Patent Application
20170022454
1. The Field of the Invention
The present invention relates to drain cleaning formulations, particularly to liquid formulations for use in clearing a partially or fully blocked drain.
2. Description of Related Art
Much art has addressed the problem of developing a thickened cleaning composition, which may contain bleach and may have utility as a hard surface cleanser. The efficacy of such compositions is greatly improved by viscous formulations, increasing the residence time of the cleaner. Splashing during application and use is minimized, and consumer preference for a thick product is well documented. U.S. Pat. No. 4,375,421, issued to Rubin et al. describes a viscous, nonhypochlorite-containing composition containing at least five percent of amido and sulfobetaines, and water-soluble organic or inorganic salts such as sulfates and carbonates. Alkaryl sulfonates are specifically mentioned as possible surfactants for the composition. Rubin et al. is distinguishable, however, in that there is no disclosure of the composition being viscoelastic, and alkyl betaines are specifically excepted from those which are useful. Schilp, U.S. Pat. No. 4,337,163 shows a hypochlorite thickened with an amine oxide or a quaternary ammonium compound, and a saturated fatty acid soap, and mentions that a C8-18 alkyl betaine may be incorporated at levels about equal to the amine oxide (1.5 wt. %). Stoddart, U.S. Pat. No. 4,576,728 shows a thickened hypochlorite including 3- or 4-chlorobenzoic acid, 4-bromobenzic acid, 4-toluic acid and 3-nitrobenzoic acid in combination with an amine oxide, and mentions that a C8-18 alkyl betaine may be incorporated at levels about equal to the amine oxide (1.5 wt. %). Neither Schilp nor Stoddart disclose any thickening or rheological benefits by the optional inclusion of their betaines. DeSimone, U.S. Pat. No. 4,113,645 discloses a method for dispersing a perfume in hypochlorite using a quaternary ammonium compound. Bentham et al, U.S. Pat. No. 4,399,050, discloses hypochlorite thickened with certain carboxylated surfactants, amine oxides and quaternary ammonium compounds. Jeffrey et al, G B 1,466,560 shows bleach with a thickener comprising a sarcosinate or tauride surfactant, and a soap, quaternary ammonium compound, betaine, amine oxide, or alkanolamide. Farkas, U.S. Pat. No. 2,834,737 describes an unthickened hypochlorite bleach having about 0.05-1% of a C10-16 alkyl betaine as a foaming agent and to mask the hypochlorite odor. Hynam, U.S. Pat. No. 3,684,722 describes an alkali-metal hypochlorite which is thickened by a surface active agent, which may be a C8-18 alkyl betaine and a C8-18 soap. Hardy et al., EP 129,980 discloses hypochlorite, an amine oxide or betaine, and an organosilicon quaternary ammonium compound as a bacteriocide, and is limited to an ionic strength of below about 5.0 g moles/dm3. Gray, GB 1,548,379 describes a composition with thickened bleach incorporating a sucrose surfactant with a quaternary ammonium compound, an amine oxide, a betaine, an alkanolimide, or combinations thereof.
For various reasons, the prior art thickened hypochlorite compositions are not commercially viable. In many instances, thickening is insufficient to provide the desired residence time on non-horizontal surfaces. Adding components, and/or modifying characteristics of dissolved components often creates additional problems with the composition, such as syneresis, which require adding further components in an attempt to correct these problems. Polymer thickened hypochlorite bleaching compositions tend to be oxidized by the hypochlorite. Prior art thickened bleach products generally exhibit phase instability at elevated (above about 49 (degree) C.) and/or low (below about 2 (degree) C.) storage temperatures. Difficulties exist with colloidal thickening agents in that these tend to exhibit either false-bodied or thixotropic rheologies, which, at high viscosities, can result in a tendency to set up or harden. Other hypochlorite compositions of the prior art are thickened with surfactants and may exhibit hypochlorite stability problems. Surfactant thickening systems also are not cost effective when used at the levels necessary to obtain desired product viscosity values. European Patent Application 204,472 to Stoddart describes shear-thinning compositions, and seeks to avoid viscoelasticity in such shear-thinning compositions.
