MXPA06005631A - Improved low ph detergent composition. - Google Patents

Abstract

A synergistic low pH cleansing composition comprising: i) 2 % to 30 % of soaps selected from sodium and potassium soap; ii) 30 % to 80 % of soaps selected from magnesium, calcium, zinc and aluminium soaps; and iii) 4 % to 25 % water.

Description

COMPOSITION OF IMPROVED LOW pH DETERGENT The present invention relates to low pH soap formulations, and in particular to synergistic and selective low pH soap formulations comprised of sodium and magnesium soap. The soap formulation of the invention would favor obtaining low pH formulations based on soap only, optionally non-soap detergents, thereby allowing the preparation of desired cleansing formulations with soaps, avoiding the problems associated with synthetic detergents, and also favoring the incorporation of pH-sensitive benefit agents in soap formulations. Usually, cleaning / soap formulations are provided for cleaning skin with active surface preparations. Since the skin is a sensitive substrate, there is always a need to provide a formulation that favors the effective cleaning of the skin smoothly and without causing irritation or problems to the surface of the skin, and delivering benefit agents such as skin lighteners, agents antibacterials, etc. Based on the above requirements, various formulations of cleaning composition are made available to suit various end-user benefits / utilities. Softness is considered one of the key requirements to maintain the appropriate skin benefits in the use of cleansing compositions. However, softness is sometimes achieved at the expense of frothing and cleaning benefits. In the alternative, in case of improved foaming characteristics requirements, it is frequently achieved by sacrificing the softness of the formulation. Therefore, depending on the use and specific application, cleaning formulations are designed. However, it is difficult and not always predictable in terms of the final properties and characteristics obtained from selective blends of fatty acid soaps and synthetic surfactants used. US Pat. No. 5,607,909 discloses a soft, foaming, personal cleansing bar composition, in weight from the bar comprising from 30 to 85 parts of designed fatty acid soap, from 3 parts to 30 parts of synthetic surfactant and from 15 to 35 parts of water, where the designed fatty acid soap is a mixture of 65% to about 95% sodium soap and 5 to about 35% magnesium soap (which is 1.5% to 30% soap) of magnesium in a global formulation). This prior art is specifically directed to a soft foaming stick, and essentially involves synthetic surfactants. US 5,387,362 refers to a personal cleansing bar made with a base soap designed with mixed counterions (Mg / K / Na), selected saturated C14-C18 fatty acid soap and selected soaps of water-soluble soaps selected from lauric , oleic and other minors. The level of sodium, potassium and magnesium is limited to 64%, 24% and 12%. This prior art is again directed to improvements in softness, while maintaining proper foaming / sudsing, rinsing and processing characteristics. It would be clearly evident from the foregoing that several combinations of personal cleansing bars are made available for the technique involving combinations of soap and non-soap / synthetic surfactants. Although softness, foaming, processability, etc. of formulations for cleaning sticks are usually focused during the formulation of such cleaning composition, the pH of the formulation is also associated with important product attributes, such as stability and delivery of benefit agents, and maintenance of natural lipids of the skin. US 5204014 discloses a low pH mild personal cleansing bar with soft foaming synthetic surfactants of about 20 to 50% and magnesium soap in the amount of 5 to 50%. The ratio of synthetic to Mg soap varied from 10: 1 to 0.4: 1 to obtain a pH in the range of 6.5 to 8.5 in 1% solution (25 ° C). Although this formulation claims a low pH bar, clearly involves the use of synthetic detergents to control soap pH, and also requires wax as an essential constituent. Although it is known that the use of synthetic surfactants as a replacement for soap contributes towards the decrease of the pH values of the cleaning bar compositions, a random or scattered replacement of bars of soap by syndet bars (synthetic detergent) has not been so far possible for a variety of reasons. This is mainly due to different physical characteristics of syndet bars as compared to bars of soap, such as, for example, dunking or soft dough, foam quality and rinsing. Therefore, the foregoing reveals the need for soap replacement to the extent possible by synthetic detergents to lower the pH values of the soap, because it is usually not possible to achieve pH formulations with only sodium soap, because the soap by itself contributes towards the high pH of such formulations. Thus, a basic objective of the present invention is to be able to provide synergistic pH cleaning compositions, which involve only soap and avoid or minimize the requirement of synthetic detergents to produce such low pH formulations. Another object of the present invention is to be able to provide synergistic low pH soap formulations, with selective soap combinations, which would allow obtaining formulations based on soap only, of low pH, and in the process to further achieve advantageous benefit characteristics. of soap formulations vis-a-vis synthetic detergents, and also to facilitate the incorporation of pH-sensitive benefit agents in soap formulations, thereby providing a wider application / application of soap formulations. Thus, according to a first aspect of the present invention a low synergistic pH cleaning composition is provided, comprising: i) 2% to 30% selected soaps of sodium and potassium soap; ii) 30% to 80% of selected soaps of magnesium, calcium, zinc and aluminum soaps; and iii) 4% to 25% water. It has been found by means of the invention, that the above selective formulation, which basically includes only soaps and is free of synthetic detergents, in the manner of a synergistic and selective combination of the soaps selected from sodium and potassium soap together with the soaps selected from magnesium, calcium, zinc and aluminum, unexpectedly provides a low pH soap formulation. It was also surprisingly found by means of the invention, that the presence of selective diluent, such as free fatty acid in combination with the soaps selected from sodium, potassium, magnesium, calcium, zinc and aluminum soaps, synergistically favors further lowering the pH of the soap formulation. Thus, according to another aspect of the invention, there is provided a low pH soap formulation comprising: soaps with or without synthetic detergents and other additives; and free fatty acid as a diluent in combination with at least one of the selected soaps of sodium, potassium, magnesium, calcium, zinc and aluminum soaps. In accordance with yet another aspect of the present invention, a synergistic, low pH cleaning composition is provided, comprising: i) 2% to 30% soap selected from sodium and potassium soap; ii) 30% to 80% soap selected from magnesium, calcium, zinc and aluminum soaps; Ii) up to 20% free fatty acid; and iv) 4% to 25% water. Still in accordance with yet another aspect of the present invention, there is provided a process for the manufacture of low pH soap formulations, comprising: i) providing 2% to 30% selected soaps of sodium and potassium soap; ii) provide 30% to 80% of selected soaps of magnesium, calcium, zinc and aluminum soaps; and iii) provide 4% to 25% water. According to another aspect, the process for manufacturing the low pH, synergistic soap formulation comprises: i) providing 2% to 30% soap selected from sodium and potassium soap; ii) provide 30% to 80% soap selected from magnesium, calcium, zinc and aluminum soaps; Ii) provide up to 20% free fatty acid; and iv) provide 4% to 25% water. The above formulations of the invention thus provide for low pH cleaning compositions that involve only soap and that avoid the requirement of synthetic detergents to produce such low pH formulations. In some embodiments, the compositions may be free (eg, contain less than about 5%, preferably less than about 3%, preferably less than about 1% and ideally may be completely free) of synthetic surfactant. This would allow to obtain formulations based only on soap, of low pH, and in the process to further achieve the advantageous benefit characteristics of soap formulation vis-à-vis its essential combinations with synthetic detergents to reduce pH as is known in the art. Importantly, soap-based formulations would, on the one hand, maintain the desired stick properties of a formulation vis-à-vis synthetic detergents, and would also facilitate the incorporation of pH-sensitive benefit agents into soap formulations, providing Therefore, a wider application or use of soap formulations. Importantly, the selective, low pH formulation above is based on a surprising finding that sodium / potassium soap, which usually has a high pH value when mixed selectively with magnesium, calcium, zinc soaps and aluminum, which have a lower comparative pH value in combination is usually guided by the pH of strongly alkaline sodium / potassium soap, except in selective concentrations of the mixture, which achieves a surprisingly lower pH for the combination. In fact, it was found that only for a selected concentration range, the mixture of sodium / potassium soap with magnesium / calcium / zinc / aluminum reaches a reduced pH, which is otherwise even at a lower magnesium / calcium / zinc / aluminum concentration and The higher pH (which is the soap that has lower pH) beyond the selected range, the combination pH is mainly determined by the high sodium / potassium pH values. It is also a finding of the present invention that under dilution in the presence of free fatty acid, the pH of sodium / potassium and magnesium / calcium / zinc / aluminum soaps can surprisingly be reduced even at less dilution.

