Manganese bleach activators

A catalyst for the controlled decomposition of peroxy compounds is provided which comprises a water-soluble manganese (II) salt adsorbed onto a solid inorganic silicon support material, the combination having been prepared at a pH from 7.0 to 11.1.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a bleach activator, processes for its preparation 
and dry bleaching powders incorporating this activator. 
2. The Prior Art 
Dry bleaching powders for cleaning laundry generally contain inorganic 
persalts as the active component. These persalts serve as a source of 
hydrogen peroxide. In the absence of an activator, persalt bleach activity 
is undetectable where temperatures are less than 100.degree. F. and 
delivery dosages less than 100 ppm active oxygen. Activators have been 
recognized in the art as a method for effectuating bleaching under mild 
conditions. 
U.S. Pat. No. 3,156,654 discloses heavy metal ions such as cobalt in 
combination with a chelating agent to catalyze peroxide decomposition. 
U.S. Pat. No. 3,532,634 suggests as effective persalt activators 
transition metals having atomic number 24 to 29 alongside a chelating 
agent. Neither process is totally satisfactory. Bare metal ions, even when 
chelated, accelerate wasteful decomposition reactions that are non-bleach 
effective. Under alkaline conditions, such as in laundry cleaning 
compositions, metal ions undergo irreversible oxidation. Perversely, the 
peroxide bleaching reaction is most effective at high pH. Another concern 
with soluble metal ion systems is the potential for ion deposition onto 
the fabric. Discoloration of fabric can occur where deposited metal ions 
undergo subsequent oxidation. Finally, the prior art metal ion catalysts 
are sensitive to water hardness. Their activity varies with the calcium 
and magnesium content of the water source. 
Manganese (II) has been reported to be exceptionally effective in 
activating persalts under mild conditions. European Patent Application No. 
0 082 563 discloses bleach compositions containing manganese (II) in 
conjunction with carbonate compounds. British Patent Application No. 82 
36,005 describes manganese (II) in conjunction with a condensed 
phosphate/orthophosphate and an aluminosilicate as a bleach activator 
system. European Patent Application No. 0 025 608 reveals a peroxide 
decomposition catalyst consisting of acid treated zeolites or silicates 
whose cations have been exchanged for heavy metals such as manganese. 
All the aforementioned activator systems still suffer from the presence of 
soluble manganese (II) ions. The soluble ions deposit on fabrics. Strong 
oxidants, such as hypochlorites, are frequently included in laundry 
washes. Deposited manganese will react to form highly staining manganese 
dioxide. 
Consequently, it is an object of the present invention to provide a persalt 
manganese bleach activator that will not result in laundry staining. 
A further object of this invention is to provide a process for the 
preparation of the manganese bleach activator. 
Another object of this invention is to provide a laundry bleaching 
composition. 
SUMMARY OF THE INVENTION 
A catalyst for the controlled decomposition of peroxy compounds is provided 
comprising a water-soluble manganese (II) salt adsorbed onto a solid 
inorganic silicon support material, the combination having been prepared 
at a pH from 7.0 to 11.1. 
Furthermore, a process for the preparation of a catalyst for the controlled 
decomposition of peroxy compounds is disclosed comprising: 
(a) dissolving a water-soluble manganese (II) salt and a solid silicon 
support material in a solvent, the ratio of manganese (II) to solid 
silicon support material ranging from 1:1000 to 1:10; 
(b) adjusting pH to achieve a value from 7.0 to 11.1; 
(c) separating the solid composition; 
(d) washing the solid composition with solvent to remove any traces of free 
manganese (II) salts; and 
(e) drying the solid composition to remove solvent and mositure. 
An alternate process for the preparation of the above catalyst, where the 
amount of manganese (II) does not exceed the adsorptive capacity of the 
solid silicon support material, involves dissolving a water soluble 
manganese (II) salt and a solid silicon support material in a solvent and 
subsequently spray-drying the slurry. 
DETAILED DESCRIPTION OF THE INVENTION 
It has been found that by binding water-soluble manganese (II) ions onto an 
insoluble solid support, free manganese dioxide will not subsequently 
form. Fabric staining problems are thereby overcome. To achieve this 
result, the catalyst must be prepared in the manner herein prescribed. The 
resultant catalyst will (1) not release free manganese ions into the wash 
solution during use; (2) possess acceptable activity; and (3) have a 
satisfactory physical appearance. 
