CA2013761C - Antidandruff shampoo compositions - Google Patents

Abstract

ANTIDANDRUFF SHAMPOO COMPOSITIONS

ABSTRACT
Antidandruff shampoos comprising a surfactant, platelet zinc pyridinethione active of specific particle size, a suspending agent, water, and a synergizer for the active. Said compositions have superior efficacy when compared with antidandruff shampoos known in the art.

Description

-ANTIDANDRUFF SHAMPOO COMPOSITIONS
Carollne ~lnyard Cardln Joyce Ingram Davls Judl Lynn Hart Diane Grob Schmldt ~E~NICAL FLEL~
The present 1nvent~on relates to antidandruff shampoos.
These shampoos exhlblt excellent ant1ldandruff ~ctlv1ty.
~ACKGROUND OF ~HE INVENT~Q~
Ant1dandruff shampoos are well known in the ~rt and rely upon various actives for thelr antldaildruf~ effectlveness. Such compositions are not only deslgned to relleve the dandruff condl-tion, but also to effeet~vely clean the ha~r.
U.S. Patent 3,9I7,8I7, Vanlerberghe et al., 1ssued Nove~ber 5, I975, dlscloses a ~hampoo compositlon compr~s~ng a plperazine based cation1c polymer actlve, IO% sodlum ~lkyl sulfate, ~X lauryl monoethanolamide and 3~ glycol distearate. U.S. Patent 4,013,787, Vanlerberghe et ~l., 1ssued March 22, 1977, d~scloses sl~llar compositions.
Pyridineth~one salts are known for use as dandruff control actives. Speclflcally, I-hydroxypyrldlnethlone salts have been taught as antidandruff actlves ~n lot)on form shampoos. Included ~n thls group 1s 2-z1nc pyrith~one (ZP7) ~s dlsclosed ~n U.S.
Patent 2,809,97I, ~ernste~n, issued October l5, 1957 ; U.S. Patent 3,236,733, Karsten, lssu~d February 22~ 196S; U.S. Patent 3,7~3,916, Parran, ~ssued August 2I, 1973; Japanes~ Publlshed Appl~cat10n 608IO, publ~shed May l9, I977 (L10n Fat ~ 011); U.S.
Patent 4,323,683, ~olich et al., 1~sued Apr~l 6, 1982; U.5. Patent 4,345,080, ~ollch, ~ssued August 17, I982; U.S. ~,379,753, Bolich, ~ssued Aprll 12, 1983; U.S. Patent ~,470,982, ~l~nkler, issued September 11, 1984; and European Publ1shed Patent Appllcatlon : No. 2.5,388, publ~shed October 5, I988.
In the present inventlon lt has been surpr~slngly found that when a pyridln2th~0ne metal salt ~n platelet form, w~th a spec~-f~ed part~cle s~ze, ~s combined w1th ~ny of ~ group of spec~flc - 2 ~ 7~
synergizers ~n a shampoo matrix, an unexpected substant~al lm-pro~ement in antidandruff efficacy is realized. Suoh compositlons are stable, safe and effective in cleaning the ha~r while treating the scalp for dandruff.
SUMMARY OF THE~ T~Q~
The present inventlon relates to shampoo compos~tlons compris~ng:
(a) from about 5% to about 7~X of a synthetic surfactant;
(b) from about 0.3% to about 2% of pyrid~nethione metal salt in platelet particle form having a mean part~ele s~ze of from about 2 microns to about 15 microns;
(c) from about 0.5% to about 5X of a syneryizer selected from the group consisting of polyethylene glycols containing from about 6 to about 22 ethylene oxlde un~ts, polypropylene glysols contain~ng from about 6 to about 22 propylene oxide units, polyoxa~er block polymers, polyethylene oxide fatty glycerides, poly-ethylenimines containing from about 6 to about 22 i~lne groups, polyethoxylated polyethylenimines, polyethylene oxida carbohydrates, ethoxylated nonylphenols, ethoxylated alcohols, and ~ixtures thereof tprePerred synerg~zers include the polyethylene glycols, particularly PEG-12);
(d) from about 0.5% to about 6X of a suspending agent; and (e) the remainder water.
These antidandruff shampoos are effectivs in ol~ansing the halr, as well as effect~Yely treatlng dandruff. These compo-s~tions may also 1nclude additional antidandruff actiYes and/or silicone polymers to condition the hair w~thout interrupt~ng the treatment of said dandruff. The lotlon ~orM ls particularly preferred for the shampoos.
All ratios, percentages an~ parts giYen herein are ~by weight~ unless otherw~se specif1ed.

