Claims
- 1. A dry, granular peracid bleach and enzyme composition which as enhanced enzyme stability despite prolonged storage in the presence of said peracid bleach and improved enzyme solubility in an aqueous medium, said bleach composition comprising:
- a) an organic peracid with the structure ##STR3## wherein R is C.sub.4-20 alkyl; and b) A hydrolase which is coated substantially completely by an alkali metal silicate and an additive which is selected from the group consisting of a reducing agent, an antioxidant, a transition metal, and mixtures thereof.
- 2. The bleach composition of claim 1 further comprising one or more selected adjuncts from the group consisting of fluorescent whitening agents, bluing agents, fillers, builders, surfactants, pH adjusters, and mixtures thereof.
- 3. The bleach composition of claim 1 wherein said organic peracid of a) is a C.sub.6-12 diperacid.
- 4. The bleach composition of claim 3 wherein said organic peracid is diperoxydodecanedioic acid.
- 5. The bleach composition of claim 1 wherein said enzyme of b) is selected from the group consisting of protease, amylases, lipases, cellulases, and mixtures thereof.
- 6. The bleach composition of claim 5 wherein said coating of b) is a sodium silicate having an SiO.sub.2 :Na.sub.2 O ratio of about 1:1 to 3:1.
- 7. The bleach composition of claim 1 wherein said coating of b) further comprises an alkali metal carbonate.
- 8. The bleach composition of claim 1 wherein said additive is a reducing agent.
- 9. The bleach composition of claim 8 wherein said reducing agent is sodium sulfite or sodium perborate tetrahydrate.
- 10. The bleach composition of claim 1 wherein said additive is an antioxidant.
- 11. The bleach composition of claim 10 wherein said antioxidant is BHA or BHT.
- 12. The bleach composition of claim 1 wherein said additive is a transition metal.
- 13. The bleach composition of claim 12 wherein said transition metal is selected from the group consisting essentially of iron, cobalt, nickel, copper salts, and mixtures thereof.
- 14. A hydrolase enzyme-containing composition which has enhanced stability despite prolonged storage in the presence of peracid oxidant bleaches and improved solubility in an aqueous medium, said composition comprising:
- a) a hydrolase; and
- b) an alkali metal silicate coating therefor which substantially completely encapsulates said enzyme, said coating further including an additive which is selected from the group consisting of a reducing agent, an antioxidant, a transition metal, and mixtures thereof.
FIELD OF THE INVENTION
This is a division, of application Ser. No. 07/045,316 filed May 4, 1987, now U.S. Pat. No. 4,863,626 which is a continuation-in-part of pending U.S. patent application Ser. No. 899,461, filed Aug. 22, 1986, which is a continuation-in-part of pending applications Ser. No. 767,980, filed Aug. 21, 1985,, and Ser. No. 792,344, filed Oct. 28, 1985. The disclosure of each enumerated application is expressly incorporated herein.
This invention relates to household fabric bleaching products, and more particularly to dry bleach products which are based upon oxidant bleaches, especially organic peroxyacid bleach compositions, and which contain enzymes. The enzymes are present in the bleach composition as discrete granules which are coated to enhance the stability of the enzymes. The enzyme coating contains one or more active agents which protect the enzyme from degradation by the bleach composition.
Bleaching compositions have long been used in households for the bleaching and cleaning of fabrics. Liquid bleaches based upon hypochlorite chemical species have been used extensively, as they are inexpensive, highly effective, easy to produce, and stable. However, the advent of modern synthetic dyes and the use of modern automatic laundering machines have introduced new requirements in bleaching techniques, and have created a need for other types of bleaching compositions. In order to satisfy this need, and to broaden and extend the utility of bleaches in household use, other bleach systems have been introduced in recent years.
Of particular interest recently have been dry bleaching compositions based upon peroxyacid chemical species. Peracid chemical compositions have a high oxidation potential due to the presence of one or more of the chemical functional group: ##STR1##
In addition to active oxidizing agents, it is also desirable to provide one or more enzymes for the purpose of stain removal Enzymes have the ability to degrade and promote removal of certain soils and stains by the cleavage of high molecular weight soil residues into low molecular weight monomeric or oligomeric compositions readily soluble in cleaning media, or to convert the substrates into different products. Enzymes have the substantial benefit of substrate specificity: enzymes attack only specific bonds and usually do not chemically affect the material to be cleaned. Exemplary of such enzymes are those selected from the group of enzymes which can hydrolyze stains and which have been categorized by the International Union of Biochemistry as hydrolases. Grouped within the hydrolases are proteases, amylases, lipases, and cellulases.
