WO2022122880A1

WO2022122880A1 - Soap bar composition

Info

Publication number: WO2022122880A1
Application number: PCT/EP2021/084924
Authority: WO
Inventors: ganesh khedkar; Angela Joy KOW; Darrius PILLAY; Arun M MANGAVE
Original assignee: Unilever Ip Holdings B.V.; Unilever Global Ip Limited; Conopco, Inc., D/B/A Unilever
Priority date: 2020-12-10
Filing date: 2021-12-09
Publication date: 2022-06-16
Also published as: CN116547368A; ZA202305552B

Abstract

This invention relates to a laundry composition in a solid shaped form for direct application to fabric. Although several approaches at providing laundry soap bars which are firm and have good cleaning performance while maintaining desired sensorial properties have been known, it is still desired to provide improved laundry soap bar composition with good firmness and cleaning performance when such compositions have low TFM and with minimal levels or no synthetic surfactant, while maintaining good user properties.It is thus an object of the present invention to provide a low TFM soap bar composition with higher water content in which the relatively high-water content is maintained in the finished bar composition and the bar composition is stable and suitable for consumer use.The present inventors have found that by incorporating a balanced combination of silicate structuring agent, hydroxyalkyl alkyl cellulose and fatty acid soap, it is possible to prepare a soap bar composition with lower soap content and higher water content while still maintaining satisfactory bar properties. The low TFM laundry soap bar also provides good cleaning performance.

Description

Soap bar composition

Field of the invention

This invention relates to a soap composition in a solid shaped form for direct application to fabric. More particularly, it relates to soap composition in the form of bars which are suitable for use in the handwashing of fabrics.

Background of the invention

Laundry detergent compositions designed for hand-wash markets predominantly include those in the form of powder, tablet or bars. Laundry bars designed for washing fabrics are formulated to provide effective cleaning in clothes, acceptable sudsing characteristics, slow wear rates, good hardness, durability and low smear properties.

Laundry bar compositions may include soap, synthetic detergent or a combination of soap and synthetic detergent as the main detersive surfactant. In some regions^ soapbased laundry bars are preferred for laundering fabrics. Laundry soap bar compositions typically contain 60 wt.% to 80 wt.% soaps and around 14 wt.% to 22 wt.% of water and optionally small amounts of inorganic salt and filler.

Soap is typically produced from animal and vegetable-based fats and oils as the raw materials which contain relatively high level of water associated with it. Laundry bars which incorporate soap as the sole or predominant surfactant in them typically also contain a relatively high level of water. This high levels of water in laundry soap bars makes such laundry bars soft and difficult to use.

Consumers of laundry bars generally desire a firm bar to permit the bar to be rubbed vigorously across the surface of clothes in a scrubbing action without excessively abrading the material from the surface of the bar. Soap bars employed for the purpose of laundering fabrics require to be firmer than those used for cosmetic purpose in order to effectively remove soil from fabrics during the scrubbing action using the bar. To achieve desired firmness, the laundry soap bar manufacturers dry the excess water from the soap raw material, which is costly, and often undesirable. Drying of excess water from the finished laundry bars is time consuming and costly when bars are manufactured on a large scale. As soap-based laundry compositions are typically employed in emerging world economies, reducing cost becomes a significant consideration in formulating these bars.

Typically, laundry soap bar compositions include soap at a 60 wt.% level or more to provide a suitable combination of performance, foam and firmness. Soaps are derived from triglycerides which are becoming increasing expensive. Consequently, manufacturer have sought ways to use fatty acid soaps more efficiently in soap bars.

It is particularly desirable to reduce the soap content of such compositions without altering the cleaning performance, firmness and sensorial properties. Several different technologies have been tried in the past to lower soap content in a laundry soap bar composition.

One strategy towards reducing overall soap content would be to increase the water content. However, attempts at increasing the water content in the soap bar has resulted in bars which are soft and have a sticky texture and such bar composition are extremely difficult to be processed into bars using conventional equipment. In general, increasing the water content of laundry bars has the consequence that the bars tend to shrink on storage, leading to stress cracking.

Another possible way of reducing soap content is to include fillers. However, use of soluble and insoluble fillers in the laundry bar composition may cause several adverse effects. Use of soluble fillers (eg. polyols) tends to negatively impact lather, bar hardness and increases rate of wear. On the other hand, use of insoluble fillers tends to increase the viscosity of the composition leading to processing difficulties.

When soap content is minimized, use of synthetic (e.g., anionic) surfactant is yet another way to make up for the loss in the bar user properties and lathering. One such prior art laundry soap bar is disclosed in WO 96/35772 A1 (P&G, 1996) which provides a bar composition having a combination of soap and anionic surfactant to provide desired bar firmness.

Alternately soap bar with lower soap content may be prepared by incorporating a structuring system in laundry soap bars.

One such example includes the laundry bar composition disclosed in WO 2008/071561 A1 (Unilever) which discloses a low TFM soap bar which has improved firmness. The soap bar composition includes 30 wt.% to 70 wt.% soap and a structuring system prepared by mixing soap with sodium silicate and water-soluble calcium compound to produce calcium silicate formed in-situ.

Although several approaches at providing laundry soap bars which provide desired firmness, good cleaning performance while maintaining desired sensorial properties have been known, it is still desired to provide improved laundry soap bar composition with high water content which is maintained in the finished bar composition and which also has good firmness and cleaning performance when such compositions have lower soap content and with minimal levels or no synthetic surfactant, while maintaining good user properties.

It is thus an object of the present invention to provide a soap bar composition with lower soap content and comprising low levels of or no synthetic surfactant while maintaining good user properties and bar firmness.

It is a further object of the subject invention to provide such bars with enhanced cleaning performance.

It is yet another objection of the invention to provide a soap bar composition having lower soap content and with higher water content in which the relatively high-water content is maintained in the finished bar composition and the bar composition retains its shape and integrity and is suitable for consumer use. It is also an object of the subject invention to provide a process for preparing a soap bar composition with lower soap content and with higher water levels.

It is another object of the present invention to provide for a low TFM soap bar composition which in addition to being conveniently extrudable and stamp-able does not compromise on the bar integrity and delivers the desired sensorial properties like high lather and low mush.

Summary of the invention

The present inventors have found that by incorporating a balanced combination of silicate structuring agent and a hydroxyalkyl alkyl cellulose, wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof it is possible to provide a soap bar composition with lower fatty acid soap content and higher water content while still maintaining satisfactory bar properties and sensorial properties. The soap bar composition also provides good cleaning performance, good perfume delivery and good foam performance.

According to a first aspect, present invention discloses a soap bar composition comprising: i) 15 wt.% to 60 wt.% fatty acid soap; ii) a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof; iii) a hydroxyalkyl alkyl cellulose; and, iv) 33 wt.% to 45 wt.% water.

According to the second aspect of the present invention disclosed is a process for preparing the soap bar composition of the first aspect comprising the steps of: i) neutralizing one or more fatty acid or fat with an alkaline material to obtain a fatty acid soap; ii) adding a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, hydroxyalkyl alkyl cellulose and water to the fatty acid soap formed in step (i) to form a dough mass; and, iii) converting the resulting dough mass into a shaped soap bar composition, wherein the shaped soap bar composition 15 wt.% to 60 wt.% fatty acid soap and 33 wt.% to 35 wt.% water.

Preferably the soap bar composition obtainable by the process of the second aspect is a laundry soap bar composition.

According to a third aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved bar properties.

According to another aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved cleaning performance.

According to yet another aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved fragrance performance.

By the term “bar” it is meant that the laundry composition in in the form of a shaped solid. The soap bar is in solid form which retains its shape after manufacture and during transport and storage. The term bar also includes other shaped laundry bar composition such as cake form or tablet form. The shaped solid is preferably formed either by a casting route or an extrusion route, more preferably the extrusion route. 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 invention may be utilized in any other aspect of the invention. 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 invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention

According to a first aspect of the present invention disclosed is a soap bar composition comprising 15 wt.% to 60 wt.% fatty acid soap, a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, a hydroxyalkyl alkyl cellulose, and 33 wt.% to 45 wt.% water.

Fatty acid soap

According to the first aspect of the present invention disclosed soap bar composition includes 15 wt.% to 60 wt.% fatty acid soap.

