FIELD OF THE INVENTION
This application relates to rinse-off cleansing compositions with surfactant, perfume, solvent, and water; and methods relating thereto.
BACKGROUND OF THE INVENTION
Cleansing is an activity that has been done for thousands of years. Early cleansers were based on either soap chemistry or simple mechanical action in order to remove dirt from the skin, as well as endogenous soils such as sweat, sebum and body odors. Smelling clean is an important benefit but early cleansers did not provide perfume to the skin during cleansing as it would have been wasteful for a very expensive ingredient, the perfume. Instead, perfume was applied after cleansing. As skin cleansing compositions have become more complex, providing scent during cleansing and residual scent on the skin after cleansing are expected by users of modern skin cleansers. Chinese Patent Application CN103893060 A
is related to a leave-in conditioner and a preparation method thereof. The conditioner comprises the following components in a certain mass ratio: 20-30 parts by mass of sodium lauryl sulfate, 15-23 parts by mass of a betaine, 2-4 parts by mass of a natural pigment, 5-10 parts by mass of olive oil, 5-9 parts by mass of aloe vera, 3-6 parts by mass of plant essential oil, 7-10 parts by mass of glycerin, 6-11 parts by mass of propylene glycol, 3-4 parts by mass of vitamin C, 2-4 parts by mass of octyl-methoxycinnamic acid, and 100-150 parts by mass of water. US Patent US 6,362,155 B1
refers to an alleged improvement in a microemulsion composition which has superior cling to a vertical surface and is especially effective in the removal of oily and greasy soil and are mild to the skin, the composition containing an anionic detergent, a thickener, a hydrocarbon ingredient, a cosurfactant and water, wherein the composition has a pH of at least 12.5. As such, improved cleansing compositions which can provide scent during cleansing and/or residual scent on the skin are desired.
SUMMARY OF THE INVENTION
A rinse-off cleansing composition, comprising: a) from 20% to 34%, by weight of the composition, of surfactant, wherein the surfactant comprises a first branched anionic surfactant and a cosurfactant; b) from 4% to 30%, by weight of the composition, of a perfume, wherein the weight percent of perfume is from 10% to 90%, by weight of the surfactant; c) from 3% to 20%, by weight of the composition, of a solvent, wherein at least 3% of the solvent, by weight of the composition, comprises a hydric solvent, wherein the composition has from 4% to 16%, by weight of the composition, of the hydric solvent, wherein the hydric solvent comprises dipropylene glycol, diethylene glycol, dibutylene glycol, hexylene glycol, butylene glycol, pentylene glycol, heptylene glycol, propylene glycol, a polyethylene glycol having a weight average molecular weight below 500, or a combination thereof; preferably dipropylene glycol, and wherein the weight percent of the hydric solvent is from 8% to 60%, by weight of the surfactant; and d) from 10% to 73%, by weight of the composition, of water; wherein the rinse-off cleansing composition is not a ringing gel, and wherein the composition is a microemulsion or contains a microemulsion phase.
Use of a hydric solvent to enhance perfume deposition from a rinse-off cleansing composition, wherein the composition comprises: a) from 15% to 20%, by weight of the composition, of a first surfactant comprising a branched anionic surfactant; b) from 4% to 10% of a zwitterionic cosurfactant; c) from 4% to 10%, by weight of the composition, of a perfume; d) from 4% to 10%, by weight of the composition, of a hydric solvent, wherein the hydric solvent comprises dipropylene glycol, diethylene glycol, dibutylene glycol, hexylene glycol, butylene glycol, pentylene glycol, heptylene glycol, propylene glycol, a polyethylene glycol having a weight average molecular weight below 500, or a combination thereof; wherein the rinse-off cleansing composition is not a ringing gel, and wherein the composition is a microemulsion or contains a microemulsion phase.
These and other compositions will be more fully understood in light of the detailed description below.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the following terms shall have the meaning specified thereafter:
"Cleansing composition" refers to compositions intended for topical application to the skin or hair for cleansing.
"Concentrate/concentrated" as used herein with respect to a cleansing composition refers to a composition where the weight percentage of surfactant relative to the total composition is greater than 15%.
"Free of' refers to no detectable amount of the stated ingredient or thing.
"Gel" refers to a material or composition that does not flow under its own weight and has a G' greater than 25 Pa at 10 Hz in an oscillatory rheology test.
"Hydrotrope" refers to a charged, amphiphilic solubility modifier. Hydrotropes are generally charged olefins especially an olefin sulfonate such as an aromatic sulfonate.
"In-vitro Bloom" refers to the amount of perfume experienced at a 3:1 by weight water to composition dilution versus the amount of perfume in the headspace prior to dilution and can be measured in accordance with Perfumed Headspace Abundance During Dilution Method set out below.
"Micelle" as used herein refers to a structure comprising individual surfactant molecules aggregated to form a hydrophobic core region with externally facing polar head groups in equilibrium with surfactant monomers in a polar phase, having a characteristic dimension that is a single digit multiple of the surfactant length, i.e., generally less than 10 nm in diameter.
"Microemulsion" as used herein refers to a thermodynamically stable isotropic mixture of oil, surfactant, and water comprising an interior hydrophobic core, having a size greater than 10 nm diameter.
"Perfume" refers to a mixture of volatile organic oils having a pleasant aroma wherein the perfume components have individual molecular weights between 75 and 400 Daltons.
"Relative Bloom" refers to perfume in the headspace over a composition during use for a perfumed cleansing composition relative to concentration for a conventional, hydric solvent free, control micelle composition having 10 wt% starting surfactant and 1 wt% starting perfume when the same perfume is used in the composition and the micelle composition.
"Rinse-off' means the intended product usage includes application to skin and/or hair followed by rinsing and/or wiping the product from the skin and/or hair within a few seconds to minutes of the application step. The product is generally applied and rinsed in the same usage event, for example, a shower.
"Room temperature" refers to a temperature of 25°C.
"Solvent" refers to species or mixture of species present in a molecular solution in the greatest molar concentration acting in a way to dissolve other species, the latter species generally being larger molecules. A "hydric solvent" is a water miscible solvent.
"Single Phase" when used herein with respect to inventive cleansing compositions refers to homogeneity when measured at the designated temperature in accordance with the Ultracentrifuge Test.
"Stable" when used herein with respect to the inventive cleansing compositions refers to visual stability when measured in accordance with the Stability Test herein.
"Substantially free of" refers to 2% or less, 1% or less, or 0.1% or less of a stated ingredient.
"Surfactant" as used herein refers to amphiphilic molecules which can aggregate to form micelles and other surfactant structures, which are soluble in an aqueous phase and contribute to foaming during a cleansing event, i.e., stabilizing an air interface.
II. Cleansing Compositions
Modern consumers of cleansing compositions expect the composition to provide scent both during use and to have residual scent on the skin after use, making perfume an important component of cleansing compositions. Perfume is also an important component of many skin cleansers to mask the base odor of cleansing ingredients, which can be unpleasant.
Perfume is hydrophobic, whereas skin cleansers generally have an aqueous, continuous phase which provides essentially no ability to carry perfume. It is desirable to provide perfume in a soluble form in a liquid skin cleanser, since insoluble phases of any kind can lead to instability problems in the composition. Perfume is therefore generally solubilized within the surfactant component of cleansers, such as micelles, lamellar structures, vesicles and the like. Surfactant structures of all kinds contain hydrophobic regions due to the aggregation of surfactant tails, which are able to solubilize significant quantities of perfume oil. Perfume generally exists within the surfactant tails as a molecular solution due to the interaction of the perfume with the surfactant tails, not as a colloidal structure such as an emulsion droplet, which is not thermodynamically stable.
A problem exists in providing perfume scent during use and residual scent to the skin from skin cleansers. Well known physical laws govern the relationship between perfume in the air in equilibrium with perfume solubilized in a micelle or other environment. This relationship is defined by the mole fraction of perfume in the soluble environment, generally the micelle. Micelles are common features of skin cleansers since even non-micellar surfactant generally become micelles during the dilution experienced while cleansing.
