BACKGROUND Perborate bleach is a common bleach source for cleaning compositions to bleach fabrics and other substrates. When dissolved in aqueous solution, a perborate bleach generates hydrogen peroxide which provides a bleaching activity by oxidizing the substrate. The bleaching activity is proportional to the amount of hydrogen peroxide produced, and provides the cleaning composition with, for example, improved whitening and cleaning power. Perborate bleach is especially preferred in laundry compositions, as it tends not to damage colored fabrics.

However, perborate bleach suffers from stability problems due to reactions with certain outside agents. For example, a perborate bleach may degrade when exposed to even small amounts of water, such as humidity encountered during storage. When perborate is exposed to water, it first forms hydrogen peroxide. Hydrogen peroxide is thermodynamically unstable and decomposes into water and oxygen gas. This water formation initiates a cascade reaction which further increases the decomposition rate of perborate into hydrogen peroxide and the formation of more water. Alkaline conditions catalyze this decomposition reaction, as well as the initial formation of hydrogen peroxide by perborate. The decomposition reaction of hydrogen peroxide is:

Alkalinity catalyzes the forward reaction, depleting the hydrogen peroxide and forming water. This further promotes perborate dissolution and the release of hydrogen peroxide. When these reactions occur during storage, they reduce the amount of perborate available as a bleaching agent during cleaning. Therefore, it is desirable to enhance perborate bleach stability by preventing the perborate from degrading during storage, and yet allow it to form hydrogen peroxide during cleaning.

Furthermore, a perborate bleach may react with other outside agents, such as enzymes, amido-surfactants, amine-containing chelants, polymers, etc.

For example, certain polymers may react with perborate to form cross-linked polymers ; fatty acids may be oxidized into polymerized lipids. Dyes may also be oxidized by the perborate bleach, and lose their color. These reactive ingredients may also degrade the perborate bleach, or otherwise bind to it, reducing the amount of hydrogen peroxide produced during cleaning.

Accordingly, it is desirable to enhance perborate bleach stability by preventing the perborate bleach from reacting with other ingredients. These perborate bleach stability problems may also lead to a limited shelf life for perborate- containing cleaning compositions.

In certain detergent forms, such as in a tablet or in a laundry detergent bar, the degradation of a perborate bleach may be increased due to the form itself. As opposed to in, for example, a granular detergent, an uncoated perborate bleach in such a contiguous matrix may be in intimate contact with many such reactive outside agents, and especially water. Thus, it is desirable to protect a perborate bleach from degradation in conditions which are specific to such physical cleaning composition forms.

To prevent such degradation, a perborate bleach is typically coated with a protective coating. Typical coatings include waxes, surfactants, and inert materials. These coating layers typically act as physical barriers which reduce the likelihood that an outside agent will react with a component of the core particle. However, such a protective coating may protect the perborate bleach too well, and not"release"it to allow formation of hydrogen peroxide in certain wash conditions. For example, a waxy coating layer may depend upon temperature to melt the coating layer and thereby release the core particle for cleaning ; however, in cold cleaning conditions, such as in hand-wash conditions, the water temperature may not be high enough to melt the wax and release the

core particle into solution. Thus, the active component of the core particle, e. g., a perborate bleach, is unable to provide a cleaning activity. Alternatively, the protective coating may bind too tightly to the perborate and may thereby actually decrease such hydrogen peroxide formation in solution.

Accordingly, the need remains for a coating layer which prevents a perborate bleach from degrading during storage, and yet allows the perborate bleach to form hydrogen peroxide in aqueous solution.

SUMMARY This need is met by the present invention, wherein it has now been found that a coated perborate particle may possess improved protection against outside agents such as water, while allowing the perborate bleach contained therein to easily form hydrogen peroxide in solution. Accordingly, the present invention relates to an improved coated bleach particle which contains a core particle and a coating layer. The core particle contains therein a perborate bleach, while the coating layer contains a water-soluble boron compound and an acid source. In the improved coated bleach particle, the molar ratio of the water- soluble boron compound to the perborate bleach is from about 5: 1 to about 1: 100, while the ratio of the water-soluble boron compound to the acid source is from about 1: 19 to about 19: 1.

According to another embodiment of the present invention, the improved coated bleach particle contains a core particle and a coating layer. The core particle contains therein a perborate bleach, while the coating layer contains a water-soluble boric acid. In this improved coated bleach particle, the molar ratio of the water-soluble boric acid to the perborate bleach is from about 5: 1 to about 1: 100.

Also described herein are cleaning compositions containing the coated bleach particle of the present invention.

These and other features, aspects, and advantages of the present invention will become evident to those skilled in the art from a reading of the present disclosure with the appended claims.

DETAILED DESCRIPTION In accordance with the present invention it has now been found that outside agents such as water, alkalinity, and, reactive ingredients degrade the

stability of perborate bleach. Accordingly, the coated bleach particle of the invention reduces exposure of the perborate bleach to such outside agents during storage in order to significantly enhance perborate bleach stability.