Therefore, the invention and the above formulation provide selective advantages of such surprising findings of possible pH reduction of soaps by selective concentrations of blends of soaps, and also in the presence of small amounts of free fatty acids as a diluting agent. In this way, it is possible by means of the above selective combination, to achieve formulations of low pH with the soap, with or without the use of additional synthetic detergent for further reduction in pH. The compositions of the invention may include other conventional additives, such as, polyethylene glycol, sorbitol, glycerin and emollients and similar skin moisturizing agents, in addition to skin benefit agents such as sunblock, skin lightening, antibacterial and other agents. pH sensitive additives. As indicated above, the soap mixture is selected from sodium or potassium soap in combination with selected soap of magnesium, calcium, zinc and aluminum. According to a preferred aspect of the invention, the soap formulation may involve the addition of free fatty acid, as a diluent, which synergistically favors obtaining low pH formulations with soap base. The free fatty acid affects the foaming characteristics of the bars, and in particular surprisingly helps to lower the pH levels of the formulation, in addition to showing an improvement in softness. Advantageously, the presence of such free fatty acid favors obtaining an emollient effect, which tends to soften the skin, or otherwise improves the sensation on skin characteristics and cleans up any excess of alkalinity. Preferably, the suitable free fatty acid can be selected from stearic acid, hysteric acid, palmitic acid, myristic acid and lauric acid and mixtures thereof. Preferably, it may be present at a level of up to 20%, conveniently 0.1% to 15%, preferably 1% to 12%, optionally 5% to 10%. The formulation of the invention may optionally include synthetic detergent surfactants, which are typically selected from synthetic anionic, nonionic, amphoteric and zwitterionic detergents. Surfactants of water solubility / foaming both low and high, can be used together with synthetic detergent surfactants, suds reinforcers as good dispersants.

