CLIAMS:We claim:

1. A cleansing bar coated at least on one side with a water resistant film, the water resistant film comprising:
- nitrocellulose based lacquer;
- a viscosity modifying agent;
wherein, the lacquer and the viscosity modifying agent are mixed in a ratio such that the viscosity of the resultant mixture is from 30 cP to 1500 cP.

2. The cleansing bar as claimed in claim 1, wherein the nitrocellulose based lacquer has a melting point less than 0oC.

3. The cleansing bar as claimed in claim 1, wherein the viscosity modifying agent has a melting point less than 0oC

4. The cleansing bar as claimed in claim 1, wherein the viscosity modifying agent is selected from the group consisting of acetate esters and ketones, dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, tricresyl phosphate, and triphenyl phosphate or any combination thereof.

5. The cleansing bar as claimed in claim 1, wherein the viscosity of the resultant mixture of Nitrocellulose based lacquer and the viscosity modifying agent is preferably between 50cP to 1000cP and most preferably, between 50 cP to 800 cP at 25oC.

6. The cleansing bar as claimed in claim 1, wherein said water resistant coating optionally comprises 0.005 to 10 % by wt., of an antimicrobial agent.

7. The cleansing bar as claimed in claim 1, wherein the bar is coated on all sides with a water resistant film.

8. The cleansing bar as claimed in claim 1 having a composition comprising:
- surfactant, in the range of 1-20% by wt., selected from anionic, cationic, zwitterionic or nonionic class of surfactants or any combination thereof;
- water resistant film in the range of 0.05 to 5% by wt.;
- up to 35% of alkaline material, selected from the class of alkaline and alkaline earth metal, hydroxide, carbonate, silicate or any combination thereof.
- water insoluble or sparingly water soluble material, in the range of 35-60% by wt.;
- up to 15% by wt. of water;
- 0.01-2% by wt. of an antimicrobial agent, enzyme, optical brighter, perfume, sequestrant or any combination thereof.

9. A process of applying the water resistant film on the cleansing bar, comprising the steps of:
- maintaining the temperature of the cleansing bar between 50 to 90oC;
- mixing the Nitrocellulose based lacquer and the viscosity modifying agent in a ratio such that the viscosity of the resultant mixture is from 30 cP to 1500 cP;
- applying at least one coat of said mixture/film to the bar by spraying, brushing, dipping or sponge stamping; and
- curing the film, which is assisted by said maintained temperature.

10. The process as claimed in claim 9, wherein preferably the temperature of the cleansing bar is maintained between 50 to 80oC and most preferably between 50 to 70oC.

11. The process as claimed in claim 9, wherein the viscosity of the resultant mixture of Nitrocellulose based lacquer and the viscosity modifying agent is preferably between 50cP to 1000cP and most preferably between 50 cP to 800 cP at 25oC.

12. The process as claimed in claim 9, wherein multiple coats of the mixture/film are applied to the bar.

13. The process as claimed in claim 9, wherein, the step of curing optionally requires radiation, having a frequency less than 1015 Hertz.

14. A cleansing bar substantially as herein described with reference to the foregoing description and examples.

15. A process of applying the water resistant film on the cleansing bar substantially as herein described with reference to the foregoing description and examples.

Dated this 26TH day of April 2013

of ANAND & ANAND, Advocates
Agents for the Applicants ,TagSPECI:“A cleansing bar”

FIELD OF THE INVENTION

The present invention relates to a cleansing product which is in the form of a bar. More particularly, the cleansing bar is coated at least on one side with a water resistant film.

BACKGROUND OF THE INVENTION:

Objects such as detergent bar are in constant touch with water, due to which they produce mush or become soggy. This leads to fast wear and poor ease of application. The shape and contour of the bars is not retained satisfactorily, as the sogginess causes the bar to disintegrate to paste form.

The sogginess and the mush formation also cause actives such as antibacterial molecules to be released easily and get wasted.

Conventionally, the solution provided for this problem is by altering the composition of the cleansing bar itself. However, this does not effectible address the problem of mush formation or sogginess when the cleansing bar is in constant touch with water.

US patent US2007912996A provides the preparation and the method of making the detergent bar and also forms the solid film on the detergent material. It uses water soluble polymer material membrane.

Indian patent application no. 3/Mum/2010 teaches a long lasting soap-cake. The patent employs a scrubber to make the soap insoluble in water. It does not teach any water resistant film to be applied on the soap.

