MXPA98008030A - Synthetic composition in a bar that comprises surfactants alcoxila - Google Patents

Abstract

The present invention is directed to specific bar-based synthetic compositions, where it has been found that relatively small amounts of specific alkoxylated nonionic surfactant increase the softness of the stick compositions without sacrificing the processability and user-desired properties, such as foam and softness from the bar

Description

SYNTHETIC COMPOSITION ON A BAR COMPRISING ALCOXYLED SURFACTANTS FIELD OF THE INVENTION The present invention relates to synthetic stick compositions (ie, sticks in which at least a significant portion of fatty acid soap has been replaced by synthetic surfactants.

BACKGROUND OF THE INVENTION Traditionally, soap has been used as a skin cleanser. Without considering its many advantages (for example, cheap, easy to manufacture in bars, has good foaming properties), soap is a very aggressive chemical compound. It often results in an irritated and cracked skin from the use of soap, especially in colder climates. To maintain cleaning effectiveness and reduce aggressiveness, the technique has used synthetic surfactants to replace some or all of the soap. In particular, anionic surfactants have been used, because these tend to mimic more clearly the generation of foam that soap readily provides. Synthetic bars and soap-based bars have significantly different processing and use properties; for example, synthetic bars often require a structuring agent or binder, while soap-based bars do not require it. Anionic surfactants, however, are still aggressive. One method of reducing the aggressiveness of anionic surfactants is to use other surfactants, such as non-ionic surfactants or other mild surfactants (for example amphoteric). The use of surfactants other than anionics, however, can introduce other problems. For example, non-ionic surfactants generally do not generate thick, creamy foam like anionics do; and both non-ionic and amphoteric surfactants for example can be sticky and introduce processing difficulties. For this reason, the technique - is always looking for materials that are softer than anionic, and / or that can be used to replace at least some of the anionic surfactants, and still, that simultaneously do not seriously compromise foam generation or the efficiency of processing. In addition, even if the anionic surfactant is not replaced, the technique is always looking for materials that can replace inert materials and / or other fillers and produce an improved softness. Unexpectedly, applicants have found that these objectives can be achieved by the inclusion of relatively low concentrations of specific nonionic surfactants in specific bar-based synthetic compositions (i.e., at least partially structured by polyalkylene glycol). That is, in a weight ratio of anionic to nonionic surfactant between 1: 1 to 10: 1, nonionic surfactants provide significantly improved softness without sacrificing processability or foam. While not wishing to be bound by theory, it is believed that non-ionic surfactants may be interacting with anionic surfactants to form a type of mixed micelles of colloidal complexes, thereby reducing the free anionic surfactant (known for its severity). the bar. The use of alkoxylated nonionic surfactants in stick compositions per se is not new. The prior art has shown that the addition of these nonionic surfactants in bars based on fatty acid soap can reduce the formation of foaming cream and reduce skin irritation by reducing the soap residue on the skin after washing in hard water. Nonionic surfactants have also been used as co-surfactants and as solvents for antibacterial agents in soap bars. They have also been used as detergents in synthetic bars in general. World Patent No. WO 9,317,088 given to Procter & Gamble, for example, describes a soap-based bar comprising 45-90% fatty acid soap, 1-8% non-ionic surfactant C14_20E? 65-? Oo as a co-active agent (EO: ethylene oxide), and 0.5-2% cationic polymer as an auxiliary of softness. World Patent No. WO 9,304,161 given to Procter & amp;; Gamble describes a soap-based bar comprising 45-90% of fatty acid soap, 0.5-10% of Ci4-2oE020-25o (preferably C? 4-20E025-8o) as a cosurfactant, and 0.5-10% of surfactant of acyl isethionate. The purpose of the addition of small amounts of alkoxylated nonionic surfactants was to reduce the formation of frothy cream. Patent No. GB 2,243,615 given to J. Dunbar, R. Bartolo, B. Redd, and A. Keegan describes a bar of antibacterial toilet soap containing 45-94% alkaline metal soap (at least 50% in phase Beta), 2-25% solvent for antibacterial agents, 0-30% synthetic detergents that are not solvents, and 0-10% fatty acid. The solvent for antibacterial agents is selected from polyethylene glycol and non-ionic alkoxylated fatty alcohols in general. Patent No. EP 311,343 given to G. Dawson and G.

