Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/0052—Preparation of gels
  • B01J13/0065—Preparation of gels containing an organic phase

Definitions

• 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 ⁇ e.g., liquid cleanser containing the hydrogel particles).
• Gel particles with controllable size and controllable gel strength are prepared simply by first adding (e.g.
• 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.
• One method used for enhancing delivery of benefit agents (e.g., silicone and vegetable oil) to the skin or hair is through the use of cationic hydrophilic polymers such as Polymer JR (RI from Amerchol or Jaguar"" from Rhone Poulenc. This method is disclosed, for example, in EP 93,602; WO
• both the deposition polymer and the generally small sized silicone particles are uniformly distributed throughout the entire liquid cleanser composition (i.e there are no concentrated "pockets" of benefit agent) .
• hydrophilic polymers are themselves incorporated into liquid cleansers or aqueous solutions to provide various benefits.
• hydrophilic polymers such as guar gum, polyacrylamides , polyacrylic acid and polymer JR ,RI 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.
• the polymers are uniformly incorporated or distributed throughout the entire surfactant composition to provide the claimed benefits.
• the level of deposition of the benefit 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.
• a polymer agent typically, a cationic deposition agent such as a cationic guar
• 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.
• the separate hydrogel particles enhance the cleanser's in-use sensory properties (i.e., smooth and creamy feel) when the cleanser or aqueous composition generally is rubbed on the skin.
• U.S. Patent No. 5,089,269 to Noda et al . 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.
• similar problems occurred, as described in the patent, when the improved capsule was smaller than 100 urn or larger than 1000 urn.
• 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 u 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 s large.
• U.S. Patent Nos. 4,777,089 and 4,908,223, to Takizawa disclose icrocapsule 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.
• 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.
• 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 (e.g., smooth, rich, creamier feel) to the composition.
• the aqueous composition comprises:
• 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
• 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;
• hydrogel composition of at least a second polymer which is soluble in water and either soluble or dispersible in said aqueous solution; and (m) 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 d) and (n); 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.
• sa d 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.
• 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.
• polymer of d) is insolubilised, when contacted with the aqueous solution of item (a), by precipitation or coacervation, which is generally caused by a change in pH .
• the polymer d) will be polyglucosamine .
• precipitation or coacervation is caused by a change in electrolyte concentration.
• polymer (i) is selected from the group consisting of polyvmyl alcohol having MW greater than 13,000 and a degree of hydrolysis of from 78% to 100%; and hydroxyalkylcellulose .
• the polymer of d) is solubilised by cross- linking with a cross-lmker present in the aqueous solution (a) .
• the cross- linker is potassium ion.
• the cross-linker is calcium ion.
• the cross-linker is borax
• polymer (n) selected from the group consisting of:
• non-ionic polymers selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, modified corn starch and hydroxylalkyl cellulose or hydroxyalkylmethyl cellulose;
• the aqueous composition containing the novel hydrogel particles is prepared first by adding (e.g., injecting) a polymer solution containing the said two polymers and the water insoluble material into the said aqueous medium to form elongated (m theory- there is no limit to the size of the noodle since it can be continuously extruded), soft (i.e., 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:
• the second polymer or polymers (2) (b) forming the hydrogel composition is a property modifying polymer which is required (1) to help stabilize benefit agent in the polymer hydrogel system and (2) 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 m personal cleansing and, in particular, skin care creams and products.
• Figure 1 shows the effect of carrageenan (one of possible network forming polymers (2) (a) which msolubilize 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 (2) (b) which are soluble both in water and in aqueous medium) , an acrylic polymer, is combined with carrageenan.
• Acrysol one of possible property modifying polymers (2) (b) which are soluble both in water and in aqueous medium) , an acrylic polymer, is combined with carrageenan.
• the present invention relates to hydrogel compositions which are uniformly dispersed and stably suspended in aqueous compositions designed for personal cleansing or skin care applica ions.
• the hydrogel composition exists in the aqueous solution as a separate polymer gel phase (i.e., formed when at least one polymer network forming polymer msolubilizes 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 (i.e, having a particle size greater than 25 micrometers, preferably greater than 100 micrometers, up to about several centimeters).
• these domains are capable of trapping water insoluble agents, hereafter designated the "benefit agent", within the gel structure, i.e., 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.
