AU714022B2 - Aqueous solution compositions comprising polymer hydrogel compositions - Google Patents

Description

WO 98/08601 PCT/EP97/04751 1 AQUEOUS SOLUTION COMPOSITIONS COMPRISING POLYMER HYDROGEL COMPOSITIONS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to novel large hydrogel particles suspended in an aqueous medium and to a continuous extrusion/mixing process for making these kind of hydrogel particles. The hydrogel particles comprise two different high molecular weight polymers. One is insoluble in the aqueous medium and is used for network formation and gel integrity.

The other is soluble in the aqueous medium and helps control gel swelling and gel strength. Water insoluble materials are entrapped or encapsulated inside the network formed by these two polymers and are thus more efficiently delivered from the aqueous composition liquid cleanser containing the hydrogel particles). Gel particles with controllable size and controllable gel strength are prepared simply by first adding injecting) an aqueous solution containing the two polymers and the water insoluble material into the aqueous medium to form elongated soft polymer gel noodles, which noodles are then cut/broken through mixing or mechanical agitation) into desirable gel particle size.

BACKGROUND OF THE INVENTION Liquid cleansers or other compositions that can deliver skin benefit agents to provide some kind of skin benefits are desired and are known in the art. The use of silicone oil droplets to provide enhanced moisturization benefits, for example, is known.

WO 98/08601 PCT/EP97/04751 2 One method used for enhancing delivery of benefit agents silicone and vegetable oil) to the skin or hair is through the use of cationic hydrophilic polymers such as Polymer JR(R" from Amerchol or Jaguar"' R from Rhone Poulenc.

This method is disclosed, for example, in EP 93,602; WO 94/03152; and WO 94/03151. In each of these references, both the deposition polymer and the generally small sized silicone particles are uniformly distributed throughout the entire liquid cleanser composition there are no concentrated "pockets" of benefit agent).

In other references, hydrophilic polymers are themselves incorporated into liquid cleansers or aqueous solutions to provide various benefits. For example, hydrophilic polymers such as guar gum, polyacrylamides, polyacrylic acid and polymer JR'R) are disclosed in U.S. Patent Nos. 4,491,539; 4,556,510; 4,678,606; 5,002,680 and 4,917,823 as thickeners, lather modifying agents or skin feel agents. Again, in all cases, the polymers are uniformly incorporated or distributed throughout the entire surfactant composition to provide the claimed benefits.

In no reference is there taught that enhanced deposition of water-insoluble skin benefit agent from cleanser or aqueous medium, or that enhanced in-use cleanser properties by hydrophilic polymer, can be achieved using separate hydrogel particles or dispersion acting as a type of structure to contain or entrap the benefit agent in a concentrated form.

Unexpectedly, applicants have now found that, if the benefit agent is incorporated into a liquid composition in the form of an integral hydrogel carrier containing the benefit agent discrete aqueous phase trapping the benefit agent), then the level of deposition of the benefit C6360 3 agent on the skin or other substrate is significantly enhanced compared to either typical liquid or to a liquid gel composition containing a polymer agent (typically, a cationic deposition agent such as a cationic guar) to help deposit the benefit agent. The amount of deposition is also higher than for compositions having oil droplets dispersed throughout the composition in the absence of a deposition aid, particularly when small sized particles are used. Other than enhanced deposition, applicants have also found that the separate hydrogel particles enhance the cleanser's in-use sensory properties smooth and creamy feel) when the cleanser or aqueous composition generally is rubbed on the skin.

Attempts have been made in the art to deliver some beneficial material in gel particles, but none has been successful in both retaining the agent in composition while easily delivering it at end use rubbing) U.S. Patent No. 5,089,269 to Noda et al., for example, discloses a cosmetic composition containing improved gelatin capsules containing hydrophobic component coated by a gelatin film swollen with water. Previous gelatin gel or other hydrogels such as agar, alginate or carrageenan coated capsules required a strong breaking force to break the capsule to release the encapsulated ingredients. In some instance these capsules were only slid over skin surface when they were rubbed onto the skin. This patent claimed improved gelatin capsules that overcame the above non-desirable properties.

However, similar problems occurred, as described in the patent, when the improved capsule was smaller than 100 pIm or larger than 1000 ptm. The improved gel coated capsules either became too rigid to be broken or tended to escape from the fingers or palm during application. Thus, neither this or other art teaches hydrogel compositions such as that of the invention which can retain benefit agent and efficiently AMENDED SHEET C6360 4 release them as desired. Further the reference fails to teach a method of forming such hydrogel containing aqueous compositions.

EP 0,355,908 Al claims a process to make polysaccharide gel particles such as agar, carrageenan or gellan gel particles with size less than 100 )pm for food, skin lotions or cleansers applications. The document also teaches that water-insoluble substances suitable for personal care products may be included inside the gel particles. These kind of gel particles, without further modification, are again too rigid to easily break and do not provide smooth rub-in properties when the particle size is large.

U.S. Patent Nos. 4,777,089 and 4,908,233, to Takizawa, disclose microcapsule containing hydrous compositions prepared by simple coacervation process. In accordance with these patents, the capsule was prepared using two different water soluble polymers by a simple coacervation process.

Upon addition of organic or inorganic salts the first polymer phase separated and the second polymer underwent no phase separation. Without the second polymer, the first polymer failed to enclose the capsule core material or the capsule became agglomerated into a coarse mass if the capsules were formed.

In no reference is there taught that hydrogel particles can be formed using a combination of two different water soluble polymers, nor is there taught the process for making those kind of hydrogel particles.

;NDt~ED SHEET _Ilili-.II-i-l- Illill~lllX--i~i i WO 98/08601 PCT/EP97/04751 BRIEF SUMMARY OF THE INVENTION The present invention relates to aqueous compositions containing novel hydrogel particles formed by two different water soluble polymers. The hydrogel particles "trap" water insoluble beneficial agents in a network formed by these two polymers. The polymer network which entraps the benefit agents disintegrates smoothly when rubbed on a substrate such as skin in order to impart desirable in use characteristics smooth, rich, creamier feel) to the composition. More particularly, the aqueous composition comprises: 40 to 95% by wt. of an aqueous solution with viscosity higher than 300 centipoise (cps), preferably higher than 1,000 cps, more preferably higher than 3,000 cps, wherein said aqueous solutions contains 0% to 60%, preferably 2% to 40%, surfactant and wherein said surfactant, if present, is selected from the group consisting of anionic, nonionic, cationic, zwitterionic amphoteric surfactant and mixtures thereof; and 5 to 60% by wt. of a hydrogel composition comprising: 0.1 to 30% by wt. of hydrogel composition, preferably 0.3-15% of at least one polymer which is soluble in water, but which is insolubilized, ideally by thermal gelation, when placed in said aqueous solution; and (ii) 0.2 to 30%, preferably 0.5-10% by wt. of hydrogel composition of at least a second polymer which is soluble in water and either soluble or dispersible in said aqueous solution; and C6360 6 (iii) 1.0 to 60% by wt., preferably 5 to 40% by wt.

of a water insoluble beneficial agent which is entrapped in a network formed by polymers and wherein particles of said benefit agent have a particle size preferably of about 0.2 to 200 micrometers; said hydrogel preferably having a particle size in the range of from about greater than 25 micrometers, preferably larger than 100 micrometers, more preferably greater that 200 micrometers up to about several centimeters.

In one embodiment, said gel forming polymer is selected from the group consisting of gel forming polysaccharides such as carrageenan or agar, gel forming proteins, and thermally gelling synthetic polymers.

Preferably said gel forming polymer is a synthetic polymer selected from the group consisting of N-acrylamdes and homo or copolymers of polyacrylate or methacrylate containing polymers incorporating an acrylic or methacrylic ester of a long chain branched or straight chain alcohol.

Ideally the polymer of is insolubilised, when contacted with the aqueous solution of item by precipitation or coacervation, which is generally caused by a change in pH. Typically in such cases the polymer (i) will be polyglucosamine. Alternatively, precipitation or coacervation is caused by a change in electrolyte concentration. In such cases, polymer is selected from the group consisting of polyvinyl alcohol having MW greater than 13,000 and a degree of hydrolysis of from 78% to 100%; and hydroxyalkylcellulose.

Ideally, the polymer of is insolubilised by crosslinking with a cross-linker present in the aqueous solution Thus when the polymer is carrogeenan, the cross- AUiQS WO 98/08601 PCT/EP97/04751 7 linker is potassium ion. Similarly, when the polymer is algimate, the cross-linker is calcium ion. Again, when the polymer is polyvinyl alcohol, the cross-linker is borax ion.

In another embodiment of the invention, the polymer (ii) is selected from the group consisting of: carboxylic acid containing acrylic polymers; non-ionic polymers selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, modified corn starch and hydroxylalkyl cellulose or hydroxyalkylmethyl cellulose; and cationic polymers.

In a further embodiment of the invention, the aqueous composition containing the novel hydrogel particles is prepared first by adding injecting) a polymer solution containing the said two polymers and the water insoluble material into the said aqueous medium to form elongated (in theory, there is no limit to the size of the noodle since it can be continuously extruded), soft rigid enough to hold benefit agent, but soft enough to be broken down initially into smaller particles and later to deliver benefit agent to skin) polymer gel noodles which are then cut into the desirable gel particle size. More specifically, the aqueous composition is prepared as follows: dissolving the first and the second polymer in water to form a polymer solution and dispersing the water insoluble material into the prepared polymer solution to form a hydrogel precursor solution; WO 98/08601 PCT/EP97/04751 8 formulating the aqueous composition such that the first polymer is not soluble in said aqueous composition due to chemical or physical interaction and the second polymer is either soluble or dispersible; and injecting the hydrogel precursor solution into the aqueous composition to form elongated soft, hydrogel noodles and breaking the elongated soft noodles to hydrogel particles using low shear mixing device.