In the method of catalyst preparation, the key parameter is control of pH 
during the adsorption of manganese onto the solid support material. 
Manganese adsorption increases dramatically with increased pH. The pH may 
range from 7.0 to 11.1. Preferably, adsorption should take place between 
pH 8.0 and 10.5; at pH above 10.5 the resultant catalyst begins to develop 
an unpleasant brown appearance. 
Finished catalysts may be recovered in various ways subsequent to 
equilibration of solid support with manganese solution. Simple filtration 
of solids is one separation method. Copious quantities of fresh water or 
alcohol solvent must be used to wash the solid catalyst. The washing step 
is critical. Loosely bound or free manganese is thereby eliminated 
preventing microcrystalline manganese (II) salts from forming. Drying is 
necessary to eliminate bound water from the solid material. Removal of 
water is accomplished by drying between 100.degree. C. and 250.degree. C. 
Bound water can affect storage stability of the persalt-catalyst 
combination. Water content must be kept below 10 % in the final catalyst. 
Another method of preparation is blending manganese and the support 
material using an amount of manganese salt which does not exceed the 
adsorptive capacity of the solid. After adsorption, the content of free 
manganese salt in solution will be negligible. Removal of water is here 
most easily accomplished by spray-drying the slurry. 
The manganese used in the present invention can be derived from any 
manganese (II) salt which delivers manganous (II) ions in aqueous 
solution. Manganous sulfate and manganous chloride or complexes thereof 
such as manganous triacetate are examples of such suitable salts. 
The solid inorganic silicon support material has but one requirement--a 
capacity for manganous (II) adsorption greater than 0.1 weight %. Suitable 
solid materials encompass the aluminosilicates, including the 
synthetically formed variety known as zeolites, the silicates, silica gels 
and aluminas. Among the silicates, magnesium silicate is preferred; this 
material is sold by the Floridin Corp. under the trademark Florisil.TM.. 
Clays may also be suitable substrates. Two varieties of clay materials 
which function in the instant composition are geologically known as 
smectites (or montmorillonoides) and attapulgites (or palygorskites). 
Smectites are three-layered clays. There are two distinct classes of 
smectite-type clays. The first contains aluminum oxide, the second has 
magnesium oxide present in the silicate crystal lattice. General formulas 
for these smectites are Al.sub.2 (Si.sub.2 O.sub.5).sub.2 (OH).sub.2 and 
Mg.sub.3 (Si.sub.2 O.sub.5)(OH).sub.2, covering the aluminum and magnesium 
oxide type clays, respectively. Commercially available smectite clays 
include, for example, montmorillonite (bentonite), volchonskoite, 
nontronite, beidellite, hectorite, saponite, sauconite and vermiculite. 
Attapulgites are mangesium-rich clays having principles of superposition 
of tetrahedral and octahedral unit cell elements different from the 
smectities. An idealized composition of the attapulgite unit cell is given 
as: (OH.sub.2).sub.4 (OH).sub.2 Mg.sub.5 Si.sub.8 O.sub.20.4H.sub.2 O. 
Zeolites are the preferred support materials. Many commercial zeolites have 
been specifically designed for use in laundering applications. 
Accordingly, they exhibit the favorable properties of dispersivity in wash 
solution. Moreover, their tendency for being entrapped by fabrics is low. 
Synthetic zeolites are preferred over the natural ones. The latter have an 
appreciable content of extraneous metal ions that may promote wasteful 
peroxide decomposition reactions. 
Finished catalyst will contain from about 0.1% to about 5.5% manganese (II) 
per weight of solid support. Preferably, the amount of manganese (II) is 
from about 1to about 2.5%. 
These peroxy compound activators are incorporated into laundry bleach 
compositions. Besides activator, these compositions comprise a peroxide 
source and phosphate stabilizer. Suitable peroxy compounds include the 
inorganic persalts which liberate hydrogen peroxide in aqueous solution. 
These include water-soluble perborates, percarbonates, perphosphates, 
persilicates, persulfates and organic peroxides. Amounts of peroxy 
compound in the dry bleach powder should range from about 5 to about 30%. 
At least 30 ppm active oxygen should be delivered by the persalt. For 
instance, with sodium perborate monohydrate, this represents a minimum 
amount of 200 mg per liter of wash solution. 