The term fatty acid soap denotes the salts of the carboxylic fatty acids. This class of compound includes ordinary alkali metal soaps such as sodium, potassium and ammonium salts of carboxylic fatty acids. Soaps can be made by direct saponification of fats and oils or by the neutralization of free fatty acids. Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil, tallow, fish oil, soya oil, e.g. sodium and potassium tallow soap. In general, sodium soaps are used in the compositions of the invention, but the soap may be also be selected from potassium, magnesium or triethanolamine soaps. The soaps useful herein are the well-known alkali metal salts of natural or synthetic aliphatic (alkanoic or alkenoic) acids having from 8 to 22 carbon atoms, preferably from 10 to 18 carbon atoms. They may be described as alkali metal carboxylates of saturated or unsaturated hydrocarbons having from 8 to 22 carbon atoms. The fatty acids may be synthetically prepared example by oxidation of petroleum stocks or by the Fischer-Tropsch process.

The fatty acid soap according to the present invention preferably includes lauric soap. The lauric soap preferably include fatty acid soap having 8 carbon atoms to 14 carbon atoms. Preferably these encompass soaps which are derived predominantly from C₈ to C12 saturated fatty acid, i.e. lauric acid, but can contain minor amounts of soaps derived from shorter chain fatty acids, e.g., Cw. Preferably lauric soaps are generally derived in practice from the hydrolysis of nut oils such as coconut oil and palm kernel oil. Lauric soap having short chain fatty acid molecules with 8 carbon atoms to 12 carbon atoms lather quickly. They are the saponification products of fatty acids or lauric oils (that is Cs to C12 palm kernel oil, coconut oil) with selected alkali (Na⁺ and/or K⁺). The lauric soaps are predominantly saturated.

The fatty acid soap may also include soaps with carbon chain length of Cu or greater. The long chain fatty acid soap molecules preferably include fatty acid soap having 14 carbon atoms to 22 carbon atoms, still preferably from 16 to 22 carbon atoms, further preferably from 16 to 20 carbon atoms. They may be classified as follows:

"Stearics" soaps which encompass soaps which are derived predominantly from C to Cis saturated fatty acid, i.e. palmitic and stearic acid but can contain minor level of saturated soaps derived from longer chain fatty acids, e.g., C20. Stearics soaps are generally derived in practice from triglyceride oils such as tallow, palm oil and palm stearin. “Oleics" soaps which encompass soaps which are derived from unsaturated fatty acids including predominantly oleic acid (Ci₈ i) , linoeleic acid( (Ci₈₂), myristoleic acid (C141) and palmitoleic acid (C161) as well as minor amounts of longer and shorter chain unsaturated and polyunsaturated fatty acids. Oleics soaps are generally derived in practice from the hydrolysis of various triglyceride oils and fats such as tallow, palm oil, sunflower seed oil and soybean oil.

Fatty acid soaps with Cu to C₂₂ carbon atoms, more preferably the saturated soaps with Cu to C₂₂ carbon atoms is insoluble in water and help maintain the structure of the bar, but the long chain fatty acid soap do not readily generate lather. Long chain fatty acid soap molecules are the saponification products (typically with sodium counterions) of primarily non-lauric oils (such as stearic and oleics) with sodium hydroxide. By non- lauric it is meant to include long saturated (Ci₆ and Ci₈) and unsaturated (Cie i , C182, C183) fatty acids found in palm oil, palm oil stearine, tallow.

Preferably the soap bar composition includes a fatty acid soap having a combination of long chain soap molecules having chain length of Cu or greater and short chain soap molecules having a chain length of Ci₂ or below. In the soap bar composition according to the present invention, preferably the ratio between the long chain soap molecules having C or greater number of carbon atoms to the short chain soap molecules having Ci₂ or lesser number of carbon atoms is from 85: 15 to 98:2, preferably the ratio is 80:20 to 98:2, still preferably from 80:20 to 90:10.

Preferably the soap bar composition according to the present invention comprises from 15 wt.% to 60 wt.% fatty acid soap. Preferably the soap bar composition comprises at least 20 wt.%, preferably at least 25 wt.%, still preferably at least 30 wt.% and most preferably at least 35 wt.%, but typically not more than 58 wt.%, still preferably not more than 55 wt.%, still further preferably not more than 53 wt.%, still more preferably not more than 50 wt.%, and most preferably not more than 45 wt.% fatty acid soap in the soap bar composition. Preferably the soap bar composition according to the present invention comprises from 15 wt.% to 50 wt.% fatty acid soap, still preferably 20 wt.% to 45 wt.% fatty acid soap and still more preferably 20 wt.% to 40 wt.% fatty acid soap. Silicate structuring agent

According to the first aspect of the present invention disclosed soap bar composition includes a silicate structuring agent. The silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof. The silicate structuring agent is preferably formed in-situ.

The silicate structuring agent is preferably pre-formed or is present by in-situ generation during the process of preparing the soap bar composition. Preferably the silicate structuring agent is an alkali metal silicate or alkaline earth metal silicate selected from calcium silicate. Preferably a further silicate structuring agent is present in the composition and selected from magnesium silicate, hydrated magnesium silicate, sodium aluminosilicate or combinations thereof. Preferably the alkali metal silicate is sodium silicate or potassium silicate. More preferably the alkali metal silicate is sodium silicate. Preferably the further silicate structuring agent is magnesium silicate. In a preferred embodiment the silicate structuring agent includes a mixture of sodium silicate and a further silicate structuring agent which is hydrated magnesium silicate.

Most preferably the silicate structuring agent is sodium silicate. Sodium silicate includes compounds having the formula (Na₂O)_xSiO₂. The weight ratio of Na₂O to SiO₂ could vary from 1 :1 .5 to 1 .3.8. Grades of sodium silicate with ratio from about 1 : 2 to 1 :2.85 are called alkaline silicate and with ratios from 1 :2.85 to about 1 .3.75 are called neutral silicate. Forms of sodium silicate that are available include sodium metasilicate (Na₂SiO₃), sodium pyrosilicate (Na₆Si₂O₇), and sodium orthosilicate (Na₄SiO₄) It is preferred as per this invention that alkaline sodium silicate is used. Especially preferred is sodium silicate with a ratio of Na₂O to SiO₂ of 1 :2. The sodium silicate is generally available as a solution in water having a solid content of 40% to 50%, the balance being water. It is preferred that the soap bar composition comprises from 0.1 wt.% to 20 wt.% sodium silicate, more preferably from 2 wt.% to 20 wt.%, still more preferably from 2 wt.% to 15 wt.%, further preferably 3 wt.% to 10 wt.% on dry weight basis.

The further silicate structuring agent may also be a magnesium silicate, preferably a hydrated magnesium silicate preferably in an amount from 0 wt.% to 10 wt.% preferably 1 wt.% to 5 wt.%, still preferably 1 wt.% to 3 wt.% in the composition. Preferably the silicate structuring agent is a mixture of sodium silicate and a further silicate structuring agent which hydrated magnesium silicate. Most preferably all the silicate structuring agent is sodium silicate.

The further silicate structuring agent may also be selected from in-situ formed borosilicate, aluminosilicate, boro-aluminosilicate or combinations thereof. The in-situ generation of borosilicate structuring agent may be prepared as discussed in WO 02/46341 A2 (Unilever, 2002). The in-situ generation of aluminosilicate may be prepared as described in GB-A-209 013 and WO 03/040283 A1 (Unilever, 2003).

Preferably the soap bar composition according to the present invention comprises from 1 wt.% to 20 wt.% silicate structuring agent. More preferably the silicate structuring agent is present in an amount ranging from 1 wt.% to 10 wt.%. Preferably the soap bar composition comprises at least 2 wt.%, preferably at least 5 wt.%, still preferably at least 8 wt.% and most preferably at least 10 wt.%, but typically not more than 25 wt.%, still preferably not more than 20 wt.%, still further preferably not more than 18 wt.%, and most preferably not more than 15 wt.% silicate structuring agent in the soap bar composition.

Hydroxyalkyl alkyl cellulose

The soap bar composition according to the first aspect of the present invention includes a hydroxyalkyl alkyl cellulose.

Cellulose consists of (3-1 ,4 glycosidically bound D-glucopyranose repeating units, designated as anhydroglucose units in the context of this invention, which are represented for unsubstituted cellulose by the formula (I)

illustrating the numbering of the carbon atoms in the anhydroglucose units. The numbering of the carbon atoms in the anhydroglucose units is referred to in order to designate the position of ether substituents covalently bound to the respective carbon atom.

Preferably the hydroxyalkyl alkyl cellulose is selected from the group consisting of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxybutyl cellulose, hydroxypropyl methyl cellulose, ethyl hydroxyethyl cellulose, hydroxymethyl butyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl butyl cellulose and mixtures thereof.

