White grapefruit oil, Guaiacwood oil, Gurjun balsam, Heliotropin, Isobornyl acetate, Isolongifolene, Juniper berry oil, L-methyl acetate, Lavender oil, Lemon oil, Lemongrass oil, Lime oil distilled, Litsea Cubeba oil, Longifolene, Menthol crystals, Methyl cedryl ketone, Methyl chavicol, Methyl salicylate, Musk ambrette, Musk ketone, Musk xylol, Nutmeg oil, Orange oil, Patchouli oil, Peppermint oil, Phenyl ethyl alcohol, Pimento berry oil, Pimento leaf oil, Rosalin, Sandalwood oil, Sandenol, Sage oil, Clary sage, Sassafras oil, Spearmint oil, Spike lavender, Tagetes, Tea tree oil, Vanilin, Vetyver oil (Java), Wintergreen, Allocimene, Arbanex®, Arbanol®, Bergamot oils, Camphene, Alpha-Campholenic aldehyde, I- Carvone, Cineoles, Citral, Citronellol Terpenes, Alpha-Citronellol, Citronellyl Acetate, Citronellyl Nitrile, Para-Cymene, Dihydroanethole, Dihydrocarveol, d-Dihydrocarvone, Dihydrolinalool, Dihydromyrcene, Dihydromyrcenol, Dihydromyrcenyl Acetate, Dihydroterpineol, Dimethyloctanal, Dimethyloctanol, Dimethyloctanyl Acetate, Estragole, Ethyl-2 Methylbutyrate, Fenchol, Fernlol®, Florilys®, Geraniol, Geranyl Acetate, Geranyl Nitrile, Glidmint® Mint oils, Glidox®, Grapefruit oils, trans-2-Hexenal, trans-2-Hexenol, cis-3-Hexenyl Iso valerate, cis-3- Hexanyl-2-methylbutyrate, Hexyl Isovalerate, Hexyl-2-methylbutyrate, Hydroxycitronellal, lonone, Isobornyl Methylether, Linalool, Linalool Oxide, Linalyl Acetate, Menthane Hydroperoxide, I-Methyl Acetate, Methyl Hexyl Ether, Methyl-2 -methylbutyrate, 2-Methylbutyl Isovalerate, Myrcene, Nerol, Neryl Acetate, 3-Octanol, 3-Octyl Acetate, Phenyl Ethyl-2- methylbutyrate, Petitgrain oil, cis-Pinane, Pinane Hydroperoxide, Pinanol, Pine Ester, Pine Needle oils, Pine oil, alpha-Pinene, beta-Pinene, alpha- Pinene Oxide, Plinol, Plinyl Acetate, Pseudo lonone, Rhodinol, Rhodinyl Acetate, Spice oils, alpha-Terpinene, gamma-Terpinene, Terpinene-4-OL, Terpineol, Terpinolene, Terpinyl Acetate, Tetrahydrolinalool, Tetrahydrolinalyl Acetate, Tetrahydromyrcenol, Tetralol®, Tomato oils, Vitalizair, Zestoral®.

Nonionic Surfactant

[0026] The levels of nonionic surfactant useful in the present invention are determined by cleaning and filming/streaking performance and also by the levels deemed acceptable as food safe. The nonionic surfactants of the present invention are present at levels of from at least 0.5%, by weight of the composition, preferably from about 0.75% to about 10%, more preferably from about 0.75% to about 5% and most preferably from about 0.75% to about 2%. The one or more nonionic surfactants selected preferably have a hydrophilic- lipophilic balance (HLB) greater than about 10, more preferably a HLB of about 13 or greater. The HLB value of a nonionic surfactant blend is the weighted average of the blended surfactants. A HLB value of 10 or greater corresponds to forming a translucent to clear solution, which is beneficial for a multi-purpose cleaning composition. A high HLB value is also desirable for an aqueous composition because the higher the HLB the more hydrophilic the surfactant. Therefore oil-in- water emulsions, like that of the present invention, usually require nonionic surfactant with a medium to high value.

