WO2000055291A1

WO2000055291A1 - Stabilizer for bleach-containing cleaners

Info

Publication number: WO2000055291A1
Application number: PCT/US2000/006898
Authority: WO
Inventors: Eva Day; Marian Andersson
Original assignee: R.T. Vanderbilt Company, Inc.
Priority date: 1999-03-17
Filing date: 2000-03-16
Publication date: 2000-09-21
Also published as: AR022976A1; AU3888500A

Abstract

The present invention provides extended stability hypochlorite compositions comprising a water-soluble, alkali or alkaline earth hypochlorite and a smectite clay. Methods for extending the stability of a hypochlorite solution are also provided.

Description

STABILIZER FOR BLEACH-CONTAINING CLEANERS

SPECIFICATION

BACKGROUND OF INVENTION Alkali and alkaline earth hypochlorites (bleaches) are used in household, industrial and institutional cleaners because they are excellent oxidizing agents. As such, they are used in disinfectant and sanitizing cleaners to kill microorganisms, in hard surface cleaners to remove stains, and in automatic dishwasher detergents to oxidize organic soils and thereby facilitate their removal. These cleaners typically also contain supplemental ingredients to optimize their cleaning effectiveness, chemical stability, physical stability, rheology, and aesthetics. Added ingredients include surfactants, abrasives, pH buffering agents, sequestrants, thickening agents, suspending agents, colorants, perfumes, and the like. These additives must be chosen with care, however, as they must be bleach-stable. Bleach- stable means that they are not decomposed by the hypochlorite, and that they do not accelerate the natural decomposition of the hypochlorite.

Aqueous solutions of hypochlorite bleach have a finite useful lifetime since their chemical equilibrium favors dissociation into chloride and chlorate compounds. For example, sodium hypochlorite, the species most commonly used in cleaners, decomposes as follows: 3NaOCl → 2NaCl + NaClO₃ ( 1 )

A second reaction also occurs: 2NaOCl - 2NaCl + O₂t (2)

Reaction (2) is minor compared to reaction (1), but predominates in the presence of elemental metallic contamination. Several factors affect the chemical stability of hypochlorite solutions.

Stability is diminished with increase in hypochlorite concentration, electrolyte concentration, and temperature. Metal contamination (Fe, Cu, Ni, Co) or UV light also accelerates decomposition. Hypochlorite solutions are most stable between pH 11 and pH 13; stability diminishes beyond either end of this range, particularly at pH<9.

Several grades of sodium hypochlorite are readily available to the formulator of cleaning products. These are differentiated according to their residual salt content, since electrolyte concentration adversely affects hypochlorite stability. Salt content thereby determines the length of time the hypochlorite is expected to provide the desired chemical activity.

Commercial sodium hypochlorite solution is most often produced by reacting chlorine with sodium hydroxide solution: 2C1₂ + 2NaOH → NaOCl + NaCl (3)

So-called "commodity" hypochlorite is made by this route and is sold with equimolar concentration of sodium hypochlorite and sodium chloride. The purity of the chlorine and caustic soda reactants directly affects the half-life of hypochlorite chemical activity. This is optimized by using high purity reactants, but it is still limited by the presence of the sodium chloride co-product. Hypochlorite activity is further extended by processes that remove up to 75% of the sodium chloride. The purest hypochlorites, those with the longest half-life, are produced by reacting an alkali or alkaline earth hydroxide with a solution of hypochlorous acid: NaOH + HOC1 - NaOCl + H₂O (4) Hypochlorite solutions prepared in this way are sold with up to 95% less salt than commodity hypochlorites.

Manufacturers requiring a long shelf life for their hypochlorite- containing cleaners have heretofore been required to use high priced, high purity bleach. The incorporation of smectite clays into hypochlorite-containing compositions have been found to unexpectedly retard hypochlorite decomposition, enabling further extension of shelf life when the highest purity bleaches are used, or allowing the use of inexpensive, commodity bleach. Moreover, it has been unexpectedly discovered that natural smectite clay is far superior to synthetic smectite clay for retarding bleach decomposition, despite the fact that the latter is of greater mineralogical and chemical purity. DETAILED DESCRIPTION OF THE INVENTION The present invention provides extended stability hypochlorite compositions comprising a water-soluble, alkali or alkaline earth hypochlorite and a smectite clay. The present compositions preferably have a pH of from about 11 to 13.

In one embodiment, the present compositions comprise a hypochlorite-compatible alkaline additive that maintains the composition in the pH 11 to pH 13 range.