Drain cleaners of the art have been formulated with a variety of actives in an effort to remove the variety of materials which can cause clogging or restriction of drains. Such actives may include acids, bases, enzymes, solvents, reducing agents, oxidants and thioorganic compounds. Such compositions are exemplified by U.S. Pat. No. 4,080,305 issued to Holdt et al; U.S. Pat. No. 4,395,344 to Maddox; U.S. Pat. No. 4,587,032 to Rogers; U.S. Pat. No. 4,540,506 issued to Jacobson et al; U.S. Pat. No. 4,610,800 to Durham et al; and European Patent Applications 0,178,931 and 0,185,528, both to Swann et al. Generally, workers in this field have directed their efforts toward actives, or combinations of actives, which would have improved efficacy or speed when used on typically-encountered clog materials; or are safer to use. A problem with this approach, however, is that regardless of the effectiveness of the active, if the composition is not in contact with the clog for a sufficient period of time, the effectiveness of the active will be diminished. This is particularly true for partial clogs where the composition may simply flow by the clog down the drain without having sufficient contact with the clog to dissolve the materials causing the clog. That is why the surfactants, rheological properties and stability of the formulation are just as vital as the actives that help dissolve the clog material (e.g. hair, soap, etc.) because efficacy depends on the composition and the contact time.
Clogging of drains is a recurring and prevalent problem in a wide range of environments. Even with the availability of various drain clearing compositions, there continues to be a need for improved formulations.
In an embodiment, the present invention is directed to a drain cleaning composition comprising 4% to about 12% by weight of a hypochlorite oxidizing agent, 2.5% to about 10% by weight of a hydroxide, 1% to about 15% by weight of a surfactant, and water. In one embodiment, the pH of the composition is advantageously very high, being at least 13.
In another embodiment, the present invention is directed to a drain cleaning composition comprising 4% to about 12% by weight of a hypochlorite oxidizing agent, 2.5% to about 10% by weight of a hydroxide, a charged surfactant, an uncharged surfactant, and water. The composition is monophasic, and the ratio of the charged surfactant to uncharged surfactant is from 1:10 to about 1:50.
In another embodiment, the present invention is directed to a drain cleaning composition consisting essentially of 4% to about 12% by weight sodium hypochlorite, about 0.1% to about 10% by weight sodium hydroxide, a charged surfactant, an uncharged surfactant, and water. The composition is monophasic, and has a pH of at least 13.
Further features and advantages of the present invention will become apparent to those of ordinary skill in the art in view of the detailed description of preferred embodiments below.
To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the drawings located in the specification. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
I. Definitions
Before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified systems or process parameters that may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to limit the scope of the invention in any manner.
All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference.
The term “comprising” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.
The term “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention.
The term “consisting of” as used herein, excludes any element, step, or ingredient not specified in the claim.
It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a “surfactant” includes one, two or more surfactants.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
In the application, effective amounts are generally those amounts listed as the ranges or levels of ingredients in the descriptions, which follow hereto. Unless otherwise stated, amounts listed in percentages (“wt %'s”) are in wt % (based on 100 weight % active) of the particular material present in the referenced composition, any remaining percentage typically being water or an aqueous carrier sufficient to account for 100% of the composition, unless otherwise noted. For very low weight percentages, the term “ppm” corresponding to parts per million on a weight/weight basis may be used, noting that 1.0 wt % corresponds to 10,000 ppm.
II. Introduction
Hair is a major component of many drain obstructions, and in one aspect, the present invention is directed to an aqueous drain opening formulation that is particularly effective in hair dissolution so as to quickly unclog drains. The composition preferably has rheology characteristics that provide for easy and aesthetically pleasing dispensing by consumers. In addition, the particularly selected rheology characteristics provide for enhanced residence time of the composition to be in contact with the clog (e.g., particularly in the case of partial clogs where a portion of the drain is open). For example, when clearing a partial clog, there may be a tendency for the composition to be pulled away from the clog under influence of gravity through the open portion of the drain rather than remaining at the site of the clog so as to fully clear the obstruction. The ability of the present compositions to be better retained at the clog site (i.e., increased residence time) results in excellent efficacy.
In one aspect, the drain formulation may have a particular combination, concentration, and ratio of hypohalite and hydroxide ions (sodium hypochlorite and sodium hydroxide, respectively), which have been found by the inventors to provide enhanced hair dissolution properties. For example, it has been demonstrated that hair dissolving drain declogging formulations containing particularly selected levels of sodium hypochlorite and sodium hydroxide are especially effective in hair removal from drains. In particular the inventive drain formulation may be specially designed (e.g., due to its rheological characteristics) to coat and adhere to hair for a longer period of time as compared to existing formulations so as to allow the hypohalite and caustic active components to break down the hair protein and ultimately dissolve the clog.