• 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.
• 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 emulsion or dispersion.
• hydrogel precursor solution 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 (2) (a) and (2) (b) 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 (2) (a)) upon 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 ⁇ n- line mixer or an m-lme 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.
• hydrogel compositions of larger size.
• the size of the hydrogel domains e.g., particles
• the diameter may be as high as several centimeters. Inn ection/ low shear mixing processes are preferred for making the hydrogel particles
• the hydrogel precursor solution is injected to or co-extruded simultaneously with the aqueous solution to form elongated soft hydrogel noodles.
• the noodles have no upper size limit as they are extruded.
• 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.
• the prehardened hydrogel noodle is too rigid then the hydrogel noodles tend to plug the m-lme 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.
• the hydrogel noodle's rigidity can be reduced by reducing the amount of network forming polymer (2(a)) or increasing the level of property modifying polymer (2(b)) 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.
• the hydrogel and aqueous composition comprising such comprise three essential components: I) a hydrogel forming polymer system (comprising a first polymer which solubilizes 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); li) a water insoluble benefit agent (components (i) and (n) together form the "hydrogel" composition when formed in the aqueous solution composition dii)); and, iii) an aqueous solution composition capable of suspending the hydrogel and maintaining its integrity due to insolubility of first polymer.
• a hydrogel forming polymer system comprising a first polymer which solubilizes 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
• li) a water insoluble benefit agent components (i) and (n) together form the "hydr
• the hydrogel structure or composition comprises (i) a hydrogel forming polymer system (containing at least two polymers) and (n) a water insoluble benefit agent.
• Polymer systems useful for forming hydrogels (component d) above) with desirable properties comprise in turn (a) a first polymer which is soluble in water but msolubilizes when placed in an aqueous solution composition (component (ui) above); and (b) a second property modifying polymer which ensures the final hydrogel composition is not so strong that it will not disintegrate smoothly when the hydrogel s applied to a substrate, e.g., skin, and but still has sufficient gel strength to retain the benefit agent during processing and storage.
• a substrate e.g., skin
• polymers (a) and (b) form a web or network which retains the benefit agent.
• polymers (a) and (b) and the mechanism whereby polymer (a) is insolubilized in the surfactant composition are discussed in greater detail below.
• 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 (lii). This msolubilization is accomplished using one of the following solubilization mechanisms:
• Thermal gel a tion Suitable polymers that exhibit this type of gelling behavior 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: l) 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 Gelcar GP911, and Gelcarin 379; n) gel forming proteins.
• Particularly preferred gel forming proteins are gelatins.
• Suitable gelatins include Gelatin G 9382 and G 2625 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.
• 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.
• 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 properties of the aqueous solution such as, for example, the pH or electrolyte concentration.
• a particularly suitable pH sensitive polymer is Chitosan (polyglucosam e) or its various chemically modified variants.
• Particularly useful chitosans are those sold by Pronova Biopolymers under the trade name Seacure 343, and Seacure 443.
• Chitosan has 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.
• electrolyte sensitive 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.
• the same polymer may be in either class (2) (a) (i.e., soluble, but insolubilized upon contact with aqueous surfactant solution); or class (2) (b) (i.e., soluble in both water and aqueous surfactant solutions) depending on what else is in the aqueous solution.
• a polymer sensitive to electrolyte concentration might be a class (2) (b) polymer in a composition without electrolyte, but become a class (2) (a) polymer in an aqueous surfactant solution containing sufficient electrolyte to insolubilize the polymer.
• the polymer may be a (2) (b) polymer, but, if present, the polymer becomes a (2) (a) polymer.
• 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 (e.g., 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.
• 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.
• the polymers described above are essential to form the hydrogel as they provide the backbone network without which the hydrogel composition can not exist.
• these polymers alone are usually too rigid to provide a smooth rub- in 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.
• 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 .
• 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.
• 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.
• nonionic polymers such as polyvinyl alcohol from Air Products sold under the trade name Airvol, polyvinyl 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 m) 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/d
• the second component of the "hydrogel” composition is the benefit agent (component (n) above). This is described n greater detail below.