Alternately or additionally, pH may be maintained by utilizing a buffered hypochlorite in the present compositions. The present invention further provides a method for extending the stability of a hypochlorite solution comprising admixing a smectite clay and a hypochlorite solution.

The smectite clays found useful as hypochlorite stabilizers include montmorillonite, hectorite, and saponite, as well as mixtures thereof. Smectite clays are also known in commerce by the generic names bentonite and magnesium aluminum silicate.

Smectite clays are characterized by their trilayer lattice structure and by their ability to hydraulically delaminate. There are two classes of smectite clay. In one, an aluminum based octahedral layer is sandwiched between two tetrahedral silica layers. A portion of the trivalent, octahedrally coordinated aluminum is substituted with divalent magnesium, and to a lesser degree with tri-and divalent iron. Limited substitution also occurs of the tetrahedral, tetravalent silicon with trivalent aluminum.

Montmorillonite is an example of smectite clay of this type.

In the other, a magnesium based octahedral layer is sandwiched between two tetrahedral silica layers. A portion of the divalent, octahedrally coordinated magnesium may be substituted with monovalent lithium, or a portion of the tetrahedral, tetravalent silicon is substituted with trivalent aluminum. Hectorite is characterized by the former, while the latter describes saponite.

Substitutions within the smectite crystal lattice leave a deficiency of positive charge, resulting in a net negative charge per smectite unit cell. This negative charge is balanced by associated cations at unit surfaces. Because these cations do not exist as an integral part of the lattice and are relatively easily replaced by other cations in aqueous dispersion, they are called the exchangeable cations.

These cations may be any alkali or alkaline earth element or blends thereof, although most commercially available smectites are either predominately sodium exchanged or predominately calcium exchanged. Smectites that are predominately sodium exchanged are more readily delaminated hydraulically and are capable of subsequently forming a three dimensional colloidal structure. This colloidal structure enables these smectites to be used as rheology control agents and as suspending agents. The ability of some smectite clays to perform this function is incidental to our discovery that smectite clays will retard hypochlorite decomposition. The ingredients in a preferred extended stability hypochlorite composition are a water-soluble, alkali or alkaline earth hypochlorite, refer to herein as "bleach", a hypochlorite-compatible alkaline additive that will maintain the composition in the pH 11 to pH 13 range, and a smectite clay. Preferred ingredients are sodium hypochlorite, sodium hydroxide, and a smectite clay of sufficient purity to preclude introduction of deleterious metallic contamination, such as may be present from wear on the milling equipment used to prepare the clay. Most preferred among the smectites are those natural varieties, or mixtures thereof, which have been water processed to minimize the presence of non-clay impurities. Other than metallic contaminants, non-clay impurities do not necessarily impede the ability of the clay to provide the desired bleach stabilization, but they may provide a dilution affect such that less smectite clay is present than desired. Preferred smectite clays useful in accordance with the present invention include VEEGUM® and VAN GEL® (R.T. Vanderbilt Co., Inc., Norwalk, CT). The absence of assayable iron or other bleach-degrading metals in the smectite clay is not strictly required as long as these metals are incorporated into the clay lattice structure and thereby unavailable to catalyze hypochlorite decomposition.

The present compositions may be made by admixing a hypochlorite solution and a smectite clay and, optionally, an alkaline additive. In a preferred embodiment of the compositions of the present invention, the hypochlorite is present at a concentration of about 0.01% to 35% (wt/wt). In a more preferred embodiment, the hypochlorite is present at a concentration of from about 0.5% to 7% (wt/wt). In another preferred embodiment, the smectite clay is present at a concentration of about 0.1% to 10% (wt/wt). In a more preferred embodiment, the smectite clay is present at a concentration of from about 1% to 5% (wt/wt). In another preferred embodiment, the alkaline additive is present at a concentration of from about 0.01% to 20% (wt/wt). In a more preferred embodiment, the alkaline additive is present at a concentration of from about 0.2% to 5% (wt/wt).

Optional additives may be included in these compositions in accordance with the desired application of the hypochlorite' s chemical activity. For example, bleach-stable surfactants may be added to facilitate contact and wetting of the surfaces to be cleaned with the hypochlorite. Several classes of bleach-stable surfactants are recognized, including certain alkali alkyl sulfates, amine oxides, and betaine surfactants, which are typically of the structure R₂R'N-R"COO— , where each R represents a lower alkyl group, R' represents a long chain alkyl group having from 8 to 22 carbon atoms and R" represents an alkylene group having 1 to 5 carbon atoms. A bleach-stable surfactant might be added to a hypochlorite composition to, for example, formulate a tile grout cleaner. A cleaner of this type would be designed to kill and remove mildew and associated stains from the grout between ceramic floor, wall, or ceiling tiles.

