[0001] The present invention relates a multistage polymer. More specifically, the present invention relates to a multistage polymer having (a) a first stage polymer comprising: (i) structural units of a monoethylenically unsaturated first stage monomer; (ii) structural units of a multiethylenically unsaturated first stage monomer; and (iii) structural units comprising a pendant absorbing group selected from the group consisting of a phosphorus acid group, phosphorus acid full-ester group and mixtures thereof; wherein the first stage polymer has a glass transition temperature in the range of -60 °C to 35 °C; and (b) a second stage polymer having a glass transition temperature in the range of 40 to 100 °C; wherein the second stage polymer incompletely encapsulates the first stage polymer.

[0002] Polymers containing phosphoms acid moieties have found utility in many applications including coating, adhesives and skin care. The phosphorus acid moieties provide improved adhesion of the polymer to metal substrates, form crosslinks in the presence of divalent metal ions and promote adsorption of the polymer to pigment particles such as titanium dioxide to form composite particles.

[0003] There is an increasing market trend in skin care to expand the use of inorganic UV filters in sunscreen formulations. Inorganic metal oxide particles, such as titanium dioxide, provide adsorption of UVA and UVB radiation and to this end are conventionally incorporated in sunscreen formulations. Inorganic metal oxides, however, can cause negative aesthetic qualities such as poor sensorial feel and undesirable white appearance, both of which are believed to be the result of undesirable agglomeration of the inorganic metal oxide particles and poor distribution onto the skin.

[0004] An approach to facilitating the incorporation of inorganic metal oxides in skin care compositions is disclosed in W02017058404 to Joshi et al. Joshi et al. disclose a skin care composition comprising: (a) copolymer particles comprising, based on the total weight of the copolymer particles, polymerized units derived from (i) 0.1 to 20 weight % of phosphoms acid monomers, and (ii) 80 to 99.9 weight % of comonomers; (b) voided latex particles comprising: (i) at least one core polymer comprising polymerized units derived from (a) 20 to 60 weight % of monoethylenically unsaturated monomers containing at least one carboxylic acid group, based on the total weight of the core polymer(s), and (b) 40 to 80 weight % of non-ionic ethylenically unsaturated monomers, based on the total weight of the core polymer(s); and (ii) at least one shell polymer comprising polymerized units derived from (a) 55 to 85 weight % of non-ionic ethylenically unsaturated monomers, based on the total weight of the shell polymer(s), and (b) 15 to 45 weight % of polyethylenically unsaturated monomers, based on the total weight of the shell polymer(s), wherein the voided latex particles contain a void and have a particle size of from 50 nm to 1000 nm; (c) inorganic metal oxide particles; and (d) one or more dermatologically acceptable carriers. [0005] Notwithstanding, there remains a continuing need for multistage polymers that facilitate uniform incorporation of inorganic materials into aqueous formulations, in particular skin care formulations.

[0006] The present invention provides a multistage polymer, comprising: (a) 1 to 30 wt%, based on weight of the multistage polymer, of a first stage polymer comprising: (i) 59.9 to 99.8 wt%, based on weight of the first stage polymer, of structural units of a monoethylenically unsaturated first stage monomer; (ii) 0.1 to 40 wt%, based on weight of the first stage polymer, of structural units of a multiethylenically unsaturated first stage monomer; (iii) 0.1 to 20 wt%, based on weight of the first stage polymer, of structural units comprising a pendant absorbing group selected from the group consisting of a phosphorus acid group, phosphoms acid full -ester group and mixtures thereof; wherein the first stage polymer has a glass transition temperature in the range of -60 °C to 35 °C; and (b) 70 to 99 wt%, based on weight of the multistage polymer, of a second stage polymer having a glass transition temperature in the range of 40 to 100 °C, wherein the second stage polymer is substantially free of pendant absorbing groups selected from phosphorus acid groups and phosphorus acid full-ester groups; wherein the second stage polymer incompletely encapsulates the first stage polymer.

DETAILED DESCRIPTION

[0007] We have now found that multistage polymers, as described herein, facilitate the formulation of aqueous skin care compositions containing inorganic materials with causing negative aesthetic qualities. Specifically, the use of multistage polymers, as described herein, facilitate the formulation of aqueous skin care compositions containing inorganic materials (e.g., titanium dioxide) without degradation in the sensorial feel of the skin care composition or undesirable white appearance on application of the composition to skin while maintaining desired sunscreen performance against UVA and UVB ration.

[0008] Unless otherwise indicated, ratios, percentages, parts, and the like are by weight. [0009] As used herein, unless otherwise indicated, the terms "weight average molecular weight" and "M _w " are used interchangeably to refer to the weight average molecular weight as measured in a conventional manner with gel permeation chromatography (GPC) and conventional standards, such as polystyrene standards. GPC techniques are discussed in detail in Modem Size Exclusion Liquid Chromatography: Practice of Gel Permeation and Gel Filtration Chromatography, Second Edition, Striegel, et al., John Wiley & Sons, 2009. Weight average molecular weights are reported herein in units of Daltons.