Ridley describes a Beta-phase toilet soap bar comprising 45-90% alkaline-soluble soap of C8-C24 fatty acids, 0.5-45% of an alkoxylated non-ionic surfactant having an HLB of 12-19.5, and 0.01 to 5% of a water soluble polymer. The composition has an improved control of the frothy cream, with good smoothness, foaming, and transparency. Patent No. EP 363,215 given to F. Simion, R. Subramanya, R. Cantore, and D. Masucci describes an ultra-soft skin cleaning bar comprising 25-90% (preferably 65-95%) of fatty acid soap and 5-75% (preferably 5-35%) of non-ionic or alkoxylated anionic surfactants (C8Ej> 3A, A = OH or anionic main groups). It is claimed that the bar of soap is very soft and reduces the irritation of the skin by reducing the soap residue remaining after washing in hard water. Patent No. EP 213,729 given to Hight discloses a bar of soap containing 5-50% fatty acid soap, 5-25% non-ionic alkoxylated detergent as a co-active agent, and 0-10% phosphate additive. High concentrations of soap were included in the stick composition (weight ratio of fatty acid soap to ethoxylated detergents is from 1: 1 to 10: 1). Patent No. EP 287,300 given to C. Adam, G. Irlam and R. Lee discloses a bar of soap made by high energy cutting at low temperature (< 40 ° C) comprising 20-80% soap. fatty acid, 10-60% detergent which is not soap, which is selected from anionic surfactants of 8 to 18 carbon atoms and nonionic surfactants, such as alkoxylated alcohols in general. Patent No. GB 2,276,630 given to P. Powers discloses a laundry detergent bar containing 10-60% anionic detergent which is not soap (at least 10% alkylbenzene sulphonates and alkyl sulphates), 5-60% additive for detergent and 0.3-4% non-ionic alkoxylated detergent. The bar gives a reduced soft paste when it is left to stand in water. Patent No. EP 507,559 given to S. Pratley discloses a melt-molded bar comprising 25-60% of anionic, zwitterionic and nonionic surfactants (ie, non-ionic alkoxylates) in which 8-32% is soap from fatty acid. 10-50% of alcohols were also included as solvents, and 1-20% of a benefit agent for oily skin was included. U.S. Patent Nos. 3,312,626 and 3,312,627 given to D. Hooker disclose a nonionic bar composition substantially free of anionic surfactants containing 10-70% nonionic detergents, in which non-ionic alkoxylated surfactants are among the candidates. The bar also contains 0-70% PEG, EO-PO and derivatives of these compounds as structurants. To give these bars more "soap-like" characteristics, the reference contemplates the use of 10% -80% lithium soap. It is clear that the use of lithium soap is unique to the invention (column 8, lines 20-23) and that the use of other soaps or anionic compounds (other than lithium fatty acid soap) is not contemplated. WO-A-94/21778 discloses a method for manufacturing a synthetic detergent bar that includes the use of a composition comprising 10-60% of a synthetic surfactant, 10-60% of a water-soluble material having a point of fusion in the range of 40-100 ° C, and 5-50% of an insoluble material in water having a melting point in the range of 40-100 ° C.

The present invention differs from the prior art referred to above, alone or in combination, in that applicants have found that relatively low concentrations of specific alkoxylated nonionic surfactants (ie, having a specific molecular weight, a specific melting temperature ,. and a molar ratio of specific hydrophilic to hydrophobic compounds) more effectively mitigates the skin irritation of anionic surfactants from a personal wash bar comprising from 10 to 70% of a surfactant system of which at least 50% (although not more than 40% total of the total composition) is synthetic anionic surfactant). Also new to the technique, our invention incorporates these low concentrations of specific alkoxylated nonionic surfactants into specific synthetic bar compositions (ie, structured and at least partially bonded by polyalkylene glycol or polyalkylene glycol derivatives, such as EO-PO copolymer and other modified polyalkylene glycols hydrophobically) without sacrificing processability, biodegradability, and desired user properties, such as foam, softness of the stick and homogeneity.

