A bar having a high water content

Abstract

The present invention relates to bar compositions. More particularly it relates to bar compositions comprising a low soap level, wherein a high water level can be incorporated. This is achieved by including a selective polymer therein. The bars of the present invention are easy to extrude and to stamp.

Description

TECHNICAL FIELD

[0001] The present invention relates to a soap bar composition. The present invention particularly relates to a fatty acid soap bar prepared by a rapid extrusion process. More particularly, it relates to a soap bar composition comprising a high water amount of about 20% to 40% water and is also easy to extrude and to emboss. It also ensures to maintain good quality soap bar properties. BACKGROUND

[0002] Surfactants have been used in personal washing applications for a long time. There are many categories of products in the personal washing market, such as body wash, facial wash, hand wash, soap bars, shampoo, etc. Products sold as body wash, facial wash and shampoo are usually in liquid form and made from synthetic anionic surfactants. They are usually sold in plastic bottles / containers. Soap bars and hand wash products usually contain soap. Soap bars do not need to be sold in plastic containers and are able to hold their own shape due to the construction in a rigid solid form. Soap bars are usually sold in cartons made from paperboard.

[0003] Soap bars are usually prepared by one of two routes. One is called the cast bar route, while the other is called the milled and pressed bar route (also known as the extruded route). The cast bar route is very well suited for the preparation of low TFM (total fatty matter) bars. TFM is defined as the total amount of fatty matter (mainly fatty acids) that can be isolated from a soap sample after decomposition with a mineral acid (usually hydrochloric acid). In cast bar soaps, the soap mixture is mixed with a polyol and poured into a cast and allowed to cool, after which the soap bar is removed from the cast. The cast bar route is able to produce at a relatively low production rate.

[0004] In the milled and pressed bar route, the soap is prepared with a high water content, then spray dried to reduce the water content and cool the soap, after which other ingredients are added, then the soap is extruded through a bar press and optionally cut and embossed to make the final soap bar. Milled and pressed soaps usually have a high TFM of 60-80 wt%.

[0005] Milled and pressed soap bars are also known as extruded soap bars. They consist of a very large number of different types of soaps. Most soap compositions comprise water insoluble soaps as well as water soluble soaps. Their structure is usually characterized by a brick and mortar type structure. The insoluble soaps, known as bricks, usually consist of longer chain C16 and C18 soaps (palmitate and stearate soaps). They are usually included in the soap bar to provide a structuring benefit, i.e. they give the soap bar its shape. The soap bar also consists of water soluble soaps, which act as the mortar, usually unsaturated C18:1 and 18:2 sodium soaps (oleic acid soaps) combined with short chain fatty acids, usually C8 to C12 or even up to C14 soaps. The water soluble soaps usually contribute to the cleansing.

[0006] In addition to about 60-80 wt% TFM, soap bars for personal washing currently made by extrusion processes contain about 14-22 wt% water. There is a need to develop sustainable technologies, one approach of which is to develop soaps with lower TFM content and by increasing the water content without compromising on cleaning efficacy. The present inventors are aware of various attempts made by the present applicant and others to reduce the fatty material content. These technologies include ways of structuring the soap bar, such as including natural silico-aluminate clays, such as bentonite or kaolin, but they are not very effective in structuring the soap bar in small amounts. If the TFM is simply replaced with higher amounts of water, problems arise during the extrusion process of the soap mass, and the extruded bar is sticky and cannot be easily imprinted.

[0007] To counteract the effects of increasing the water content, electrolytes can also be added to the soap. Electrolytes are used to "harden" the soap, which means that the hardness of the soap bar is increased and becomes less sticky. However, the addition of electrolytes provides its own set of negative attributes; for example, leading to greater degree of cracking or splitting in the extruded bar (to an unacceptable level for the consumer); and can also lead to the formation of a visible layer of electrolyte on the surface of the bar, a phenomenon known as "efflorescence".

[0008] Thus, it is very difficult to provide a predominantly fatty acid soap surfactant based bar with high content of water, which can be extruded at speeds of 200 bars per minute and higher; and at the same time not suffer from the problems of undesirable cracking and / or efflorescence (electrolyte formation) during storage of the bar.

[0009] Surprisingly, the present applicant has now found that by using a specific polymer, particularly in the presence of a controlled amount of a specific electrolyte, it is possible to provide a high extrusion, high water bar, while avoiding the problems of bar cracking and bar efflorescence, particularly on storage. Soap bars comprising polymers (e.g. acrylate polymers) are known, for example US5703026 (P&G, 1997) discloses a skin cleansing bar soap composition comprising (a) from about 40 to about 95% of a surfactant component comprising a fatty acid soap and / or a synthetic surfactant, such that the composition comprises: (i) from 0 to 95% of a fatty acid soap; and (ii) from 0% to about 50% of a synthetic surfactant; (b) from about 0.02% to about 5% of particles of an absorbent gelling material in the composition, on a dry weight basis, the absorbent gelling material having an extractable polymer content of less than about 25%; and (c) from about 5 to about 35% of water and additionally other optional ingredients.

