WO2008113973A1

WO2008113973A1 - Applicator, kit and process

Info

Publication number: WO2008113973A1
Application number: PCT/GB2008/000827
Authority: WO
Inventors: Diane Kelly
Original assignee: Reckitt Benckiser (Uk) Limited
Priority date: 2007-03-20
Filing date: 2008-03-10
Publication date: 2008-09-25
Also published as: GB0705300D0

Abstract

An applicator for delivering a depilatory composition to a surface (e.g. skin), comprises a friable polymeric solid and a liquid or gel treatment composition contained within the solid such that rubbing the applicator on a surface breaks down the solid and releases the liquid or gel. A process for creating the applicator involves impregnation of the treatment composition into the solid by use of supercritical or superheated fluid. The applicator may be incorporated into a holder to facilitate use.

Description

APPLICATOR, KIT AND PROCESS

The invention is concerned with an applicator for delivering a liquid to a surface and a process for its manu- facture. In particular it is concerned with a friable polymeric solid containing a liquid or gel treatment composition, such as a depilatory composition, which is rubbed against a surface (such as skin) and releases the liquid or gel as the friable polymeric solid is eroded or crumbles away.

Sponges are known in the art and may be in the form of either closed or open cell solid matrices. Actual sponges are solid matrices formed from the exoskeletons of living sponges, and these have been mimicked by synthetic sponges made from solid polymeric materials. It is known to impregnate such sponges with a clean solution and then to apply the solution to a surface to be cleaned. The cleaning solution or liquid is absorbed into voids in the sponge when applied by the user from a separate source of cleaning solution or liquid, and then is squeezed out of the sponge in use when applied to a surface. This process leads to the liquid often coming into contact with the hands of the user necessitating the use of protective gloves. Cleaning liquid may also be wasted in that it permeates into parts of the sponge which are not subsequently used during the immediate cleaning process. Moreover, the sponge must be squeezed and emptied of the cleaning , fluid after use in order to prevent its leakage onto any surfaces ^N where the sponge- may be stored subsequently. Furthermore, the sponge requires a separate source of cleaning solution or liquid. In order for such sponges to function the cells making up the matrix of the sponge must be interconnected such that liquids can pass from the outside of the sponge into the cells and then re-pass from the interior cells to the outside when required by the user, initiated by squeezing the sponge to close the cells and eject the cleaning liquid.

US 4,476,251 discloses a polyurethane foam having cleaning and germicidal activities. The foam is prepared by mixing together a pre-polymer reactant and water and adding to the mixture, prior to foam formation, a non- ionic surfactant, a quaternary ammonium compound and a silicone based surfactant. The foam is recommended as a disposable wiping pad to household cleaning applica- tions.

US 3,283,357 discloses and disinfecting cleansing pad, where a disposable pad or sponge incorporates a substantially dry water soluble impregnant consisting of a ger- micidal quaternary ammonium compound and amphoteric surfactants which are activated by moistening the pad or sponge immediately prior to use.

WO98/59026 discloses and cleaning material for cleansing surfaces comprising a closed cell foam matrix including an antimicrobial composition. The foam matrix may be a polyurethane foam and the antimicrobial composition may comprise silver ions in the form of a combination with a support material such as titanium dioxide. The silver halide/titanium dioxide is incorporated into the closed cell foam as a solid. It has now been found that problems of the prior art can be overcome by use of a friable polymeric solid, which has a liquid or gel cleansing composition contained within the friable polymeric solid.

In a first aspect the invention provides an applicator for delivery of a depilatory composition to a surface (e.g. skin) comprising a friable polymeric solid and a liquid or gel treatment composition characterised in that the liquid or gel treatment composition is contained within the friable polymeric solid whereby rubbing the applicator on a surface leads to breakdown of the friable polymeric solid and release of the liquid or gel treatment composition to the surface.

In use the applicator is rubbed against a surface to which it is desired to deliver a liquid or gel treatment composition. As the friable polymeric solid crumbles and breaks away from the body of the applicator, the liquid or gel treatment composition contained within the friable polymeric solid is released onto the surface to be treated. Preferably the applicator is used on skin surfaces such as legs, chests and intimate areas. Because the closed cells are impermeable to the liquid or gel treatment composition, the liquid or gel does not come into contact with the user where the applicator is held by the user, but is only released where the friable polymeric solid breaks down on contact with the surface.