[0010] The term "polymer" as used herein and in the appended claims refers to a compound prepared by polymerizing monomers, whether of the same or a different type. The generic term "polymer" includes the terms "homopolymer," "copolymer," and "terpolymer."

[0011] Percentages of monomer units in a polymer are percentages of solids or neat monomer weight, i.e., excluding any water present in a polymer emulsion.

[0012] The term "cosmetically acceptable" as used herein and in the appended refers to ingredients typically used in personal care compositions, and is intended to underscore that materials that are toxic when present in the amounts typically found in personal care compositions are not contemplated as part of the present invention.

[0013] The term "structural units" as used herein and in the appended claims refers to the remnant of the indicated monomer; thus a structural unit of ethyl acrylate is illustrated: where the dotted lines represent the points of attachment to the polymer backbone.

[0014] The term “glass transition temperature” or “T _g ” as used herein and in the appended claims means the temperature at or above which a glassy polymer will undergo segmental motion of the polymer chain. Glass transition temperatures of a polymer can be estimated by the Fox equation [Bulletin of the American Physical Society 1, 3 Page 123 (1956)] as follows:

For a copolymer, Wi and W2 refer to the weight fraction of the two comonomers, and T _g(1) and T _g(2) refer to the glass transition temperatures of the two corresponding homopolymers in degrees Kelvin. For polymers containing three or more monomers, additional terms are added (W _n /T _g(n) ). The T _g of a polymer phase can also be calculated by using the appropriate values for the glass transition temperatures of homopolymers, which may be found, for example, in “Polymer Handbook”, edited by J. Brandrup and E. H. Immergut, Interscience Publishers. The values of T _g reported herein are calculated based on the Fox equation. [0015] The term "aesthetic characteristics" as used herein and in the appended claims in reference to an acidic aqueous cleansing formulation refers to visual and tactile sensory properties (e.g., smoothness, tack, lubricity, texture, color, clarity, turbidity, uniformity). [0016] Preferably, the multistage polymer of the present invention (preferably, for use in personal care formulations in combination with inorganic particles having a hydrophilic surface treatment), comprises: (a) 1 to 30 wt% (preferably, 4 to 25 wt%; more preferably, 5 to 20 wt%; most preferably, 7.5 to 15 wt%), based on weight of the multistage polymer, of a first stage polymer comprising: (i) 59.9 to 99.8 wt% (preferably, 84.5 to 98.5 wt%; more preferably, 87.25 to 97.25 wt%; most preferably, 88 to 93 wt%), based on weight of the first stage polymer, of structural units of a monoethylenically unsaturated first stage monomer; (ii) 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of a multiethylenically unsaturated first stage monomer; (iii) 0.1 to 20 wt% (preferably, 1 to 15 wt%; more preferably, 2 to 12 wt%; most preferably, 5 to 10 wt%), based on weight of the first stage polymer, of structural units comprising a pendant absorbing group selected from the group consisting of a phosphoms acid group, phosphorus acid full-ester group and mixtures thereof; wherein the first stage polymer has a glass transition temperature in the range of -60 °C to 35 °C; and (b) 70 to 99 wt% (preferably, 75 to 96 wt%; more preferably,

80 to 95 wt%; most preferably, 85 to 92.5 wt%), based on weight of the multistage polymer, of a second stage polymer having a glass transition temperature in the range of 40 to 100 °C, wherein the second stage polymer is substantially free of pendant absorbing groups selected from phosphorus acid groups and phosphoms acid full-ester groups; wherein the second stage polymer incompletely encapsulates the first stage polymer (preferably, wherein the multistage polymer is acorn shaped).

[0017] Preferably, the multistage polymer of the present invention has a number average particle size of 5 to 90 nm as measured using a Brookhaven BI-90 photon correlation spectrometer. More preferably, the multistage polymer of the present invention has a number average particle size of 10 to 80 nm as measured using a Brookhaven BI-90 photon correlation spectrometer. Still more preferably, the multistage polymer of the present invention has a number average particle size of 15 to 35 nm as measured using a Brookhaven BI-90 photon correlation spectrometer. Most preferably, the multistage polymer of the present invention has a number average particle size of 20 to 30 nm as measured using a Brookhaven BI-90 photon correlation spectrometer. [0018] Preferably, the multistage polymer of the present invention comprises 1 to 30 wt% (preferably, 4 to 25 wt%; more preferably, 5 to 20 wt%; most preferably, 7.5 to 15 wt%), based on weight of the multistage polymer, of a first stage polymer; wherein the first stage polymer has a glass transition temperature, T _g , in the range of -60 °C to 35 °C. More preferably, the multistage polymer of the present invention comprises 1 to 30 wt% (preferably, 4 to 25 wt%; more preferably, 5 to 20 wt%; most preferably, 7.5 to 15 wt%), based on weight of the multistage polymer, of a first stage polymer; wherein the first stage polymer has a glass transition temperature, T _g , in the range of -40 °C to 35 °C (preferably, - 40 °C to 30 °C; more preferably; -40 °C to 25 °C; most preferably, -40 °C to 20 °C). Most preferably, the multistage polymer of the present invention comprises 1 to 30 wt% (preferably, 4 to 25 wt%; more preferably, 5 to 20 wt%; most preferably, 7.5 to 15 wt%), based on weight of the multistage polymer, of a first stage polymer; wherein the first stage polymer has a glass transition temperature, T _g , in the range of -25 °C to 35 °C (preferably, - 25 °C to 30 °C; more preferably; -25 °C to 25 °C; most preferably, -25 °C to 20 °C).

