Compositions – Oxidative bleachant – oxidant containing – or generative – Free halogen or oxy-halogen acid type
Patent
1997-11-17
1999-10-05
Anthony, Joseph D.
Compositions
Oxidative bleachant, oxidant containing, or generative
Free halogen or oxy-halogen acid type
25218726, 423473, 423140, 423 50, 423 55, 423 34, C01B 1106, C01G 100, C01G 4500, C01G 4900
Patent
active
059618795
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for the manufacture of a liquid bleaching composition which is suitable for laundry applications including handwashing as well as washing with automatic washing machines.
BACKGROUND OF THE INVENTION
Liquid bleaching compositions are well known in the art. Amongst the different bleaching compositions available, those relying on bleaching by hypochlorite are often preferred.
However, the drawbacks associated with the use of chlorine-based compositions are that said compositions may both damage and yellow fabrics.
We have now found that the whiteness performance and/or the fabric safety performance of a liquid aqueous hypochlorite-containing composition is mainly dependent on two factors: the pH of the bleaching environment and the presence of heavy metal ions in said bleaching environment.
It is believed that higher pH of the bleaching environment is beneficial for the whiteness and fabric safety performance because it shifts the chemical equilibrium between hypochlorite and hypochlorous acid to reduce the level of hypochlorous acid, the species which we have found to be the most responsible for the yellowing and the fabric damage.
The presence of heavy metal ions such as Ni, Co, Cu, Mn, Cr, and Fe adversely affects the hypochlorite bleaching performance. It is believed that in the washing environment said heavy metal ions catalyze the attack of hypochlorous acid on fabrics with the generation of yellow oxidized species. Said heavy metal ions also lead to reduced tensile strength of the fabrics, thereby reducing fabric resistance. It is further believed that said heavy metal ions are adsorbed per se on oxidized fabrics as colored species and catalyze the degradation of the brighteners adsorbed on fabrics generating thereby highly colored species on fabrics. Also, said heavy metal ions stabilize colored pigments of enzymatic stains such as blood or grass. Furthermore, it is believed that said heavy metal ions are detrimental for the performance of a hypochlorite composition as they tend to react with the hypochlorite present in said composition and thereby catalyze the decomposition of said hypochlorite.
In the current industrial manufacturing processes, liquid aqueous compositions comprising hypochlorite and a source of alkalinity, such as sodium hydroxide, are prepared by using the cheapest and most commonly available raw materials. Such commercially available raw materials are usually contaminated by impurities such as heavy metal ions. For example, the commercially available hypochlorite commonly used may contain proportions of other materials such as sodium carbonate and/or caustic soda and/or heavy metal ions. Also, the current caustic soda is commonly contaminated by heavy metal ions such as iron.
More particularly, in the current industrial manufacturing processes, such liquid aqueous compositions comprising hypochlorite are prepared by diluting a concentrated hypochlorite solution with tap water, i.e. non-demineralized water, in presence of said source of alkalinity, allowing precipitation of insoluble salts, such as metal hydroxides and metal carbonates, and finally removing said insoluble salts from said compositions. However, the compositions obtained are not satisfactory as regard their purity, because they still contain a certain level of heavy metal ions which have not been retained/eliminated by a conventional separation means like by filtering said compositions with a decantation filter. The amount of heavy metal ions in the finished composition is even higher when manufacturing a liquid aqueous composition comprising hypochlorite at high pH values such as 13 and above. Indeed, the solubility of most of the heavy metal ions that should be eliminated in order to ensure good whiteness and/or fabric safety performance, increases with the pH of the composition. Also the separation step, e.g. the filtration step, is quite a long operation, i.e. it is the most time consuming step in the overall manufacturing process of hypochlorite-cont
REFERENCES:
patent: 2438781 (1948-03-01), Kamlet
patent: 2662858 (1953-12-01), Brandon
patent: 3557010 (1971-01-01), Skrypa et al.
patent: 3755179 (1973-08-01), Fitzgerald, Jr.
patent: 3998751 (1976-12-01), Murray
patent: 4445935 (1984-05-01), Posey et al.
patent: 4561994 (1985-12-01), Rubin et al.
patent: 4780303 (1988-10-01), Dugua
patent: 4857292 (1989-08-01), Brahm et al.
patent: 4898681 (1990-02-01), Burton
patent: 5380458 (1995-01-01), Douglass
Anthony Joseph D.
Echler, Sr. Richard S.
Procter & Gamble Company
Rasser Jacobus C.
Zerby Kim W.
LandOfFree
Process for the manufacture of hypochlorite bleaching compositio does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the manufacture of hypochlorite bleaching compositio, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the manufacture of hypochlorite bleaching compositio will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1167612