, ~3~
, QETAI~ED DESCRIPTION OF ~HE INYENJIQ~
The essent~al components of the present ~nvent10n as wel7 as optional components, are set forth in the follow~ng paragraphs.
Surfactant 5An essential component of the present compos~t10ns ~s a synthet~c surfactant. The surfactant, wh~ch ~ay be selected frs~
any of a wide variety of synthet~c an~on~c~ amphoter~c, zwitterionic and nonionic surfactants typicall~ used in shampoos, is present at a le~el of from about 5X to about 70X, preferably 10from about 10% to about 30%7 most preferably from about 1~X to about 22%, of the composition.
Synthetic an~on~c surfactants can be exe~plif~ed by the alkali metal salts of organ~c sulfuric react~on products hav~ng ln their molecular structure an alkyl radlcal conta~n~ng from 8-22 15carbon atoms and a sulfonlc acid or sulfuric acld ester radical (included ~n the term alkyl 1s the alkyl portion of higher acyl radtcals). Preferred are the sodium, ammon~um, potassiu~ or triethanolamine al kyl sul fates, espec~ al ly those obtai ned by sulfating the higher alcohols (C~-Cl~ carbon atoms), sodlu~
20coconut oil fatty acids monoglyceride sulfat~s and sulfonates;
sodium or potass~um salts of sulfur1c acid esters of the reaction product of 1 mole of a h~gher fatty alcohol (e.g., tallow cr coconut o~l alcohols) and 1 to 12 moles of ethyl~ne oxide; sod~ua or potass1um salts of alkyl phenol ethylene oxlde ether sulfat~
25with 1 to 10 units of ethylene oxide per molecule and ~n wh~ch the alkyl radicals contain from 8 to 12 carbon atoms, sod~um alkyl glyccryl ether sulfonates; th~ reaction product of fatty ac~ds hav~ng from 10 to 22 carbon atoms ester~f~d w~th lseth~onlc acid and neutralized wlth sodium hydrox~de; water soluble salts o~
30condensation products of fatty acids with sarcoslne; and others known in the art.
~witterionic surfactants can be exemplified by those wh~ch can be broadly described as der~vat~ves of al1phat~c quaternarr ammonium, phosphon~um, and sulfonium compounds, in wh kh the 35aliphatic radkals can be stra~ght cha~n or branched, and wher~n ~ ~37~

one of the al~phatlc substituents conta1ns from about 8 to 18 carbo~ atoms and one contains an anionlc wat~r-solubiliz~ng group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. A
general formula for these compounds ls:
(R3~ %
R2 - Y~-)CH2 - R4 - Z( ~
wherein R2 contains an alkyl, alkenyl, or hydroxyalkyl radtcal of from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxid~ moieties and from 0 to I ~lyceryl molety; Y 1s selected fro~
the group consisting of nitrogen. phosphorus, and sulfur atoms; R3 is an alkyl or monohydroxyalkyl group conta~ning 1 to about 3 carbon atoms, x ~s 1 when Y is a sulfur atom and 2 when Y ~s a nitrogen or phosphorus 2tom; R~ ~s an alkylene or hydroxyalkylene of from 1 to about 4 carbon atoms; and Z ~s ~ rad~cal selected from the group conslsting of carboxylate, sulfonat~, sulfate, phosphonate, and phosphate ~roups.
Examples ~nclude:
4-~N,N-d~(2-hydroxyethyl)-N-octadecylamnon~o]-butdne-l-carboxy-late;

5-~S-3-hydroxypropyl-S-he%adecylsulfonlo3-3-hydroxypentane-1-sulfate;
3-[P,P-di~thyl-P-3,6,9-trioxatetradexocylphosphonio3-2-hydroxy-propane-l-phosphate;
3-[N,N-d~propyl-N-3-dodecoxy-2-hydroxYpropylammon~o]-propane-l-phosphonate;
3-(N,N-d~m~thyl-N-hexadecylammonio)pro~an~-l-sulfonate;
3-(N,N-d~methyl-N-hexadecylam~onio)-2-hydroxypropane-1-sulfonate;
4-[N,N-d~(2-hydro%y~thyl)-N-(2-hydroxydodecyl)an~non~o~-butane-1-carboxylate;
3-[S-ethyl-S-(3-dodecoxy-2-hydroxypropyl)sulfonlo]-propane-1-phosphate;
3-[P,P-dimethyl-P-~odecylphosphonio]-propane-l-phssphonate; and 5-[N,N-di(3-hydroxypropyl)-N-hexadecylammonio]-2-hydroxypentane-l-sulfate.

- -~:
.