Preferably the hydroxyalkyl alkyl cellulose is a hydroxyalkyl methylcellulose. In the hydroxyalkyl methylcellulose, at least a part of the hydroxyl groups of the cellulose backbone at the 2-, 3- and 6-positions of the anhydroglucose units are substituted by a combination of methoxyl and hydroxyalkoxyl groups. The hydroxyalkoxyl groups are typically hydroxymethoxyl, hydroxyethoxyl and/or hydroxypropoxyl groups.

Hydroxyethoxyl and/or hydroxypropoxyl groups are preferred. Typically, one or two kinds of hydroxyalkoxyl groups are present in the hydroxyalkyl methylcellulose. Preferably a single kind of hydroxyalkoxyl group is present. Illustrative of the hydroxyalkyl methylcelluloses are hydroxyethyl methylcelluloses, hydroxypropyl methylcelluloses, and hydroxybutyl methylcelluloses. Most preferably, the hydroxyalkyl methylcellulose is a hydroxypropyl methylcellulose or hydroxymethyl methylcellulose. The hydroxyl groups of the cellulose backbone at the 2-, 3- and 6-positions of the anhydroglucose units are not substituted by any groups other than methoxyl and hydroxyalkoxyl groups.

Preferably the hydroxyalkyl methylcellulose used in the composition of the present invention has a specific degree of the substitution of hydroxyl groups at the 2-, 3- and 6-positions of the anhydroglucose units by methoxyl groups and hydroxyalkoxyl groups.

The average number of methoxyl groups per anhydroglucose unit is designated as the degree of substitution of methoxyl groups, DS. The degree of the substitution of hydroxyl groups at the 2-, 3- and 6-positions of the anhydroglucose units by hydroxy alkoxy I groups is expressed by the molar substitution of hydroxyalkoxyl groups, the MS. The MS is the average number of moles of hydroxyalkoxyl groups per anhydroglucose unit in the hydroxyalkyl methylcellulose. The hydroxyalkyl methylcellulose utilized in the composition of the present invention has a DS of from 1.6 to 2.7 and an MS of from 0.15 to 1.30.

Preferably the hydroxyalkyl methylcellulose has a DS of from 1.6 to 2.3, more preferably from 1.70 to 2.20. Preferably, hydroxyalkyl methylcellulose has a DS of at least 1 .7, still preferably at least 1 .8, further preferably at least 1 .85 and most preferably 1 .9, but typically not more than 2.2, still preferably not more than 2.1 and most preferably not more than 2.

Preferably the hydroxyalkyl methylcellulose has a MS of from 0.18 to 1.20, more preferably from 0.24 to 1.10. Preferably, hydroxyalkyl methylcellulose has an MS of at least, still preferably at least 0.2, further preferably at least 0.23 and most preferably 0.25, but typically not more than 1 .2, still preferably not more than 1.1 and most preferably not more than 1 .0.

Any preferred range for DS can be combined with any preferred range for MS. Most preferably the hydroxyalkyl methylcellulose has a DS of from 1 .70 to 2.20 and an MS of from 0.2 to 1.10. The sum of the DS and MS preferably is at least 2.0, more preferably at least 2.13, most preferably at least 2.14 and preferably up to 3.2, more preferably up to 3.0, most preferably up to 2.9. Some of the preferred commercially available hydroxyalkyl alkyl cellulose includes Methocel grades such as Methocel J (level of hydroxypropyl molar substitution 0.75 to 1 .00), and Methocel E (MS from 0.22 to 0.25) and K (MS from 0.18 to 0.23). Levels of methyl and hydroxypropyl substitution may be determined by the method of ASTM D 2363-72. A preferred hydroxyalkyl alkyl cellulose is the hydroxypropyl methyl cellulose having a methoxyl substitution (DSM) of 1 .92 and hydroxypropoxyl substitution (MSHP) of 0.25 and a viscosity of 4,100 mPa.s, measured as a 2% solution in water at 20°C according to ASTM D2363-79 (Reapproved 2006). The HPMC is commercially available from The Dow Chemical Company as Methocel E4M. The degree of substitution of methoxyl groups (DS) and the molar substitution of hydroxy alkoxy I groups (MS) can be determined by Zeisel cleavage of the hydroxyalkyl methylcellulose with hydrogen iodide and subsequent quantitative gas chromatographic analysis (G. Bartelmus and R. Ketterer, Z. Anal. Chem., 286 (1977) 161-190). When the hydroxyalkyl methylcellulose is hydroxypropyl methylcellulose, the determination of the % methoxyl and % hydroxypropoxyl is carried out according to the United States Pharmacopeia (USP 35, "Hypromellose", pages 3467-3469). The values obtained are % methoxyl and % hydroxypropoxyl. These are subsequently converted into degree of substitution (DS) for methoxyl substituents and molar substitution (MS) for hydroxypropoxyl substituents. Residual amounts of salt have been taken into account in the conversion.

The hydroxyalkyl methylcellulose utilized in the composition of the present invention preferably has a viscosity of from 3 to 200,000 mPa s, more preferably from 20 to 200,000 mPa s, even more preferably from 20 to 50,000 mPa s, most preferably from 20 to 15,000 mPa s, and particularly from 40 to 5,000 mPa s, measured as a 2 weight- % solution in water at 20°C. Viscosities of up to 600 mPa s are determined by Ubbelohde viscosity measurement. Viscosities above 600 mPa s are determined using a Brookfield viscometer. Descriptions on preparing the 2 wt.% HPMC solution and both Ubbelohde and Brookfield viscosity measurement conditions are described in the United States Pharmacopeia (USP 35, "Hypromellose", pages 423 — 424 and 3467- 3469 and in ASTM D-445 and ISO 3105 referenced therein).

It is also preferred that the hydroxyalkyl alkylcellulose is a hydroxyethyl methylcellulose. Cellulose derivatives having varying degrees of substitution and varying degrees of molar substitution with hydroxyethyl and methyl groups are known in the art. Reference is made to the following documents, whose disclosure is incorporated herein by reference. For example, U S. Patent No 9,051 ,218 (Kiesewetter, et al.), describes cellulose ethers including hydroxyethyl methyl cellulose (HEMC) wherein the DS of methoxy groups is in the range of 1 .2 to 2.2, preferably in the range of 1 .25 to 2.10, or in the range of 1 .4 to 2.0, and a molar substitution of hydroxylalkoxy (example, forming hydroxyethyl) in the range of 0.11 to 1.0, in the range of 0 to 0.8, or in the range of 0.14 to 0.5. HEMC polymers were prepared by reaction of wood cellulose pulp using dimethyl ether, methyl chloride, sodium hydroxide, and ethylene oxide in a two-stage reaction (Examples 1-4 of U.S. Patent No. 9,051 ,218). U S. Patent No 9,346,712 (Baumann, et al.), describes HEMC having a MS that is greater than 0.01 , 0.05 or greater, 0.1 or greater, and 0.18 or greater, and also 0.5 or less, 0.4 or less, 0.35 or less, and 0.33 or less. The HEMC is also described as having a DS greater than 1 .65, 1 .70 or greater, 1 .72 or greater, and 1 .8 or greater, and also less than 2.2, 2.0 or less, or 1 .9 or less. U S. Patent App. Pub. No. 2013/0193370 (Adden, et al.) describes cellulose ethers having a DS (methyl) of from 1.2 to 2.2, from 1.25 to 2.10, and 1.40 to 2.00, and a MS (hydroxyalkyl, e g., hydroxyethyl) of 0.11 to 1.00, 0.13 to 0.80, 0.15 to 0.70, 0.18 to 0.60, and 0.18 to 0.50. WO 2013/026657 shows exemplary HEMC and hydroxyethyl ethyl cellulose (HEEC) structures on pages 10 and 11 , respectively. DS values in the range of 1 .0 to 3, 1 .5 to 3, and 2.0 to 3 0, are described.

Preferably the hydroxyethyl methyl cellulose has a viscosity ranging from 7000 to 10,000 m Pa.s more preferably the viscosity ranging from 7400 to 9500 m Pa.s when the viscosity is measured for a 1% solution in water using a Haake Rotovisko RV 100, with a shear rate 2.55 s-1 at a temperature of 20°C. Commercially hydroxyethyl methyl cellulose is available under the tradename WALOCEL™, from the Dow Chemical Company. A preferred HEMC is Walocel™ MW 60000 PFV from the Dow Chemical Company.