[0027] In one embodiment of the invention, suitable nonionic surfactants of the present invention have a pour point of about 20° F and are viscous, but pourable at a temperature range of 34-40° F. In one embodiment of the invention, the nonionic surfactants are food safe surfactants, including but not limited to, glycosides, sorbitan esters, ethoxylated sorbitan esters, sorbitan tristreate, monoglycerides, sucrose esters, ethoxylated castor oils, polyglycerol esters, and combinations thereof. Other suitable food safe nonionic surfactants include polysorbates, such as Tween 80, Tween 60 and Tween 20. In another embodiment of the invention the nonionic surfactant is a glycoside surfactant. In a preferred embodiment the glycoside surfactant is an alkyl polyglycoside. The alkyl polyglycoside surfactant may have linear or branched alkyl groups. Suitable alkyl polyglycoside surfactants preferably include a linear alkyl group. In preferred embodiment of the invention, the alkyl polyglycoside has about 6-22 carbons, more preferably about 6-12 carbons, even more preferably 6-10 carbons and most preferably 8- 10 carbons.

[0028] The microemulsions created with essential oil, Tween, propylene glycol and water create an exothermic reaction upon dissolution. A set of experiments was conducted to determine which ingredients are responsible for the exothermic reaction. First, a solution of propylene glycol was diluted with water yielding about a 5 to 7° F temperature change. Secondly, separate solutions of Tween 80 and Tween 20 were diluted with water resulting in about a 10 to 15° F temperature change. Finally, a concentrated nanoemulsion cleaning composition of 57% Tween 20, 11% essential oil, 16% propylene glycol and 16% water was diluted with water which created about a 15 to 20⁰F temperature increase. These results indicate that both the propylene glycol and the Tween surfactants are responsible for the exothermic reaction that results when the concentrated cleaning composition of the present invention is diluted with water.

[0029] The enthalpy change of solution is the quantity of heat produced or absorbed when a one mole of a substance is dissolved in a large volume of a solvent at constant pressure. In strong diapole interactions, the solute-solvent interaction may exceed the solvent-solvent interaction, resulting in excess energy in the form of heat. The dissolution process is termed an exothermic reaction with a negative heat of solution. The heat of solution of a substance is defined similarly: by energy absorbed, or endothermic energy, and energy released, or exothermic energy (expressed in "negative" kJ/mol). The heat of solution is one of the three dimensions of solubility analysis because a large negative heat of solution associated with exothermic reactions correlates to increased solubility.

[0030] In the present invention, the generation of heat as the cleaning composition is diluted with water is beneficial for a number of reasons. First, the generation of heat causes more of essential oil to be dispersed into the air, which enhances the fragrance of the cleaner to the consumer. Therefore, less essential oil may be used in the cleaning composition while maintaining the same fragrance benefit to a consumer using the cleaning composition. Secondly, the increase in heat upon dilution of the concentrated cleaner may aid in the removal of tough stains and soil on the surface being cleaned. Thirdly, the release of heat is also a beneficial consumer cue that the cleaning composition is actively working to remove soils on a surface. Finally, the cleaning composition is comprised of completely natural materials and has low irritancy levels so it may come in direct contact with a consumer's skin. The sensation of heat on a consumers skin creates a pleasant sensation and could provide the added benefit of aiding the skin's absorption of essential oils, fragrance, moisturizers, sanitizers, and other skin care products.

Cosurfactants

[0031] Although the disclosed food safe nonionic surfactants of the invention provide excellent cleaning performance, as shown in the examples which follow, it may sometimes be desired to add other surfactants to the formulations to obtain additional cleaning benefits. Such cosurfactants include anionic, cationic, zwitterionic, and/or amphoteric surfactants. The cleaning composition may include cosurfactants, but it may also be essentially free of any of the following cosurfactants: anionic, cationic, zwitterionic, amphoteric surfactants, and any combinations thereof. In one embodiment, the cleaning composition is essentially free of anionic surfactants. In another embodiment, the cleaning composition is essentially free of cationic surfactants. In another embodiment, the cleaning composition is essentially free of zwitterionic surfactants. In another embodiment, the cleaning composition is essentially free of amphoteric surfactants. Many of these cosurfactants are described in McCutcheon's Emulsifϊers and Detergents (1997), Kirk-Othmer, Encyclopedia of Chemical Technology 3rd Ed., Volume 22, pp. 332-432 (Marcel-Dekker, 1983), and McCutcheon's Soaps and Detergents (N. Amer. 1984), the contents of which are hereby incorporated by reference.