EXAMPLES The details of the invention, its objects and advantages are explained hereinafter in relation to non-limiting exemplary illustrations described hereinafter.

Examples 1 to 12 Under these examples, the pH of sodium and magnesium soaps of varying concentrations was studied individually and in combination. For this purpose, the following exemplary solutions of varying concentrations of sodium and magnesium soaps were obtained, as detailed below in Table I below.

TABLE The pH values of the respective solutions under Examples 1 to 12 were plotted against the product concentration, as shown in Figure 1. As would be apparent from Figure 1, as the concentration of sodium soap was increased in solution, the pH was raised stably and was always higher when compared with magnesium soap alone. In combination, a surprising and unexpected observation is evident since a sodium-magnesium soap mismatch does not necessarily provide a uniform mid-point along the sodium soap and mangesium pHs individually. The pH of the mixture is generally more towards the pH of the sodium soap, suggesting that sodium soap is a stronger alkaline buffer. However, it was selectively identified that at a selectively defined range of the combination, the pH is surprisingly lower than the rest of the trend. This according to the invention would allow the selective reduction of pH of formulations even based only on soap, without the need for synthetic detergents.

Examples 13 to 22 The following examples illustrate the effects of diluting sodium soap using diluents such as sorbitol and free fatty acid. The concentration of the diluent effects of both sodium and magnesium salts in combination with FFA / sorbitol was studied with concentrations of the solutions as detailed below in Table II.

TABLE II The pH of the above diluted sodium salt of Examples 13 to 22 was noted and compared to the pH of sodium laurate alone. The results are reproduced in the accompanying figure 2A.

Examples 23 to 32 The following examples illustrate the dilution effect of magnesium soap using diluents such as sorbitol and free fatty acid. The concentration of the diluent effects of magnesium salts in combination with FFA / sorbitol was studied with concentrations of the solutions as detailed below in Table III.

TABLE III The pH of the above diluted magnesium salt of Examples 23 to 32 was noted and compared to the pH of magnesium laurate alone. The results are reproduced in the accompanying figure 2B. As would be apparent from Figures 2A and 2B under dilution, the sodium and magnesium fertilizers are reduced in pH and more at very dilute concentrations. There is no difference if it is diluted with water or humectants such as sorbitol (in 1% overall solution), suggesting that humectants do not play any significant role in lowering the pH of either sodium or magnesium soap. However, in the presence of free fatty acid, surprisingly it was found that the pH drops dramatically even at less diluent (small addition of FFA). The fall in pH is higher in the case of magnesium soap as compared to sodium soap, suggesting that the presence of magnesium helps reduce the pH faster with FFA, as compared to sodium soap alone.

Example 33 In order to investigate the adaptability of various soaps for low pH formulations, different soap solutions and their respective pH in solution were studied. For this purpose, solutions of sodium stearate, potassium stearate, calcium stearate, magnesium stearate, zinc stearate and aluminum stearate were studied. The pH of the respective salt solutions was recorded under varying concentrations of up to 10%. The results are represented in figure 3 accompanying. As is evident from Figure 3, it would be evident that the pH of potassium soap is found as the highest, followed by sodium. Importantly, zinc, magnesium, calcium and aluminum showed lower pH, and it was found that they were suitable to combine with sodium and potassium salt to obtain low pH soap formulations.