Since the perfume concentration in a skin cleanser is generally only 25% or less on a molar basis in the surfactant micelle, the vapor pressure of each perfume molecule can be reduced by 75% or even more, due to its solubilization in the micelle. The desire to deliver perfume to the skin suffers from a similar fate during cleansing. Perfume molecules can diffuse, or partition into the skin during cleansing. The driving force to do so is the thermodynamic activity coefficient gradient for the perfume molecules. While a pure perfume applied to the skin, having an activity coefficient of 1, can partition quickly into skin, perfume located in a surfactant micelle proximal to the skin suffers from the activity coefficient reduction (75% or more) due to micellar solubilization. Therefore most perfume in cleansing compositions (between 50-90%) generally is washed away during rinsing before a significant amount can partition into the skin or bloom into the headspace. The result is the skin retains no or very little scent and only for a short duration after a typical cleansing event. Thus, delivery of perfume to the air and to the skin during cleansing is inefficient and therefore expensive.
Overcoming these technical constraints in order to increase initial perfume perception in a neat composition, perfume delivery to the air during cleansing, and to the skin is not simply a matter of adjusting formula components at increased cost. Natural limits exist related to factors such as solubility. For example, increasing perfume in a composition is not only impractical from a cost standpoint, perfume being quite expensive, but is also infeasible considering the abundance of perfume can quickly become insoluble in the surfactant composition, leading to instability. Formulating a perfume to contain more high vapor pressure components to enhance bloom may be useful, but does not overcome the innate vapor pressure reduction of perfume due to solubilization in the micelle, in addition to other restrictions to the scent character that would result. Benefits of these approaches are limited.
Various means to overcome this problem have been suggested. Perfume microcapsules have been developed to encapsulate perfume and protect it from contact with surfactant. However, only a limited number of perfume molecules are stable in perfume microcapsules; and the perfume microcapsule itself must then be delivered to the skin and, later, mechanically crushed by the consumer in order to release the perfume. Most perfume microcapsules are themselves washed down the drain during cleansing, affording little benefit.
Additionally, cleansing compositions have been formulated as micelles. Surfactants have a critical micelle concentration, or CMC, at which they aggregate. Below the CMC surfactant exists as monomers in solution. It has been suggested that dilution to below the CMC can release perfume to increase bloom. The problem with this approach is the CMC is very low, often 100 ppm for cleansing surfactant mixtures (i.e., 0.01 wt.%, a dilution of more than 500-fold from an original composition). Thus, the CMC occurs at concentrations not relevant to cleansing nor rinsing the body. During rinsing, the CMC is reached only at the very end of cleansing, by which time nearly all the cleansing components have already been washed down the drain in the form of micelles, carrying the perfume with them. Relevant dilutions during cleansing are less than 10-fold, especially less than 5-fold, during which time there is extensive exposure of the wash composition to the body and to the air in the shower, affording both time and opportunity for perfume to bloom and partition to the skin, if it can be removed from the environment of the micelle.
A constraint in overcoming these problems relates to the rheology profile of the composition. Liquid skin cleansing compositions generally require dosing from a package onto a hand, a cleansing implement, or the skin itself without running off. Further, compositions should spread easily across the body to effect thorough cleansing. Preferred means to provide an acceptable rheology involve the use of surfactants to form elongated micelles or lamellar structures without the use of other rheology control agents, which can be wasteful and costly. Control of rheology using surfactants can provide important restrictions which limit the ability to modify surfactant mixtures to provide other benefits, such as perfume benefits. Often, polymeric or associative thickening agents can be used to control rheology, but these can create new restrictions or constraints by interacting with micelles. Overcoming the problems related to perfume benefits in cleansing compositions while maintaining an acceptable rheology profile for dispensing is therefore a highly constrained problem and difficult to overcome. Control of rheology in concentrated compositions having only 2x concentration to 3x concentration (i.e., 15 wt% to 35 wt% surfactant by weight of the composition) can be particularly challenging in compositions which utilize solvents to enhance perfume delivery, because the relatively low levels of surfactant minimize rheology contribution while at the same time the solvents also reduce rheology attributes such as viscosity and G' (elasticity).
Surprisingly, inventors have discovered skin cleansing compositions can deliver enhanced initial perfume perception, perfume bloom during cleansing, and perfume retention on the skin for many hours after cleansing. Without wishing to be limited by theory, the enhanced perfume benefits are believed to result at least in part when at least a portion of the perfume in a composition exists in the physical form of a perfume microemulsion. In some cases, the microemulsion may be in equilibrium with other phases such as micelles or a lamellar phase. In some cases, the microemulsion can spontaneously form upon addition of water, i.e., during cleansing or rinsing. In the microemulsion form, it is believed most perfume is in the central core region and is not proximal to surfactant hydrocarbon, therefore it is not in a solvent-solute relationship which can reduce perfume activity coefficient. The result is bloom and/or relative bloom is significantly enhanced, sometimes doubled or even tripled or more; and scent of perfume over the skin after wash, can be enhanced by a similar magnitude.
To make a perfume microemulsion, sufficiency of perfume, which is the oil component for making a perfume core; the right level and mixture of surfactant; and a hydric solvent able to interact in a manner to make the microemulsion are believed to be contributing factors. The hydric solvent has multiple effects like, reducing the dielectric of the water phase, acting as a solvent for the surfactant head groups, reducing interfacial tension between the aqueous phase and hydrocarbon, and interacting with the perfume in the core. Hydric solvents can be chameleonic in nature, able to provide miscibility with hydrophobic perfume oil and water external to the microemulsion phase. During use of the body cleansing composition, as the composition is diluted, hydric solvent can be reduced in concentration in a perfume microemulsion core because of the abundance of water added during washing and rinsing, providing a further benefit to increase perfume activity coefficient by increasing perfume molar concentration in the core. Thus, a sufficient amount of particular kinds of hydric solvents can be used to form a microemulsion phase which can increase perfume activity during use.
Certain microemulsions may be in equilibrium with other phases, such as micelles or a lamellar phase, either in the composition or during dilution of the composition during use. There may be advantages for both the microemulsion and micelle phases to coexist, since micelles may provide superior lather and cleaning properties at the same time the microemulsion may deliver enhanced perfume benefits. Certain analytical measures, such as dynamic light scattering and optical light transmission, can be used as guides, when evaluating microemulsion phases. Additionally, perfume analysis in the headspace is directly relatable to the perfume solvent environment in a composition or a diluted composition, so that gas chromatography - mass spectrometry (GCMS) headspace measures are an indicator of the perfume environment, i.e., the microemulsion phase and the perfume relationship to solvent molecules therein. Well established physical laws govern the relationship between concentration of molecules in the headspace, and the solvent environment of the molecules in solution, e.g., Raoult's Law. Likewise, headspace measurements over the skin after washing are similarly useful, since perfume partitioning into the skin is enhanced by perfume activity coefficient, as previously discussed.
When the microemulsion phase is present, increased bloom and/or relative bloom can be demonstrated by measuring the relative abundance of perfume in the headspace over the composition or comparative composition using the Perfume Headspace Abundance During Dilution Method (PHADD), which utilizes solid phase microextraction GCMS (SPME-GCMS) to collect and evaluate perfume molecules (PRM) in the headspace over a neat composition and through stepwise aqueous dilutions. Results can be compared to a control micelle composition using the same perfume. When inventive compositions form a microemulsion phase, headspace perfume concentration can more than double compared to control, sometimes providing a 3-fold or greater headspace perfume concentration compared to control. In addition, evaluation among untrained and undirected consumers confirms extraordinary noticeability of the bloom benefit.
Increased perfume retention on the skin after cleansing can be demonstrated by measuring the relative abundance of perfume in the headspace over the skin using the Perfumed Skin Headspace Abundance Method (PSHAM), which utilizes a collector in a glass dome-shaped chamber over the skin to collect perfume, followed by heat desorption and evaluation of PRM by GCMS. Relative to control micelle compositions at the same perfume dose, inventive compositions can provide more than double the scent over the skin compared to control, sometimes providing a 3-fold or greater perfume retention on skin compared to control. Evaluation among untrained and undirected consumers confirmed extraordinary noticeability of the skin retention benefit.