• 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, e.g., to the skin, hair or teeth
• 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 o ls, gums and modifica ions thereof such as linear and cyclic polydirnethylsiloxanes , ammo, ⁇ lkyl 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 mynstic acid glyce ide and 2- ethylhexanoic acid glyceride, c) waxes such as carnauba, spermaceti beeswax, lanolin and derivatives thereof, d) hydrophobic plant extracts, e) hydrocarbons such as liquid paraffins, petrolatum, microcrystall e wax,
• sunscreens such as octyl methoxyl cmnamate (Parsol MCX) and butyl methoxy benzoylmethane (Parsol 1789);
• m) Phospholipids such as lecithins;
• antimicrobial such as 2-hydroxy-4 , ' , 4 ' - trichlorodiphenylether (DP300) and 3,4,4'- trichlorocarbamlide (TCC), and mixtures of any of the foregoing components
• water soluble materials e.g., glycerin, enzyme, -hydroxy acid
• 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 pre- emulsifymg 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 wt . % , preferably 10 to 40 by wt .
• the size of the benefit agent particle can vary from 0.2 micrometer up to several hundred micrometers.
• the paicicle size of benefit agent is preferably in the range of 5 to 150 micrometers
• the invention comprises an aqueous solution composition comprising the hydrogel composition more fully defined above.
• the liquid ⁇ omposition itself s described in greater detail be low
• the invention rel ⁇ es to the aqueous solution composition in which the hydrogel incorporating the benefit agent (i.e., containing the agent m a web produced by polymers (2) (a) and (2) (b) ) is di persed.
• the aqueous solution composition can comprises from about 0% to about 60 wt%, pr ferably 2% to 40 wt% of surfactants selected from any m surfactants suitable for personal care or cleansing applications. In general, for personal cleansing application higher level of surfactants typically m 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-sur actant skin lotion compositions are contemplated.
• the aqueous solution composition should be formulated in such a way that the first water s oluble polymer becomes insoluble upon contact with t e 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 the hydrogel compositions under the action oi 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 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 m the composition or by the careful selection and combination of surfactants. Both methods are well known in the art.
• U.S. Patents 4,912,823, 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
• 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 lsethionate of formula RCO CH CH SO,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.
• RCO CH CH SO,M fatty acyl lsethionate of formula RCO CH CH SO,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.
• RCO CH CH SO,M fatty acylsethionate of formula RCO CH CH SO,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 atom
• 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 .
• anionic detergents include alkyl glyceryl ether sulphate, sulphosuccinates , taurates, sarcosmates , sulphoacetates, alkyl phosphate, alkyl phosphate esters and acyl lactates, alkyl glutamates and mixtures thereof.
• Sulphosuccinates may be monoalkyl sulphosuccinates having the formula: R ; O 2 CCH 2 CH ( S0,M) C0 2 M; and amido-MEA sulphosuccinates of the formula:
• Sarcosinates are generally indicated by the formula: R-'CON(CH ( )CH 2 C0 2 M, wherein R 5 ranges from C -C , alkyl, preferably C ]: -C alkyl.
• Taurates are generally identified by the formula:
• alkylethoxy carboxylate indicated by the following formula: R 5 (0CH 2 CH 2 ) n C00M, wherein R ' ranges from C-C 20 alkyl, preferably C 12 -C,, 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 (e.g., 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
• primary and secondary alcohol ethoxylates especially the C P . _. r aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol.
• the surface active agent is preferably present at a level of from 1 to 35 wt . % , preferably 3 to 30 w . % .
• 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.
• R 1 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
• Y is -C0 2 - or -SO-,-.
• Zwitterionic detergents within the above general formula include simple betaines of formula: R 2
• R 1 , R 2 and R 3 are as defined previously.
• R 1 may, in particular, be a mixture of C , and C ] 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 .
• compositions of the invention may be formulated as products for washing the skin or hair, e.g , 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.
• compositions of the invention will generally be pourable liquids or semi liquids e.g., pastes and will preferably have a viscosity in the range 1500 to 100,000 mPas measured at a shear rate of 10s ] at 25°C a Haake Rotoviscometer RV20.
• compositions include opacifiers, preferably 0.2 to 2.0 wt . % ; preservatives, preferably 0.2 to 2.0 wt . % and perfumes, preferably 0.5 to 2.0 wt . %.
