CN1102649C - Pigmented rheopectic cleaning compositions with thioxotropic properties - Google Patents

Abstract

A pigmented bleach-containing hard surface cleaner comprises an alkali metal hypochlorite, bentonite clay, a mono-(long chain alkyl)-tertiary amine oxide, an alkali metal salt, a pH stabilizer to attain a pH of 11 or higher, an alkali metal alkyl sarcosinate, an alkylbenzene sulphonate, and an inorganic pigment which is preferably ultramarine blue. The cleaning composition has excellent colour stability as well as phase stability and hypochlorite stability.

Description

Colored rheological cleaning composition with thixotropic properties

field of invention

The present invention relates to viscous liquid bleach-containing compositions for hard surface cleaning, and more particularly to compositions including bleach-stable pigments.

Background of the invention

Viscous bleaching compositions have several advantages over non-viscous bleaching compositions. Relatively more viscous, thicker liquids can adhere to vertical and inclined surfaces for a longer period of time, or the disinfecting activity of viscous compositions can be more effective on the applied area.

In order to achieve an acceptable shelf life for a viscous hypochlorite composition, the rate of decomposition of the alkali metal hypochlorite as well as the phase properties of the composition must be considered. As is known, the degradation of alkali metal hypochlorite can be represented by the following equilibrium:

Many conventional thickeners accelerate the degradation of hypochlorite and are therefore problematic for use in hypochlorite compositions. Also, adding conventional thickeners and surfactants is difficult because the resulting hypochlorite composition can separate into two or more phases, especially at high temperatures. Many thickeners are also inherently unstable in the presence of alkali metal hypochlorites. Therefore, it is difficult to achieve sufficient viscosity and acceptable stability of hypochlorite compositions by conventional reagents and additives.

From a commercial and aesthetic point of view it is still desirable to provide viscous compositions which contain bleach and are visibly colored. Bleach-stable pigments are rare because organic pigments degrade in the presence of strong oxidizing agents.

US Patent 4,474,677 (Foxlee) proposes the use of certain copper halide phthalocyanine pigments in aqueous alkali metal hypochlorite compositions. Although these pigments are considered bleach-stable, the slow degradation of the pigment molecules releases copper, which catalyzes the degradation of hypochlorite. US Patent 4,271,030 (Brierley) describes a suspension of ultramarine blue using a calcium soap flocculant. The use of calcium soap flocculants is undesirable because of higher concentration requirements, up to 50% by volume of the composition, or because of deposits on hard surfaces from a cleaning standpoint. US Patent 4,952,333 (Cramer) describes bleach lightening compositions using polymers to suspend ultramarine blue in an emulsified polymer matrix. However, this composition is ineffective on hard surfaces due to its poor stain release. US Patent 4,917,814 (MacIntyre) describes the use of cobalt aluminate to dye viscous hypochlorite solutions. From the perspective of suspension performance, cobalt pigment is better than ultramarine blue. Although not discussed here, it should be noted that at higher temperatures than those employed by MacIntyre, the surfactant viscous composition will lose its viscosity and allow the pigment to settle. The final product requires stability when exposed to these higher temperatures during shipping and storage.

Summary of the invention

The present invention provides viscous hypochlorite compositions having enhanced rheological properties which can stably suspend inorganic pigments. The viscous system is a blend of surfactants and clays that are rheological at low shear rates to help stabilize suspended pigments, but thixotropic at higher shear rates , allowing the product to be easily dispensed from the container to help clean hard surfaces. By definition, rheology and thixotropy are opposite flow properties. It is quite advantageous to have both properties in one fluid.

Non-limiting examples of inorganic pigments that can be used include ultramarine blue cobalt aluminate, titanium dioxide, and calcium carbonate. The present invention primarily uses ultramarine blue, which is preferred because of its consumer appeal, low toxicity and color density compared to other pigments.

The composition behaves like a highly structured liquid and has unique and unexpected flow properties. These properties are exhibited even at low solids levels, less than 10% of the composition, compared to other structured liquids. Other known structured liquids are liquid laundry detergents. This characteristic helps to solve the problem of pigment settling, but at the same time maintains the flowing properties of a thin fluid, which helps products such as liquid basin cleaners achieve good surface coverage. The composition also has good phase stability and hypochlorite stability.

The composition of the present invention comprises: (a) an alkali metal hypochlorite, preferably sodium hypochlorite, (b) bentonite, (c) a tertiary amine having a long chain alkyl group of 10-16 carbon atoms and two lower alkyl groups Oxides, (d) alkali metal salts, preferably sodium chloride, (e) pH stabilizers to keep the pH at 11 or higher, (f) alkali metal _C10 - _C16 alkyl sarcosinates, (g) C ₁₀ -C ₁₄ linear alkylbenzene sulfonate, and (h) an inorganic pigment, preferably ultramarine blue. The desirable rheological properties and phase stability described above can be achieved by blending clays, surfactants and electrolytes. Specifically, the molar ratio of tertiary amine oxide (c) to alkylbenzene sulfonate (g) is from about 5:1 to about 11:1. Useful unpigmented compositions similar to the present invention can be prepared without the use of pigment (h).