However, the present invention allows the perborate bleach to form hydrogen peroxide in solution, even under cold wash conditions. Furthermore, in granular cleaning compositions, the coating layer described herein reduces caking. When incorporated into a solid matrix, such as a detergent bar and tablet, the present invention also protects the bleach from prematurely reacting with outside agents.

All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (°C) unless otherwise specified. All documents cited are incorporated herein by reference.

As used herein, the term"alkyl"means a hydrocarbyl moiety which is straight or branched, saturated or unsaturated. Unless otherwise specified, alkyl moieties are preferably saturated or unsaturated with double bonds, preferably with one or two double bonds. Included in the term"alkyl"is the alkyl portion of acyl groups.

The coated bleach particle of the invention contains a coating layer which provides a core particle with both physical and chemical protection from outside agents such as water, alkalinity, and reactive ingredients. Without intending to be limited by theory, it is believed that improved stability results from the synergistic combination of a water-soluble boron compound and an acid source in the coating layer. Furthermore, the coating layer of the present invention allows the perborate bleach to provide bleaching activity when used for cleaning, even in cold wash conditions.

In the present invention, the coating layer first serves as a physical barrier which coats the core particle and thereby reduces the amount of water, alkalinity, or reactive ingredients which reach the core particle. For example, the water- soluble boron compound will absorb small amounts of water and/or react with reactive ingredients before they reach the perborate bleach within the core particle. Similarly, the acid source in the coating layer neutralizes alkaline compounds before they reach the perborate bleach within the core particle. This effect is especially prominent when the coated bleach particle of the present invention is incorporated into a solid matrix, such as a detergent bar and tablet.

Furthermore, because the boron compound and the acid source of the coating layer are water-soluble, they easily dissociate from the perborate bleach in

solution. Accordingly, the coating layer of the present invention easily releases the perborate bleach, even in cold-wash conditions, so that it may provide a bleaching activity.

The coating layer also acts as a chemical barrier against perborate degradation caused by water, alkalinity, and reactive ingredients. For example, the present invention recognizes that the addition of a common ion to the coating layer reduces the solubility of the perborate bleach, and results in a coated bleach particle having improved perborate bleach stability. Without intending to be limited by theory, it is believed that the water-soluble boron compound reduces the solubility of the perborate bleach when small amounts of water are encountered (e. g., humidity encountered during storage). This is believed to occur via a concentration-dependent"common-ion effect,"where the formation of hydrogen peroxide by perborate and water is driven in reverse by providing an excess of a common ion. For example, a salt, BX, that dissolves in water into B+ and X-, has a given dissociation constant, KD therefore, the stoichiometric equation is represented as: (Formula I) where Kp is a constant, and may be represented as: <BR> <BR> Ko= fBirXI (Formuta !))<BR> [BX] The dissociation of BX may be driven to the left by increasing the concentration of either species B+ and/or X-.

In the present invention, the perborate bleach is represented by BX, while a dissolved water-soluble boron compound represents B+. Accordingly, it is believed that when such a water-soluble boron compound drives the stoichiometry to the left, the solubility of the perborate bleach is reduced, which in turn, significantly reduces the degradation of perborate into hydrogen peroxide during storage. This in turn reduces degradation of the perborate bleach and enhances its storage stability.

The present invention also recognizes that alkalinity-catalyzed degradation plays a significant role in decreasing perborate bleach stability. It has now been found that even small amounts of alkalinity are detrimental to perborate bleach stability. Without intending to be limited by theory, it is believed that alkaline conditions promote the degradation of the perborate into hydrogen peroxide, as well as the degradation of hydrogen peroxide into water and oxygen

gas. Accordingly, the coating layer of the present invention comprises an acid source to neutralize alkalinity before it reaches and degrades the perborate.

Furthermore, the present invention recognizes that storage conditions and in-use conditions are significantly different. The present invention takes advantage of these differences to provide the core with improved protection from outside agents during storage. For example, the amount of water encountered during storage (e. g., humidity) is typically much less than that encountered when the coated bleach particle is used in solution. In cases where only a small amount of water is present to degrade the perborate, the common-ion effect is enhanced, because the local concentration of each species is significantly higher. Furthermore, because the water-soluble boron compound is employed in a coating layer around the perborate bleach, outside water will first encounter the water-soluble boron compound. Therefore, any water which reaches the perborate bleach already has an amount of boron compound dissolved therein.

Accordingly, even a relatively small amount of water-soluble boron compound surrounding the core particle may provide a high enough concentration of common-ion (s) to reduce the solubility (and therefore the degradation) of the perborate bleach during storage. Similarly, the effect of the acid source in the coating layer is amplifie when only a small amount of water is present.

However, in-use (e. g., cleaning) conditions are significantly different, because water tends to be present in great excess. In conditions where water is at great excess, the common-ion effect is negligible. Accordingly, during use, the presence of the water-soluble boron compound in solution does not significantly reduce the solubility of the perborate bleach.