[0010] WO 2019 / 025257 discloses a soap bar comprising soap, at least one perfume oil, at least one polymer, optionally water, and optionally other known cosmetic ingredients other than soap, perfume oil, polymer and water, wherein the at least one polymer is a water-soluble polymer, wherein the polymer has a water solubility of at least 0.01 g polymer in 100 g water at 20 °C at one or more pH values in the range of (4) to (9), and wherein the at least one polymer is selected from polymers wherein more than 20 wt% of the repeat units of the polymer are repeat units derived from at least one ethylenically unsaturated polymerizable monomer having at least one acid group, and polymers comprising repeat units derived from N-vinylpyrrolidone, wherein the proportion of these repeat units in the polymer is at least 50 wt%.

[0011] The present inventors have found that a soap bar comprising a commonly available acrylate polymer cannot provide the same good structuring properties as the specific polymers claimed in the present invention.

[0012] It is therefore an object of the present invention to provide a low TFM soap bar which can be manufactured using an extrusion route and which can be easily and conveniently embossed.

[0013] It is a further object of the present invention to provide a low TFM soap bar which, in addition to being conveniently extrudable and embossable, does not compromise bar integrity or sensory properties. SUMMARY

[0014] The present invention relates to a soap bar composition comprising

[0015] (i) 20 to 75 wt% of anhydrous soap;

[0016] (ii) a polymer comprising

[0017] (a) 39 to 59% of structural units of acrylic acid C 1-4 alkyl ester by weight of the polymer;

[0018] (b) 40 to 60% of structural units of (meth)acrylic acid by weight of the polymer;

[0019] (c) 1 to 10% of structural units of a dedicated associative monomer of formula 1 by weight of the polymer

[0020]

[0021] wherein R 1 is a linear C 10-28 alkyl group, preferably C 18-26 ;

[0022] wherein each R 2 is independently hydrogen or methyl; and

[0023] wherein n has a value ranging from 20 to 28; and

[0024] (iii) 20 to 40 wt% water. DETAILED DESCRIPTION

[0025] These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present application can be utilized in any other aspect of the present application. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the present application and are not intended to limit the application to those examples per se. Similarly, although functions, operations or steps can be described as being performed by one or more entities, this need not be the case in all implementations and, conversely, more than one entity can perform a function, operation or step described as being performed by a single entity. For example, aspects of the present application can be implemented in hardware, software, or hardware and software combined. If implemented in software, the functions, operations or steps can be performed by one or more processors, either centrally or distributed, either in a single machine or multiple machines. Also, the term "about" means that a value is within a range of 10% of the value. Numerical ranges are understood to include all values from and including the lower and higher numerical limits, respectively, even though specific values within the numerical ranges are not explicitly listed. Numerical ranges are also understood to include the range itself. For example, a range of 1 to 10 is understood to include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, etc., as well as 1 to 2, 2 to 4, 2 to 3, 4 to 6, 4 to 5, 6 to 8, 6 to 7, 8 to 9, 8 to 10, 9 to 11, etc. The value of the range is meant to be the range itself, and not a range from the lower value and to the lower value. For example, the range of 1 to 10 is meant to be the range 1 to 10, and not 1 to 2 or 2 to 10. Similarly, a range of 1 to 10 is understood to include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, etc., as well as 1 to 2, 2 to 4, 2 to 3, 4 to 6, 4 to 5, 6 to 8, 6 to 7, 8 to 9, 8 to 10, 9 to 11, etc. The value of the range is meant to be the range itself, and not a range from the lower value and to the lower value. For example, the range of 1 to 10 is meant to be the range 1 to 10, and not 1 to 2 or 2 to 10. Similarly, a range of 1 to 10 is understood to include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, etc., as well as 1 to 2, 2 to 4, 2 to 3, 4 to 6, 4 to 5, 6 to 8, 6 to 7, 8 to 9, 8 to 10, 9 to 11, etc. The value of the range is meant to be the range itself, and not a range from the lower value and to the lower value. For example, the range of 1 to 10 is meant to be the range 1 to 10, and not 1 to 2 or 2 to 10.

[0026] The present application relates to a bar composition. By bar composition is meant a cleansing composition comprising soap in a shaped solid form. The bar of the present application can be used to clean any surface, for example those used to clean clothes (e.g. laundry) or for personal cleansing. It is particularly suitable for personal cleansing. The bar of the present application comprises from 20 to 75% by weight of the bar composition of soap, preferably from 40 to 75%, more preferably from 40 to 60 wt% of soap. By the term soap is meant a salt of a fatty acid. Preferably, the soap is a C8 to C24 fatty acid soap. Preferably, the bar composition of the present application is an extruded bar.

[0027] The cation can be an alkali metal, an alkaline earth metal or an ammonium ion, preferably an alkali metal. Preferably, the cation is selected from sodium or potassium, more preferably sodium. The soap can be saturated or unsaturated. Saturated soaps are superior to unsaturated soaps in terms of stability. The oil or fatty acid can be of vegetable or animal origin.

[0028] The soap can be obtained by saponification of an oil, fat or fatty acid. The fat or oil typically used to make a bar of soap can be selected from the group consisting of beef tallow, beef tallow stearin, palm oil, palm stearin, soybean oil, fish oil, castor oil, rice bran oil, sunflower oil, coconut oil, babassu oil and palm kernel oil. The fatty acid can be from coconut, rice bran, peanut, beef tallow, palm, palm kernel, cottonseed or soybean.