The second polymer or polymers forming the hydrogel composition is a property modifying polymer which is required to help stabilize benefit agent in the polymer hydrogel system and to help provide the proper gel strength of the overall hydrogel composition.

The invention also relates to the use of an aqueous composition as described above in personal cleansing and, in particular, skin care creams and products.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the effect of carrageenan (one of possible network forming polymers which insolubilize in the aqueous medium) concentration on gel strength of a hydrogel particle.

Figure 2 shows the effect on gel strength when Acrysol (one of possible property modifying polymers which are soluble both in water and in aqueous medium), an acrylic polymer, is combined with carrageenan.

DETAILED DESCRIPTION OF THE INVENTION In one embodiment, the present invention relates to WO 98/08601 PCT/EP97/04751 9 hydrogel compositions which are uniformly dispersed and stably suspended in aqueous compositions designed for personal cleansing or skin care applications. The hydrogel composition exists in the aqueous solution as a separate polymer gel phase formed when at least one polymer network forming polymer insolubilizes when placed in the aqueous solution; a second property modifying polymer or polymers which is soluble or dispersible in the aqueous solution, is also required) present as macroscopic domains having a particle size greater than 25 micrometers, preferably greater than 100 micrometers, up to about several centimeters). Furthermore, these domains are capable of trapping water insoluble agents, hereafter designated the "benefit agent"; within the gel structure, inside a web or network formed by the network forming polymer(s) and the property modifying polymer(s). The hydrogel composition must have sufficient gel strength (generally provided by the first network forming polymer(s)) to retain the integrity of the discrete domains, and to trap and hold the insoluble benefit agent(s) during processing and storage of the aqueous composition. However, the hydrogel must also be soft enough and capable of disintegrating smoothly when the composition is applied to and rubbed onto the intended substrate, such as skin, without causing any undesirable feeling of foreign matter or grittiness, due to the breaking or due to the components of the hydrogel particles. The softness of the gel particles can be manipulated by the amount of property modifying polymer(s) and network forming polymer(s) incorporated into the gel composition.

In a second embodiment of the invention, the hydrogel dispersions or structures are generally prepared by first emulsifying or dispersing the water insoluble benefit agent in an aqueous polymer solution containing both the network forming polymer and the property modifying polymer to form an C6360 emulsion or dispersion. This aqueous polymer solution which contains the dispersed benefit agent will henceforth be designated as the "hydrogel precursor solution". The hydrogel precursor solution containing the dispersed benefit agent (and also containing both the first and second polymers defined as and above) is then added or injected to and mixed with an appropriate aqueous solution under such conditions that the hydrogel dispersion precursor becomes insoluble (due to component apon contact with the aqueous solution to form spherical, noodle shaped or in some cases irregular shaped hydrogel domains uniformly dispersed in said aqueous solution.

Hydrogel dispersion can be accomplished either in a batch wise process or in a continuous process depending on how the hydrogel precursor solution and the aqueous composition are mixed. A batch process such as an overhead mixer or a flotation machine or a continuous process such as a two fluid coextrusion nozzle, an in-line injector, an inline mixer or an in-line screen can be used to make the hydrogel dispersion. The size of the hydrogel composition in the final composition can be manipulated by changing the mixing speed, mixing time, the mixing device and the viscosity of the aqueous solution. In general, by reducing the mixing speed, decreasing the mixing time, lowering the viscosity of the aqueous solution or using a mixing device that produces less shear force during mixing, one can produce hydrogel compositions of larger size. The size of the hydrogel domains particles), should have at least one dimension the diameter) that is larger than 25 Jm and preferably larger than 100 im to allow optimal transfer of the hydrogel to the substrate during the rubbing process.

The diameter may be as high as several centimeters.

Injection/low shear mixing processes are preferred for making the hydrogel particles. The hydrogel precursor solution is WO 98/08601 PCT/EP97/04751 11 injected to or co-extruded simultaneously with the aqueous solution to form elongated soft hydrogel noodles. In theory, the noodles have no upper size limit as they are extruded.

(As noted, after mixing, hydrogel particles should be at least 25 microns). The prehardened soft hydrogel noodles is then broken to irregular shape of hydrogel particles using low shear mixing devices such as low speed flotation machine or mechanical mixer in a batch process or in-line static mixer or in-line screen in a continuous process. The in-line mixing process is preferred due to better trapping or retention of water insoluble benefit agents inside the gel particles and better control on the size of the hydrogel particles. The prehardened elongated hydrogel noodle should be soft enough such that it can be broken easily at the low shear mixing condition. If the prehardened hydrogel noodle is too rigid then the hydrogel noodles tend to plug the in-line mixer or entangle with the mechanical mixer causing problems during the process. The rigidity of the prehardened hydrogel noodle can be manipulated easily by the composition of the hydrogel precursor solution or the composition of the aqueous solution and the hardening time of hydrogel noodles in the aqueous solution. In general the hydrogel noodle's rigidity can be reduced by reducing the amount of network forming polymer or increasing the level of property modifying polymer in the.hydrogel precursor solution; by reducing the hardening time of hydrogel noodle in the aqueous solution; and by reducing the concentration of cross-linking agent in the aqueous solution.

Hydroael and Aqueous Composition The hydrogel and aqueous composition comprising such comprise three essential components: i) a hydrogel forming polymer system (comprising a first polymer which WO 98/08601 PCT/EP97/04751 12 insolubilizes upon contact with a suitable aqueous solution for gel network formation; and a second property modifying polymers which stabilizes the benefit agent and/or modifies gel strength); ii) a water insoluble benefit agent (components and (ii) together form the "hydrogel" composition when formed in the aqueous solution composition and, iii) an aqueous solution composition capable of suspending the hydrogel and maintaining its integrity due to insolubility of first polymer. Each of these components is described in greater detail below.

As noted, the hydrogel structure or composition comprises a hydrogel forming polymer system (containing at least two polymers) and (ii) a water insoluble benefit agent.

Hvdrogel Forming Polymer System Polymer systems useful for forming hydrogels (component above) with desirable properties comprise in turn a first polymer which is soluble in water but insolubilizes when placed in an aqueous solution composition (component (iii) above); and a second property modifying polymer which ensures the final hydrogel composition is not so strong that it will not disintegrate smoothly when the hydrogel is applied to a substrate, skin. and but still has sufficient gel strength to retain the benefit agent during processing and storage.

Together polymers and form a web or network which retains the benefit agent. Each of polymers and and the mechanism whereby polymer is insolubilized in the surfactant composition are discussed in greater detail below.

C6360 13 First Polymer The first polymer is, in its broadest sense, defined as any water soluble polymer that is made insoluble when placed in the aqueous solution composition (iii). This insolubilization is accomplished using one of the following insolubilization mechanisms: Thermal celation Suitable polymers that exhibit this type of gelling behavior can be made insoluble by thermal gelation) are those that are soluble in water at a temperature higher than about 40-50'C and which form a gel after the polymer solution is cooled to room temperature.

Examples of such polymers include: i) gel forming polysaccharides such as carrageenans or agars.

Particularly preferred polymers of this type are the carrageenan polymers. Particularly suitable carrageenans are those manufactured by the FMC corporation and sold under the trade name Gelcarin GP911, and Gelcarin 379; ii) gel forming proteins. Particularly preferred gel forming proteins are gelatins. Suitable gelatins include Gelatin G 9382(trademark) and G 2625 (trademark)sold by Sigma Chemicals; and iii) thermally gelling synthetic polymers such as poly (N-isopropylacrylamide) homo or copolymers or polyacrylate or methacrylate containing polymers that incorporate as one of the monomer units an acrylic or methacrylic ester of a long chain and preferably linear alcohol. Examples of the latter class of polymers are those sold by Landec Labs Inc. under the trade name Inteliners.

Precipitation or coacervation: Suitable polymers which exhibit this type of behavior are those that are soluble in water at room temperature but can be made substantially insoluble by changing the physical or chemical WO 98/08601 PCT/EP97/04751 14 properties of the aqueous solution such as, for example, the pH or electrolyte concentration. One example of a particularly suitable pH sensitive polymer is Chitosan (polyglucosamine) or its various chemically modified variants. Particularly useful chitosans are those sold by Pronova Biopolymers under the trade name Seacure 343, and Seacure 443. These materials have a molecular weight ranging from 10,000 to 100,000. Chitosan is an especially useful network forming polymer for the hydrogel compositions of the present invention because it can be dissolved in an aqueous solution with a pH lower than 4.5 to form a uniform hydrogel precursor solution. Upon mixing this solution with an aqueous solution such as a liquid cleanser which has a typical pH in the range of 5.0 to 7.0, an insoluble polymer is readily formed.

Another class of polymers that form suitable hydrogel networks by precipitation/coacervation are electrolyte sensitive polymers. These polymer will precipitate to form insoluble networks by adding the polymer solution into a liquid cleanser containing high levels of salt or ionic surfactants. Examples of such polymers include: polyvinyl alcohol having a molecular weight greater than 13,000 Daltons and a degree of hydrolysis in the range of 78% to 100%; and hydroxyethylcellulose such as those sold by Aqualon Corp.

under the trade name Natrosol.

It should be understood that the same polymer may be in either class soluble, but insolubilized upon contact with aqueous surfactant solution); or class soluble in both water and aqueous surfactant solutions) depending on what else is in the aqueous solution.