Dynamic Light Scattering is a useful means to detect structures in the size range of microemulsion droplets, and micelles, but the results can be difficult to interpret when more than one structure may be present, such as micelles and a microemulsion both. A bimodal scattering intensity distribution may be present in inventive compositions, suggesting micelles having a diameter generally below 10 nm in equilibrium with larger structures, which are generally greater than 20 nm which are the perfume microemulsion droplets.
A microemulsion phase generally has a low viscosity and is a Newtonian fluid. Cleansing fluids with these viscosity characteristics are generally useful when dispensed from a package which controls the dose or spreads it onto the target surface, such as a pump foamer or a spray. To fit with current consumer habits during body cleansing, a cleansing composition can be in the form of a gel having a structure defined by an elastic modulus, G', a viscous modulus, G", a viscosity, and a shear thinning viscosity ratio as measured by the test methods below. A microemulsion composition can be concentrated to create a gel, wherein the gel provides a suitable rheology to easily dispense the composition from a package. The gel may comprise a lamellar phase, and may or may not have a high concentration of perfume in its headspace prior to being diluted, relative to a micelle composition. In some cases, when the gel has a high perfume concentration in its headspace, it is believed to be in equilibrium with a microemulsion phase, since the gel can evince a characteristic lamellar x-ray diffraction pattern. In other cases, the gel can have a high perfume concentration in the headspace only after dilution water is introduced.
The composition may be concentrated in order to create desirable rheology characteristics, i.e., a gel. Some compositions may be concentrated at least 3-fold relative to conventional body wash, which generally has 10 wt% surfactant. When the amount of surfactant is greater than 15 wt% of the composition, the surfactant can be considered to be concentrated and the composition can be considered to be a concentrate. Generally, a composition having 20 wt% surfactant can be considered a 2-fold concentrate, a composition having 30 wt% surfactant a 3-fold concentrate, and so on.
In certain cases, increasing concentration may be preferable because a gel can be created which has both desirable rheology characteristics useful for dispensing, in addition to a sufficiency of hydric solvent to form the microemulsion phase either as a component of the gel or during dilution of the composition. Some hydric solvents can significantly reduce the viscosity and/or G' of the gel, therefore concentration can be a useful means to increase the amount of hydric solvent that can be tolerated within a composition.
Additionally, organic solvents are useful to help form a microemulsion phase. Some organic solvents are miscible in water, at least partially miscible in perfume oil, and can interact with surfactant polar head groups to reduce structure and generally reduce viscosity as a result. The microemulsion phase requires very low interfacial tension. Perfume can be essentially relegated to the core of a water continuous microemulsion phase and therefore has a high activity coefficient, which can be effected by using a hydric solvent having water, perfume oil, and surfactant miscibility to reduce interfacial tension.
Water miscibility of hydric solvent can be determined by mixing the solvent with water and measuring turbidity as an indicator of solubility. When mixtures are less than fully transparent, the mixture is no longer a molecular solution. Hydric solvents that are fully miscible with water at ambient temperature and shower temperature tend to work well in helping with microemulsion formation. A spectrophotometer can be used to measure miscibility by optical clarity, by measuring % light transmission at a visible wavelength of light such as 640 nm. Hydric solvent is added in increasing amounts to water, measuring optical clarity. When all mixtures are optically transparent, the solvent is fully water miscible. If some mixtures are less than transparent, the concentration of hydric solvent at the onset of turbidity is its aqueous solubility.
Perfume miscibility of a hydric solvent can be determined by mixing the solvent with a representative perfume or perfume molecule and measuring optical clarity. When the perfume-solvent mixture is less than fully transparent the mixture is no longer a molecular solution. Hydric solvent is added until past the point of optical clarity, using a spectrophotometer to measure % Transmission for the mixture at an optical wavelength. Perfume miscibility is defined as the highest percentage of hydric solvent that can be added to a perfume, based on the weight of the two, which remains optically clear, i.e., generally 100% T at 640 nm (minus a small amount of absorbance, but not scattering). Exemplary hydric solvents are at least 10%, 15%, 20%, or 40 wt% miscible in the target perfume based on total weight of the perfume-solvent mixture. When solvent is miscible with both perfume and water, surface tension between the water and perfume phases in a composition can be lower, which creates optimal conditions for the formation of a microemulsion. When miscibility with both water and perfume is even higher, i.e., as high as 100%, solvent located in a microemulsion core with perfume can rapidly migrate to the aqueous phase during product use. The abundance of additional water during cleansing thus can reduce solvent in the microemulsion perfume core, reducing its action as a perfume solvent. This increases the thermodynamic activity coefficient of the perfume allowing it to both bloom in the shower and partition into the skin to provide superior scent longevity.
Perfume miscibility of a hydric solvent can vary by perfume since each perfume has unique chemical components. Perfume miscibility can be measured for a particular solvent in a specific perfume, such as the table below demonstrates for the perfume having the components listed below and used in the first series of composition examples further below.
A perfume, perfume X, was used having these below in addition to other components, the components below were identified from the spectra, area counted and summed per the PHADD method disclosed herein. PRM (KI): Alpha pinene (940), camphene (955), myrcene (990), para-cymene (1028), d-limonene (1034), eucalyptol (1037), dihydromyrcenol (1071), alpha terpinene (1022), linalool (1107), camphor (1154), methyphenylcarbinyl acetate (1193), florol major 2 (1197), allyl amyl glycolate major (1234), linalyl acetate (1254), coranol (1275), 1H-Indene,2,3-dihydro-1,1,2,3,3-pentamethyl (1325), neryl acetate (1364), cyclemax (1427), coumarin (1449), gamma methyl ionone (1491), butylated hydroxyl toluene (1519), cashmeran (1517), methyldihydrojasmonate (1663), cis-hexenyl salicylate (1680), Iso-E Super Major (1686), Helvetolide major (1727), ambroxan major 2 (1791), galaxolide (1874).
| ||Perfume X miscibility (% of solvent added)|
|* Dow Chemicals Carbowax Sentry PEG 300 average molecular weight|
Surfactant miscibility of a hydric solvent can also be important to ability of the microemulsion to form. Preferred hydric solvents can form an optically transparent mixture when 45 parts surfactant are mixed with 30 parts hydric solvent and 25 parts water, which mixture can absorb an additional 30 parts of perfume oil while remaining optically clear.
When a hydric solvent meets these aforementioned criteria, generally a transparent microemulsion can be formed in the presence of perfume and surfactant with the solvent such that the composition can absorb at least 0.5 parts of perfume oil:surfactant while retaining optical clarity. Generally, a micelle is only capable of absorbing 25% perfume oil by weight of the surfactant. Whereas microemulsion compositions can absorb 50% or 75% or 100% or more, of the weight of the surfactant, in perfume oil while retaining optical clarity. In some cases, it may take a day or more for the microemulsion to spontaneously form at ambient temperature, to establish the equilibrium phase behavior.
The hydric solvent that is miscible with water and many perfumes is glycol. Glycols may have a mixture of isomers. One exemplary glycol class is diols where the alcohol groups are separated by no more than 2 carbons on average. Suitable glycols can include, for example, dipropylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, or combinations thereof. Glycols can include pure materials and mixtures of isomers. For example, hexylene glycol includes 1,6-hexane diol; 1,4-hexane diol; or methyl pentanediol structures having 2 alcohol groups, etc.
Hydric solvents can modify the rheological properties of the composition, particularly reducing the viscosity. It was previously discussed that concentrating a composition into a gel is one way to combat low viscosity to improve dispensing and spreading characteristics. These types of compositions often exhibit a classic x-ray diffraction pattern of a lamellar phase. However, when the level of hydric solvent is greater than 40%, by weight of the surfactant, it can be difficult to form a structured gel and thus the composition can have a much lower viscosity and is difficult to dispense from conventional body wash packages. When composition with an exemplary rheology profile are desired, an intermediate level of hydric solvent can be used to deliver both exemplary rheology and perfume delivery properties. Thus, the hydric solvent can be from 10% to 40%, from 12% to 40%, from 15% to 35%, from 17% to 35%, from 20% to 30%, expressed as a weight percent of the surfactant.