[0032] Illustrative nonionic surfactants are the alkyl polyglycosides, ethylene oxide and mixed ethylene oxide/propylene oxide adducts of alkylphenols, the ethylene oxide and mixed ethylene oxide/propylene oxide adducts of long chain alcohols or of fatty acids, mixed ethylene oxide/propylene oxide block copolymers, esters of fatty acids and hydrophilic alcohols. [0033] Illustrative anionic surfactants are the soaps, alkylbenzene sulfonates, olefin sulfonates, parafin sulfonates, alcohol and alcoholether sulfates, phosphate esters, and the like. Suitable alkyl diphenyl oxide disulfonates preferably include an alkyl chain group of C6-20. Alkyl diphenyl oxide disulfonates are available from Dow under the brand name Dowfax® or from Pilot Chemical under the brand name Calfax®.

[0034] Illustrative cationic surfactants include amines, amine oxides, alkylamine ethoxylates, ethylenediamine alkoxylates such as the Tetronic series from BASF, quaternary ammonium salts, and the like.

[0035] Illustrative amphoteric surfactants are those which have both acidic and basic groups in their structure, such as amino and carboxyl radicals or amino and sulfonic radicals, or amine oxides and the like. Suitable amphoteric surfactants include betaines, sulfobetaines, imidazolines, and the like.

[0036] The amounts of cosurfactants will generally be about the level of the nonionic food safe surfactant, or less. The cleaning composition of the present invention may optionally include additional surfactants

Solvent

[0037] The majority of the cleaning composition of the present invention comprises water. In addition, the essential oil, nonionic surfactant and water combination of the present invention spontaneously forms a microemulsion. These qualities allow the cleaning composition of the present invention to be formulated either as a concentrate that would be diluted prior to use or as a dilute cleaning solution, which is ready to use. As a dilute cleaning solution, which is readily applied to a surface, the water is at least 70%, by weight of the composition, preferably at least 80% and more preferably at least 90%.

[0038] In another embodiment of the invention, the cleaning composition may include other solvents in addition to water. Suitable other solvents include, but are not limited to, C2-16-alcohols, most preferred are ethanol, propanol, butanol, pentanol, glycerol or mixtures and/or isomers thereof. In one embodiment of the invention the cleaning composition is essentially free of monohydric alcohols, including but not limited to ethanol, methanol, isopropanol, n-propanol, and t-butanol. Other non- limiting examples of suitable solvents include: glycerin, 1, 3 -propanediol, ethylene glycol and propylene glycol or mixtures thereof. When present, the other solvents comprises about 0.1-10% by weight of the cleaning composition, preferably about 0.5 to 5%, and most preferably about 0.5 to 2%.

Buffers

[0039] Optionally, buffering and pH adjusting agents, can be added to the cleaning composition. Suitable buffers include, but are not limited to, organic acids, mineral acids, alkali metal and alkaline earth salts of silicate, metasilicate, polysilicate, borate, carbonate, carbamate, phosphate, polyphosphate, pyrophosphates, triphosphates, tetraphosphates, ammonia, hydroxide, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, triethanolamine, and 2-amino-2methylpropanol. Additional buffering agents for compositions of this invention include nitrogen- containing materials. Some examples are amino acids such as lysine or lower alcohol amines like mono-, di-, and tri-ethanolamine. Other nitrogen- containing buffering agents are tri(hydroxymethyl) amino methane (TRIS), 2- amino-2-ethyl-l,3-propanediol, 2- amino-2 -methyl- propanol, 2- amino-2-methyl-l, 3-propanol, disodium glutamate, N- methyl diethanolarnide, 2-dimethylamino- 2- methylpropanol (DMAMP), 1,3- bis(methylamine)-cyclohexane, 1 ,3-diamino-propanol N,N'-tetra-methyl-l ,3-diamino-2- propanol, N,N-bis(2-hydroxyethyl)glycine (bicine) and N-tris(hydroxymethyl)methyl glycine (tricine). Other suitable buffers include potassium citrate, ammonium carbamate, citric acid, acetic acid. Mixtures of any of the above are also acceptable. In one embodiment of the invention the cleaning composition contains only citric acid or citrate buffers and is essentially free from any other types of buffers. Useful inorganic buffers/alkalinity sources include ammonia, the alkali metal carbonates and alkali metal phosphates, e.g., sodium carbonate, sodium polyphosphate. For additional buffers see McCutcheon's Emulsifiers and Detergents, North American Edition, 1997, McCutcheon Division, MC Publishing Company Kirk and WO 95/07971, both of which are incorporated herein by reference.

