CLIAMS:1. A floating soap bar formulation comprising

a. at least one solid material;
b. at least one liquid material; and
c. at least one cosmetically acceptable excipients

wherein the ratio between the liquid materials to solid materials ranges from 2:1 to 10:1.

2. The floating soap bar formulation as claimed in claim 1, wherein the said at least one solid material is selected from group comprising polymer, binders and combinations thereof.

3. The floating soap bar formulation as claimed in claim 2, wherein the said polymer, binder and combination thereof is selected from a group comprising PEG 4000, PEG 6000, PEG 8000, PEG 14000, paraffin wax and combinations thereof.

4. The floating soap bar formulation as claimed in claim 1, wherein the said at least one liquid material is selected from a group comprising polyols, polymers and combinations thereof.

5. The floating soap bar formulation as claimed in claim 4, wherein the said polyols, polymers and combinations thereof are selected from a group comprising Propylene glycol, Glycerin, Sorbitol, PEG 400.

6. The floating soap bar formulation as claimed in claim 1, wherein amount of said solid materials ranges from 2-6% wt.

7. The floating soap bar formulation as claimed in claim 1, wherein amount of said liquid materials ranges from 15-25% wt.

8. The process for preparation of floating soap bar of claim 1 comprising:
a. Melting at least one fatty acid to obtain a molten mass;
b. Adding metal oxides, salts, surfactants, at least one liquid material and at least one solid material to molten mass of step 1 to obtain a molten mixture;
c. Neutralizing the fatty acids in the molten mixture of step 2 by homogenizing with alkali to obtain a homogenized mass; and
d. Adding other cosmetically acceptable excipients additives such as fatty acid, BHT, EDTA, fragrances to the homogenized mass of step 3 and molding it to obtain floating bar the present invention. ,TagSPECI:Field of the invention

The present invention relates to floating soap bars, more particularly the present invention relates to a floating soap bar formulation with improved bar hardness, improved bar finish and reduced stickiness.

Background of the invention

Floating soap bars for bath and toilet use are gaining much commercial importance in view of their advantages over the soaps that do not float over the surface of water and rapidly disintegrate. Floating soap is unique in its sensorial appeal to the consumers. For cosmetic products like soaps, it is highly desirable for the soap to have a smooth surface finish, sufficient hardness and impressive visual appearance as it influences the consumer psychology. Manufacturing of Floating soaps require an air entrapment/ aeration step to achieve a density lower than water. As a result of which floating soaps are often soft and do not have uniform surface finish. It is therefore desirable to produce floating soaps that show improved hardness and have good surface finish.

WO 2007042078 relates to a mixture for producing floating combi-bar floating in water at 20 0C and having a density below 0.99821 g/mL at 20 0C. The invention also discloses a method for producing the said floating combi-bar. The floating combi-bar according to this invention also does not require an aeration step during preparation process to attain buoyancy. Upon hardening at room temperature, the combi-bar is able to float when placed in water. The mixture preferably comprises of 25 - 40 wt.%, of one or more solid non-soap surfactants, 35 - 55 wt.%, of one or more free C14-C18 fatty acids; 5 - 25 wt.%, of one or more metal C8-C24 fatty acid soaps, and 2 - 20 wt.%, of further ingredients, said mixture containing less than 10 wt.% of water as a further ingredient. The process of manufacture also involves the usage of Polyethylene glycol of molecular weight 6000 as part of the translucent soap base to improve the hardness of the floating combi-bar.

EP 1618175 relates to aerated low density cast detergent bars. The invention particularly relates to a process for preparing aerated low density cast detergent bars, wherein the air has been stabilized in the formulation which would aid in producing low density bars, without affecting their user properties.

WO 1998053038 discloses a process for forming detergent bars comprising applying pressure to a detergent composition contained within a mould cavity. The detergent composition in the mould is in a substantially fluid or semi-solid state and the mould is substantially full before the pressure is applied.

Prior art reported many attempts to manufacture Floating soaps by air entrapment/ aeration step to achieve a density lower than water. However none of the prior arts described so far dealt with production of floating soaps with hardness and good surface finish. Present invention therefore aims at producing floating soaps by air entrapment step yet eliminating the associated problems like lack of hardness and good surface finish.