Preferably the hydroxyalkyl alkyl cellulose is a hydroxyalkyl methylcellulose, preferably the hydroxyalkyl methylcellulose is selected from the group consisting of hydroxyethyl methyl cellulose, hydroxypropyl methylcellulose and mixtures thereof. Preferably the soap bar composition according to the present invention comprises from 0.1 wt.% to 5 wt.% hydroxyalkyl alkyl cellulose, preferably from 0.1 wt.% to 5 wt.% hydroxyalkyl methyl cellulose. Preferably the soap bar composition comprises at least 0.2 wt.%, preferably at least 0.25 wt.%, still preferably at least 0.3 wt.% and most preferably at least 0.5 wt.%, but typically not more than 3.5 wt.%, still preferably not more than 2 wt.%, still further preferably not more than 1 .5 wt.%, and most preferably not more than 1 wt.% hydroxyalkyl alkyl cellulose in the soap bar composition. Water

According to the first aspect, disclosed soap bar composition includes from

33 wt.% to 45 wt.% water, preferably from 34 wt.% to 45 wt.%, still preferably from 35 wt.% to 45 wt.% and further preferably from 36 wt.% to 45 wt.%. The soap bar composition of the invention is capable of stably retaining high amount of water in the range from 33 wt.% to 45 wt.%, still preferably at least 34 wt.%, further preferably at least 35 wt.%, still more preferably at least 36 wt.% furthermore preferably at least 37wt.% but the amount of water in the laundry soap bar composition is preferably not more than 40 wt.%, preferably not more than 39, still preferably not more than 38 wt.%, most preferably not more than 35 wt.%.

The preferred water content levels quoted above refers to freshly made laundry soap bars where water content is measured within 8 hours. This quantity is designated as the "initial water level" or "initial water content" of the freshly prepared laundry soap bar composition and is also known as the "nominal water content" or "nominal water level" of the composition. The water present in the bar at room temperature (approximately 25°C) includes "free" water and bound water of crystallisation.

As is well known, soap bars are subject to drying out during storage, i.e., water evaporates from the bar when the relative humidity is lower than the partial vapor pressure of water in equilibrium with the bar composition and depends on the rate of diffusion of water from the bar. Hence, depending upon how the bar is stored (type of wrapper, temperature, humidity, air circulation, etc) the actual water content of the bar at the moment of sampling can differ from the nominal water content of the bar immediately after manufacture.

Further when the fatty acid soap content in the soap bar composition is between 40 wt.% to 55 wt.% then the water content in the composition is preferably in the range from 33 to 40 wt.% by weight of the composition. Such compositions are preferred for soap bar composition used in laundry cleaning application.

Optional ingredients Laundry soap bar composition:

In addition to the components described above, the laundry soap bar composition of the present invention can contain a wide variety of optional ingredients. These optional ingredients include but are not limited to, synthetic surfactants, water soluble fillers, water-insoluble fillers, organic and inorganic adjunct materials, alkaline materials, processing aids, minor additives, dyes, electrolytes, chelating agents.

Synthetic surfactants:

Optionally the laundry soap bar composition of the present invention includes a synthetic surfactant. Preferably the synthetic surfactant is a non-soap anionic surfactant including but not limited to alkali metal and alkaline earth metal salts of higher alkyl aryl sulphonate surfactant, higher alkyl sulphate surfactant, higher fatty acid monoglyceride sulphate surfactant or mixtures thereof. Examples of mild synthetic surfactants include alkyl glyceryl ether sulfonates (AGS), anionic acyl sarcosinates, methyl acyl taurates, N-acyl glutamates, alkyl glucosides, acyl isethionates, alkyl sulfosuccinates, alkyl phosphate esters, ethoxylated alkyl phosphate esters, ethoxylated alkyl alcohols, alkyl sulfates, alkyl ether sulfates, methyl glucose esters, protein condensates, mixtures of alkyl ether sulfates and alkyl amine oxides, betaines, sultaines, and mixtures thereof. Included in the synthetic surfactants are the alkyl ether sulfates with from about 1 to about 12 ethoxy groups, especially ammonium and sodium lauryl ether sulfates. Alkyl chain lengths for these surfactants are about C₈to C22, preferably Cwto Cis.The alkyl portion of such synthetic surfactants are often derived from natural sources of fatty acids which are the same as for the fatty acid soaps.

The composition of the present invention includes less than 5 wt.%, preferably less than 3 wt.%, still preferably less than 1 wt.%, still more preferably less than 0.1 wt.% of the synthetic surfactant. Preferably the composition of the present invention is substantially free of the synthetic surfactant. By “substantially free” it is meant that there is no deliberately added synthetic surfactant in the soap bar composition of the present invention. Preferably the composition of the present invention comprises less than 5 wt.%, preferably less than 1 wt.% non-soap anionic surfactant, most preferably the soap bar composition is substantially free of the non-soap anionic surfactant. By “substantially free” it is meant that there is no deliberately added non-soap anionic surfactant in the soap bar composition of the present invention.

Soluble fillers:

Optionally the composition of the present invention includes a soluble filler. The soluble fillers consist of a polyhydric alcohol (also called polyol) or mixture of polyols. Polyol is a term used herein to designate a compound having multiple hydroxyl groups (at least two, preferably at least three) which is highly water soluble, preferably freely soluble, in water. Many types of polyols are available including but not limited to relatively low molecular weight short chain polyhydroxy compounds such as glycerol and propylene glycol; sugars such as sorbitol, mannitol, sucrose and glucose; modified carbohydrates such as hydrolyzed starch, dextrin and maltodextrin, and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG). Especially preferred polyols are glycerol, sorbitol, mannitol and their mixtures. Most preferred polyol is glycerol. Preferably the soap bar composition of the invention comprise from 0 wt.% to 8 wt.%, preferably 0.5 wt.% to 7.5 wt.%, still preferably from 1 wt.% to 7 wt.%, most preferably less than 6 wt.% soluble fillers by weight of the composition. Preferably the soap bar composition includes from 0.5 to 5 wt.% polyol, preferably glycerol.

Organic and inorganic adjunct materials:

Non limiting examples of organic adjunct material may include suitable starchy materials such as natural starch (from corn, wheat, rice, potato, tapioca and the like), pre-gelatinized starch, various physically and chemically modified starch and mixtures thereof. By the term natural starch is meant starch which has not been subjected to chemical or physical modification, also known as raw or native starch. The organic adjunct material may also be particulate materials which include insoluble polysaccharides such as crosslinked or insolubilized starch and cellulose, synthetic polymers or mixtures thereof. The composition of the present invention includes less than 5 wt.%, preferably less than 3 wt.%, still preferably less than 1 wt.%, still more preferably less than 0.1 wt.% of the organic adjunct materials. Preferably the composition of the present invention is substantially free of the water-soluble organic adjunct material. By substantially free it is meant that there is no deliberately added organic adjunct material in the soap bar composition of the present invention.

Non-limiting examples of the inorganic adjunct material includes particulate zeolite, calcite, dolomites, feldspars, silica, other carbonates, bicarbonates, and talc. Most preferred are calcium carbonate (as calcite), kaolin, silica, talc. Talc is a magnesium silicate mineral, with a sheet silicate structure and a composition Mg3Si4(OH)22 and may be available in the hydrated form. Examples of other optional insoluble inorganic particulate adjunct material includes aluminates, phosphates, insoluble sulfates, borates, sodium carbonate, calcium carbonate, magnesium sulphate, clay and combinations thereof.

The composition of the present invention includes from 0 wt.% to 12 wt.% of the inorganic adjunct material, preferably 2 wt.% to 10 wt.% of the inorganic adjunct material by weight in the laundry soap bar composition.

Alkaline material:

The alkaline material used for neutralization of the fatty acid or fats to form the fatty acid soap may be selected from a silicate, carbonate, hydroxide, alkaline aluminium- containing compounds such as aluminates phosphate and mixtures thereof. Preferably the amounts of alkaline materials used is at least equal to stoichiometric amount required for the neutralization of the precursor of soap active. For the purpose of the invention the especially preferred alkaline material used for the neutralization of the detergent active is sodium silicate, sodium hydroxide, sodium aluminate, sodium carbonate.