BRIEF DESCRIPTION OF THE INVENTION The Applicants have now found that the use of relatively small amounts of non-ionic alkoxylated surfactants defined in stick compositions comprising primarily synthetic anionic surfactant systems markedly and unexpectedly improves the smoothness of these bars. More specifically, Applicants' invention relates to stick compositions comprising: (a) 10% to 70% by weight of the total composition of a system of surfactants selected from the group consisting of anionic surfactants, non-ionic surfactants (different of the specific alkoxylated nonionic surfactants defined in (c)), cationic surfactants, amphoteric surfactants and mixtures thereof; wherein the anionic surfactant comprises at least 50 %, preferably at least 60% of the surfactant system, and wherein the anionic component additionally comprises no more than 40% by weight of the total composition; (b) 20% to 85% by weight, preferably 30 to 70% of the total composition of a rod structurant, selected from the group consisting of alkylene oxide compounds having a molecular weight from about 2000 to about 25,000, preferably 3,000 to 10,000; free fatty acids of 8 to 22 carbon atoms, paraffin waxes; water soluble starches (for example maltodextrin); and alkanols of 8 to 20 carbon atoms; wherein the alkylene oxide compounds comprise at least 20%, preferably at least 40% of the structuring system, and wherein the alkylene oxide compounds additionally comprise no more than 70% by weight of the total composition; It is a criticality of this invention to include the alkylene oxide compounds in the stick composition, because the alkylene oxide compounds serve as a dispersant and solvent for the non-ionic alkoxylated surfactants of (c); (c) 3% to 35% by weight of the total composition of an alkoxylated nonionic surfactant; wherein the weight ratio of the anionic surfactant to alkoxylated nonionic surfactant is between 1: 1 to 10: 1, preferably 2: 1 to 7: 1; wherein the molar ratio of the ethylene oxide: hydrophobic component of the alkoxylated nonionic surfactant is between 7: 1 and 40: 1 (preferably between 15: 1 and 25: 1); this molar ratio range is a criticality because, above this range, the non-ionic alkoxylated surfactant is not as efficient in mitigating the skin irritation of the anionic components (see Examples 1 and 2), and they are not as biodegradable. Below this range, the alkoxylated nonionic surfactant can cause processing problems, such as stickiness during cold rolling and extrusion, and cause unwanted properties to the user, such as formation of a soft paste and reduced foam; wherein the melting temperature of the non-ionic surfactant is between 25 ° C and 85 ° C, preferably between 40 ° C and 65 ° C; wherein the molecular weight of the non-ionic surfactant is between 500 and 3000 Dalton, preferably between 1000 and 2500 Dalton. The composition may optionally comprise from 0% to 25%, preferably from 2% to 15% by weight of solvent such as ethylene oxide or propylene oxide. Description of the Figures Figure 1 shows the% of Zein dissolved by acyl isethionate / cocoamidopropyl betaine as a function of the concentration of alkoxylated nonionic surfactant. In contrast to PEG 8000, the non-ionic alkoxylated surfactants significantly reduced the% of dissolved Zein even at very low addition concentrations. Figure 2 shows that the alkoxylated nonionic surfactants claimed in the invention (especially those with a molar ratio of ethylene oxide: hydrophobic component) significantly reduce skin irritation caused by DEFI, a mixture of sodium acyl isethionate and fatty acid (defined in Table 2, Example 1).

