CLIAMS:1. A coating soap formulation comprising

a) A hydrophobic material;
b) A hydrophilic material; and
c) Cosmetically acceptable excipients.

Wherein, the ratio of hydrophobic to hydrophilic material is from 10:1 to 20:1; and

Wherein the amount of film forming polymer and structurant of the cosmetically acceptable excipients together in the formulation is greater than 3% wt.

2. The coating soap formulation as claimed in claim 1, wherein said hydrophobic material are selected from a group comprising film forming polymer of higher molecular weight, high molecular weight PEG, solid paraffin wax and structurant.

3. The coating soap formulation as claimed in claim 1, wherein said hydrophillic material is selected from a group comprising solvents and aqua.

4. The coating soap formulation as claimed in claim 3, wherein said solvents are selected from a group comprising polyols i.e. glycerin, sorbitol, propylene glycol

5. The coating soap formulation as claimed in claim 1, wherein said film forming polymer is selected form a group comprising synthetic polymer or copolymer that is polymerized from an ethylenically unsaturated monomer like ethylenically unsaturated monomers include vinyl alcohol, vinyl acetate, vinyl propionate, N-vinyl acetamide, N-vinyl pyrrolidone, N-vinyl caprolactam, acrylic acid, methacrylic acid, C1-C12 esters of acrylic and methacrylic acid, acrylamide, methacrylamide, crotonic acid, vinyl neodecanoate, styrene, vinyl laurate, N-tertiary butyl acrylamide, methyl vinyl ether, ethylene, monobutyl maleate, maleic anhydride, allyl acetate, isobutyl vinyl ether, N,N-dimethylaminoethyl (meth) acrylate and its derivatives quaternized with dimethyl and diethyl sulfate, diallyl dimethyl ammonium chloride, vinyl substituted siloxanes or mixtures thereof.

6. The coating soap formulation as claimed in claim 1, wherein amount of said film forming polymer ranges from 0.01 to 3% wt., preferably from 1 to 2% wt.

7. The coating soap formulation as claimed in claim 1, wherein said structurant in accordance with the present invention is selected from group comprising biopolymers such as starch, modified starch, guar gum, tamarind kernel polysaccharide or psyllium husk; inorganics particles such as talc, calcite, clays, alumino silicate, calcium silicate, calcium alumino silicate, boro silicate, boro alumino silicate, alumina, sodium phosphate, alumino phospho silicate or silica and combinations thereof.

8. The coating soap formulation as claimed in claim 1, wherein amount of said structurants ranges from 0.5 to 5% wt., particularly from 1 to 3% wt. ,TagSPECI:Field of the invention:

The present invention relates to coating of an opaque soap / bathing bar, more particularly the present invention relates to coating of opaque soap bar to enhance the retention of moisture fragrance, color and prevention of efflorescence (brownish spots) of opaque soap/bathing bar.

Background of the invention:

A wide range of soap compositions are available today for personal care and hygiene. Prior art teaches a variety of cleansing formulations that are manufactured as transparent or opaque soaps and provide many beneficial effects to the consumers. Although opaque soaps are widely used, their acceptance by consumers is limited in view of some associated drawbacks such as efflorescence due to the presence of salt or electrolytes that emerge out from the formulation or water during its use and appear in the form of white spots over the soap surface. Added to this, opaque soaps upon contact with heavy metal ions lead to discoloration and patch formation over the surface of soap which is not at all desirable. These extreme influences from the above factors leads to poor bar aesthetics.

In order to overcome these problems opaque soaps are provided with an external coat using various materials like polymers or hydrophobic materials. However these materials when used leads to formation of hydrophobic film which further leads to reduction in in-use sensory (specifically lather). Moreover these material will allow the water and fragrance to escape from the soap body during hot and dry conditions which would lead to a very hard soap with poor in-use sensory.