The composition of the present invention preferably includes a silicate compound. The silicate compound is preferably an alkali metal silicate or alkaline earth metal silicate. Preferably the alkali metal silicate is sodium silicate or potassium silicate. Preferably the alkaline earth metal silicate is calcium silicate or magnesium silicate. Most preferably the silicate compound is sodium silicate, magnesium silicate, or calcium silicate. Most preferably the silicate compound is sodium silicate. Sodium silicate includes compounds having the formula (Na₂O)_xSiO₂. The weight ratio of Na₂O to SiO₂ could vary from 1 :1 .5 to 1 .3.8. Grades of sodium silicate with ratio from about 1 : 2 to 1 :2.85 are called alkaline silicate and with ratios from 1 :2.85 to about 1 .3.75 are called neutral silicate. Forms of sodium silicate that are available include sodium metasilicate (Na₂SiO₃), sodium pyrosilicate (Na₆Si₂O₇), and sodium orthosilicate (Na₄SiO₄) It is preferred as per this invention that alkaline sodium silicate is used Especially preferred is alkaline sodium silicate with a ratio of 1 .2. It is preferred that the soap bar comprises from 0.01% to 8 wt% sodium silicate, preferably 3 wt.% to 6 wt.% on dry weight basis.

The silicate compound may also be a magnesium silicate, preferably a hydrated magnesium silicate preferably in an amount from 0 wt.% to 10 wt.% preferably 2 wt.5 to 5 wt.% in the composition.

Minor additives:

Non-limiting examples of optional minor additives which may be included in the soap bar composition of the present invention includes colorants, preservatives, perfumes, other polymers which may be incorporated up to 10 wt.% in the composition. Perfumes may be optionally present at a level of from about 0.1 wt.% to 1.5 wt.% of the composition. Any perfume known to the person skilled in the art may be used and not limiting to perfume oil, encapsulated perfume oil.

Electrolytes:

Optionally the composition of the present invention includes electrolytes. Electrolytes as per this invention include compounds that substantially dissociate into ions in water. Electrolytes as per this invention are not ionic surfactants. Suitable electrolytes for inclusion in the soap making process are alkali metal salts. Preferred alkali metal salts for inclusion in the composition of the invention 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 and especially preferred electrolyte is sodium carbonate, sodium chloride, sodium citrate or sodium sulphate or a combination thereof. For the avoidance of doubt, it is clarified that the electrolyte is a non-soap material. The composition of the present invention includes from 0.5 wt.% to 5 wt.%, preferably 0.5 wt.% to 3 wt.%, more preferably 1 wt.% to 2.5 wt.% electrolytes by weight of the composition. More preferably the composition of the present invention has less than 4.2 wt.% electrolytes, still preferably less than 3 wt.% further preferably less than 2 wt.% electrolytes, preferably wherein the electrolytes are other than sodium chloride, sodium citrate or mixtures thereof. Most preferably the composition of the present invention does not require any electrolytes.

Chelating agents:

Optionally the composition of the present invention includes a chelating agent, the chelating agents may be selected from but not limited to ethylene diamine tetra acetic acid (EDTA), ethylene hydroxy diphosphonic acid (EHDP) or mixtures thereof. The chelating agent is preferably present in an amount ranging from 0.01 wt.% to 1 wt.%. Non-phosphate chelating agents like methylglycinediacetic acid and salts thereof are also preferred.

The soap bar composition according to the present invention may preferably include less than 0.4 wt.% carboxymethyl cellulose, still preferably less than 0.3 wt.% and most preferably the composition according to the present invention includes 0 wt.% carboxymethyl cellulose and salts thereof.

The soap bar composition according to the present invention may preferably includes less than 0.5 wt.% acrylic polymers, still preferably less than 0.4 wt.% acrylic polymers, furthermore preferably less than 0.2 wt.%, still preferably less than 0.1 wt.% structuring agents like the acrylic polymers. Most preferably the composition includes 0 wt.% acrylic polymer or copolymers thereof.

Personal wash soap bar composition:

The soap bar composition according to the present invention may be a personal wash soap bar composition. In addition to the above disclosed optional ingredients the composition for personal wash soap bar composition may include an opacifier, when opacifiers are present, the soap composition in a bar form is generally opaque. Examples of opacifiers include titanium dioxide, zinc oxide and the like. A particularly preferred opacifier that can be employed when an opaque soap composition is desired is ethylene glycol mono- or di-stearate, for example in the form of a 20% solution in sodium lauryl ether sulphate. An alternative opacifying agent is zinc stearate.

The pH of preferred personal wash soap composition of the invention is from 8 to 11 , more preferably 9 to 11 .

A preferred composition may additionally include up to 30 wt.% benefit agents. Preferred benefit agents include moisturizers, emollients, sunscreens, skin lightening agents and anti-ageing compounds. The agents may be added at an appropriate step during the process of making the bars. Some benefit agents may be introduced as macro domains.

Soap bar composition

The soap bar composition according to the present invention is a low TFM soap bar composition having a high-water content. The soap bar composition retains the high- water content in the bar during storage and delivers excellent feel, hardness, cleaning and lathering properties. Preferably the soap bar composition of the present invention is prepared in the form of a bar by any conventional methods which includes frame cooling method (also known as cast bar route) or milled and plodded route (also known as extrusion route). Preferably the composition is an extruded soap bar composition with high level of water which is still easy to extrude and stamp. Preferably the soap bar composition is a laundry soap bar composition. pH:

The soap bar composition according to the present invention has a pH from 9 to 13, preferably, preferably from 9 to 11 , more preferably from 9.5 to 10.5 when measured using a 10 wt.% solution in deionised water at 25°C.

Total fatty matter:

The term “Total Fatty Matter” or TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soap without taking into account the accompanying cations. The soap bar composition according to the present invention has a TFM in the range from 15% to 60%, more preferably the TFM is in the range from 30% to 60%, further preferably 40% to 60%, still preferably from 40% to 55%.

Shape:

The laundry soap bar composition according to the present invention may take any shape. The bars according to the present invention have low rates of water loss, by which it is meant the bar typically has excellent water retention and relatively low amounts of shrinkage both upon stamping and upon storage and use.

Hardness:

The laundry soap bar composition of the present invention has a hardness expressed as Kg force required to move the probe for a prespecified distance. The hardness is measured by a Taxtmeter. The bar whose hardness is to be measured is placed onto the testing platform. Then the probe of the measuring instrument is placed close to surface of the bar composition without touching it. Next the instrument is started, and the force required to reach a preset target distance is measured and the observation is recorded. Preferably the instrument reading is from 1300 to 3000 force (R_T) in Kg at the target penetration distance of around 10 to 40.

Density:

The laundry soap bar composition according to the present invention has a density ranging from 0.8 to 1.3, preferably from 1.01 to 1.15 grams per cubic metre. One significant advantage of the present invention is that it allows for incorporation of water without significantly affecting the bar density compared to a conventional laundry soap bar composition having a higher amount of fatty acid soap.

Iodine Value:

It is preferred that the laundry soap composition according to the present invention includes soap having an Iodine Value in the range of 30 to 70, more preferably in the range of 30 to 60 and most preferably in the range of 35 to 45. The Iodine values of the composition of the present invention is measured by Wijs 20 Method, The American Oil Chemists' Society (AOCS) Official Method Cd 1-25, Revised 1988.) Iodine Value is the measure of degree of unsaturation of oils. Iodine value, also called Iodine Number is the measure of the degree of unsaturation of an oil, fat, or wax, i.e., the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax. Saturated oils, fats, and waxes take up no iodine; therefore, their iodine value is zero; but unsaturated oils, fats, and waxes take up iodine. The more iodine is attached, the higher is the iodine value.

Process for preparing the soap bar composition

According to the second aspect of the present invention disclosed is a process for preparing a soap bar composition of the first aspect comprising the steps of: i) neutralizing one or more fatty acids or fat with an alkaline material to obtain fatty acid soap; ii) adding a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, hydroxyalkyl alkyl cellulose and water to the fatty acid soap formed in step (i) to form a dough mass; iii) converting the resulting dough mass into a shaped laundry soap bar composition. wherein the shaped soap bar composition 15 wt.% to 60 wt.% fatty acid soap and 33 wt.% to 45 wt.% water.

According to another aspect disclosed is a soap bar composition obtainable by a process comprising the steps of: i) neutralizing one or more fatty acids or fat with an alkaline material to obtain fatty acid soap; ii) adding a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, hydroxyalkyl alkyl cellulose and water to the fatty acid soap formed in step (i) to form a dough mass; iii) converting the resulting dough mass into a shaped laundry soap bar composition. wherein the shaped soap bar composition 15 wt.% to 60 wt.% fatty acid soap and 33 wt.% to 45 wt.% water. The soap bar composition according to the present invention may be produced on a commercial scale by any of the processes known to a person skilled in the art. Preferably the soap bar composition of the present invention is prepared using the extrusion route. Preferably using a sigma mixer process (post dosing route) or a crutcher/Mazzonni/spray drier process.

