DETERGENT BARS

Abstract: Synthetic detergent bar compositions comprising isethionate and polyalkylene glycol. Addition of an organic amide to such compositions has been found to assist in the prevention of phase separation.

Description: DETERGENT BARS Background of the Invention The present invention relates to bar compositions, especially synthetic soap bar compositions, which compositions comprise minimum levels of polyalkylene glycol to structure the bars. Soap is an efficient cleaning surfactant which has histori- cally been used in toilet bar compositions. Soap is harsh on the skin and therefore, for many years there has been a need to find a milder (i.e., less harsh) surfactant which can be used together with or in place of soap in such toilet bar compositions. U.S. Patent No. 4,695,395 to Caswell et al., for example, teaches a toilet bar composition comprising both soap and acyl fatty isethionate which composition is substantially milder to the skin then pure soap. In such non-soap detergent active bars, free fatty acid is generally used to structure the bars (i.e., keep them from physically falling apart) . Fatty acids, however, are not the only materials which can be used to provide bar structuring. In WO 95/12382, for example, polyalkylene glycol is taught as a preferred structurant, at least when used with aldobionamide surfactants, because the former materials provide good structuring characteristics without inhibiting lather formation. In WO 94/21778 compositions comprising 10-60% of a synthetic non-soap surfactant, fatty acid and 10-60% of a water soluble structurant having a melting point in the range of 40-100°C are disclosed. Preferred structurants for such systems are polyalkylene glycols such as polyethylene glycol. The addition of polyalkylene glycol to synthetic detergent bar compositions can introduce certain processing difficulties because polyalkylene glycols generally melt at temperatures used for mixing the components of the bars and easily phase separate. When greater than 40% of an esterified isethionate e.g. DEFI is present, this helps stabilize the polyalkylene glycol and prevents phase separation. However, it is not always desirable or economical to use such a high amount of isethionate. 1.0 Unexpectedly, applicants have found that certain organic amide compounds (i.e., generally characterized as an acyl group -CONH 2 attached to an organic group R, wherein R is hydrogen, NH 2 or substituted or unsubstituted, straight or 15 branched chain hydrocarbyl group having 1-20 carbons) , preferably a carbamide such as urea interact with such detergent compositions comprising PEG and relatively low concentrations of DEFI in such a way that phase separation is at least reduced. 20 Organic amides such as urea have been used in soap bar compositions as described in U.S. Patent No. 3,491,001 for example, to improve lathering properties. Soap bar compositions, however, do not have the phase separation 25 problems noted above associated with PEG/relatively low concentrations of DEFI bars and there is no recognition that the organic amide could be used to stop such separation and aid in bar processing. 30 German Patent 2,627,459 discloses the use of amides such as urea in compositions comprising 48.6% sodium acyl isethionate (i.e., DEFI) . This amount of DEFI is high enough to help in the phase formation of the bar such that there would not be the type of phase separation noted when PEG is added and the 35 DEFI levels are lowered (i.e., to under about 40% by wt . DEFI in the detergent bar) . Unexpectedly, applicants have found that, even in bars comprising polyalkylene glycol and under about 40% by wt . DEFI, the phase separation problem otherwise seen disappears when organic amides, such as urea, are in the composition. DEFINITION OF THE INVENTION The present invention accordingly provides a synthetic detergent bar composition comprising: (a) 10 to 60 wt% of a synthetic detergent active; (b) 10 to 60 wt% of a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) 5 to 25 wt% water-insoluble structurant having a melting point between 50 and 90°C; (d) 0.1 to 15 wt% organic amide; and (e) 1.00 to 14 wt% water; wherein component (a) comprises not more than 40 wt% isethionate based on the total composition. A second embodiment of the invention, relates to a process for making a homogeneous detergent surfactant bar which bar comprises: (a) 10 to 60 wt% of a synthetic detergent active; (b) 10 to 60 wt% of a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) 5 to 25 wt% water-insoluble structurant having a melting point between 50 and 90°C; and (d) 1 to 14 wt% water; and wherein component (a) comprises not more than 40 wt% isethionate based on the total composition and which process comprises adding the organic amide to a mixture of compounds (b) , (c) and (d) above, adding (a) the detergent active, and mixing said mixture at a temperature of 180°C to 240°C for between 10 and 180 minutes. Suitable synthetic detergent actives (a) are: alkyl ether sulphates; alkylethoxylates; alkyl glyceryl ether sulphonates; alpha olefin sulphonates; acyl taurides; methyl acyl taurates; N-acyl glutamates; acyl isethionates; anionic acyl sarcosinates; alkyl phosphates; methyl glucose esters; protein condensates; ethoxylated alkyl sulphates; alkyl polyglucosides; alkyl amine oxides; betaines; sultaines; alkyl sulphosuccinates, dialkyl