Bleaches active components

A variety of liquid bleach additives are now being offered in dual-chamber bottles to separate the bleach active component from alkalinity or sensitive enzymes. Several patents also describe the use of the peracid PAP in such formulations, but to date no such product is commercially available. 

Sharma, S. and York, D. W., inventor, WO 97/27280 Process for making particulate bleach activator component, Procter Gamble, 1997. 

Hypochlorous acid, HOCI, is one of the active components in household bleach. 

The basic factor to be borne in mind when bleaching with hypochlorites is that the active component can exist in three different states. 

Sodium hypochlorite is the active component in household bleach, a 1 lO dilution of which is recommended by the Centers for Disease Control and Prevention for the disinfection of blood spills that may contain HIV or hepatitis B virus (HBV). 

Reactive oxygen species (ROS) is a term that describes (i) free radicals, e.g. the hydroxyl radical OH (NB it differs from the hydroxyl ion OH ) (ii) ions, e.g. the hypochlorite ion C10 , the conjugate base formed from the dissociation of hypochlorous acid and the active component of domestic bleach (iii) a combined free radical and ion, e.g. the superoxide anion 02 or (iv) molecules, e.g. hydrogen peroxide H2O2. 

This chapter will cover low-temperature bleach activators, catalysts utilizing peroxide or atmospheric oxygen for the oxidation reaction, and oxygen transfer agents that act as performance boosters for common bleach systems. Optimum conditions of use to maximize performance and avoid negative secondary reactions are described. Special attention is given to the various finishing processes, application forms, and delivery concepts that enable sensitive bleach components to be incorporated in household products, improve stain removal performance, and deliver an attractive appearance for consumers. 

Difficulties may arise with respect to the compatibility of the additive with the active component as well as with other detergent formulation ingredients. For example, the storage stability of the bleach active can be improved by choosing additives that are less prone to... 

The use of bleach in liquid systems and the related difficulties will be described in more detail in Section 16.4.3. If the incorporation of solid bleach active ingredients is considered, storage stability, prevention of uncontrolled particle sedimentation, and liquid rheology all need to be addressed. Various approaches are described to achieve sufficient storage stability of the bleach components. These mainly involve particle coating and encapsulation (see example for SPC with a doublecoating in Ref 150). To provide stable suspensions containing solid bleach components, a defined particle size of the active and a specific formulation are important. For example, the bleach active has to be milled to a defined maximum particle size prior to incorporation in the Uqnid formulation. Additives to prevent particle sedimentation may include polymers or thickeners (see example for TAED in Ref. 151). Alternatively, the use of solvents instead of aqueous systans is also reported (see example for PAP in Ref 152). 

Once the appropriate treatment process has been selected to transform the bleach active into a suitable physical form, a manufacturing process has to be developed. Alternatively, sourcing from a supplier can be considered. In both cases, the product properties of sample material must be examined, and the fit to the defined requirements needs to be assessed. To characterize the product and powder properties of the finished (soUd) bleach components, a wide variety of test methods is... 

Although over the past 30 years a large number of quite different bleach systems have been described in the literature, and some have been extensively test-marketed, only a few products have gained commercial attention. With an estimated annual consumption of 75 kt, TAED is the most widely used bleach activator for laundry applications. In combination with perborate or percarbonate, it is the major component of nearly all European HDPDs. Within the past decade, new markets for TAED have opened up in Eastern Europe, North Africa, the Middle East, and parts of South America. 

Other species In order to maintain bleach actives in the wash bath, it is essential that the other components of the formulation do not react with the peroxygen species. The majority of detergent components are compatible. 

The instability of DAST-type brighteners towards chlorine-containing bleaches has been mentioned already. They also show limited stability towards per-acids. As recommended washing temperatures have tended to fall in recent years, a bleach consisting of sodium perborate activated by addition of tetra-acetylethylenediamine (11.63) has become an important component of household detergent formulations. This system is effective at temperatures as low as 40-50 °C. Since the FBA may be sensitive to the activated oxidant, however, in some formulations it is necessary to protect compounds such as 11.60 or 11.61 by encapsulating either the brightener or the activator, if adequate shelf-life is to be maintained. 

BPN is a 275 amino acid protease with a serine in the active site. Since it is functional in an alkaline environment it has potential use in detergent applications. Our program was to change specific characteristics of BPN to make it more effective in certain applications. Two main activities were targeted pH range and oxidative stability (since bleaches are often components of detergents). 

As discussed, addition of enzyme active soya flour changes the composition of volatile compounds of white bread. In its practical application as a bread improver component, the soya lipoxygenase isoenzymes are sufficient stable for 5 months to meet the bleaching requirements. 

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