Neutralizing fatty acid or fats to form fatty acid soap:

The fatty acids used for neutralization may be of a single type or a mixture of fatty acids. Preferably the fatty acids are a mixture of different fatty acids. The fats used are a combination of those which provide the desired amounts of short chain fatty molecules and long chain fatty molecules. In the context of the present invention, the term fats also include oils. The neutralization step is achieved by using an alkaline material preferably selected from silicate, carbonate, hydroxide, alkaline aluminium- containing material such as aluminate, a phosphate or mixtures thereof to form fatty acid soap, preferably the alkaline material is a hydroxide or silicate. Still preferably the alkaline material used for neutralization is sodium hydroxide or potassium hydroxide.

Adding silicate structuring agent:

The silicate structuring agent may be pre-formed or generated in-situ. More preferably the present invention relates to a process to prepare a soap bar composition according to the present invention comprising the step of in-situ generation of silicate structuring agent before or after the saponification step (step i). When the silicate structuring agent is calcium silicate, it is preferably generated in-situ by mixing a sparingly water-soluble calcium compound with the alkali metal silicate to form calcium silicate. The alkali metal silicate is preferably sodium silicate. The sparingly water-soluble calcium compound has a water solubility less than 2 g/litre at a temperature of 25°C. The source of calcium is preferably chosen from calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride, calcium sulphate and combinations thereof., more preferably the calcium compound is calcium hydroxide, calcium sulphate or mixtures thereof. Preferably the sparingly water-soluble calcium compound is chosen from calcium hydroxide or calcium sulphate, most preferably calcium hydroxide. Preferably the soap bar composition is obtainable by a process comprising the step of adding a silicate structuring agent wherein the silicate structuring agent is calcium silicate, and wherein the calcium silicate is generated by mixing a sparingly water-soluble calcium compound with an alkali metal silicate to form calcium silicate. The alkali metal silicate is preferably sodium silicate.

When the further silicate structuring agent is magnesium silicate, it is preferably generated in-situ by mixing a source of magnesium with the alkali metal silicate to form magnesium silicate. The alkali metal silicate is preferably sodium silicate. The sparingly water-soluble magnesium compound has a water solubility less than 2 grams /litre at a temperature of 25°C. The source of magnesium is preferably chosen from chosen from magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium chloride, magnesium sulphate and combinations thereof. Preferably the magnesium compound is magnesium sulphate. According to a preferred process, the present invention involves the step of adding a further silicate structuring agent wherein the further silicate structuring agent is magnesium silicate, and wherein the magnesium silicate is generated by mixing a source of magnesium with the alkali metal silicate to form magnesium silicate.

The silicate structuring agent may be aluminium silicate or sodium aluminium silicate. Preferably the in-situ generation of aluminium silicate structuring agent is by reacting precursor material selected from (a) soluble aluminium salt and silicate salt or (b) sodium aluminate and alkali metal silicate. It is preferably generated in-situ using a source of monomeric aluminium to condense with silicate anion. The preferable source of monomeric aluminium is aluminium sulphate and the generation of the silicate structuring agent is by reacting aluminium sulphate and alkaline sodium silicate to form sodium alumino-silicate into the formulation. The aluminosilicate structuring agent is preferably present in an amount in the range of 0.5 wt.% to 10 wt.% % by weight of the soap bar composition. According to a preferred process, the present invention involves the step of adding a further silicate structuring agent wherein the further silicate structuring agent is an aluminium silicate or sodium aluminium silicate, and wherein the aluminium silicate or sodium aluminium silicate is generated by (a) reacting soluble aluminium salt and silicate salt or (b) reacting sodium aluminate and alkali metal silicate. Crutcher process:

Step (i): This is one of the well-known process for preparing a laundry soap bar composition. In the crutcher process for preparing the soap bar composition firstly a mixture containing fatty acids or fats are taken in the crutcher maintained at a temperature of 50°C to 90°C. The oils used may be selected from distilled fatty acids or neutral oils. Next an alkali preferably sodium hydroxide or potassium hydroxide is added in an amount required for achieving complete saponification of the oils/fats. The temperature of crutcher is increased to a range from 75°C to 120°C. Preferably after the saponification, silicate structuring agent (sodium silicate, hydrated magnesium silicate), hydroxyalkyl alkyl cellulose and optional ingredients such as chelating agents, soluble fillers, inorganic fillers, adjunct materials, colorants, added water, alkaline materials (carbonates) and perfume is added to form the dough mass. Sufficient amounts of free water is added at this stage that is required to provide a final bar composition with 33 wt.% to 45 wt.% water. During the step of neutralizing the fatty acid or soap or immediately thereafter preferably a chelating agent is also added. Nonlimiting examples of the chelating agent includes the EHDP and EDTA.

Step (ii): Next step involves adding a silicate structuring agent, hydroxyalkyl alkyl cellulose and water to the fatty acid soap formed in step (i) to form a dough mass.

Preferably at this stage cationic polymer may added to the dough mass. The addition of desired cationic polymer at the end of the process avoids any complex formation with the anionic soap. Other optional ingredients that may be added to the laundry soap bar includes the electrolytes, dyes, acrylic polymer and colorants, glycerine, chelating agents, soluble fillers, inorganic fillers, alkaline materials (carbonates) are added to form a dough mass. Cationic polymer is preferably a homopolymer of dimethyldiallyl ammonium chloride. An example of a homopolymer of dimethyldiallyl ammonium chloride (DMDAAC) is that sold under the registered trademark MERQUAT by Lubrizol., Inc. Nonlimiting example includes Merquat™ 100, which is a highly charged cationic dimethyl diallyl ammonium chloride homopolymer. Commercially available example of highly preferred polyquaternium-6 polymer include, for example, that having a tradename Merquat™ 100 available from Lubrizol, has a molecular weight of about 150,000 g/mol. The laundry soap bar composition according to the present invention preferably comprises from 0.01 wt.% to 5 wt.% by weight of cationic polymer.

Drying: Preferably the dough mass is dried to reduce the moisture content of the mix to around 15 wt.% to 45 wt.%. The drying step on a commercial basis may be achieved by several different methods. One procedure employs a water-chilled roll in combination with a second feed roll to spread molten, neutralized soap into a thin, uniform layer. The cooled dough mass is then scraped from the roll to form chips and dried to a specific moisture level in a tunnel dryer. A modern technique for the drying is known as spray drying. This process directs molten dough mass to the top of a tower via spray nozzles. The dough mass sprayed to form dried soap mix hardens and then dries in the presence of a current of heated air. Vacuum may be applied to facilitate removal of water, preferably the vacuum of 50 mm Hg absolute pressure is provided. The dried soap mix is then extruded to form soap noodles having a water content of 17 wt.% to 40 wt.%. During the drying step generally 4 wt.% to 7 wt.% of the moisture is removed from the dough mass. Preferably the drier is a mazzoni vacuum spray drier which is maintained at a temperature of 85°C to 90°C and the vacuum is maintained at 700 mm Hg and the flow rate is around 3 to 8 tonnes per hour.

Plodding: Preferably after drying, the dough mass is subjected to a plodding step, the dried soap noodles are transferred to a plodder. In the plodding, the step involves converting the soap noodles into a shaped laundry soap bar composition. A conventional plodder is set up with the barrel temperature at about 90°F. (32°C.) and the nose temperature at about 110°F. (43°C.). The plodder used is a dual stage twin screw plodder that allows for a vacuum of about 40 to 65 mm Hg between the two stages. Preferably the perfume may be added at this stage. The soap log extruded from the plodder is typically round or oblong in cross-section and is cut into individual plugs. These plugs are then preferably stamped on a conventional soap stamping apparatus to yield the finished shaped laundry soap bar composition. After stamping the finished soap bar is packaged in desired packaging material which may be selected from laminate, films, paper or combinations thereof. In a preferred process, prior to plodding the dried soap noodles may be subjected to an amalgamating step carried out in a simple paddle-type mixer where the noodles are added to an amalgamator in which adjunct ingredients such as colorants, preservatives, perfume are added and mixed thoroughly to combine all the ingredients together. Further to this, the mix from the amalgamator may be preferably subjected to a milling step. In the three-roll soap mill the amalgamated mixture is passed through the rolls set at a temperature from 29°C to 41 °C to obtain a homogenous mix, This, is an intimate mixing step where the soap mix is subjected to compression and an intense shearing action. After mixing in the mill the mix is transferred to the plodder.