sulphosuccinates, acyl lactylates and mixtures thereof. The above-mentioned detergents are preferably those based upon a C 8 to C 24 , more preferably on C 10 to C 18 , alkyl and acyl moieties. A fatty acid soap such as a sodium or potassium soap of C 12 - C 24 acid (for example stearic/palmitic mixtures) preferably in an amount of 2 to 10% wt. , more preferably 2 to 5% wt maybe present. A preferred soap is sodium stearate. Preferably, the amount of synthetic detergent active (a) may lie in the range from 10 to 50% w , more preferably 10% to 40% wt and most preferably present at not more than 35% w . A particularly preferred detergent synthetic active is acyl isethionate having the formula O R- ICI-O-CH.CH.SO.M in which R is a saturated, linear or branched alkyl group and M denotes an alkali metal or alkaline earth metal or a ine. While preferred, this compound should not be used in an amount greater than 40% wt . of the composition, preferably 10 to 40% wt. A further essential component of the invention is a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers . The polyalkylene glycol component (b) is preferably a high molecular weight polyalkylene glycol of melting point in the range 40° to 100°C and, in particular, polyethylene glycols or mixtures thereof. Preferred polyethylene glycols (PEG'S) have a molecular weight in the range 1,500-10,000. However, in some embodiments of this invention it is preferred to include a fairly small quantity of polyethylene glycol with a molecular weight in the range from 50,000 to 500,000, especially molecular weights of around 100,000. Such polyethylene glycols have been found to improve the wear rate of the bars. It is believed that this is because their long polymer chains remain entangled even when the bar composition is wetted during use. If such high molecular weight polyethylene glycols (or any other water soluble high molecular weight polyalkylene oxides) are used, the quantity is preferably from 1% to 5%, more preferably from 1.5 to 4.5% wt of the composition. These materials will generally be used jointly with a larger quantity of other water soluble structurant (b) such as the above mentioned polyethylene glycol of molecular weight 1,500 to 10, 000. Preferred polyethylene oxide polypropylene oxide block copolymers are those which melt at temperatures in the range of 40 to 100°C, such as block copolymers in which polyethylene oxide provides at least 40% by weight of the block copolymer. Such block copolymers may be used, alone or in mixtures with polyethylene glycol. Preferably, the total quantity of polyalkylene glycol is from 20% to 50% and most preferably is at least 25% wt of the composi ion. Water-insoluble structurants, component (c) , should also have a melting point in the range 25-100°C, more preferably at least 40°C to 90°C. Suitable materials which are particularly envisaged are fatty acids, particularly those having a carbon chain of 12 to 24 carbon atoms. Examples are lauric, myristic, palmitic, stearic, arachidonic and behenic acids and mixtures thereof . Sources of these fatty acids are coconut, topped coconut, palm, palm kernel, babassu and tallow fatty acids and partially or fully hardened 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 water solubility of less than 5 g/litre at 20°C. The relative proportions of the water-soluble polymer structurants component (b) and water-insoluble structurants (c) govern the rate at which the bar wears during use. The presence of the water insoluble structurant tends to delay dissolution of the bar when exposed to water during use and hence retard the rate of wear. Preferably, the composition comprises a water soluble material (e.g., starch) , more preferably a "true" water- soluble starch such as, for example, maltodextrin. By "true" water-soluble is meant lOwt % or greater solution of the starch in water will dissolve to form a clear or substantially clear solution (except for small amounts of insoluble residue which may impart a translucent haziness to otherwise clear solution) . The organic amide considered to be a processing aid should be present in an amount from about 0.1 to 15wt %, preferably 0.1 to lOwt %., more preferably 0.5 to 8wt %. Water should be present in an amount 1.0 to 14wt % of the composition. Free fatty acids with a carbon length of 8 to 22 carbon atoms are also desirably incorporated into the bar compositions. They may act as superfatting agents, skin feel and creaminess enhancers, and/or structurants. If present, the free fatty acids should preferably comprise between 1 and 15wt % of the compositions. However, they should not be present in an amount which exceeds the amount of component (b) . Other optional ingredients which may be present in the toilet bar compositions are moisturizers such as glycerin, sorbitol, ethoxylated or methoxylated ethers of methyl glucose etc; water soluble polymers such as collagens, modified cellulases (such as Polymer JR (R) ) , guar gums and polyacrylates; sequestering agents such as citrate, and emollients such as silicones, mineral oil, petrolatum, or fluorinated polyethers. In a second embodiment of the invention, the invention comprises a method for stabilizing (i.e., preventing phase separation) of a synthetic detergent bar comprising: (a) synthetic detergent active; (b) of a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) water-insoluble