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to synthetic bar compositions wherein most of the bar surfactant system comprises anionic surfactant; and to specific nonionic copolymers that can be used in such stick compositions to significantly improve the softness of the stick. More specifically, the stick compositions comprise: (a) 10% to 70% by weight of the total composition of a surfactant system, wherein the surfactant system comprises surfactants selected from the group consisting of anionic surfactants, non-ionic surfactants ( different from the non-ionic alkoxylated surfactants of (c)), amphoteric surfactants, cationic surfactants and mixtures thereof, wherein the anionic surfactant comprises 50% or more, preferably 60% or more, of the surfactant system, and the anionic surfactant it comprises no more than 40% of the total composition; (b) Structuring system: 20% to 85%, preferably 30% to 70% by weight of the total composition of a structurant of the bar selected from the group consisting of alkylene oxide compounds having a MW from about 2,000 to 25,000 (which may optionally include from 1% to 5% of higher molecular weight polyalkylene glycols, having a MW from 50,000 to 500,000, especially around 100,000); fatty acids of 8 to 24 carbon atoms, preferably of 12 to 24 carbon atoms; paraffin waxes; water soluble starches (for example maltodextrin); and alkanoles of 8 to 20 carbon atoms (for example cetyl alcohol); wherein the alkylene oxide compounds comprise at least 20%, preferably at least 40% of the structuring system, and wherein the alkylene oxide compounds additionally comprise no more than about 70% by weight of the total composition; It is a criticality of this invention to include the alkylene compounds in the stick composition, because the alkylene compounds serve as a dispersant and solvent for the non-ionic alkoxylated surfactants of (c); (c) Smoothness and Co-structuring Improvement Agent: 3% to 35% by weight of the total composition of an alkoxylated nonionic surfactant; wherein the ratio of anionic surfactant to alkoxylated nonionic surfactant is between 1: 1 to 10: 1, preferably 2: 1 to 7: 1; wherein the molar ratio of ethylene oxide: hydrophobic component of the alkoxylated nonionic surfactant is between 7: 1 and 40: 1 (preferably between 15: 1 and 25: 1); this molar ratio range is a criticality because, above this range, the non-ionic alkoxylated surfactant is not as efficient in mitigating the skin irritation of the anionic components (see Examples 1 and 2), and they are not as biodegradable. Below this range, the alkoxylated nonionic surfactant can cause processing problems, such as stickiness during cold rolling and extrusion, and cause unwanted properties to the user, such as formation of a soft paste and reduced foam; wherein the melting temperature of the non-ionic surfactant is between 25 ° C and 85 ° C, preferably between 40 ° C and 65 ° C; wherein the molecular weight of the non-ionic surfactant is between 500 and 3000 Dalton, preferably between 1000 and 2500 Dalton. Surfactant System The anionic detergent active agent which may be used may be aliphatic sulfonates, such as a primary alkane sulfonate (eg, 8 to 22 carbon atoms) primary alkane disulfonate (eg, 8 to 22 carbon atoms). carbon), alkene sulfonate of 8 to 22 carbon atoms, hydroxyalkane sulfonate of 8 to 32 carbon atoms or alkyl glycerol sulfonate ether (AGS); or aromatic sulfonates such as alkyl benzene sulfonate. The anionic surfactant may also be an alkyl sulfate (for example alkyl sulfate of 12 to 18 carbon atoms) or alkyl ether sulfate (including alkyl glycerol ether sulfates). Among the alkyl ether sulfates are those having the formula: RO (CH2CH20) nS03M wherein R is an alkyl to alkenyl having 8 to 18 carbon atoms, preferably 12 to 18 carbon atoms, n has an average value greater than 1.0, preferably greater than 3; and M is a solubilizing cation such as sodium, potassium, ammonium or substituted ammonium. Sodium ammonium lauryl ether sulfates are preferred. The anionic component can also be alkyl sulfosuccinates (including mono- and dialkyl sulfosuccinates, for example from 6 to 22 carbon atoms); alkyl and acyl taurates, alkyl and acyl sarcosinates, sulfoacetates, phosphates and alkyl phosphonates of 8 to 22 carbon atoms, alkyl phosphate esters and alkylsyl alkyl phosphate esters, acyl lactates, succinates and monoalkyl maleates of 8 a 22 carbon atoms, sulfoacetates, alkyl glucosides and acyl isethionates. The sulfosuccinates may be monoalkyl sulfosuccinates having the formula: R 02CCH2CH (S03M) C02M; Y amide sulfasauccinates-MEA of the formula: R4CONHCH2CH202CCH2CH (S03M) C02M wherein R4 is in the alkyl range of 8 to 22 carbon atoms, and M is a solubilizing cation. Sarcosinates are usually indicated by the formula: R'CON (CH3) CH2C02M, wherein R 'is in the alkyl range of 8 to 22 carbon atoms, and M is a solubilizing cation. Tauratos are generally identified by the formula: R2CONR3CH2CH2S03M wherein R2 is in the alkyl range of 8 to 22 carbon atoms, R3 is in the alkyl range of 1 to 4 carbon atoms, and M is a solubilizing cation. Particularly preferred are acyl acyl isethionates of 8 to 18 carbon atoms. These esters are prepared by the reaction between an alkali metal isethionate # with mixed aliphatic fatty acids having from 6 to 18 carbon atoms and an iodine value of less than 20. At least 75% of the mixed fatty acids have from 12 to 18 carbon atoms, and up to 25% have from 6 to 10 carbon atoms. Acy isethionates, when present, will generally be in the range of from about 10% to about 70% by weight of the total composition. Preferably, this component is from about 30% to about 60%. The acyl isethionate can be an alkoxylated isethionate such as described in Ilardi et al., US Patent No. 5,393,466. This compound has the general formula: OX c'-0-CH-CH2- (OCH-CH2) mS? ", M * wherein R is an alkyl group having from 8 to 18 carbon atoms, m is an integer from 1 to 4, X And they are hydrogen or an alkyl group having 1 to 4 carbon atoms, and M + is a monovalent cation such as, for example, sodium, potassium or ammonium.The anionic surfactant comprises 50% or more of the total surfactant system, but it should comprise no more than 40% by weight of the total composition.Amploteric detergents which can be used in this invention include at least one acid group.This can be a "carboxylic or sulfonic acid group." They include quaternary nitrogen, and thus Both are quaternary amido acids.They usually have to include an alkyl or alkenyl group of 7 to 18 carbon atoms.They will usually comply with a total structural formula: wherein R1 is alkyl or alkenyl of 7 to 18 carbon atoms; Rz and R3 are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 3 carbon atoms; m is 2 to 4; n is 0 to 1; X is alkylene of 1 to 3 carbon atoms, optionally substituted with hydroxyl, and Y is -C02- or -S03-. Suitable amphoteric detergents within the general formula above include simple betaines of the formula: and amido betaines of the formula Where m is 2 or 3. In both formulas R1, R2, and R3 are as previously defined. R1 can be in particular a mixture of alkyl groups of 12 and 14 carbon atoms derived from coconut, so that at least half, preferably at least three quarters of the groups R1 are preferably methyl. A further possibility is that the amphoteric detergent is a sulfobetaine of the formula. - > R "- (CH2) 3 SO3 R3 where is 2 or 3, or variants of these, in which - (CH2) 3S03 ~ is replaced by: OH-CH2 CHCH2 S03" in these formulas R1, R2, and R3 are as previously defined. The nonionic component that can be used includes in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide. either alone or with propylene oxide. The specific non-ionic detergent co u.est''t_s are the condensed materials of alkyl [of 6 to 22 carbon atoms] phenols-ethylene oxide, the condensation products of aliphatic alcohols (of 8 to 18 carbon atoms) primary or secondary, linear or branched with ethylene oxide, and products made by the condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called non-ionic detergent compounds include large chain tertiary amine oxides, large chain tertiary phosphine oxides and dialkyl sulfoxides. The nonionic component can also be a sugar amide, such as a polysaccharide amide. Specifically, the surfactant may be one of the lactobionamides described in U.S. Patent No. 5,389,279 given to Au et al .; or it can be one of the sugar amides described in the Patent .No. 5,009,814 given to Kelkenberg. Other surfactants that may be used are described in US Patent No. 3,723,325 given to Parran Jr. Nonionic and cationic surfactants that may be used include any of those described in US Patent No. 3,761,418 given to Parran Jr. Those included are the aldobionamides described in U.S. Patent No. 5,389,279 given to Au et al. and the polyhydroxy fatty acid amides described in US Patent No. 5,312,934 given to Letton. The surfactants generally comprise from 10 to 70% of the total composition except when it was noted that the anionic component comprises 50% or more of the surfactant system, and not more than 40% of the total. A preferred surfactant system is one that comprises acyl isethionate and an amphoteric component, ie betaine, as a co-surfactant. Preferably, the acyl isethionate comprises from 10% to 70%, and more preferably from 25 to 70% by weight of the surfactant composition, and the amphoteric surfactant comprises from 1% to 10% by weight of the total composition. Structuring The structurant system in the compositions of the invention is a mixture of water-soluble alkylene oxide compounds and other structurants (ie, fatty acid, maltodextrin and paraffin wax), wherein the alkylene oxide compounds comprise the less 20%, preferably at least 40% of the structuring system, and wherein the alkylene oxide compounds additionally comprise no more than about 70% by weight of the total composition. It is a critical aspect to include the alkylene oxide compounds in the stick composition, because the alkylene oxide compounds serve as a dispersant and solvent for the non-ionic alkoxylated surfactants in the compositions of the present invention. The alkylene oxide compounds include polyalkylene oxides of moderately high molecular weight, of suitable melting point (for example from 25 ° to 100 ° C, preferably from 45 ° C to 65 ° C) and in particular polyethylene glycols or mixtures of the same. The polyethylene glycols (PEG's) that are used can have a molecular weight in the range of 2,000 to 25,000, preferably 3,000 to 10,000. However, in some embodiments of this invention it is preferred to include a very small amount of polyethylene glycol with a molecular weight in the range of 50,000 to 500,000, especially molecular weights of about 100,000. It has been found that such polyethylene glycols improve the wear rate of the bars. It is believed that this is because the large chains of the polymer remain entangled even though the composition of the bar becomes wet during use.