Perfume is a benefit agent. Perfume benefits can be realized at different time points for cleansing compositions. Perfume in the package headspace can be important to select a product at the time of purchase. Perfume scent during cleansing, upon introduction of modest amounts of water, such as for example 3 parts of water per part composition (i.e., a 3:1 dilution ratio), provides a benefit during skin cleansing. During skin cleansing, some perfume can partition into the outer layers of the skin or hair, which can provide a scented skin or hair benefit for a period of time after cleansing, called scent longevity. A governing property for both scent bloom and longevity is the activity coefficient of the perfume molecules, which is a thermodynamic term. Perfume molecules exhibit their maximum vapor pressure only when they are pure. Diluted perfume molecules, whether diluted by surfactant in a micelle, organic solvent, water, etc., exhibit less than their pure vapor pressure. The amount of perfume in a headspace over a composition, diluted composition, or over the skin or hair can be measured analytically, as described in the methods section below. Benefits in initial fragrance intensity, bloom, or longevity can be demonstrated by comparing performance of the compositions before, during, and, or after a skin or hair cleansing event, compared to conventional body wash or shampoo compositions.
In addition to being a benefit agent, perfume is an oil and therefore can be a direct contributor to formation of phases responsible for its activity coefficient (as noted above), and therefore to scent bloom and longevity benefits. As discussed above, perfume oil can generally be added into micelle surfactant mixtures only to 0.25 weight fraction of the surfactant before it phase separates, whereas diluted cleansing compositions described herein can hold at least 0.5 parts perfume:surfactant, or even 0.75 parts perfume:surfactant, or even more, while remaining transparent, including water diluted compositions. The ability to hold large amounts of perfume in this manner while remaining transparent, isotropic and low viscosity is an indication the diluted composition is a microemulsion phase and is suitable for enhanced perfume benefits.
Perfume can be a carrier for non-scented, hydrophobic additives. Additives which are at least 5 wt%, or at least 10 wt%, or at least 20 wt% miscible with perfume may be employed to increase delivery of the additives to the skin or hair. Any additive which provides a benefit to the skin or hair or the skin environment (e.g., the skin microbiome) may be employed. The additive may provide a direct or indirect benefit, such as antibacterial, antihyperproliferative, antiinflammatory, chelation , pH regulation, antifungal, antiviral, control of disorders such as acne, atopic dermatitis, eczema, dermatitis, dandruff, antiaging, antiwrinkle, age spot reduction, sunscreen, hydration, moisturization, or any other skin benefit. An advantage of the present compositions is enhanced additive delivery to the skin or hair during cleansing. A further benefit is reduction in activity coefficient of the additive by dilution with perfume is transient due to subsequent evaporation of the perfume on the skin, which increases the thermodynamic activity of the additive after its delivery to the skin.
In addition, some compositions may form microemulsions but perform poorly for lathering and hence cleaning, which are important features for consumers. Compositions which effectively deliver perfume as described above, can also have consumer acceptable lather properties. Lather can be measured in accordance with the Cylinder Method described below. Compositions may have a lather volume of 300 mL, 400 mL, 500 mL, 600 mL, 700 mL, or more. Compositions may have a lather density of 0.03 g/cc, 0.04 g/cc, 0.05 g/cc, 0.055 g/cc, 0.06 g/cc, 0.065 g/cc, or more. Compositions may have a lather mass of 20 g, 25 g, 30 g, 35 g, 40 g, 45 g, or more.
In accordance with the above, a cleansing composition comprises a surfactant, a hydric solvent, perfume, and water. Additionally, optional ingredients may also be included as noted herein, for example, preservatives, thickeners, hydrophobic oils, pH modifiers, additives, soap, etc. Optional ingredients can be include at a level of 0.1% to 5%, by weight of the composition, for example. The cleansing composition is not in the form of a ringing gel. The cleansing composition can be in the form of a microemulsion or may contain a microemulsion phase. At least a portion of the cleansing composition may become a microemulsion upon dilution with water of 2:1 or 3:1 by weight (water:composition) to 10:1 by weight (water: composition).
A rinse-off cleansing composition includes surfactant, wherein the surfactant comprises a first branched anionic surfactant and a cosurfactant. Surfactants can provide a cleaning benefit, lather properties, and rheology properties to the compositions. The surfactant may be a single surfactant or a combination of multiple surfactants. In addition, a surfactant may be branched, linear, or a combination thereof. A composition may comprise from 20% to 34%, from 20% to 32%, from 20% to 30%, from 22% to 30%, or from 24% to 28%, by weight of the composition, of surfactant. The previous weight percentages of surfactant in the composition include primary surfactant and a cosurfactant.
The surfactant may be anionic, zwitterionic, amphoteric, nonionic, or a combination thereof. The surfactant includes a first branched anionic surfactant and a cosurfactant. The rinse-off cleansing composition may include from 14% to 34%, from 15% to 30%, from 15% to 25%, from 16% to 30%, from 15% to 20%, or from 17% to 25%, by weight of the composition, of an anionic surfactant.
The anionic surfactant can be linear or branched under the proviso that the composition comprises at least a branched anionic surfactant and a cosurfactant. The anionic surfactant can contain any counterion such as sodium, potassium, ammonium, triethanolamine, etc. The hydrocarbon chain can be an olefin or be branched or linear or cyclic, such as alkyl benzenes, and generally has between 10 and 20 carbons or 12 to 16 carbons. The anionic surfactant can comprise ethylene oxide groups, such as one EO, or two EO, or three EO, e.g., and can be a sulfate, sulfonate or carboxylate, including acidic sulfonates such as sulfosuccinates. Some exemplary anionic surfactants include a sulfate, an alkyl ether sulfate, an alkyl ether sulfate with 0.5 to 5 ethoxylate groups, sodium trideceth -2 sulfate, or a combination thereof.
Suitable anionic surfactants can include, for example, sodium trideceth sulfate and sodium laureth sulfate. These materials can have varying levels of ethoxylation. Thus, the levels of ethoxylation are represented by an (n), for example, sodium trideceth-n sulfate. n can range from 0.5 to 5. Some exemplary anionic surfactants are sodium trideceth-2 sulfate, sodium trideceth-3 sulfate, sodium laureth-1 sulfate, sodium laureth-2 sulfate, sodium laureth-3 sulfate, or combinations thereof.
The rinse-off cleansing composition may include from 1% to 15%, from 2% to 10%, or from 4% to 8%, by weight of the composition, of a cosurfactant. The cosurfactant may be, for example, zwitterionic surfactant, amphoteric surfactant, nonionic surfactant, or a combination thereof. Suitable amphoteric or zwitterionic surfactants can include those described in U.S. Patent No. 5,104,646
and U.S. Patent No. 5,106,609
Additional amphoteric detersive surfactants suitable for use in the rinse-off cleansing compositions can include those surfactants broadly described as derivatives of aliphatic secondary and tertiary amines in which an aliphatic radical can be straight or branched chain and wherein an aliphatic substituent can contain from 8 to 18 carbon atoms such that one carbon atom can contain an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within this definition can be sodium 3-dodecyl-aminopropionate, sodium 3-dodecylaminopropane sulfonate, sodium lauryl sarcosinate, N-alkyltaurines such as the one prepared by reacting dodecylamine with sodium isethionate according to the teaching of U.S. Patent No. 2,658,072
, N-higher alkyl aspartic acids such as those produced according to the teaching of U.S. Patent No. 2,438,091
, and products described in U.S. Patent No. 2,528,378
. Other examples of amphoteric surfactants can include sodium lauroamphoacetate, sodium cocoamphoacetate, disodium lauroamphoacetate disodium cocodiamphoacetate, and mixtures thereof. Amphoacetates and diamphoacetates can also be used.
Zwitterionic surfactants suitable for use in the rinse-off cleansing compositions are well known in the art, and include those surfactants broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which aliphatic radicals can be straight or branched chains, and wherein an aliphatic substituent can contain from 8 to 18 carbon atoms such that one carbon atom can contain an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Other zwitterionic surfactants can include a betaine, like an alkyl betaine or alkyl amidopropyl betaine, like cocoamidopropyl betaine.