Sigma mixer (Post dosing') process:

Another well-known process for preparing the soap bar composition is known as the post dosing process or a sigma mixer process. The sigma mixer process involves the preparation of the soap noodles using the crutcher or a ploughshear mixer.

The step of neutralizing the fatty acid or the fat with the alkaline material is carried out in the crutcher mixer or a ploughshare mixer where the fatty acids or oils/fats with the desired levels of the fatty acid molecules with shorter chain length of C12 or below and fatty acid molecules with longer chain length of Cu or higher are added along with the alkaline material, preferably sodium hydroxide. This step is continued i.e. sodium hydroxide is added until the fatty acid or fats/oils is completely neutralised. Preferably during the neutralizing step, a desired amount of sodium carbonate or sodium chloride solution is added to the neutralizing mixture to obtain the fatty acid soap. Sufficient amounts of free water are added at this stage that is required to provide a final bar composition with 33 wt.% to 45 wt.% water. During the step of neutralizing the fatty acid or soap or immediately thereafter preferably a chelating agent is also added. Nonlimiting examples of the chelating agent includes the EHDP and EDTA.

When the saponification is over, cationic polymer, water, glycerine, chelating agents, silicate structuring agent (sodium silicate), further silicate structuring agent (hydrated magnesium silicate), hydroxyalkyl alkyl cellulose, soluble fillers, inorganic fillers, adjunct materials, colorants, alkaline materials (carbonates) are added to form a dough mass. The main parts of a typical plough share mixer are a jacketed barrel, axial rotating shaft through the centre of the barrel (longitudinally), plough-shaped blades mounted on the axial shaft, and chopper. The ploughs and the high-speed chopper are the mixing elements. While using PSM technology, the temperature of the dough mass would be kept from 90°C to 100°C. After the mixing phase, the blower is switched on which supplies ambient air for cooling the dough mass and removes the moisture. The final dried soap mix is received at 80 to 85°C. The resultant dried soap mix has a moisture content of 33 wt.% to 45 wt.% and is further processed and plodded into homogenized soap chips or noodles. The soap noodles/chips are then processed into finished shaped laundry soap bar composition.

According to a third aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 water in a laundry soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved bar properties.

According to another aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, and 33 wt.% to 45 wt.% water in a laundry soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved cleaning performance.

According to another aspect, the present invention discloses the use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, and 33 wt.% to 45 wt.% water in a laundry soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved perfume performance.

The invention will now be illustrated by means of the following non-limiting examples. Examples

Example 1

Laundry soap bar compositions according to the present invention were prepared using the formulation as shown in Table 1 . The fatty acids/fats according to the required blend was weighed and neutralized using sodium hydroxide. Thereafter hydroxyalkyl alkyl cellulose, sodium silicate and water and other ingredients as shown in the table 1 were added, and the mixture was plodded and thereafter extruded to form a shaped laundry bar composition.

Measurement of the bar parameters: a) Bar Hardness

Bar hardness refers to the hardness of the bar after manufacture which gives an indication of the processability, strength and retention of structural integrity during handling, transport and use.

Bar hardness was determined by using a TA-XT Express Texture Analyser has a 30° conical probe which penetrates into a soap bar sample at a specified speed to a predetermined depth. The resistance generated at the specified depth is recorded. The bar whose hardness is to be measured is placed onto the testing platform. Then the probe of the measuring instrument is placed close to surface of the bar composition without touching it. Next the instrument is started, and the force required to reach a preset target distance is measured and the observation is recorded (force in g, g_f). This number can be related to the yield stress (ref 2), which has long been known to be an important determinant of processability and is also related to in-use performance. The hardness of the bar was measured of the freshly prepared bars and after 24 hours of storage. b) Measurement of the pH of the laundry soap bar composition

The pH of the laundry soap bar composition was measured in a 10% solution with distilled water at 25°C. c) % rate of wear measurement: Rate of wear refers to the amount of the bar loss during use which is measured by its weight.

Step 1 : Preconditioning step

The laundry soap bar was cut into a piece with the following dimension, 8.5cm x 5 cm. A damp cloth was placed in a soap dish, the working face of the cut soap bar was placed on this soap dish touching the damp cloth and was transferred into a sealed polyethylene pouch. The soap bar was left undisturbed for 1 hour.

After an hour the soap bar placed on the soap dish was removed from the pouch and the soap dish was kept aside. A cotton cloth piece measuring 65cm x 60 cm was immersed in water with a hardness of 15 FH and after the cloth piece was fully soaked it was removed from water and the water allowed to drip out. Once no more water dripped from the cloth piece, the cloth piece was placed on a flat metal or plastic tray and the surface of the cloth was flattened and any trapped bubbles were smoothened out.

Next the laundry soap bar was removed from the soap dish and fixed to the bar holder. The working face of the laundry soap bar was now applied onto the damp cotton cloth piece resting on the plastic or a flat metal tray along the length of the damp cotton cloth (length 60 cm) by moving the holder from one edge of the cotton cloth to the other edge of the cotton cloth in each stroke. Two such strokes were applied such that the strokes were non overlapping along the length of the damp cotton cloth. This completes the preconditioning step. At this stage, the weight of the bar was measured and the weight of the bar along with the holder was recorded (Wo).

Step 2: Rate of wear evaluation

After the weight of the bar is determined, the working face of the bar is rubbed again in 5 non-overlapping strokes along the length of the damp cloth piece by moving the holder from one edge of the cloth piece to the other edge of the cloth piece covering a distance of 60 cm. After 5 strokes the weight of the bar along with the holder is measured and recorded (W). The % rate of wear is then calculated as follows:

Weight loss over 3 metres (60cm x 5 strokes) = W_o - W The average weight loss over five (5) times the effective cloth length corresponds to weight loss over three metres (3 m) for a given product - and can be expressed as weight loss per 10 metres of application to the fabric as:

Weight loss per 10 metres = weight loss over 3 metres x 10 d) Determination of the sog and mush

Sog mush refers to the ingress of water from the atmosphere into the bar and relates to the cause of sogginess of the bar.

To measure the sog mush of the prepared laundry bar composition the following process was followed.

Step 1 : preconditioning step

A cloth piece was placed in a soap basin and 10 mL water was added. Thereafter the laundry bar composition was placed in the soap basin and the soap basin along with the laundry soap bar composition was placed in a sealed pouch and left undisturbed for a period of 1 hour.

Step 2: Mush evaluation

At the end of the 1 hour the laundry soap bar composition was removed from the sealed pouch. A fresh cloth piece (measuring 40 cm x 25 cm) was taken and immersed in water to wet the cloth piece. Thereafter the cloth piece was removed and allowed to drip. The cloth piece was next placed on a flat surface and spread and smoothened on the surface. Any excess water was dabbed and removed. The preconditioned laundry soap bar composition was placed in the holder at one end of the wet cloth piece and gently pulled to the other end of the cloth piece. This procedure was repeated twice once on the top surface of the cloth piece and then on the other surface of the cloth piece. Thereafter the weight of the laundry soap bar was measured and recorded (W1). Next the laundry soap bar was again placed in the soap basin and transferred to a sealed pouch and left undisturbed for 4 hours.

Step 3: Mush evaluation

At the end of 4 hours the laundry soap bar was removed from the sealed pouch. The weight of the laundry soap bar was measured and recorded (W2, g). Next the soft mush layer on the laundry soap bar was gently scrapped across the surface of the bar and along the sides of the bar using a spatula. Now, the weight of the laundry soap bar was measured and recorded (W3) for the third time. After this the laundry soap bar was left undisturbed and any cracking of the bar is assessed visually after a day.

The sog mush was calculated using the following formula (weight in grams) Weight loss over 30cm² = [(W1 - W3)*30]/Area (40cm²)

Mush over 30cm² = [(W2 - W3)*30]/Area (40cm²) e) Measurement of the lather

Soil lather refers to foam generated during wash by which the consumer controls the product dosage.

Step 1 : preconditioning step

Step 2: lather evaluation

A white terry towel measuring 40 cm x 25 cm was immersed in water with a hardness of 15FH and when it is fully soaked, the terry towel was removed from water and allowed to drip out until no further drops come out. The terry towel was next placed on a flat metal tray and any wrinkles and bubbles were removed and the surface of the towel was smoothened.