In an embodiment, the drain formulation preferably includes an effective amount of one or more surfactants which enhances the efficacy of the actives in clog removal. Surprisingly, this can be achieved without increasing the dermal corrosivity characteristics of the drain formulation. To this end, the drain formulation preferably employs a surfactant blend that includes a low ratio of charged to uncharged surfactants to yield thick, monophasic systems having caustic hydroxide concentrations that in an embodiment may be greater than 2% hydroxide (e.g., 2.5 to about 10 weight percent sodium hydroxide). The specifically formulated surfactant blend (e.g., including both charged and uncharged surfactants) has surprisingly been found to result in a monophasic system, even at relatively high hydroxide and/or hypohalite concentrations, at which concentrations the composition would otherwise tend to be biphasic.
For example, the surfactant blend may include both charged and uncharged surfactants, where the ratio of charged surfactant to uncharged surfactant is 1:10 or 0richer with respect to the uncharged surfactant (e.g., 1:12, 1:15, 1:20, 1:30, etc.). For example, the ratio of charged surfactant to uncharged surfactant may range from 1:10 to about 1:50, or 1:10 to about 1:30. The inventors have found that where the ratio becomes more charged surfactant rich than 1:10 (e.g., a ratio of 1:9), the system may no longer be monophasic, but separates into two phases. It is advantageous to be able to provide a monophasic system, while also providing relatively high hypohalite and relatively high hydroxide concentrations.
In order to provide excellent coating characteristics to a clog during use, the drain formulation preferably has a relatively high zero-shear viscosity. For example, the zero-shear viscosity may be at least 1000 cP, at least about 3000 cP, or from about 3000 cP to about 9000 cP (e.g., all zero shear viscosity values may be at 25° C.). Relaxation times Tt of the composition may be relatively low as compared to other drain clearing formulations, e.g., less than 0.1 s, or less than 0.05 s. Angular relaxation time values (measured in s) may be converted to relaxation time values measured in seconds/cycle (Tau) by multiplying by 2π. Tt=[Tau/(2π)]=/<0.1 S (preferably, =/<0.05 S). 2π Tt=Tau, as previously defined in U.S. Pat. No. 5, 389,157 to Smith et al., which is herein incorporated by reference in its entirety.
Because of the high caustic hydroxide concentration, the drain formulation may have a pH that is correspondingly higher than typical existing drain clearing formulations. For example, the pH may be at least 13, or greater than 13.
The described rheology characteristics ensure thick and viscous flow behavior at the shear rates associated with flowing down a surface (e.g., along the interior of a vertical pipe) or through an obstruction under force of gravity. Systems with a relatively high relaxation time become elastic more readily under flow and thus are less effective at adhering to surfaces, leading to reduced contact time as compared to the present formulations. The drain formulation's relatively low relaxation time also ensures a smooth appearance as the drain cleaner is poured, which is visually pleasing to consumers. In other words, not only does the composition exhibit thick, viscous characteristics at low shear rates (e.g., exhibiting a critical shear rate of at least 1/sec, or at least 10/sec, or at least 15/sec, or at least 30/sec, etc.), but the appearance and consistency of the composition (e.g., during pouring) is smooth, rather than including undesirable blobs or globs of material that may tend to coalesce together.
The inventive formulations are characterized by a thickening system that is both stable in the presence of hypochlorite bleach and accommodates a relatively high concentration of actives ions. Existing high viscosity, thickened drain cleaners have lower ion concentrations and use bleach stable surfactant blends that would lead to biphasic systems under the high actives load conditions exhibited by the inventive formulations. Surfactant compositions appropriate for thickening the high ion concentrations of the inventive formulations have a low charged to uncharged ratio as described above, such that the ratio of charged surfactant to uncharged surfactant is less than some critical level (e.g., 1:10). The actual critical lower limit of the ratio of charged to uncharged surfactants may depend on various factors, including but not limited to, the presence and concentration of other ions, surfactant chain length, etc. Within the working examples, the inventors have observed that at a ratio of 1 part charged surfactant to 9 parts uncharged surfactant, and with the above described relatively high hydroxide and hypochlorite ion concentrations, the system becomes biphasic. At a ratio that is slightly richer in uncharged surfactant (e.g., 1:10), the system is monophasic.
In an embodiment, the drain cleaning formulation may be opacified to exhibit an enhanced, stable phase appearance. For example, the composition may include an opacifier such as a white latex suspension comprising styrene-acrylate copolymers. The opaque formulation provides gel differentiation versus conventional drain cleaners that are clear.