It is also befieved that because the water-soluble boron compound surrounds the perborate bleach, the water-soluble boron compound has a water- scavenging effect. In an embodiment of the present invention, the water-soluble boron compound has a high affinity for water, and therefore"grabs"it before it reaches the perborate bleach. This is especially true if the water-soluble boron compound has a greater affinity for water than does the perborate bleach. This water-scavenging effect reduces initiation of the cascade effect and thereby improves the stability of the perborate bleach. Because less water is absorbed by the core particle and less water is formed, this also results in reduced caking of granular cleaning compositions.

Accordingly, the coated bleach particle of the invention possesses improved protection from outside agents, while maintaining effective bleaching activity during use.

Coated Bleach Particle The coated bleach particle of the present invention contains a core particle and a coating layer which protects the core particle from outside agents. The coated bleach particle provides a bleaching activity when used for cleaning. The coated bleach particle is suitable for use either alone, or in conjunction with at least one adjunct ingredient, in a cleaning composition. The coated bleach particle is applicable to a variety of cleaning compositions, such as for example, hard surface cleaning, laundry applications, disinfecting compositions, and cleaning gels, pastes, and liquids. In a preferred embodiment, the coated bleach particle may be used in a laundry composition, especially compositions which possess little inherent water, such as a granular composition, a tablet, and a laundry detergent bar composition. More preferably, the coated bleach particle may be used in a solid composition, such as a tablet, and a laundry detergent bar composition.

The coated bleach particle of the present composition will typically be less than about 1000 microns in diameter, preferably between about 200 microns and about 900 microns in diameter, and more preferably between about 300 microns and about 700 microns in diameter. The coated bleach particle of the present composition will typically comprise from about 0.1% to about 100%, preferably from about 0.5% to about 30%, and more preferably from about 1% to about 20% of the cleaning composition, by weight.

Core Particle The coated bleach particle of the present invention comprises a core particle which contains a perborate bleach. The core particle may also contain at least one adjunct ingredient. The core particle useful herein is solid, semi-solid, or even a gel, but is preferably a solid. The core particle may be produced by methods known in the art, for example, spray drying, agglomeration, etc. Before being coated, the core particle will typically be less than about 1000 microns in diameter, preferably between about 200 microns and about 800 microns in

diameter, and more preferably between about 300 microns and about 600 microns in diameter.

The perborate bleach useful herein is an oxygen bleach which reacts with water to deliver"available oxygen" (AvO) or"active oxygen"which is typically measurable by standard methods such as iodide/thiosulfate and/or ceric sulfate titration. See the well-known work by Swern, or Kirk Othmer's Encyclopedia of Chemical Technology under"Bleaching Agents". When the oxygen bleach is a peroxygen compound, it contains-O-O-linkages with one O in each such linkage being"active". The AvO content of such an oxygen bleach compound, usually expressed as a percent, is equal to 100 * the number of active oxygen atoms * (16/molecular weight of the oxygen bleach compound). In the case of a perborate bleach, the active oxygen is delivered in the form of hydrogen peroxide.

The preferred perborate bleach useful herein is selected from the alkali metal perborate bleaches, with the sodium, and potassium perborate bleaches being more preferred. Specific, preferred examples of the perborate bleach useful herein include the sodium and potassium salts of super perborate (e. g., NaBO3 ; anhydrous sodium perborate), perborate monohydrate (e. g., NaBO2 H202), perborate tetrahydrate (e. g., NaB02-3H20-H202), and mixtures thereof.

Such perborate bleaches are commercially available from, for example, E.

I. du Pont de Nemours and Company (Wilmington, DE, USA), Elf Atochem North America, Inc. (Philadelphia, PA, USA), Degussa (Hanau, Germany), Solvay Interox (Brussels, Belgium), Mitsubishi Gas Chemical Company, Inc. (Tokyo, Japan), Eka Nobel AB (Bohus, Sweden), etc.

The perborate bleach will typically comprise from about 10% to about 100%, preferably from about 50% to about 100%, and more preferably from about 70% to about 100% of the core particle, by weight.

In addition to the perborate bleach, the core particle may further contain at least one adjunct ingredient which is protected by the coating layer. Nonlimiting examples of an adjunct ingredient useful in the core particle herein include an additional bleach, a bleach activator, an enzyme, a filler, and mixtures thereof.

The additional bleach useful herein also has a bleaching activity when used in a cleaning composition, and includes an additional (non-perborate) oxygen bleach, a reducing bleach, a chlorine bleach, a photobleach, a bleach

activator, and mixtures thereof. The additional oxygen bleach useful in the present invention may be any of the oxidizing agents known for laundry, hard surface cleaning, automatic dishwashing or denture cleaning purposes. The additional oxygen bleach may include, for example, a peroxygen compound, a peracid, an enzymatic source of hydrogen peroxide, and mixtures thereof. A hypohalite such as a chlorine bleach like hypochlorite, may also be used herein.