Thus, a polymer sensitive to electrolyte concentration might be a class polymer in a composition without electrolyte, but become a class polymer in an aqueous WO 98/08601 PCTEP97/04751 surfactant solution containing sufficient electrolyte to insolubilize the polymer. The same is true if certain polymers become insoluble in the presence of certain crosslinkers. If the cross-linker is not present in the base formulation, the polymer may be a polymer, but, if present, the polymer becomes a polymer.

Cross-linking: Suitable water soluble polymers exhibiting this type of behavior are those that can form water insoluble complexes with a water soluble monomeric or polymeric cross-linker salts or polyacrylates). The insoluble polymer network can be formed by reacting the polymer aqueous solution with the cross-linker before or after adding the polymer aqueous solution into the aqueous solution composition. Examples of readily cross-linkable polymers include: 6-Carrageenans which can be cross-linked with potassium ions, alginates which can be cross-linked with a calcium ions or polyvinyl alcohols which can be crosslinked with borax ion.

Second or Property Modifying Polymers The polymers described above are essential to form the hydrogel as they provide the backbone network without which the hydrogel composition can not -exist. However, these polymers alone are usually too rigid to provide a smooth rubin properties and are not sufficiently surface active in the hydrogel precursor solution to effectively stabilize emulsions of or dispersions of water insoluble benefit agents of the type used in the present invention. A second more surface active water soluble polymer was found necessary in forming such dispersions having the required stability.

A second function of the property modifying polymer concerns its effect on gel strength. As stated above, it is WO 98/08601 PCT/EP97/04751 16 desirable that the hydrogel composition is sufficiently strong such that the dispersed hydrogel domains/particles remain discrete in order to effectively trap the benefit agent within their structure, yet that they be sufficiently soft (non-rigid) that the hydrogel domains/particles rub smoothly into the skin during product use. This balance can be achieved by optimizing the polymer composition of the hydrogel.

It has been found that certain water soluble polymers when incorporated into the hydrogel precursor solution along with the first polymer can effectively modify the gel strength of the hydrogel composition to achieve this balance.

The hydrogel strength and the in-use skin feel properties can thus be manipulated easily by controlling the amounts of the network forming polymer (first polymer) and the second property modifying polymer in the hydrogel precursor solution.

A variety of hydrophilic anionic, cationic, amphoteric, and nonionic water soluble polymers can be utilized for these purposes. These second polymers can be soluble in the aqueous solution composition (in contrast to the first polymers which are not) and have a molecular weight greater than 5,000 Daltons, preferably higher than 10,000 Daltons, and most preferably higher than 50,000 Daltons.

Examples of water soluble polymers that have been found useful as property modifying polymers include: i) carboxylic acid containing acrylic polymers such as alkali soluble polyacrylic latexes sold under the trade name of Acrysol or Aculyn by Rohm Haas and cross-linked polyacrylic acids and copolymers sold by B. F. Goodrich under the trade name Carbopol; ii) nonionic polymers such as polyvinyl alcohol from Air Products sold under the trade name Airvol, polyvinyl WO 98/08601 PCT/EP97/04751 17 pyrrolidone from ISP Technologies Inc., modified corn starch such as those sold under the trade name of Capsule or Purity Gum Bee by National Starch Chemicals, hydroxyethylcellulose sold by Aqualon under the trade name of Natrosol; hydroxylpropyl methylcellulose from Dow Chemical named Methocel and iii) cationic polymers such as modified polysaccharides including cationic guars available from Rhone Poulenc under the trade names Jaguar C13S, and Jaguar C14S, cationic modified cellulose such as Ucare Polymer JR 30 or JR 40 from Amerchol, synthetic cationic polymers such as polydimethyldialkyammonium chloride homo- or copolymers sold under the trade name Merquat 100, Merquat 550 sold by Calgon, and vinyl pyrrolidone/dimethylamino ethyl methacrylate copolymer sold under the trade name of Gafquat 755 from GAF Chemical.

The second component of the "hydrogel" composition is the benefit agent (component (ii) above). This is described in greater detail below.

(ii) Benefit Agent Benefit agents in the context of the instant invention are materials that have the potential to provide a positive and often longer term effect to the substrate being cleaned, to the skin, hair or teeth. In the case of skin, benefit agents suitable for this invention are water insoluble materials that can protect, moisturize or condition the skin after being deposited from the aqueous composition such as a liquid cleansing composition.

Preferred benefit agents include: a) silicone oils, gums and modifications thereof such as linear and cyclic polydimethylsiloxanes; amino, alkyl WO 98/08601 PCT/EP97/04751 18 alkylaryl and aryl silicone oils; b) fats and oils including natural fats and oils such as jojoba, soybean, sunflower, rice bran, avocado, almond, olive, sesame, persic, castor, coconut, mink oils; cacao fat, beef tallow, lard; hardened oils obtained by hydrogenating the aforementioned oils; and synthetic mono, di and triglycerides such as myristic acid glyceride and 2ethylhexanoic acid glyceride; c) waxes such as carnauba, spermaceti, beeswax, lanolin and derivatives thereof; d) hydrophobic plant extracts; e) hydrocarbons such as liquid paraffins, petrolatum, microcrystalline wax, ceresin, squalene, squalane, pristan and mineral oil; f) higher fatty acids such as lauric, myristic, palmitic, stearic, behenic, oleic, linoleic linolenic, lanolic, isostearic and poly unsaturated fatty acids (PUFA) acids; g) higher alcohols such as lauryl, cetyl, styrol, oleyl, behenyl, cholesterol and 2-hexadecanol" alcohol; h) esters such as cetyl octanoate, myristyl lactate, cetyl lactate, isopropyl myristate, myristyl myristate, isopropyl palmitate, isopropyl adipate, butyl stearate, decyl oleate, cholesterol isostearate, glycerol monostearate, glycerol distearate, glycerol tristearate, alkyl lactate, alkyl citrate and alkyl tartrate; sucrose ester sorbitol ester and the like; i) essential oils such as fish oils, mentha, jasmine, camphor, white cedar, bitter orange peel, ryu, turpentine, cinnamon, bergamot, citrus unshiu, calamus, pine, lavender, bay, clove, hiba, eucalyptus, lemon, starflower, thyme, peppermint, rose, sage, menthol, cineole, eugenol, citral, Citronelle, borneol, linalool, geraniol, evening primrose, camphor, thymol, spirantol, pinene, limonene and terpenoid oils; WO98/08601 PCT/EP97/04751 19 j) lipids and lipid like substance such as cholesterol, cholesterol ester ceramides, sucrose esters and pseudoceramides as described in European Patent Specification No. 556 957; k) vitamins such as vitamin A and E, and vitamin alkyl esters, including vitamin C alkyl esters; 1) sunscreens such as octyl methoxyl cinnamate (Parsol MCX) and butyl methoxy benzoylmethane (Parsol 1789); m) Phospholipids such as lecithins; n) antimicrobial such as 2-hydroxy-4,2',4'trichlorodiphenylether (DP300) and 3,4,4'trichlorocarbanilide (TCC); and mixtures of any of the foregoing components.

Another benefit agent contemplated are water soluble materials glycerin, enzyme, -hydroxy acid) entrapped in any of the oils mentioned above.

The benefit agent is incorporated into the aqueous hydrogel precursor solution (the solution that contains the first polymer and the second property modifying polymers).

This can be accomplished simply by mixing the benefit agent with the aqueous hydrogel precursor solution or by preemulsifying the benefit agent in an aqueous solution which is then mixed with the hydrogel precursor solution. In the direct mixing process low level of surfactants can be added into the hydrogel precursor solution to enhance emulsification and stability of the skin benefit agent. The benefit agent is present in the aqueous polymer solution in the amount of 5 to 65 by preferably 10 to 40 by wt.% of the hydrogel composition. Depending on the mixing conditions, polymer composition composition of polymers forming hydrogel) and concentration, the size of the benefit agent particle can vary from 0.2 micrometer up to several hundred micrometers. For better stability and WO 98/08601 PCT/EP97/04751 efficient deposition, the particle size of benefit agent is preferably in the range of 5 to 150 micrometers.

As indicated above, the invention comprises an aqueous solution composition comprising the hydrogel composition more fully defined above. The liquid composition itself is described in greater detail below.

(iii) Aqueous Solution Compos ition As noted, the invention relLtes to the aqueous solution composition in which the hydrogel incorporating the benefit agent containing the agent in a web produced by polymers and is dinpersed. Depending on the application, the aqueous solution composition can comprises from about 0% to about 60 wt%, preferably 2% to 40 wt% of surfactants selected from any known surfactants suitable for personal care or cleansing applications. In general, for personal cleansing application higher level of surfactants typically in the range of 5 to 50 wt% are used. The surfactants are selected from the group consisting of anionic, nonionic, cationic, amphoteric and zwitterionic surfactants and mixtures thereof. It should be noted that surfactants are not a necessary component of the composition and, for example, non-surfactant skin lotion compositions are contemplated.

The aqueous solution composition should be formulated in such a way that the first water soluble polymer becomes insoluble upon contact with the aqueous solution composition.

It is also critical that the aqueous solution composition is capable of suspending the dispersed hydrogel phase for hydrogel processing and stable hydrogel suspension. This requires that the liquid compositions have a sufficiently high low-shear viscosity to prevent settling (or creaming) of C6360 21 the hydrogel compositions under the action of gravity during processing and storage. This can be achieved by utilizing aqueous solution compositions formulated to have a viscosity of at least 300 cps, and preferably 1,000 cps, more -2.

preferably 3,000 at a shear rate of 10 sec at 25°C. This viscosity is generally sufficient to stably suspend the large hydrogel dispersions of the instant invention without appreciable gravitational phase separation. As the particle size of hydrogel dispersion increases, liquids that have a higher viscosity are required to achieve adequate stability.