• the invention relates to a process for preparing an aqueous solution comprising hydrogel particles wherein said hydrogel particles have the following composition:
• hydrogel composition of at least one polymer soluble in water which polymer is insolubilized when placed in an aqueous medium;
• hydrogel composition of a polymer soluble in water, and soluble or dispersible in aqueous surfactant solution
• Example 1 Preparation of hydrogel dispersions (i.e., hydrogel composition) containing silicone oil by a direct mixing process .
• 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 techniques we have found useful take advantage of rapid gelation or cross-lmkmg that occur for certain types of water soluble polymers when their solution environment changes, e.g., a change in pH, ionic strength, temperature, type of ion, presence of cross-linker, etc.
• 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 sol ution ) with a liquid cleanser using conventional mechanical stirrer.
• 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 (1) first polymer which msolubilizes when added to aqueous surfactant solution; (2) second property modifying polymer and (3) benefit agent), which itself is water continuous, does not first dissolve in the cleansing composition but rather forms a discrete dispersed aqueous phase.
• a 40% emulsion of silicone oil (60,000 centistokes, ex Dow Corning) was formed by mixing 40 parts of the silicone oil to 60 parts of aqueous polymer solution which contained 1 wt% of Chitosan (first polymer) (Sea Cure 340 ex Protan), 0.8 wt% of acetic acid and 3 wt% of hydroxyl ethylcellulose (second polymer) (Natrosol 250 MR ex. Aqualon) at 400 rp 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 -m to 50 :m dispersed m the polymer solution.
• compositions of Examples 1A and IB are detailed in Table 2 along with some of their physical properties.
• 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.
• first polymer Chitosan
• second polymer a cationic guar polymer
• hydrogel dispersions useful for the purposes of the present invention can also be prepared by a coextrusion process.
• the example illustrates compositions that are prepared by co-extrudmg 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.
• 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 conjunction with a great variety of materials as will be shown in subsequent examples.
• Silicone oil was mixed with an aqueous solution of a neutralized carboxyl acid containing acrylic copolymer (second polymer) (Aculyn-33, Rohm & Haas) in an aqueous solution with a pH in the range of 7 to 7.5 by mechanical stirring.
• Aculyn-33 was used as the property modifying polymer.
• the oil droplet size which varied from 5 to 150 :m in diameter, was controlled by the concentration of Aculyn-33 and the stirring speed. Higher concentration and faster stirring led to smaller oil droplets.
• aqueous 6-carrageenan (Gelcarin GP-911, FMC) solution the first polymer (network forming polymer)
• FMC aqueous 6-carrageenan
• two hydrogel precursor dispersions were prepared that differed in the size of the silicone oil droplets.
• the silicone oil droplet size was the range ot 2-30 :m while in the second dispersion the droplet size fell within 40 -100 :m.
• 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 40 ex Harvard Apparatus) .
• a cool (room temperature ⁇ 22 °C) 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 w . % silicone oil .
• Example 3A and Example 3B 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 :m in diameter suspended m the shower gel composition of Table 3
• Footnote 1 Adjust pH to 5.24 " 0.1 with NaOH
• Footnote 2 Cross-linked polyacrylic acid
• Footnote 3 Polyethylene glycol propylene glycol oleate
• Aculyn is neutralized carboxyl acid containing acrylic copolymer.
• 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 network- forming (first) and property modifying (second) polymers.
• a series of model hydrogel particles were prepared by a cross-lmkmg method using carrageenan as the network polymer and potassium ions as the cross-lmkmg agent
• the dispersions were made by a variant of the extrusion process described in Example 3 using an aqueous solution of KCl 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 :m.
• An Instron (Model 1122) was found to be a suitable instrument to differen iate 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 10 Newton load was lowered until it came in contact w th 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 ⁇ b
• 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-lmkmg with PT is shown in Figure 2. The results indicate that the gel strength decreased significantly with increasing Acrysol concentration even though the total concentration of polymer increased.
• Hydrogels containing carrageenan and Acrysol i n ci weight ratio ranging from 3:1 to 2.1 were capable of effectively trapping benefit agents such as emulsified emollient oil e.g., silicone oil, and yet rubbed smoothly into the skin without noticeable grit.
• benefit agents such as emulsified emollient oil e.g., silicone oil
• Example 5 Deposition of silicone oil on skin ex-vivo.