Objects of invention

An object of the present invention is to overcome the drawbacks of the prior art.

Another object of the present invention to provide a floating soap formulation with improved bar hardness, improved bar finish and reduced stickiness.

Yet another object of the present invention is to provide a floating soap formulation by using air entrapment step yet achieving improved hardness and good surface finish.

Yet another object of the present invention is to maintain a unique combination of liquid materials (e.g. solvents/ binders) to solid materials (e.g. polymers/ binders) ratio that is critical to achieve the required viscosity profile during processing step and to achieve sufficient hardness and smooth surface finish after solidification.

Summary of the present invention:

An aspect of the present invention is to provide a floating soap bar formulation comprising

a. At least one solid material;
b. At least one liquid material; and
c. At least one cosmetically acceptable excipients;

wherein the ratio between the liquid materials to solid materials ranges from 2:1 to 10:1.

Brief Description of the Accompanying Drawings:
Figure 1 illustrates improved surface finish and reduction in air gap achieved by the new prototypes of invention as compared to the conventional floating soap formulation.

Detailed description of the present invention:

Conventional process of making floating soaps involves aeration step which requires the viscosity of the molten soap to be maintained adequately to enable air entrapment and to achieve required density for the soap to float on the water surface. These conventional processes are complex and floating soaps made by the air entrapment process are soft and sticky with a non-uniform surface finish. The present invention provides a unique floating soap formulation by air entrapment method yet imparts improved bar hardness, soap aesthetics, without any stickiness.

In accordance with the present invention the floating soap formulation comprises:
a. at least one solid material;
b. at least one liquid material; and
c. at least one cosmetically acceptable excipient

wherein the ratio of the at least one liquid materials to at least one solid material ranges from about 2:1 to about 10:1.

It is noted by the applicants that when the ratio of liquid material to solid materials is maintained specifically in a range of 2:1 to 10:1, desired hardness and surface finish is achieved. Floating soap bar so formed also attains the required density to float over the water surface.

The at least one solid material as may be used in the present invention may be selected from a group comprising but not limited to polymers, binders and combinations thereof. Non limiting examples of solid materials as may be used in the soap formulation of the present invention include solid materials such as PEG 4000, PEG 6000, PEG 8000, PEG 1400, Paraffin wax etc., which melt at higher temperatures (>60 °C) and behave as liquids during the processing steps (a pre-requisite in the process). These materials maintain the viscosity required for air entrapment during the processing conditions. The amount of solid materials in the composition of the present invention ranges from 1 to 10 % wt., particularly from 2 % to 6%.

The at least one liquid material as may be used in the present invention may be selected from a group comprising but not limited to solvents, binders and combination thereof. Non limiting examples of liquid materials as may be used in the soap formulation of the present invention comprise Propylene glycol, Glycerin, Sorbitol, PEG 400.The amount of liquid materials in the composition of the present invention ranges from 5 % to 30 % wt, particularly from 15 % to 25 %.

The at least one cosmetically acceptable excipient may be selected from a group comprising but not limited to in-situ soap base, surfactants, water, free fatty acids, preservatives, fragrance and combinations thereof.

The in-situ soaps used in the composition can be chosen from group comprising, but are not limited to sodium or potassium salts of stearate, laurate, myristate, palmitate, saponified glycerides such as sodium palmate, sodium palm kernelate and sodium cocoate and combinations thereof. The amount of the soaps ranges from 15 % to 50 % wt., particularly from 35 % to 45%.

The surfactants used in the composition can be surfactant chosen from group comprising, but are not limited to synthetic, anionic, zwitterionic, amphoteric, semi-polar nonionic, nonionic surfactant and mixtures thereof. The amount of the surfactant ranges from 5% to 30 % wt., particularly from 10 to 20%.

The surfactants used in the present invention may be selected from a group comprising, but are not limited to anionic surfactants, amphoteric surfactants, nonionic surfactants, and any combinations thereof. As it is well known in the art that surfactant materials can also be an emulsifier, the term “surfactant” does not exclude materials which also have emulsification properties.