As described above, it has also been found that the particularly described surfactant blends (e.g., blends of charged and uncharged surfactant) can reduce dermal corrosivity characteristics (e.g., as measured by a Corrositex™ test), while at the same time actually increasing the effectiveness of the composition in clearing a clog. Thus, the compositions can exhibit excellent drain clearing characteristics equal to or better than existing drain cleaners, while also exhibiting dermal corrosivity characteristics (relative to safety considerations for the consumer) that are at least comparable if not better than existing drain cleaners, even while including substantially higher concentrations of hypochlorite and hydroxide within the formulations. In other words, the surfactants provide the added benefit of producing a protective boost or enhancement vis-a-vis the damaging corrosivity characteristics (as measured in terms of the time a substance takes to penetrate a membrane). Ordinarily, compositions with increasing levels of actives such as sodium hydroxide and sodium hypochlorite exhibit higher dermal corrosiveness. While the surfactants enhance the efficacy of the actives in dissolving hair, there is little or no corresponding increase in dermal corrosivity.
III. Exemplary Components of the Aqueous Drain Formulations
A. Oxidizing Agents
The oxidizing agent or oxidant preferably includes a hypohalite (e.g., hypochlorite)-producing species, for example, halogen bleaches selected from the group consisting of the alkali metal and alkaline earth salts of hypohalites. More broadly, a bleach source may be selected from various hypohalite-producing species, for example, halogen bleaches selected from the group consisting of the alkali metal and alkaline earth salts of hypohalite, haloamines, haloimines, haloimides and haloamides. All of these are believed to produce hypohalous bleaching species in situ. Hypochlorite and compounds producing hypochlorite in aqueous solution are preferred, although hypobromite may also be suitable. Representative hypochlorite-producing compounds include sodium, potassium, lithium and calcium hypochlorites, chlorinated trisodium phosphate dodecahydrate, potassium and sodium dicholoroisocyanurate and trichlorocyanuric acid. Organic bleach sources suitable for use may include heterocyclic N-bromo and N-chloro imides such as trichlorocyanuric and tribromo-cyanuric acid, dibromo and dichlorocyanuric acid, and potassium and sodium salts thereof, N-brominated and N-chlorinated succinimide, malonimide, phthalimide and naphthalimide. Hydantoins, such as dibromo and dichloro dimethyl-hydantoin, chlorobromodimethyl hydantoin, N-chlorosulfamide (haloamide) and chloramine (haloamine) may also be suitable. Combinations of such components may also be employed.
A particularly preferred hypochlorite-producing compound is sodium hypochlorite. The hypohalite (e.g., sodium hypochlorite) may be present in an amount ranging from about 0.1 to about 15 weight percent, about 4 weight percent to about 12 weight percent, or from about 5 weight percent to about 7 weight percent of the aqueous drain formulation.
B. Hydroxide Stabilizing Agents
A caustic bleach stable hydroxide is included. The hydroxide serves to provide a very high pH, acts to help in break up of the clog (e.g., hair dissolution), and substantially enhances the stability of the hypohalite (e.g., hypochlorite) producing oxidant. Exemplary stabilizers include alkali metals of hydroxide, such as sodium, lithium, potassium hydroxide, or combinations thereof. Sodium hydroxide is a particularly preferred example. The hydroxide may comprise from 0.1 to 15, 0.1 to 10, from 2.5 to 10, or from 7 to 8 percent of the aqueous drain formulation by weight. The aqueous drain formulation preferably has a pH of at least 13, or above 13, providing both hair dissolution efficacy and hypochlorite stability. The particularly preferred ranges of sodium hypochlorite (e.g., 4 to 12 weight percent, more particularly 5 to 7 weight percent) and sodium hydroxide (e.g., 2.5 to 10 weight percent, more particularly 7 to 8 weight percent) have been found by the inventors to provide enhanced hair dissolution as compared to lower weight fractions employed previously.
C. Surfactants
Surfactants aid in providing thickening, providing other desired rheological characteristics, and in providing improved phase stability (e.g., the ability to maintain a monophasic system, even with high hydroxide and hypohalite ion loading). Surfactants may be oxidant stable anionic surfactants, nonionic surfactants, zwitterionic surfactants, amphoteric surfactants, cationic surfactants, ampholytic surfactants, or mixtures thereof. Preferably, a surfactant blend having a low ratio of charged to uncharged surfactants is used. The total amount of surfactant typically ranges from 1 to 15, and preferably from 3 to 10 weight percent of the aqueous drain formulation. Preferred uncharged surfactants include amine oxide surfactants, e.g., alkyl amine oxide surfactants such as lauryl dimethylamine oxide and myristamine oxide. Such alkyl amine oxide surfactants may include chain lengths from 6 to 18 carbons (e.g., lauryl designates a C12 chain, myristyl designates a C14 chain).