Fine, water-insoluble particulates may be added as abrasives in compositions such as liquid cleansers with bleach, in which they facilitate the physical removal of stains or strongly adhered soils. Typical abrasive materials would be finely ground varieties of calcium carbonate, silica, feldspar, diatomite, calcined kaolin, perlite and the like.

When abrasives are incorporated into cleaning compositions, it is common to also include a suspending agent to ensure that the abrasive particles remain uniformly dispersed and suspended during product storage. Certain of the smectite clays essential to the subject extended life hypochlorite solutions can also function as suspending agents. Other suspending agents used in bleach-containing compositions are attapulgite or sepiolite clays, amorphous silicas, and certain bleach- stable polymers. Using more than one suspending agent in combination sometimes optimizes suspension stability.

The suspending agents are, in some cases, also capable of functioning as rheology control agents, increasing the viscosity and modifying the flow properties of the composition. Rheology control is advantageous in cases where the cleaner must be applied to vertical surfaces and it is desired that the cleaner coat or otherwise remain in contact with the vertical surface for a time sufficient to allow the hypochlorite to provide the desired degree of activity.

Sequestrants, also known as detergent builders, are optionally added to improve cleaning effectiveness by chelating metal ions that contribute to water hardness (e.g. Ca²⁺, Mg²⁺). The sequestrants typically used in bleach-containing compositions, as in liquid automatic dishwasher detergents for example, include alkali phosphates, alkali pyrophosphates, alkali polyphosphates, alkali silicates, alkali metasilicates, and alkali carbonates. These compounds may also be used to supply the alkalinity required to maintain composition pH in the desired pH 11 to pH 13 range. Bleach-stable pigments, opacifiers, dyes, and perfumes may also be optionally added, particularly to improve the esthetics of compositions intended for household use. Other optional bleach-stable additives that are evident to anyone skilled in the art may also be used. The following non-limiting examples serve to further illustrate the present invention.

EXAMPLE I Tables 1 through 3 compare the stability of three grades of hypochlorite solution with and without the presence of 3% (w/w) montmorillonite. All preparations were adjusted to a pH suitable for promoting hypochlorite stability and were stored at 23 °C. These compositions contain a nominal 1% sodium hypochlorite, representing a level typical in cleaners for household use. BLEACH A¹ AT 1% Table 1

No Smectite 3% (w/ ) Smecti te Ml"

EH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.13 0.90 — 12.30 0.90 — l Week 12.14 0.91 0 12.22 0.89 1% 4 Weeks 1 1.95 0.86 4% 11.76 0.88 2% 8 Weeks 12.03 0.83 8% 11.66 0.87 3% 12 Weeks 12.19 0.74 18% 11.70 0.83 8% 24 Weeks 1 1.86 0.56 38% 11.41 0.68 24%

' 1 : lNaOCl:NaCl mole ratio (commodity bleach) ^alow cation exchange capacity montmorillonite

BLEACH B² AT 1% Table 2

No Smectite 3% (w/w) Smectite Ml" fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.09 1.07 - 12.27 1.03 ~ 1 Week 12.13 1.07 0 12.22 1.05 0

4 Weeks 1 1.92 1.01 6% 1 1.78 1.03 0 8 Weeks 1 1.99 0.97 9% 1 1.65 1.02 1% 12 Weeks 12.08 0.88 18% 1 1.66 0.97 6% 24 Weeks 11.83 0.66 38% 1 1.41 0.80 22%

²3:lNaOCl:NaCl mole ratio

Mow cation exchange capacity montmorillonite

BLE ACH C³ AT l% Table 3 |

No Smectite 3% (w/w) Sme< :tite Ml" fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.04 1.17 — 12.30 1.15 — l Week 12.04 1.18 0 12.22 1.15 0 4 Weeks 11.85 1.09 7% 11.80 1.13 2% 8 Weeks 11.89 1.03 12% 1 1.64 1.12 3%

12 Weeks 12.02 0.94 20% 11.64 1.06 8% 24 Weeks 11.80 0.66 44% 11.36 0.87 24%

³19:lNaOCl:NaCl mole ratio

"low cation exchange capacity montmorillonite These tables demonstrate the smectite clay's ability to retard hypochlorite decomposition, regardless of the purity of the hypochlorite solution used.