Other zwitterionics, such as betaines, are also useful in the present invention. Exa~ples of betaines us~ful herein lnclude the high alkyl betaines such as coco dimethyl carboxymeth~l beta~ne, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl alpha-- 5 carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine~ lauryl bis-(2-hydroxyethyl) carboxymethyl betaine, stearyl bis-~2-hydroxypropyl) carboxymethyl betaine, oleyl d~methyl gamma-carboxypropyl betaine, and lauryl bis-(2-hydroxypropyl) alpha-carboxyethyl betaine~ The sulfobetaines may be represented by, for example, coco dimethyl sulfopropyl beta~ne, stearyl dimethyl sulfopropyl betaine, lauryl d~methyl sulfoethyl betaine, and lauryl bis-(2-hydroxyethyl) sulfopropyl betaine. Am~do betain~s and amidosulfobetaines, wherein the RCONH(CH2)3 radlcal is at-- tached to the nitrogen atom of the betalne, are also useful in this ~nvent~on.
Examples of amphoteric surfactants which can be used ln the compos~t~ons of the present invention are those which can be - broadly described as derivatives of allphat k secondary and tertiary amines in wh1ch the al~phat~c radical can be straight chain or branched and wherein one of the al~phatic substituents contains from about 8 to about 18 carbon atoms and one contalns an anionic water solub~lizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonat~. Examples o~ compounds falling with~n th~s deftnitlon are sodium 3-dodecyl-aminopropionate, sodium 3-dodecyla~inopropane sulfonate, N-alkyltaurines such as the o~e prepared by reacting dodecyla~ne ~ith sodium isethionate aocord~ng to the teaching of U.S. Patent 2,658,077, N-higher ~lkyl aspartic aclds such as those produced accord~ng to the teaching of U.S. Patent 2j438,091, and the products sold under the trade name ~ 30 ~Miranola and described in U.S. Pa~ent 2,528,378.
Non~on~c surfactants, wh kh are preferably used in combina-tion with an anionic, amphoteric or zwitterionic surfactant, can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydroph~lic in nature) with an organic * Trademark ~3'~

hydrophobic compound, which may be aliphatic or alkyl aromatic ~n nature. E~amples of preferred classes of nonionic surfactants are:
1. The polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols hav~ng an alkyl group containing from about 6 to 12 carbon atoms ~n either a straight chain or branched chain conflguration, w~th ethylene oxide, the said ethylene oxlde being present ~n amounts equal to 10 to 60 moles of ethyléne oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be der~ved from poly-merized propylene, diisobutylene, octane, or nonane, for example.
2. Those deriv~d from th~ condensat~on of ethylene ox1de with the product resulting from the react~on of propylene oxide and ethylene diamine products which may be var~ed ~n composition depending upon the balance between the hydrophob~c and hydrophil~c elements wh~ch is desired. For example, compounds containing from about 40% to about 80% polyoxyethylen~ by weight and having a molecular weight of from abou~ 5,000 to abo~lt 11,000 resulting from the reaction of ethylene oxide groups w~th a hydrophobic bas~
constituted of the reaction product of ethylene diam~ne and excess propylene oxide, said base having a molecular weight of the order of 2,500 to ~,000, are satisfactory.
3. The condensation product o~ al~phatic alcohols having from 8 to 18 carbon atoms, in either straight cha~n or branched chain conf~gurat~on, with ethylene ox~de, @.9., a coconut alcohol ethylene oxlde condensate having from 10 to 30 moles o~ ethylene oxide per mole of coconut alcohol, the coconut alcohol fraction having from 10 to 14 carbon atoms.
4. Long chain tertiary amine ox~d~s corresponding to the following gen~ral formula:
RlR2R3N ~ O
wherein Rl contains an alkyl, alkenyl or monohydroxyalkyl radical of ~rom about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide mo~eties, and from O to 1 glyceryl mo~ety, and R2 and R3 contain from 1 ts about 3 carbon atQms and ~rom 0 to about 20~3~G~