If such high molecular weight polyethylene glycols (or any other water soluble high molecular weight polyalkylene oxide) are used, the amount is preferably from 1% to 5%, more preferably from 1% to 1.5% to 4% or 4.5 % by weight of the composition. These materials will generally be used in conjunction with a large amount of another water soluble structurant, such as the polyethylene glycol mentioned above of molecular weight 2,000 to 25,000, preferably 3,000 to 10,000. Water soluble starches (for example maltodextrin) can also be included in concentrations of 1% to 15% by weight of the total composition. Water-insoluble structurants also have a melting point in the range of 25-100 ° C, more preferably at least 45 ° C, notably 50 ° C to 90 ° C. Suitable materials that are particularly considered are fatty acids , particularly those that have a carbon chain of 12 to 24 carbon atoms. Examples are lauric, myristic, palmitic, stearic, arachidic and behenic acids and mixtures thereof. The sources of these fatty acids are coconut, primarily distilled coconut, palm, palm kernel, babassu and sebaceous fatty acids, and partially or fully hydrogenated fatty acids, or distilled fatty acids. Other suitable water-insoluble structurants include alkanols of 8 to 20 carbon atoms, particularly cetyl alcohol. These materials generally have a solubility in water of less than 5 g / liter at 20 ° C. Soaps, preferably with hydrocarbon chains greater than 14 carbon atoms (for example sodium stearate), can also be used in concentrations of about 1% to 15% by weight of the total composition. The soaps can be added without mixing, or made in situ by adding a base, for example NaOH, to convert the free fatty acids. The relative proportions of the water-soluble structurants and the water-insoluble structurants govern the rate at which the rod wears during use. The presence of the water insoluble structurant tends to retard the dissolution of the bar when exposed to water during use, and hence retards the rate of wear. The structurant is used in the bar in an amount of 20% to 85%, preferably 30% to 70% by weight, except, as noted, that the alkylene oxide compounds comprise not more than 70% by weight of the total composition. Non-ionic Surfactants Alkoxylated The non-ionic alkoxylated surfactants in the compositions of the present invention are generally commercially available polyoxyalkylene ethers of an alcohol of hydrophobic portion, wherein the hydrophobic portion can be linear or branched alkyl derivatives, aryl, alkylaryl, alkene, acyl; fatty and petroleum derivatives of alkylglycerol, glyceryl, sorbitol, lanolin oil, coconut oil, jojoba oil, castor oil, almond oil, peanut oil, wheat germ oil, rice bran oil, oil flaxseed, apricot kernel oil, walnut, palm kernel, pistachio nut, sesame seed, rape seed oil, corn oil, peach kernel oil, poppy seed oil, pine oil, oil soy, avocado oil, sunflower seed oil, hazelnut oil, olive oil, grape seed oil, safflower oil, Butyrospermum parkii seed fat, babassu oil, etc. The molar ratio of ethylene oxide: hydrophobic portion of the alkoxylated nonionic surfactant is in the range of 7: 1 to 40: 1, preferably 15: 1 to 25: 1. This molar ratio range is a critical aspect, because above this range, the alkoxylated nonionic surfactants are not as efficient to mitigate the skin irritation of the anionic surfactants (see Example 1 and Example 2), and are not as biodegradable. (Based on the public literature of Albright &; Wilson). Below this range, the nonionic surfactants can cause processing problems, such as stickiness during cold rolling and extrusion, and cause properties undesirable to the user, such as soft paste formation and reduced foam. In general, the molecular weight of the alkoxylated nonionic surfactant is between 500 and 3000 Dalton, preferably 1000 and 2500 Dalton. The molecular weight specifications provide the alkoxylated surfactants with a preferred range of melting temperature from 20 ° to 85 ° C, more preferably 40 ° to 65 ° C, the latter being more favorable for the processing and properties desired by the user (For example, the flakes are more easily formed, the pieces are extruded more quickly, and bars with adequate firmness and smoothness).