EXAMPLE II Several smectite clays were compared as bleach stabilizers in compositions containing a relatively high concentration of commodity hypochlorite (Bleach A above), and also containing a common pigment/opacifier with and without a bleach-stable surfactant (Polytergent 2A1; Olin). The comparison formulas are:

Tables 4 through 6 show that the surfacant and opacifier, individually and in combination, are reasonably bleach-stable, but do not themselves improve hypochlorite stability. Table 4

FORMULA 1 FORMULA 2 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.75 ~ 12.54 3.75 ~ l Week 12.36 3.66 2% 12.44 3.55 5%

4 Weeks 12.43 3.42 9% 12.51 3.27 13%

8 Weeks 12.37 3.09 18% 12.39 3.00 20%

24 Weeks 12.42 1.81 52% 12.55 1.77 53%

Table 5

FORMULA 1 FORMULA 3 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.75 - 12.48 3.66 --

1 Week 12.36 3.66 2% 12.48 3.65 0

4 Weeks 12.43 3.42 9% 12.47 3.43 6%

8 Weeks 12.37 3.09 18% 12.39 3.11 15%

24 Weeks 12.42 1.81 52% 12.39 1.81 51%

Table 6

FORMULA 1 FORMULA 4 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.75 -- 12.49 3.66 ~ 1 Week 12.36 3.66 2% 12.54 3.56 3% 4 Weeks 12.43 3.42 9% 12.51 3.33 9% 8 Weeks 12.37 3.09 18% 12.43 3.05 17% 24 Weeks 12.42 1.81 52% 12.51 1.75 52%

Tables 7 through 1 1 compare Formula 3 to the same composition with several varieties of added smectite clay. In each case, hypochlorite stability is improved by the clay. Table 7

FORMULA 3 1 FORMULA 5

CΞ % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.66 - 12.50 3.69 -- l Week 12.48 3.65 0 12.36 3.69 0

4 Weeks 12.47 3.43 6% 12.34 3.58 3%

8 Weeks 12.39 3.11 15% 12.30 3.43 7%

24 Weeks 12.39 1.81 51% 12.36 2.96 20%

Table 8

FORMULA 3 FORMULA 7 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.66 - 12.44 3.68 —

1 Week 12.48 3.65 0 12.36 3.66 1%

4 Weeks 12.47 3.43 6% 12.32 3.53 4%

8 Weeks 12.39 3.11 15% 12.45 3.41 7%

24 Weeks 12.39 1.81 51% 12.44 2.85 22%

Table 9

FORMULA 3 FORMULA 9 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.66 — 12.38 3.66 ~ l Week 12.48 3.65 0 12.32 3.64 1%

4 Weeks 12.47 3.43 6% 12.30 3.52 4%

8 Weeks 12.39 3.11 15% 12.29 3.41 7%

24 Weeks 12.39 1.81 51% 12.33 2.90 21%

Table 10

FORMULA 3 FORMULA 11 fiH % NaOCl 1 VaOCI Loss fiH % NaOCl NaOCl Loss

Initial 12.48 3.66 -- 12.54 3.68 ~ l Week 12.48 3.65 0 12.16 3.62 2% 4 Weeks 12.47 3.43 6% 12.15 3.52 4% 8 Weeks 12.39 3.11 15% 12.20 3.43 7% 24 Weeks 12.39 1.81 51% 12.27 2.95 20% Table 11

FORMULA 3 FORMULA 13 fiH % NaOCl NaOCl Loss fiS % NaOCl NaOCl Loss

Initial 12.48 3.66 - 12.58 3.66 ~ l Week 12.48 3.65 0 12.32 3.64 1%

4 Weeks 12.47 3.43 6% 12.16 3.53 4%

8 Weeks 12.39 3.11 15% 12.20 3.42 7%

24 Weeks 12.39 1.81 51% 12.34 2.94 20%

Tables 12 through 16 compare Formula 4, with surfactant and opacifier, to the same composition with several varieties of added smectite clay. Once again, hypochlorite stability is improved by the clay.

