Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-02-28
2002-01-22
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S376000, C510S367000, C510S276000
Reexamination Certificate
active
06340661
ABSTRACT:
This invention relates to bleaching compositions and methods based on atmospheric oxygen, without hydrogen peroxide or a source of hydrogen peroxide, more particularly to compositions and methods for stain bleaching of laundry fabrics.
Peroxygen bleaches are well known for their ability to remove stains from substrates. Traditionally, the substrate is subjected to hydrogen peroxide, or to substances which can generate hydroperoxyl radicals, such as inorganic or organic peroxides. Generally, these systems must be activated. One method of activation is to employ wash temperatures of 60° C. or higher. However, these high temperatures often lead to inefficient cleaning, and can also cause premature damage to the substrate.
A preferred approach to generating hydroperoxyl bleach radicals is the use of inorganic peroxides coupled with organic precursor compounds. These systems are employed for many commercial laundry powders. For example, various European systems are based on tetraacetyl ethylenediamine (TAED) as the organic precursor coupled with sodium perborate or sodium percarbonate, whereas in the United States laundry bleach products are typically based on sodium nonanoyloxybenzenesulphonate (SNOBS) as the organic precursor coupled with sodium perborate.
Precursor systems are generally effective but still exhibit several disadvantages. For example, organic precursors are moderately sophisticated molecules requiring multi-step manufacturing processes resulting in high capital costs. Also, precursor systems have large formulation space requirements so that a significant proportion of a laundry powder must be devoted to the bleach components, leaving less room for other active ingredients and complicating the development of concentrated powders. Moreover, precursor systems do not bleach very efficiently in countries where consumers have wash habits entailing low dosage, short wash times, cold temperatures and low wash liquor to substrate ratios.
Alternatively, or additionally, hydrogen peroxide and peroxy systems can be activated by bleach catalysts, such as by complexes of iron and the ligand N4Py (i.e. N,N-bis(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine) disclosed in WO95/34628, or the ligand Tpen (i.e. N,N,N′,N′-tetra(pyridin-2-yl-methyl)ethylenediamine) disclosed in WO97/48787. EP-A-0909809 discloses a class of iron coordination complexes useful as catalysts for the bleach activation of peroxy compounds, including iron complexes comprising the ligand N,N-bis(pyridin-2-yl-methyl)-1,1-bis(pyridin-2-yl)-1-aminoethane, also referred to as MeN4Py. These catalysts are said to be useful in bleaching systems comprising a peroxy compound or a precursor thereof, such as in the washing and bleaching of substrates including laundry, dishwashing and hard surface cleaning, or for bleaching in the textile, paper and woodpulp industries, and in waste water treatment. According to these publications, molecular oxygen may be used as the oxidant as an alternative to peroxide generating systems. However, no role in catalysing bleaching by atmospheric oxygen in an aqueous medium is reported.
It has long been thought desirable to be able to use atmospheric oxygen (air) as the source for a bleaching species, as this would avoid the need for costly hydroperoxyl generating systems. Unfortunately, air as such is kinetically inert towards bleaching substrates and exhibits no bleaching ability. Recently some progress has been made in this area. For example, WO 97/38074 reports the use of air for oxidising stains on fabrics by bubbling air through an aqueous solution containing an aldehyde and a radical initiator. A broad range of aliphatic, aromatic and heterocyclic aldehydes is reported to be useful, particularly para-substituted aldehydes such as 4-methyl-,4-ethyl- and 4-isopropyl benzaldehyde, whereas the range of initiators disclosed includes N-hydroxysuccinimide, various peroxides and transition metal coordination complexes.
However, although this system employs molecular oxygen from the air, the aldehyde component and radical initiators such as peroxides are consumed during the bleaching process. These components must therefore be included in the composition in relatively high amounts so as not to become depleted before completion of the bleaching process in the wash cycle. Moreover, the spent components represent a waste of resources as they can no longer participate in the bleaching process.
Accordingly, it would be desirable to be able to provide a bleaching system based on atmospheric oxygen or air that does not rely primarily on hydrogen peroxide or a hydroperoxyl generating system, and that does not require the presence of organic components such as aldehydes that are consumed in the process. Moreover, it would be desirable to provide such a bleaching system that is effective in aqueous medium.
In order to prevent transfer of dyes from one fabric substrate to another fabric substrate during cleaning processes, such as in laundry detergent bleach washes, it is known and often desired to include dye transfer inhibition agents in bleaching compositions based on hydrogen peroxide, peroxide compounds and/or peroxyacids. The use of various polymers as dye transfer inhibitors (DTIs) in laundry detergent compositions and rinse conditioners has been described in the prior art. For example WO-A-0005334 discloses laundry detergents providing dye transfer inhibition benefits. Examples of well-known polymers include polyvinyl pyrrolidone (PVP), and copolymers of N-vinylpyrrolidone and N-vinylimidazole (PVPVI).
However, due to the strong catalytic bleaching activity of certain bleach catalysts in the absence of hydrogen peroxide, peroxide compounds and/or peroxyacids, it might be expected that these catalytic bleaching systems would oxidise or otherwise interfere with the action of polymeric dye transfer inhibition agents. At the same time, the presence of dye transfer inhibition agents in these bleach systems might be expected to reduce the catalytic bleaching activity of the bleach catalysts with atmospheric oxygen. It was therefore expected that the combination of a bleach catalyst and dye transfer inhibition agent in an atmospheric oxygen bleaching composition would result in a reduction in the catalytic activity of the catalyst or in the activity of the dye transfer inhibition agent, or both.
We have now found, surprisingly, that it is possible to provide a bleaching composition and method for stain bleaching of laundry fabrics, which can both yield comparable or improved stain bleaching performance as well as comparable or improved dye transfer inhibition on fabrics, relative to conventional bleaching systems. More particularly, we have found that excellent bleaching performance together with good dye transfer inhibition can be provided by atmospheric oxygen bleaching compositions and methods (i.e. in the absence of hydrogen peroxide or a source of hydrogen peroxide), by using a bleach catalyst as defined herein in combination with a dye transfer inhibition agent, as specified herein.
Accordingly, in a first aspect, the present invention provides a bleaching composition for laundry fabrics comprising:
a bleach catalyst comprising a ligand which forms a complex with a transition metal, the complex catalysing bleaching of stains in the absence of peroxygen bleach or a peroxy-based or -generating bleach system; and
a dye transfer inhibition agent,
and wherein the composition is substantially devoid of peroxygen bleach or a peroxy-based or -generating bleach system.
In a second aspect, the present invention provides a method of bleaching stains on laundry fabrics comprising contacting the stained fabric with the above bleaching composition.
We have found that the use of certain bleach catalysts, the most preferred of which is FeMeN4Py, in the absence of a source of hydrogen peroxide, provides good bleaching performance on fabric stains, despite the presence of the dye transfer inhibition agent. Furthermore, we have found that the presence of the bleach catalysts does not adversely affe
Hage Ronald
van Deurzen Maria Petra
Veerman Simon Marinus
Gupta Yogendra N.
Honig Milton L.
Petruncio John M
Unilever Home & Personal Care USA , division of Conopco, Inc.
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