A preferred charged surfactant is a fatty acid (e.g., coconut fatty acid), which is nonionic at neutral pH, but becomes charged (e.g., anionic) under the high pH conditions associated with the composition. Coconut fatty acid may refer to a mixture of alkyl fatty acids having carbon chain lengths from 6 to 18, with the vast majority of the components being C12 and C14. Other suitable charged surfactants include but are not limited to sodium lauryl sulfate (SLS), linear alkyl benzene sulfonate (LABS) and any other suitable sulfate or sulfonate surfactants and any combinations or mixtures thereof. Surfactant blends with particularly preferred low ratios of charged to uncharged surfactants yield thick, monophasic systems with relatively high caustic hydroxide levels (greater than about 2% NaOH). Preferred surfactant ratios also have been shown to reduce dermal corrosivity characteristics (as measured by the time a substance takes to penetrate the test membrane).
Other nonionic, anionic, cationic, ampholytic, amphoteric and zwitterionic surfactants and mixtures thereof may be suitable for use. A typical listing of anionic, ampholytic, and zwitterionic classes, and species of these surfactants, is given in U.S. Pat. No. 3,929,678 to Laughlin and Heuring. A list of suitable cationic surfactants is given in U.S. Pat. No. 4,259,217 to Murphy. Each of the above patents is incorporated by reference in its entirety.
D. Opacifier
The drain formulation may be opaque, through inclusion of an opacifier. A preferred opacifier is white latex suspension which imparts an enhanced, stable phase appearance to the formulation. These visual characteristics, together with the thick, viscous, but smooth flow characteristics (e.g., the absence of the formation of coalescent blobs or globs), provide an aesthetically desirable delivery and flow appearance. The opacifier is preferably stable at the above described elevated hypochlorite and hydroxide concentrations. Suitable white latex suspensions are composed of styrene-acrylate copolymers. The opacifier typically comprises from 0.05% to 1.0% by weight of the aqueous drain formulation. Other opacifiers may also be suitable for use.
E. Additional Adjuvants
The drain formulation can comprise coloring agents including dyes and pigments. Fragrances (e.g., bleach stable) and corrosion inhibitors can also be employed. Alkali metal silicates (e.g., sodium silicate) are a preferred class of corrosion inhibitors for minimizing corrosion within steel pipes.
F. Water
The balance of the aqueous drain formulation may comprise water. For example, the water content may typically range from 50 to 90 percent of the formulation by weight. Soft or distilled water is preferred to minimize effects of trace ions, resulting in a stable, viscous, optionally opacified drain clearing formulation.
In use, the aqueous drain formulation may be dispensed from a bottle container into a fully or partially clogged drain. The formulation is allowed to react with the clogging material, often including hair, for 30 minutes or longer. Typically, about 75 to 250 mL of the drain formulation may be used. Thereafter, the drain may be flushed with water to remove any remaining drain formulation and clog remnants. The process can be repeated as necessary.
IV. Exemplary Formulations and Test Results
Table 1 sets forth exemplary preferred ranges for components of several drain cleaning formulations that were prepared according to the working examples of the present invention.
The zero-shear viscosities of several exemplary drain formulations were measured and the data is set forth in Tables 2-6.
A. Selected Levels of Sodium Hypochlorite and Sodium Hydroxide
Correlated to Enhanced Hair Dissolution
Formulations containing 0-20% NaOH and 0-14% NaOCl were tested for their ability to dissolve hair (i.e., weight percent hair loss).
Highly Viscous Formulations for Enhanced Active Delivery System in Drain (with >2% NaOH)
In Example 7A, a formulation with 15% NaOH, 5% NaOCl, and a surfactant blend including 0.6% coconut fatty acid (CFA) and 5.4% Lauryl Dimethylamine Oxide (LO) formed a biphasic system in the presence of the high hydroxide and hypochlorite ion concentrations. The ratio of charged surfactant (i.e., the CFA) to uncharged surfactant (i.e., the LO) in Example 7A was 1:9. A similar formulation (Example 7B) containing 0.3% CFA and 5.7% LO was made monophasic due to the decrease in the ratio of charged surfactant to uncharged surfactant. The ratio of charged surfactant (i.e., the CFA) to uncharged surfactant (i.e., the LO) in Example 7B was 1:19. The balance of each formulation was water.