The weight ratio of anionic surfactant to alkoxylated nonionic surfactant is between 1: 1 to 10: 1, preferably 2: 1 to 7: 1. This range of weight ratio is a critical aspect because, above this range, the skin irritation of the anionic surfactants can not be effectively mitigated; below this range, the processability of the bar and the properties desired by the user, such as efficiency in foaming, can be adversely affected. Specifically, examples of various alkoxylated nonionic surfactants are set forth in Table 1 below, wherein the Tm (° C) were obtained from the literature of the suppliers, or measured by the inventors using a device for differential scanning calorimetry. (DSC).

Table 1. Non-ionic Surfactants Alkoxylated Representives Chemical Compounds Suppliers (Trademarks) Comments POE (20) cetyl ether Ni ko Chemicals (BC-20) white solid, Tm = 46.3 ° C POE (20) ICI oleyl ether (BRIJ 98) white viscous solid; Tm > 20 ° C POE (20) SEPPIC isostearate (Montanox) viscous white sorbitan solid, Tm > 25 ° C P0E (25) Nikko Chemicals cetyl ether (BC-40) white solid, Tm = 48.7 ° C P0E (32) Armak distearate (Kessco PEG 1540 solid viscous distearate) white; Tm > 20 ° C The bars of the invention may comprise 0% to 25%, preferably 2% to 15% by weight of an emollient such as ethylene glycol, propylene glycol and / or glycerin. Other Ingredients The stick compositions of this invention will usually contain water, but the amount of water is only a very small proportion of the stick. Larger amounts of water reduce the hardness of the bars. It is preferred that the amount of water is not over 15% by weight of the bars, preferably from 1% to about 10%, more preferably from 3% to 9%, more preferably from 3% to 8%. The bars of this invention may optionally include so-called benefit agents-materials included in relatively small proportions, which confer some additional benefit to the basic cleaning action of the bars. Examples of such agents are: skin conditioning agents, including emollients such as fatty alcohols and vegetable oils, essential oils, waxes, phospholipids, lanolin, antibacterial agents and disinfectants, opacifying agents, pearly-like agents, electrolytes , perfumes, sunscreen agents, fluorescent agents and coloring agents. Preferred skin conditioning agents comprise silicone oils, mineral oils and / or glycerol. The examples below are proposed - to better illustrate the invention, but are not intended to be limiting in any way. All percentages, unless noted otherwise, are proposed to be percentages by weight.