[0019] Preferably, the first stage polymer comprises 59.9 to 99.8 wt% (preferably, 84.5 to

98.5 wt%; more preferably, 87.25 to 97.25 wt%; most preferably, 88 to 93 wt%), based on weight of the first stage polymer, of structural units of a monoethylenically unsaturated first stage monomer. More preferably, the first stage polymer comprises 59.9 to 99.8 wt% (preferably, 84.5 to 98.5 wt%; more preferably, 87.25 to 97.25 wt%; most preferably, 88 to 93 wt%), based on weight of the first stage polymer, of structural units of a monoethylenically unsaturated first stage monomer; wherein the structural units of the monoethylenically unsaturated first stage monomer are selected from the group consisting of structural units of monoethylenically unsaturated first stage non-ionic monomer, structural units of monoethylenically unsaturated first stage carboxylic acid monomer and mixtures thereof. Most preferably, the first stage polymer comprises 59.9 to 99.8 wt% (preferably,

84.5 to 98.5 wt%; more preferably, 87.25 to 97.25 wt%; most preferably, 88 to 93 wt%), based on weight of the first stage polymer, of structural units of a monoethylenically unsaturated first stage monomer; wherein the structural units of the monoethylenically unsaturated first stage monomer are a mixture of structural units of monoethylenically unsaturated first stage non-ionic monomer and structural units of monoethylenically unsaturated first stage carboxylic acid monomer.

[0020] Preferably, the structural units of monoethylenically unsaturated first stage non-ionic monomer are selected from the group consisting of styrene; butadiene; a-methyl styrene; vinyl toluene; vinyl naphthalene; ethylene; propylene; vinyl acetate; vinyl versatate; vinyl chloride; vinylidene chloride; acrylonitrile; methacrylonitrile; (meth)acrylamide; C ₁ -C ₄₀ alkyl esters of (meth)aerylic acid (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate); other (meth) acrylates (e.g., isobomyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-bromoethyl (meth)acrylate); alkoxyalkyl (meth)acrylate (e.g., ethoxyethyl (meth)acrylate); mono-, di-, trialkyl esters of ethylenically unsaturated di- and tricarboxylic acids and anhydrides (e.g., ethyl maleate, dimethyl fumarate, and ethyl methyl itaconate) and mixtures thereof. More preferably, the structural units of monoethylenically unsaturated first stage non-ionic monomer are selected from the group consisting of styrene, Ci-22 alkyl (meth)acrylate monomers and mixtures thereof. Still more preferably, the structural units of monoethylenically unsaturated first stage non-ionic monomer are selected from the group consisting of styrene, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclo-hexyl (meth)aerylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, isodecyl (meth)acrylate, behenyl (meth)acrylate, cetyl-eicosyl (meth)acrylate and mixtures thereof.

Yet more preferably, the structural units of monoethylenically unsaturated first stage non ionic monomer are selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate and mixtures thereof. Most preferably, the structural units of monoethylenically unsaturated first stage non-ionic monomer are selected from the group consisting of butyl (meth)acrylate, methyl (meth)acrylate and mixtures thereof.

[0021] Preferably, the structural units of monoethylenically unsaturated first stage carboxylic acid monomer are selected from the group consisting of (meth)acrylic acid, (meth)acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid, maleic anhydride, fumaric acid, cro tonic acid, citraconic acid, maleic anhydride, monomethyl maleate, monomethyl fumarate, monomethyl itaconate, derivatives thereof (e.g., corresponding anhydrides, amides and esters) and mixtures thereof. More preferably, the structural units of monoethylenically unsaturated first stage carboxylic acid monomer are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid and mixtures thereof. Still more preferably, the structural units of monoethylenically unsaturated first stage carboxylic acid monomer are selected from the group consisting of at least one of acrylic acid and methacrylic acid. Most preferably, the structural units of monoethylenically unsaturated first stage carboxylic acid monomer are selected from the group consisting of, at least one of acrylic acid and methacrylic acid; wherein 75 to 100 mol% (preferably, 85 to 100 mol%; more preferably, 95 to 100 mol%; still more preferably, ³ 99 mol%; most preferably, 100 mol%) of the monoethylenically unsaturated first stage carboxylic acid monomer is methacrylic acid.