Nonionic surfactants suitable for use can include those selected from the group consisting of alkyl ethoxylates, alkyl glucosides, polyglucosides (e.g., alkyl polyglucosides, decyl polyglucosides), polyhydroxy fatty acid amides, alkoxylated fatty acid esters, sucrose esters, amine oxides, or mixtures thereof. Some exemplary nonionic surfactants can include cocoamide monoethanolamine, decyl glucoside, or a combination thereof.
A rinse-off cleansing composition includes a perfume. A composition may comprise from 4% to 25%, from 4% to 30%, from 5% to 20%, from 6% to 15%, from 6% to 30%, from 7% to 25%, from 8% to 20%, from 8% to 15%, from 4% to 15%, or from 4% to 10%, by weight of the composition, of perfume.
Perfume may include solvents such as triethyl citrate, isopropyl myristate, dipropylene glycol, or others, to help, for example, with the miscibility of the perfume molecules with each other or to reduce cost. Generally these perfume solvents provide minimal or negligible effects on surfactant compositions as a whole due to the low amount of perfume in the total composition and the amount of solvent in a perfume can be ignored. However, when solvent in the perfume accounts for more than 5 wt% of the total hydric solvent in the cleansing composition, it should be accounted for. For example, when a perfume containing 10% hydric solvent is added to a cleansing composition at a level of 10 wt.% and the composition has 10 wt.% of added hydric solvent, the 1 wt. % of hydric solvent from the perfume accounts for a 9% increase in hydric solvent in the cleansing composition (1/11). Since this is more than a 5% change in the hydric solvent in the composition, it is important. In this case, hydric solvent from the perfume is added (mathematically) to the hydric solvent from other sources added to the composition; and perfume is considered to comprise only the scented molecules and not the solvent, which is subtracted from the wt% perfume in the composition.
In addition, the weight ratio of perfume to surfactant can impact the ability of the composition to provide an enhanced fragrance benefit. Without being limited by theory, it is believed at least some of the perfume benefits, like bloom and residual scent are derived from an abundance of perfume on the basis of its relation to the surfactant due at least in part to the interaction of the perfume with surfactant as the composition is diluted. Perfume is soluble in surfactant micelles only to 25% by weight of the surfactant. Above this level, the composition can become unstable unless steps are taken to form a phase to accept the abundance of perfume. However, forming those phases for stability of the perfume circles the composition back to where the perfume is bound within the composition and difficult to release. As such, a rinse-off cleansing composition comprises from 10% 12%, 15%, 20%, 25%, 30% 35%, 40%, 50%, 70%, to 30%, 40%, 50%, 60%, 70%, 90%, 100%, or 150%, by weight of the surfactant, of perfume.
Perfumes generally contain a broad range of perfume molecules (PRM) having diverse properties. It is an oversimplification to suggest all of the perfume is in a particular location, like in the core of a microemulsion. The real picture is more complex, with perfume molecules in dynamic equilibrium and structures such as micelles and microemulsions can be percolating. Further, some perfume molecules may favor being among surfactant tails or even in the aqueous phase instead of the microemulsion core. In short, all perfume molecules within a perfume mixture do not behave identically. Certain generalizations are useful to explain observed behaviors without inferring that all molecules in a perfume behave identically. For our purposes, a broad array of perfume molecules in a perfume mixture are analyzed by averaging or summing their performance.
Certain perfume features may also impact perfume benefits, such as the proportion of perfume molecules within a volatility or molecular weight range. In general, Kovats Index (KI) is a useful parameter to differentiate perfume molecules. Perfume molecules having KI less than 1100 can be considered high blooming molecules; those having KI greater than 1400 can be considered high skin partitioning molecules; and those between (KI of 1100-1400) can be considered middle perfume notes which generally favor neither bloom nor skin partitioning, but contribute to some extent in both.
Perfume can be tailored to enhance features of the compositions. For example, while the compositions, including diluted compositions during use, can have a high activity coefficient, perfume molecules may selectively evaporate to enhance bloom or partition into the skin depending on their individual vapor pressure. It has surprisingly been discovered that the weight percentage of middle notes can impact the fragrance expression of the composition for the initial scent, for bloom and delivery on the skin. Particularly, better expression of the perfume is accomplished when the weight percentage of middle notes is restricted. For example, the composition may comprise a perfume, wherein the weight percentage of the perfume components having a Kovats Index of 1100 to 1700 comprises from 0% to 70%, from 5% to 50%, from 5% to 30%, or from 5% to 20%, by weight of the perfume.
In addition, it has also been discovered that the weight percentages of the perfume raw materials in a perfume composition can provide a strong rheological effect on the rinse-off cleansing composition. The wt% proportion of low, mid and high KI materials in the perfume impacts the elastic and viscous modulus of the composition as well as the viscosity. In general having a greater proportion of low KI materials results in a reduction in G' and G" and a lower tan delta (ratio of G"/G'). The following models of G' and G" were developed based on samples containing various proportions of low, mid and high KI materials and is a demonstration of the impact of KI on rheological properties for an exemplary concentrated body wash composition. G' = 637.5 - (1.118*wt% of Low KI Materials in a perfume) + (2.879*wt% proportion of Mid KI Materials in a perfume) and G" = 7.510 + (0.4056*wt% of Mid KI Materials in a perfume) + (0.6140*wt% of High KI materials in a perfume).
A rinse-off cleansing composition includes a hydric solvent. A rinse-off cleansing composition may comprise from 3% to 20%, from 4% to 18%, from 5% to 16%, from 5% to 15%, from 6% to 14%, or from 4% to 10%, by weight of the composition, of the solvent.
The hydric solvents include dipropylene glycol (a glycol ether), diethylene glycol, dibutylene glycol, hexylene glycol, butylene glycol, pentylene glycol, heptylene glycol, propylene glycol, a polyethylene glycol having a weight average molecular weight below 500, or a combination thereof. One example of a polyethylene glycol is PEG 300. Isomers are included in the generally descriptive solvents listed, for example, butylene glycol is meant to included 1,2-butanediol and 1,3-butanediol and 1,4-butanediol. When solvents are solid in the pure form (e.g., 1,6-hexanediol), they can be melted during the making process and are effective hydric solvents. The composition comprises at least 3%, 4%, 5%, 6%, 8%, 10%, or 12%, to 10%, 12%, 15%, 20%, 25%, 30%, 35%, or 40%, by weight of the composition, of hydric solvent.
In addition, a cleansing composition may comprise from 8%, 10%, 12%, 14%, 16%, 17%, 20%, 25%, 30%, 40%, 50%, or 60%, to 40%, 50%, 60%, 70%, 80%, 90%, or 100%, or any combination thereof, by weight of the surfactant, of hydric solvent. For example, a cleansing composition can have 6%, by weight of the composition, of hydric solvent, and 44.5%, by weight of the composition, of surfactant. Hydric solvent levels can be expressed as a percent of the surfactant because the solvent molecules can engage with the surfactant molecules.
An intermediate level of hydric solvent can be used to deliver both a combination of exemplary rheology and perfume delivery properties. Thus, the hydric solvent can be from 10% to 40%, from 12% to 40%, from 15% to 35%, from 17% to 35%, from 20% to 30%, expressed as a weight percent of the surfactant.
A solvent may also comprise a non-hydric solvent. Examples of non-hydric solvents include propylene carbonate, butanol, pentanol, hexanol, propylene glycol ethers, butyl butanoate, propyl propanoate, isopropyl propanoate, or a combination thereof. One example of a propylene glycol ether is propylene glycol monomethylether. The non-hydric solvent may comprise less than 25%, 20%, 15%, 10%, or 5%, by weight of the solvent.
A rinse-off cleansing composition includes water. Water may come in with other components or may be added as free water. A rinse-off cleansing composition may comprise from 10% to 73%, from 20% to 70%, from 30% to 70%, from 40% to 65%, from 50% to 70%, or from 50% to 65%, by weight of the composition, of water.
In addition, the total weight percent of water and solvent can be important in the composition since this defines the amount of solvent phase in which the microemulsion or surfactant structures are distributed. The total amount of solvent phase (approximately, the additive inverse generally of the surfactant level) is a key driver of surfactant phases due to proximity of surfactants. Thus, the composition may comprise from 13% to 93%, from 20% to 90%, from 30% to 85%, from 40% to 75%, by weight of the composition, of the combination of water and solvent.