EXAMPLES Methodology Assessment of Softness The zein dissolution test was used to preliminarily investigate the irritation potential of the formulations studied. In a 256 ml (8 oz.) Container, 30 ml of an aqueous dispersion of a formulation was prepared. The dispersions were placed in a bath at 45 ° C until they were completely dissolved. When equilibrated to room temperature, 1.5 g of zein powder was added to each solution with rapid stirring for one hour. The solutions were then transferred to centrifuge tubes, and subjected to centrifugation for 30 minutes at approximately 3,000 rpms. The undissolved zein was isolated, rinsed and allowed to dry in a vacuum oven at 60 ° C at a constant weight. The percent of solubilized zein, which proportional to the irritation potential, was determined gravimetrically. The 3-Day Patch Test Protocol The patch test was used to evaluate the softness of aqueous dispersions in the skin containing 1% of DEFI active agent (sodium cocoyl isethionate) and different concentrations of the structuring / coactive agents. Patches were applied (HilltopMR Chambers, 25 mm in size) to the outer arm of the panelists under bandage-type bandages (ScanporMR tape). After each designated contact period (24 hours for the first application of the patch, 18 hours for the second and third applications), the patches were removed, and the sites were classified visually in order of severity (erythema and dryness) by trained examiners under a consistent lighting. Processing of Formulations Bar formulations were prepared in a 2-liter Patterson mixer with a sigma type paddle. The components were mixed together at ~95 ° C, and the water concentration was adjusted to approximately 8-10% by weight. The batch was covered to prevent moisture loss, and mixed for about 15 minutes. Then the cover was removed, and the mixture allowed to dry. The moisture content of the samples taken at different times during the drying step was determined by Karl Fisher titration with a turbo titrator. At the final moisture concentration (~5%), the formulation was poured onto a heated applicator roll, and flaked on a cooled roll. The scales of the cooled roller were extruded under vacuum in a Weber Seelander double refiner with a screw speed of ~ 20 rpm. The extruder nose cone was heated to 45-50 ° C. The cut pieces were stamped into bars using a Weber Seelander L4 hydraulic press with an appropriate pillow-shaped nylon nozzle. Bars were also prepared by a melt-molding process. First, the components were mixed together at 80-120 ° C in a 500 ml container, and the water concentration was adjusted to approximately 10-15% by weight. The batch was covered to prevent moisture loss, and mixed for about 15 minutes. Then the cover was removed, and the mixture allowed to dry. The moisture content of the samples taken at different times during the drying step was determined by Karl Fisher titration with a turbo titrator. At the final moisture concentration (~5%), the mixture in the vessel (in the form of a free flowing liquid) was poured into bar molds, and allowed to cool to room temperature for four hours. When solidified, the mixture was molded into the bar mold in a bar. Example 1 The components listed in Table 2 below were melted together at 80 ° C-120 ° C to produce a material that consisted predominantly of a liquid phase. All quantities are given in percentage by weight. Upon cooling to 10 ° C - 50 ° C by a cooling roller, the formulations formed plastic-like solids, which were extruded using the extrusion equipment described above (ie, the formulation processing section) and compressed into bars using the individual bar press. Also identical bar formulations were formed using the hot melt molding process. These bars contain a major active agent of DEFI and an optional co-active agent of cocoamidopropyl betaine. These bars provided a rich, creamy and unctuous foam; it was found that the cutaneous sensation of the bars was smooth and not sticky.

TABLE 2 * DEFI: directly esterified fatty acid isethionate, which is a mixture containing about 74% by weight of fatty acid isethionate, 23% of stearic-palmitic acid and small amounts of other materials, manufactured by Lever Brothers Co. , U.S. ** PEG 8000: polyoxyethylene glycol with an average molecular weight of 8000; PEG 4000: polyoxyethylene glycol with an average molecular weight of 4000.

Example 2 The components listed in Table 3 below were preferably processed using a melt-casting approach described in the methodology section. All quantities are given in percentage by weight. These bars used sodium lauryl sarcosinate (Formulation E, G) and sodium lauryl ether sulfate (Formulation F) as the main anionic detergent with optional cocoamidopropyl betaine as a coactive agent. These bars provided a rich, creamy and unctuous foam and a soft skin sensation.