Viscosity of an aqueous solution composition can be increased either by the inclusion of polymeric, organic or inorganic thickeners in the composition or by the careful selection and combination of surfactants. Both methods are well known in the art. For example, U.S. Patents 4,917,823, 4,491,539, 4,556,510, 4,678,606 and 5,002,680 teach the use of polymeric thickeners to increase the viscosity of a liquid cleanser, while U.S. Patents 5,236,619, 5,132,037, 5,284,603, 5,296,158 and 5,158,699 disclose ways to formulate a stable viscous liquid composition using an appropriate combination of surfactants.

The surface active agent, when used, can be selected from any known surfactant suitable for topical application to the human body.

One preferred anionic detergent is fatty acyl isethionate of formula

RCO

2

CH

2

CH

2

SO

3

M

where R is an alkyl or alkenyl group of 7 to 21 carbon atoms and M is a solubilizing cation such as sodium, potassium, ammonium or substituted ammonium. Preferably at least three quarters of the RCO groups have 12 to 18 carbon atoms and may be derived from coconut, palm or coconut/palm WO 98/08601 PCT/EP97/04751 22 blends.

Another preferred anionic detergent is alkyl ether sulphate of formula: RO(CH2CHO), SOM where R is an alkyl group of 8 to 22 carbon atoms, n ranges from 0.5 to 10 especially 1.5 co 8, and M is a solubilizing cation as before.

It should be understood that the anionic surfactant is also intended to encompass fatty acid soaps.

Fatty acid soaps are typically alkali metal or alkanol ammonium salts of aliphatic alkane or alkene monocarboxylic acids. Sodium, potassium, mono-, di and tri-ethanol ammonium cations, or combinations thereof, are suitable for purposes of the invention. The soaps are well known alkali metal salts of natural or synthetic aliphatic (alkanoic or alkenoic) acids having about 8 to 22 carbons, preferably 12 to about 18 carbons. They may be described as alkali metal carboxylates of acrylic hydrocarbons having about 12 to 22 carbons.

Examples of soap which may be used may be found in U.S.

Patent No. 4,695,395 to Caswell et al. and U.S. Patent No.

4,260,507 (Barrett), both of which are incorporated herein by reference.

Other possible anionic detergents include alkyl glyceryl ether sulphate, sulphosuccinates, taurates, sarcosinates, sulphoacetates, alkyl phosphate, alkyl phosphate esters and acyl lactates, alkyl glutamates and mixtures thereof.

Sulphosuccinates may be monoalkyl sulphosuccinates having the formula: C6360 23 RS0CCHCH (SO 3 M) COM; and amido-MEA sulphosuccinates of the formula: RKCONHCHCHO CCH CH (SO 3 M) CO 2

M;

wherein R 5 ranges from C,-C20 alkyl, preferably alkyl and M.is a solubilizing cation.

Sarcosinates are generally indicated by the formula:

RSCON(CH

3

CHCO,M,

wherein R 5 ranges from C,-C20 alkyl, preferably C,-C6 alkyl.

Taurates are generally identified by the formula: R CONR'CH 2 CHSO3M, wherein R 5 ranges from C,-C20 alkyl, preferably alkyl, R 6 ranges from C:-C alkyl, and M is a solubilizing cation.

Another useful surfactant is alkylethoxy carboxylate indicated by the following formula:

(OCHCH

2

COOM,

wherein R S ranges from C,-C20 alkyl, preferably C:.-C26 and M is a solubilized cation.

Harsh surfactants such as primary alkane sulphonate or alkyl benzene sulphonate will generally be avoided.

Suitable nonionic surface active agents include alkyl polysaccharides, aldobionamides lactobionamides such as taught in U.S. Serial No. 981,737 to Au et al., hereby incorporated by reference into the subject application), ethyleneglycol esters, glycerol monoethers, polyhydroxyamides (glucamide) including fatty acid amides such as taught in U.S.

Patent No. 5,312,934 to Letton, (hereby incorporated by reference into the subject application), primary and secondary alcohol ethoxylates, especially the C,_20 .aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol.

AMENDED S'HEET WO 98/08601 PCT/EP97/04751 24 The surface active agent is preferably present at a level of from 1 to 35 preferably 3 to 30 wt.%.

It is also preferable that the composition includes from 0.5 to 15 wt.% of a cosurfactant with skin mildness benefits.

Suitable materials are zwitterionic detergents which have an alkyl or alkenyl group of 7 to 18 carbon atoms and comply with an overall structural formula.

0 R 2 11 I

R

1

R

3 where R' is alkyl or alkenyl of 7 to 18 carbon atoms,

R

2 and R 3 are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 3 carbon atoms, m is 2 to 4, n is 0 or 1, X is alkylene of 1 to 3 carbon atoms optionally substituted with hydroxyl, and Y is or -SO 3 Zwitterionic detergents within the above general formula include simple betaines of formula:

R

2

R

1 N' CH 2

CO-

R

3 and amido betaines of formula: 111 WO 98/08601

R

2

R

1 -[-CONH (CH2) m -N'-CH2CO, PCT/EP97/04751 where m is 2 or 3.

In both formulae R 1

R

2 and R 3 are as defined previously.

R may, in particular, be a mixture of C,1 and alkyl groups derived from coconut so that at least half, preferably at least three quarters of the groups R 1 have 10 to 14 carbon atoms. R 2 and R 3 are preferably methyl.

A further possibility is a sulphobetaine of formula: R1

(CH

2 3SO; R' -[-CONH where m is 2 or 3, or variants of these in which

(CH,)

3 SO is replaced by

OH

-CHCHCHSO

3 C6360 26 R R 2 and R 3 in these formulae are as defined previously.

Compositions of the invention may be formulated as products for washing the skin or hair, bath or shower gels, hand washing compositions, facial washing liquids, shampoos; pre and post shaving products; rinse off, wipe off and leave on skin care products.

The compositions of the invention will generally be pourable liquids or semi liquids pastes and will preferably have a viscosity in the range 1500 to 100,000 mPas measured at a shear rate of 10s' at 25 0 C in a Haake Rotoviscometer Other typical components of the compositions include opacifiers, preferably 0.2 to 2.0 preservatives, preferably 0.2 to 2.0 wt.% and perfumes, preferably 0.5 to wt.%.

In a second embodiment of the invention, the invention relates to a process for preparing an aqueous composition comprising hydrogel particles wherein said hydrogel particles have the following composition: 0.1 to 30% by wt. hydrogel composition of at least one polymer soluble in water which polymer is insolubilized when placed in an aqueous solution; (ii) 0.2 to 30% by wt. hydrogel composition of a polymer soluble in water, and soluble or dispersible in aqueous solution; and (iii) 1.0% to 60% water insoluble benefit agent entrapped in a network formed by and (ii); wherein-the particles of benefit agent(iii) have a particle size of 0.2 to 200 micrometers; wherein said hydrogel is greater than 25 micrometers; and wherein the size of the hydrogel is greater than that of the benefit agent; ~nr~ SET I_ C6360 27 wherein said process comprises the steps of: dissolving polymer and (ii) to form a polymer solution in water dispersing component (iii) into the polymer solution to form a hydrogel precursor solution; formulating an aqueous solution such that the first polymer is not soluble and second polymer (ii) is soluble or dispersible in the aqueous solution; combining said hydrogel precursor solution and the aqueous solution to form elongated, soft hydrogel noodles when hydrogel precursor contacts the aqueous solution, the noodles being sufficiently rigid to entrap benefit agent yet sufficiently soft to readily rupture when applied to a substrate; and breaking the noodles to hydrogel particles using mechanical mixer or in-line mixer.

In order to better understand the invention the following non-limiting examples are provided. As noted, the examples are not intended to limit the claims in any way.

All percentages mentioned are intended to be percentages by weight unless indicated otherwise.

EXAMPLES

Example i. Preparation of hydrogel dispersions hydrogel composition) containing silicone oil by a direct mixing process.

There are a number of ways that a polymeric hydrogel can be dispersed into an aqueous based surfactant composition in such a way that the hydrogel forms discrete domains. All of the technique we have found useful take advantage of rapid gelation or cross-linking that occur for certain types of water soluble polymers when their solution environment changes, a change in pH, ionic strength, temperature, type of ion, presence of cross-linker, etc.

C6360 28 This example illustrates how hydrogel dispersion useful in the present invention can be prepared by directly mixing an appropriate hydrogel forming polymer solution (called the hydrogel precursor solution) with a liquid cleanser using conventional mechanical stirrer. In this case, the polymer system is chosen such that the change in pH that arises when the hydrogel precursor solution is mixed with the cleansing composition induces a phase changes (gelation). Gelation is sufficiently rapid that the added precursor hydrogel solution (containing first polymer which insolubilizes when added to aqueous surfactant solution; second property modifying polymer and benefit agent), which itself is water continuous, does not first dissolve in the cleansing composition but rather forms a discrete dispersed aqueous phase.