The anionic surfactants that may be used in the present invention include but are not limited to alkyl sulfates, anionic acyl sarcosinates, anionic alkyl sarcosinates, methyl acyl taurates, N-acyl glutamates, acyl isethionates, alkyl ether sulfates, alkyl sulfosuccinates, alkyl phosphate esters, ethoxylated alkyl phosphate esters, trideceth sulfates, protein condensates, mixtures of ethoxylated alkyl sulfates and the likes. Alkyl chains for these surfactants are C8-C22, preferably C10-C18 and, more preferably, C12-C14 alkyls.

The amphoteric surfactants which can be used in the compositions of the present invention are those which can be broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within this definition are sodium 3-dodecylaminopropionate, sodium 3-dodecylaminopropane sulfonate. Other amphoterics such as betaines are also useful in the present composition. Examples of betaines useful herein include the high alkyl betaines such as coco betaine, coco dimethyl carboxymethyl betaine, lauryl dimethyl carboxy-methyl betaine, lauryl dimethyl alpha-carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2-hydroxyethyl)carboxy methyl betaine, stearyl bis-(2-hydroxypropyl)carboxymethyl betaine, oleyl dimethyl gamma-carboxypropyl betaine, lauryl bis-(2-hydro-xypropyl)alpha-carboxyet-hyl betaine, etc. The sulfobetaines may be represented by coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, amido betaines, amidosulfobetaines, and the like.

The nonionic surfactants useful in this invention can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. Non-limiting examples of preferred nonionic surfactants for use herein are those selected form the group consisting of glucose amides, alkyl polyglucosides, sucrose cocoate, sucrose laurate, alkanolamides, ethoxylated alcohols and mixtures thereof. In a preferred embodiment the nonionic surfactant is selected from the group consisting of glyceryl monohydroxystearate, isosteareth-2, trideceth-3, hydroxystearic acid, propylene glycol stearate, PEG-2 stearate, sorbitan monostearate, glyceryl laurate, laureth-2, cocamide monoethanolamine, lauramide monoethanolamine, decyl glucoside and mixtures thereof. The composition of the present invention may also comprise one or more sugar based surfactants selected from but not limited to condensation products of long chain alcohols with sugar or starch polymers (e.g. decyl polyglucoside and lauryl polyglucoside), amides (e.g. cocoamide diethanolamine and cocoamide monoethanolamine), alkylene oxide derived surfactants (e.g. ceteth-6, ceteareth6, steareth-6, PEG-12 stearate, and PEG-200 glyceryl tallowate), Maltooligosyl Glucoside/Hydrogenated starch Hydrolysate and mixtures thereof. Preferred sugar based surfactants include Maltooligosyl Glucoside/Hydrogenated starch Hydrolysate and Alkyl polyglucoside.

The amount of water used in the composition of the present invention ranges from 2 to 20 % wt., preferably from 2% to 15%.

The free fatty acids in the composition of the present invention can be chosen from a group comprising, but are not limited to material ranging in hydrocarbon chain length of about 8 to about 18 or above. The amount of free fatty acids required ranges from 1 % to 10 % wt., preferably from 1 % to 5 %.

The “free fatty acids” as used herein are selected from, but are not limited to fatty acids with alkyl chain lengths of from C8 – C18. These may be selected from group of linear chained fatty acids, branched chain fatty acids, saturated and unsaturated fatty acids such as Caprylic, Capric, Lauric, Myristic, Palmitic, Stearic, Oleic, etc and mixtures thereof.

The metal oxide added in the composition of the present invention can be chosen from a group comprising, but are not limited to TiO2, ZnO, MgO, SiO2 and combinations thereof. The metal oxide may be present in an amount of from about 0.01% to about 2% preferably from about 0.1 to about 1%.

The alkali added in the composition of the present invention can be chosen from a group comprising but not limited to sodium hydroxide, potassium hydroxide. The amount of the alkali ranges from 4 to 20% by wt, preferably from 6 to 15% by wt.