Table 12

FORMULA 4 FORMULA 6 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.49 3.66 — 12.48 3.69 ~ l Week 12.54 3.56 3% 12.39 3.57 3% 4 Weeks 12.51 3.33 9% 12.41 3.46 6% 8 Weeks 12.43 3.05 17% 12.30 3.29 11% 24 Weeks 12.51 1.75 52% 12.32 2.64 28%

Table 13

FORMULA 4 FORMULA 8 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.49 3.66 ~ 12.48 3.68 — l Week 12.54 3.56 3% 12.39 3.52 4% 4 Weeks 12.51 3.33 9% 12.33 3.40 8% 8 Weeks 12.43 3.05 17% 12.41 3.20 13% 24 Weeks 12.51 1.75 52% 12.48 2.42 34% Table 14

FORMULA 4 FORMULA 1 0 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.49 3.66 — 12.42 3.66 —

1 Week 12.54 3.56 3% 12.33 3.56 3%

4 Weeks 12.51 3.33 9% 12.28 3.42 7%

8 Weeks 12.43 3.05 17% 12.37 3.25 11%

24 Weeks 12.51 1.75 52% 12.30 2.65 28%

Table 15

FORMULA 4 FORMULA 12 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.49 3.66 — 12.55 3.68 —

1 Week 12.54 3.56 3% 12.27 3.51 5%

4 Weeks 12.51 3.33 9% 12.15 3.40 8%

8 Weeks 12.43 3.05 17% 12.23 3.24 12%

24 Weeks 12.51 1.75 52% 12.26 2.70 27%

Table 16

FORMULA 4 FORMU LA 14 fiH % NaOCl VaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.49 3.66 ~ 12.48 3.66 ~ l Week 12.54 3.56 3% 12.29 3.52 4%

4 Weeks 12.51 3.33 9% 12.18 3.41 7%

8 Weeks 12.43 3.05 17% 12.26 3.25 1 1%

24 Weeks 12.51 1.75 52% 12.32 2.66 27%

EXAMPLE III The experiments described in Example II were repeated in part, with a reduced concentration of both hypochlorite and surfactant. The comparison formulas are:

Tables 17 through 19 show that the surfactant and opacifier, individually and in combination, are reasonably bleach-stable, but do not themselves improve hypochlorite stability.

Table 17

FORMULA 15 FORMULA 16 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.37 1.43 12.39 1.43 l Week 12.38 1.41 1% 12.42 1.40 2% 4 Weeks 12.41 1.34 6% 12.40 1.32 8% 8 Weeks 12.40 1.27 11% 12.40 1.23 14% 24 Weeks 12.40 0.89 38% 12.51 0.84 41%

Table 18

FORMULA 15 FORMULA 17

EH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.37 1.43 ~ 12.54 1.43 ~ 1 Week 12.38 1.41 1% 12.47 1.41 1% 4 Weeks 12.41 1.34 6% 12.44 1.36 5% 8 Weeks 12.40 1.27 11% 12.41 1.28 10% 24 Weeks 12.40 0.89 38% 12.50 0.88 38% Table 19

FORMULA 15 | FORMULA 18 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.37 1.43 ~ 12.45 1.43 -- l Week 12.38 1.41 1% 12.45 1.41 1%

4 Weeks 12.41 1.34 6% 12.46 1.31 8%

8 Weeks 12.40 1.27 11% 12.47 1.21 15%

24 Weeks 12.40 0.89 38% 12.50 0.79 45%

Tables 20 through 22 compare Formula 17 to the same composition with several varieties of added smectite clay. In each case, hypochlorite stability is improved by the clay.

Table 20

FORMULA 17 FORMULA 19 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCI Loss

Initial 12.54 1.43 - 12.43 1.42 —

1 Week 12.47 1.41 1% 12.29 1.42 0

4 Weeks 12.44 1.36 5% 12.26 1.39 2%

8 Weeks 12.41 1.28 10% 12.25 1.38 3%

24 Weeks 12.50 0.88 38% 12.32 1.29 9%

Table 21

FORMULA 17 FORMULA 21 fiH % NaOCI ] NaOCl Loss fiH % NaOCl NaOCI Loss

Initial 12.54 1.43 — 12.41 1.42 ~ 1 Week 12.47 1.41 1% 12.18 1.39 2% 4 Weeks 12.44 1.36 5% 12.12 1.39 2% 8 Weeks 12.41 1.28 10% 12.14 1.37 4% 24 Weeks 12.50 0.88 38% 12.17 1.28 10% Table 22

FORMULA 17 FORMULA 23 fiH % NaOCl NaOCI Loss fiH % NaOCl NaOCI Loss

Initial 12.54 1.43 — 12.45 1.41 — l Week 12.47 1.41 1% 12.27 1.40 1%

4 Weeks 12.44 1.36 5% 12.17 1.38 2%

8 Weeks 12.41 1.28 10% 12.15 1.36 4%

24 Weeks 12.50 0.88 38% 12.22 1.28 9%

Tables 23 through 25 compare Formula 18, with surfactant and opacifier, to the same composition with several varieties of added smectite clay. Once again, hypochlorite stability is improved by the clay.