• test composition A 0.5 ml aliquot of the test composition was applied to 2 ' by 2" square strips of excised pig skin that had first been prewetted with tap water at 37 °C .
• the composition was lathered for 10 seconds and then rinsed for 10 seconds undei 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 .
• 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 ot 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.
• 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.
• hydrogel dispersions can be prepared with a variety of polymers provided they possess the required hydrogel forming capabilities and gel strengths.
• a cationic polymer Chitosan a cationic polymer Chitosan
• first polymer (Seacure 343 ex. Pronova Biopolymer) was used as the network forming polymer and a cationic modified guar
• 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 propylbetame at 300 rprn for 15 minutes using an overhead stirrer.
• the resulting emulsion contained silicone oil droplets with size ranging from 2 :m to 60 :m dispersed in the polymer solution .
• Example 3 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 :m.
• Example 6 (this example) shown in Table 6
• the deposition tests were carried out according to the method described 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.
• 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.
• 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.
• hydrogel dispersion of this instant invention 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 (2-Ethylhexyl-P-Methoxy Cinnamate) . These examples illustrates the use of hydrogels to deliver such hydrocarbon oils deliver such hydrocarbon oils.
• Example 3 The extrusion process described in Example 3 was used to prepared 12.5 wt% dispersion of the hydrogels containing 100% petrolatum, 50%Isopropyl palm ⁇ tate/50 % petrolatum, and 50% Parsol MCX/50% petrolatum respectively foi 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
• 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 moisturizing agents such as fatty acids, emollients, certain
• 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.
• 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 :m in diameter .
• composition then mixed with an equal amount of polymer solution containing 4% of Merquat 100 (ex. Calgon), 0.5 % of Chitosan (Sea Cure 340 ex. Protan) and 0.4 % of acetic acid to form a hydrogel precursor solution containing dispersed fatty acid.
• hydrogel precursor solution 14 parts 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,
• 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.
• 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 :m m 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 ex. Air Product).
• hydrogel precursor solution 14 parts 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 m the surfactant composition.
• 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 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 skm.
• a control sample comprised 7 parts water, 7 parts of the fatty acid emulsion used to prepare the dispersions m Examples 9 and 10 and 86 parts of the surfactant composition listed in Table 3 (also used to prepare Examples 10 and 11).
• a molten lipid solution was prepared by heating 30 parts glycerol , 15 parts Cholesterol (Cholesterol USP ex. Croda
• Example 3 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%
• 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 10 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 . The amount of cholesterol extracted from the skin was determined by spectrophotometric method. The ethanol extraction was dried at 80 °C oven. 100 :1 methanol was added to the dried content. 1,000 :1 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 :1 chloroform and poured into microcentrifuge tubes. Chloroform was separated from the aqueous solution by cetrifug g the tubes at 13,000 rpm for 5 minutes. After centri fugation 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 10.
• the data shows that significant deposition of cholesterol was achieved from the hydrogel sample of Example 12 as compared to the two controls.
• Control 1 is liquid cleanser contains 2.5 wt . % well dispersed cholesterol.
• the composition and preparation are given in Table 9.
• 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.
• a liquid cleanser containing 10 wt% of silicone hydrogel (5 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 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 Table 3.
• the hydrogel precursor solution contains silicone oil droplets with size m the range of 5 to 60 micrometers .
• hydrogel dispersions can be prepared using aqueous solution composition suitable for skin care application.
• aqueous solution composition containing 0.9 wt% Nitrosol 250 HHR (ex. Aqualon) , 0.06 wt% Carbopol C981 (ex. BF Goodrich), 0.4 wt% Na3P04 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 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%
• the emulsion so prepared contained petrolatum droplet with size m the range of 1 to 30 u . 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 um to form the hydrogel dispersions. This sample contained large soft hydrogel particles concentrated with petrolatum droplets and is suitable for skin care application.
• 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 particles .
• a silicone hydrogel precursor solution was prepared by mixing 30 parts of 60,000 cps silicone oil m 70 parts of polymer solution containing 0 4 wt% Seacure 343, 0.2 wt% acetic acid and 2.0 wt% Jaguar C13s at 60 rpm for 7 minutes using an overhead mechanical mixer.
• the Jilicone emulsion so prepared contained 30 wt% silicone oil with particle size about 132 um.
• 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.

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