955/MUM/2002 discloses a method of providing water-resistant coated bars/shaped solid such as detergent/cleaning composition in bar form usually used for cleaning hard surfaces/fabric/personal cleansing. Further it provides a system for carrying out such method to produce said bar with desired selective surface coating. The process of coating as disclosed in the prior art provides water barrier coat on bar / shaped solid forms of detergent/cleansing formulations adapted to serve as a sacrificial water resistant coating such that only during application of the bar the external coat gets abraded or wears-off. While during its storage and non-application so long as the coated surface is not subject to any abrasive action the water barrier coat remains to favor avoiding physical disintegration/sogging of the bar in contact with water.
EP 0545716 A1 discloses a dual-phase toilet bar, having a first portion that is translucent and a second portion that is opaque. Each portion of the bar has at least 80% by weight of its components identical. The opaque portion incorporates a solid particulate opacifying agent. The process of preparing the said toilet bar involves pouring of a clear composition into a mould to partly fill same and thereafter, an opaque composition is poured into the remaining volume of the mould, this composition being essentially identical to the clear composition but also including a small amount of solid particulate opacifying agent. Alternatively, the opaque composition can be poured first into the mould followed by the clear composite. The important component of the soap bar of EP0545716 is a solid particulate opacifying agent, present in an amount from about 0.1 to about 5% by weight and the opacifying agent used may be titanium dioxide, in coated or uncoated form, alumina, zinc oxide, calcium carbonate and other inorganic minerals providing a white background as well as combinations thereof.
EP 0979267A4 relates to a transparent soap bar and a process for inhibiting the formation of surface haze on transparent soap bars. The process steps comprises (a) providing a finished transparent soap bar; (b) providing a coating component selected from the group consisting of water, a C1-C8 aliphatic alcohol, a polyol, and mixtures thereof; (c) applying the coating component onto the finished transparent soap bar to form a coated transparent soap bar; and (d) immediately packaging the coated transparent soap bar.

US7045491 discloses that the combination of an efficient bar soap with effective cleansing and bar aesthetics has been often attempted and accordingly provides a cleansing bar compositions which are translucent, pearlized, or opaque; have good structural integrity; exhibit good cleansing properties; and provide effective and mild cleansing, pleasing aesthetics, and a low wear rate. Further US ‘491 teaches that a combination of (dibenzylidene sorbitol) DBS and glycerin gives an especially good product, especially as it relates to forming a soap bar which is not clear, and exhibits a longer life as compared to a DBS only bar. The richness of the aesthetics of the non-clear bar can also be enhanced by the inclusion of encapsulated fats/oils or emollient esters the form of beads.

Hence there is a need to provide an opaque soap or bathing bar coated with another bathing bar composition through enrobing or pan coating with granulator. The opaque mass has higher ratio of hydrophobic to hydrophilic material to prevent water and fragrance loss from the main soap mass. This can be achieved by coating the soap/bathing bar with a material that is preferably a bathing bar which is cost effective, easy to process and can impart soap like or bathing bar properties during use. This in turn helps in maintaining the uniform product performance throughout the shelf life of product. The process will also help to enhance the shelf life of soap (i.e. from current 18 months to more than 36 months).

Object of the present 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 coating bathing bar composition which is coated over an opaque soap or bathing bar through enrobing or pan coating with granulator in a cost effective manner.

Yet another object of the present invention is to provide a coating bathing bar formulation that has effective binding ability with main body of opaque soap/bathing bar which has to be coated.

Yet another object of the invention is to provide a coating bathing bar formulation which is stable (in terns of color and fragrance stability) at high temperature (70-950C) for a long period of time (i.e. > 12 hours) and has similar or better lather profile and improved bar aesthetics.

Summary of the present invention:

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

a. A hydrophobic material;
b. A hydrophilic material; and
c. Cosmetically acceptable excipients.

Wherein, the ratio of hydrophobic to hydrophilic material is from 10:1 to 20:1; and

Wherein the amount of film forming polymer and structurant of the cosmetically acceptable excipients together in the formulation is greater than 3% wt.

Brief description of the drawings:

Figure 1 illustrates the compatibility between the two layers (coated layers and the main soap body).

Figure 2 illustrates the comparison of coated soap bar (present invention) with that of non-coated soap in terms of color stability and efflorescence.