TABLE 3 Example 3 The irritation reduction potential of the alkoxylated nonionic surfactants was investigated using Zein dissolution experiments. As indicated in Figure 1, the alkoxylated nonionic surfactants, as a class, are significantly more effective than PEG 8000 in reducing the% by weight of dissolved Zein by an aqueous surfactant system of DEFI / cocoamido propyl betaine (DEFI is a sodium acyl isethionate / fatty acid mixture defined in Table 2 of Example 1). The data in Figure 1 also showed that non-ionic surfactants with a molar ratio of ethylene oxide: hydrophobic component below 30: 1 are potentially better smoothness enhancers than those with higher molar ratios. Additionally, nonionic surfactants with a molar ratio below 30: 1 are more biodegradable than those with a higher molar ratio (based on the public literature of Albright &Wilson.

EXAMPLE 4 Three-day skin patch tests showed that non-ionic alkoxylated surfactants with lower ethylene oxide: hydrophobic molar ratios (< 30: 1) significantly reduced skin irritation caused by DEFI, even at low levels addition concentrations. As shown in Figure 2, in a weight ratio of sodium acyl isethionate (SAI): nonionic component of about 1: 0.37 (equivalent to 10% non-ionic alkoxylated surfactant in the Formulation bar (B) or (C) in Table 2 of Example 1), the non-ionic surfactants reduced the skin irritation of a DEFI / betaine liquor significantly. In contrast, even at a weight ratio of SAI / PEG 8000 as low as 1: 1.67 (effectively 45% of PEG 8000 in the bar of formulation D, Table 2) the PEG 8000 did not make a measurable contribution to the smoothness at aqueous liquor of SAI / CAP betaine.

Claims (11)

1. A bar composition, characterized in that it comprises: (a) 10% to 70% by weight of the total composition of a system of surfactants selected from the group consisting of anionic surfactants, non-ionic surfactants (other than the defined specific non-ionic alkoxylated surfactants) in (c)), cationic surfactants, amphoteric surfactants and mixtures thereof; wherein the anionic surfactant comprises at least 50 % of the surfactant system, and wherein the anionic component additionally comprises no more than 40% by weight of the total composition, and wherein the surfactant system comprises a mixture of anionic and amphoteric surfactants; (b) 20% to 85% by weight of the total composition of a rod structurant, selected from the group consisting of alkylene oxide compounds having a molecular weight from about 2000 to about 25,000; free fatty acids of 8 to 22 carbon atoms, paraffin waxes; water soluble starches (for example maltodextrin); and alkanols of 8 to 20 carbon atoms; wherein the alkylene oxide compounds comprise at least 20% of the structurant system, and wherein the alkylene oxide compounds additionally comprise no more than 70% by weight of the total composition (c) 3% to 35% by weight of the total composition of an alkoxylated nonionic surfactant; wherein the weight ratio of the anionic surfactant (a) to the non-ionic alkoxylated surfactant is between 1: 1 to 10: 1, wherein the molar ratio of the ethylene oxide: hydrophobic portion of the non-ionic alkoxylated surfactant is between 7: 1 and 40: 1; wherein the melting temperature of the non-ionic surfactant is between 25 ° C and 85 ° C; wherein the molecular weight of the non-ionic surfactant is between 500 and 3000 Dalton.

2. A composition according to claim 1, characterized in that the surfactant system comprises acyl isethionate and betaine.

3. A composition according to any of claim 1 or claim 2, characterized in that the structurant (b) comprises from 30% to 70% of the bar.

4. A composition according to any of the preceding claims, characterized in that the structuring system (b) contains fatty acid soap in the concentration of 1% to 15% by weight of the total composition.

5. A composition according to any of the preceding claims, characterized in that the molecular weight of the alkylene oxide compounds in (b) is from 3,000 to 10,000.

6. A composition according to any of the preceding claims, characterized in that the structuring system (b) contains at least 40% by weight of the alkylene oxide compounds.

7. A composition according to any of the preceding claims, characterized in that the melting temperature of (c) is from 40 ° C to 65 ° C.

8 A composition according to any of the preceding claims, characterized in that the molar ratio of ethylene oxide: hydrophobic portion of (c) is between 15: 1 and 25: 1.

9. A composition according to any of the preceding claims, characterized in that the weight ratio of the anionic surfactant (a) to the non-ionic alkoxylated surfactant is between 2: 1 and 7: 1.

10. A composition according to any of the preceding claims, characterized in that the molecular weight of (c) is between 1000 and 2500 Daltons.

11. A composition according to any of the preceding claims, characterized in that it additionally comprises a polyol, optionally wherein the polyol is selected from the group consisting of ethylene glycol, propylene glycol, glycerol and mixtures thereof.