Enzymes are somewhat sensitive proteins which have a tendency to denature (change their molecular structures) in harsh environments, a change which can render the enzymes ineffective. Strong oxidant bleaches such as organic peracids adversely affect enzyme stability, especially in warm, humid environments in which there is a concentration of oxidant bleaching species.
Various methods to stabilize enzymes and provide a good mixture of enzyme and detergent or bleach have been proposed. Enzymes have variously been attached to carriers of clay, starch, and aminated polysaccharides, and even coglutinated to detergent carriers. Enzymes have been granularized, extruded, encased in film, and provided with colorizing agents. Attempts have been made to enhance enzyme stability by complexing the enzymes with proteins, by decreasing the relative humidity of the storage environment, by separating the bleach into discrete granules, and by the addition of reducing agents and pH buffers. However, the instability of enzymes in peroxyacid bleach compositions has continued to pose a difficulty, especially in the long-term storage of peroxyacid bleach compositions in which enzymes and bleach are in intimate contact.
The present invention relates to enzyme-containing oxidant bleach compositions, especially organic diperacid based bleaching products. More specifically, compositions provide enzyme stability during prolonged storage in the presence of oxidants, while supporting enzyme solubility.
The improved product is prepared by coating or encapsulating the enzyme or enzymes with a material which both effectively renders the enzyme resistant to degradation in bleach products and allows for sufficient solubility upon introduction into an aqueous medium, such as found during laundering. Particularly, alkaline materials act as protective agents, which neutralize oxidant species before they contact and denature the enzyme. Exemplary of such protective agents are sodium silicate and sodium carbonate, both of which act to physically block the attack of the enzyme by oxidants, and to chemically neutralize the oxidants. Active protective agents also include reducing materials, such as sodium sulfite and sodium thiosulfite, and antioxidants such as BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole), which act to inhibit radical chain oxidation. Transition metals, especially iron, cobalt, nickel, and copper, act as catalysts to speed up the breakdown of oxidant species and thus protect the enzymes. These active enzyme protective agents may be used in conjunction with carriers, especially water-soluble polymers, which do not of themselves protect the enzyme, but which provide enhanced solubility and act as dispersant agents for protective agents.
Standard bleaching composition adjuncts such as builders, fillers, buffers, brighteners, fragrances, and the like may be included in an enzyme-containing oxidant bleach composition in addition to the discrete enzyme granules, and the oxidant bleach.
It is therefore an object of the invention to provide enzymes which are protected from denaturation in a composition containing oxidant bleaches.
It is another object of the invention to provide coated enzymes which are soluble in aqueous media.
It is another object of the invention to provide an oxidant bleach composition containing enzymes which exhibit increased stability upon storage.
It is yet another object of the invention to provide stabilized enzymes in an enzyme-containing peracid bleaching composition.
Other objects and advantages of the invention will become apparent from a review of the following description and the claims appended hereto.
US Referenced Citations (37)
Foreign Referenced Citations (8)
| Number |
Date |
Country |
| 838125 |
Jul 1976 |
BEX |
| 170360 |
Feb 1986 |
EPX |
| 200163 |
Nov 1986 |
EPX |
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Dec 1986 |
EPX |
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Non-Patent Literature Citations (3)
| Entry |
| European Search Report, EP 86306442 (published as EP 214 789) (corresponding to parent U.S. Ser. No. 06/767,980, filed 8/24/85, now abandoned). |
| European Search Report, EP 86306443 (published as Ep 212 976) (corresponding to parent U.S. Ser. No. 06/792,344, filed 10/30/85, now abandoned). |
| S. N. Lewis, "Peracid and Peroxide Oxidations," in: Oxidation (Marcel Dekker, New York, 1969), vol. 1, chapter 5, pp. 213-258. |
Divisions (1)
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Number |
Date |
Country |
| Parent |
45316 |
May 1987 |
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Continuation in Parts (2)
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Number |
Date |
Country |
| Parent |
899461 |
Aug 1986 |
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| Parent |
767980 |
Aug 1985 |
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Patent Grant
5093021