1 hydroxy group, e.g., methyl, ~thyl, propyl, hydroxyethyl, or hydroxypropyl radicals. The arrow in the formula is a conven-tional representat1On of a sem~polar bond. xamples of am~ne oxides suitable for use in th~s lnvention lnclude dimethyldodecyl-amine oxide, oleyldi(2-hydroxyethyl) amine ox~det dimcthyloctyl-amine oxide, dimethyldecylamine oxide, d~methyltetradecylamlne oxide, 3,6,9-trioxaheptadecyldiethylamine oxide, d~(2-hydroxy-ethyl)-tetradecylamine oxide, 2-dodecoxyethyld~methylamine ox1de, 3-dodecoxy-2-hydroxypropyldi(3-hydroxypropylJam~ne oxide, dl-methylhexadecylamine oxide.
5. Long chain tertiary phosphine oxides corresponding to the following general formula:
RR'Rnl? -~ o wherein R contains an alkyl, alkenyl or monohydroxyalkyl rad~cal ranging from 8 to 18 carbon atom~ in cha~n length, from 0 to about 10 ethylene oxide moieties and from O to 1 glyceryl moiety, and R' and R~ are each alkyl or monohydroxyalkyl groups conta~ning fro~ 1 to 3 carbon atoms. The arrow 1n the formula ls a convent~onal representation of a s2mipolar bond. Examples of suitable phss-ph~ne oxides are: dodecyldime$hylphosphine ox~de, tetradecyld1-methylphosphine ox~de, tetradecylmethylethylphosph~ne ox~de, 3,6,9-tr~oxaoctadecyldimethylphosphine oxide~ setyld~methylphos-ph~n2 ox~de, 3-dodecoxy-2-hydroxypropyldi(2-hydroxyethyl3 phos-phine ox1de, stearyldimethylphosphine oxide, stearyld~methyl-phosphine oxide, cetylethylpropylphosph~ne ox1d~, oleyldiethyl-phosphine oxide, dodecyldiethylphosphine oxide, t~tradecyldiethyl-phosphine sxide, dodecyld~propylphosph~ne ox~de, dodecyldi-(hydroxy~ethyl)phosphine oxide, dod~cyld1(2-hydroxyethyl)phosph~ne oxide/ tetradecylmethyl-2-hydroxypropylphosph~ne oxlde, oleyld~-methylphosph~ne oxide, 2-hydroxydodecyld~methylphosphlne ox~de.
6. Long chatn d~alkyl sulfoxides conta~n~ng one short cha1n alkyl or hyclroxyalkyl rad kal of 1 to about 3 carbon atom~
(usually methyl) and one lon~ hydrophob~c chain whkh conta~n alkyl, alkenyl, hydroxyalkyl, or keto alkyl rad1cals conta~ning from about 8 to about 20 carbon atoms, from 0 to about 10 ethylene oxide moietles and from 0 to I glyceryl molety. Examples lnclude octadecyl methyl sulfox~de, 2-ketotrldecyl methyl sulfox1de, 3,6,9,-trioxaoctadecyl 2-hydroxyethyl sulfoxtde, dodecyl methyl sulfoxide, oleyl 3-hydroxypropyl sulfox~d0, tetradecyl methyl sulfox1de, 3-methoxytridecyl methyl sulfoxlde, 3-hydroxytridecyl methyl sulfoxlde, 3-hydroxy-4-dodecoxybutyl methyl sulfox~de.
~ any addltional nonsoap surfactants, useful herein, are described ~n l~cCvtcheon's Detergents and E~u1sif7ers, 1979 Annua7, published by Allured Publ~shing Corporatlon.
The above-ment~oned surfactants can bQ used alone or in combinat~on in the shampso compos~tions of the present ~nventlon.
The ~nionic surf~otants, particularly the alkyl sulfates, the ethoxylated alkyl sulfates and m~xtures thereof, as ~ell as the iseth~onates, are preferred for use here~n. Most prefenred are the mixtures of alkyl sulfate and ethoxylated alkyl sulfate, wherein the rat~os of the former to the latter are ~rom about I:5 to about 5:I. Most preferred contains ammon~um lauryl sulfate and ammonium laureth sulfate.
~hen these surfactants are 1ntroduced into the compos~t~on lt ~s preferred they be ~ntroduced as mixtures hav~ng D surfactant concentrat~on of about 28X ~n the case of ammon~um laureth sulfate and about 25X ~n th~ ase of ammon~um lauryl sulfate. These concentratlons allow for optlmum processing of the shampoo compo-s1ttons.
In the present ~nvent10n, the ~ntidandruff active is a I-hydroxy-2-pyrldlnethtone sa~t ~n platelet part kle form, wherein the part1cles have an average s k e of from about 2 microns to about I5 m~crons, preferably from about 5 ~ k rons to aboue 9 mlcrons. The active 1s used at a level o~ from about 0.3X to about 2%, preferably about I%, of the shampoo composit~on. The I-hydroxy-2-pyr~dinethtone salts are d1sclosed for use ln ant~-dandruff shampoos tn U.S. Patent 2,809,971, Bernste~n, ~ssued - - 9 ~

October 15, 1957; U.S. Patent 3,236,733, Karsten et ~ ssued February 22, 1966; U.S. Patent 3,753,196, Parr~n, issued August 21, l973; U.S. Patent 3,761,418, Parr~n, issued September 25, 1973; U.S. Patent ~,345,080, Bolich, 1ssued August 5 l7, 1982; U.S. Patent $,323,6B3, Bol~ch et al., 1ssued April 6, l9R2; U.S. Patent ~,379,753, Bolich, 1ssued Aprll 12, l983; and U.S. Patent 4,470,982, ~inkler, tssued September 11, 1984.
The pyrid~neth~on2 salts useful here~n can generally be defined as water-~nsoluble salts of l-hydroxy-2-pyridinethione which has the following structural formula in tautomeric form, the sulfur being attached to the No. 2 position in the pyridine r;ng.
OH f ~ // S ~ SH