[0029] Fatty acid soaps can also be prepared synthetically (e.g. by oxidation of petroleum or by hydrogenation of carbon monoxide by the Fischer-Tropsch process). Resin acids, such as those found in tall oil, can also be used. Naphthenic acids can also be used.

[0030] The bar can additionally comprise synthetic surfactants selected from one or more of the anionic, non-ionic, cationic or zwitterionic surfactant classes, preferably selected from anionic surfactants. According to the present application, the level of these synthetic surfactants in the composition is less than 8%, preferably less than 4%, more preferably less than 1%, and sometimes absent.

[0031] The compositions of the present application are in the form of shaped solids, such as bars. The cleansing soap compositions are rinse-off products which generally have a sufficient amount of surfactant contained therein such that it is used to clean a desired surface, such as a topical surface, for example the entire body, hair and scalp or face. It is applied to the topical surface and left thereon for only a few seconds or minutes and then washed off with copious amounts of water. Alternatively, it can be used to wash laundry. The bar is typically rubbed onto wet laundry, optionally scrubbed, and then rinsed with water to remove residual soap and dirt.

[0032] The bar of the present application preferably includes a low molecular weight soap (C8-C14 soap) which is generally water soluble at a level of 2-20% by weight of the composition. Preferably, the bar includes 15 to 55 wt% of a soap of a C16 to C24 fatty acid which is generally water insoluble. Also included in the total soap content of the composition can be preferably 15 to 35% of a soap of an unsaturated fatty acid. The unsaturated soap is preferably an oleic acid soap.

[0033] In a particularly preferred aspect, the bar comprises 20 to 75%, preferably 25 or 30 or 31 or 32 or 35 or 40% (at the lower end) to 70% or 65% (at the higher end) by weight of anhydrous soap. The C 16 to C 24 The saturated soap is present at 12 to 45% by weight of the total bar.

[0034] Preferably the short chain C8 to C 14 The fatty acid soap is present at 2 to 20% by weight of the total bar. It is also preferred that the C 18 The unsaturated C 18 The fatty acid soap is present at 2 to 20% by weight of the total bar. It is also preferred that the C

[0035] It is also possible to replace part of the soap with a solvent (e.g. glycerol) without compromising cleansing. This can also reduce the cost of the bar and can also bring additional benefits to the consumer such as mildness. In such bars, it is preferred that the ratio of [soap] to [water plus any water soluble solvent] (polyhydric alcohol such as glycerol or sorbitol) is from 0.5:1 to 5:1, preferably from 1:1 to 3:1. Since it is generally preferred to have less soap and more water, ratios at the lower end (1:1 to 2:1) are particularly preferred.

[0036] The novel structurant in the bar of the present application is a polymer comprising:

[0037] (a) from 39 to 59% (preferably from 44 to 58%, more preferably from 47 to 58%; most preferably from 48 to 52%) by weight of the polymer of structural units of C1-4 alkyl acrylate;

[0038] (b) from 40 to 60% (preferably from 40.5 to 55%, more preferably from 41 to 50%, most preferably from 41.5 to 45%) by weight of the polymer of (meth)acrylic acid structural units;

[0039] (c) from 1 to 10% (preferably from 2.5 to 7.5%, more preferably from 3 to 7%, most preferably from 3.5 to 6%) by weight of the polymer of structural units of a dedicated associative monomer of formula 1

[0040]

[0041] wherein R1 is a linear C10-28 alkyl group, preferably C18-26, more preferably C20-24, most preferably C11-23;

[0042] wherein each R2 is independently hydrogen or methyl, preferably at least 80 mol% of the R2 groups are methyl; more preferably wherein at least 95 mol% of the R2 groups are methyl; further more preferably wherein at least 99 mol% of the R2 groups are methyl; and

[0043] wherein n has a value in the range of from 20 to 28 (preferably from 22 to 26; more preferably from 23 to 27; most preferably from 24 to 26).

[0044] n has a value in the range of from 20 to 28 means that the average value of n lies within this range. The associative monomer of formula 1 above can be prepared by a process in which the chain length of the (OCH2CH2) group varies within a certain range but the average value of the chain length is in the range of from 20 to 28.

[0045] The most preferred polymer for use in constructing the bar of the present application comprises:

[0046] (a) from 49.7 to 51.8% by weight of the polymer of ethyl acrylate structural units;

[0047] (b) 41.5 to 43.3 wt% of (meth)acrylic structural units, wherein 95 to 100 wt% of the (meth)acrylic structural units are methacrylic structural units; and

[0048] (c) 4.5 to 4.7 wt% of structural units of a dedicated associative monomer of Formula 1

[0049]

[0050] wherein R 1 is a linear C 22 alkyl group;

[0051] wherein each R 2 is hydrogen or methyl, wherein 80 to 100 mole % of the R 2 groups are methyl; and

[0052] wherein n has a value in the range of 24 to 26.

[0053] The polymer is preferably included in the bar composition at a level of from 0.01 to 5%, more preferably from 0.05 to 3%, and most preferably from 0.1 to 2% by weight of the bar composition.