The preservatives added in the composition of the present invention can be chosen from a group comprising, but are not limited to dimethyloldimethylhydantoin, parabens, BHT, EDTA, sorbic acid, phenoxy ethanol and combination thereof. The amount of preservative ranges from 0.01 to 0.5 % wt., preferably from 0.02 % to 0.2%.

The fragrances added in the composition of the present invention can be chosen from a group comprising, but are not limited to essential oils, natural fragrance, synthetic fragrances or combination thereof. The amount of fragrance required ranges from 0.1 to 1.5% wt., preferably from 0.5 % to 1.3 %.

In the present invention the ratio of liquid materials (solvents/ binders) to solid materials (polymers/ binders)is maintained specifically in a range of 2:1 to 10:1 in order to achieve the required hardness and surface finish and also to impart the required density for the soap to float over the water surface.

Another embodiment of the present invention provides a process for the preparation of floating soap with improved bar hardness and surface finish comprising the steps:

a. Melting at least one fatty acid to obtain a molten mass;
b. Adding metal oxides, salts, surfactants, at least one liquid material and at least one solid material to molten mass of step 1 to obtain a molten mixture;
c. Neutralizing the fatty acids in the molten mixture of step 2 by homogenizing with alkali to obtain a homogenized mass; and
d. Adding other cosmetically acceptable excipients additives such as fatty acid, BHT, EDTA, fragrances to the homogenized mass of step 3 and molding it to obtain floating bar the present invention.
Another specific embodiment of the present invention provides a process for the preparation of floating soap with improved bar hardness and surface finish comprising the steps:

a. Melting at least one fatty acid in mixer at 40-650C (40-50 rpm) to obtain a molten mass;
b. Adding metal oxides, salts, surfactants, at least one liquid material and at least one solid material to molten mass of step a and mixing for 10-15 min (45-55 rpm) at a temperature of 65-800C to obtain a molten mixture;
c. Neutralizing the fatty acids in the molten mixture of step 2 by homogenizing with alkali to obtain a homogenized mass at a temperature of about 80-920C for 70-80 minutes (55-75 rpm) to obtain a homogenized mass; and
d. Mixing other cosmetically acceptable excipients additives such as fatty acid, BHT, EDTA, fragrances to the homogenized mass of step 3 for about 5-10 min (50-70 rpm) and molding it to obtain floating bar the present invention.

The present invention is now illustrated by way of non-limiting examples.

Example-1: Formulation where no PEG is used but ratio of liquid material (solvents/ binders) to solid materials (polymers/ binders) is maintained (working example)

Table 1
Ingredients Weight (%)
Lauric acid 14.5
Hystric Acid 26
Sorbitol (70%) (Liquid material) 12
PEG 400 (Liquid material) 0
Propylene Glycol (Liquid material) 8.7
Glycerin (Liquid material) 3
PEG 6000 (Solid material) 0
Paraffin Wax (solid material) 2.5
ZnO 0.2
TiO2 0.5
Tinopal X 0.1
AOS (90 % powder) 11.05
CMEA 1.8
SLES 1EO 70% 2
CAPB (29% SOLN) 1
DI Water 1
NaOH (47.5% SOLN) 12.7
EDTA-Tetra Sodium (98%) 0.05
BHT 0.05
Sodium bicarbonate 1
NaCl 0.5
Phenoxy Ethanol 0.05
Perfume 1.3

Ratio of Liquid materials (e.g. solvents/ binders) to Solid materials (e.g. polymers/ binders) is 9.48: 1

Observation: Floating soap bar of desirable consistency, hardness and surface finish is obtained.