structurant having a melting point between 50 and 90°C; and (d) water; which process comprises adding an organic amide to a mixture comprising components (b) , (c) and (d) , adding synthetic detergent active (a) and mixing the resultant mixture at a temperature in the range 180°C to 240°C for 10 to 180 minutes The invention will now be illustrated with reference to the following non-limiting examples. EXAMPLES 1-4 Formulation having the following compositions were prepared (all percentages were percentages by wt. ) : Ingredient Compara¬ Example Example Example Example tive 1 2 3 4 Formula¬ tion PEG 8000 35 34 32 30 25 Urea -- 1 3 5 10 Na cocoyl 27.0 27.0 27.0 27.0 27.0 isethionate Palmitic- 12 12 12 12 12 stearic acid Coco 5.0 5.0 5.0 5.0 5.0 amidop opy1 betaine maltodextrin 10.0 10.0 10.0 10.0 10.0 Na stearate 5.0 5.0 5.0 5.0 5.0 Dimethicone 0.25 0.25 0.25 0.25 0.25 EHDP 0.02 0.02 0.02 0.02 0.02 EDTA 0.02 0.02 0.02 0.02 0.02 Titanium 0.5 0.5 0.5 0.5 0.5 Dioxide Fragrance 0.25 0.25 0.25 0.25 0.25 Misc. Salts 1.96 1.96 1.96 1.96 1.96 Water 6.0 6.0 6.0 6.0 6.0 It should be noted that, while in the above table all variations in urea levels were compensated for by varying the level PEG 800, this could also have been compensated for by changes in fatty acid level . The formulations were prepared as follows: In a Drais mixer, PEG and palmitic/stearic acid (ASAD) were melted. When molten, 50% NaOH (sodium hydroxide) was added to form Na stearate, and this was mixed for 10-15 minutes. Maltodextrin was then dispersed in the PEG/fatty acid premelt and cocoamidopropyl betaine was added to thicken the mixture. After about 10 minutes of mixing the remaining ingredients were added. Mixing was continued for an additional 30-60 minutes at temperatures of at least 88°C (190°F) up to 110°C (230°F) . Once at the required moisture level, the batch was removed from the mixture for further processing. In the comparative formulation (i.e., no urea), the hot material consisted of large opaque curd-like domains surrounded by an oily liquid. This "cottage cheese" appearance is termed phase separation because a clear fluid separates out from the bulk of the material. This phase separation results in inadequate mixing and processing problems further down the processing line. In the first example 1% urea was added to the PEG/fatty acid premelt (this replaced 1% PEG) . Applicants found that the "cottage cheese" appearance unexpectedly had a more homogeneous consistency with virtually no fluid separating out from the bulk material. In Example 2, 3% urea was added at the expense of PEG. This gave the hot material a homogeneous appearance with no phase separation. Examples 3 and 4 further illustrated this finding. COMPARATIVE 2 In the following example, an additional 3% fatty acid was added in place of the PEG. This was done to determine if the decrease in PEG would give the hot material a homogeneous appearance. Ingredient Comparative PEG 8000 32 Urea -- Na cocoyl isethionate 27.0 Palmitic-stearic acid 15 Coco amodipropyl betaine 5.0 Maltodextrin 10.0 Na stearate 5.0 Dimethicone 0.25 EHDP 0.02 EDTA 0.02 Titanium dioxide 0.5 Fragrance 0.25 Misc. Salts 1.96 Water 6.0 It was found that by adding additional fatty acid with no urea, no improvement in phase separation was observed. The hot material maintained the "cottage cheese" appearance. Thus, the improvement was clearly due to use of urea.

Claims: CLAIMS 1. A detergent bar composition comprising: (a) 10% to 60% by wt . of a synthetic detergent active; (b) 10% to 60% by wt. of a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) 5% to 25% water-insoluble structurant having a melting point between 50°C to 90°C; (d) 0.1% to 15% by w . organic amide; and (e) 1% to 14% by wt. water. wherein component (a) comprises not more than 40 wt% isethionate based on the total composition. 2. A composition according to claim 1, wherein the surfactant comprises a fatty acid soap. 3. A composition according to claim 2, comprising 2 to 10% fatty acid soap. 4. A composition according to claim 1 wherein b) is a polyalkylene glycol at a level within the range 25 to 50wt%. 5. A composition according to claim 1, wherein the water- insoluble structurant is a C ι: to C :4 fatty acid or a mixture thereof. 6. A composition according to claim 1, wherein the organic amide is urea. 7. A method for preventing phase separation of a detergent bar comprising: (a) synthetic detergent active; (b) a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) water-insoluble structurant having a melting point between 50 and 90°C; and (d) water; which method comprises adding an organic amide to a mixture comprising components (b) , (c) and (d) , adding detergent active (a) and mixing the resultant mixture at a temperature within the range 180°C to 240°C for 10 to 180 minutes. Use of an organic amide as a processing aid in the preparation of a synthetic detergent bar comprising (a) a synthetic detergent active; (b) a polymer selected from polyalkylene glycol and polyethylene oxide polypropylene oxide block copolymers; (c) water-insoluble structurant having a melting point between 50 and 90°C; and (d) water.

Inventors: FAIR MICHAEL JOSEPH, FARRELL TERENCE JAMES, FAIR, MICHAEL, JOSEPH, FARRELL, TERENCE, JAMES
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1996
Main classification: C11D17
IPC codes: C11D1, C11D3, C11D10, C11D17