[0022] Preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of a mul tiethy lenical ly unsaturated first stage monomer; wherein the structural units of multiethylenically unsaturated first stage monomer are selected from the group consisting of multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule. More preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of the multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule is selected from the group consisting of divinylaromatic compounds, di-(meth)acrylate esters, tri-(meth)acrylate esters, tetra-(methacrylate)esters , di-allyl ethers, tri-allyl ethers, tetra-allyl ethers, di-allyl esters, tri-allyl esters, tetra-allyl esters, allyl (meth)acrylate and mixtures thereof. Still more preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of the multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule is selected from the group consisting of divinylbenzene (DVB); divinyltoluene, trivinylbenzene; divinyl naphthalene; trimethylolpropane diallyl ether; tetra-allyl pentaerythritol; triallyl pentaerythritol; diallyl pentaerythritol; dially phthalate; diallyl maleate; triallyl cyanurate; Bisphenol A diallyl ether; allyl sucroses; methylene bisacrylamide; trimethylolpropane tri(meth)acrylate; allyl methacrylate (ALMA); ethylene glycol di(meth)acrylate; hexane- 1,6-diol di(meth)acrylate; butylene glycol di(meth)acrylate; tripropylene glycol di(meth)acrylate; diethylene glycol di(meth)acrylate; ethylene glycol di(meth)acrylate; 1,3-butylene glycol di(meth)acrylate; polyalkylene glycol di(meth)acrylate and mixtures thereof. Yet more preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of the multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule is selected from the group consisting of DVB, ALMA, ethylene glycol dimethacrylate (EGDMA), hexane- 1,6-diol di acrylate (HDDA) and butylene glycol dimethacrylate (BGDMA). Yet still more preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of the multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule include ALMA. Most preferably, the first stage polymer comprises 0.1 to 40 wt% (preferably, 0.5 to 10 wt%; more preferably, 0.75 to 5 wt%; most preferably, 1 to 2 wt%), based on weight of the first stage polymer, of structural units of the multiethylenically unsaturated first stage monomer having at least two ethylenically unsaturated groups per molecule is ALMA.

[0023] Preferably, the first stage polymer comprises 0.1 to 20 wt% (preferably, 1 to 15 wt%; more preferably, 2 to 12 wt%; most preferably, 5 to 10 wt%), based on weight of the first stage polymer, of structural units comprising a pendant absorbing group selected from the group consisting of a phosphoms acid group, phosphorus acid full-ester group and mixtures thereof. More preferably, the first stage polymer comprises 0.1 to 20 wt% (preferably, 1 to 15 wt%; more preferably, 2 to 12 wt%; most preferably, 5 to 10 wt%), based on weight of the first stage polymer, of structural units comprising a pendant absorbing group; wherein the structural units comprising pendant absorbing groups include phosphoms acid full-ester groups. Most preferably, the first stage polymer comprises 0.1 to 20 wt% (preferably, 1 to 15 wt%; more preferably, 2 to 12 wt%; most preferably, 5 to 10 wt%), based on weight of the first stage polymer, of structural units comprising a pendant absorbing group; wherein the structural units comprising pendant absorbing groups are phosphoms acid full-ester groups. [0024] The term “phosphoms acid group” as used herein and in the appended claims refers to a phosphoms oxo acid having a POH moiety in which the hydrogen atom is ionizable or to the salt of the phosphoms oxo acid. In its salt or basic form, the phosphoms acid group has a metal ion or an ammonium ion replacing at least one acid proton. Included in the definition of the term “phosphoms acid group” are partial esters of phosphoms oxo acids. The partial esters of phosphoms oxo acids, as referred to “partial esters of phosphoms acid” contain at least one POH moiety and a phosphoms ester moiety represented by POR, where R is a group containing a carbon atom bonded to the oxygen atom attached to the phosphoms atom. Examples of phosphoms acid groups include groups formed from phosphinic acid, phosphonic acid, phosphoric acid, pyrophosphinic acid, pyrophosphoric acid, partial esters thereof, and salts thereof. [0025] Preferably, the phosphorus acid groups are incorporated into the first stage polymer by polymerization of a phosphorus acid group monomer. The phosphorus acid group monomer contains at least one ethylenic unsaturation and a phosphorus acid group. The phosphorus acid group monomer is alternatively in the acid form or as a salt of the phosphorus acid group. Examples of phosphorus acid group monomers include: wherein each R group is an organic group containing an acryloxy, methacryloxy or a vinyl group; and each R' and R" group is independently selected from H and a second organic group. The second organic group is alternatively saturated or unsaturated.