E. Rheology - Viscoelasticity and Viscosity
The rheological properties of rinse-off cleansing compositions can be characterized by viscoelastic parameters and a viscosity. The rheology of a composition can be defined by its G' and G" values, relating to the composition's structure. G' and G" are measured in accordance with the rheological properties method discussed herein. G' and G" describe a cleansing compositions elastic and viscous response to applied stress, characterizing how the material acts when dispensed from a bottle, sitting on the consumers implement or hand, and how a product spreads on application. It also impacts a consumer's perception of the product, for instance products with low G' values flow too readily in use and are associated in consumer perception and can be perceived as dilute. personal cleansing products, Conversely products with a high G' are associated in consumer perception with concentrated personal cleansing products. The cleansing composition may have a G' at 1 Hz of 25 Pa to 3000 Pa; from 50 Pa to 2500 Pa, from 100 Pa to 1500 Pa, or from 150 Pa to 1000 Pa. The cleansing composition may have a G" at 1 Hz of 20 Pa to 250 Pa; from 35 Pa to 200 Pa, from 40 Pa to 150 Pa, or from 50 Pa to 100 Pa.
In addition, the cleansing composition should have a viscosity sufficient to allow it to be dispensed from a package onto an implement or directly onto the skin. The viscosity of a rinse-off cleansing composition is measured in accordance with the rheological properties method discussed herein. The cleansing composition may have a viscosity at 0.10 1/sec of 10 PaS to 1200 PaS; from 20 PaS to 1000 PaS, from 30 PaS to 500 PaS, or from 40 PaS to 300 PaS. The cleansing composition may have a viscosity at 1 1/sec of 1 PaS to 30 PaS; from 1 PaS to 20 PaS, from 1 PaS to 15 PaS, or from 1 PaS to 10 PaS.
Compositions can also be highly shear thinning, having a viscosity ratio of less than 0.20, or 0.10, or even less than 0.05, which is the ratio of the viscosity at 1 1/sec divided by the viscosity at 0.10 1/sec.
Liquid cleansing compositions often have a high water activity (i.e. 0.95 or more). Water activity describes the availability of water within a composition to support various chemical and biological processes requiring water. Compositions with high water activity can allow growth of microorganisms and therefore generally require preservatives. For example, bacteria can grow at a water activity of 0.90 or above and fungus can grow at a water activity of 0.70 or above. Below these water activities, microorganisms generally dehydrate and die.
The rinse-off cleansing compositions as noted herein can have a low water activity, less than 0.90. This low water activity allows the compositions to naturally resist the growth of microorganisms and thus utilize minimal or even no, preservative. In addition, the use of high levels (5 wt. % or more) of glycols, like dipropylene glycol, can also help to prevent the growth of microorganisms and further support a composition which needs minimal or even no, preservative.
G. Hydrophobic Oils
The rinse-off cleansing composition may comprise a hydrophobic oil. Hydrophobic oil can help form a microemulsion phase due to low solubility in the palisade layer of micelles, to further enhance bloom and deposition on skin. The rinse-off cleansing composition may comprise from 0% to 25%, from 2% to 20%, or from 3% to 15% by weight of the composition, of a hydrophobic oil. Exemplary hydrophobic oils can include, for example, isopropyl myristate, isostearyl isostearate, behenyl behenate, triglycerides such as soybean oil, hydrocarbon such as mineral oil, or combinations thereof.
The rinse-off cleansing composition may comprise an additive. Additives are materials that are at least partially soluble in the perfume. It is believed that additives which are at least partially soluble in the perfume will also see a deposition benefit. Additives which are at least 5 wt%, or at least 10 wt%, or at least 20 wt% miscible with perfume may be employed to increase delivery of the additives to the skin or hair. Some examples of classes of material that can be soluble in the perfume are skin actives, vitamins, antibacterials, antifungals, chelants, or combinations thereof.
Examples of skin actives which can be included are sunscreens; anti-acne medicaments; antioxidants; skin soothing agents, skin healing agents; essential oils, skin sensates, anti-wrinkle medicaments, or mixtures thereof. Some examples of skin soothing agents can include, for example, aloe vera, allantoin, bisabolol, dipotassium glycyrrhizinate, or combinations thereof.
Examples of vitamins which can be included are Vitamin A (e.g., beta carotene, retinoic acid, retinol, retinoids, retinyl palmitate, retinyl proprionate, etc.), Vitamin B (e.g., niacin, niacinamide, riboflavin, pantothenic acid, etc.), Vitamin C (e.g., ascorbic acid, etc.), Vitamin D (e.g., ergosterol, ergocalciferol, cholecalciferol, etc.), Vitamin E (e.g., tocopherol acetate, tocopherol nicotinate, etc.), Vitamin K (e.g., phytonadione, menadione, phthiocol, etc.), or combinations thereof.
Examples of antibacterials and/or antifungals which can be included are glycolic acid, lactic acid, phytic acid, N-acetyl-L-cysteine, phenoxyethanol, phenoxypropanol, phenoxyisopropanol, zinc pyrithione, octopirox (piroctone olamine), climbazole, ketoconazole, thymol, terpineol, essential oils, or combinations thereof.
Examples of chelants which can be included are 2-aminoethyl phosphoric acid (AEP), N-phosphonomethyl aminodiacetic acid (PMIDA), 1-hydroxyethane-1,1-diphosphonic acid (HEDP), amino tris(methylene phosphonic acid) (ATMP), ethylenediamine tetra(methylene phosphonic acid) (EDTMP), diethylenetriamine penta(methylene phosphonic acid) (DTPMP), phytic acid, nitrilotrimethylene phosphonic acid (NIP), 2-hydroxypyridine oxide (HPNO), or combinations thereof.
The rinse-off cleansing composition may comprise from 1% to 20%, from 2% to 10%, or from 3% to 8%, by weight of the composition, of an additive.
The rinse-off cleansing composition may comprise from 0.1% to 4% by weight of the composition of a thickener. Preferred thickeners are hydrophilic such as cellulose derivatives, hydrophobically modified celluloses, starches and starch derivatives, polyacrylates including hydrophobically modified polyacrylates and polyacrylamides, bacterial polymers such as xanthan gum, tree and plant gums such as guar, insoluble thickeners such as cellulose.
Rinse-off cleansing compositions as described herein may also comprise soap.
Compositions can be dispensed from a squeezable package with an orifice, such as a conventional body wash or shampoo package. The package can be a compact package, i.e., contain less than 250 ml, or 200 ml, or 150 ml of volume to signal the contents are concentrated. The shear thinning compositions can be dispensed from a package with a slit valve orifice or other flexible orifice, which is generally cut from a silicone elastomeric material and inserted into an orifice housing. When the composition has a low viscosity, less than 0.25 PaS at 1 1/sec, it can be dispensed from a foaming package such as a pump foamer. Compositions can also be dispensed from liquid pump packages.
In addition to the compositional elements and parameters noted above, it is believed there are also some inventive benefits and/or uses to the compositions which are set out as methods below. For the sake of brevity, all of the compositional elements and parameters noted above are not repeated herein, but can be used within the methods where relevant.
A method of enhancing fragrance of a rinse-off cleansing composition before use, comprising, combining: a) from 20% to 34%, by weight of the composition, of surfactant; b) from 4% to 30%, by weight of the composition, of a perfume, wherein the weight percent of perfume is from 10% to 90%, by weight of the surfactant; c) from 3% to 20%, by weight of the composition, of a solvent, wherein at least 3% of the solvent, by weight of the composition, comprises a hydric solvent and wherein the weight percent of the hydric solvent is from 8% to 60%, by weight of the surfactant; and d) from 10% to 73%, by weight of the composition, of water; wherein the rinse-off cleansing composition has a G' at 1 Hz of 25 Pa to 3000 Pa, and wherein the composition has a total GCMS count higher than that of a control where the solvent is replaced with water, when the total GCMS count is measured in accordance with the PHADD method at zero dilution. The composition may have a GCMS total count of 10% more than the control, 15%, 20%, 25%, 50%, 75%, 100%, 150%, 200%, 250%, or even 300% more than the control.