A preferred additional bleach includes a percarbonate, a peracid, hydrogen peroxide, an oxidase, a pesait, and mixtures thereof. Moreover, it is preferred that the additional bleach be highly soluble in water.

The bleach activator useful herein has an activity which increases or promotes a bleach's bleaching activity, and includes an amide, an imide, an ester, an anhydride, and mixtures thereof. Typically, at least one substituted or unsubstituted acyl moiety is present, covalently connected to a leaving group as in the structure R-C (O)-L, where L denotes a leaving group. A preferred bleach activator is a peroxygen bleach activator.

Preferred bleach activators include N, N, N'N'-tetraacetyl ethylene diamine (TAED) or any of its close relatives including the triacetyl or other unsymmetrical derivatives. TAED and the acetylated carbohydrates such as glucose pentaacetate and tetraacetyl xylose are preferred hydrophilic bleach activators.

Depending on the application, acetyl triethyl citrate, a liquid, also has some utility, as does phenyl benzoate.

Preferred hydrophobic bleach activators include sodium nonanoyloxybenzene sulfonate (NOBS or SNOBS), substituted amide types described in detail hereinafter, such as activators related to 6-nonylamino-6- oxoperoxycaproic acid (NAPAA) as described in U. S. Patent 4,634,551 to Hardy and Ingram, issued January 6, 1987, and activators related to certain imidoperacid bleaches, for example as described in U. S. Patent 5,061,807 to Gethoffer, et al., issued October 29,1991 and assigned to Hoechst Aktiengesellschaft of Frankfurt, Germany. Japanese Laid-Open Patent Application (Kokai) No. 4-28799 to Yamada, et al., published January 31,1992 for example describes a bleaching agent and a bleaching detergent composition comprising an organic peracid precursor described by a general formula and illustrated by compounds which may be summarized more particularly as conforming to the formula:

wherein L is sodium p-phenolsulfonate, R1 is CH3 or C12H25 and R2 is H.

Analogs of these compounds having any of the leaving-groups identified herein and/or having R1 being linear or branched C6-C16 are also useful.

Other suitable bleach activators include sodium-4-benzoyloxy benzene sulfonate (SBOBS); sodium-1-methyl-2-benzoyloxy benzene-4-sulphonate ; sodium4-methyl-3-benzoyloxy benzoate (SPCC); trimethyl ammonium toluyloxy-benzene sulfonate ; or sodium 3,5,5-trimethyl hexanoyloxybenzene sulfonate (STHOBS).

The enzyme useful herein has an enzymatic activity, and includes an amylase, a cellulase, a cutinase, a lipase, a peroxidase, a protease, and mixtures thereof. Amylases are particularly suitable for automatic dishwashing purposes.

An amylase useful herein includes, for example,-amylases described in GB 1,296,839 to Outtrup H, et al., published November 22,1972 to Novo Industries A/S of Denmark (hereinafter,"Novo") ; RAPIDASES) from International Bio- Synthetics, Inc. ; TERMAMYL@from Novo Novo and and FUNGAMYLO from Cellulases usable herein include both bacterial and fungal types, preferably having a pH optimum between 5 and 9.5. U. S. 4,435,307, to Barbesgoard, et al., March 6,1984, discloses suitable fungal cellulases from Humicola insolens or Humicola strain DSM1800 or a cellulase 212-producing fungus belonging to the genus Aeromonas, and cellulase extracted from the hepatopancreas of a marine mollusk, Dolabella Auricula Solander. Suitable cellulases are also disclosed in GB-B-2,075,028 to Barbesgaar, et al., issued March 28,1984; GB-B-2,095,275 to Murata, et al., issued August 7,1985 and DE-OS-2,247,832 to Horikoshi and Ikeda, issued June 27 1974. CAREZYMEO and CELLUZYMES (Novo) are especially useful. See also WO 91/17243 to Hagen, et al., published November 14,1991.

Cutinase enzymes suitable for use herein are described in WO 88/09367A to Kolattukudy, et al., published December 1,1988.

Suitable lipase enzymes for detergent usage include those produced by microorganisms of the Pseudomonas group, such as Pseudomonas stutzeri ATCC 19.154, as disclosed in GB 1,372,034 to Dijk and Berg, published October 30,1974. See also lipases in Japanese Patent Application 53-20487 to Inugai, published February 24,1978. This lipase is available from Amano Pharmaceutical Co., Ltd., Nagoya, Japan, under the trade name Lipase P "Amano,"or"Amano-P."Other suitable commercial lipases include Amano-CES, lipases ex Chromobacter viscosum, e. g. Chromobacter viscosum var. lipolyticum NRRLB 3673 from Toyo Jozo Co., Tagata, Japan; Chromobacter viscosum lipases from U. S. Biochemical Corp., U. S. A. and Disoynth Co., the Netherlands, and lipases ex Pseudomonas gladioli. LIPOLASEO, from Novo, is a preferred lipase for use herein. LIPOLASEO is derived from Humicola lanuginosa, see also EP 341,947 to Cornelissen, et al., issued August 31,1994. Lipase and amylase variants stabilized against peroxidase enzymes are described in WO 94/14951 to Halkier, et al., published July 7,1994 A to Novo. See also WO 92/05249 to Clausen, et al., published April 2,1992.