[0054] While the polymer of the present application structures the water in the soap, it is preferred that the composition include an electrolyte. While electrolytes are known to harden soap, they often result in bars that are so hard and brittle that they have excessive cracking on the surface of the bar and / or provide efflorescence (a layer of electrolyte), particularly upon storage.

[0055] The present inventors have found that the polymer as disclosed herein is particularly useful if the bar includes a specific type and amount of electrolyte. Using the electrolyte system described below, the bar can be extruded and imprinted at high speed while avoiding excessive cracking and efflorescence. The bar has a defined minimum hardness and a low tack rating.

[0056] The electrolyte according to the present application includes a compound that dissociates substantially into ions in water. The electrolyte according to the present application is not an ionic surfactant. Suitable electrolytes for inclusion in the soap making process are alkali metal salts. Preferred alkali metal salts for inclusion in the compositions of the present application include sodium sulfate, sodium chloride, sodium acetate, sodium citrate, potassium chloride, potassium sulfate, sodium carbonate and other mono- or di- or tri-salts of alkaline earth metals, more preferred electrolytes are sodium chloride, sodium sulfate, sodium citrate, potassium chloride, particularly preferred electrolytes are sodium chloride, sodium citrate or sodium sulfate, or combinations thereof. For the avoidance of doubt, it is clarified herein that the electrolyte is a non-soap material. It is particularly preferred that the soap bar composition of the present application includes an electrolyte system as defined below.

[0057] The electrolyte system is a specific combination of alkali metal chloride (in a defined amount) with a secondary electrolyte, which can be alkali metal citrate, alkali metal sulfate or a mixture of this citrate and sulfate, wherein the secondary electrolyte is also used in a specific defined amount, either alone or as a mixture. The alkali metal can be sodium or potassium, preferably sodium.

[0058] The amount of electrolyte providing this benefit is defined as follows:

[0059] 1. [Alkali metal chloride] % = 0.075 x [water] - 0.626; and

[0060] 2. [Alkali metal citrate] % = -0.0023 x [water] 2 + 0.312 x [water] - 4.34;

[0061] [Alkali metal sulfate] % = -0.0023 x [water] 2 + 0.312 x [water] - 4.34; or

[0062] [Alkali metal citrate plus alkali metal sulfate] % = -0.0023 x [water] 2 + 0.312 x [water] - 4.34,

[0063] wherein the calculated amount of electrolyte concentration is ± 15% (e.g. if the sodium chloride concentration calculated based on the formula is 0.86, it can be at a level of 0.86 ± 0.129 wt. %). The calculated amount of electrolyte concentration is preferably ± 10%, more preferably ± 5%.

[0064] The preferred amounts of electrolyte for the preferred ranges of water, based on the above formula developed by the inventors through extensive experimentation, are summarized as follows:

[0065] Water of 20 to 40 wt. % of the bar:

[0066] The sodium chloride content can be 0.74 to 2.73%, preferably 0.79 to 2.61%, most preferably 0.83 to 2.49% of the bar weight.

[0067] The sodium sulfate or sodium citrate or combination of both content can be 0.83% to 5.13%, preferably 0.88% to 4.91%, most preferably 0.93% to 4.68% of the bar weight.

[0068] Water of 20 to 35 wt. % of the bar:

[0069] The sodium chloride content can be 0.74 to 2.30%, preferably 0.79 to 2.20%, most preferably 0.83 to 2.10% of the bar weight.

[0070] The sodium sulphate or sodium citrate or combination of both can be present in an amount of 0.83% to 4.33%, preferably 0.88% to 4.14%, most preferably 0.93% to 3.95% by weight of the bar.

[0071] Water in the bar in an amount of 25 to 35 wt%:

[0072] The sodium sulphate or sodium citrate or combination of both can be present in an amount of 0.83% to 4.33%, preferably 0.88% to 4.14%, most preferably 0.93% to 3.95% by weight of the bar.

[0073] The sodium sulphate or sodium citrate or combination of both can be present in an amount of 1.72% to 4.33%, preferably 1.82% to 4.14%, most preferably 1.92% to 3.95% by weight of the bar.

[0074] The soap bar composition of the present application preferably comprises an electrolyte.

[0075] In summary, the electrolyte is preferably present in an amount of 0.1 to 8%, more preferably 0.5 to 6%, even more preferably 0.5 to 5%, further preferably 0.5 to 3%, and most preferably 1 to 3% by weight of the composition. The electrolyte is preferably included in the soap bar during the step of saponification to form the soap.

[0076] The high amount of water used in the bar of the present application is 20% to 40%, preferably 25% to 40%, preferably a lower limit of 26% by weight or 27% by weight or 28% by weight or 29% by weight or 30% by weight and an upper limit of 39% by weight or 38% by weight or 37% by weight or 36% by weight or 35% by weight, wherein any lower limit is used interchangeably with any upper limit. If such a high amount of water is used in bars known in the art previously, it usually results in a soft and tacky bar (compared to the bar of the present application which is defined by a certain minimum hardness and low tack score). Such bars known in the art previously are difficult to extrude and emboss at high extrusion rates of 200 bars / minute or higher.

[0077] Using the components (soap, polymer, electrolyte, ratio of soap to water and optional solvent) thus defined, we can obtain a bar extruded at 200 or more bars / minute and having a hardness value of 1.2 Kg to 5.0 Kg (measured at 40°C); low tack and cracking, and the bar is free of visible efflorescence.