The salts result from substitution of the hydrogen of one of the tautomeric forms by the appropriate salt ~t~on. Depending, of course, on the valence of the salt cat10n 1nvolved there ma~ be more than one of the pyridineth~one r~ngs ~n the compound.
Preferred salts are formed from metals such ~s 21nc, tin, cadmium, magnes~um, ~luminium and z~rconium. The ~o~t preferred metal hereln is zlnc wh~ch forms 2-z~nc pyrlth~one or ~PT. Other cat~ons such as sod~um are ~lso su~table.
The pyrid~nethlone salts use~ul her~n take the fQr of water-~ nsol ubl e fl at pl atel et part~ cl es wh~ ch have ~ mean spher-icity of less than about 0.65, preferably from about 0.20 to about O.S~, and a medlan particle s~ze of from about 2 ~ to about 15 ~, preferably from about 5 ~ to about 9 ~, the particle size be1ng expressed as the median equ~valent d~ameter of a spher~ of equal volume. The med1an diameters are on ~ mass basis w~th 5C% of the mass of particles falllng on either side of the value giYen.
The diameter of a sphere of equ1valent volumæ for a part kle can be determined by ~ variety of sedimentat~on techniques ~hich are based on Stokes' Law for the settling veloc~ty of ~ partlcle in a fluid. Such techniques are descrlbed in Stockham, J.D. and Fochtman, E.G., Partic1e Si~e An~1ysis, Ann ~rbor Sc~ence, 1978 An approach for determining ehe median equivalent spherical diameter S based on volume, d , is shown in ~.S. Patent 4,345,080, Bolich, issued August 17, 1982, Example II.
The spherlcity of 2 part kle is also described by Stockham and Fochtman, supra, at page 113, as (dy/d5)2, where dy is the di~meter of a sphere of equivalent volume, supra, and ds is the diameter of a sphere of equivalent arlea. As used here1n, however, the mean sphericity is (dV/dS)2 or the surf~t~ area of spheres having equivalent volume distr~bution divided by the actual surface area o~ particles ~s measured. A tsehnlq~e for deter-mining actual surface area ls shown ln the examples us~ng the BET
techn~que described by Stockham and Fochtman, supr~, at page 122.
From the viewpoint of ant~dandruff eff~c~cy, the BET surface area herein preferably falls in the range of from about 0.5 to about 3.5 m2/g, ~ore preferably from about 1.0 to about 3.0 ~2/9.
The platelet 2-zinc pyrithione crystals preferred herein are made in the manner disclosed ln U.S. Patent ~,323,683, Bolich et al., issued Apr~l 6, 1982; U.S. Patent 4,345,080, æol kh, issued August 17, 1982; and U.S. Patent 4,37S,~53, Bolich, 1ssued April 12, ~g83 In add~tlon to the l-hydroxy-2-pyr1dlneth~one s~lts, the shampoo compos~tion dtsclosed herein may 1nolude other known antldandruff ~ctives. Such ant1dandruif actlves, when used, are included at levels of from about O.lX to about 1X of the compo-sition, and are selected from the group cons~stlng of hydroxy-pyridone salts, selenium disulfide, and mlxtures thereof.
Hydroxypyridone salts are known ant~microb~als. See Cosme-t1CS ~nd Drug Preservat70n, Princip7es and Pr~lctice, p ~2 ledited by J. Kabura, 198~) The hydroxypyridone salts used herein can generallv be described as 1-hydroxy-4-methyl-(1H)-pyridones having an allphat1c or aromatlc moiety (R) at the 6 pos~tion thereof, wherein R has a ~r factor of at least 1;3, preferably ~rom 2 ts 6, more preferabl~ from 3 to 5.5. The ~ factor ~s a measure of the llpoph~l~city/hydrophili-city of the substituent and ~s defined ln deta1l ln the paper by. Dittmar, E. Druckrey and H. Urbach, J. M~d. Chem. 17~7), 753-6(1974) and references c~ted there1n.
In structural terms, preferred R substituents ~re selected from llnear and branched C3-C1~, preferably C~-C~, alkyl and alkenyl groups, Cs-C, eycloalkyl 91-0UpS, and Cs C~ aryl groups.
The cyclic moiet~es, d~sc~ssed above, can also be subst1tuted with one or mor~ alkyl or ~lkenyl groups up to C~. Th~ R groups can - further be substituted w~th halogen atoms. Of the above, pre-ferred R moieties are cyclohexyl and 29~,4-trimethyl pentyl,the latter being highly preferred.
The abo~e ~entisned compounds can be used both ~n the free form and as salts, for example, salts ~th organic bases or inorganic cat~ons. Low ~olecular weight alkanolamines are espe-cially preferred organ k bases. ~he preferred hydroxypyridone salt for use herein is monoethanolamlne salt known ~s piroctone olamine or Octopirox; see Cosmetlc ~nd Drug Pres~rY~t~on, supra.
Piroctone olamine is descr1bed for use ~n deodor2nt composi-tions ~n Japanese Patent Appl k at~on Sho 57-10~,313, published December 23, 1983; Japanese Patent Appl1cation 5ho 5~-127,893, published Febru3ry 5, 1985 ~both to Lion) and U.S. Patent Appl~-cat~on Seri~l No. 314,62J, Melanson and Sturm, f1led tebruary 23, 1989. Japanese Patent Applicat~on Shc 57- 080,644 ~L~on), pub-lished November 18, 1983, discloses the use of a broad ~roup of hydroxypyrldone csmpounds for dandruff control.
The comb~nat~on of pyr~dineth~one and hydroxypyr1done com-pounds for use ~n ant1dandruff shampoos ~s known ln the art.