The catalyst should deliver a miniumum level of 0.5 ppm manganese to the 
wash. For instance, if a catalyst has 1 weight % of manganese then at 
least 5 grams catalyst per liter of wash solution is required. 
Phosphate stabilizers are suggested for combination with the dry bleach 
powders. Suitable stabilizers include the alkali metal salts of 
tripolyphosphate, orthophosphate and pyrophosphate. Amounts of phosphate 
stabilizer should range from about 5% to about 35 %. Preferably, they 
should be present from about 10% to 15%. 
Surface active detergents may be present in an amount from about 2% to 50% 
by weight, preferably from 5% to 30% by weight. These surface active 
agents may be anionic, nonionic, zwitterionic, amphoteric, cationic or 
mixtures thereof. 
Among the anionic surfactants are water-soluble salts of alkylbenzene 
sulfonates, alkyl sulfates, alkyl ether sulfates, paraffin sulfonates, 
.alpha.-olefin sulfonates, .alpha.-sulphocarboxylates and their esters, 
alkyl glycerol ether sulfonates, fatty acid monoglyceride sulfates and 
sulfonates, alkyl phenol polyethoxy ether sulfates, 
2-acyloxy-alkane-1-sulfonates and .beta.-alkoxyalkane sulfonates. Soaps 
are also preferred anionic surfactants. 
Nonionic surfactants are water-soluble compounds produced by the 
condensation of ethylene oxide with a hydrophobic compound such as 
alcohol, alkyl phenol, polypropoxy glycol or polypropoxy ethylene diamine. 
Cationic surface active agents include the quaternary ammonium compounds 
having 1 or 2 hydrophobic groups with 8-20 carbon atoms, e.g., cetyl 
trimethylammonium bromide or chloride, dioctadecyl dimethylammonium 
chloride, and the fatty alkyl amines. 
A further exposition of suitable surfactants for the present invention 
appears in "Surface Active Agents and Detergents", by Schwartz, Perry & 
Berch (Interscience, 1958), the disclosure of which is incorporated herein 
by reference. 
Detergent builders may be combined with the bleach compositions. Useful 
builders can include any of the conventional inorganic and organic 
water-soluble builder salts. 
Typical of the well known inorganic builders are the sodium and potassium 
salts of the following: pyrophosphate, tripolyphosphate, orthophosphate, 
carbonate, bicarbonate, silicate, sesquicarbonate, borate and 
aluminosilicate. 
Among the organic detergent builders that can be used in the present 
invention are the sodium and potassium salts of citric acid and 
nitrilotriacetic acid. 
These builders can be used in an amount from 0 up to about 80% by weight of 
the composition, preferably from 10% to 50% by weight. 
Apart from detergent active compounds and builders, compositions of the 
present invention can contain all manner of minor additives commonly found 
in laundering or cleaning compositions in amounts in which such additives 
are normally employed. Examples of these additives include: lather 
boosters, such as alkanolamides, particularly the monoethanolamides 
derived from palm kernel fatty acids and coconut fatty acids; lather 
depressants, such as alkyl phosphates, waxes and silicones; fabric 
softening agents; fillers; and usually present in very minor amounts, 
fabric whitening agents, perfumes, enzymes, germicides and colorants.

The following examples will more fully illustrate the embodiments of the 
invention. All parts, percentages and proportions referred to herein and 
in the appended claims are by weight unless otherwise indicated. 
EXAMPLE 1 
Catalyst Preparation 
A total of 2.5 grams of manganous chloride tetrahydrate was dissolved in 50 
ml of distilled water. A separate vessel was charged with a slurry of 50 
grams zeolite (Union Carbide ZB-300) and 250 ml of water. The slurry pH 
was adjusted with either sodium hydroxide or hydrochloric acid solutions 
to the appropriate pH (see Table I). Zeolite slurry and manganous chloride 
solution were combined and stirred for at least 20 minutes. The solid was 
then filtered, washed with water, and dried at 110.degree. C. for 12 
hours. 
EXAMPLE 2 
A bleach composition was formulated comprising: 
______________________________________ 
Component Weight (grams) 
______________________________________ 
Sodium perborate monohydrate 
0.45 
Sodium tripolyphosphate 
0.20 
Sodium carbonate 0.30 
Sodium pyrophosphate 0.10 
Sodium linear C.sub.10 -C.sub.15 alkylbenzene 
0.20 
sulfonate 
Example 1 catalyst -- 
______________________________________ 
Bleaching tests were conducted with a 4 pot tergotometer from the U.S. 