[0078] In addition to the long, saturated soap used as structurant, the soap bar of the present application can optionally comprise 0.05% to 35% of a structurant. If desired, the use of more structurant allows for a lower ratio of [soap] to [water-soluble solvent, e.g. polyol plus water] (if desired).

[0079] The structurant can include one or more structurants such as starch, sodium carboxymethylcellulose, inorganic particulate matter (e.g., talc, calcium carbonate, zeolites, and mixtures of such particles), and mixtures thereof.C 16 To C 24 The long chain structurant and the combination of structurants described above preferably have a combined content of greater than 25%, preferably from 25% to 40%.

[0080] The composition of the present application can comprise a selected amount of zeolite in the range of 3 to 20%, preferably 5% to 15% by weight of the composition. Zeolites are hydrated aluminosilicates. Their structure consists of a three-dimensional framework of interconnected tetrahedra of A10 and Si04 coordinated by oxygen atoms. Zeolites are solids with a relatively open three-dimensional crystal structure composed of the elements aluminum, oxygen, and silicon, with an alkali or alkaline earth metal (such as sodium, potassium, or magnesium) and water molecules trapped in the interstices between them. Zeolites form a number of different crystal structures with large open pores (sometimes called cavities) that are arranged very regularly and are about the same size as small molecules.

[0081] The structural formula of a zeolite, based on its crystal unit cell (assuming both Si02 and A102 as variables), can be represented by the following formula:

[0082] M A / n (AlO2) a (SiO2) b ·wH2O

[0083] where M is a cation (e.g., sodium, potassium, or magnesium), w is the number of water molecules per unit cell, and a and b are the total number of Al and Si tetrahedra, respectively, per unit cell; and n is the valence of the metal ion. The ratio of b / a typically varies between 1 and 5.

[0084] For example, for mordenite, the chemical formula is Na8(AlO2)8(SiO2) 40

[0085] where a = 8 and b = 40; b / a is 5.

[0086] For zeolite 4A, the chemical formula is Na 96 (AlO2) 96 (SiO2) 96

[0087] where a = 96 and b = 96; b / a is 1.

[0088] Some zeolites have a b / a value that varies from 10 to 100 or even higher, for example, for ZSM-5 type zeolites.

[0089] According to the present application, the zeolite preferably used in the soap composition comprises zeolite 4A, zeolite 5A, zeolite 13A or zeolite 3A. The most preferred zeolite is zeolite 4A.

[0090] The composition of the present application preferably comprises a silicate compound, preferably sodium or calcium silicate, more preferably sodium silicate. Sodium silicate comprises a compound having the formula (Na2O) x • SiO2. The weight ratio of Na2O to SiO2may vary between 1 :2 and 1 :3.75. Sodium silicate grades with a ratio of about 1 :2 to 1 :2.85 are known as alkali silicates, while sodium silicate grades with a ratio of 1 :2.85 to about 1 :3.75 are known as neutral silicates. The form of sodium silicate that can be used includes sodium metasilicate (Na2SiO3), sodium pyrosilicate (Na6Si2O7) and sodium orthosilicate (Na4SiO4). The use of alkali sodium silicate is preferred according to the present application. Particularly preferred is alkali sodium silicate with a ratio of 1 :2. It is preferred that the soap bar comprises 0.1 to 10 wt% of sodium or calcium silicate, based on dry weight.

[0091] The soap bar composition can optionally contain some free fatty acid. When included, the free fatty acid comprises 0.1 to 15%, preferably 0.5 to 12% by weight of free fatty acid. Free fatty acid refers to a carboxylic acid comprising a hydrocarbon chain and a terminal carboxyl group bonded to H. Suitable fatty acids are C8to C22fatty acids. Preferred fatty acids are C12to C18, most preferably saturated straight chain fatty acids. However, some unsaturated fatty acids can also be used.

[0092] The composition preferably comprises a polyhydric alcohol (also known as a polyol) or mixture of polyols. Polyol is a term used herein to denote a highly water soluble compound having multiple hydroxyl groups (at least two, preferably at least three). Many types of polyol are available, including relatively low molecular weight short chain polyhydric compounds such as glycerol and propylene glycol; sugar classes such as sorbitol, mannitol, sucrose and glucose; modified carbohydrates such as hydrolysed starch, dextrin and maltodextrin, and polymeric synthetic polyols such as polyalkylene glycols, for example polyethylene glycol (PEG) and polypropylene glycol (PPG). Particularly preferred polyols are glycerol, sorbitol and mixtures thereof. The most preferred polyol is glycerol. In a preferred embodiment, the bar of the present application comprises 0 to 8%, preferably 1 to 7.5% by weight of polyol.

[0093] The soap composition can be made into bars by a process which first involves saponification of a fat feedstock with a base, followed by mixing with a polymer and water, and then extruding the mixture in a conventional bar press. The bar pieces can then be optionally cut to the desired size and stamped with the desired indicia. A particularly important benefit of the present invention is that, despite the high water content of the soap bars, it is found that the composition so prepared by extrusion is easily stamped with the desired indicia.