Table 23

FORMULA 18 FORMULA , 20 fiH % NaOCl NaOCl Loss fiH % NaOCI NaOCl Loss

Initial 12.45 1.43 — 12.45 1.42 ~

1 Week 12.45 1.41 1% 12.23 1.40 1%

4 Weeks 12.46 1.31 8% 12.24 1.36 4%

8 Weeks 12.47 1.21 15% 12.26 1.33 6%

24 Weeks 12.50 0.79 45% 12.32 1.15 19%

Table 24

FORMULA 18 FORMULA 22 fiH % NaOCl NaOCI Loss fiH % NaOCl NaOCI Loss

Initial 12.45 1.43 - 12.45 1.42 ~ l Week 12.45 1.41 1% 12.21 1.38 3% 4 Weeks 12.46 1.31 8% 12.13 1.35 5% 8 Weeks 12.47 1.21 15% 12.17 1.32 7% 24 Weeks 12.50 0.79 45% 12.18 1.17 18% Table 25

FORMULA 18 FORMULA 24 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCI Loss

Initial 12.45 1.43 — 12.47 1.41 -- l Week 12.45 1.41 1% 12.26 1.39 1%

4 Weeks 12.46 1.31 8% 12.17 1.36 4%

8 Weeks 12.47 1.21 15% 12.14 1.34 5%

24 Weeks 12.50 0.79 45% 12.22 1.18 16%

EXAMPLE IV Synthetic smectite clay, typically synthetic hectorite, has in prior art been cited as a suitable suspending and/or thickening agent in hypochlorite-containing compositions. It has even been cited among the preferred smectites for these uses (e.g., U.S. Patents 4,512,908; 4,511,487; 1,437,857). Since the synthetic smectites are produced with high mineralogical purity (there are no other minerals present) and high chemical purity (reactants are chosen to avoid the inclusion of iron, copper, nickel, etc.), they would be expected to improve hypochlorite stability at least as well as natural smectites. It has been surprisingly discovered, however, that natural smectite is considerably more effective in enhancing hypochlorite stability. This is demonstrated in Table 26 where hypochlorite stability is compared in the presence of a natural smectite, Smectite Ml (as above), vs. a synthetic hectorite. These compositions were based on the following formula:

Water 94.9%

Smectite 3.0%

NaOH (100% basis) 0.5%

NaOCl (100% basis) 1.6%

(commodity bleach) Table 26

(NATURAL) SMECTITE Ml SYNTHETIC HE CTORITE fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCI Loss

Initial 12.52 1.57 — 12.50 1.57 --

4 Weeks 12.23 1.55 1% 12.49 1.53 3%

12 Weeks 12.11 1.51 4% 12.44 1.35 14%

28 Weeks 12.12 1.40 11% 12.58 1.06 32%

There is three times the hypochlorite loss in the presence of the synthetic smectite than when the natural smectite is used.

EXAMPLE V A commodity bleach was identified that had an unexpected high instability in the presence of certain levels of alkali. These were alkali concentrations that would otherwise be expected to promote hypochlorite stability by maintaining the hypochlorite solution in the optimal pH range. Table 27 shows the stability of this bleach at ambient temperature in the presence of several levels of sodium hydroxide. Even though 0.5% and 1.0% NaOH maintain solution pH in a range considered conducive to hypochlorite stability, the bleach actually shows poor stability. Table 28 demonstrates that natural smectite clay (a low cation exchange montmorillonite, as above) significantly improves the stability of this bleach in the presence of a concentration of alkali that otherwise allowed significant decomposition of the hypochlorite. Moreover, Table 28 shows that this natural smectite clay significantly improves the stability of this bleach even in the absence of any pH-adjusting alkali, even though the pH is below that conventionally believed required for good hypochlorite stability. Table 27

