Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-03-09
2002-01-15
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...
C510S302000
Reexamination Certificate
active
06339055
ABSTRACT:
TECHNICAL FIELD
The invention relates to bleaching compositions and cleaning compositions comprising the bleaching compositions, containing a specific photo-bleaching agent and a bleaching agent capable of providing a peroxyacid bleaching compound. The compositions are particularly useful in laundry and dish washing processes to provide enhanced photo-bleaching performance, fabric whiteness appearance and overall cleaning.
BACKGROUND OF THE INVENTION
Various compounds are known in the art which, upon exposure to light, can be photo-activated, to become an active species for chemical or further photo-chemical reactions.
Two general examples thereof are porphyrin and phthalocyanine photo-bleaching compounds. These compounds, unmetallated and especially when combined with a suitable cation, can undergo a series of reactions, starting with a photochemical reaction step which transforms the compound into an excited state. The excited state of the molecule can react with stains to bleach them or alternatively after subsequent reaction steps in conjunction with molecular oxygen can produce “active oxygen”. Active oxygen includes molecules of “singlet oxygen” or superoxide. Superoxide can subsequently be converted to hydrogen peroxide. “Singlet oxygen”, superoxide or hydrogen peroxide, formed in this series of reactions, are oxidative species capable of reacting with stains to chemically bleach them to a colourless and usually water-soluble state, thereby resulting in what is called photochemical bleaching. Examples of porphyrins or porphyrin-like compounds include haematoporphyrin, chlorophyll, chlorine, oxo-chlorins, pheophorbide, pyropheophorbide, benzoporphyrins, tetra-arylporphyrin, zinc tetraphenylporphyrin, tripyrroledimethane-derived expanded porphyrins. Examples of phthalocyanines and naphthalocyanines include zinc, aluminum, indium, silicon, and gallium phthalocyanines and naphthalocyanines, the most common being the zinc and aluminium phthalocyanines.
Other examples of photobleaches are xanthene dyes such as rose bengal, eosin, and fluorescein. Additional photobleach examples include metachromic dyes such as thionine, methylene blue, benzo[a]phenoxazinium (Nile Blue A), and benzo[a]phenothiazinium. A limitation to the use of some of these more water-soluble photo-bleaches can be their poor surface-activity.
One problem associated with the use of phthalocyanine, naphthalocyanines, and porphyrin photo-bleaching compounds arises from the fact that these are not water soluble, in particular when the parent rings are substituted solely with hydrogen.
It has been a task for the formulators of photo-bleaching compounds and cleaning products to prepare photo-bleaching agents which are soluble in water. In an effort to do so, various patent documents relate to photo-bleaching with phthalocyanine derivatives, having various solubilising substituents, such as EP-119746, EP-379312, EP-553608, EP-596187 and EP-692947. These documents teach selected substituent units that are hydrophilic and which are bonded to the photo-sensitive ring units to enhance the solubility or photochemical properties of the molecule. In general, three or more substituents are needed to obtain the required solubility.
However, a problem relating to the introduction of (high numbers of) substituent groups to the photo-bleaching compound (to ensure a certain level of water solubility) is that the photo-bleaching properties of the ring system are often affected. For example, a change which increases solubility may reduce the quantum efficiency of the molecule. This can render the derivative compound without sufficient photo-bleaching properties. Firstly, this can lead to less formation of singlet oxygen and thus less bleaching. Secondly, the absorption spectrum may change, leading to an undesirable colouring of the photo-bleaching compounds in use, which is in particular a problem when used for photo-bleaching of fabrics.
It is known in the art how to prepare these derivative photo-bleaching agents. However, the preparation of these derivative photo-bleaching agents can proceed in low yield which introduces impurities and increases cost. These impurities may also introduce undesirable colouring which produces staining, in particular when used on fabric.
Another major limitation to the use of most photo-bleaching compounds known in the art is that they are highly coloured materials (having an absorption in the range of 600-800 nanometres). For example, high concentrations of these compounds on the fabric will thus lead to staining of the fabric. Therefore, deposition of the photo-bleaching compounds in high quantities on the fabric in the wash should be avoided. Furthermore, build up of these compounds on fabric surface should be avoided.
Yet another limitation of most photo-bleaching compounds known in the art is that introduction of solubilising groups tends to destabilise the compounds so that they tend to decompose once exposed to light, in particular sunlight, which deactivates them as photo-bleaching compound, thus leading to a lesser bleaching performance. Furthermore, in cleaning compositions containing the photo-bleaching compounds it is often required that additional bleaching agents are present. However, these bleaching agents can also cause decomposition and inactivation of the photo-bleaching agents.
Thus, there is a need for improved photo-bleaching compounds which are water-soluble, which have optimum photo-bleaching properties, and will overcome the decomposition and build up problems.
The inventors now have found improved photo-bleaching agents for use in cleaning compositions. The photo-bleaching agent is formed by integrating a photo-bleaching compound (which is insoluble in water or slightly water-soluble) with a specific, water-soluble polymeric compound. The inventors have found that thus a photo-bleaching agent is obtained which is has an improved solubility in water and which has an improved surface-activity. While not being bound by theory, the improvement in photobleaching results from photo-bleaching agents which have an improved affinity for the soils present on fabric for laundering. Thus, more specific and effective bleaching of these soils is achieved. In addition, the photo-bleaching agents included in the invention may provide more efficient photo-bleaching performance because they are more stable when exposed to light or bleach. Thus for a given amount of photobleaching agent deposited on a surface, a higher amount of singlet oxygen or other bleaching species can be generated before the photobleaching agent decomposes. Also, the photo-bleaching agent has an absorption spectrum which results in a desired colour, in particular blue, of the agent and of the fabric comprising the agent. Furthermore, they have found that the photo-bleaching agent migrates evenly to the fabric surface. Thus localised high quantities of photo-bleaching agent, leading to staining, can be avoided. They also have found that the agent accumulates to a lesser extent on the fabric in subsequent washings. Also staining of the fabric by highly coloured, inactive agents can be avoided because the photo-bleaching agent of the invention can be prepared without introduction of impurities. Additionally, the photo-bleaching agent can provide a desired hueing on the fabric, leading to an improved fabric appearance.
The inventors have now found that detergents comprising these novel photo-bleaching agents and a bleaching agent capable of providing a peroxyacid bleaching species, have a surprisingly improved bleaching performance. It has been found that the efficiency of the peroxyacid-containing or peroxyacid-providing bleaching agent is improved when the novel photo-bleaching agents are present. It is believed to be caused by the generation by the photo-bleaching agent of peroxyacid radicals rather than singlet oxygen under influence of sunlight. The peroxyacid radicals are believed to provide an improved bleaching performance.
The improved performance and efficiency results in improved cleaning of
Brooker Alan Thomas
Figueroa Francisco Ramon
Heinzman Stephen Wayne
Echler Sr. Richard S.
Miller Steven W.
Petruncio John M.
The Procter & Gamble & Company
Zerby Kim W.
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