Indian application no. 272/Mum/2005 describes a protective layer incorporated with soap or detergent or surfactant. However, the protective layer is a water soluble film made up of film forming materials like polyvinyl alcohol copolymer ionomers, polyvinyl alcohol homopolymer.

Indian patent application no. 310/Mum/2003 describes a bar soap having a polypropylene laminate film which is wrapped laterally around it. It deals with the concept of soap wrappers.

The prior art also teaches Radiation and photo-curable polymer films. U.S. Patent No. 6,284,835, teaches high impact coatings exhibiting resistance to impact damage. The composition is formulated with a combination of poly-functional and mono-functional ethylenically unsaturated monomers, oligomers and polymners. The cured coatings prepared by this patent exhibit superior abrasion resistance, adhesion and color retention upon prolonged exposure to UV radiation.

US patent 7,012,057 relates to detergent bars, wherein the external surface of said shaped detergent composition is coated with a polymer film obtained by radiation curing of a radiation-curable resin composition. The external surface of the detergent bar is coated with UV cured polymer. It requires elaborate radiation arrangements for curing. Moreover, UV radiation can also be harmful and is not cost efficient.

Hence, none of the prior art teaches the water-resistant film coating for cleansing bar that is the subject matter of this disclosure. Therefore, it is desired that the cleansing bars should possess acceptable physical strength so that they retain their structural integrity during handling, transport and use and at the same time they are safe and economical to manufacture.

SUMMARY OF THE INVENTION

Therefore, the objective of the present disclosure is to obviate the above drawbacks.

Further objective of the present disclosure is to provide a cleansing bar coated with a water resistant film.

Further objective of the present disclosure is to provide a coated cleansing bar that is durable even when in prolonged contact with water.

Another objective of the present disclosure is to provide a process of coating the bar with a water resistant film.

Yet another objective of the present disclosure is to provide a water resistant coating for the cleansing bar which is air curable or self-curable.

Accordingly, the present disclosure provides a cleansing bar coated at least on one side with a water resistant film. The water resistant film comprises nitrocellulose based lacquer with a viscosity modifying agent. The lacquer and the viscosity modifying agent are mixed in a ratio such that the viscosity of the resultant mixture is from 30 cP to 1500 cP.

The said coating composition is air curable or self-curable. The coating is applied to the cleansing bar either by spraying, brushing, dipping or sponge stamping, while maintaining the temperature of the cleansing bar between 50 to 90oC.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present disclosure will now be described in detail with reference to the examples. However, the present disclosure is not limited to the embodiments. The present disclosure can be modified in various forms. Thus, the embodiments of the present disclosure are only provided to explain more clearly the present disclosure to the ordinarily skilled in the art of the present disclosure.

According to an embodiment of the present disclosure a cleansing bar is coated with a water resistant film. The water resistant film comprises of nitrocellulose based lacquer mixed in a solvent to obtain the desired viscosity. The coating is applies on all or at least one side of the cleansing bar.

The lacquer and the viscosity modifying agent are mixed in a ratio such that the viscosity of the resultant mixture is from 30 cP to 1500 cP. More preferably, the viscosity of the resultant mixture is from 50 cP to 1000cP and most preferably, from 50 cP to 800 cP at 25 C.

The nitrocellulose based lacquer and the viscosity modifying agent has a melting point less than 0oC. The viscosity modifying agent may be selected from the class of molecule such as, acetate esters (eg, ethyl, butyl, or propyl acetate) and ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone), dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, tricresyl phosphate, and triphenyl phosphate or any combination thereof.

The water resistant coating may optionally comprise of 0.005 to 10 % by wt., of an antimicrobial agent.

According to another aspect of the present embodiment, the cleansing bar composition may comprise of:
- surfactant, in the range of 1-20% by wt., selected from anionic, cationic, zwitterionic or nonionic class of surfactants or any combination thereof;
- water resistant film in the range of 0.05 to 5% by wt.;
- up to 35% of alkaline material, selected from the class of alkaline and alkaline earth metal, hydroxide, carbonate, silicate or any combination thereof.
- water insoluble or sparingly water soluble material, in the range of 35-60% by wt.;
- up to 15% by wt. of water;
- 0.01-2% by wt. of an antimicrobial agent, enzyme, optical brighter, perfume, sequestrant or any combination thereof.

According to yet another aspect of the present embodiment, at least one coat of the water resistant film may be applied to the cleansing bar by spraying, brushing, dipping or sponge stamping, while maintaining the temperature of the cleansing bar between 50 to 90oC. Preferably, the temperature of the bar is maintained between 50 to 80oC and most preferably, between 50 to 70oC. Multiple coats of the mixture/film may also be applied to the bar.

