EP4753653A1

EP4753653A1 - A personal cleansing tablet

Info

Publication number: EP4753653A1
Application number: EP24748954.5A
Authority: EP
Inventors: Saswati PUJARI; Manisha Prashant KHARKAR; Dev Raj; Swathi SRINIVASAN
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Priority date: 2023-08-03
Filing date: 2024-07-26
Publication date: 2026-06-10
Also published as: MX2026001027A; CN121729209A; WO2025026931A1

Abstract

The present invention relates to a skin cleansing tablet composition that is high in surfactant yet disintegrates and completely dissolves quickly to form a cleansing solution that can be used by the consumer over time. This is achieved through a tablet comprising sodium lauryl sulphate as the surfactant together with a specific polymer viz. polyvinyl pyrrolidone with defined low molecular weight and an excipient chosen from maltodextrin or sorbitol.

Description

A PERSONAL CLEANSING TABLET

Field of the Invention

The present invention relates to a personal cleansing tablet composition. It more particularly relates to a tablet composition that is high in surfactant yet disintegrates and completely dissolves quickly to form a cleansing solution that can be used by the consumer over time.

Background of the Invention

People use skin cleaning compositions to keep the external surface of their bodies clean, hygienic, and free of malodour. Such compositions are available for body wash, face wash, hand wash and for washing hair (usually called shampoos). They are available in various formats. The most traditional format is that of a bar. To be able to deliver products that are milder on skin, they are formulated as liquids which have been more preferred of late. Liquid products are packaged in bottles and such products contain high amount of water which have to be transported over long distances. Therefore, there is a need for developing more environmentally friendly products.

One such environmentally friendly format is a tablet. Tablets contain minimum amount of water and can be delivered with very less amount of packaging thereby making it a more environmentally sustainable solution. Tablets however suffer from the problems of slow disintegration and incomplete dissolution. The present inventors set out to develop a skin cleansing tablet that contains high amount of surfactant thereby ensuring good cleaning while at the same time disintegrating quickly and dissolving completely in matter of minutes in water. The cleansing solution, so prepared can be stored in a container and used by the consumer over a period of time.

Tablet compositions for skin cleaning have been disclosed in the past. US2020/0345590 (Earthsuds) discloses a cleansing tablet comprising a surfactant, moisturizing agent and a thickening agent which is claimed to disintegrate quickly. US2003/0153582 (Mumoli) discloses a single-dose quick dissolving cleansing composition which comprises a surfactant, a first and second disintegrating agents combined for causing a sudden disintegration and dissolution of the agent upon contacting the agent with a liquid medium. The first disintegration agent is a polymer and the second disintegrating agent may be a microcrystalline cellulose.

The products disclosed in the above patent publications use agents like tapioca starch or microcrystalline cellulose that do not dissolve in water completely thereby giving a product with suspended solids. The present inventors were looking to develop a product that dissolves completely in water with no residual undissolved solids. The present inventors have achieved this through use of a tablet composition comprising high amount of a sodium alkyl sulphate surfactant together with a specific polymer viz. polyvinyl pyrrolidone with defined low molecular weight and an excipient chosen from maltodextrin or sorbitol.

It is thus an object of the invention is to provide for a tablet composition that comprises high amount of surfactant that disintegrates and dissolves in water very quickly.

Summary of the Invention

The present invention relates to a personal cleansing tablet comprising,

(i) 50 to 95 wt% sodium alkyl sulphate with the alkyl group having 8 to 14 carbon atoms;

(ii) 1 to 30 wt% polyvinyl pyrrolidone having a molecular weight in the range of 2000 to 80,000 Da; and

(iii) 3 to 20 wt% an excipient selected from maltodextrin or sorbitol; wherein the polyvinyl pyrrolidone is not crosslinked

Detailed Description of the Invention

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from reading of the following detailed description. 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 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.

By “high in surfactant” is meant a composition as per the invention in tablet form that comprises higher than 50% total amount of surfactant, preferably from 50 to 90% surfactant by total weight of the tablet. By “disintegration time” as per this invention, is meant the time taken for the tablet to break apart into smaller pieces when added to water, as measured by visual observation.

By “dissolution time” is the time taken for the tablet to completely dissolve in water, as measured by visual observation.

By “water insoluble” is meant any ingredient that is not fully soluble in water resulting in suspended solids or precipitates over time, which can be noticed by visual observation. By an “excipient” as per this invention is meant ingredients other than the surfactant, that is added to the tablet to perform specific tasks such as binding, aiding in disintegration/ dissolution, or remain inert merely as a filler.

