Dry bleach compositions

Details Dry bleach compositions Dry bleach compositions

2002-08-26

2004-08-10

Anthony, Joseph D. (Department: 1714)

Compositions

Oxidative bleachant, oxidant containing, or generative

Contains inorganic peroxide

C423S281000, C423S279000, C510S368000, C510S197000, C510S240000, C510S309000, C510S378000

Reexamination Certificate

active

06773625

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to dry bleach compositions, especially useful for cleaning hard surfaces or fabrics.
BACKGROUND OF THE INVENTION
Dry bleach compositions for household use generally differ from typical laundry or hard surface cleaners in that they contain an increased level of bleach, and are typically used for stain removal from surfaces such as hard surfaces (e.g., in the kitchen or bathroom) or fabrics (e.g., laundry). The dry bleach compositions may employ a peroxy bleach. Particularly suitable, due to lower cost, is sodium perborate because it is stable within the composition. By contrast, percarbonate typically requires coating and, thus, can be more expensive and less stable.
U.S. Pat. No. 4,650,599 (Farnworth et al.) discloses free flowing laundry powder compositions containing 4-50% surfactant, 5-50% perborate and 5-80% carbonate. Chinese patent CN 1064885 discloses brushing powder and dry cleaning paste which may contain 2-30% surfactant, 0-4% perborate and either sodium carbonate or sodium sulfate in a range of 0-15%. Example 9 is a dry cleaning powder containing, among other ingredients, 90% starch and talc, 4.5% surfactant, 2% carbonate, 3% anhydrous sulfate and 0.4% perborate. WO 92/21744 discloses dry bleach composition, to be used as an additive in the laundry, with improved dispersability containing 5-50% perborate, 25-80% carbonate, optionally sulfate in an amount of 0-80%, preferably 10-50%, and optionally up to 5% surfactant.
Typically, the compositions are used as adjuncts in cleaning or laundry. A commercial bleaching multi-purpose stain remover product is “all” Oxi-active®, containing a mixture of perborate and carbonate. The consumers are directed to mix the “all” Oxi-active® powder with some water and then apply the resulting solution or paste to a stain or a surface area in need of cleaning. Consumers do not necessarily wash off the applied paste right away, perhaps believing that cleaning/stain removal will be more effective if the paste is left on the surface for some time. It has been found, as part of the present invention, that, unfortunately, compositions which contain high levels of perborate and carbonate, cake-up and harden upon standing, forming a hard crust that is difficult to remove by mechanical means and/or which might not be readily dispersible in the laundry machine, particularly when cold water is employed.
SUMMARY OF THE INVENTION
The present invention includes a dry bleach composition comprising:
(a) from about 10% to about 80%, by weight of the composition, of sodium perborate;
(b) from about 10% to about 50%, by weight of the composition, of an anhydrous carbonate salt;
(c) from about 3% to about 40%, by weight of the composition, of an anhydrous sodium sulfate;
(d) from about 0% to about 3%, by weight of the composition, of a detergent surfactant.
Another aspect of the present invention is the paste which results from combining the inventive dry bleach composition with water.
Yet another aspect of the present invention are methods of cleaning surfaces with the inventive dry bleaching compositions.
Surprisingly, the inclusion of sulfate in certain ratios to carbonate prevents the hardening of the perborate/carbonate product when diluted with water.
DETAILED DESCRIPTION OF THE INVENTION
Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about.” All amounts are by weight of the final composition, unless otherwise specified.
It should be noted that in specifying any range of concentration, any particular upper concentration can be associated with any particular lower concentration.
For the avoidance of doubt the word “comprising” is intended to mean “including” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive.
“Dry” means that that the composition is powdered or granular, dry-blended, as opposed to liquid.
“Anhydrous” means that water of hydration is always less than 0.5 molecule of water per molecule of salt.
“Paste” means a mixture that results from combining the inventive compositions with from about 20% to about 80% water; it may be runny or somewhat hard.
Perborate
Sodium perborate suitable for use in the present invention may be in the form of tetrahydrate or monohydrate. Monohydrate is preferred, due to better stability and cost effectiveness. Sodium perborate is employed in an amount of from 10 to 80%, preferably, in order to attain improved cleaning/stain removal from 30 to 60%, most preferably from 35 to 45%, optimally to attain maximum cleaning at minimum cost, at about 50%.
Carbonate Salt
Suitable carbonate salt is preferably selected from alkali-metal carbonates, sesquicarbonates and bicarbonates. Preferred are sodium and/or potassium carbonates, most preferably sodium carbonate due to better cost effectiveness. The carbonate salt acts as the builder to remove divalent metal ions such as calcium, and additionally provides alkalinity and aids in soil removal.
Both the carbonate and the sulfate included in the present invention are anhydrous, in order to minimize excessive caking and improve the ease of dissolution in the laundry and/or removal from hard surfaces. Thus the sulfate and the carbonate, each contain less than 0.5 molecule of water per molecule of salt.
The carbonate salt is employed in an amount of from 10 to 50%, preferably, in order to attain improved cleaning/stain removal from 12.5 to 45%, most preferably from 15 to 45%.
Sulfate
Sodium sulfate is included in the inventive compositions in an amount of from 3 to 40%, in order to obtain a composition which does not harden extensively when mixed with water and let stand, and yet is not excessively crumbly or crystalline. Preferably, the sulfate is included in an amount of at least 5%, most preferably from 5 to 37.5%.
The preferred inventive compositions, in order to attain optimum cleaning and optimum paste properties include the carbonate and the sulfate in a ratio from 1:5 to 10:1, most preferably from 1:3 to 7:1.
The inventive compositions are bleach compositions, thius they are preferebly formulated to not include substantial amounts of ingredients other than perborate, the carbonate salt and the sulfate. Preferably, the total amount of perborate, alkaline builder, and sulfate in the inventive compositions is at least 90%, preferably at least 95%, and most preferably at least 98%.
Optional Detergent Surfactant
The inventive compositions preferably do not include a detergent surfactant, particularly when they are intended for hard surface cleaning include less than 3%, preferably less than 2%, most preferably less than 1%.
When included, surface active agents may be selected from the group consisting of anionic, nonionic, cationic, amphoteric and zwitterionic surfactants or mixtures thereof.
Anionic surface active agents which may be used in the present invention are those surface active compounds which contain a long chain hydrocarbon hydrophobic group in their molecular structure and a hydrophilic group, i.e. water solubilizing group such as carboxylate, sulfonate or sulfate group or their corresponding acid form. The anionic surface active agents include the alkali metal (e.g. sodium and potassium) water soluble higher alkyl aryl sulfonates, alkyl sulfonates, alkyl sulfates and the alkyl poly ether sulfates. They may also include fatty acid or fatty acid soaps. One of the preferred groups of anionic surface active agents are the alkali metal, ammonium or alkanolamine salts of higher alkyl aryl sulfonates and alkali metal, ammonium or alkanolamine salts of higher alkyl sulfates. Preferred higher alkyl sulfates are those in which the alkyl groups contain 8 to 26 carbon atoms, preferably 12 to 22 carbon atoms and more preferably 14 to 18 carbon atoms. The alkyl group in the alkyl aryl sulfonate preferably contains 8 to 16 carbon atom

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