[0040] When employed, the builder or buffer comprises at least about 0.001% and typically about 0.01-10% of the cleaning composition. Preferably, the pH adjusting agent or buffer content is about 0.01-5% and more preferably from about 0.05%- 2%.

Additional Adjuvants

[0041] In a further aspect of the present invention, the improved cleaning composition optionally includes one or more adjuncts. The adjuncts include, but are not limited to, fragrances or perfumes, waxes, dyes and/or colorants, solubilizing materials, stabilizers, thickeners, defoamers, hydrotropes, lotions and/or mineral oils, enzymes, bleaching agents, sanitizing or disinfecting agents, cloud point modifiers, preservatives, polymers and any combinations thereof.

[0042] The waxes, when used, include, but are not limited to, carnauba, beeswax, spermacet, candelilla, paraffin, lanolin, shellac, esparto, ouricuri, polyethylene wax, chlorinated naphthaline wax, petrolatu, microcrystalline wax, ceresine wax, ozokerite wax, and/or rezowax. The solubilizing materials, when used, include, but are not limited to, hydrotropes (e.g. water soluble salts of low molecular weight organic acids such as the sodium and/or potassium salts of xylene sulfonic acid). The acids, when used, include, but are not limited to, organic hydroxy acids, citric acids, keto acid, and the like. Thickeners, when used, include, but are not limited to, polyacrylic acid, xanthan gum, calcium carbonate, aluminum oxide, clays, alginates, guar gum, methyl, ethyl, clays, and/or propylhydroxycelluloses. Formulas may include various types of organic or inorganic abrasives to enhance cleaning and polishing properties such as, but not limited to, CaCO₃, SiO₂, walnut shell powder, etc. Defoamers, when used, include, but are not limited to, silicones, aminosilicones, silicone blends, and/or silicone/hydrocarbon blends. Lotions, when used, include, but are not limited to, achlorophene and/or lanolin. Enzymes, when used, include, but are not limited to, lipases and proteases, and/or hydrotropes such as xylene sulfonates and/or toluene sulfonates. Bleaching agents, when used, include, but are not limited to, peracids, hypohalite sources, hydrogen peroxide, and/or sources of hydrogen peroxide. Preservatives, when used, include, but are not limited to, mildewstat or bacteriostat, methyl, ethyl and propyl parabens, short chain organic acids (e.g. acetic, lactic and/or glycolic acids), bisguanidine compounds (e.g. Dantogard and Dantogard Plus both from Lonza, Inc. and/or Glydant) and/or short chain alcohols (e.g. ethanol and/or IPA).

[0043] The cleaning composition of the present invention takes the form of a microemulsion. In a preferred embodiment, the microemulsion of the present invention forms spontaneously and creates a nano self-structured liquid (NSSL). The NSSL is thermodynamically stable over a wide range of temperatures and has droplets in the size range of 10 to 100 nm. The NSSL is also asthetically clear and stable upon dilution and forms droplets in the range of about 10 to 100 nm. Furthermore, the NSSL may also form concentrates, which may be diluted as desired in either oil or water while a single phase is maintained and the nano- sized structured concentrate is intact. The NSSL concentrates form a clear and transparent liquid that shows no precipitates, crystalline matter or turbidity. The structured concentrate is of low viscosity, thermodynamically stable, does not separate, coalesce, aggregate, flocculate or cream at any ambient temperature even after prolonged storage.

[0044] The compositions can be packaged in any suitable materials and housings known to one skilled in the art. It may be packaged as a concentrate in suitable containers or in ready-to-use dispensing systems. Thus they can be packaged in aerosol form in conventional aerosol containers or in liquid form in trigger pump spray bottles and squeeze bottles or pump spray bottles to produce an aerosol using a pump mechanism to build the necessary pressure to produce the aerosol. The compositions can also be impregnated into substrates, including but not limited to, wipes, pads, sponges, foams, and cloths. The composition may also be used in conjunction with various household cleaning tools, including but not limited to, mops, vacuums, robotic cleaning devices like the Scooba® and Roomba®, toilet brushes, window cleaning tools, etc. The impregnated substrates are then used to deliver the cleaning composition to the hard or soft surface to be treated. These impregnated substrates can be packaged individually or in bulk form for individual dispensing.