Detailed description of the invention:

The present invention provides an opaque soap or bathing bar coated with another bathing bar through enrobing or pan coating with granulator in a cost effective manner. The coated opaque soap is said to be stable at high temperature (70-950C) for a long period of time (i.e. > 12 hours) and has similar or better lather profile (in use condition), with similar soap quality maintained throughout, along with improved bar aesthetics.

An embodiment of the present invention provides an opaque soap bar coated with another bathing bar. The composition of the present invention comprises of:

a. an opaque soap bar
b. a coated bathing bar

The opaque soap bar is the conventional soap bar on which the coating soap formulation of the present invention is coated to achieve the desired results. Examples of the opaque soap bar are disclosed in the examples but these are not to limit the scope of the soap bar to be coated. A person skilled in the art would know the conventional composition and methods of preparation of an opaque soap bar.

The coating bathing bar comprises of surfactant, free fatty acid (C16-C18), film forming polymer (high mw), high molecular weight PEG (4000-8000), metal oxides, salt, solvent, solid paraffin wax, structurant, soap, preservatives, pH regulator, color, fragrance, emotive and aqua.

The surfactant present in the composition of the coated opaque bathing bar can be chosen from a group comprising synthetic, anionic, amphoteric and nonionic surfactant. The amount of surfactant required for the composition of the present invention ranges from 10 to 60% wt., preferably from 20 to 50% wt.

The synthetic surfactants used in the present invention may be selected from a group comprising 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 like. Alkyl chains for these surfactants are C8-22, preferably C10-18 and, more preferably, C12-14 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 “free fatty acids” as used herein are selected from 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 amount of free fatty acids required ranges from 0.5 to 20% wt., preferably from 5 to 10% wt.

The film forming polymer can be a synthetic polymer or copolymer that is polymerized from an ethylenically unsaturated monomer or mixtures thereof. Preferred ethylenically unsaturated monomers include vinyl alcohol, vinyl acetate, vinyl propionate, N-vinyl acetamide, N-vinyl pyrrolidone, N-vinyl caprolactam, acrylic acid, methacrylic acid, C1-C12 esters of acrylic and methacrylic acid, acrylamide, methacrylamide, crotonic acid, vinyl neodecanoate, styrene, vinyl laurate, N-tertiary butyl acrylamide, methyl vinyl ether, ethylene, monobutyl maleate, maleic anhydride, allyl acetate, isobutyl vinyl ether, N,N-dimethylaminoethyl (meth) acrylate and its derivatives quaternized with dimethyl and diethyl sulfate, diallyl dimethyl ammonium chloride, vinyl substituted siloxanes or mixtures thereof. The amount of the same required ranges from 0.01 to 3% wt., preferably from 1 to 2% wt.

The amount of PEG present in the composition of the present invention ranges from 1 to 5% wt., particularly from 2 to 3% wt.

Metal oxides that may be used in the present invention may be selected from the group comprising but not limited to titanium dioxide, silicone dioxide, magnesium oxide, zinc oxide, iron oxide, silver oxide. The amount of the metal oxides ranges from 0.05 to 0.8% wt., more particularly from 0.05 to 0.4% wt.

Salts in accordance with the present invention is selected from group comprising sodium chloride, sodium sulfate, sodium lactate, sodium glycolate, sodium citrate, potassium chloride, potassium sulfate, magnesium chloride, calcium chloride and combinations thereof The amount of salts ranges from 0.1 to 1% wt., particularly from 0.4 to 0.8% wt.

Solvent that may be used in the present invention include Propylene glycol (PG), glycerine, and sorbitol. The amount of the solvents ranges from 0.1 to 2% wt., particularly from 0.4 to 1.5% wt.

The amount of solid paraffin wax required ranges from 1 to 12% wt., more particularly 2 to 10% wt.

The structurant in accordance with the present invention is selected from group comprising biopolymers such as starch, modified starch, guar gum, tamarind kernel polysaccharide or psyllium husk; inorganics particles such as talc, calcite, clays, alumino silicate, calcium silicate, calcium alumino silicate, boro silicate, boro alumino silicate, alumina, sodium phosphate, alumino phospho silicate or silica and combinations thereof The amount of the structurants ranges from 0.5 to 5% wt., particularly from 1 to 3% wt.