A method of enhancing in-vitro bloom of a rinse-off composition, comprising, combining: a) from 20% to 34%, by weight of the composition, of surfactant; b) from 4% to 30%, by weight of the composition, of a perfume, wherein the weight percent of perfume is from 10% to 90%, by weight of the surfactant; c) from 3% to 20%, by weight of the composition, of a solvent, wherein at least 3% of the solvent, by weight of the composition, comprises a hydric solvent and wherein the weight percent of the hydric solvent is from 8% to 60%, by weight of the surfactant; and d) from 10% to 73%, by weight of the composition, of water; wherein the rinse-off cleansing composition has a G' at 1 Hz of 25 Pa to 3000 Pa and wherein the composition has a total GCMS peak area at the 3:1 dilution point which is at least 1.5 times greater than the GCMS peak area of the composition prior to dilution when measured in accordance with the PHADD method. The composition may have a GCMS peak area of 1.75 times more than the composition prior to dilution, 2 times, 2.25 times, 2.5 times, 3 times, or even 4 times or more, more than the composition prior to dilution.
A method of enhancing fragrance of a rinse-off cleansing composition on skin or hair, comprising, combining: a) from 20% to 34%, by weight of the composition, of surfactant; b) from 4% to 30%, by weight of the composition, of a perfume, wherein the weight percent of perfume is from 10% to 90%, by weight of the surfactant; c) from 3% to 20%, by weight of the composition, of a solvent, wherein at least 3% of the solvent, by weight of the composition, comprises a hydric solvent and wherein the weight percent of the hydric solvent is from 8% to 60%, by weight of the surfactant; and d) from 10% to 73%, by weight of the composition, of water; wherein the rinse-off cleansing composition has a G' at 1 Hz of 25 Pa to 3000 Pa, and wherein the composition has a total GCMS count higher than that of a control where the solvent is replaced with water when the total GCMS count is measured in accordance with the PSHAM method. The composition may have a GCMS total count of 10% more than the control, 15%, 20%, 25%, 50%, 75%, 100%, 150%, 200%, 250%, or even 300% more than the control.
A method of enhancing fragrance longevity of a rinse-off cleansing composition on skin or hair, comprising, combining: a) from 20% to 34%, by weight of the composition, of surfactant; b) from 4% to 30%, by weight of the composition, of a perfume, wherein the weight percent of perfume is from 10% to 90%, by weight of the surfactant; c) from 3% to 20%, by weight of the composition, of a solvent, wherein at least 3% of the solvent, by weight of the composition, comprises a hydric solvent and wherein the weight percent of the hydric solvent is from 8% to 60%, by weight of the surfactant; and d) from 10% to 73%, by weight of the composition, of water; wherein the rinse-off cleansing composition has a G' at 1 Hz of 25 Pa to 3000 Pa, and wherein the composition has a total GCMS count higher than that of a control where the solvent is replaced with water when the total GCMS count is measured in accordance with the PSHAM method at 1 hour after the initial application. The PSHAM method may also be evaluated at other time points, for example, 2 hours, 3 hours, 3.5 hours, 4hours, etc. after the initial application. The composition may have a GCMS total count of 10% more than the control, 15%, 20%, 25%, 50%, 75%, 100%, 150%, 200%, 250%, or even 300% more than the control.
The examples are prepared by weighing the components together into a Speedmixer pot, stirring by hand briefly to homogenize the fluids, and then speedmixing for 60 seconds at 2750 rpm.
Example 1 is not an embodiment of the claimed invention but is useful for understanding the invention.
| ||Ex. 1|
|Sodium trideceth-2 sulfate
|G' at 1 Hz (Pa)
|Viscosity at 1 sec-1 (PaS)
|Hydric solvent as percent of surfactant
|Perfume as percent of surfactant
Example: Delivery of perfume to skin from a cleansing composition
Delivery of perfume to the skin was measured for Ex. 1 and a control composition according to the PSHAM method using 4 subjects. One arm is washed with Ex. 1 and the opposing arm with the control (a micelle body wash comprising 9 wt% sodium laureth-3 sulfate, 1 wt% cocoamidopropyl betaine, 2.5 wt% sodium chloride and 1.08 wt% of the identical perfume). For the control, 10 ml of body wash was dosed into a wet puff, lathered for 15 seconds with the hands, used to wash the arm for 15 seconds, then rinsed for 15 seconds. For the inventive composition, 1.7 ml was used in the same manner.
The dramatic increase in total headspace counts collected over the arms with Ex. 1 versus the control illustrates an increase in the amount of perfume deposited on the skin during the cleansing process.
| ||Control arms||Ex. 1 arms|
|Total headspace counts collected over arms at time zero (average of arms for 36 perfume components)
|Ratio to control
a) G' and G" Test Method
To measure the viscoelastic properties of a personal care composition, the viscous (G") and elastic (G') moduli, use a rheometer such as a AR G2 Rheometer (TA Instruments, DE, USA) with 1 degree cone upper geometry with a diameter of 40 mm and flat plate lower geometry with Peltier heating/cooling to control temperature. Place approximately 1 gram of personal care composition onto the lower test geometry and lower the upper geometry into position, lock the geometry and wipe away excess composition to create an even surface around the edge of the geometry. Conduct the oscillatory test over frequency range of 0.01 to 100 Hz, collecting 5 data points per decade, using a constant oscillatory stress of 0.5968 Pa and a temperature of 25°C. The tan delta is calculated as the ratio of G"/G'.
Record the G' and G" (Pa) at a frequency of 1 Hz.
b) Ultracentrifuge Test
Compositions are considered to be in a single phase when they do not separate into layers or phases when ultracentrifuged for 2 hours at 50,000 rpm in an ultracentrifuge at 40°C (e.g., Beckman ultracentrifuge with swinging bucket rotor).
c) Viscosity Method
To measure the viscosity of a personal care composition use a rheometer such as an AR G2 Rheometer (TA Instruments, DE, USA) equipped with 1 degree cone upper geometry with a diameter of 40 mm and flat plate lower geometry equipped with Peltier heating/cooling to control temperature. Measurement can be conducted by placing approximately 1 gram of personal care composition onto the lower test geometry and lowering the upper geometry into position to the desired gap of 52 microns, wiping away any excess composition to create an even surface around the edge of the geometry. Conduct a continuous flow test at 25°C, controlling the shear rate and progressing from a shear rate of 0.01 to 100 1/sec over a time period of 3 minutes, running the test in log mode and collecting 15 points per decade. Record the viscosity (PaS) at the shear rates of interest, for the samples herein we have reported the viscosity at a shear rate of 0.10 1/sec and 1 1/sec, interpolating as needed to obtain values at shear rates.
d) Perfume Headspace Abundance During Dilution Method (PHADD)
1) Perfume headspace abundance for neat products
Unless otherwise indicated, all laboratory instruments are operated according to manufacturer's instructions. The following equipment is used: 20 mL headspace vials from Gerstel (Baltimore, MD); timer; gas chromatograph (GC) Agilent model 6890 and Gerstel MPS-2 auto sampler; GC column J&W DB5-MS, 30 m x 0.25 mm ID, 1.0 µm film thickness obtained from Agilent Technologies, Inc., Wilmington, DE, USA; carrier gas of ultra-pure helium, 1 mL/min. flow rate; solid-phase microextraction injection port liner (0.75mm ID) from Supelco; and a model 5973 Mass Selective Detector obtained from Agilent Technologies, Inc., Wilmington, DE, USA having a source temperature of 230 °C, and a MS Quad temperature of 150 °C.
1 gram of cleansing composition is placed into a clean 20mL headspace vial and a stir bar is added to the vial. A polytetrafluroethylene cap is placed on the vial and hand tightened. The sample is allowed to equilibrate to establish equilibrium of the perfume molecules between the composition and the headspace. This generally takes at least 30 minutes at room temperature. The sample is then analyzed using an automated solid phase microextraction-gas chromatograph-mass spectrometer (SPME-GC-MS) analysis system.
