Bleaching compositions

Details Bleaching compositions Bleaching compositions

2000-08-22

2001-12-04

Del Cotto, 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...

C510S220000, C510S224000, C510S311000, C510S312000, C510S372000, C510S376000, C510S378000, C252S186380, C252S186330

Reexamination Certificate

active

06326342

ABSTRACT:

This invention relates to bleach catalysts for use in bleaching compositions which may be used in detergent or cleaning compositions.
Detergents designed for fabric cleaning applications frequently contain bleaching agents. The purpose of these is primarily to oxidise chemically, and consequently remove, certain types of (“bleachable”) stains but also to kill bacteria, which can otherwise lead to the spread of disease and be detrimental to human health.
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 (40-60° C.), they are most commonly employed with so-called bleach activator compounds. The bleach activator, an example of which is the compound 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, there is considerable interest in reducing concentrations and reducing quantities of detergents by reducing the levels of high volume ingredients such as bleach, with a view to providing compositions containing less chemicals and at lower cost. Further, as washing temperatures continue to decline, as a result of the demand for greater energy efficiency, even the commercially used activated bleaching 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.
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 bleaching system in the wash liquor are needed to give equivalent performance since the bleach is effectively targeted to the stains. Sodium nonanoyloxybenzene sulphonate (NOBS) 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, and some improvement of detergent performance at temperatures below 40° C., further improvement is required.
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) reduction in the cost of the overall bleach package, (IV) ease of processability into detergent formulations, (V) storage stability and compatibility with other detergent ingredients, (VI) non-toxic nature, and (VII), in the case of bleach activators for laundry use, lack of dye and fabric damage.
Another approach considered has been the use of pre-formed peracids as bleaches. Examples of these are diperoxydodecanedioic acid (DPDDA) and phthaloylaminoperoxycarboxylic acids. Although these, and other examples of pre-formed peracids, can lead to better bleaching performance than 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 and further is not currently attractive from a cost point of view.
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 WO96/23859, WO96/23860, WO96/23861, WO97/00311 and WO97/00312 disclose cobalt catalysts such as [Co(NH
3
)
5
OAc]Cl
2
to provide enhanced cleaning/bleaching benefits in automatic dishwashing detergents. These documents teach that, in general, the evidence points to cobalt catalysts making in particular poorer fabric bleach catalysts than manganese complexes. EP-A-458,397 and EP-A-458,398 describe other manganese-based bleach catalysts for enhancement to persalt bleaching of stains on fabrics during washing at temperatures below 40° C. EP-A-384,503 describes modifications made to metalloporphyrin catalysts, intended for use as bleach catalysts, which are intended to make them more stable against oxidation by oxidant (e.g. peroxyacid).
Polyoxometalates are salts or acids having inorganic cluster-like oxo-anions and may be formed from simple vanadium, niobium, tantalum, molybdenum or tungsten compounds under appropriate conditions in aqueous or organic media (see C. L. Hill & C. M. Prosser-McCarthy, Coordination Chemistry Reviews 143 (1995) 407-455, I. V. Kozhevnikov, Catal. Rev. Sci. Eng., 37(2) 311-352 (1995)).
EP-A-549,077 describes particular tungsten containing polyoxometalates which are considered to be good oxidising agents. Furthermore their use as additives in the detergency field is proposed.
WO97/07886 describes the use of manganese-containing polyoxometalates of specified formula as oxidation catalysts in detergent and cleaning agents.
Additionally EP-A-761,809 describes the use of polyoxometalates as bleach catalysts in bleaching agent compositions. In particular the polyoxometalates used are stated to be preferably of the general formula:
(Q)
q
(A
a
X
x
M
m
O
y
Z
z
(H
2
O)
b
).cH
2
O  (I)
where the symbols Q, A, X, M, Z, q, a, x, m, z, b and c have the following meanings:
Q stands for one or more cations selected from the group comprising H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PR
1
R
2
R
3
R
4
and NR
1
R
2
R
3
R
4
in which R
1
, R
2
, R
3
and R
4
are the same or different and represent H, C
1
-C
20
-alkyl, C
5
-C
8
-cycloalkyl or C
6
-C
24
aryl;
q stands for a number from 1 to 60, and describes the charge of the anionic unit in monovalent counter-cations;
A stands for one or more transition metals from the 2
nd
to 8
th
subsidiary group;
a stands for a number from 0 to 10,
X stands for one or more atoms selected from the group comprising Sb, S, Se, Te, Bi, Ga, B, P, Si, Ge, F, Cl, Br and I;
x stands for a number from 0 to 10;
M stands for one or more transition metals selected from the group comprising Mo, W, Nb, Ta and V;
m stands for a number from 0.5 to 60;
Z stands for one or more anions selected from the group comprising OH
−
, F
−
, Cl
−
, Br
−
, I
−
, N
3
−
, NO
3
−
, ClO
4
−
, NCS
−
, SCN
−
, PF
6
−
, RSO
3
−
, RSO
4
−
, CF
3
SO
3
−
, BR
4
−
, BF
4
−
, CH
3
COO
−
where R equals H, C
1
-C
20
-alkyl, C
5
-C
8
-cycloalkyl or C
6
-C
24
aryl;
z stands for a number from 0 to 10;
y stands for the number of oxygen atoms needed to compensate the structure/charge and
b and c stand independently of one another for numbers from 0 to 50.
The preferred polyoxometalates according to EP-A-761,809 are
Q
8
[MnMo
6
O
24
] (Q=Na or NMe
4
or a mixture of the two)
K
4
[MnMo
6
O
8
(OH)
6
]
(NH
4
)
10
[Mn
3
Sb
2
W
19
O
68
]*
Na
17
[Mn
2
Se
6
W
24
O
94
Cl]*
Na
2
(NMe
4
)
2
[Mn
2
W
12
O
40
(OH)
2
].12H
2
O
(Na/K)
10
[Mn
3
Se
2
W
18
O
66
]*
Na
8
[MnW

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