Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-12-20
2003-05-13
Delcotto, Gregory (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S303000, C510S304000, C510S309000, C510S372000, C510S375000, C510S499000, C510S466000, C510S506000
Reexamination Certificate
active
06562774
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of bleaching compositions to remove stains from articles, in particular textile articles. In addition the present invention relates to a method of preparing a bleaching composition and method to bleach articles.
BACKGROUND OF THE INVENTION
It is known in the art to use hydrogen peroxide or organic peracids or their precursors to remove stains from metal, ceramic, plastic or textile articles.
More recently, cleaning with carbon dioxide has been described. Dense phase carbon dioxide has been suggested as an alternative to perchloroethylene for health and environmental reasons. For example, a dry cleaning system in which chilled liquid carbon dioxide is used to extract soils from fabrics is described in U.S. Pat. No. 4,012,194.
However, it has been recognised that additives are needed to boost the cleaning by this medium. For example, the use of ethoxylated tertiary acetylenic alcohol and diol surfactants for boosting the cleaning performance from condensed phase carbon dioxide are taught in U.S. Pat. No. 5,789,505. U.S. Pat. No. 5,431,843 discloses a perhydrolysis system for use in condensed fluid medium for bleaching of stained garments. This perhydrolysis system comprises two essential components: hydrogen peroxide and an organic peracid precursor. The examples seem to indicate that a combination of hydrogen peroxide and nonanoyloxyglycoylphenyl sulfonate (NOGPS) results in a better overall stain removal when compared to hydrogen peroxide alone. To obtain these results, the bleaching process takes place for at least 1 hour. U.S. Pat. No. 5,676,705 describes the use of organic peracid precursor in a dry cleaning process using carbon dioxide. Herein, both the preformed peracids and the directly added organic peracid precursor should be soluble in densified carbon dioxide.
The use of low-active oxygen bleaching agents for removal of soil from garments in aqueous systems is known. U.S. Pat. No. 3,332,882 describes the use of such bleaching agents in combination with triazine activators. U.S. Pat. No. 4,300,897 discloses a method of bleaching using peroxomonosulfate-based compositions. WO-A-9923197 describes a process of soaking fabrics with a liquid aqueous persulfate salt-containing composition. And, WO-A-9921950 discloses the use of peroxonitrite based bleaching systems. However neither of these documents discloses or suggests to the skilled person that low-active oxygen bleaching agent could be effective in a bleaching method wherein the medium is mainly carbon dioxide. U.S. Pat. No. 5,431,843 only exemplifies the use of liquid hydrogen peroxide in combination with an organic peracid precursor. For bleaching in carbon dioxide persulfate is mentioned as possible sources of peroxygen but only in combination with an organic peracid precursor. There is no disclosure or suggestion for the skilled person that an low-active oxygen bleaching agent alone would have an effective bleaching effect.
Although organic peracids and/or precursor systems are generally effective they still exhibit several disadvantages. For example, these precursor systems have large formulation space requirements as they also need addition of hydrogen peroxide and/or a hydrogen peroxide delivery system. Consequently, a significant proportion of the cleaning formulation must be devoted to the bleach components, leaving less room for other active ingredients and complicating the development of concentrated formulations. Furthermore, the efficacy of bleaching systems that are based on hydrogen peroxide tend to be adversely affected by catalase present in soiled articles. Moreover, organic precursor systems do not bleach very efficiently in situations wherein short bleach times are desired and processing environment is acidic or pH neutral.
Accordingly, it is an object of the invention to provide an alternative bleaching composition and method of bleaching which shows effective stain removal but does not display one or more of these drawbacks. One particular object of the invention is to provide a bleaching composition and method of bleaching which are economical and require short bleach times. Another object of the invention is to provide a bleaching composition and a method of bleaching which are particularly suitable for removing grass, tea and blackcurrant stains.
Surprisingly, we have now found that one or more of these objects can be achieved by the inventive bleaching composition and method of bleaching which are substantially free of carbon dioxide-soluble organic peracid and still show a remarkably effective stain removal.
DEFINITION OF THE INVENTION
Accordingly, in a first aspect of the invention a bleaching composition is provided comprising
a) a bleach-effective amount of a low-active oxygen bleaching agent;
b) a bleach-compatible solvent
c) 0 to 10 wt % of a surfactant;
d) less than 10 wt % of a modifier; and
e) an effective dry cleaning amount of densified carbon dioxide, said composition being essentially free of carbon dioxide soluble organic peracid.
In a second aspect of the invention a method to prepare the inventive composition is provided, characterised in that said method comprises the steps of
a) mixing the low-active oxygen bleaching agent in a bleach-compatible solvent; and
b) mixing the solvent and low-active oxygen bleaching agent of step a) with the carbon dioxide.
In a third aspect of the invention a method is provided, comprising the following steps:
a) mixing a bleach-effective amount of a low-active oxygen bleaching agent in a bleach-compatible solvent, preferably an aqueous solvent; and
b) contacting said article with a bleaching composition according the invention, said composition comprising the resulting mixture of step a).
Preferably, the inventive composition and method is suitable to bleach articles in less than 45 min.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is particularly advantageous for bleaching methods that require a short period of time. U.S. Pat. No. 5,431,843 describes bleaching times of 1 hour for effective stain removal. Unexpectedly we have now found that the present invention provides effective bleaching in 45 minutes or less. Another advantage of the present invention is the simplicity. Organic peracid precursors as described in the prior art often need a high pH to drive the perhydrolysis process. Since carbon dioxide has a low pH, special measures have to be taken to ensure the formation of relatively unstable peracids in a separate premix process. Furthermore, the low temperatures used in carbon dioxide cleaning will also slow this reaction. Yet another advantage of the present invention is the resistance to catalase present in soiled articles because the inventive composition and bleaching method are not based on hydrogen peroxide.
It is believed that the low-active oxygen bleaching agents are able to rapidly and effectively remove stains because these low-active oxygen bleaching agents do not need to be formed from an organic peroxyacid precursor and hydrogen peroxide. Instead, the low-active oxygen bleaching agents are added in their bleach reactive form. Consequently, another advantage of the present invention is that it is remarkably effective on a variety of stains, especially grass, tea and black currant stains. Without wishing to be bound by theory it is believed that because the inventive bleaching agents are insoluble in carbon dioxide, only minute amounts will be present in the carbon dioxide phase resulting in less dye damage.
The present invention is especially suitable to bleach and clean garments but may also be employed to bleach articles with hard surfaces.
For purposes of the invention, the following definitions are used:
“The bleaching composition” describes the total of the liquid carbon dioxide, the low-active oxygen bleaching agent, the modifier if present and optionally other additives.
“Carbon dioxide-soluble organic peracids” are those organic peracids that are soluble in carbon dioxide to greater than 0.001 wt % at pressures of about 101 kPa to 68.9
Bijl Dirk Johannes
Hage Ronald
Kevelam Jan
Koek Jean Hypolites
Murphy Dennis Stephen
Delcotto Gregory
Honig Milton L.
Unilever Home & Personal Case USA, division of Conopco, Inc.
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