Preferably, the soap composition of the present invention may comprise alkali metal salts of fatty acids such as sodium palmitate and sodium oleate (i.e. anionic surfactants). Among the soaps that are used herein may be saponified glycerides such as sodium palmate, sodium palm kernelate and sodium cocoate. The amount of the soap ranges from 5 to 30% wt., particularly from 10 to 20% wt.

Preservatives according to the present invention include BHT, EDTA, phenoxy ethanol. The amount of the preservatives ranges from 0.01 to 0.1% wt., more particularly from 0.03 to 0.05% wt.

pH regulator according to the present invention includes citric acid, lactic acid, oxalic acid, acetic acid etc. pH regulator can be present in amounts 0.2 to 2 % by weight in the final product, preferably from 0.3 to 0.7% wt.

The colors can be selected from a group comprising C.I. Pigment Black 7 (C.I. 77266), C.I. Pigment Blue 15 (C.I. 74160), C.I. Pigment Blue 15:1 (C.I. 74160), C.I. Pigment Red 4 (C.I. 12085), C.I. Pigment Red 5 (C.I. 12490), C.I. Pigment Red 112 (C.I. 12370), C.I. Pigment Red 181 (C.I. 73360), C.I. Vat Red 1 , C.I. Pigment Green 7 (C.I. 74260), C.I. Pigment Violet 23 (C.I. 51319), C.I. Pigment Yellow 1 (C.I. 11680), C.I. Pigment Yellow 3 and the likeThe amount of color added ranges from 0.1 to 2% wt., particularly from 0.5 to 1% wt.

The fragrance may be selected from a group comprising musk oil, civet, castreum, ambergris, plant perfumes such as sandalwood oil, bergamot oil, lemon oil, lavender oil, sage oil, rosemary oil, peppermint oil, eucalyptus oil, menthol, camphor, verbena oil, citronea oil, cauout oil, salvia oil, clove oil, chamomie oil, sandalwood oil, costus oil, labdanum oil, broom extract, carrot seed extract, jasmine extract, minmosa extract, narcissus extract, obanum extract, rose extract and the like, and chemical substances such as acetophenonene, dimethynadane derivatives, naphthaline derivatives, ayl caprate, a-amylcinnamic aldehyde, anethole, anisaldehyde, benzyl acetate, benzyl alcohol, benzyl propionate, borneol, cinnamyl acetate, cinnamyl alcohol, citral citronneal, cumin aldehyde, cyclamen aldehyde, decanol, ethyl butyrate, ethyl caprate, ethyl cinnamate, ethyl vanillin, eugenol, geraniol, hexenol, a-hexylcinnamic aldehyde, hydroxycitrolneal, indole, iso-amyl acetate, iso-amyl iso-valeratek iso-eugenol, nalol, linalyl acetate, p-methylacetophenone, methyl anthranilate, methyl dihydroasmonate, methyl eugenol, methyl-ß-naphthol ketone, methylphenhlcarbinyl acetate, musk ketol, musk xylol, 2,5,6-nanodinol, ?-nanolactone, phenylacetoaldehydodimethyl acetate, ß-phenylethyl alcohol, 3,3,5-trimethylcyclohexanol, ?- undecalactone, undecenal, vanillin and mixtures thereof.and the amount added ranges from 0.1 to 2% wt., particularly from 0.5 to 1% wt.

The emotive may be selected from a group comprising, Houttuynia cordata extract, Phellodendron bark extract, melilot extract, dead nettle extract, licorice extract, peony root extract, soapwort extract, luffa extract, cinchona extract, strawberry geranium extract, sophora root extract, nuphar extract, fennel extract, primrose extract, rose extract, rehmannia root extract, lemon extract, lithospermum root extract, aloe extract, calamus root extract, eucalyptus extract, field horsetail extract, sage extract, thyme extract, tea extract, seaweed extract, cucumber extract, clove extract, bramble extract, lemon balm extract, carrot extract, horse chestnut extract, peach extract, peach leaf extract, mulberry extract, knapweed extract, hamamelis extract, placenta extract, thymic extract, silk extract, and licorice extract, blue lotus extract, sea mineral extract, blueberry extract, black currant extract and the likeThe amount of emotive added ranges from 0.1 to 2% wt., particularly from 0.2 to 0.5% wt.