A similar transition from biphasic to monophasic with decreasing ionic ratio is observed with other anionic surfactants, as shown in Table 8 for SLS, and in Table 9 for LABS.
Further adjustments to achieve the desired viscosity can be made by changing chain length of one or more of the surfactants, or adjusting the total surfactant concentration. Table 10 illustrates inventive compositions with zero-shear viscosities in preferred ranges of at least 1000 cP, or from about 3000 cP to 9000 cP. The examples of Table 10 include myristamine oxide, also known as myristyl dimethylamine oxide (MO) as the uncharged surfactant.
In general, the higher the caustic concentration, the lower the proportion of charged surfactant required in order for the drain formulation to remain monophasic. In Tables 7-9 above, the phase behavior of these exemplary formulations shows that at a 1:9 ratio of charged: uncharged surfactant the compositions are cloudy and biphasic at 25° C. In Tables 7-9 above, the phase behavior of these exemplary formulations shows that at 1:19 (and 1:39 for Tables 8-9) ratios of charged: uncharged surfactant the compositions are clear and monophasic at 25° C. The similar phase behavior results are shown in
For the contour plot of
The contour plot illustrates that in order to stay monophasic (i.e. below the line 16), increasing levels of caustic have to be compensated for by decreasing delta, the proportion of charged surfactant (e.g., CFA, SLS, LABS, etc.). For example, CFA is nonionic at neutral pH, but becomes anionic at the high pH values associated with the present compositions. Delta is the proportion of charged surfactant (e.g., anionic or cationic surfactants with charged head groups at formulation conditions). Preferred ranges for delta (e.g., corresponding to proportion of surfactant that is charged) are from 0.01 to 0.1 0.05 to 0.099, 0.02 to 0.09, 0.03 to 0.08, or 0.01 to 0.07
The inventive formulations have a high zero-shear viscosity and relatively high critical shear rate. The viscosity vs. shear rate of 7 different drain cleaning formulations were measured and the results are shown in
Thickening systems commonly used for this type of active (e.g., bleach) are oxidant stable surfactants that form a network of entangled micelles, giving a viscoelastic rheology. Such systems are characterized by a region of constant viscosity at low shear rates, called the zero shear viscosity, and a critical shear rate, which is the shear rate at which the elongated micelles begin to align and flow more easily in shear flow, leading to a decrease in viscosity, as readily seen in
Preferred values of zero-shear viscosity are 1000 cP or higher, with a critical shear rate of at least 1/sec. (e.g., at least about 5/sec, or at least about 10/sec).
The rheology of the drain cleaning composition was also measured with a Stresstech rheometer at 25° C. in the oscillatory mode and in the viscometry mode, using concentric cylinder geometry. A frequency sweep with a Stresstech rheometer produced oscillation data which shows the elastic and viscous moduli, G′ and G″ respectively, and the (complex) Viscosity, as a function of frequency.
Values for Tt, Go, and η° for the testing shown in Table 13 were 0.040243 s, 95.33521 Pa, and 3783.635 cP, respectively.
Values for Tt, Go, and η° for the testing shown in Table 14 were 0.034184 s, 123.0668 Pa, and 4083.889 cP, respectively.
B. Decreased Dermal Corrosivity as a Result of Increased Surfactant Concentration
One important negative characteristic of existing drain cleaners is their high degree of corrosivity to skin, which determines their packing group and transportation requirements for regulatory purposes. The Corrositex™ test method is an in vitro test that determines chemical corrosivity of products in lieu of animal skin testing. The test gives reproducible and reliable results, which are accepted by many federal agencies. The time a substance takes to penetrate the Corrositex™ membrane determines its degree of corrosivity. It was demonstrated that the increased surfactant concentrations (which boost the efficacy of the actives in hair clog removal performance as described herein) did not lead to an increase in corrosivity. In fact, surprisingly, inclusion of the described surfactant blends may provide a protective effect, leading to decreased dermal corrosivity. This is observed in the increased Corrositex™ penetration time with increased surfactant concentrations as shown in
Without departing from the spirit and scope of this invention, one of ordinary skill can make various changes and modifications to the invention to adapt it to various usages and conditions. As such, these changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/698,988, filed on Sep. 10, 2012, and U.S. patent application Ser. No. 13/950,140, filed on Jul. 24, 2013, the disclosures of which are both incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61698988 | Sep 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13950140 | Jul 2013 | US |
| Child | 15289490 | US |