[0026] Preferred phosphorus acid group monomers include dihydrogen phosphate-functional monomers such as dihydrogen phosphate esters of an alcohol wherein the alcohol also contains a polymerizable vinyl or olefinic group (e.g., allyl phosphate, mono- or diphosphate of bis(hydroxy-methyl) fumarate and itaconate); derivatives of (meth)acrylic acid esters (e.g., 2-hydroxyethyl (meth)acrylate and 3 -hydroxypropyl (meth)acrylates); phosphonate functional monomers (e.g., vinyl phosphonic acid, allyl phosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, ot-phosphonostyrene and 2-methylacrylamido-2-methylpropanephosphonic acid); 1,2-ethylenically unsaturated (hydroxy )phosphinylalkyl (meth)acrylate monomers (e.g., (hydroxy )phosphinylmethyl methacrylate) and mixtures thereof. More preferred phosphorus acid monomers include dihydrogen phosphate monomers such as 2-phosphoethyl (meth)acrylate, 2-phosphopropyl (meth)acrylate, 3-phosphopropyl (meth)acrylate, 3 -phospho-2-hydroxypropyl (meth)acrylate and mixtures thereof.

[0027] The term “phosphorus acid full-ester group” as used herein and in the appended claims refers to a phosphorus oxo acid having one or more phosphorus acid moieties, but not containing a POH moiety. Examples of phosphorus acid full-ester groups include full esters of phosphinic acid, phosphonic acid, phosphoric acid, pyrophosphinic acid, and pyrophosphoric acid. [0028] Preferably, the phosphorus acid full-ester groups are incorporated into the first stage polymer by polymerization of a phosphorus acid full-ester group monomer. Preferred phosphorus acid full-ester group monomers include trivinyl phosphate; (2-inethacryloloxy)ethyl-diethyl-phosphate; di(4-methacryloloxy)butyl-methyl-phosphate; vinyl phosphonic acid, diethyl ester; and glycerol monoacrylate, di(diethylphosphate)ester. [0029] Preferably, the first stage polymer has a weight average molecular weight of ³ 100,000 Daltons. More preferably, the first stage polymer has a weight average molecular weight of ³ 200,000 Daltons. Most preferably, the first stage polymer has a weight average molecular weight of ³ 250,000 Daltons. Preferably, the first stage polymer has a weight average molecular weight of < 5,000,000. The weight average molecular weight of the first polymer is determined by preparing the polymer in the absence of the second polymer and measuring the weight average molecular weight using gel permeation chromatography. [0030] Preferably, the multistage polymer of the present invention comprises 70 to 99 wt% (preferably, 75 to 96 wt%; more preferably, 80 to 95 wt%; most preferably, 85 to 92.5 wt%), based on weight of the multistage polymer, of a second stage polymer having a glass transition temperature in the range of 40 to 100 °C (preferably, 50 to 90 °C; more preferably, 60 to 80 °C; most preferably, 65 to 75 °C ), wherein the second stage polymer is substantially free of pendant absorbing groups selected from phosphorus acid groups and phosphorus acid full-ester groups. The term “substantially free” as used herein and in the appended claims means the second stage polymer includes less than 5 wt% (preferably, < 2 wt%; more preferably, < 1 wt%; still more preferably, < 0.1 wt%; yet more preferably, < 0.01 wt%; most preferably, less than the detectable limit), based on weight of the second stage polymer, of phosphorus acid groups and phosphorus acid full-ester groups.

[0031] Preferably, the second stage polymer comprises structural units of an ethylenically unsaturated second stage monomer. More preferably, the second stage polymer comprises structural units of an ethylenically unsaturated second stage monomer; wherein the structural units of ethylenically unsaturated second stage monomer is selected from the group consisting of stmctural units of monoethylenically unsaturated second stage non-ionic monomer, stmctural units of monoethylenically unsaturated second stage carboxylic acid monomer and mixtures thereof. Most preferably, the second stage polymer comprises stmctural units of an ethylenically unsaturated second stage monomer; wherein the stmctural units of ethylenically unsaturated second stage monomer is a mixture of structural units of monoethylenically unsaturated second stage non-ionic monomer and stmctural units of monoethylenically unsaturated second stage carboxylic acid monomer. [0032] Preferably, the structural units of monoethylenically unsaturated second stage non- ionic monomer are selected from the group consisting of styrene; butadiene; oc-methyl styrene; vinyl toluene; vinyl naphthalene; ethylene; propylene; vinyl acetate; vinyl versatate; vinyl chloride; vinylidene chloride; acrylonitrile; methacrylonitrile; (meth)acrylamide; C ₁ -C ₄₀ alkyl esters of (meth)acrylic acid (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate); other (meth) acrylates (e.g., isobomyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-bromoethyl (meth)acrylate); alkoxyalkyl (meth)acrylate (e.g., ethoxyethyl (meth)acrylate); mono-, di-, trialkyl esters of ethylenically unsaturated di- and tricarboxylic acids and anhydrides (e.g., ethyl maleate, dimethyl fumarate, and ethyl methyl itaconate) and mixtures thereof. More preferably, the structural units of monoethylenically unsaturated second stage non-ionic monomer are selected from the group consisting of styrene, Ci-22 alkyl (meth)acrylate monomers and mixtures thereof. Still more preferably, the structural units of monoethylenically unsaturated second stage non-ionic monomer are selected from the group consisting of styrene, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclo-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, isodecyl (meth)acrylate, behenyl (meth)acrylate, cetyl-eicosyl (meth)acrylate and mixtures thereof.