[0094] By "easily extruded" is meant that the bar is of sufficient hardness when extruded so that it exits the extruder in a sufficiently cohesive form which can be referred to as a rigid bar. The bar is preferably of a hardness greater than 1.2 kg, more preferably in the range of 1.2 to 5.0 kg (at 40°C). Hardness is preferably measured using a TA-XT Express apparatus available from Stable Micro Systems. This apparatus is used with a 30° conical probe - Part# P / 30c, and penetration of 15 mm is used to measure hardness. If the soap pieces are too soft and pass through the extruder, they will not be extruded from the extruder in a sufficiently cohesive piece to be referred to as a bar. By "easily stamped" is meant that the soap bar is of such consistency and sufficiently low tackiness that it does not stick to the stamp used to stamp any desired indicia on the bar. Thus, the soap bars prepared by the process of the present invention preferably include indicia stamped thereon.

[0095] The various optional ingredients which make up the final soap bar composition are described below:

[0096] Organic and inorganic adjunct materials

[0097] The total level of adjunct materials used in the bar composition should be no more than 50%, preferably 1 to 50%, more preferably 3 to 45% by weight of the soap bar composition.

[0098] Suitable starchy materials which can be used include natural starches (from corn, wheat, rice, potato, tapioca, etc.), pregelatinized starches, various physically and chemically modified starches, and mixtures thereof. The term natural starch refers to starch which has not been chemically or physically modified - also referred to as raw starch or native starch. The raw starch can be used directly in the process of making the bar composition or modified so that the starch becomes gelatinized, partially or completely.

[0099] The adjunct system can optionally include insoluble particles comprising one material or a combination of materials. By insoluble particles is meant a material which is present in the form of a solid particle and is suitable for personal washing. Preferably, there are mineral (e.g. inorganic) or organic particles present.

[0100] The insoluble particles should not be perceived as itchy or gritty, and thus the particle size should be less than 300 microns, more preferably less than 100 microns, and most preferably less than 50 microns.

[0101] Preferred inorganic particulate materials include talc and calcium carbonate. Talc is a magnesium silicate mineral material having a sheet silicate structure and a composition of Mg3Si4(OH) 22

[0102] Calcium carbonate or chalk exists in three crystalline forms: calcite, aragonite and vaterite. Calcite occurs naturally in rhombohedral or cubic form, aragonite in acicular or dendritic form and vaterite in spheroidal form.

[0103] Examples of other optional insoluble inorganic particulate materials include aluminates, silicates, phosphates, insoluble sulphates and clays (e.g. kaolin, china clay) and combinations thereof.

[0104] Organic particulate materials include: insoluble polysaccharides such as highly cross-linked or insoluble starch (e.g. by reaction with a hydrophobe such as octyl succinate) and cellulose; synthetic polymers such as various polymeric latices and suspension polymers; insoluble soaps, and mixtures thereof.

[0105] The bar composition preferably comprises from 0.1 to 25 wt%, preferably from 5 to 15 wt% of the bar composition of these minerals or organic particles.

[0106] An opacifier can optionally be present in the personal care composition. When present, the cleansing bar is typically opaque. Examples of opacifiers include titanium dioxide, zinc oxide and the like. A particularly preferred opacifier which can be used when an opaque soap composition is desired is ethylene glycol monostearate or ethylene glycol distearate, for example in the form of a 20% solution in sodium lauryl ether sulphate. An alternative opacifier is zinc stearate.

[0107] The product can be in the form of a colourless transparent bar, i.e. a transparent soap, in which case it will not contain an opacifier.

[0108] The preferred soap bars of the present application have a pH of from 8 to 11, more preferably from 9 to 11.

[0109] Preferred soap bars can additionally comprise up to 30 wt% of a benefit agent. Preferred benefit agents include moisturising agents, emollients, sunscreens and anti-ageing compounds. The benefit agent can be added at an appropriate stage in the process of making the bar. Some benefit agents can be incorporated as macrodomains.

[0110] ​Other optional ingredients such as antioxidants, fragrances, polymers, chelating agents, colorants, deodorants, dyes, enzymes, foam boosters, germicides, antimicrobials, lathering agents, pearlescent agents, skin conditioning agents, stabilizers, or super-fatting agents can be added in the method of the present application in suitable amounts. Preferably, the ingredients are added after the saponification step. Preferably, sodium metabisulfite, ethylenediaminetetraacetic acid (EDTA) or ethyleneglycolhydroxydiphosphonic acid (EHDP) are added to the formulation.

[0111] The compositions of the present application can be used to deliver an antimicrobial benefit. Preferred antimicrobial agents that include to deliver such a benefit include: oligodynamic metals or compounds thereof. Preferred metals are silver, copper, zinc, gold or aluminum. Silver is particularly preferred. In ionic form, it can be present as a salt of any applicable oxidation state or any compound. Preferred silver compounds are silver oxide, silver nitrate, silver acetate, silver sulfate, silver benzoate, silver salicylate, silver carbonate, silver citrate or silver phosphate, with silver oxide, silver sulfate and silver citrate being of particular interest in one or more embodiments. In at least one preferred embodiment, the silver compound is silver oxide. The content of the oligodynamic metal or compound thereof is preferably from 0.0001 to 2%, preferably from 0.001 to 1% by weight of the composition. Alternatively, essential oil antimicrobial actives can be included in the compositions of the present application. Preferred essential oil actives that can be included are terpineol, thymol, carvacrol, (E)-2(prop-l-enyl)phenol, 2-propylphenol, 4-pentylphenol, 4-sec-butylphenol, 2-benzylphenol, eugenol or combinations thereof. Further, preferred essential oil actives are terpineol, thymol, carvacrol or thymol, most preferably terpineol or thymol, and ideally a combination of the two. The content of the essential oil active is preferably from 0.001 to 1%, preferably from 0.01 to 0.5% by weight of the composition.