The viscosity of the composition ranges from about 200 to about 1000 cps. A preferred range is about 300-500 cps.

Brief description of the drawings

Figures 1 and 2 are graphs showing the rheological properties of a preferred embodiment of the invention.

Figures 3 and 4 are graphs showing certain rheological properties of a composition according to the invention (Figure 3) and comparative properties of a similar composition without clay (Figure 4).

A detailed description

The compositions of the present invention are hypochlorite-stable, single-phase, viscous hypochlorite bleach compositions that adhere to vertical or inclined surfaces for longer periods of time than thinner compositions. The composition is an agent effective for stain and soil removal and disinfection. The high level of hypochlorite stability and single solution phase nature of the composition allows for an acceptable shelf life. The composition also includes an organic pigment in suspension. In these colored compositions, color stability, especially when ultramarine blue is used as pigment, is very advantageous.

The alkali metal in the alkali metal hypochlorite is preferably selected from: lithium, potassium or sodium. Sodium hypochlorite is preferred in terms of cost and availability. Alkali metal hypochlorites can produce other by-products during the preparation process, but do not negatively affect the composition. The amount of alkali metal hypochlorite used is about 0.5wt%-10wt%, preferably about 1.0wt%-5.0wt%, more preferably about 1.5wt%-3.0wt%.

Bentonite is a colloidal hydrated alumina silicate clay found in North America. Its basic composition is montmorillonite (Al ₂ O ₃ .4SiO ₂ .H ₂ O) and usually contains magnesium, iron and calcium carbonate. Bentonite clay is preferred for use in the compositions of the present invention, but other clays of similar structure and/or properties may also be used. Bentonite is used in the composition in an amount of about 0.15 wt% to 1.5 wt%, preferably about 0.25 wt% to 1.0 wt%. The structural formula of tertiary amine oxide is: Wherein, R ¹ is an alkyl group containing about 10-16 carbon atoms, and R ² and R ³ are lower alkyl groups containing 1-3 carbon atoms. R ¹ , R ² and R ³ may be linear or branched; R ¹ contains an odd or even number of carbon atoms. Mixed chain length amine oxides may be used, which may comprise a majority of one or more chain lengths. Preferably, the tertiary amine oxide is selected from the group consisting of tetradecyldimethylamine oxide, dodecyldimethylamine oxide, and mixtures thereof. Most preferably used is tetradecyldimethylamine oxide. The tertiary amine oxide is preferably used in an amount of about 0.5 wt% to 2.5 wt%, more preferably about 0.9 wt% to 1.8 wt%, most preferably about 1.0 wt% to 1.5 wt%.

The alkali metal salt can be selected from a number of water soluble alkali metal salts and mixtures thereof, wherein the alkali metal is preferably lithium, potassium or sodium and the anion is preferably a halide ion (such as chlorine, fluorine, bromine and iodide). More preferred alkali metal salts are selected from sodium chloride, lithium chloride, potassium chloride and mixtures thereof. From the perspective of cost and availability, the alkali metal salt is most preferably sodium chloride, and can be used in various amounts to reduce the degradation of hypochlorite, but only limited to avoiding salt precipitation in solution (at this time, the surfactant becomes insoluble in water). When sodium chloride is used, it is preferably used in an amount of about 0.25 wt% to 2.0 wt%, more preferably about 0.5 wt% to 1.5 wt%.

Alkali metal hydroxides are the preferred pH stabilizers to include in the composition, but a variety of pH stabilizers can be used as long as they do not adversely affect the stability and viscosity of the composition. Other pH stabilizers that may be used include, for example, carbonate buffers. The preferred alkali metal for the hydroxide may be lithium, potassium or sodium. Sodium hydroxide and potassium hydroxide are particularly preferred pH stabilizers due to cost and availability, with sodium hydroxide being the most preferred. The amount of alkali metal hydroxide included in the composition is an amount effective to adjust the pH of the composition to at least 11, more preferably 12-13.5, most preferably 12-13.

Alkali metal alkyl sarcosinates can be represented by the following structural formula: Wherein, R ⁴ is a branched or linear C ₁₀ -C ₁₆ alkyl group, and M is an alkali metal cation (such as lithium, potassium or sodium). Sodium lauroyl sarcosinate is most preferred. The alkali metal alkyl sarcosinate is preferably used in an amount of about 0.10 wt %-0.75 wt %, more preferably about 0.12 wt %-0.60 wt %, most preferably about 0.15 wt %-0.30 wt %.