Testing Company. Wash solutions were prepared from distilled water with 
hardness ions added to provide 80 ppm calcium and 40 ppm magnesium. Sodium 
hydroxide was used to elevate the pre-wash pH to about 10.9. The wash 
volume was 1 liter. Temperature was maintained at 40.degree. C. Agitation 
was provided throughout the 14 minute wash period. 
Bleaching was monitored by measuring reflectance of a dry cotton cloth 
(4".times.6"). Prior to bleaching, the cloth had been uniformly stained 
with a tea solution and washed several times in a commercial detergent. 
Reflectance was measured on a Gardner XL-23 reflectometer. 
To the aforementioned bleach composition were added varying amounts of 
bleach catalyst having been prepared at various pH levels as outlined in 
Table I below. Higher reflectance changes signify greater bleach 
effectiveness. 
TABLE I 
______________________________________ 
Effect of Catalyst Preparation and Concentration 
pH 
of Zeolite Slurry 
Catalyst Amount, gm. 
Reflectance Change 
______________________________________ 
5.0 0 2.8 
5.0 0.05 3.5 
5.0 0.10 3.7 
5.0 0.15 4.4 
7.0 0 2.15 
7.0 0.05 8.82 
7.0 0.10 11.54 
7.0 0.15 12.97 
9.0 0 3.03 
9.0 0.05 10.07 
9.0 0.10 11.70 
9.0 0.15 12.28 
______________________________________ 
Where catalyst was prepared at pH 5, the bleach activity was quite poor as 
seen in the low reflectance numbers. Catalysts prepared at pH 7 and above, 
however, demonstrated a significant increase in bleach activity. 
EXAMPLE 3 
Inorganic phosphates stabilize the bleach compositions of the present 
invention. A base composition was prepared comprising 0.35 grams of sodium 
perborate monohydrate and 0.08 grams of a 1.5% manganese on zeolite 
catalyst (Union Carbide's ZB-100). In preparing the catalyst, the zeolite 
was treated with sodium hydroxide to obtain a solution pH of 10.7. Various 
amounts sodium tripolyphosphate were blended with the base composition. 
Tea stained swatches were bleached with these compositions in a 
tergotometer. Bleach effectiveness was measured by the swatch reflectance 
changes. These results are recorded in Table II. 
TABLE II 
______________________________________ 
Sodium Tripolyphosphate (g) 
Reflectance Change 
______________________________________ 
0 1.75 
0.05 4.58 
0.10 6.32 
0.15 6.29 
0.20 6.07 
0.30 5.18 
0.40 1.80 
______________________________________ 
From Table II it appears that sodium tripolyphosphate present from 0.05 to 
0.30 grams per liter wash solution stabilized the bleach reactions. 
EXAMPLE 4 
This example illustrates the effectiveness of catalysts incorporating metal 
ions other than manganese on solid silicon support materials. According to 
this invention, metal ions were adsorbed onto zeolite (Union Carbide 
ZB-400). They were prepared in a fashion similar to that described in 
Example 1. These catalysts were blended into a bleach composition composed 
of: 
______________________________________ 
Components Weight (grams) 
______________________________________ 
Sodium perborate monohydrate 
0.4 
Sodium carbonate 0.4 
Sodium tripolyphosphate 
0.3 
Linear C.sub.10 -C.sub.15 alkylbenzene 
0.2 
sulfonate 
Catalyst 0.1 
______________________________________ 
p The wash solutions for this composition contained 80 ppm calcium and 40 
ppm magnesium. Sodium hydroxide was used to raise the pH of the wash 
solution to 10.7. Table III outlines the effectiveness of various metal 
ions. Manganese (II) was found to be far superior to cobalt, copper and 
iron impregnated zeolite. 
TABLE III 
______________________________________ 
Metal Ion Reflectance Change 
______________________________________ 
Cobalt (II) 1.90 
Copper (II) -4.0 
Iron (III) -2.7 
Manganese (II) 
10.7 
______________________________________ 
The foregoing description and examples illustrate selected embodiments of 
the present invention and in light thereof variations and modifications 
will be suggested to one skilled in the art, all of which are in the 
spirit and purview of this invention.