[0045] The composition of the invention may be formulated to be dispersed from a ready-to-use dispenser system. Due to its natural, non-toxic, food safe composition, the solution does not need to be wiped off the surface. The resulting longer contact with the surface area being cleaned which can enhance cleaning performance. The subject composition is also non-corrosive and biodegradable. Since the cleaning composition is food safe and neutral it is suitable for a wide range of surfaces, including but not limited to, countertops, cutting boards, tile, ceramic, wood, tables, glass, ceramic, marble, granite, metal, food contact surfaces, and many other surfaces found in and around the home. The cleaning composition also has low irritancy so it is useful in situations where it may come into contact with a consumers skin. Additionally, the cleaning composition of the present invention has low streaking and filming and residue levels, as shown in the experimental data, which makes it an ideal all-purpose cleaner.

[0046] This aqueous cleaner can be used effectively in large-scale industrial cleaning processes, in smaller-scale laboratory or cleaning processes, or for home use in general purpose cleaning processes. Therefore, an advantage of the present invention is its wide- ranging applicability, as it can be used to clean a broad array of substrates which are contaminated with a broad array of soils.

FORMULATIONS

[0047] Suitable aqueous cleaning compositions of the present invention using glycoside surfactants include, but are not limited to the following formulations:

[0048] Suitable aqueous cleaning compositions of the present invention using polysorbate surfactants include, but are not limited to the following formulations:

EXPERIMENTAL

[0049] The compositions of the invention are illustrated by the specific formulations described below without being limited to those formulations. The following section contains non- limiting examples that are illustrative of the present invention: Residue is defined as either soil and/or cleaning product remaining after cleaning (sometimes referred to as filming and streaking). The terms "low", "medium" and "high" refer to increasing levels of undesirable residue. Table 1 : Residue Performance

[0050] The bacon grease residue performance tests were performed according to the following steps. First, 0.5 g of bacon grease was sprayed onto the center of each clean, black, porcelain enamel 8.5 by 11 inch tiles. The tiles with the bacon grease soil were then stored at 70⁰F temperature prior to testing. Each tile with the bacon grease soil was then weighed on a top loading balance capable of measuring to 0.1 grams. The balance is then tared with the tile in place. About 2.5 grams +/- 0.2 grams of product was pipetted onto a clean sponge. The tile was then wiped by running the sponge across the length of the tile surface using two sets of six pass wiping cycles in an evenly distributed fashion that covers the entire surface of the porcelain enamel tile. Wiping is completed using only the weight of the sponge. Finally, the sponge is flipped over and a similar six pass wiping cycle completes the process. Three replicates of each cleaning solution sample were tested.

[0051] For the cleaning product residue performance clean black, porcelain enamel tiles were used, to measure the amount of residue left by the cleaning solution. The test method for the tiles is the same as that outlined above for the bacon grease testing except that no soils are applied to the tiles prior to applying the test cleaning solutions. The cleaning solution is allowed to sit on the surface of the tile for about 30 seconds before wiping the surface dry with a sponge. Three replicates of each cleaning solution sample for overall residue were tested.

[0052] Residue performance data was generated using Image Analysis Instrumentation. Since each sample is tested in triplicate, the data from the three tests are averaged. For cleaning product residue, statistical data from image analysis studies had previously been correlated with consumer acceptability data for product residue. The consumer acceptability data is scaled to a range of 0-100, where low values indicate low residue (most consumer acceptable). In the table above, 1-40 is considered low residue, 40 to 60 is medium residue and 60 and above is high residue. The data gathered using the Image Analysis Instrumentation was scaled and then added directly into the above chart to show the residue performance of the cleaning composition of the present invention against other all-natural cleaners on the market and also against a non-natural all-purpose cleaner with a good residue performance profile, Formula 409® Cleaner/Degreaser.