Yet more preferably, the structural units of monoethylenically unsaturated second stage non ionic monomer are selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate and mixtures thereof. Most preferably, the structural units of monoethylenically unsaturated second stage non-ionic monomer are selected from the group consisting of butyl (meth)acrylate, methyl (meth)acrylate and mixtures thereof.

[0033] Preferably, the structural units of monoethylenically unsaturated second stage carboxylic acid monomer are selected from the group consisting of (meth)acrylic acid, (meth)acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid, maleic anhydride, fumaric acid, cro tonic acid, citraconic acid, maleic anhydride, monomethyl maleate, monomethyl fumarate, monomethyl itaconate, derivatives thereof (e.g., corresponding anhydrides, amides and esters) and mixtures thereof. More preferably, the structural units of monoethylenically unsaturated second stage carboxylic acid monomer are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid and mixtures thereof. Still more preferably, the structural units of monoethylenically unsaturated second stage carboxylic acid monomer are selected from the group consisting of at least one of acrylic acid and methacrylic acid. Most preferably, the structural units of monoethylenically unsaturated second stage carboxylic acid monomer are selected from the group consisting of, at least one of acrylic acid and methacrylic acid; wherein 75 to 100 mol% (preferably, 85 to 100 mol%; more preferably, 95 to 100 mol%; still more preferably, ³ 99 mol%; most preferably, 100 mol%) of the monoethylenically unsaturated second stage carboxylic acid monomer is methacrylic acid.

[0034] Preferably, the second stage polymer has a weight average molecular weight of 10,000 to 5,000,000 Daltons. More preferably, the second stage polymer has a weight average molecular weigh of 50,000 to 2,000,000 Daltons. Most preferably, the second stage polymer has a weight average molecular weight of 100,000 to 1,000,000 Daltons. The weight average molecular weight of the second polymer is determined by preparing the polymer in the absence of the first polymer and measuring the weight average molecular weight using gel permeation chromatography.

[0035] Methods for making the multistage polymer of the present invention are well know. Preferably, the multistage polymer of the present invention is prepared via a process where the seed is formed in situ.

[0036] While having a plurality of potential uses (including use in coating formulations such as paints), the multistage polymer particles are preferably designed for use in combination with inorganic materials to form composite organic-inorganic particles for use in personal care formulations. More preferably, the multistage polymer particles are designed for use in combination with inorganic materials to form composite organic-inorganic particles for use in personal care formulations selected from color cosmetics and sun care formulations.

[0037] Preferred inorganic materials for use in combination with the multistage polymer of the present invention include pigment particles. Pigment particles may include for example, zinc oxide, antimony oxide, zirconium oxide, chromium oxide, iron oxide, lead oxide, zinc sulfide, lithopone, and forms of titanium dioxide (e.g., anatase and rutile). Preferably, the pigment particles are selected from iron oxide, zinc oxide, titanium dioxide and mixtures thereof. More preferably, the pigment particles are selected from zinc oxide, titanium dioxide and mixtures thereof. Most preferably, the pigment particles are titanium dioxide.

[0038] Preferably the inorganic materials have a number average particle size of < 100 ran as measured using a Brookhaven BI-90 photon correlation spectrometer. More preferably, the inorganic materials have a number average particle size of 5 to 75 nm as measured using a Brookhaven BI-90 photon correlation spectrometer. Most preferably, the inorganic materials have a number average particle size of 50 to 70 nm as measured using a Brookhaven BI-90 photon correlation spectrometer.

[0039] Some embodiments of the present invention will now be described in detail in the following Examples.

[0040] The abbreviations listed in TABLE 1 are used in the examples.

Preparation of aqueous dispersions containing multistage polymers

[0041] Aqueous dispersions containing multistage polymers were prepared in a 3 liter, four necked round bottom flask equipped with a paddle stirrer, a thermometer, a nitrogen inlet and a reflux condenser connected to a mineral oil bubbler outlet.

[0042] The PEM used is the preparation of the examples was unpurified and contained 52.2 wt% phosphoethyl methacrylate monomer, 33.2 wt% phosphodi(ethyl methacrylate) and 14.5 wt% phosphoric acid. The phosphodi(ethyl methacrylate) is a multiethylenically unsaturated monomer. The ammonium hydroxide was 28 wt% active.

Example SI: Multistage Polymer Synthesis

[0043] The kettle was charged with deionized water (900 g) and a fatty alcohol ether sulfate, sodium salt (17.32 g; DISPONIL FES-32 available from BASF). The kettle contents were then set to stir with a nitrogen flow and heated to 83-85 °C. To a first plastic lined vessel was added, and mixed with overhead stirring, deionized water (55.56 g); PEM (7.56 g) and a fatty alcohol polyglycol ether sulfate, sodium salt (9.44 g; DISPONIL FES-993 available from BASF). To the stirring mixture in the first plastic lined vessel BA (54.78 g); MMA (28.8 g); ALMA (1.42 g) and MAA (1.9 g) were charged and allowed to form a first smooth, stable monomer emulsion (“ME1”). To a second plastic lined vessel was added, and mixed with overhead stirring, deionized water (255.0 g) and DISPONIL FES-32 (28.78 g). To the stirring mixture in the second plastic lined vessel BA (119.85 g); MMA (728.45 g) and MAA (1.7 g) were added and allowed to form a second smooth, stable monomer emulsion (“ME2”).