Preparation of hvdroqel precursor solution A 40% emulsion of silicone oil (60,000 centistokes, ex Dow Corning) was formed by mixing 40 parts of the silicone oil to parts of aqueous polymer solution which contained 1 wt% of Chitosan (first polymer) (Sea Cure 340(trademark) ex. Protan), 0.8 wt% of acetic acid and 3 wt% of hydroxyl ethylcellulose (second polymer) (Natrosol 250 MR (trademark)ex. Aqualon) at 400 rpm for 30 minutes using an overhead stirrer. The emulsion so prepared contained droplets of silicone oil having a broad size distribution ranging from about 4 jtm to 50 gm dispersed in the polymer solution.

Preparation of hydrogel dispersion by direct mixing 12.5 parts of the hydrogel precursor solution containing emulsified silicone oil described above was added to 87.5 parts of a liquid cleanser whose composition is described in Table 1.

Mixing was accomplished with an overhead stirrer (Model ex Tekmar). Two dispersions were prepared that had identical

I

C6360 29 chemical composition but differed in the stirring speed used to form the dispersions. In Example 1A, the dispersion was mixed at 80 RPM for 25 minutes while for Example 1B the mixing speed was 200 RPM. Both examples contained irregular shaped hydrogel domains.that themselves contained emulsified silicone oil droplets entrapped within the gel matrix.

The compositions of Examples 1A and 1B are detailed in Table 2 along with some of their physical properties.

Table 1. Liquid Cleanser Composition Ingredient Wt% Cocamidopropyl Betaine 5.6% Sodium Cocoyl Isethionate Sodium Laureth Sulfate 1.4% Glydant XL (trademark) 0.14% Ammonium Sulfate 0.09% Jaguar C13S (trademark) 0.9% Perfume 0.42% Deionized Water 87.95% «r/Y Afimrk^-n-j wO Y2/usoul PCT/EP97/04751 Table 2. Composition and properties of hvdroael disnt-rsinn form~c1 hv 1ir~c~r mi~inci Example 1A Example 1B Example 2 Ingredient Wt% Wt% Wt% Silicone Oil 40% 40% Chitosan 0.6% 0.6% 0.6% Hydroxyethylcellulose 1.8% 1.8% Jaguar C13S 1.8% water to 100 to 100 to 100 Silicone Oil drop 4-50:m 4-50:m 1-25:m size Hydrogel domain size 255 nm 227 nm 157 nm Example 2. Further illustration of hydrogel dispersion containing silicone oil prepared by direct mixing A hydrogel precursor solution similar to the one described in Example 1 but having a different polymer composition was prepared as follows. 40 parts of 60,000 centipoise silicone oil was emulsified in 60 parts of aqueous polymer gel solution which contained 1 wt% of Chitosan (first polymer) (Sea Cure 340 ex. Protan), 0.8 wt% of acetic acid and 3 wt% of a cationic guar polymer (second polymer) (Jaguar C13S ex. Rhone-Poulenc) at 400 rpm for 30 minutes using an overhead stirrer.

12.5 parts of this hydrogel precursor solution containing emulsified silicone was then added to 87.5 parts of the liquid cleanser described in Table 1 and mixed at 80 rpm for minutes. This process lead to a dispersion that contained irregular shaped particles of hydrogel in which silicone oil droplets were entrapped in the gel matrix. The composition and properties of this dispersion are also summarized in Table 2.

C6360 31 Example 3. Hydrogel dispersions containing silicone oil prepared by extrusion This example demonstrates that hydrogel dispersions useful for the purposes of the present invention can also be prepared by a coextrusion process. Specifically the example illustrates compositions that are prepared by co-extruding a hydrogel precursor solution (containing in this case dispersed silicone oil) with an aqueous liquid cleaner composition by means of a two fluid nozzle. This process produces hydrogel compositions dispersed in the form of noodle shape particles suspended in the liquid cleanser composition. The noodle shape hydrogel dispersion gives a unique appearance to the liquid cleanser. Alternatively, the dispersion can be processed further by any number of shear techniques to chop or subdivide the noodles into a desired size range. The process is illustrated for a silicone oil containing hydrogel composition, but can be used in conjunction with a great variety of materials as will be shown in subsequent examples.

Preparation of hydrogel precursor solution dispersed silicone oil Silicone oil was mixed with an aqueous solution of a neutralized carboxyl acid containing acrylic copolymer (second polymer) (Aculyn-33(trademark), Rohm Haas) in an aqueous solution with a pH in the range of 7 to 7.5 by mechanical stirring. In this case the Aculyn-33 was used as the property modifying polymer. The oil droplet size, which varied from 5 to 150 jpm in diameter, was controlled by the concentration of Aculyn-33 and the stirring speed. Higher concentration and faster stirring led to smaller oil droplets. An aqueous 6carrageenan (Gelcarin GP-911(trademark), FMC) solution, the first polymer (network forming polymer), was added into the mixture with gentle stirring 100 rpm) at 45-50 For this example two l hi^'l C6360 32 hydrogel precursor dispersions were prepared that differed in the size of the silicone oil droplets. In one dispersion, the silicone oil droplet size was in the range of 2-30 tm while in the second dispersion the droplet size fell within 40 -100 tm.

Preparation of hydrogel dispersion by coextrusion The warm (45-50°C) precursor solution described above was fed into the central orifice of a commercially available nozzle (Series No. 1/4 XA SR450 A ex Bete Fog Nozzle Inc.) by means of a high pressure syringe pump (Syringe pump model ex Harvard Apparatus). Simultaneously, a cool (room temperature 22 shower gel formulation (composition shown in Table 3) was injected to the outer orifice of the nozzle to form the final product which contained "noodle-shaped" hydrogel composition particles. A high pressure syringe pump was also used to transfer the cleansing composition, in this case a shower gel. The hydrogel and silicone contents in the final dispersion were controlled by controlling the ratio of the flow rates of the hydrogel precursor and the surfactant compositions. This ratio was adjusted to ensure that the final product contained 5 wt.% silicone oil.

The characteristics of the two hydrogel dispersions, Example 3A and Example 3B are summarized in Table 4. They consisted of noodle shaped particles of approximately 1000 |tm in diameter suspended in the shower gel composition of Table 3 C636 0 33 Table 3. Surfactant cleansing composition used to prepare hydrocel dispersions of Example 3 Ingredient wt.% Sodium Lauryl Ether(3) Sulfate 4 Cocoamido Propyl Betaine 1 Dodecyl polyglycoside Perfume (SG 146, Quest) 1 Sorbic Acid 0.37 Sodium Citrate. 2H20 0.49 Sodium Hydroxide 1 Carbopol ETD2020 0.9 Antil 1413 (trademark) 0.97 to 100 Footnote 1: Adjust pH to 5.24 0.1 with NaOH Footnote 2: Cross-linked polyacrylic acid Footnote 3: Polyethylene glycol propylene glycol oleate Table 4. Characteristics of "Noodle Shaped" Hydrocel Particles formed by coextrusion (Example 3) Example Hydrogel Oil Phase Diameter Silicone Oil Noodle's (60,000 cs) Crosssection (pm) Polymer Water wt.% Droplet Size (tm) Type wt.% wt.% 3A Carrageenan 1.2/0.4 38.4 60.0 40-100 1 /Aculyn 3B Carrageenan 1.2/0.4 38.4 60.0 2-30 1 /Aculyn _RA* o C6360 34 Aculyn is neutralized carboxyl acid containing acrylic copolymer.

Example 4. Effect of Polymer Composition on hydrogel properties.

This method illustrates how the rheological properties of the hydrogel which affect their in-use properties can be manipulated by the selection and concentrations of networkforming (first) and property modifying (second) polymers.

A series of model hydrogel particles were prepared by a cross-linking method using carrageenan as the network polymer and potassium ions as the cross-linking agent. The dispersions were made by a variant of the extrusion process described in Example 3 using an aqueous solution of KC1 as the model cleansing composition. The hydrogel dispersions differed only in the concentration of carrageenan (first polymer) used in the hydrogel precursor solution which ranged from 1 to 6 wt%. Approximately spherical particles were formed all having a diameter of about 3000 pLm.

An Instron (Model 1122) was found to be a suitable instrument to differentiate the strength of various gel compositions described above. The measurement procedure was as follows. A hydrogel particle was carefully removed from the dispersion with a spatula and excess liquid was removed by placing them on a kimwipe. The approximate diameter of the hydrogels was measured with calipers. The hydrogel was then transferred to a metal platform base of the Instron and a Newton load was lowered until it came in contact with the hydrogel particle. The Instron was then turned on and the force was measured as a function of distance using a chart recorder. The chart recorder was set at a crosshead speed of 1 WO 98/08601 PCT/EP97/04751 mm/min and a chart speed of 50 mm/min which allowed for a 2 Newton full scale load reading. The force was recorded at 0.50 mm, 1.00 mm, and 1.50 mm. The elastic modules of the sample was calculated by dividing the force by the section area of the hydrogel and the strain. It should be noted that the particles remained hydrated during the course of the measurement.

The gel strength measure by the above procedure for the series of model hydrogel particles are shown in Figure 1.

These results indicated that the gel strength increased significantly with increasing carrageenan concentration. When the polymer concentration was higher than 2 wt%, the gel felt quite hard to the touch, and did not rub smoothly into the skin. Although such particles might trap benefit agents and remain stable during storage, they would not be optimum for cleansing applications because the delivery of the benefit agent would not be uniform, and the composition would feel gritty. These results also indicate that if it was desired to decrease the gel strength of the hydrogel particles this could only be achieved by decreasing the concentration of polymer within the gel. This would greatly limits the flexibility of the technology. As will be shown below, this limitation can be overcome by using a second polymer to modify the properties of the hydrogel, its gel strength.