Peroxidase enzymes may be used in combination with any oxygen bleach, e. g., percarbonate, perborate, hydrogen peroxide, etc., for"solution bleaching"or prevention of transfer of dyes or pigments removed from substrates during the wash to other substrates present in the wash solution. Known peroxidases include horseradish peroxidase, ligninase, and haloperoxidases such as chloro- or bromo-peroxidase. Peroxidase-containing detergent compositions are disclosed in WO 89/09813 A to Damhus, et al., published October 19,1989.

A suitable example of a protease is a subtilisin, which is obtained from particular strains of B. subtilis and B. licheniformis. One suitable protease is obtained from a strain of Bacillus, having maximum activity throughout the pH range of 8-12, developed and sold as ESPERASE@ by Novo. Other examples of a suitable protease includes ALCALASEO and SAVINASE from Novo and MAXATASEO from International Bio-Synthetics, Inc., the Netherlands ; as well as Protease A and Protease B as disclosed in EP 130,756 A to Bott, published January 9,1985. An especially preferred protease, referred to as"Protease D," as described in U. S. Patent 5, 679,630 to A. Baeck, et al, issued October 21, 1997, entitled"Protease-Containing Cleaning Compositions,"and U. S. Patent 5,677,272 to C. Ghosh, et al, issued October 14, 1997, entitled"Bleaching Compositions Comprising Protease Enzymes."

The filler useful herein may be an inert compound upon which a liquid is absorbed. However, the filler useful herein may also serve an additional purpose, such as for example, enhancing particle dissolution or providing a buffering effect. Preferred examples of the filler useful herein includes organic and inorganic materials such as talc, and builders such as alkali metal carbonates, alkali metal phosphates, alkali metal sulfates, and mixtures thereof.

Coating Layer The core particle is coated with a coating layer which comprises a water- soluble boron compound and an acid source. In a preferred embodiment, the water-soluble compound and the acid source are intimately mixed prior to coating the core particle. In order to provide optimum protection, a highly preferred coating layer substantially coats the entire surface of the core particle. The core particle is coated with at least one, and preferably multiple coating layers comprising a water-soluble boron compound and an acid source. While it is possible, for example, to provide a coating layer comprising an acid source and a separate coating layer comprising a water-soluble boron compound (either inside or outside of the acid source coating layer), it is preferred in the present invention that the water-soluble boron compound and the acid source be present in a single layer. Such a single layer is more economical and easier to apply.

The typical weight ratio of core particle to coating layer is from about 200: 1 to about 1: 3, preferably from about 20: 1 to about 1: 1, and more preferably from about 10: 1 to about 2: 1.

The coated bleach particle may further comprise other coating layers, either inside of, or outside of the coating layer which contains the water-soluble boron compound and the acid source. To prevent caking, tackiness, and/or clumping during storage and/or in the final product, a coated bleach particle is often"dusted"or coated with a fine powder, such as zeolite. If present, this would comprise the outermost coating layer.

The coating layer of the present invention comprises therein at least one water-soluble boron compound. The water-soluble boron compound serves to, for example, dissolve to provide the common-ion effect, act as a water- scavenger, react with a reactive ingredient before it reaches the perborate bleach, etc. The boron compound useful herein is water-soluble, having a solubility of at least 0.1 g/L at 20 °C.

To provide a significant common-ion effect, the water-soluble boron compound must dissolve in solution to provide a borate ion, B (OH) 4-', and preferably boric acid, which serves the dual purpose of simultaneously providing a common ion and neutralizing alkalinity. As discussed above, by providing a common ion, the coating layer provides additional protection to the perborate bleach. The water-soluble boron compound useful herein includes a borate-diol, a boric acid, borax, a borosilicate, and mixtures thereof. The water-soluble boron compound is preferably boric acid, a borate, and mixtures thereof. The alkali metal and alkali earth metal salts of these water-soluble boron compounds are highly preferred.

The acid source useful herein provides an acidic barrier which prevents alkalinity from reaching and degrading the perborate bleach. If dissolved in deionized water, the pH of a 1 % solution of the coating layer should be less than about 6, preferably between about 4, and about 6, and more preferably between about 4.5, and about 5.5. The acid source useful herein is preferably a small- chain polyprotic acid, or more preferably citric acid, maleic acid, malic acid, boric acid, and mixtures thereof.

The molar ratio of the water-soluble boron compound to the perborate bleach is from about 5: 1 to about 1: 100, preferably from about 5: 3 to about 1: 50, and more preferably from about 1: 1 to about 1: 10. Furthermore, the weight ratio of the water-soluble boron compound to the acid source useful in the coating layer herein is from about 1: 19 to about 19: 1, preferably from about 4: 1 to 3: 7, and more preferably from about 3: 2 to about 1: 1.

