Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
2000-07-07
2002-03-19
Hardee, John (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
active
06358905
ABSTRACT:
This invention relates to bleach catalysts for use in cleaning or detergent compositions.
European laundry detergents usually contain oxygen-based bleaching agents such as sodium perborate or sodium percarbonate. These bleaches work well at temperatures above 60° C., but to boost their overall effectiveness at today's relatively low washing temperatures (e.g. 40-60° C.), they are most commonly employed with so-called bleach activator compounds. The bleach activator, an example in commercial use of which is tetraacetylethylenediamine (TAED), is typically employed at a level of 3-6% in the detergent and reacts stoichiometrically with the persalt to yield a stronger oxidising agent, e.g. peracetic acid. This oxidant is better able to bleach stains than hydrogen peroxide and also has superior biocidal activity. However, as washing temperatures continue to decline, as a result of the demand for greater energy efficiency, even the commercially used activated bleach systems are becoming less attractive since their performance is known to decrease rapidly below 40° C. Another drawback of these types of activator is their significant cost contribution to the detergent formulation, especially in proportion to that of the persalt component. Their rate of dissolution at low temperatures is also likely to reduce their effectiveness and may cause localised dye damage.
The development of interfacially active bleach activators, which react with persalts to produce peracids which are in turn interfacially active, has improved the performance of oxygen bleaches under certain conditions. The technology has meant that lower concentrations of the bleach system in the wash liquor are needed to give equivalent performance since the bleach is effectively targeted to the stains. Sodium nonanoyloxybenzene sulphonate (SNOBS) as described in U.S. Pat. No. 4,412,934, is an example of this type of activator. Although this disclosure has resulted in the successful introduction of perborate bleach-based detergents into the United States, where lower detergent concentrations are typically employed, it has done little to improve detergent performance at temperatures below 40° C.
Much effort is being expended in the search for new organic bleach activators, however at present none has emerged which fulfils all the requirements, which must include (I) significantly improved bleach activity below 40° C., (II) fast dissolving rate, (III) low cost, (IV) ease of processability into detergent formulations, (V) storage stability, (VI) compatibility with other detergent ingredients, and (VII) a non-toxic nature.
Another approach considered has been the use of pre-formed peracids as bleaches. An example of this is diperoxydodecanedioic acid (DPDDA). Although this, and other examples of pre-formed peracids, can lead to better bleaching performance than tetracetylethylenediamine (TAED) activated perborate, the peracids generally need stabilising coatings (as described for example in U.S. Pat. No. 4,100,095). Their use can also cause pin-hole damage to dyed fabrics.
Yet another approach taken within the detergents industry has been the use of bleach catalysts which work with oxygen bleaches such as sodium perborate or sodium percarbonate. EP-A-237,111 and EP-A-443,651 describe bleaching compositions comprising a water soluble complex of manganese with a multidentate ligand, such as hydroxycarboxylic acid and non-carboxylate polyhydroxy compounds respectively. EP-A-272,030 and EP-A-392,592 disclose Co(III)amine complexes (e.g. [Co(NH
3
)
5
Cl]Cl
2
) and Co(bispyridylamine)Cl
2
complexes respectively, as effective catalysts for activating hydrogen peroxide compounds in removing stains from substrates, such as fabrics. Other patent specifications, for example WO 96/23859, WO 96/23860 and WO 96/23861, disclose cobalt catalysts such as [Co(NH
3
)
5
Cl]Cl
2
and Co-SALEN type complexes to provide enhanced cleaning/bleaching benefits in automatic dishwashing detergents. Catalysts described by Rage et.al. in Nature 369, 637-639 (1994) and also in EP-A-458,397 and EP-A-458,398 are examples which give a considerable enhancement to persalt bleaching of stains on fabrics during washing at temperatures below 40° C. However, these catalysts are prone to causing unacceptable dye and fabric damage due to the formation of radical catalyst decomposition products.
Another important characteristic of bleach catalysts is their hydrolytic stability. Lack of hydrolytic stability of the catalysts can result in precipitation out, under alkaline wash conditions, of insoluble transition metal oxides or hydroxides resulting in most undesirable brown staining. It is thus important that the complex employed as catalyst must have good hydrolytic activity on the one hand but still have good effectiveness as bleach catalysts on the other hand.
It has now surprisingly been found that water-soluble complexes of cobalt with aminated and/or alkylated mono- or oligo-saccharides, optionally in reduced or oxidised form, and salts thereof have high effectiveness as bleach catalysts and have high hydrolytic stability.
According to one aspect of the present invention, there is provided a water-soluble complex of (a) one or more cobalt ions and, as ligand, (b) one or more aminated and/or alkylated mono- or oligo-saccharides, optionally in reduced or oxidised form, and salts thereof for use as a bleach catalyst, in particular for a cleaning or detergent composition.
Suitably, in the complex used according to the present invention the cobalt ion(s) (a) is/are complexed with (b) one or more compounds of the general formula I
wherein
R
1
is selected from CH
2
OH, CO
2
H, CO
2
⊖
M
⊕
(wherein M is an alkali metal or ammonium ion) and groups of the formula (a) to (d)
and n is an integer from 1 to 3;
one of R
2
and R
3
is H and the other is selected from H, OH and groups of the formula (e) to (h)
and m is an integer from 1 to 3;
one of R
4
and R
5
is H and the other is OH;
one of R
6
and R
7
is H and the other is OH or NH
2
; and
one of R
8
and R
9
is H and the other is OH, OCH
2
(CH
2
)
p
CH
3
(wherein p is an integer from 6 to 16), or a group of the formula
provided that one of R
6
and R
7
is NH
2
and/or one of R
8
and R
9
is OCH
2
(CH
2
)
p
CH
3
.
Also in the complex used according to the present invention, the cobalt ion(s) (a) may be complexed with (b) one or more compounds of the general formula II
wherein
each of R
10
and R
11
, which may be the same or different, represents H, CH
2
OH, CO
2
H or CO
2
⊖
M
⊕
(wherein M is as defined above); and
each of l and k is an integer of 2 to 5 and k is equal to or less than l.
Preferably the cobalt ion(s) (a) is/are complexed with (b) D-mannosamine, D-glucosamine, or D-galactosamine, or with (b) one or more alkyl polyglucosides having a degree of polymerisation up to 5 and wherein the alkyl groups contain 8 to 18 carbon atoms.
Suitably the complex used according to the invention is a Co(II) or a Co(III) complex.
The complexes used according to the invention may be prepared by a method which comprises contacting in aqueous solution (A) a water-soluble compound capable of releasing Co(II) or Co(III) ions on addition to water with (B) one or more aminated and/or alkylated mono- or oligo-saccharides, optionally in reduced or oxidised form, and salts thereof.
For example, cobalt chloride hexahydrate (0.53 g) and mannosamine hydrochloride (24.1 g) were dissolved in 500 ml of demineralised water, the pH of the solution was adjusted to 10 using 1M sodium hydroxide solution and the solution was evaporated to dryness in a rotary evaporator.
The molar ratio of the ligand to cobalt may generally be between 1:1 and 500:1 with ratios in the region 50:1, e.g. 20:1 to 80:1 being particularly suitable.
According to another aspect of the present invention there is provided a cleaning or detergent composition comprising:
(I) a bleaching agent, and
(II) as bleach catalyst, a water-soluble complex as defined according to the present invention.
The cobalt
Bunton Clifford A.
Greenhill-Hooper Michael J.
Render Carmel M.
Ganderup Kurt R.
Hardee John
U.S. Borax Inc.
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