The friable polymeric solid is preferably a polymeric foam matrix comprising voids enclosed or partially enclosed by solid friable walls. The polymeric foam matrix may be an open cell foam, where the voids are in fluid connection, or may be a closed cell foam.

By closed cell it is meant that at temperatures from 0° to 40° centigrade and atmospheric pressure, the cells are not permeable to the flow of liquid from one cell to the next, such that if one cell contains liquid or gel, the leakage of that liquid or gel into adjacent cells is negligible.

Suitably, the polymeric foam matrix may comprise both open and closed cells. Preferably, the polymeric foam matrix is substantially a closed cell foam matrix.

The polymeric foam matrix is preferably made from a friable polymeric material such as polyurethane, polyester, polyether, melamine or expanded polyethylene. Suitable polymeric foams include polyurethane foam and floral foam as supplied by Trident Foams Ltd UK and expanded polyethylene foam as supplied by Custom Foams UK.

The void diameter in the polymeric foam is suitably 1 nm to 0.5 cm, preferably 1 Dm to 0.3 cm. The thickness of the polymeric foam matrix between the voids is suitably from 100 nm to 0.5 cm, preferably IDm to 0.3cm

The friable polymeric solid may also suitably be in the form of a single phase friable polymeric solid without voids, such as exemplified by a pencil eraser. A suit- able polymer for this purpose is polyvinyl chloride.

In use, the surface to be treated is rubbed with the applicator, and it is particularly preferred for the fri- able polymeric solid to be of such a friability that it tends to wear away to a limited extent when being rubbed on the surface. Moreover, the fine mildly abrasive par- tides formed as the friable polymeric solid crumbles in use also provide the benefit of aiding in removal of soil from the surface by abrasion.

A test for friability is as follows. A cube of the friable polymeric material containing the liquid or gel composition (35mm x 35mm x 35mm) is weighed. The cube is pushed down on to a sandpaper surface (3M™ P60 245 grade) with an applied force of 55Og and wiped over a 15 cm length course for 10 wipes. The cube is reweighed to measure weight loss. The range of suitable friability is from 1% to 50% weight loss. ^'

The friability is to be measured after incorporation of the liquid or gel composition, as this may modify the friability of the polymeric material from its staring friability.

The friability can be adapted for suitability to the specific applications e.g. higher friability for use on soft materials.

The treatment composition is preferably an aqueous liquid or gel composition, by which is meant that the composition comprises from 40 to 98% by weight of water, preferably from 50 to 95% by weight of water.

Suitably the cleansing composition comprises an active depilatory agent selected from the group consisting of an alkali metal salt or alkaline earth metal salt of an alpha or beta mercapto-carboxylic acid, such as potassium or calcium thioglycolate. (The potassium thiogly- colate can be made in situ from thioglycolic acid and KOH or can be added as pre-formed potassium thioglyco- late) . Indeed typically, an alkali / alkaline hydroxide (e.g. KOH, Ca(OH)₂) is added to raise the pH of the system and swell the hair.

The bleaching composition contains a bleaching agent such as hydrogen peroxide, preferably in an amount of from 1 to 50% by weight, more preferably from 3 to 6% by weight .

Other compatible, conventional ingredients may also be incorporated in the cleansing composition, such as surfactants, solvents, acids, buffers, builders, seques- trants, chelating agents, gelling agents, fragrance, viscosity modifiers, preservatives and antimicrobials.

In one embodiment of the invention, the applicator is in the form of a block suitable to be grasped in the hand,or preferably shaped to fit the hand. During use the end of the applicator that wears away by rubbing the surface being cleaned, takes the shape of the contours of the surface being cleaned, enabling awkward nooks, crannies and corners to be cleaned with greater facility.

Another aspect of the invention concerns a kit of parts comprising an applicator as detailed above and a holder for the applicator wherein the applicator is removably but firmly held within the holder. The applicator is suitably adapted to be grasped in the hand of the user. A preferred embodiment of this aspect of the invention is where the kit has the appearance and characteristics of a dry-stick deodorant device, whereby the applicator device can be progressively extruded from the opening of the holder by the user using means conventionally employed in dry-stick deodorant devices (pushing up the base or rotating the base to feed the applicator out of the holder) .

The application in use may become coloured at the end applied to a surface. Accordingly the kit may also comprise a cutter to remove the coloured part of the applicator before it is reused.