Another set of model hydrogel particles were prepared by the same procedures used above. Each hydrogel precursor solution contained 2 wt% carrageenan and from 0 to 2 wt% of an acrylic copolymer, Acrysol ASE-60 (Rohm Haas). This is the second property modifying polymer. The shape and size of the hydrated particles were all very similar and also similar to the all carrageenan hydrogels described previously. The influence of added Acrysol ASE-60 on the gel strength of hydrogel particles formed by cross-linking with K" is shown in Figure 2. The results indicate that the gel strength

I

C6360 36 decreased significantly with increasing Acrysol concentration even though the total concentration of polymer increased.

Hydrogels containing carrageenan and Acrysol in a weight ratio ranging from 3:1 to 2:1 (arrows in Figure 2) were capableof effectively trapping benefit agents such as emulsified emollient oil silicone oil, and yet rubbed smoothly into the skin without noticeable grit.

The above example is set forth for illustrative purposes to show how the gel strength can be tuned by selection of a polymer system comprising an network-forming and property modifying polymer. Care must be taken not to attach too much significance to the exact values of gel strength quoted above.

We have found that the quantitative effect of the polymer composition in the hydrogel precursor solution on the strength of a hydrogel particle depends significantly on the nature, particle size, and concentration of a benefit agent that may be dispersed in the precursor solution. Although the trends are the same, the exact values may change. Although complex, one skilled in the art can utilize a combination of polymers broadly falling in the definition of network-forming and property modifying agents to achieve the proper balance of gel strength for each situation.

Example 5. Deposition of silicone oil on skin ex-vivo.

The potential of various cleansing compositions to deposit silicone oil onto the skin during the washing process was determined using an ex-vivo model based on pig skin. The procedure is described below.

A 0.5 ml aliquot of tne test composition was applied to 5.08cm by 5.08cm by square strips of excised pig skin that had first been prewetted with tap water at 37 The composition was lathered for 10 seconds and then rinsed for 10 seconds under

I;A

WO 98/08601 PCT/EP97/04751 37 warm running tap water. The skin was then wiped once with a paper towel to remove excess water and allowed to dry for two minutes. A strip of adhesive tape was then pressed onto the skin for 30 seconds under a load of 10 g/cm 2 The adhesive tape employed was J-Lar Superclear (TM) tape having a width of 3 cm. In this test procedure, the silicone, which had deposited on the skin, will subsequently be transferred to the tape along with some of the outer skin layers.

The amounts of silicone and skin adhering to the tape were determined by means of X-ray fluorescence spectroscopy. The tape strips were placed in an X-ray fluorescence spectrometer with the adhesive side facing the beam of this machine. A mask is applied over the tape to define a standardized area in the middle of the tape which was exposed to the X-ray beam. The sample chamber of the machine was placed under vacuum before making measurements and the spectrometer was then used to measure the quantities of silicone and sulphur. The sulphur was representative of the amount of skin which had transferred to the tape.

The amount of silicone and sulphur observed with a clean piece of adhesive tape were subtracted from the experimental measurements. The experimental measurements for successive pieces of tape were added together and the cumulative totals of silicone and sulphur were expressed as a ratio of silicone to sulphur per unit area of skin. A higher Si/S ratio corresponds to a higher deposition level. A total of 10 tape strips were employed for each measurements.

The amount of silicone deposited on excised pig skin determined as described above for the compositions described in Examples 2-3 are listed in Table 5. It is clear from these results that the hydrogel compositions provided significant deposition of silicone oil to the skin in these tests.

C6360 38 Table 5. Deposition of Silicone from Shower Gel Example No. Silicone Deposition (Silicon/Sulphur Ratio) Example 2 1.38 Example 3A 28.0 Example 3B 7.1 Control 1 (Note 1) 0.3 Note 1. The control in this example is the shower gel composition shown in Table 3 which did not contain any silicone.

Example 6. Hydrogel dispersions made with different polymers.

This example illustrates that hydrogel dispersions can be prepared with a variety of polymers provided they possess the required hydrogel forming capabilities and gel strengths. In the composition described below, a cationic polymer Chitosan (first polymer) (Seacure 343 ex. Pronova Biopolymer) was used as the network forming polymer and a cationic modified guar (Jaguar C-13S, Calgon) and a synthetic cationic polymer polydimethyldialkylammonium chloride (Merquat 100,(trademark) Calgon) were used as the second or property modifying polymers. The hydrogel precursor solution was prepared by mixing 35 parts of 60,000 cps silicone oil with 65 parts of polymer solution containing 1.5 wt% Jaguar C13S, 0.75 wt% Chitosan, 0.10 wt% Merquat 100, 0.35% acetic acid and 0.05 wt% cocoamido propylbetaine at 300 rpm for 15 minutes using an overhead -stirrer. The resulting emulsion contained silicone oil droplets with size ranging from 2 ptm to 60 pm dispersed in the polymer solution.

y C6360 39 The extrusion process described in Example 3 was used to prepare 14.3 wt% dispersions (5 wt% silicone oil based on the total composition) of the hydrogels The surfactant system was the same as the one used in Example 3 (Table 3) except 0.3 instead of 0.97 of Antil 141 was used in the formula.

The hydrogel dispersion comprised noodle shaped particles dispersions that contained dispersed silicone oil having an average droplet size in the range of 2-60 |Jm.

The deposition of silicone oil from the composition of Example 6 (this example) shown in Table 6 The deposition tests were carried out according to the method described in Example 5 The dispersion exhibited a similar depositions to other hydrogels having similar silicone droplet size suggesting that the nature and characteristics of the dispersions may be more important in determining the level of deposition than is the exact polymer that is employed.

WO 98/08601 PCT/EP97/04751 Table 6. Deposition of silicone oil onto Dic skin from cleansin compositions containing disDersed hydroaels Sample No. Si:S Example 6 6.78 Control (same control as in Table 5) 0.3 Example 7. Illustration of the enhanced deposition produced by hydrogels.

One of the benefits of using the hydrogel dispersions of this invention is the enhanced deposition provided to agents that are incorporated within their structure relative to the agents used by itself. This example illustrates the effect for silicone oil. In particular, deposition of silicone oil from various skin cleansing compositions were compared in the deposition test described in Example 5. A set of compositions was prepared by directly emulsifying 60,000 cps silicone into the cleansing composition of Table 3 to make the droplet size of silicone oil about the same as those contained in the hydrogel dispersions of Examples 3A, 3B and 6.

The deposition results of hydrogel dispersions vs.

silicone emulsion alone are summarized in Table 7 and demonstrate that substantial enhancements in deposition can be achieved by incorporating the agent within a dispersed hydrogel domain.

1__1 C6360 41 Table 7. Enhancement of deposition of silicone oil from hydrocel"' Sample No. Silicone Oil Deposition Level (b) Droplet Size Si/S Ratio Si/S Ratio Silicone Silicone in Emulsions Hydrogel Alone (c) Example 3B 2-30 pm 7.1 1.2 Example 3A 40-100 jm 28.0 8.3 Example 6 2-60 jm 6.78 Note All compositions employed the surfactant base listed in Table 3. The concentration of silicone oil in the final composition was 5 wt% in all cases.

Note Deposition was measured by the ex-vivo method described in Example Note The same silicone oil were used in the preparation of the skin cleansing compositions by directly emulsifying the silicone oil into the skin cleanser.

Example 8. Preparation of hydrogel dispersion containing hydrocarbon oils A wide variety of ingredients can be incorporated into the hydrogel dispersion of this instant invention. Previous examples have illustrated several general features of these dispersions using silicone oils. Another class of useful materials are hydrocarbon oils. Some of the benefit agents of this class of materials are moisturizing agents such as petrolatum, emollients such as isopropyl palmitate and sunscreens such as Parsol MCX (trademark, 2-Ethylhexyl-P- Methoxy Cinnamate). These examples illustrates the use of hydrogels to WO 98/08601 PCT/EP97/04751 42 deliver such hydrocarbon oils.

Preparation of hydrogel precursor solution emulsions of different hydrocarbon oils i.e. 100% petrolatum, a mixture of 50 isopropyl palmitate and 50 petrolatum, and a mixture of 50 Parsol MCX and 50 of petrolatum were prepared by mixing 40 parts of the hydrocarbon oil to 60 parts of aqueous polymer solution which contained wt% Chitosan (first polymer) (Seacure 343 ex Pronova Biopolymer), 1.9 wt% Jaguar C13S (second polymer), 0.4 wt.% cocoamido propylbetaine and 0.25 wt.% acetic acid at 300 rpm for 20 minutes using an overhead stirrer. The mixing was done at room temperature except 100 petrolatum sample. The 100% petrolatum emulsion was prepared by melting the petrolatum at 60'C which was then added to the room temperature polymer solution and mixed at room temperature.

Preparation of hydrogel dispersion by coextrusion The extrusion process described in Example 3 was used to prepared 12.5 wt% dispersion of the hydrogels containing 100% petrolatum, 50%Isopropyl palmitate/50 petrolatum, and Parsol MCX/50% petrolatum respectively for examples 8A, 8B and 8C. The surfactant system was the same as the one used in Example 3 (Table 3) except no Antil 141 was used in the formula. All these samples comprised noodle shaped hydrogel dispersions with diameter about 1000 nm.

Examples 9. Preparation of hydrogel dispersion containing solid fatty acid Previous examples have illustrated a wide variety of hydrophobic oils can be incorporated into the hydrogel dispersions of the instant invention. Another class of useful materials are dispersed hydrophobic solids or waxy particles.

Some of the benefit agents within this class of materials are WO 98/08601 PCT/EP97/04751 43 moisturizing agents such as fatty acids, emollients, certain C6360 44 solid sunscreens such as P hydroxybenzoic acid, antimicrobial agents such as triclosan, and anti-acne agents such as salicylic acid.