It is well known that the melting of any opaque soap/present opaque bathing bars requires high temperature (> 200 oC) and high amount of water /solvent percentage (more than 25%). In the present invention coating formulation is designed to process below 100 oC and using less than 10% water content.

Another aspect of the present invention is to provide a coating soap formulation comprising

a. A hydrophobic material;
b. A hydrophilic material; and
c. Cosmetically acceptable excipients.

Wherein, the ratio of hydrophobic to hydrophilic material is from 10:1 to 20:1; and

Wherein the amount of film forming polymer and structurant of the cosmetically acceptable excipients together in the formulation is greater than 3% wt.

If the amount of film forming polymer and structurant is less than 3% wt and the ratio of hydrophobic to hydrophilic to material is less than 1:1 then it would be very difficult to coat and prepare a good barrier for the soap as illustrated in table 4 of example 6.

Hydrophobic material used in the present invention are Film forming polymer (High Mw), High molecular weight PEG (4000-8000), Solid paraffin wax and structurant (Modified starch, methyl cellulose).

Hydrophilic materials are solvents (polyols i.e. glycerin, sorbitol, propylene glycol) and aqua.

Another embodiment of the present invention provides a process for the preparation of the coating soap formulation comprising steps of:

Step 1: Mixing free fatty acid (C16-C18), film forming polymer (high mw), high molecular weight PEG (4000-8000), metal oxides, solid paraffin wax and structurant in a mixer at 65-750C;

Step 2: mixing mixture of step 1 for sufficient time (20-30mins) post melting, aqua and soap is added at a temperature of 85-900C;

Step 3: adding pH regulator followed by surfactants at a temperature between 90-950C;

Step 4: adding other additives like salt, preservatives, color, fragrance, emotive etc once soap and surfactants are mixed completely; and

Step 5: maintain the final mass at 70-90°C temperature in order to achieve pouring consistency of the mixture.

Any coating process can be used to coat the soap in the present invention provided the temperature of the coating mass is maintained at moderate temperature (i.e. between 40 0C to 50 °C).

Yet another embodiment of the present invention provides a process for coating the conventional opaque soap bar with the coating soap formulation of the present invention.

The coating process in the present invention is achieved through enrobing, pan coating with granulator and the likes.

Enrobing process: Enrobing is essentially a mechanized form of hand-dipping. Enrobing with relevant substrate extends the products shelf life. In general enrobing is used in the confectionary industry. In case of soap industry the machine will help to coat the conventional soap with a hot melt soap formulation which is subjected to the enrobing machine.

Pan coating process: Pan Coating is among the oldest industrial processes for forming small coated particles or coated tablets. In case of soap industry the soap bars will be placed inside the pan coater and melt mass of soap will be sprayed through a nozzle on the soap bars/tablets. The pan coater runs for 5-10 minutes so that the melted mass gets solidified.

The process of coating soap bar using coating composition of the present invention comprises steps of:

Step 1: Heating the coating composition of soap to a temperature of 70-900 C to obtain a molten mass;

Step 2: Transferring the melted coating composition of soap as obtained in step (a) to sprayer / nozzle of enrober or pan coater machine;

Step 3: Finished soap bar is fed into the enrober or pan coater machine for coating;

Step 4: The coating composition of soap is sprayed at a temperature of 70-900 C on the surface of the finished soap bar until a uniform layer of coating is achieved on the surface of finished soap bar;

Step 5: The coated finished soap mass obtained in step (d) is allowed to cool at rate of 5-20 °C per minute to the ambient temperature; and

Step 6: The process of spraying and cooling takes place in the enrober or pan coater and the entire process takes around 15 to 20 minutes.