Example 34 The effect of diluting the various cations in combination with selective FFA (stearic acid) to 10% solution was then studied at various proportions of the stearate to the acid. The results in terms of variation in pH are noted as shown in the accompanying figure 4. As would be apparent from FIG. 4, the dilution effect of soap, ie, sodium and potassium soap, was lower as compared to the surprising dilution effects of the other cations, ie, magnesium, calcium, zinc and aluminum. Importantly, it is further apparent from the results in Figure 4 that the selective magnesium, calcium, zinc and aluminum cations have surprisingly similar trends in pH reduction for dilution with FFA, and therefore can be advantageously combined selectively with sodium or potassium salts to obtain formulations based only on soap, of low pH. In this way, it is possible by means of the present invention to provide low pH cleaning compositions that involve only soap and that avoid the requirement of synthetic detergents to produce such low pH formulations. The selective formulation of the invention would allow to obtain formulations based only on soap, of low pH, and in the process to further achieve the advantageous benefit characteristics of soap formulations vis-à-vis their essential combinations with synthetic detergents to reduce pH as is known in the art. Importantly, the invention would on the one hand enable the desired advantageous bar properties of a soap formulation vis-à-vis synthetic detergents to be maintained, and would also facilitate the incorporation of pH-sensitive benefit agents into soap formulations, providing it a wider use / application of soap formulations.

Claims (1)

1. CLAIMS 1 . A low synergistic pH cleaning composition comprising: i) 25 to 30% soaps selected from sodium and potassium soap; ii) 30% to 80% of selected soaps of magnesium, calcium, zinc and aluminum soaps; iii) 4% to 25% water; and iv) a selective diluent which is a free fatty acid. 2. A low synergistic pH cleaning composition, as claimed in claim 1, comprising soaps with or without synthetic detergents and other additives. 3. A low synergistic pH cleaning composition as claimed in any of claims 1 or 2, comprising: i) 2% to 30% soap selected from sodium and potassium soap; ii) 30% to 80% of soap selected from magnesium, calcium, zinc and aluminum soaps; iii) 0.1% to 20% free fatty acid; and iv) 4% to 25% water. 4. A low synergistic pH cleaning composition as claimed in any of claims 1 to 3, comprising additional synthetic detergent selected from synthetic anionic, nonionic, amphoteric and zwitterionic detergents. A low synergistic pH cleaning composition as claimed in any one of claims 1 to 4, comprising other conventional additives selected from polyethylene glycol, sorbitol, glycerin and similar emollient and skin moisturizing agents, in addition to benefit agents for the skin as solar blocking agents, skin brighteners, antibacterials and other pH sensitive additives. 6. A low synergistic pH cleaning composition as claimed in any of claims 1 to 5, wherein the free fatty acid is selected from stearic acid, hysteric acid, palmitic acid, myristic acid and lauric acid and mixtures thereof. same. 7. A low synergistic pH cleaning composition as claimed in any one of claims 1 to 6, which comprises foaming surfactants / solubility in low and / or high water, with or without synthetic detergent surfactants, suds boosters as dispersants. 8. A process for the manufacture of low pH soap formulations, comprising: i) providing 2% to 30% selected soaps of sodium and potassium soap; ii) provide 30% to 80% of selected soaps of magnesium, calcium, zinc and aluminum soaps; iii) provide 4% to 25% water; and iv) providing free fatty acid as a diluent in combination with at least one of the selected soaps of sodium, potassium, magnesium, calcium, zinc and aluminum soaps. 9. A process for the manufacture of low pH soap formulations as claimed in claim 8, which comprises providing soaps with or without synthetic detergents and other additives. A process for the manufacture of the low pH soap formulation as claimed in claim 8, comprising: i) providing 2% to 30% soap selected from sodium and potassium soap; ii) provide 30% to 80% soap selected from magnesium, calcium, zinc and aluminum soaps; iii) provide 0.1% to 20% free fatty acid; and iv) provide 4% to 25% water. eleven . A process for the manufacture of the low pH soap formulation as claimed in any of claims 8 to 9, which comprises providing additional synthetic detergent selected from synthetic anionic, nonionic, amphoteric and zwitterionic detergents. 12. A process for the manufacture of the low pH soap formulation as claimed in any of claims 8 to 11, which comprises incorporating another conventional additive selected from polyethylene glycol, sorbitol, glycerin and similar emollient and skin moisturizing agents, in addition of skin benefit agents such as sunscreen agents, skin lighteners, antibacterials and other pH sensitive additives. 13. A process for the manufacture of the low pH soap formulation as claimed in any of claims 8 to 12, wherein the free fatty acids used preferably correspond to the fatty acids used to make the soaps and are from Preference, selected from stearic acid, hysteric acid, palmitic acid, myristic acid and lauric acid and mixtures thereof. 14. A low pH, synergistic soap formulation, and a process for its manufacture substantially as described and illustrated herein with references to the accompanying examples.