This example illustrates the use of hydrogels to deliver such solid or waxy hydrophobic solids using a mixture of solid fatty acids as the specific example.

Preparation of hydrogel precursor solution 22 grams of a modified corn starch (Capsul (trademark) ex.

National Starch Chemical), 4.4 grams of Carrageenan (Gelcarin GP911 (trademark) ex. FMC) and 0.55 gram of sodium lauryl sulfate (ex BDH) were dissolved in 83.05 grams of deionized water at 800C. 210 grams of a molten fatty acid mixture containing 50 wt% of palmitic acid and 48 wt% of stearic acid was added to the above polymer solution and emulsified to form a fatty acid emulsion at 60 The fatty acid emulsion was then transferred to a Hobart Kitchen Aid mixer and mixed while cooling to form a viscous dough-like fatty acid emulsion. The emulsion comprised fatty acid particles with a size in the range of 1 to 40 tm in diameter.

The above composition then mixed with an equal amount of polymer solution containing 4% of Merquat 100 (ex. Calgon), of Chitosan (Sea Cure 340 ex. Protan) and 0.4 of acetic acid to form a hydrogel precursor solution containing dispersed fatty acid.

Preparation of hydrogel by extrusion 14 parts of the hydrogel precursor solution was then coextruded with 86 parts of the liquid cleanser of Table 3 using the method described in Example 3 to form hydrogel dispersion. This dispersion consisted of noodle shaped gel aj _I ;_I C6360 particles uniformly distributed in the surfactant composition.

Example 10. Further illustration of hydrogel dispersion containing solid fatty acid This example is very similar to the previous one except that a different gel forming polymer was employed.

Preparation of hydrogel precursor solution.

22 grams of a modified corn starch (Capsul ex. National Starch Chemical), 4.4 grams of Carrageenan (Gelcarin GP911 ex. FMC) and 0.55 gram of sodium lauryl sulfate (ex BDH) were dissolved in 83.05 grams of deionized water at 80 OC. 210 grams of a molten fatty acid mixture containing 50 wt% of palmitic acid and 48 wt% of stearic acid was added to the above polymer solution and emulsified to form a fatty acid emulsion at 60 "C.

The fatty acid emulsion was then transferred to a Hobart Kitchen Aid mixer and mixed while cooling to form a viscous dough-like fatty acid emulsion. The emulsion comprised fatty acid particles with a size in the range of 1 to 40 tm in diameter.

The above composition was then mixed with an equal amount of a polymer solution containing 10 wt% of fully hydrolyzed polyvinyl alcohol solution (Airvol 350 (trademark) ex. Air Product).

Preparation of hydrogel by extrusion 14 parts of the hydrogel precursor solution was then coextruded with 86 parts of the liquid cleanser of Table 3 using the method described in Example 3 to form hydrogel dispersion. This dispersion, consisted of noodle shaped gel particles uniformly distributed in the surfactant composition.

.b.

C6360 46 Example 11. Deposition of Fatty Acid from Liquid Cleanser The deposition of fatty acid onto pig skin was measured by a gas chromatograph method. A 5.08cm by 5.08cm (2 inches by 2 inches), piece of pig skin was first washed with about 0.35 grams of liquid cleanser for one minute. The treated pig skin was then rinsed with water for 50 seconds. The skin was dried once using a paper towel, air dried for two minutes and then extracted with 10 grams of heptane for-30 minutes. Aliquats of the heptane solution were injected into a GC to determine the amount of fatty acid deposited onto the skin. A control sample comprised 7 parts water, 7 parts of the fatty acid emulsion used to prepare the dispersions in Examples 9 and and 86 parts of the surfactant composition listed in Table 3- (also used to prepare Examples 10 and 11). The amount of fatty acid deposited from Examples 9 and 10, are compared with the control in Table 8. The result demonstrate that significant deposition of fatty acid occurs from these hydrogel dispersions. Furthermore, as with silicone oil, incorporating the fatty acid in the hydrogel formulation significantly increases its deposition (compare Examples 9 and with control).

Table 8. Deposition of fatty acid from hydrogel dispersions under conditions typical of skin cleansing.

Sample No.(a) Deposition of Fatty Acid pgg/cm2 Example 9 5.10 Example 10 4.2 Control(b) Note All sample contained 4 wt% fatty acid and the same fatty acid emulsion was used to prepare all the samples.

C6360 47 Note The control was prepared by mixing 7 parts of the fatty acid emulsion used to prepare Examples 9 and 10 with 7 parts of water first which is then mixed with 86 parts of the surfactant composition of Table 3.

Example 12. Preparation of hydrogel dispersion containing lipid A molten lipid solution was prepared-by heating 30 parts glycerol 15 parts Cholesterol (Cholesterol USP ex. Croda Chemicals LTD), 7.5 parts sugar ester (Ryoto S270 (trademark) ex. Mitsubishi-Kasei Foods Corp.) and 7.5 parts stearic acid (ex. Unichema International) on a 150 "C hot plate. The clear molten lipid solution was then cooled to about 98 OC and mixed with 10 parts of neutralized Aculyn 33 (ex. Rohm Haas, 2 wt%, pH: 7.5-8.0) solution and 30 parts of Carrageenan Gelcarin GP911 (trademark) solution (2 wt%) to form the hydrogel dispersion precursor containing Cholesterol.

The extrusion process described in Example 3 was used to prepare 17 wt% dispersion (2.55 wt% Cholesterol based on the total composition) of the hydrogel. Same surfactant system as Example 3 (Table 3) was used for the preparation. Deposition of Cholesterol from this cleansing composition was determined in Example 13. A comparative example containing 2.5 wt% Cholesterol uniformly dispersed in a liquid cleanser was prepared for comparison. The composition and the preparation process of this comparative example are given in Table 9 below WO 98/08601 PCT/EP97/04751 Table 9 Ingredient %a.i.

Cholesterol 2.50 Stearic Acid 1.25 Sucrose Ester 1.25 Glycerol 5.00 Genapol ZRO (SLES) 16.0 Sodium Lauryl Ether Sulfate Amonyl 380BA(CAPB) 2.00 Cocylamidopropylbetaine Jaguar C-13-S 0.25 NaC1 0.30 Water and minors to 100% Prenaration Melt glycerol, sucrose ester, stearic acid and cholesterol together on a hot plate. Premix the surfactants and the excess water. Add the surfactants to the lipid/glycerol mixture then add the Jaguar. Preserve the system and pH adjust to 5.3.

Adjust the viscosity using NaCl to 5000 mPas at 10s Example 13. Deposition of Cholesterol on skin The deposition of cholesterol onto pig skin from cleansing compositions was determined by the following method. 0.25 grams of cleanser was rubbed 50 times on a 5x5 cm 2 pig skin that was prewetted with tap water. The skin was then rinsed for seconds with deionized water and patted dry with a paper towel.

3 ml of ethanol was used to extract the cholesterol from the skin for analysis.

C6360 49 The amount of cholesterol extracted from the skin was determined by spectrophotometric method. The ethanol extraction was dried at 80 °C oven. 100 1tl methanol was added to the dried content. 1,000 .l aqueous cholesterol reagent from Sigma was added to the sample and left for 5 minutes to react with the extracted cholesterol. The aqueous cholesterol solution was then mixed with 500 tl chloroform and poured into microcentrifuge tubes. Chloroform was separated from the aqueous solution by cetrifuging the tubes at 13,000 rpm for 5 minutes. After centrifugation the top clear aqueous layer was pipetted into curvets and the absorbance at 500 nm was measured using a spetrophotometer and a standard calibration curve to determine the amount of cholesterol extracted from the skin.

The amount of cholesterol extracted from the skin treated with Example 12 are compared with two controls in Table The data shows that significant deposition of cholesterol was achieved from the hydrogel sample of Example 12 as compared to the two controls.

Table 10. Deposition of Cholesterol from shower gel Sample No. Deposition of Cholesterol cm2 Example 12 48.4 Control la 26.5 Control 2b 21.1 a. Control 1 is liquid cleanser contains 2.5 wt.% well dispersed cholesterol. The composition and preparation are given in'Table 9.

b. Control 2 is a liquid cleanser without containing any cholesterol. The amount of cholesterol given in the table is the cholesterol extracted from the pig skin.

WO 98/08601 PCT/EP97/04751 Example 14 A liquid cleanser containing 10 wt% of silicone hydrogel wt% silicone oil of the total composition) and 90 wt% of surfactant composition of Table 3 with 0.3 wt% instead of 0.97% Antil 141 was prepared using the process described in Example 3. The silicone hydrogel precursor solution containing 50 wt% 60,000 cps silicone oil, 0.47 wt% Carrageenan GP911, 0.155 wt% Aculyn-33, 0.31 wt% polyvinyl alcohol (Airvol 540 ex Air Product) and 24.06 wt% water was prepared the same way as described in Table 3. The hydrogel precursor solution contains silicone oil droplets with size in the range of 5 to micrometers.

Effect of the silicone hydrogel containing cleanser on consumer's after-use skin feel compared to the liquid cleanser without silicone hydrogel dispersion was evaluated using the protocol described below. The test site for this evaluation is the volar surface of the forearm. Hand and forearm were prewetted by holding under running tap water (30 OC) for approximately 15 seconds. 3.5 grams of the hydrogel containing liquid cleanser was then dispensed onto the hand and the assigned arm was washed for 20 seconds and rinsed under running water for 10 seconds. The forearm was patted dry with a paper towel. The procedure was repeated for the other arm using the same cleanser without containing the silicone hydrogel. All panelists were asked to determine their perception of after use skin feel. 7 out of the 8 panelists felt a difference in afteruse skin feel and 5 out of those 7 preferred the skin feel of the arm treated with the silicone hydrogel containing liquid cleanser.