The tablet as per this invention comprises 50 to 95 wt%, preferably 65 to 80 wt%, more preferably 65 to 75 wt% sodium alkyl sulphate with the alkyl group having 8 to 14 carbon atoms. Preferably higher amount of surfactant is used as it gives better cleaning performance. The preferred sodium alkyl sulphate is sodium lauryl sulphate. Sodium lauryl sulphate is available in solid form as Galaxy 689 (Galaxy Surfactants), Sodium dodecyl sulfate (Sigma Aldrich), Sodium Lauryl Sulfate (KLK Oleo, Thermo Fisher Scientific, SRL Pharma), STEPANOL® WA-100 NF/USP (Stepan). It has been found by way of this invention that sodium alkyl sulphate at this concentration is unique in its ability along with the other ingredients claimed to deliver the desired low disintegration time and dissolution time. The inventors experimented with various other commercially available surfactants like cocoamidopropyl betaine, potassium cocoyl glycinate, sodium cocoyl glycinate, sodium lauryl glutamate, disodium lauryl sulphosuccinate, sodium cocoyl glutamate, and sodium cocoyl isethionate and none of them were able to deliver the desired disintegration and dissolution profile.

The tablet composition of the invention includes a polymer which is specifically chosen to be polyvinyl pyrrolidone (PVP) having a molecular weight in the range of 2000 to 80,000 Da, preferably in the range of 2000 to 55,000 Da, further more preferably in the range of 2000 to 30,000 Da. The present inventors experimented with various other polymers like Crospovidone, Polyethylene Glycol, Sodium Starch Glycolate, Croscarmellose Sodium and polyvinyl alcohol but found them unsuitable to meet the object of the present invention. Crospovidone is a cross linked poly vinyl pyrrolidone. It is insoluble in water. Since the present invention requires that the polymer not only disintegrates quickly it also dissolves completely in water, Crospovidone was found not to be suitable for use in the present invention. Thus, the polyvinyl pyrrolidone for use in the present invention is preferably not cross-linked. It is especially preferred that the tablet composition comprises less than 0.1 wt% water insoluble polymer. It is further preferred that the tablet composition comprises less than 0.1 wt% cross-linked polymer e.g. Crospovidone. Even within polyvinyl pyrrolidone, only the lower molecular weights as claimed worked to solve the problem while those having higher molecular weights were found wanting in terms of disintegration and/ or dissolution. The desired PVP are available as Kollidon 12PF (from BASF), Kollidon 17PF (from BASF), PVP 10 (from Sigma), Kollidon 25 (from BASF), PVP 234257 (from Sigma), PVP K30 (Unilong Industries), PVP 40 (Sigma), and PVP 856568 (Scientific Laboratory). The tablet comprises the PVP having the desired molecular weight to be included in 1 to 30 wt% preferably 3 to 20 wt%.

The tablet composition includes an excipient selected from maltodextrin or sorbitol. Of the two maltodextrin is more preferred as it delivers the desired disintegration does not adversely affect the lathering obtained from the cleansing composition, during use. The excipient is included in 3 to 20 wt%, preferably 5 to 15% by weight of the tablet composition. It is preferred that the weight ratio of the PVP to the excipient is in the range of 4:1 to 1 :4. Using materials within this ratio range ensures that the table disintegrates and dissolves within the desired time frame.

It is preferred that the tablet composition as per the invention includes not more than 1 wt%, preferably not more than 0.1 wt% water insoluble ingredients. More preferably the tablet composition comprises less than 0.1 wt% water insoluble ingredients. Ideally no water insoluble ingredient is included. Water insoluble ingredients as per this invention includes materials like cellulose, starch, microcrystalline cellulose, clay, crosslinked polymers and hydrated aluminosilicate materials like zeolite. This ensures that the tablet dissolves fully in water with a clear and transparent/ translucent solution with no sediment formation.

The tablet of the composition preferably does not comprise an effervescent system. Effervescent systems have generally been used to expediate dissolution of tablets. Effervescent system generally comprises an organic acid and a carbonate or bicarbonate salt. When the tablet with an effervescent system comes in contact with water the acid and the alkali react to generate bubbles of carbon di oxide which help in disintegrating the tablet. It is especially preferred that such an acid and alkali which can form an effervescent system is present in not more than 1 wt%, preferably not more than 0.1 wt% and ideally is absent from the tablet composition of the present invention.

The table composition may comprise certain other ingredients like colour, perfume, preservative, and chelating agent to deliver these additional properties. As per the present invention the composition of the tablet is generally preparing by mixing the surfactant and the above ingredients like colour/ pigment, perfume, preservative, and chelating agent as a premix. The premix preferably comprises surfactant in about 85 to 95 wt%, perfume in about 0.1 to 2 wt%, preservative from 5 to 10 wt% and chelating agent from 1 to 3 wt%. The premix generally accounts for about 70 to 85wt%, preferably 75 to 82 wt% of the composition. The desired amount of premix is then mixed with the PVP and the excipient in a suitable powder mixer and then tableted. The tableting is done using a compaction pressure which is normally used in the art. The tablet composition is generally delivered in from 1 to 15 grams preferably 8 to 12 grams. The tablet may be prepared in various shapes like disc, rectangular, square, and rodlike. When in use the tablet is dissolved in water at a dilution ratio of tablet: water preferably in the range of from 1 :5 to 1 :30, more preferably 1 :10 to 1 :25. The solution so prepared may be stored in a bottle for use by the consumer several times. The solution so prepared may ideally have a viscosity in the range of 1 to 5 cps.