The alkali metal C ₁₀ -C ₁₄ linear alkylbenzene sulfonates are preferably those in which the alkali metal is potassium, lithium or sodium. Most preferably used is sodium dodecylbenzene sulfonate. The preferred amount of sulfonate used is about 0.08 wt% to 0.8 wt%, more preferably 0.1 wt% to 0.5 wt%, most preferably 0.15 wt% to 0.40 wt%.

In these colored compositions, the preferred pigment is ultramarine blue, which is an inorganic silicate. Although the substance is inert to hypochlorite oxidation and does not catalyze the decomposition reaction of hypochlorite, it is insoluble and needs to be suspended in the hypochlorite solution. This suspension cannot be made by simply dispersing ultramarine blue particles in a hypochlorite solution because the pigment has a density of 2.35 and even very fine particles will settle. The viscosifying system used in the compositions of the present invention provides excellent suspension of the ultramarine blue pigment particles. Ultramarine is used in the composition of the present invention in an amount of about 0.01 wt% to 0.50 wt%, preferably about 0.05 wt%.

The molar ratio of tertiary amine oxide to alkali metal alkylbenzene sulfonate should be in the range of about 5:1 to about 11:1. Preferably, the molar ratio is 6:1-10:1, more preferably 7:1-9:1.

This composition provides higher viscosity to alkali metal hypochlorite bleaches while providing a commercially acceptable colored composition which is excellent in color stability. While not wishing to be bound by any particular theory, it is believed that the primary interaction is between the clay and the amine oxide in the composition. In the following preferred embodiments, the combination of clay, sodium chloride and sodium hydroxide solution produces an edge-to-face structural alignment of the clay particles. Some amine oxides achieve structural stabilization through ionic and steric interactions. Sulfonate and sarcosinate surfactants combine with the remaining amine oxides to form organic structures or micelles that enhance viscosity. A further theory is that these micelles interact with the clay structure, giving rise to the unique rheological properties of the composition.

The present invention provides commercially advantageous colored thickening systems which are thixotropic and which are particularly easy to dispense from spray containers. Cleaning products using this thickening system have a high enough rest viscosity to stabilize the inorganic pigment particles in suspension.

The present invention will be better understood by reference to the Examples, which are given by way of illustration only and not of limitation.

Example 1

A blue hand surface cleaner was prepared having the following components, all percentages are by weight. Components Bentonite (Gelwhite H) 1.00% Ultramarine 0.05% Sodium Chloride 1.00% Sodium Hydroxide 2.50% Tetradecyl Dimethylamine Oxide 5.60% Sodium Hypochlorite 2.50% Sodium Dodecyl Benzene Sulfonate 0.72% Lauroyl Insarcinol Sodium Acid 1.00% Fragrance 0.065% Deionized Water Balanced to 100%

Prepare this cleaning composition by dispersing Gelwhite H, a montmorillonite (Southern Clay Products), in water in the main container (1) using a homogenizer until the clay is fully hydrated, then under vigorous stirring Join Ultramarine. In another vessel (2), sodium chloride and 25% aqueous sodium hydroxide solution were dissolved in water. The contents of container (2) were added to container (1) with vigorous stirring. Add the remaining ingredients in the following order with agitation: Ammonyx MO, 30% solution in tetradecyldimethylamine oxide, Stepan Company; fragrance; 16.67% solution of sodium hypochlorite bleach; Biosoft D-40, 40% solution in ten Sodium dialkylbenzenesulfonate solution, Stepan Company; and Hamposyl L-30, a 30% solution of sodium lauroyl sarcosinate, W.R. Grace & Company.

Figure 1 shows the rheological profile of this preferred embodiment. It generalizes the shear stress as a function of time at four shear rates. Under constant shear conditions, the composition is rheological at both 1 and 10 sec ^-1 . Clearly thixotropic at 50sec ^-1 . Figure 2 captures the stress increase behavior at initial flow at the first shear rate of 1 sec ⁻¹ . Tests were performed with a Rheometrics Scientific RFSII rheometer, 50mm parallel plates, 0.9mm spacing, 316SS die, 25°C, 0.002-10gr-force rebalance.

Similar compositions without the clay and pigment components exhibit completely different rheological properties. See Figures 3 and 4. In examining the G' and G" coordinate plots, where G' is a measure of the elastic stress of a viscoelastic fluid and G" is a measure of the mechanical energy dissipated by a structural fluid during deformation, the properties of compositions with clays are comparable to highly structured fluids similarly, with apparent strain dependence. The properties are similar to those of a predominantly viscous fluid composition with no apparent strain dependence. This difference indicates a significant interaction between the clay component and the surfactant in the composition.