C6360 51 Example 15: Preparation of hydrogel dispersions as skin lotions This example showed that hydrogel dispersions can be prepared using aqueous solution composition suitable for skin care application. In this example an aqueous solution composition containing 0.9 wt% Natrosol 250 HHR (hydroxyethylcellulose ex.

Aqualon), 0.06 wt% Carbopol C981 (ex. BF Goodrich), 0.4 wt% Na3PO4 and 0.05wt% Glydant Plus without any surfactant was prepared for hydrogel preparation.

A petrolatum hydrogel precursor solution was formed by mixing 10 parts of petrolatum (Snow White (trademark) ex.

Penreco) to 90 parts of aqueous polymer solution containing 0.6 wt% chitosan (Seacure 343 ex. Protan), 0.4 wt% acetic acid and 1.8 wt% Jaguar C13S (Rhone-Poulenec) at 60 oC, 300 rpm for minutes using an overhead mechanical stirrer. The emulsion so prepared contained petrolatum droplet with size in the range of 1 to 30 pim. 25 parts of the petrolatum hydrogel precursor solution was injected into 75 parts of aqueous solution composition to form elongated hydrogel noodles using #14 gauge syringe needle. The aqueous composition containing the petrolatum hydrogel noodles were then passed through a screen having mesh size 200 Lm to form the hydrogel dispersions. This sample contained large soft hydrogel particles concentrated with petrolatum droplets and is suitable for skin care application.

Example 16: Effect of Process Condition on Hydrogel Formation This example showed that formation of hydrogel particles depends on the mixing device used to incorporate the hydrogel precursor solution into the aqueous solution composition. The preferred process, extrusion/low-shear mixing process, provides a better control on the hydrogel particle size and has better retention of water insoluble benefit agent inside the hydrogel C6360 52 particles.

A silicone hydrogel precursor solution was prepared by mixing parts of 60,000 cps silicone oil in 70 parts of polymer solution containing 0.4 wt% Seacure 343, 0.2 wt% acetic acid and wt% Jaguar C13s at 60 rpm for 7 minutes using an overhead mechanical mixer. The silicone emulsion so prepared contained wt% silicone oil with particle size about 132 p.m.

Two aqueous liquid cleansers with different viscosity were prepared for hydrogel processing. These two aqueous solution composition with composition shown in Table 11 all contained 17.5 wt% surfactants thickened with 0.4 wt% Carbopol ETD2020 and 0.4 wt% Bentone. The viscosity of these two cleanser was 15,000 cps and 3,500 cps respectively and had a pH around 7.8.

Two processes, a batch process and a coextrusion/in-line mixing process, were used to make large hydrogel dispersions in these two liquid cleansers.

In the batch process, 15 parts of above silicone hydrogel precursor solution was added to 85 parts of liquid cleanser and mixed at 60 rpm for 15 minutes using an overhead mixer. The equipment described in example 3 was used for the coextrusion/in-line mixing process. 15 parts of silicone hydrogel precursor solution was coextruded with 85 wt% of the liquid cleanser through the two fluid nozzle to form elongated soft hydrogel noodles. The prehardened hydrogel noodles were then continuously passed through a low shear in-line mixing device at the rate of 20 cc/minute to break the hydrogel noodles into hydrogel particles. Two different in-line mixing devices were used to break the hydrogel noodles. One is a static in-line mixer with 0.64 cm in diameter and 15.2 cm in length. The other in-line mixer containing two identical screens having mesh size about 200 tm. Both the hydrogel particle size and of silicone oil retained inside C6360 53 the hydrogel gel particles were shown in table 12. The results clearly showed that the coextrusion/in-line mixing process had much better control on the size of hydrogel particles and also provided much better entrapment of oil inside the formed hydrogel particles during the process than the direct mixing batch process.

Table 11: Liquid cleanser comDosition of ExamDle 16 Raw Material Tergobetaine F (trademark) low viscosity liquid cleanser 26.7% high viscosity liquid cleanser Goldschmidt 26.7% Standapol EA- Henkel 18.0% 18.0% 2L (trademark) Jodapon CI-ADH PPG-Mazer 5.8% 5.8% (trademark) DC3501 Dow Corning 1.0% silicone wax Bentone Clay Rheox 0.4% 0.4% Carbopol BF Goodrich 0.45% 0.45% ETD2020 Glycerine Fisher 2.5% Isopropanol 2.0% 0% Perfume Givaudan- 1.0% Roure Glydant Plus Lonza 0.2% 0.2% DI Water to 85% to 06360 54 Table 12: Hydroorel poarticle size and oil retained of exarnle Low Viscosity High Viscosity Liquid Cleanser Cleanser Gel Size Oil Gel Size %Oil. Retaine Retained Direct Mixing 392 j rn 68% >710 tun 41% Coextrusion! 230 ~m 85% -140 ptm Static Mixer Coextrusion/ 306 pm 88% 326 ptm 84% Screen

Claims (2)

1. An aqueous composition comprising:

40-95% by weight of an aqueous solution containing 5-50% surfactant and having a viscosity greater than 300 centipoises; and 5% to 60% by wt. of a hydrogel composition comprising: 0.1 to 30% by wt. hydrogel composition of at least one polymer soluble in water which polymer is insolubilized when placed in the aqueous solution of item (ii) 0.2 to 30% by wt. hydrogel composition of a polymer soluble in water, and soluble or dispersible in the aqueous solution of item and (iii) 1.0 to 60% water insoluble benefit agent entrapped in a network formed by and (ii); wherein the particles of the benefit agent (iii) have particle size of 0.2 to 200 micrometers; wherein the hydrogel is greater than 25 micrometers; wherein the size of the hydrogel is greater than that of the benefit agent, and wherein the hydrogel comprising composition is formed by injecting a hydrogel precursor solution into the aqueous solution or by co- extruding the hydrogel precursor solution in the aqueous solution. 2. A composition according to claim 1, wherein polymer of is insolubilized, when contacted with the aqueous solution of item by thermal gelation. 3. A composition according to claims 1 or 2, wherein said gel forming polymer is selected from the group consisting of gel forming polysaccharides, such as, for example, carrageenan or agar, gel forming proteins such as, for example, gelatin, and thermally gelling synthetic polymers. AMENOD2D 3HEET C6360 56 4. A composition according to any of claims 1 to 3, wherein said gel forming polymer is a synthetic polymer selected from the group consisting of N-acrylamides and homo or copolymers of polyacrylate or methacrylate containing polymers incorporating an acrylic or methacrylic ester of a long chain branched or straight chain alcohol. A composition according to any of claims 1 to 4, wherein polymer of is insolubilized, when contacted with the aqueous solution of item by precipitation or coacervation, wherein precipitation or coacervation is preferably caused by a change in pH, and wherein polymer (i) sensitive to pH of aqueous solution is preferably polyglucosamine. 6. A composition according to claim 1, wherein precipitation or coacervation is caused by a change in electrolyte concentration, wherein polymer sensitive to electrolyte concentration of aqueous solution is preferably selected from polyvinyl alcohol having MW greater than 13,000 and degree of hydrolysis 78% to 100%; and hydroxyalkylcellulose. 7. A composition according to claim 1, wherein polymer of is in-solubilized by cross-linking with a cross-linker present in the aqueous solution of item 8. A composition according to claim 1, wherein property modifying polymer (ii) is selected from the group consisting of: carboxylic acid containing acrylic polymers; nonionic polymers selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, modified corn starch and hydroxyalkyl cellulose or hydroxylalkylmethyl cellulose; and ArMiL-v.. C6360 57 cationic polymers. 9. Use of a composition according to any preceeding claim in a personal cleansing or skin care cream or product A process for preparing an aqueous composition comprising hydrogel particles having the following composition: 0.1 to 30% by wt. hydrogel-composition of at least one polymer soluble in water which polymer is insolubilized when placed in said aqueous solution; 0.2 to 30% by wt. hydrogel composition of a polymer soluble in water and soluble or dispersible in the aqueous solution; and 1.0 to 60% water insoluble benefit gel entrapped in a network formed by and wherein said particles of benefit agent have particle size of 0.2 to 200 micrometers; wherein said hydrogel is greater than 25 micrometers; and wherein the size of the hydrogel is greater than that of the benefit agent; wherein the process comprises the steps of:- dissolving polymer and to form a polymer solution in water; (ii) dispersing component into the polymer solution to form a hydrogel precursor solution; C6260 58 (iii) formulating an aqueous solution comprising 40-95% by weight of an aqueous solution containing 5-50% surfactant and having a viscosity greater than 300 centipoises, such that first polymer is not soluble and second polymer (b) is soluble or dispersible in the aqueous solution; (iv) combining the hydrogel precursor solution and the aqueous solution by injecting the hydrogel precursor solution into the aqueous solution or co-extruding the hydrogel precursor solution in the aqueous solution to form elongated hydrogel noodles which form when the hydrogel precursor contacts the aqueous solution, the noodles being sufficiently rigid to entrap benefit agent yet sufficiently soft to readily rupture when applied to a substrate; and breaking said noodles into particles by means of a mechanical mixer in line mixer. 11. A process according to claim 10, wherein the insolubilization of first polymer is caused by thermal gelation, precipitation or coacervation, or cross linking. L