Japanese Patent Appl~cation Sho 58-198,413 (Lion~, published January, 1984 discloses ~ 12 -antidandruff shampoo compositions wh~ch 1nclude a combination of zinc pyridinethione ~nd piroctone olamine at a level from 0.05 to 5% by weight, wherein the rat~o of zinc pyr1dinethione to piroc-tone olamine is from 9:1 to l:9.
The pyridineth10ne/hydroxypyridone mixtures specif1ed here~n are generally used at levels of from about 0.4% to about 3X of the compos~tion. The we~ght ratio of pyridineth~one salt to hydroxy-pyridone ~s generally from about l:l to about S:l, preferably from about 2:1 to ~bout 3:1; most preferred ~s about 2.5:1.
Selenium disulfide is a medic~ne used ~n medicated sha~poos for tre~tment of seborrhea. U.S. f'atent 2,694,668, Baldw~n et al., issued November 16, 3954; U.S. Patent 3,lS2,046, Kapral, issued October 6, 1984; U.S. Patent 4,089,945~ 8r1nkman, issued May 16, 1978; and U.S. Patent 4,885,107, ~etzel, 1ssued Dece~ber 12, 1989, disclose selenium disulfide as the active lngredient in antidandruff shampoo compositions.
~ he pyridinethione/selenlum disulfide m~xtures specified here~n are generally used at levels of from about 1.25% to about 3% of the compos1t10n. The ratio of pyridineth~one salS So selenium disulfide is generally from about 1:4 to about 2:1, preferred 1s about 1:1.
$vner~
~ hen a synergi2er component, def~ned below, 1s co~bined w~th the sp~c1fled s k e pl~telet pyridinethione salts ~n a sha~poo, the shampoo's ant~dandruff eff k ~cy ls unexpectedly enhanced.
~hase synergi~ers are used at levels from about O.5X to about 5X, preferably fro~ about lX to about 3X and most preferably about ~%, of the co~posltlon, and are selected from the group consisting of specif~c polyethylene glycols (PEG~, polypropylene glycols (PPG), polyethoxy/polypropoxy copolymers (polyoxamers), polyethylen-imines, poly~thox~lated polyethylen~mines, polyethylene ox1de fatty glycerides, ethoxylated nonylphenols, ethoxylated alcohols, polyethylene oxide carboh~drttes, and mixtures thereof. Preferred synerg1zers here~n are the polyethylene glycols containing from about 6 to about 22 ethoxy groups, particularly those having a molecular weight from about 280 to about 1000. An especially preferred synergizer ~s PEG-12, with a molecular weight of about 546.
PEG and PPG are known for use ln shampoos as v~scos~ty I modifiers. See Goldemberg, Adv~nces~in Cosmetic rechno10g~, Vol.
: 1 p. 70-71 (Ig78), ~he PEG for use 1n the present invent~on has the formula H(OCH2 -CH2 ) nOH
wherein n ls from about 6 to about ~2; preferably from about 6 to about 18. Most preferred is PEG-12 wherein n has the average value of 12, available as Carbowax 600, from Union Carbide;
, Polyglycol E-600, from Dow Chemical USA; and Pluracol -600, from I BASF-Wyandotte.
I 15 The PPG used ~n the present invention has the formula [ Ctl~
. wherein n is from about 6 to about 2?, preferably fro~ about 6 to S`'?`i 20 about 18. Most preferred ~s PP6-12 wherein n has the averagevalue of 12, ava~lable as Pluracol P-710, from BASF-Wyandotte.
Polyoxamers are polyoxyethylene/polyoxypropylene block polymers, which are useful here~n as synergizers. An example of such a block polymer has the formula ; 25 Ho(cH2cH2o)x(fHcH2o)y (CH2CH20)zH
C~
where~n the total of x + z is from about 38 to about 156, and y is fro~ about 30 to about 54. The block polymers also include polymers which have the propoxy, ethoxy, propoxy chain orienta-tion. These synergizers are available from 8ASF-Wyandotte as Pluronics. Preferred for use herein ~s Pluron~c F-68.
Other synergizers useful herein include polyethylenimlnes whlch are disclosed in U.S. Patent 39761,417, Parran, issued September 25, 1973.,. These polyethylenlminès generally have the . .
formula H2(N-CH2-CH2)n~NH2 , I B * Trademarks j wherein n is from about 6 to about 22, preferably from about 6 to ¦ about l8. Examples of these are PEI ? and PEI 15.
- I Ethoxylated polyethylenimines are also useful herein as synergizers. Such compounds are disclosed ~n Parran cited supra.
These synergizers have the formula H(FO)XfN-CH2-CH~N(EO)x-H
l!EO) H J(IEO~XH
wherein y ~s from about 6 to about 22 and the ethoxylate groups x are independently from about 10 to about 30. An e%ample of th~s is ethoxylated tetraethylene pentam~ne.
Ethoxylated nonylphenols ,are a1so useful herein as syner-gizers. These synergizers are non~onic surfactants having the formula c9Hlgc6H4(ocH2cH2)noH
where~n n is from about 12 to about 50. Sa~d synerglzer ~s also i known as nonoxynol. Preferred for use herein ls Nonoxynol ~ 0.
Polyethylene oxide fatty glycerides also synergize the I actives 1n the shampoo compos~tions d~sctosed here~n. Said synergizers have the formula I
(EO)nH (Eo)nH (E)nH
where~n E0 represents -(CH2-CH2-0-)- and each n 1s 1ndependently 1 25 from about 0 to about 9 with no fewer than one ethoxy group in the compound. Such ethoxylated glycerides are available fro~ TCI
Americas Incorporated as Arlatone G or PEG-40 Sorbitan Peroleate.
Polyethylene oxide carbohydrates may also be used to syner-i gize the actives herein~ Said synergi~ers have the formula * ~rrademarks :
.
......