The present invention thus also relates to a tablet which disintegrates in less than 3 minutes. It also relates to a tablet that dissolve completely in less than 30 minutes.

Thus, the present invention also provides for a liquid cleansing composition comprising a tablet as claimed in the present invention dissolved in water; wherein the weight ratio of the tablet to water is in the range of 1 :5 to 1 :30.

The weight ratio of the tablet to water to prepare the liquid cleansing composition is preferably in the range of 1 :10 to 1 :25.

The invention will now be illustrated with the help of the following non-limiting examples.

Examples

Examples 1-32, A- D: Effect of the type of PVP on the disintegration of tablets.

A premix was prepared by mixing the following ingredients in powder form as shown in Table - 1.

Table - 1 :

Various tablets were prepared using the compositions as shown in Table - 2 below. The disintegration time (DT) was measured as described below: The amount of water required for the tablet dissolution is taken in a container. The tablet is gently added to it, while simultaneously starting the stopwatch. The container is closed tightly with a lid and shaken for 30 seconds. After shaking, the container is kept aside until the tablet breaks apart into smaller pieces. The time taken for this is noted down as the disintegration time. The data is summarized in Table - 2 below:

Table - 2:

The data in the table above indicates that composition as per the invention (Examples 1-32) deliver good disintegration time. Using high molecular weight PVP (as in Examples A -D) causes the tablet to not disintegrate fully.

Examples 1-3: Dissolution times

Tablets prepared as per examples 1 -3 were tested for dissolution time using the following method:

The amount of water required for the tablet dissolution is taken in a container. The tablet is gently added to it, while simultaneously starting the stopwatch. The container is closed tightly with a lid and shaken for 30 seconds. After shaking, the container is kept aside until the tablet is completely solubilized in water. The time taken for this is noted down as the dissolution time. The dissolution time is shown in table - 3 below

Table -3

The data in the table - 3 above indicates that tablets as per the invention (1-3) could dissolve completely in about 30 minutes.

Examples E-J; 33: Dissolution times

Tablets prepared as per examples E-J and 33 as shown in Table - 4 below were prepared as 10 gram tablets similar to the ones prepared in Table -1 . They were tested for dissolution time using the method described hereinbefore:

The dissolution time is shown in table - 4 below.

Table -4

PVPXL and PVPXL10 are two different grades of Crospovidone. Kollidon 12PF is polyvinyl pyrrolidone as per the invention as also used in Examples 1 to 3 in Table - 2. The data in the table - 4 above indicates that tablet as per the invention Example -33 dissolves completely in much quicker time as compared to using Crospovidone (a crosslinked PVP).

Claims

1. A personal cleansing tablet comprising

(iii) 3 to 20 wt% an excipient selected from maltodextrin or sorbitol; wherein the polyvinyl pyrrolidone is not crosslinked.

2. A tablet as claimed in claim 1 wherein the sodium alkyl sulphate is sodium lauryl sulphate.

3. A tablet as claimed in claim 1 or 2 wherein the excipient is maltodextrin.

4. A tablet as claimed in any one of the preceding claims comprising 65 to 80 wt%, preferably 65 to 75% sodium alkyl sulphate.

5. A tablet as claimed in any one of the preceding claims comprising 3 to 20 wt% polyvinyl pyrrolidone.

6. A tablet as claimed in any one of the preceding claims comprising 5 to 15 wt% excipient.

7. A tablet as claimed in any one of the preceding claims wherein the tablet comprises less than 1 % water insoluble ingredients.

8. A tablet as claimed in any claim 7 wherein the water insoluble ingredients includes microcrystalline cellulose, starch, clay, crosslinked polymers and hydrated aluminosilicate materials like zeolite.

9. A tablet as claimed in any one of the preceding claims having a weight in the range of 1 to 15 grams.

10. A tablet as claimed in any one of the preceding claims wherein the tablet disintegrates in water in less than 3 minutes.

11. A tablet as claimed in any one of the preceding claims wherein all the ingredients dissolve in water in less than 30 minutes.

2. A liquid cleansing composition comprising a tablet as claimed in any one of the preceding claims dissolved in water; wherein the weight ratio of the tablet to water is in the range of 1 :5 to 1 :30.