[0053] For the bacon grease residue data, the numbers are the mean gray values taken directly from the imaging system. Since an 8-bit grayscale camera system was used, the data range is 0-255 (0 represents black or low residue and 255 represents white or high residue). These values are relative product rankings based on the grayscale values (lightness or darkness) of the sample residue. In the table above, 0-140 is considered low residue, 140 to 200 is medium residue and 200 and above is high residue. [0054] Sample 1, the Citrus Tea Oil + Buffer Nanoemulsion contained about 0.25% by weight of citrus tea essential oil, about 1.5% by weight Tween 20, sufficient potassium citrate buffer to bring the composition to a pH of 7.2 and the balance of the composition was water. Sample 2, the Orange Oil Nanoemulsion had a pH of 5.9 and was made up of about 0.25% by weight of orange essential oil, about 1.5% by weight Tween 20, and the balance of the composition was water. Both the Samples 1 and 2 of the present invention showed low residue levels on both the bacon grease and the cleaner. In comparison, the other natural cleaners, samples 3, 4 and 5, none of the other natural cleaners showed low residue both for the cleaner and the bacon grease residue. Sample 3, the Natrics Natural All-Purpose Cleaner had a low residue level for the cleaner but for the bacon grease residue the residue had a medium level performance which shows that the cleaners of the present invention have superior residue performance. Samples 4 and 5, the other natural cleaners, Planet All-Purpose Spray Cleaner and Amilya's Soapworks™ All-Purpose Cleaner Concentrate Performance had high residue levels in both categories, which demonstrates that the cleaners of the present invention provide superior performance over other natural cleaners currently on the market. In fact, the residue performance of the inventive compositions was comparable to that of the non-natural control cleaner, Sample 6, Formula 409® Cleaner/Degreaser which was used in the testing as standard for good residue performance.

Table 2: Concentrate Testing

The aqueous cleaning composition, in the form of a NSSL, was prepared in both a concentrated solution and a dilute solution, as follows:

[0055] The samples of the concentrated and dilute nanoemulsion cleaning composition, shown above, and concentrated and diluted samples of the Original Pine-Sol® Brand Cleaner sold by The Clorox Company were given to expert odor panelists for evaluation. The Original Pine-Sol® Brand Cleaner sold by The Clorox Company has a pH of about 3.8 and contains about 15% by weight of pine oil. The dilute solution of the Original Pine-Sol® Brand Cleaner was prepared as a 1 :64 dilution with water.

[0056] The concentrated and dilute solutions were given to expert odor panelists for odor intensity evaluation. The panelist concluded that the concentrated nanoemulsion composition which has 6.5% of pine oil had a comparable odor intensity to that of the Original Pine-Sol® Brand Cleaner which has 15% of pine oil. Similarly, the panelist found that the dilute nanoemulsion composition has a comparable odor intensity to that of the dilute Original Pine-Sol® Brand Cleaner. Based on these results, is appears that less fragrance is necessary in the nanoemulsion composition to achieve the same odor intensity which represents a significant cost savings as compared with the Original Pine- Sol® Brand Cleaner. In addition, the nanoemulsion cleaning composition has the benefit of a substantially neutral pH, a good cleaning profile with low residue and a noticable shine to the surface being cleaned.

[0057] Other suitable examples of the above concentrated nanoemulsion, include but are not limited to, compositions comprising: about 4 to 10% pine oil, 10 to 20% nonionic surfactant, more than 60% water, optionally 0 to 5% isopropanol; optionally 0 to 10% propylene glycol, optionally 0 to 10% glycerin, and optionally 0 to 10% propanediol. Preferred embodiments of the concentrated nanoemulsion comprise about 5 to 7% pine oil and 13 to 16% of nonionic food safe surfactants. All of the suitable examples of the concentrated nanoemulsion cleaning compositions have a pH in the range of 6 to 8.

[0058] The cleaning composition of the present invention may be used in neat (undiluted) form or it can be diluted, for example, with up to about 99% water, depending on the involved cleaning application. In its diluted form, the clean composition still retains the significant advantages of cleaning efficiency combined with low residue and intense fragrance profile. The ability to dilute the present invention to a composition which can, for example, comprise as little as 1% composition of the present invention and as much as 99% water offers an additional economic advantage, as water is the least costly ingredient in the cleaning composition.