Transfer the sample vials to the auto sampler tray to begin analysis. Start the sequence of sample loading and analysis. Each sample vial is taken by the auto sampler to the incubation chamber and held at 30°C for 1 minute. The SPME fiber assembly is DVB/CAR/PDMS (50/30 um, 24 ga, 1 cm length). Sampling time is 1 minute. The samples are stirred at 500 rpm during SPME sampling. After sampling, the SPME fiber is injected into the GC injector. The injector temperature is 270°C.
The GC-MS analysis is started. SPME desorption time is 5 minutes. The following temperature program is used: i) an initial temperature of 50°C which is held for 0.5 minutes, and ii) increase the initial temperature at a rate of 8°C/min until a temperature of 275°C is reached, hold at 275°C for 2.5 minutes. Perfume compounds are identified using the MS spectral libraries of John Wiley & Sons and the National Institute of Standards and Technology (NIST), purchased and licensed through Agilent. Chromatographic peaks for specific ions are integrated using the MassHunter software obtained from Agilent Technologies, Inc., Wilmington, DE, USA. To calculate the perfume headspace abundance, all of the area counts of the perfume molecules are added together.
2) Perfume headspace abundance for diluted product
For the perfume headspace abundance for diluted product, use the method above for neat product, except 1.0 g of product is combined with sufficient water to reach the desired level of dilution, usually between (0.5-5g), a magnetic stir bar is added to each vial, and after the cap is in place, the vials are stirred via the magnetic bar for at least 30 minutes to equilibrate.
e) Perfumed Skin Headspace Abundance Method (PSHAM)
Unless otherwise indicated, all laboratory instruments are operated according to manufacturer's instructions. The following equipment is used: Stir Bar Sorptive Extraction Sampling Devices - Gerstel Twister, 2 cm in length with 1 mm PDMS (polydimethyl silicone) phase thickness; glass sampling cups with magnets to hold Twisters during sampling 35 mL in volume; timer; gas chromatograph (GC) Agilent model 7890 and Gerstel MPS-2 autosampler with thermal desorption unit (TDU) and cooled-on-column (CIS-4) temperature programmable inlet; GC column J&W DB5-MS, 30 m x 0.25 mm ID, 1.00 µm film thickness obtained from Agilent Technologies, Inc., Wilmington, DE, USA; carrier gas of ultra-pure helium, 1 mL/min. flow rate; liquid nitrogen for injection port cryogenic cooling; Gerstel TDU injection port liners with glass wool; and a detector model 5975 Mass Selective Detector obtained from Agilent Technologies, Inc., Wilmington, DE, USA having a source temperature of 230°C, and a MS Quad temperature of 150°C.
Headspace samples are collected from panelists' arms that have been washed with test products and/or controls. The wash protocol includes: 1) adjusting water temperature to 100°F and water flow to 1 gallon/min; 2) rinsing the arm under the water stream for 5 seconds; 3) apply product of known weight on a puff which has been prewetted for 5 seconds with water; 4) lather product in the puff by hands for 10 seconds; 5) wash the entire forearm for 15 seconds using back and forth motion, then wait for 15 seconds; 6) rinse the arm under the water stream for 15 seconds; 7) pat dry the forearm using a paper towel; and then 8) proceed to sensory evaluation or analytical sampling. The Twister device is held inside of the sampling cup with magnetic force while the cup is placed against panelists' arms for a period of 3 minutes. The Twister is then transferred to the thermal desorption tube and capped with a transport adapter.
To begin the analysis, transfer the Twister transport tubes to the autosampler tray and proceed with TDU-GC-MS analysis. Set-up the sequence of samples needing to be analyzed and start the sequence of sample loading and analysis. In this step, the Twister transport tube is taken by the autosampler to the thermal desorption unit where it is heated to 250°C and held at that temperature for 5 minutes. Perfume materials that are thermally desorbed from the Twister are trapped by the liquid nitrogen cooled inlet, which is held at 120°C during desorption. The programmable temperature inlet is then heated 275°C and held at that temperature for 3 minutes.
The GC-MS analysis run is started and the GC temperature program is initiated with mass spectrometer detection. The following temperature program is used: i) an initial temperature of 50°C which is held for 0.5 minutes, and ii) increase the initial temperature at a rate of 8°C/min until a temperature of 275°C is reached, hold at 275°C for 5 minutes. Perfume compounds are identified using the MS spectral libraries of John Wiley & Sons and the National Institute of Standards and Technology (NIST), purchased and licensed through Agilent. Chromatographic peaks for specific ions are integrated using the MassHunter software obtained from Agilent Technologies, Inc., Wilmington, DE, USA. Abundance of perfume in the headspace over the skin is calculated by adding the area counts of all the perfume molecules. The relative enhancement of abundance of perfume in the headspace using test products over control products is obtained by the ratio of the total peak area counts. The PSHAM measurement may be repeated on the target surface at later time intervals to test for longevity of fragrance on the skin. These time intervals could be any desired, for example, 1 hour, 2 hours, 3 hours, 3.5 hours, 4 hours, etc. after the initial application.
f) Cylinder Method
Lather can be measured in accordance with the Cylinder Method. Lather volume is measured using a graduated cylinder and a rotating mechanical apparatus. A 1,000 ml graduated cylinder is used which is marked in 10 ml increments, has a height of 14.5 inches at the 1,000 ml mark from the inside of its base, and has a neck at its top fitted for a plastic insert cap (for example, Pyrex No. 2982). Moderately hard water is prepared with 1.5:1 ion ratio Ca/Mg by dissolving 1.14 grams calcium chloride dihydrate and 1.73 grams magnesium chloride hexahydrate into one U.S. gallon distilled water. The water is maintained at between 105 - 110 °F. The graduated cylinder is heated to the same temperature by flushing with excess tap water at the same temperature for 15 seconds, then drying it outside and shaking briefly upside down to dry the interior. 100.0 grams of the moderately hard water at the indicated temperature is weighed directly into the graduated cylinder. The cylinder is clamped in a mechanical rotating device, which clamps the cylinder vertically with an axis of rotation that transects the center of the graduated cylinder. Using a 3- or 4-place metric balance, invert the plastic cap for the graduated cylinder onto the balance pan and weigh 0.500 grams of composition (for compositions less than 19% surfactant) to within 4 milligrams accuracy, using a holder to keep the cap level. When the surfactant level is 40% or greater, use 125 mg of composition (500 g/4). When it is between 30% and 39%, use 135 mg of composition, and when it is between 20% and 29% use 250 mg and for 19 wt% and below use 500 mg. Insert the cap into the graduated cylinder neck while being careful that all composition is now in the space in the cylinder interior. For compositions with very low viscosity which will not remain on the cap surface, 500 mg composition can be added directly to the graduated cylinder. Rotate the cylinder for 25 complete revolutions at a rate of 10 revolutions per 18 seconds to create a lather and stop in a level, vertical position. When the cylinder stops in a vertical position, start a digital stopwatch. Observing the water draining at the bottom, record the time to the nearest second when the water height measures 50 cc, then 60 cc, then 70 cc and so on until at least 90 cc has drained. Measure and record the total height of the foam in the column interior, which is the lather volume. If the top surface of the lather is uneven, the lowest height at which it is possible to see halfway across the graduated cylinder is the lather volume (ml). If the lather is coarse such that a single or only a few foam cells ("bubbles") reach across the entire cylinder, the height at which at least 10 foam cells are required to fill the space is the lather volume, also in ml up from the base. When measuring the lather height, bubbles that are larger than 1 inch across at the top surface are considered free air and not lather. The measurement is repeated and at least three results averaged to obtain the lather volume. In a spreadsheet, calculate the lather density at each observed time point as the volume of foam (total height minus water height) divided by the weight of the foam (100.5 grams minus the weight of water observed, using a density of 1.00 g/cc for water). Fit the 3 time points closest to (ideally, also bracketing) 20 seconds to a 2nd
order polynomial equation. Solve the equation for the lather density at 20 seconds, which is the lather density of the composition. Multiply the lather volume by the lather density to obtain the lather mass, in grams.
The entire process should take less than 3 minutes in order to maintain desired temperature.
g) Stability Test
A composition is filled into a 4 fl. oz. glass jar with minimal headspace and capped, placed in a dark room maintained at 40°C for 3 months. A composition is stable if there is minimal visual sign of phase separation and the viscosity changes by less than 90% from the original viscosity.