' , . ' '~ ' , . . .

.
. . . . . . . .

- ls -~(ocH2cH2 )V-OH
l~ I
(OCH2CH2)W-OH
CH-(OCH2CH2)xOH

CH2(0CH2CH2)yO~C(CH23zCH3 wherein the total v + w ~ x ~ y i~s from about 4 to about 20 and 2 is from about 10 to about 18. Sa~d compounds, wh~ch are known for use in hair care products as co-surfactants and suspending agents, include the polysorbates available from ICI Americas as ~ween.
Preferred ~s Tween-20*
Lastly, ethoxylated straight chain alcohols synergize the antidandruff actives disclosed here1n. Sa~d synergizers have the formula R(OCtl~CH2 ) nOH
I wherein n ls from about 20 to about 55. These compounds are available from BASF ~yandotte as Plurafacs. Preferred ~s Plurafac A-39.
SusDendinq Anents The composit~ons of the present inventlon conta1n a sus-pendins agent. Examples of suit~ble suspending agents include xanthan gum, long chain (C16-C22) acyl derivat~ves, long ehain 2,5 (Cl6-C22) amine o~ides, and mixtures thereof, as are disclosed by -U.S. Patent 4,~04,2729 Oh et al., lssued November 3, 19~7~
T~e pwe~erred~su~spend~g ~ge~ts ~e the eth~lene glycol esters as dlsclosed ~n U,S~ Patent 4,885~107~ ~etzel, issued Decem~er 57 198~. ~ost preferred are the diesters compris~ng a mi~xture of palm~tate and s~tearate~ The amount of stearate should Be ~n the range of a~out 10% to aB-out 42% or ~n the range of aBout 55% to about 80% wi~th palmitate account2ng ~or the remai~nder. The amount of stearate ~s pre~era~-ly~from about 60%
to aBout 75%.

* Trademarks ~B~

.

. : ~ . .. .. : . . .
. -~ - .. - . . . ~
.. . . . . . . . -. . . . .
. . . ~ . .