[0044] An initial catalyst charge of ammonium persulfate (3.78 g) in deionized water (25.0 g) was prepared. An MEl rinse of deionized water (13.89 g) was prepared. An ME2 rinse of deionized water (25.0 g) was prepared. A co-feed catalyst charge of ammonium persulfate (0.94 g) in deionized water (40.86 g) was prepared. A co-feed neutralizer solution of 29% ammonium hydroxide (3.50 g) in deionized water (19.44 g) was prepared and set aside.

[0045] When the kettle contents reached temperature, the initial catalyst charge was added to the kettle and MEl was fed subsurface into the kettle over a total of 30 minutes. The flow of co-feed catalyst solution to the kettle was initiated simultaneously with the MEl feed at a rate of 0.38 g/min. for a period of 110 minutes. At the completion of the MEl feed, the MEl rinse of deionized water (13.89 g) was added as a rinse and the co-feed catalyst solution was paused. The kettle contents were held for 10 minutes at 83-85 °C. Following the ten minute hold, the co-feed catalyst solution feed was restarted and the ME2 was fed to the kettle subsurface over a period of 80 minutes. After 20 minutes of the ME2 feed, the co-feed neutralizer solution was fed into the kettle over 60 minutes at a rate of 0.38 g/min. At the end of the ME2 feed, the kettle contents were held for 20 minutes at 83-85 °C.

[0046] During the hold, a chase promoter solution of 0.15% iron sulfate heptahydrate (5.0 g) was prepared. A chase activator solution of isoascorbic acid (0.84 g) dissolved in deionized water (15.0 g) was prepared. A chase catalyst solution of 31% hydrogen peroxide (1.7 g) in deionized water (15.0 g) was prepared.

[0047] Following the 20 minute hold, the kettle contents were allowed to cool. When the kettle contents reached 65 °C, the chase promoter solution was added as a shot to the kettle. The kettle contents were then cooled to 45 °C, while adding the chase activator solution and the chase catalyst solution separately by syringe over 30 minutes at a feed rate of 0.67 g/min. When cooled to room temperature, the kettle contents were filtered through a 100 mesh bag. The final product solids was 39.88 wt%, pH=3.44. Particle size by BI-90 was 71.7 nm.

Example S2: Multistage Polymer Synthesis

[0048] The kettle was charged with deionized water (1054 g) and a fatty alcohol ether sulfate, sodium salt (14.55 g; DISPONIL FES-32 available from BASF). The kettle contents were then set to stir with a nitrogen flow and heated to 83-85 °C. To a first plastic lined vessel was added, and mixed with overhead stirring, deionized water (34.44 g); PEM (4.68 g) and a fatty alcohol polyglycol ether sulfate, sodium salt (5.86 g; DISPONIL FES-993 available from BASF). To the stirring mixture in the first plastic lined vessel BA (33.96 g); MMA (17.86 g); ALMA (0.88 g) and MAA (1.18 g) were charged and allowed to form a first smooth, stable monomer emulsion (“ME1”). To a second plastic lined vessel was added, and mixed with overhead stirring, deionized water (158.1 g) and DISPONIL FES-32 (17.84 g).

To the stirring mixture in the second plastic lined vessel BA (74.31 g); MMA (451.64 g) and MAA (1.05 g) were added and allowed to form a second smooth, stable monomer emulsion (“ME2”).

[0049] An initial catalyst charge of ammonium persulfate (2.34 g) in deionized water (15.50 g) was prepared. An ME1 rinse of deionized water (8.61 g) was prepared. An ME2 rinse of deionized water (15.50 g) was prepared. A co-feed catalyst charge of ammonium persulfate (0.59 g) in deionized water (25.33 g) was prepared. A co-feed neutralizer solution of 29% ammonium hydroxide (2.17 g) in deionized water (12.06 g) was prepared and set aside.

[0050] When the kettle contents reached temperature, the initial catalyst charge was added to the kettle and ME1 was fed subsurface into the kettle over a total of 30 minutes. The flow of co-feed catalyst solution to the kettle was initiated simultaneously with the ME1 feed at a rate of 0.24 g/min. for a period of 110 minutes. At the completion of the ME1 feed, the ME1 rinse of deionized water (8.61 g) was added as a rinse and the co-feed catalyst solution was paused. The kettle contents were held for 10 minutes at 83-85 °C. Following the ten minute hold, the co-feed catalyst solution feed was restarted and the ME2 was fed to the kettle subsurface over a period of 80 minutes. After 20 minutes of the ME2 feed, the co-feed neutralizer solution was fed into the kettle over 60 minutes at a rate of 0.24 g/min. At the end of the ME2 feed, the kettle contents were held for 20 minutes at 83-85 °C.