The bathing bar coating formulation is very stable at high temperature (70-95) 0C for a long period of time (i.e. > 12 hours) as illustrated in figure 2. Further, the bathing bar coating formulation has similar or better lather profile in (in –use condition), and similar soap quality is maintained throughout. The coated soap has improved bar aesthetics, which is achieve via coating a very thin layer or coating formulation. The process employs the use of formulating a coating mass which can melt below 100 0C so as to achieve bulk surface coating at less than 100 0C using enrobe machine, pan coating machine or the like. Bathing bar coating formulation has effective binding ability with opaque soap and is difficult to distinguish between the two as illustrated in figure 1.

The coating opaque bathing bar of the present invention uses hydrophobic materials but still maintains in-use and post use sensory. The hydrophobic material is present along with other surface active materials to balance the hydrophobic to hydrophilic ratio to prevent thickening/ water loss/ fragrance loss from the mass. The hydrophobic: hydrophilic ratio balance can also provide a right kind of in-use properties while using this bar. The lather and other in-use properties is very much similar to the normal bathing bar.

The present invention is now illustrated by way of non-limiting examples. The following examples describe and demonstrate the embodiments of the present invention. .

Example 1: Coating composition

Table 1:

Ingredients (coating composition) % Specific weight %
Surfactant 10-60 48.45
Free Fatty Acid (C16-C18) 0.5-20 7
Film forming polymer (High Mw) 0.01-3 2
High molecular weight PEG (4000-8000) 1-5 2
Metal oxides (TiO2, ZnO) 0.05-0.8 0.5
Salt 0.1-1 0.5
Solvent 0.1-2 0.5
Solid paraffin wax 1-12 8
Structurant (Modified starch, methyl cellulose) 0.5-5 4
Soap 5-30 25
Preservatives 0.01-0.1 0.05
pH regulator 0.2-2 0.3
Color / Fragrance / Emotive 0.1-2 1.2
Aqua 0.1 -2 0.5

Example 2: coating of a conventional soap (sample A) with the coating soap formulation (sample B) of the present invention

Table 2:

Ingredients (sample A) conventional opaque soap Range % w/w Exact % w/w
Soap 60-90 74
Aqua 8-14 Q s to 100
Talc 1-7 6
Soda 0.1-0.9 0.5
Lauric acid 0.2-1.0 0.5
Glycerine 0.5-5 4.0
Titanium dioxide 0.1-0.5 0.4
EDTA 0.01-0.10 0.05
BHT 0.01-0.10 0.05
Color/fragrance/emotive 0.8-2 1.40
Ingredients (sample B) coating composition Range % w/w Exact % w/w
Surfactant 10-60 46.45
Free Fatty Acid (C16-C18) 0.5-20 7
Film forming polymer (High Mw) 0.5-3 2
High molecular weight PEG (4000-8000) 1-5 2
Metal oxides (TiO2, ZnO) 0.05-0.8 0.5
Salt 0.1-1 0.5
Solvents 0.1-2 0.5
Solid paraffin wax 1-12 10
Structurant (Modified starch, methyl cellulose) 0.5-5 4
Soap 5-30 25
Preservatives 0.01-0.1 0.05
pH regulator 0.2-2 0.3
Color / Fragrance / Emotive 0.1-2 1.2
Aqua Qs to 100 0.5

Example 3: process of preparation of the opaque soap bar and the coating material (conventional method).

Process of preparing sample A (conventional opaque soap)

Step 1: All the raw material are weighed and mixed in a sigma mixer for 10-20 minutes.

Step 2: Fragrance and emotive are added to the mixture of step 1 and the sigma mixer is operated for 1 minute.

Step 3: The entire mixture obtained in step 2 is milled using TRM (triple roll mill); and

Step 4: The mass is then plodded and stamped in order to obtain the finished soap.

Process for preparing sample B (coating mass)

Step 1: Free fatty acid (C16-C18), film forming polymer (high mw), high molecular weight PEG (4000-8000), metal oxides, solid paraffin wax and structurant are mixed in a mixer at 65-750C;

Step 2: Mixture of step 1 is mixing for sufficient time (20-30mins) post melting, aqua and soap is added at a temperature of 85-900C;

Step 3: pH regulator is added followed by surfactants at a temperature between 90-950C;
Step 4: Other additives like salt, preservatives, color, fragrance, emotive etc are added once soap and surfactants are mixed completely; and

Step 5: The final mass is maintained at 70-900C temperature in order to achieve pouring consistency in mixer.