In a preferred embodiment herein, the water-soluble boron-compound and the acid source are one and the same, such as, a water-soluble boric acid. In this embodiment, the molar ratio of the water-soluble boric acid to the perborate bleach is from about 5: 1 to about 1: 100, preferably from about 5: 3 to about 1: 50, and more preferably from about 1: 1 to about 1: 10. The molar ratios described herein assume that each molecule of water-soluble boric acid molecule liberates one borate ion in solution. If, for example, each water-soluble boric acid molecule liberates two borate ions in solution, then the molar ratios described herein may be adjusted accordingly.

The coating layer may further contain an adjunct ingredient, such as those commonly used to coat a particle. Non-limiting examples of such an adjunct ingredient include a surfactant, a wax, a polymer, fatty acids, and mixtures

thereof. If present, this adjunct ingredient will typically comprise from about 0.1% to about 30% of the coating layer, by weight.

Cleaning Composition The coated bleach particle of the present invention is useful either alone, or in conjunction with an adjunct ingredient as a cleaning composition. As noted above, the cleaning composition may be applicable to, for example, personal cleansing, hard surface cleaning, fabric laundering, manual or automatic dishwashing, and other cleaning applications. Any of the adjunct ingredients described above in the core particle and/or the coating layer may also be included as an adjunct ingredient in the cleaning composition.

A cleaning composition, such as a preferred granular or solid cleaning composition, typically contains at least one adjunct ingredient. In a cleaning composition, a preferred example of a typical adjunct ingredient is a detersive surfactant, such as amphoteric surfactant, anionic surfactant, nonionic surfactant, zwitterionic surfactant, and mixtures thereof. In a preferred embodiment, the adjunct coating material includes both a nonionic surfactant and an anionic surfactant.

If desired, the conventional nonionic and amphoteric surfactants such as the C12-Cg alkyl ethoxylates ("AE") including the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C12-C1g betaines and sulfobetaines ("sultaines"), and the like, may also be included as an adjunct coating material in the coating layer.

A preferred amphoteric surfactant for use herein includes betaines, glycinates, amino/amido propionates, imidazoline-based amphoterics, and mixtures thereof.

A preferred nonionic surfactant for use herein includes alkyl ethoxylates, alkyl substituted with phosphine oxides, sulphoxides, and mixtures thereof.

A preferred anionic surfactant for use herein includes a fatty acid, a soap, alkyl sulfates, sulfonates, and mixtures thereof. A more preferred anionic surfactant useful herein includes the C10-C1g amine oxides, the conventional Cn1-C1g alkyl benzene sulfonates ("LAS"), the primary, branched-chain and random C10-C20 alkyl sulfates ("AS"), the Cro-C1g secondary (2,3) alkyl sulfates of the formula CH3 (CH2) x (CHOS03-M+) CH3 and CH3 (CH2) y (CHOSO3~M) CH2CH3 where x and (y + 1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilizing cation, especially

sodium, unsaturated sulfates such as oleyl sulfate, the C10-C18 alkyl alkoxy sulfates ("AEXS" ; especially EO 1-7 ethoxy sulfates), C10-C-g alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates), the C10-18 glycerol ethers, the C10-C1g alkyl polyglycosides and their corresponding sulfate polyglycosides, and C12-C1g alpha-sulfonated fatty acid esters. The Cio-Cig N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the C12-C1g N-methylglucamides. See WO 92/06154 to Cook, et al., published April 16, 1992. Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-C1g N-(3-methoxypropyl) glucamide.

The N-propyl through N-hexyl C12-C1g glucamides can be used for low sudsing.

The fatty acids useful herein are linear or branched carbon chains containing from about 8 to about 24 carbon atoms, preferably from about 10 to about 20 carbon atoms. The average carbon chain length for the fatty acid or soap is from about 12 to about 18 carbon atoms, preferably from about 14 to about 16 carbon atoms. Preferred fatty acids are obtained from coconut oil, tallow, palm oil (palm stearin oil), palm kernel oil, and mixtures thereof. Fatty acids can be synthetically prepared, for example, by the oxidation of petroleum, or by hydrogenation of carbon monoxide by the Fischer-Tropsch process.

As used herein,"soap"means salts of fatty acids. Preferred soaps are alkali metal soaps, such as sodium and potassium soaps, ammonium soaps, and alkylolammonium soaps. The soaps useful herein are preferably obtained from natural sources such as plant or animal esters; non-limiting examples include coconut oil, palm oil, palm kernel oil, olive oil, peanut oil, corn oil, sesame oil, rice bran oil, cottonseed oil, babassu oil, soybean oil, castor oil, tallow, whale oil, fish oil, grease, lard, and mixtures thereof. Alkali metal soaps can be made by direct saponification of fats and oils or by the neutralization of the free fatty acids which are prepared in a separate manufacturing process or prepared just prior to application of the coating layer.