Equilibrium Contact Angle Testing

[0059] The equilibrium contact angle measures the wetting of a solid by a liquid. It is the angle formed by the liquid at the three-phase boundary where a liquid, gas (or a second immiscible liquid) and solid intersect. Equilibrium contact angle was measured by the observation of drops of test liquid on a clean glass slide using a digital video camera. For each sample composition, two slides are prepared with seven droplets of test liquid on each slide. Then the test droplets are observed using the digital video camera until the droplet reaches equilibrium and there is no visible change in the droplet shape, which is usually about 30 seconds to 1 minute. The equilibrium contact angle is then determined by drawing a tangent at the contact point where the liquid and the solid intersect. [0060] The cleaning composition of the present invention tested for equilibrium contact angle contained about 0.25% essential oil by weight, about 1 % ethanol by weight, about 1.5% Tween 20 by weight and the balance water. The equilibrium contact angle was measured at about 6.2 degrees plus or minus 1.2 degrees. For comparison purposes, the equilibrium contact angle of water was also measured to be about 12.6 degrees plus or minus 1.7 degrees. The relatively low contact angle of the cleaning composition of the present invention, show that the cleaning composition achieves good, uniform surface coverage and wettablity . The wettablity and surface coverage of a cleaner are important because they can enhance the effectiveness of the cleaner by increasing the contact area of the cleaner and the surface being cleaned. In addition, a low contact angle is also indicates that the cleaning composition has good dispersion and uniformity across a surface which is critical to achieving low residue levels.

Video, Still-Microphotography and FTIR Mapping

[0061] The first test sample was made up of George Foreman Knock-Out™ Multipurpose Cleaner. The second test sample is a nanoemulsion comprising: 1.5% Tween 80, 1.0% Dowfax 2Al, 0.08% propylene glycol, 0.25% tea tree citrus oil, and the balance water. The third test sample is a nanoemulsion comprising: 0.25% essential oil, 0.25% ethanol, 1.5% Tween 20 and 98% water. Each of the test samples was placed by pipette on a thin, flat polished silicon wafer with a three-inch circular diameter. Each test sample was tested in triplicate. The surface of the silicon wafer is oxidized to provide a good model for glass and ceramic surfaces. The droplet volumes were 0.2ul for the low power microphotography, but droplets of up to 0.5ul were also examined and displayed similar drying behavior. Digilab Shadow software and TechSmith Camtasia software were used for recording the videos of the droplets drying. Still pictures were taken of the droplets using the TechSmith Snaglt software. The fields of view for the photomicrography were about 2.0 to 2.5mm.

[0062] Figure 1 shows the drying behavior of the George Foreman Knock-Out™ Multipurpose Cleaner. Figure Ia shows the initial droplet of the George Foreman cleaning composition on the silicon wafer surface. Figures Ib shows the droplet after 2 seconds on the silicon wafer surface. Figure Ic shows the droplet after 4 seconds on the silicon wafer surface. Figure Id shows the dried droplet of the George Foreman cleaning composition on the surface. In Figures Ib and Ic, the George Forman cleaner shows solids building up at the edge of the original footprint of the droplet as it begins to dry. The solids build up at the lower left edge of the droplet and indicate there is phase separation between the solids and liquid of the composition as it dries. The solids create a raised rim at the lower left-hand edge of the droplet and speed up the evaporation process by increasing the liquid to air surface area. In Figure Id, the dried composition contains a visible and unattractive edge with solid build up and also discrete regions within the interior of the droplet where clumps of solids are dried together. As shown in Figure Id, the solid residues left behind on the surface of the silicon wafer are clearly visible in the lower left hand edge of the droplet and also in clumps in the interior portion of the dried droplet.

[0063] Figure 2 shows the drying behavior of the nanoemulsion cleaning compositions of the present invention. Since the droplet drying behavior for both the nanoemulsion test samples, samples two and three, had the same characteristics, only the pictures of sample two are included to represent both droplets. Figure 2a shows the initial droplet of the test sample two nanoemulsion cleaning composition on the silicon wafer surface. Figures 2b shows the droplet after 2 seconds on the silicon wafer surface. Figure 2c shows the droplet after 4 seconds on the silicon wafer surface. Figure 2d shows the dried droplet of the test sample two nanoemulsion cleaning composition on the surface. The droplet has a low contact angle and maintains a low contact angle as the wetting edge recedes when the droplet dries. The droplet creates and initial footprint on the silicon wafer surface and as the droplet dries the dried solids continuously span the original footprint. Since there is uniform distribution of the solids as the droplet dries the solids are not readily visible on the surface and there essentially no evidence of phase separation, as shown in Figure 2d.