Thereafter, the film is self cured with the help of maintained temperature. The drying or the curing time of coating at the maintained temperature is up to 6 seconds. This is desirable for the packing, since bar should not be sticky to the wrapper. The present disclosure eliminates the use of any special radiation/arrangements/ harm full radiation like UV or need of any catalyst for fast curing, as described in the prior art. Curing / drying can also be done in the dark where no light is present. The coating described in the present invention is flexible and doesn’t develop cracks during transportation or during use, which is a common problem with hard films. Also the coating in the present invention has a very transparent appearance which doesn’t change the color of the coating sides and thus maintain the integrity/aesthetic of the product.

Optionally, even if the step of curing requires radiation, it has a frequency less than 1015 Hertz.

The below table 1 mentions the examples of coating on a cleansing bar product and other relevant parameters.

Coating material Method of application Solvent Lacquer to solvent ratio viscosity Temperature
of the bar during coating Curing time Ex
Nitrocellulose based lacquer spray Acetone 1:0.5 ~600 cP 25 2 min 1
Nitrocellulose based lacquer spray Acetone 1:0.5 ~600 cP 70 6 sec 2

Table 1

The below Table 2 further describes non-limiting specific examples of coating composition, according to one of the embodiments of the present disclosure.

Bar L-mm Bar W-mm Bar H-mm Bar Area covered- cm2 coating V-cm3 Thickness -mm Bar No. Bar Wt before coating gm Bar Wt. after coating gm No. of Coats Gm of coated material wt% of coated material over bar coating Effective-ness against water in hrs/min ratio laquer / thinner
93 53 16 9.601 NA NA C1 131.9026 NA NA NA NA 2 mins NA
89 53 16 9.261 0.132472 0.14 1 132.8021 132.9200 1 0.1179 0.09 48+ hrs 1:1
94 53 16 9.686 0.149551 0.15 2 131.1105 131.2436 1 0.1331 0.10 48+ hrs 1:1
90 53 16 9.346 0.124494 0.13 3 130.3052 130.4160 1 0.1108 0.09 48+ hrs 1:1
89 53 16 9.261 0.365169 0.39 4 129.4012 129.7262 2 0.3250 0.25 48+ hrs 1:1
95 53 16 9.771 0.402697 0.41 5 136.8656 137.2240 2 0.3584 0.26 48+ hrs 1:1
93 53 16 9.601 0.381573 0.40 6 131.5930 131.9326 2 0.3396 0.26 48+ hrs 1:1
89 53 16 9.261 0.329326 0.36 7 133.9419 134.2350 1 0.2931 0.22 48+ hrs 2:1
89 53 16 9.261 0.419101 0.45 8 136.1455 136.5185 1 0.3730 0.27 48+ hrs 2:1
95 53 16 9.771 0.300225 0.31 9 127.1426 127.4098 1 0.2672 0.21 48+ hrs 2:1
89 53 16 9.261 0.773034 0.83 10 122.8538 123.5418 2 0.6880 0.56 48+ hrs 2:1

Table 2

Further, Table 3 is included to demonstrate the effectiveness of the cleansing bar coated with the present water resistant film in a manner as herein described. Two bars of same size and weight (~200 gms each), one being coated with the present water resistant film and the other without said film were put into water, such that the all the surfaces are in the water and only the top surface of the bar is exposed to air. Mush formed is noted down by removing the bars and taking their weights at different time interval.

Mush formed
20 min 3 hrs 5 hrs 24 hrs 5 days
Coated bar as In Ex-2 0 0 0 0 0
Uncoated bar ~5 gm ~10 gm ~20 gm ~75 gm ~140 gm

Table 3: Mush formation in contact with water

The coated bar showed no mush formation even though it was in constant contact with water. Hence, the present disclosure solves the problem of sogginess or the mush formation of a cleansing object, such us detergent bar or tablet, which are in constant contact with water. It also gives an economical and safe process of applying a water resistant film on it.

It also gives a better aesthetics to the bar by giving gloss to its surfaces. Additionally, the coating can also be used as a medium of delayed release of actives such as antibacterial molecules. The process and the composition can be used to make dish wash bar, bathing soap or hard surface cleaner and fabric wash bar.

While the disclosure is described in conjunction with the illustrated embodiment, it will be understood that it is not intended to limit the disclosure to such embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.

In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.