BLEACH D¹ AT 1.5%

No SMECTITE fiH % NaOCl NaOCl Loss

No NaOH

Initial 11.6 1.54 —

4 Weeks 1 1.6 1.40 9%

8 Weeks 11.5 1.27 18%

12 Weeks 11.6 1.16 25%

24 Weeks 11.4 0.79 49%

0.1% NaOH

Initial 12.4 1.54 —

4 Weeks 12.0 1.42 8%

8 Weeks 12.4 1.35 12%

12 Weeks 12.2 1.27 18%

24 Weeks 12.0 1.02 34%

0.5% NaOH

Initial 12.8 1.53 —

4 Weeks 12.4 0.86 44%

8 Weeks 12.5 0.55 64%

12 Weeks 12.6 0.39 75%

24 Weeks 12.4 0.17 89%

1.0% NaOH

Initial 12.7 1.53 —

4 Weeks 12.6 0.88 43%

8 Weeks 12.6 0.55 64%

12 Weeks 12.8 0.39 75%

24 Weeks 12.6 0.15 90%

5.0% NaOH

Initial 12.8 1.53 —

4 Weeks 12.7 1.39 9%

8 Weeks 12.8 1.26 18%

12 Weeks 13.0 1.12 27%

24 Weeks 12.8 0.74 52%

10.0% NaOH

Initial 12.5 1.49 —

4 Weeks 12.6 1.30 13%

8 Weeks 12.7 1.15 23%

12 Weeks 12.8 1.02 32%

24 Weeks 12.7 0.66 56%

' commodity bleach

BLEACH D AT 1.5% Table 28 j

No Smectite 3 % (w/w) Sm ectite Ml" fiH % NaOCI NaOCl Loss fiH % NaOCl NaOCI Loss

No NaOH

Initial 11.6 1.54 — 11.0 1.52 --

4 Weeks 11.6 1.40 9% 10.4 1.47 3%

8 Weeks 11.5 1.27 18% 10.2 1.43 6%

12 Weeks 11.6 1.16 25% 10.3 1.40 8%

24 Weeks 11.4 0.79 49% 10.2 1.28 16%

0.5% NaOH

Initial 12.8 1.53 — 12.6 1.47 ~

4 Weeks 12.4 0.86 44% 12.2 1.46 1%

8 Weeks 12.5 0.55 64% 12.1 1.43 3%

12 Weeks 12.6 0.39 75% 12.1 1.41 4%

24 Weeks 12.4 0.17 89% 12.0 1.27 14%

low cation exchange capacity montmorillonite

EXAMPLE VI Because UV light is known to decompose soluble hypochlorites, compositions were prepared with and without smectite clay to determine if the stabilizing effect of the clay is due simply to its opacifying affect on the hypochlorite solution. These compositions were based on the following formula: Water q.s. to 100% NaOH (100% basis) 0.5% NaOCl (100% basis) 1.5% (Bleach D)

Each composition was divided such that half was stored on a laboratory bench top, exposed to light, and the remainder was stored in a closed dark cabinet. Table 29 shows that storage in the dark did not improve the stability of the hypochlorite solution, while the inclusion of the smectite clay significantly improved hypochlorite stability, whether stored in the dark or with exposure to light. The stabilization of hypochlorite is not due simply to its opacification of the hypochlorite solution. Table 29

No Smectite 3% (w/w) Sn lectite Ml"

EH % NaOCl NaOCl Loss % NaOCl NaOCl Loss

Light Storage

Initial 12.7 1.47 ~ 12.6 1.47 ~

4 Weeks 12.5 0.93 37% 12.2 1.46 1%

8 Weeks 12.5 0.63 57% 12.1 1.43 3%

12 Weeks 12.5 0.46 69% 12.1 1.41 4%

24 Weeks 12.4 0.17 88% 11.9 1.27 14%

Dark Storage

Initial 12.7 1.46 ~ 12.6 1.46 ~

4 Weeks 12.5 1.02 30% 12.2 1.47 0%

8 Weeks 12.5 0.72 51% 12.2 1.47 0%

12 Weeks 12.5 0.53 64% 12.1 1.44 1%

24 Weeks 12.4 0.20 86% 11.9 1.41 3%

low cation exchange capacity montmorillonite

EXAMPLE VII Bleach-stable polyacrylate-type thickeners are used to add yield value to hypochlorite compositions for suspension of abrasives or stabilization of emulsions. These thickeners are also used to impart viscosity in order to provide, for example, improved coating and adhesion on vertical surfaces. While sold as bleach-stable, they do not improve hypochlorite stability, as do the smectite clays. Tables 30 to 35 demonstrate the improved stability from the addition of smectite clay to polyacrylate thickened bleach compositions, as reflected in results from high-temperature accelerated aging at 50 °C. The comparison formulas are:

Formula 25 1.5% NaOCl ( 100% basis) (Bleach D)

1.0% Polyacrylate

NaOH (100% basis) q.s. to pH 12.5 q.s. to 100% Water Formula 26 Formula 25 with Carbopol® 672 Formula 27 Formula 25 with Carbopol® 676 Formula 28 Formula 25 with Polygel DA Formula 29 Formula 26 with 3% Smectite M 1 Formula 30 Formula 27 with 3% Smectite Ml Formula 31 Formula 28 with 3% Smectite Ml Formula 32 Formula 26 with 2% surfactant Formula 33 Formula 27 with 2% surfactant Formula 34 Formula 28 with 2% surfactant Formula 35 Formula 29 with 2% surfactant Formula 36 Formula 30 with 2% surfactant Formula 37 Formula 31 with 2% surfactant