Preferred soap raw materials useful herein are soaps made from mixtures of fatty acids from tallow and coconut oil. Typical mixtures have tallow to coconut fatty acid ratios of 85: 15,80: 20,75: 25, 70: 30,50: 50 and 0: 100; preferred ratios are from about 80: 20 to about 0: 100.

A preferred soap for use herein are neat soaps made by kettle (batch) or continuous saponification. Neat soaps typically comprise from about 65% to about 75%, preferably from about 67% to about 72%, alkali metal soap; from

about 24% to about 34%, preferably from about 27% to about 32%, water; and minor amounts, preferably less than about 1% total, of residual materials and impurities, such as alkali metal chlorides, alkali metal hydroxides, alkali metal carbonates, glycerin, and free fatty acids. Another preferred soap raw material is soap noodles or flakes, which are typically neat soap which has been dried to a water content of from about 10% to about 20%.

Other useful detersive surfactants are listed in standard texts. Preferably the cleaning composition comprises, by weight of the final composition, at least about 0.01% of a detersive surfactant; more preferably at least about 0.1%; more preferably at least about 1 % ; more preferably still, from about 1 % to about 55%.

Any optical brighteners or other brightening or whitening agents known in the art may be incorporated in the cleaning composition at levels typically from about 0.05% to about 1. 2%, by weight. Commercial optical brighteners which may be useful in the present invention can be classifie into subgroups, which include, but are not necessarily limited to, derivatives of stilbene, pyrazoline, coumarin, carboxylic acid, methinecyanines, dibenzothiphene-5,5-dioxide, azoles, 5-and 6-membered-ring heterocycles, and other miscellaneous agents.

Examples of such brighteners are disclosed in"The Production and Application of Fluorescent Brightening Agents", M. Zahradnik, Published by John Wiley & Sons, New York (1982).

Specific examples of optical brighteners which are useful in the present compositions are those identified in U. S. Patent 4,790,856, issued to Wixon on December 13,1988. These brighteners include the PHORWHlTE series of brighteners from Verona. Other brighteners disclosed in this reference include : Tinopal UNPA, Tinopal CBS and Tinopal 5BM ; available from Ciba-Geigy; Artic White CC and Artic White CWD, available from Hilton-Davis, located in Italy ; the 2- (4-stryl-phenyl)-2H-napthol [1,2-d] triazoles ; 4, 4'-bis- (1,2,3-triazol-2-yl)- stilbenes ; 4,4'-bis (stryl) bisphenyls ; and the aminocoumarins. Specific examples of these brighteners include 4-methyl-7-diethyl-amino coumarin; 1,2-bis (- venzimidazol-2-yl) ethylene ; 1,3-diphenyl-phrazolines; 2,5-bis (benzoxazol-2- yl) thiophene; 2-stryl-napth- [1, 2-d] oxazole ; and 2-(stilbene4-yl)-2H-naphtho- [1, 2- d] triazole. See also U. S. Patent 3,646,015, issued February 29,1972 to Hamilton. Anionic brighteners are preferred herein.

Depending upon its desired use, the cleaning composition may also include a plurality of adjunct ingredients known in the art, for example, any of the

adjunct ingredients described above, an alkoxylated polycarboxylate, a builder, a chelating agent, a clay soil removal/anti-redeposition agent, a dye, a dye transfer inhibiting agent, a fabric softener, a hydrotrope, a polymeric soil release agent, a polymeric dispersing agent, a processing aid, a solvent, a suds booster, and a suds suppresser.

In a preferred embodiment, the coated bleach particle of the invention is added to a solid cleaning composition, such as a tablet, or more preferably, a laundry detergent bar composition. A preferred laundry detergent bar composition comprises a detersive surfactant, a coated bleach particle, a builder, an optical brightener, and a filler. The laundry detergent bar composition may further include any of the adjunct ingredients disclosed, above, for cleaning compositions. In a more preferred embodiment, the laundry detergent bar contains as a builder, such as a phosphate builder, a silicate builder, a zeolite, or mixtures thereof. A preferred phosphate builder includes the alkali metal, ammonium and alkanolammonium salts of polyphosphates (e. g., the tripolyphosphates, pyrophosphates, orthophosphates, and glassy polymeric meta-phosphates), phosphonates, and mixtures thereof. Another preferred adjunct ingredient in a laundry detergent bar is a structurant such as a cellulose derivative, a starch, a silicate, and mixtures thereof.

Coating Process The coated bleach particle of the invention may be made by conventional coating processes wherein a core particle is coated by a coating layer. The coating layer may be applied as either a solid powder or as a liquid. A preferred process useful herein is a fluidized bed process, such as the Wurster coating process. In a fluidized bed process, the core particle is fluidized, and the coating layer is sprayed onto the core particle, as it passes by the sprayer (s). The sprayer (s) may be located on the top, bottom and/or the sides of the fluidizing equipment. Co-current, counter-current, from the side, or a combination of these spraying configurations are available. A bottom spray configuration is preferred, because it typically provides more effective spraying.