Example 2-5

According to the method of embodiment 1, prepare following composition: Component Example 2 % Example 3 % Example 4 % Example 5 % Montmorillonite (Gelwhite H) 1.00 1.00 1.00 1.00 ultramarine 0.05 0.05 0.05 0.05 Sodium chloride - 1.00 - 1.00 potassium chloride - - 1.27 - Sodium Hydroxide (25% aqueous solution) 2.50 2.50 - 2.500 Potassium hydroxide - - 0.88 - Tetradecyldimethylamine Oxide (30%) 5.60 4.20 5.60 5.60 Dodecyldimethylamine Oxide (30%) - 1.40 - - sodium hypochlorite 2.50 2.50 2.50 2.50 Sodium Lauroyl Sarcosinate (30%) 1.00 1.00 1.00 - Sodium Tetradecyl Sarcosinate (30%) - - - 1.10 Sodium dodecylbenzenesulfonate (40%) 0.72 0.72 0.72 0.72 spices 0.07 0.07 0.07 0.07 Deionized water to 100 to 100 to 100 to 100

comparative example

A cleaning composition containing ultramarine blue pigment, but no bentonite, was prepared and compared with the pigment settling properties of the composition of Example 1. A comparative composition was prepared using the method of Example 1. Both compositions were kept at rest at 40°C for 6 weeks. The following table shows the components of these two compositions and the associated rheological data.

surface Component Example 1 comparative example Bentonite 1.00% -- ultramarine 0.05% 0.025% Sodium chloride 1.00% 1.00% sodium hydroxide 2.50% 2.60% Tetradecyldimethylamine Oxide (30%) 5.60% 6.20% sodium hypochlorite 2.50% 2.50% Sodium dodecylbenzenesulfonate (40%) 0.72% 0.80% Sodium Lauroyl Sarcosinate (30) 1.00% 1.00% spices 0.065% 0.075% Deionized water to 100% to 100% viscosity 464 448 Pigment sedimentation no after 6 weeks Settles during week 3

These data show that, in contrast to the excellent suspension properties of Example 1, in the comparative example containing only half the amount of pigment, settling started within three weeks.

Claims (6)

1. A viscous colored aqueous hypochlorite composition comprising, by weight: (a) 0.5%-10% alkali metal hypochlorite; (b) 0.25%-1% bentonite; (c) 0.5%-2.5% of the following formula tertiary amine oxide Wherein, R ¹ is an alkyl group containing 10-16 carbon atoms, R ² and R ³ are respectively an alkyl group containing 1-3 carbon atoms; (d) 0.25%-0.2% alkali metal salt; (e) An effective amount is a pH stabilizer for pH 11 or higher; (f) 0.10%-0.75% of an alkali metal sarcosinate of the formula: Wherein, R ⁴ is straight chain C ₁₀ -C ₁₆ alkyl, M is lithium, sodium or potassium; (g) 0.08-0.80% alkali metal alkylbenzene sulfonate, wherein the alkyl is straight chain and contains 10 - 14 carbon atoms; and (h) 0.01% - 0.5% of an inorganic pigment, wherein the molar ratio of (c) to (g) is 5:1 - 11:1. 2. The hypochlorite composition of claim 1 wherein the (h) pigment is ultramarine blue. 3. The hypochlorite composition of claim 2, wherein (a) said alkali metal hypochlorite is sodium hypochlorite; (c) said amine oxide is lauryldimethylamine oxide, Tetraalkyldimethylamine oxides or mixtures thereof; (d) the alkali metal salt is sodium chloride; (e) the pH stabilizer is sodium hydroxide in an amount sufficient to make the pH 12-13.5; (f) the sarcosinate sodium lauroyl sarcosinate; (g) the alkali metal alkylbenzenesulfonate is sodium dodecylbenzenesulfonate. 4. The hypochlorite composition of claim 3 wherein (c) the amine oxide is dodecyldimethylamine oxide. 5. The hypochlorite composition of claim 4, comprising (by weight) (a) 1%-5% sodium hypochlorite; (b) 0.25%-1% bentonite; (c) 0.9%-1.8 % lauryl dimethylamine oxide; (d) 0.5%-1.5% sodium chloride; (f) 0.12%-0.60% sodium lauroyl sarcosinate; (g) 0.10-0.50% sodium dodecylbenzenesulfonate; and (h) about 0.05% ultramarine blue pigment, wherein the molar ratio of (c) to (g) is 6:1-10:1. 6. The hypochlorite composition of claim 5, comprising (by weight) (a) 1.5%-3.0% sodium hypochlorite; (c) 1.0%-1.5% dodecyldimethylamine oxide (f) 0.15%-0.30% sodium lauroyl sarcosinate; and (g) 0.15-0.40% sodium dodecylbenzenesulfonate; wherein, the molar ratio of (c) to (g) is 7 :1-9:1.

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