Table 30

FORMULA 26 FORMULA 2 9 fiH % NaOCl NaOCl Loss fiH % NaOCI NaOCl Loss

Initial 12.6 1.48 — 12.6 1.53

4 Weeks, RT 12.5 1.09 26% 12.4 1.50 2%

4 Weeks, 50 °C 12.6 0.90 39% 12.4 1.27 17%

Table 31

FORMULA 27 FORMULA 3 0 fiH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.7 1.47 — 12.5 1.49

4 Weeks, RT 12.6 1.07 27% 12.4 1.43 4%

4 Weeks, 50°C 12.5 0.89 39% 12.4 1.16 22% Table 32

FORMULA 28 FORMULA 31 pH % NaOCI NaOCI Loss fiH % NaOCl NaOCl Loss

Initial 12.6 1.47 — 12.5 1.48

4 Weeks, RT 12.6 1.07 27% 12.5 1.43 3%

4 Weeks, 50 °C 12.5 0.88 40% 12.4 1.08 27%

Table 33

FORMULA 32 FORMULA 35

DH % NaOCl NaOCl Loss fiH % NaOCl NaOCl Loss

Initial 12.5 1.48 ~ 12.6 1.53

4 Weeks, RT 12.5 1.09 26% 12.5 1.35 12%

4 Weeks, 50 °C 12.6 0.74 50% 12.4 1.10 28%

Table 34

FORMULA 33 FORMULA 36 fiH % NaOCl NaOCl Loss fiH % NaOCI NaOCl Loss

Initial 12.7 1.47 — 12.5 1.49

4 Weeks, RT 12.5 1.08 27% 12.4 1.44 3%

4 Weeks, 50 °C 12.5 0.79 46% 12.4 1.00 33%

Table 35

FORMULA 34 FORMULA 37

DH % NaOCl NaOCI Loss fiH % NaOCl NaOCI Loss

Initial 12.6 1.47 — 12.5 1.48

4 Weeks, RT 12.5 1.03 30% 12.5 1.40 5%

4 Weeks, 50 °C 12.5 0.73 50% 12.4 0.95 36%

Claims

1. A composition comprising a water-soluble, alkali or alkaline earth hypochlorite and a smectite clay.

2. The composition of Claim 1 further comprising a hypochlorite- compatible alkaline additive that maintains the pH of the composition at from 1 1 to 13.

3. The composition of Claim 1 having a pH of from about 1 1 to 13.

4. The composition of Claim 1- wherein the smectite clay is a natural smectite.

5. The composition of Claim 1 wherein the smectite clay is montmorillonite, hectorite, saponite, or a mixture thereof.

6. The composition of Claim 1 wherein the hypochlorite is sodium hypochlorite.

7. The composition of Claim 2 wherein the alkaline additive is sodium hydroxide.

8. The composition of Claim 1 wherein the hypochlorite is present at a concentration of about 0.01% to 33% (wt/wt).

9. The composition of Claim 1 wherein the hypochlorite is present at a concentration of about 0.5% to 7% (wt/wt).

10. The composition of Claim 1 wherein the smectite clay is present at a concentration of about 0.1 % to 10% (wt/wt).

11. The composition of Claim 1 wherein the smectite clay is present at a concentration of about 1% to 5% (wt/wt).

12. The composition of Claim 2 wherein the alkaline additive is present at a concentration of about 0.01% to 20% (wt/wt).

13. The composition of Claim 2 wherein the alkaline additive is present at a concentration of about 0.2% to 5% (wt/wt).

14. The composition of Claim 1 further comprising a bleach-stable surfactant.

15. The composition of Claim 1 further comprising an abrasive.

16. The composition of Claim 15 further comprising a suspending agent.

17. The composition of Claim 1 further comprising a sequestrant.

18. A composition comprising sodium hypochlorite, sodium hydroxide and a smectite clay.

19. A method for extending the stability of a hypochlorite solution comprising admixing a smectite clay and an alkali or alkaline earth hypochlorite solution.

20. The method of Claim 19 wherein the solution has a pH from 1 1 to 13.

21. The method of Claim 19 wherein said hypochlorite solution is a sodium hypochlorite solution.

22. The method of Claim 19 wherein said smectite clay is montmorillonite, hectorite, saponite, or a mixture thereof.