[0051] During the hold, a chase promoter solution of 0.15% iron sulfate heptahydrate (3.10 g) was prepared. A chase activator solution of isoascorbic acid (0.52 g) dissolved in deionized water (9.30 g) was prepared. A chase catalyst solution of 31% hydrogen peroxide (1.05 g) in deionized water (9.30 g) was prepared.

[0052] Following the 20 minute hold, the kettle contents were allowed to cool. When the kettle contents reached 65 °C, the chase promoter solution was added as a shot to the kettle. The kettle contents were then cooled to 45 °C, while adding the chase activator solution and the chase catalyst solution separately by syringe over 30 minutes at a feed rate of 0.35 g/min. When cooled to room temperature, the kettle contents were filtered through a 100 mesh bag. The final product solids was 30.0 wt%, pH=3.18. Particle size by BI-90 was 54.9 nm. Example S3; Multistage Polymer Synthesis

[0053] Polymer S3 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 4.80 g. The final product solids was 30.05 wt%, pH=3.36. Particle size by Bl-90 was 66.3 nm.

Example S4: Multistage Polymer Synthesis

[0054] Polymer S4 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 1.95 g. The final product solids was 30.79 wt%, pH=3.35. Particle size by BI-90 was 89.1 nm.

Example S5: Multistage Polymer Synthesis

[0055] Polymer S5 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 4.00 g. The ME1 was prepared by adding deionized water (34.44 g), PEM (4.68 g); DISPONIL FES-993 (5.86 g) to the first plastic lined vessel with overhead stirring. To the stirring solution was then added BA (16.4 g); EA (12.01 g); MMA (0.88 g); ALMA (0.88 g) and MAA (1.17 g) with continued stirring to form the first smooth, stable monomer emulsion ME1. The final product solids was 29.82%, pH= 5.75. Particle size by BI-90 was 61.2 nm.

Example S6: Multistage Polymer Synthesis

[0056] Polymer S6 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 4.00 g. The MEl was prepared by adding deionized water (34.44 g), PEM (4.68 g); DISPONIL FES-993 (5.86 g) to the first plastic lined vessel with overhead stirring. To the stirring solution was then added EA (40.99 g); MMA (10.83 g); ALMA (0.88 g) and MAA (1.17 g) with continued stirring to form the first smooth, stable monomer emulsion MEl. The final product solids was 29.97%. Particle size by BI-90 was 57.8 nm.

Example S7: Multistage Polymer Synthesis

[0057] Polymer S7 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 3.90 g. The ME2 was prepared by adding deionized water (158.1 g) and DISPONIL FES-32 (17.84 g) to the first plastic lined vessel with overhead stirring. To the stirring solution was then added EHA (74.31 g); MMA (451.64 g); ALMA (0.88 g) and MAA (1.05 g) with continued stirring to form the second smooth, stable monomer emulsion ME2. The final product solids was 29.99%. Particle size by BI-90 was 69.6 nm.

Example S8: Multistage Polymer Synthesis

[0058] Polymer S8 was prepared using the same multistage polymer synthesis described in Example S2 with adjustment to the initial DISPONIL FES-22 added to the kettle being reduced to 1.95 g. The ME2 was prepared by adding deionized water (158.1 g) and DISPONIL FES-32 (17.84 g) to the first plastic lined vessel with overhead stirring. To the stirring solution was then added BMA (210.8 g); MMA (315.15 g); and MAA (1.05 g) with continued stirring to form the second smooth, stable monomer emulsion ME2. The final product solids was 29.88%. Particle size by BI-90 was 78.5 nm.

Formulation Examples G1 and G2: Generic Suncare Formulations

[0059] Generic suncare personal care formulations were prepared having the generic formulations according to Formulation Examples G1 and G2 noted in TABLE 3. The Phase A ingredients (except the xanthan gum) were added to a flask. The flask contents were then stirred at room temperature while adding the xanthan gum. Following addition of the xanthan gum, the flask contents were stirred for five minutes before heating the flask contents to 75 °C with continued stirring. The Phase B ingredients were combined in a separate container while being heated at 75 °C with mixing until dissolved. The Phase B ingredients were then added to the flask contents with mixing until uniform. The flask contents were then removed from the heating source and cooled. When the flask contents cooled below 50 °C, the Phase C ingredient was added to the flask contents with mixing until uniform. When the flask contents cooled to below 40 °C, the Phase D ingredient was added to the flask contents with continued mixing until the flask contents reached ambient room temperature. The flask contents were then pH adjusted to a pH of 8, as necessary.

Comparative Examples C1-C3 and Examples 1-9: Suncare Formulations

[0060] The suncare formulations of Comparative Examples C1-C3 and Examples 1-9 were prepared using Generic Formulations CGF1-CGF3 and GF1-GF3 and the Polymer (if any) as noted in TABLE 4 along with the calculated SPF for each formulation.