Example 4: Process for coating sample A (opaque soap) using hot melt sample B (coating mass)

Step 1: Opaque soap/bathing bar in the final finished form is prepared and referred to as Sample A;

Step 2: The coating soap mass is prepared in the molten state at (70-900 C) and referred to as sample B;

Step 3: The sample B is transferred to the enrobing machine, pan coating machine or the like.
Step 4: The sample A mass is dipped into the molten sample B mass having temperature 70-900 C;

Step 5: Both the mass is allowed to cool at ambient temperature;

Step 6: The composite mass (sample A and B together) is brought down to ambient temperature condition. The rate of cooling is 5-20 °C per minute; and

Step 7: The composite soap mass/bathing bar is placed in a carton or soap box.

Example 5: comparative data

Table 3
Composition Lather profile (ml at 30 FH) Color migration to surface efflorescence Volatile material loss (fragrance and moisture)
Present invention 350 NO NO <0.5%
Normal opaque soap 350 YES YES >5%

Example 6: Comparative data to show that desired effect is achieved when hydrophilic to hydrophobic material ratio is from 10:1 to 20:1 in the coating composition (sample B).
Table 4

Examples A [working example] B [working example] C[Non-working example] D[Non-working example]
Hydrophobic to hydrophilic ratio 16:1 20:1 16.9:2.5 26:1
Summation of Film forming polymer and structurant 6 % w/w 6 % w/w 2.5 % w/w 9 % w/w
S. No. Ingredients Wt% Wt% Wt% Wt%
1 Surfactant 48.45 44.45 48.05 38.45
2 Free Fatty Acid (C16-C18) 7 7 7 7
3 Film forming polymer (High Mw) 2 2 0.5 4
4 High molecular weight PEG (4000-8000) 2 4 2.4 5
5 Metal oxides (TiO2, ZnO) 0.5 0.5 0.5 0.5
6 Salt 0.5 0.5 0.5 0.5
7 Solvent 0.5 0.5 1.5 0.5
8 Solid paraffin wax 8 10 10 12
9 Structurant (Modified starch, methyl cellulose) 4 4 2 5
10 Soap 25 25 25 25
11 Preservatives 0.05 0.05 0.05 0.05
12 pH regulator 0.3 0.3 0.3 0.3
13 Color / Fragrance / Emotive 1.2 1.2 1.2 1.2
14 Aqua 0.5 0.5 1.0 0.5
Observation Proper coating achieved and good barrier property Proper coating achieved and good barrier property No proper coating achieved and poor barrier property In-use lather very less. Barrier property retained.

Example 7: Comparative data on stability at high temperature as illustrated in figure 2.

Table 5

Composition Whiteness index (L* value)
Before exposure to 900C After 16 hours exposure to 900C
L* value Observation L* value Observation
Present invention 92 No spot observed on the surface of soap 91.5 No spot observed on the surface of soap
Normal opaque soap 92 No spot observed on the surface of soap 89 White/brownish spot observed

Example 9: Comparative data to demonstrate the property of effective binding of the conventional opaque soap bar and the coating soap formulation of the present invention.

Table 6

Binding properties Immediate (within 24 hrs of manufacturing) Within 30 days More than 30 days
Binding properites of soap (Example A , Table 4) stored in box [working example] Good Good Good
Binding properites of soap (Example A , Table 4) stored outside box [working example] Good Good Good
Binding properites of soap (Example A , Table 4) during use [working example] Good Soap coating remains during use NA
Binding properites of soap (Example C , Table 4) stored in box [Non-working example] Good Moderate binding Coated layer gets separated
Binding properites of soap (Example C , Table 4) stored outside box [Non-working example] Good Moderate binding Coated layer gets separated
Binding properites of soap (Example C , Table 4) during use [Non-working example] Good Soap coating gets separated from parent soap NA