Laundry bar was taken, and the test face of the bar was placed in the holder. The bar was moved from an edge of the towel towards the other edge of the towel such that the bar covers the entire length of the towel. This process was repeated twice. The strokes were non-overlapping.

Next 100 ml of water (15°FH hardness) was poured over the fabric and the towel was rubbed 8 times at each corner. The towel was then squeezed to remove all the water and lather out of the towel into a measuring cylinder. Another 20mL of water was added onto the towel and any lather and water remaining on the towel was scrapped and transferred into the measuring cylinder. The amount of lather generated was calculated as follows - Volume of lather (in mL) = T otal volume of water and lather - volume of water.

Leave the lather to stand for 10 minutes undisturbed and the reading of the lather volume was calculated again and recorded.

Table 1

* HEMC used in the present invention is commercially available Walocel™ MW 60000 PFV **HPMC is commercially available from The Dow Chemical Company as Methocel E4M.

The table 1 shows that the laundry soap bar composition having lower levels of the fatty acid soap shows good bar properties and lather characteristics similar to the composition having higher levels of fatty acid soap.

Example 2: Evaluation of the cleaning performance of laundry soap bar composition according to the present invention.

The cleaning performance of the soap bar composition according to the present invention (Ex 3) and a control composition (Ex C1) as shown in Table 2 was evaluated by using the Stain removal index value (SRI). SRI was measured using swatches having red curry stain, motor oil stain and black coffee stain, all of these stains are tough stains which are difficult to remove from fabrics. A FRU Precision Colorimeter WF32 was used for the measurement, the colorimeter has integrated software which measures colours in LAB scale and equipped to calculate the colour difference in CIELAB AE* which is the difference between stained sample and unstained fabric. The absolute color difference is given by the following equation,

where L is reflectance, a is redness, b is yellowness. The colour difference was calculated for both unwashed stain and washed stain using in both cases the difference between the stained area and unstained fabric before washing. From the two values obtained stain removal index (SRI) was calculated using the formulae

here, “US” refers to unwashed stain area, “WS” is washed stain area, UF is unwashed unstained fabric area, AE_(US-UF) denotes the colour difference between unwashed stain and unstained fabric, E<WS-UF) denotes the colour difference between washed stain and unstained fabric. SRI is the measure for the change in the stain intensity after washing or how effective is washing for stain removal. Index 0 means no stain removal, whereas SRI = 100 corresponds to fully removed stain. The higher the SRI value, the greater is the stain removal potential. The colorimeter was used with a light source denoted as D65 corresponding to 6500K.

For the determination of the SRI, a standard protocol was used, called the Tergometer (also called Tergotometer) wash protocol. Said Tergometer wash protocol has the following steps: 1 . Measurement of the colour of the stain on the textile cloth (unwashed stain area). 2. Switch on the Tergometer and set to a temperature of 25°C. 3. Add water of required hardness, leave to heat to 25°C for 10 minutes. 4. Add formulation to each pot and then agitate at 100 rpm for 1 minute 5. Add the stained swatches and ballast into each pot. 6. Start the wash, agitate at 100 rpm and leave to wash for 12 minutes. 7. Rinse with fresh water (24°FH) for 2 minutes. 8. Repeat rinse. 9. Dry overnight in the dark. 10. Read stains after wash.

The details of the soap bar composition that were prepared and subjected to SRI studies, thereafter, is shown in table 2.

SUBSTITUTE SHEET (RULE 26) Table 2

HEMC used in the present invention is commercially available Walocel™ MW 60000 PFV

The data given in table 2 indicates that the SRI values of compositions outside the invention (Ex C1) are lower than the SRI provided by composition inside the invention (Ex 3). Thus, it demonstrates that the composition according to the present invention having a combination of silicate structuring agent (sodium silicate) and hydroxyalkyl cellulose (HEMC) at higher levels of water and lower soap concentration gives better stain removal performance on tough to remove stains (such as fatty-oily stains like the red curry stain, motor oil stain and bleachable stains like the black coffee stain) when compared to soap bar composition with higher soap content but without the silicate structuring agent (sodium silicate) and hydroxyalkyl cellulose (HEMC).

Example 3: Evaluation of the perfume delivery performance and perfume quality of the soap bar composition according to the present invention.

A control soap bar composition (Ex C1) and the composition according to the present invention (Ex 3) having formulation as provided in Table 2 were prepared and 0.14 wt.% of citronella perfume was incorporated into each soap bar composition. Test fabrics were washed under similar conditions using each of the soap bar composition (Ex C1 and Ex 3). A group of trained panellists, then evaluated the perfume performance under following conditions (a) perfume delivery of the soap bar composition as is, (b) the perfume delivery in wash and (c) the perfume delivery of the damp fabric, the evaluation details are provided in table 3.

Table 3

As seen from the data provided in table 3, the perfume performance was better in Ex 3 as compared to the comparative composition Ex C1.

Example 4: Determination of the surface properties of the soap bar composition: The dynamic surface tension was measured at a temperature of 25°C on a BP100 Tensiometer (Kriiss GmbH, Germany) using the maximum bubble pressure method between 10 and 50 000 ms surface age. From the kinetic curves showing the time evolution of the surface tension the value at 100 ms was chosen, because typically it correlates well with the characteristic time of air entrapment and bubble formation in hand washing. The dynamic surface tension in mN/m was reported at 100 ms interval.

The dynamic surface tension of soap solution prepared using 24° FH water was recorded and is provided in table 4 below.

Table 4

As shown in table 4, the dynamic surface tension of an aqueous solution of the soap bar composition according to the present invention (Ex 3) is lower than that of the control composition (Ex C1) under similar conditions. A lower dynamic surface tension indicates that the cleaning action of the soap bar composition according to the present invention (Ex 3) is better than the control composition (Ex C1). Further a lower dynamic surface tension also indicates better foam volume.

Claims

39

Claims

1 A soap bar composition comprising: i) 15 wt.% to 60 wt.% fatty acid soap; ii) a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof; iii) a hydroxyalkyl alkyl cellulose; and, iv) 33 wt.% to 45 wt.% water.

2 A bar composition according to claim 1 wherein the silicate structuring agent is formed in-situ.

3 A bar composition according to claim 1 or claim 2 wherein the alkali metal silicate is sodium silicate.

4 A bar composition according to claim 1 wherein the hydroxyalkyl alkyl cellulose is a hydroxyalkyl methylcellulose, preferably selected from the group consisting of hydroxyethyl methyl cellulose, hydroxypropyl methylcellulose and mixtures thereof.

5 A bar composition according to any one of the preceding claims comprising a further silicate structuring agent selected from the group consisting of magnesium silicate, hydrated magnesium silicate, sodium aluminosilicate or combinations thereof.

6 A bar composition according to any one of the preceding claims wherein the silicate structuring agent is a mixture of sodium silicate and a further silicate structuring agent which is hydrated magnesium silicate.

7 A bar composition according to any one of the preceding claims wherein the fatty acid soap comprises a combination of long chain soap molecules having chain 40 length of Cu or greater and short chain soap molecules having a chain length of C12 or below. A bar composition according to any one of the preceding claims wherein the composition comprises from 0.1 wt.% to 5 wt.% hydroxyalkyl alkyl cellulose. A bar composition according to any one of the preceding claims wherein the composition comprises from 1 wt.% to 20 wt.% silicate structuring agent. A bar composition according to any one of the preceding claims wherein the composition comprises a cationic polymer. A bar composition according to any one of the preceding claims wherein the composition includes less than 5 wt.% inorganic or organic adjunct materials, preferably less than 5 wt.% water insoluble particulate adjunct materials. A process for preparing the soap bar composition according to any one of the preceding claims, the process comprising the steps of: i) neutralizing one or more fatty acid or fat with an alkaline material to obtain fatty acid soap; ii) adding a silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof, hydroxyalkyl alkyl cellulose and water to the fatty acid soap formed in step (i) to form a dough mass; iii) converting the resulting dough mass into a shaped soap bar composition, wherein the shaped soap bar composition 15 wt.% to 60 wt.% fatty acid soap and 33 wt.% to 45 wt.% water. Use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved bar properties. 41 Use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing improved fragrance performance. Use of a hydroxyalkyl alkyl cellulose, silicate structuring agent wherein the silicate structuring agent is selected from the group consisting of alkali metal silicate, calcium silicate or mixtures thereof and 33 wt.% to 45 wt.% water in a soap bar composition having 15 wt.% to 60 wt.% fatty acid soap for providing cleaning performance.