The Wurster coating process utilizes an enclose container which contains both a fluidizing mechanism and a spraying mechanism. When the particles are added to the container, they circulate in a given direction. The coating layer is applied by spraying it onto the particles as they pass by the

spraying mechanism. In the Wurster process, the particle passes through the spray in a co-current direction.

The coating layer may be dissolved in water to form an aqueous coating material solution, and then sprayed onto the core particle to form a coated bleach particle. In such a process, the coated bleach particle is typically dried simultaneous with, or immediately after coating. For example, counter-current hot air may be applied as the core particle is sprayed with the aqueous coating layer. Such a drying step reduces water-initiated degradation of the perborate bleach.

Examples of the invention are set forth hereinafter by way of illustration and are not intended to be in any way limiting of the invention.

EXAMPLE 1 Examotes of the core particle useful in the current invention include : TABLE) 123456 7 SuperPerborate 100 Perborate monohydrate-95-90-80 70 Perboratetetrahydrate--80-95-- Enzyme10 Brightener--5 Dye === 5 Filler 5 10 10 Sodiumsulfate 10---5 Binder 5-5-15 Balance* to 100% 100 100 100 100 100 100% 100% % % % % % * minors.

All percentages in Table I are by weight of the core particle.

Coating layer formulations useful in the present invention include : TABLE II A B C D E F G Water-Soluble Boron Compound borate-polyvinyl 10 20 alcohol (MW 6000, 80%hydrolyzed) 80/20 weight ratio of-20 10 borosilicate Boric Acid 100-10-90 80 Borax 50 Acid Source CitricAcid50--30 MaleicAcid30 Malic Acid 40 80 30 AdjunctIngredient Wax 10--10- C18 (stearic) acid------20 Balance* to 100% 100 100 100 100 100% 100% 100% % % % %

*minors All percentages in Table II are by weight of the coating layer.

Subject to the weight and molar ratios disclosed herein, any particle (1-7) is compatible with any coating layer (A-G). Specific examples of preferred combinations include : Particles 1 and 2 from Table I are especially preferred, when encapsulated by coating materials A and B from Table II.

EXAMPLE 2 Sodium perborate monohydrate powder having a mean particle size of 300 mm, was purchased from AtoChem, Inc. An aqueous coating layer solution of 20% boric acid, and 80% water was prepared. The sodium perborate was coated with the aqueous coating layer solution to form a coated bleach particle.

The Wurster coating process, utilizing a co-current bottom-sprayer, was used to apply a coating layer to the fluidized sodium perborate. The weight ratio of the core particle to the coating layer is about 4: 1.

The final coated bleach particle had a mean particle size of about 450 pm, while the molar ratio of water-soluble boric acid to the perborate bleach was about 1: 8.

EXAMPLE 3 Core particles (sodium perborate tetrahydrate powder) having a mean particle size of 500 mm, were purchased from Solvay Interox. A liquid coating layer containing 10% borax, and 10% citric acid, and 80% water was prepared.

The core particle was coated to form an encapsulated particle according to the process of Example 2.

The molar ratio of water-soluble boron compound to the perborate bleach was about 1: 20, while the weight ratio of the water-soluble boron compound to the acid source was about 1: 1. When stored at room temperature for 9 weeks, these coated bleach particles showed good stability, as compared to uncoated core particles.

EXAMPLE 4 The encapsulated particle of Example 3 was combined with a granular detergent composition, to form a cleaning composition. The granular cleaning composition possessed excellent cleaning and bleaching activity.

EXAMPLE 5 The following coated bleach particles were added to laundry detergent bar compositions, immediately prior to plodding and extrusion, as shown below. TABLE III A B C AdjunctIngredient* C11-13LA' Na CFAS 16 13 5 i Naalkyl sulfate (tallow) Soil dispersing/releasing polymer 1 0.5 0. 5 Optical brightener 0. 5 0.15 0. 2 Na tripolyphosphate 14 18 14 20 Nonionicsurfactant---2 Sodium carbonate 15 5 12 Moisture 3 3.4 6 3. 3 Coated Bleach Particle (details below) * 5.25 6 3. 5 5. 25 Other Adjunct Ingredients Bal. Bal TOTAL 100 100 100 100 l Details of the Coated Bleach Particle Coreparticle Superperborate** Sodium perborate monohydrate**-67-40 Sodium perborate tetrahydrate**--54- Adjunct ingredient**3 6 i CoatingLayer Boric Acid ** 20-4- Borate-polyvinyl alcohol (MW 6000,80% 4 hydrolyzed) ** 80/20 weight ratio of borosilicate** 8 5 Borax15 Citricacid** 15 15 Maleicacid**- _-16 15 Malicacid** 16 15 AdjunctIngredient**-

* by weight of the laundry detergent bar composition.

** by weight of the coated bleach particle.

These laundry bars possessed high bleaching activity both immediately after extrusion, and after aging for 9 weeks.

EXAMPLE 6 The encapsulated particle of Example 3 was combined with an acidic pH hard surface cleaning composition. The hard surface cleaning composition possessed excellent cleaning and bleaching activity.