Example 2: Working example

Table 2:
Ingredients Weight %
Lauric acid 14.50
Hystric Acid 26.00
Sorbitol (70%) ( Liquid material) 8.00
PEG 400 ( Liquid material) 2.00
Propylene Glycol ( Liquid material) 7.70
Glycerin ( Liquid material) 3.00
PEG 6000 ( Solid material) 3.50
Paraffin Wax ( Solid material) 2.00
ZnO 0.20
TiO2 0.50
Tinopal X 0.10
AOS (90 % powder) 11.05
CMEA 1.80
SLES 1EO 70% 2.00
CAPB (29% SOLN) 1.00
DI Water 1.00
NaOH (47.5% SOLN) 12.70
EDTA-Tetra Sodium (98%) 0.05
BHT 0.05
Sodium bicarbonate 1.00
NaCl 0.50
Phenoxy Ethanol 0.05
Perfume 1.30

Ratio of Liquid material to Solid material is 3.76:1

Observation: Floating soap bar of desirable consistency, hardness and surface finish is obtained.

Example 3: Formulation where High molecular weight PEGs is used but ratio of liquid material (solvents/ binders) to solid materials (polymers/ binders) is not maintained. Non working example

Table 3
Ingredients Weight (%)
Lauric acid 14.50
Hystric Acid 26.00
Sorbitol (70%) (Liquid material) 11.40
PEG 400 (Liquid material) 3.30
Propylene Glycol (Liquid material) 7.50
Glycerin (Liquid material) 2.00
PEG 6000 (solid material) 1.8
Paraffin Wax (solid material) 0.20
ZnO 0.20
TiO2 0.50
Tinopal X 0.10
AOS (90 % powder) 11.05
CMEA 1.80
SLES 1EO 70% 2.00
CAPB (29% SOLN) 1.00
DI Water 1.00
NaOH (47.5% SOLN) 12.70
EDTA-Tetra Sodium (98%) 0.05
BHT 0.05
Sodium bicarbonate 1.00
NaCl 0.50
Phenoxy Ethanol 0.05
Perfume 1.30

Ratio of Liquid materials (e.g. solvents/ binders) to Solid materials (e.g. polymers/ binders): 12.1:1

Observation: Aerated soap bar formed is soft and does not have smooth surface finish moreover displays air gaps.

Example 4: non working example:

Table 4:
Ingredients Weight (%)
Lauric acid 14.5
Hystric Acid 26
Sorbitol (70%) (Liquid material) 7.6
PEG 400 (Liquid material) 1
Propylene Glycol (Liquid material) 6
Glycerin (Liquid material) 2
PEG 6000 (Solid material) 5
Paraffin Wax (Solid material) 4.6
ZnO 0.2
TiO2 0.5
Tinopal X 0.1
AOS (90 % powder) 11.05
CMEA 1.8
SLES 1EO 70% 2
CAPB (29% SOLN) 1
DI Water 1
NaOH (47.5% SOLN) 12.7
EDTA-Tetra Sodium (98%) 0.05
BHT 0.05
Sodium bicarbonate 1
NaCl 0.5
Phenoxy Ethanol 0.05
Perfume 1.3

Ratio of Liquid material to Solid material is 1.73:1

Observation: Bar does not float.

Example 5: Comparative analysis of Bar hardness, Lather volume and Stickiness for floating soap formulations prepared by present invention Versus conventional floating soap formulations.

Table 5
Property Formulation as per present invention Conventional floating soap formulation
Bar hardness, PV (mm) 2-8 10-18
Lather volume (mL) @30 FH 460-480 460-480
Stickiness (score)* 3 4

* The stickiness of the bars (both old and new formulation) was evaluated by ten panelists. Based on the extent of stickiness, the panelists rated the two soaps on a scale of 1-5 and the scores for stickiness are defined as follows:

1 2 3 4 5
Dry Optimal Neither Sticky nor dry Sticky Very Sticky

Observation: Floating soaps prepared according to present invention were demonstrated to possess improved bar hardness and reduced stickiness compared to conventional floating soap formulation. This is further confirmed by measuring the Pv values by needle penetration method. Higher the Pv values lesser is the bar hardness.
The needle penetration method is used to measure the hardness of a given soap. Test is carried out as follows:
Step1: The needle is placed perpendicular to the soap such that it touches the surface of the soap
Step 2: Next a load measuring 50 g is applied on the needle and held for 30 sec. with constant pressure.

Step 3: The needle penetration depth (in mm) in soap after 30 sec. is recorded to obtain Pv value.

[Note: More Pv value (in mm) represents softer bar].