[0112] The application will now be illustrated by the following non-limiting examples.

[0113] Example

[0114] Examples A-C and 1-3: Effect of bar on bar hardness outside and inside the invention

[0115] The following six bar compositions were prepared as shown in Table-1. The hardness of each bar was measured using the following procedure:

[0116] Hardness test protocol

[0117] Principles

[0118] 30° cone probe penetrates soap / synthetic soap sample to a predetermined depth at a specified speed. The resistance generated at a particular depth is recorded. There are no size or weight requirements for the test sample except that the bar / ingot is larger than the penetration of the cone (15mm) and has sufficient area. The recorded resistance number is also related to the yield stress and the stress can be calculated as described below. Hardness (and / or calculated yield stress) can be measured by a variety of different penetrometer methods. In the present invention, as described above, we use a probe that penetrates to a depth of 15mm.

[0119] Instrumentation and equipment

[0120] TA-XT Express (Stable Micro Systems)

[0121] 30° cone probe - Part# P / 30C (Stable Micro Systems)

[0122] Sampling technique

[0123] This test can be applied to ingots from the briquetting machine, finished bars or small pieces of soap / synthetic soap ( noodles, granules or pieces). In the case of ingots, pieces of the appropriate size (9cm) for the TA-XT can be cut from larger samples. In the case of granules or pieces which are too small to fit in the TA-XT, a compression jig is used to form several noodles into a single ingot which is large enough for testing.

[0124] Procedure

[0125] Set up the TA-XT Express

[0126] These settings only need to be inserted once in the system. Whenever the instrument is opened again, they are saved and loaded. This ensures that the settings are constant and all experimental results are easily reproducible.

[0127] Set the test method

[0128] Press Menu

[0129] Select Test Settings (press 1)

[0130] Select Test TPE (press 1)

[0131] Select Option 1 (cyclic test) and press OK

[0132] Press Menu

[0133] Select Test Settings (press 1)

[0134] Select Parameters (press 2)

[0135] Select pre-test speed (press 1)

[0136] Type 2 (mm s -1 ) and press OK

[0137] Select trigger force (press 2)

[0138] Type 5 (g) and press OK

[0139] Select test speed (press 3)

[0140] Type 1 (mm s -1 ) and press OK

[0141] Select return speed (press 4)

[0142] Type 10 (mm s -1 ) and press OK

[0143] Select distance (press 5)

[0144] Type 15 (mm) for a bar of soap or 3 (mm) for a soap ingot and press OK

[0145] Select time (press 6)

[0146] Type 1 (cycle)

[0147] Calibrate

[0148] Attach the probe to the probe carrier.

[0149] Press Menu

[0150] Select option (press 3)

[0151] Select calibration force (press 1) - the instrument requires the user to check that the calibration platform is empty

[0152] Press OK to continue and wait until the instrument is ready.

[0153] Place the 2kg calibration weight on the calibration platform and press OK

[0154] Wait until the message "Calibration complete" is displayed and remove the weight from the platform.

[0155] Sample measurement

[0156] Place the blank on the test platform.

[0157] Bring the probe close to the surface of the blank (without touching it) by pressing the up or down arrows.

[0158] Press Run

[0159] Take the reading (g or kg) at the target distance (Fin).

[0160] After the run is performed, the probe returns to its initial position.

[0161] The sample is removed from the platform and its temperature recorded.

[0162] Calculation & presentation of results

[0163] Output

[0164] The output from this test is the TA-XT reading of "force" (R T ) as g or kg at the target penetration distance combined with the sample temperature measurement. (In the present invention, this force is measured in Kg at 40°C at a 15mm distance)

[0165] The force reading can be converted to tensile stress according to the following equation:

[0166] The equation to convert the TX-XT reading to tensile stress is

[0167]

[0168] Where: σ = tensile stress

[0169] C = "constraint factor" (1.5 for a 30° cone)

[0170] G c = gravitational acceleration

[0171]

[0172] d = penetration depth

[0173] q = cone angle

[0174] For a 30° cone at a 15mm penetration, equation 2 becomes

[0175] σ (Pa) = R T (g) x 128.8

[0176] This stress is equivalent to the static yield stress measured by penetrometry.

[0177] The elongation is

[0178]

[0179] Where

[0180] V = cone velocity

[0181] For a 30° cone moving at 1 mm / s,

[0182] Temperature correction

[0183] The hardness (yield stress) of skin cleansing bar formulations is temperature sensitive. In order to make meaningful comparisons, readings at the target distance (R T ) should be corrected relative to a standard reference temperature (usually 40°C) according to the following equation:

[0184] R 40 = R T x exp [a (T - 40)]

[0185] where R 40 = reading at the reference temperature (40°C)

[0186] R T = reading at temperature T

[0187] a = temperature correction factor

[0188] T = temperature at which the sample is analysed.