In another aspect, the invention provides a suitable process for incorporating the liquid or gel treatment composition into the friable polymeric solid comprises the following sequential steps:

i) forming a friable polymeric solid into the shape of the applicator,

ii) placing the friable polymeric solid in a pressure vessel,

iii) impregnating the friable polymeric solid with the liquid or gel treatment composition at elevated temperature and pressure within the pressure vessel, and

iv) removing the friable polymeric solid impregnated with the liquid or gel treatment composition from the pressure vessel. Alternatively, the step (i) of forming the friable polymeric solid into the shape of the applicator may take place after steps (ii) to (iv) .

Thus, the invention also provides a process for forming an activator comprising the steps of:

i) placing a friably polymeric solid in a pressure vessel,

ii) impregnating the friable polymeric solid with a liquid or gel treatment composition at elevated temperature and pressure within the pressure vessel,

iii) removing the friable polymeric solid impregnated with the liquid or gel treated composition from the pressure vessel, and

iv) forming the impregnated friable polymeric solid into the shape of the applicator.

A suitable elevated temperature is, for example, at least 50⁰C, preferably at least 60⁰C, more preferably at least 8O⁰C. A suitable elevated pressure is, for exam- pie, at least 2 bar (200 kPa) , preferably at least 3 bar

(300 kPa) , more preferably at least 5 bar (500 kPa) .

Advantageously the friable polymeric solid is impregnated with a liquid or gel treatment composition by use of a supercritical or superheated liquid. By supercritical fluid is meant a substance at a temperature and pressure above the critical temperature and pressure of the fluid.

A preferred supercritical fluid for use in the process of the invention is carbon dioxide.

By superheated fluid, is meant a fluid which is heated to a temperature higher than its boiling point, without boiling, by maintaining it at a pressure higher than atmospheric pressure. It is preferred to use superheated water/steam in the process of the invention, at a pressure of 3 Bar or more, preferably 10 bar or more.

Without wishing to be bound by any scientific theory, it is thought that the supercritical or superheated fluid leads to increased permeability of the friable solid polymer such that the treatment composition can diffuse through the swollen polymer to become entrained within the polymer itself and/or within any voids in the solid if the solid is a polymeric foam.

Claims

1. An applicator for delivery of a depilatory composi- tion to a surface (e.g. skin), comprising a friable polymeric solid and a liquid or gel treatment composition, characterised in that the treatment composition is contained within the friable polymeric solid whereby rubbing the applicator on a surface leads to breakdown of the friable polymeric solid and release of the treatment composition to the surface.

2. An applicator according to claim 1, wherein the friable polymeric solid is a polymeric foam.

3. An applicator according to any preceding claim wherein the friable solid is a closed cell polymer foam.

4. An applicator according to any preceding claim wherein the treatment composition comprises an active depilatory agent such as an alkali metal salt or alkaline earth metal salt of an alpha or beta mercapto- carboxylic acid, such as potassium or calcium thioglyco- late.

5. An applicator according to any preceding claim wherein the treatment composition comprises an alkali / alkaline hydroxide (e.g. KOH, Ca(OH)₂) is added to raise the pH of the system and swell the hair.

6. An applicator according to any preceding claim wherein the treatment composition comprises a • compound selected from the group consisting of surfactants, sol- vents, acids, buffers, builders, sequestrants, chelating agents, gelling agents, fragrance, viscosity modifiers, preservatives and antimicrobials or mixtures thereof.

7. A kit of parts comprising an applicator as claimed in any preceding claim and a holder for the applicator wherein the applicator is removably but firmly held within the holder.

8. A process for forming an applicator as defined in any one of claims 1 to 6 comprising the steps of:

i) forming a friable polymeric solid into the shape, of the applicator,

ii) placing the friable polymeric solid in a pressure vessel,

iii) impregnating the friable polymeric solid with a liquid or gel treatment composition at elevated temperature and pressure within the, and

iv) removing the friable polymeric solid impregnated with the liquid or gel treatment composition from the pressure vessel.

9. A process for forming an applicator as defined in any one of claims 1 to 6 comprising the steps of:

i) placing a friable polymeric solid in a pressure vessel, ii) • impregnating the friable polymeric solid with a liquid or gel treatment composition at elevated temperature and pressure within the pressure vessel,

10. A process according to claim 8 or claim 9 wherein the friable polymeric solid is impregnated with the liquid or gel treatment composition by use of a supercriti- cal or superheated fluid.

11. A process according to claim 10 wherein the supercritical fluid is carbon dioxide.

12. A process according to claim 11 wherein the superheated fluid is water.