Fourier Transform Infrared Spectroscopy

[0064] Fourier Transform Infrared Spectroscopy was performed on the dried samples of the shown in Figures 1 and 2. The FTIR testing was done on segments of the sample to determine the distribution of the residue across the footprint of the dried droplets. Liquid test material droplets were placed on polished stainless steel tiles of about 4 x 4 inches and air dried. Due to the high magnification needed for FTIR mapping, small volume droplets of about 0.2 ul were used. The FTIR mapping of the George Forman Knock- Out™ Multi-Purpose Cleaner showed large peaks Of CH₂ and COO-, which correspond to the solid residue visible at the lower left hand edge of the droplet. The FTIR mapping of the George Foreman sample confirms that there is significant residue along the edge of the droplet footprint and evidence of phase separation. The FTIR mapping of the nanoemulsion cleaning compositions of the present invention showed an essentially uniform distribution of residue across the footprint of the dried droplet. Sample two nanoemlusion showed some minor peaks of CH₂ and C=O from Tween 80 and a peak for Dowfax 2Al . The sample three nanoemulsion only had CH₂ and C=O from Tween 80 because there was no Dowfax 2Al in sample three. The FTIR testing of the nanoemulsion cleaning samples confirms that there is essentially no evidence of phase separation and the residue for the nanoemulsions is spread out over relatively evenly across the footprint of the droplets

[0065] While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to these embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

IN THE CLAIMS

1. A cleaning composition in the form of a nanoemulsion comprising:

(a) a food safe nonionic surfactant; (b) a solvent selected from the group consisting of: propylene glycol, glycerin, isopropanol, 1,3-propanediol, and mixtures thereof; (c) an essential oil; and (d) water wherein the cleaning composition has a pH of about 6 to 8 and there is at least a 2:1 ratio of nonionic surfactant to essential oil.

2. The cleaning composition of claim 1 wherein the food safe surfactant comprises an alkyl polyglycoside.

3. The cleaning composition of claim 1 wherein the nanoemulsion has a particle size of 50 nm or less.

4. The cleaning composition of claim 1 wherein the food safe nonionic surfactant has an HLB value of at least 10.

5. The cleaning composition of claim 1 wherein the food safe nonionic surfactant has an HLB value of at least 13.

6. The cleaning composition of claim 1 wherein the cleaning composition has an equilibrium contact angle of less than about 10 degrees.

7. The cleaning composition of claim 1 wherein the food safe nonionic surfactant is a polysorbate.

8. The cleaning composition of claim 2 wherein the cleaning composition contains at least 0.5% of alkyl polyglycoside by weight.

9. A cleaning composition in the form of a nanoemulsion comprising: (a) a glycoside surfactant; (b) an essential oil; (c) an organic solvent selected from the group consisting of: propylene glycol, glycerin, isopropanol, 1,3 -propanediol, and mixtures thereof; and (d) water; wherein the cleaning composition has a pH of about 6 to 8 and there is at least 2:1 ratio of nonionic surfactant to essential oil.

10. The cleaning composition of claim 9 wherein the glycoside surfactant is a C8-C10 alkyl polyglycoside.

11. The cleaning composition of claim 9 wherein the organic solvent comprises a propylene glycol.

12. The cleaning composition of claim 9 wherein the wherein the organic solvent comprises a glycerin.

13. The cleaning composition of claim 9 wherein the organic solvent comprises a 1,3- propanediol.

14. The cleaning composition of claim 9 wherein the cleaning composition further comprises a sulfonate surfactant.

15. The cleaning composition of claim 9 wherein the cleaning composition is has an equilibrium contact angle of less than 10 degrees.

16. The cleaning composition of claim 9 wherein the cleaning composition is essentially free of monohydric alcohols.

17. A cleaning composition in the form of a nanoemulsion consisting essentially of: (a) an alkyl polyglycoside surfactant; (b) an essential oil; (c) a solvent selected from the group consisting of: propylene glycol, 1,3- propanediol, glycerin, and combinations thereof; and (d) water; wherein the cleaning composition has a pH of about 6 to 8 and a heat of dissolution of about 10° F to 30° F.

18. The cleaning composition of claim 17 wherein the cleaning composition comprises at least 0.75% of alkyl polyglycoside by weight.

19. The cleaning composition of claim 17 wherein the solvent comprises a propylene glycol.

20. The cleaning composition of claim 17 wherein there is at least a 4:1 ratio of alkyl polyglycoside surfactant to essential oil.