[0189] The correction can be applied to the extension stress.

[0190] Raw data and processed data

[0191] The final result is the temperature corrected force or stress, but it is also recommended to record the instrument reading and the sample temperature.

[0192] A hardness value of at least 1.2 Kg (measured at 40°C) is acceptable.

[0193] Table - 1:

[0194]

[0195] * The fatty mixture from which the soaps are prepared is 80% non-laurate and 20% laurate of vegetable origin

[0196] The data in the above table show that the compositions of the present application (Examples 1 to 3) provide harder soaps when using the polymers of the present application instead of the well known commercially available polyacrylate polymer (Aculyn 28) (Examples A to C) at the same corresponding water concentration.

Claims

1. A bar composition comprising: (i) 20 to 75 wt% of anhydrous soap; (ii) a polymer comprising (a) 39 to 59 % by weight of the polymer of acrylic acid C 1-4 structural units of alkyl esters of (meth)acrylic acid; (b) 40 to 60% of structural units of (meth)acrylic acid by weight of the polymer; (c) 1 to 10% of structural units of an associative monomer having Formula 1 by weight of the polymer wherein R 1 is a linear C 10-28 alkyl group; wherein each R 2 independently hydrogen or methyl; and wherein n has a value in the range of 20 to 28; (iii) 25 to 40 wt% of water; and (iv) 0.1 to 8 wt% of an electrolyte, wherein the electrolyte is a combination of an alkali metal chloride, and a secondary electrolyte selected from the group consisting of an alkali metal citrate and an alkali metal sulfate; and wherein the concentration of the alkali metal chloride, and the concentration of the alkali metal citrate, the concentration of the alkali metal sulfate are defined by the water content used as follows: 1) [alkali metal chloride] % = [0.075 x [water] - 0.626] %; and 2) [Alkali metal citrate]% = [-0.0023 × [water] 2 +0.312×[water]-4.34]% 3) [alkali metal sulfate] % = [-0.0023 x [water] + 0.312 x [water] - 4.34] %; or 2 + 0.312 x [water] - 4.34] %; or 4) [alkali metal citrate and alkali metal sulfate] = [-0.0023 x [water] 2 + 0.312 x [water] - 4.34]%, wherein the calculated amount of the concentration of the electrolyte is ± 15%.

2. The bar of claim 1, wherein the polymer comprises: (a) 49.7 to 51.8% of structural units of ethyl acrylate by weight of the polymer; (b) 41.5 to 43.3% of structural units of (meth)acrylic acid by weight of the polymer, wherein 95 to 100 wt% of the structural units of (meth)acrylic acid are structural units of methacrylic acid; and (c) 4.5 to 4.7% of structural units of an associative monomer having Formula 1 by weight of the polymer wherein R 1 is a linear C 22 alkyl group; wherein each R 2 is hydrogen or methyl, wherein 80 to 100 mole percent of the R 2 groups are methyl; and wherein n has a value in the range of 24 to 26.

3. The bar of any one of claims 1-2, further comprising 5 to 15 wt% of a zeolite.

4. The bar of any one of claims 1-2, further comprising 0.1 to 10 wt% of sodium silicate or calcium silicate.

5. A bar as claimed in any of claims 1-2 comprising from 12% to 45% of C 16 to C 24 saturated soaps by total weight of the bar.

6. The bar of any one of claims 1-2, further comprising one or more structurants selected from the group consisting of starch, carboxymethyl cellulose, or inorganic particles.

7. The bar of any one of claims 1-2, comprising 0.01 to 5% of the polymer by weight of the bar.

8. The bar of any one of claims 1-2, wherein the bar has a hardness value of 1.2 Kg to 5.0 Kg, the hardness value measured to 15 mm penetration at 40°C by a TA-XT Express instrument with a 30° conical probe - Part # P / 30c.

9. The bar of any one of claims 1-2, wherein the electrolyte comprises sodium sulfate, sodium chloride, sodium citrate, potassium chloride, potassium sulfate, or a combination thereof.

10. The bar of any one of claims 1-2, wherein the electrolyte comprises sodium chloride, sodium sulfate, sodium citrate, potassium chloride, or a combination thereof.

11. The bar of any one of claims 1-2, wherein the electrolyte is sodium chloride, sodium citrate, sodium sulfate, or a combination thereof.

12. A method of making a bar as claimed in any of claims 1 to 11 comprising the steps of: The fat charge is saponified with a base, then mixed with the polymer and water, and then the mixture is extruded in a bar press.

13. The method of claim 12, wherein the bar is easily extruded and imprinted, wherein the bar has a hardness of greater than 1.2 kg at 40°C using a TA-XT Express instrument with a 30° cone probe - Part # P / 30c to 15 mm penetration measurement.

14. The method of claim 12, wherein the bar is easily extruded and imprinted, wherein the bar has a hardness of 1.2 kg to 5.0 kg at 40°C using a TA-XT Express instrument with a 30° cone probe - Part # P / 30c to 15 mm penetration measurement.

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