2~37~

The amount of the ethylene glycol d~0ster useful in the presen~ invention ~s from about 0.5~ to about 6%, preferably from about 1% to about 4%.
Water ~ater is the last essent1al component of the present invention and forms the remainder of the compos~tion. It ls generally present at a level of from about 20% to about 90%, preferably from about 60~ to about 35%, o~ the final composition.
Optional Comwnents The shampoos herein can contain a variety of nonessential optional components suitable for rlendering such composltion more cosmetically, aesthetically, or functionally acceptable. Such conventional optional lngred1ents, well known to those skilled in th~ art, include preservative~, such as benzyl alcohol, methyl paraben, propyl paraben and imidazolidinyl urea; cationic surfac-tants, such as cetyl trimethyl ammonium chloride, lauryl trimethyl ammonium chloride, trlcetyl methyl ammonlum chloride, stearyldi-methyl benzyl ammonium chloride, and di(part~ally hydrogenated tallow) d;methylammonium chloride; pH ad~ust;ng agents, such as citric acid, succinic acid, phosphoric acid, sodium hydroxide, and sodium carbonate; perfumes; ~nd dyes. Such opt~onal ingred~ents generally are used lndividually at a level of from about 0.01% to about 10%, preferably fro~ about 0.5% to about 5%, by weight of the composition.
The amides may be used ~n lotion form shampoo compositions.
Amides for use herein ~nclude alkanolamides of fatty aclds known for usein shampoos as emulslflers. Said amides enhance lathering and are generally mono- and diethanolamides of fatty acids hav~ng from about 8 to about 14 carbon atoms. Preferrad are coconut monoethanolamide, coconut diethanolamide, and mixtures thereof.
Other amides are those having multiple ethoxy groups such as PEG-3 lauramide.
When used, the amide is present at a level of from about 1%
to about 7X, preferably from about 2X to about 5Z, of the shampoo composition.

. . . .

Sil~cone compounds may be incorporated ~nto the sh~mpoo composltions to ~mpart condition1ng benefits to the hair. Such silicone compounds are disclosed in U.S. Patent 2,8~6,551, Geen, issued March ~ 958; U.S. Patent 3,964,500, Drako~f, lssued ~une S 22, 1976; U.S. Patent 4,152,416, Sp~tzer, issued May 1, 1976; U.S.
Patent 4,364,837, Pader, lssued December 21, 1982; U.S. Patent 4,221,688, Johnson et al., issued September 9, 1980; U.S. Patent 4,515,784, eogardus et al., issued May 7, 1985; U.S. Patent ~,704,272, Oh et al., lssued November 3, 1987; U.S. Patent 1~ 4,~28,457, Fieler et al., issued March 1, 1988; U.S. Patent 4,741,855, Grote et al., issued May 3, 1988; U.S. Patent 4,764,363, ~olich, issued August 16, 1988; U.S. Patent 4,788,096, Bol~ch et al., issued November 29, 1988; U.S. Patent ~,a34,g68, Bol kh, 1ssued May 30, 1989; and U.S. Patent 4,842,850, Vu, lssued June 27, 1989.
Non-volatlle silicone ~ontaining compoun~s are preferred herein and are used at levels of from about O.lZ to about 10X, preferably fro~ about 0.25% to about 3X, by weight of the compo-sition. Non-volatile silicones are selected from the group consisting o~ polyalkyl siloxanes, polyaryl aryl siloxanes, polyether siloxane copolymers and mixtures thereof.
Polyalkyl slloxanes useful here~n lnclude, for example, polydimethyl siloxanes (PDMS) with vlscosities ranging from about 5 to 15,000,000 centipoise (cp) at 25~C. These slloxanes are ava~lable, for example, ~rom the ~eneral Electr k Company as the Viscasll ser1es and from Dow Corning as the Dow Corning 200 series. ~he viscosity can be measured by means of a glass cap~l-lary viscometer as set forth ~n Dow Sorn~ng Corporate ~est Method CTM0004, July 20, 1970.
Polyalkylaryl s11axanes that may be used include polymethyl-phenyl s110xanes having v~scosities of from about 5 to about lS,OOO,OOO cp at 25-C. These s~loxanes are ava11able, for ex-ample, from the ~eneral Electrk Company as SF 1075 ~eth~l phenyl fluid or from DDW Corning as 556 Cosmetic Grade Flu~d.
Polyeth~r siloxan~ copolymers that may be used ~nclude polypropylene oxide ~dified polydimethyls~loxanes. These are ' available, for example, from Dow Cornlng as DC-1248. Ethylene oxide or mixtures of ethyl~ne oxide and propylene oxlde may also be used. The water insoluble ones are preferred.
Generally, these silicone compounds descr~bed above condition the hair. The csnditioning benefit is due to the ~b111ty of the siloxanes to lubricate the hair providing wet ~nd dry combing benefits. Viscous, higher molecular we~ght s~loxanes prov1de the best condit~oning benefits and are theref~re preferred for use ~n the present shampoo compositlon. It has been found that gums of the above described siloxane polymers are most des~rabl~ for use herein. These siloxan~ polymer gums are rigid as opposed to a liquid or flu~d, with high mass molecular weights of from about 200,000 to about 1,000,000 and v~scosi~es from about IOO,OOO cp to about I50,000,000 cp at 25-C. Such gums ~re discussed 1n det~ll 1n ~. Noll, Chemistry dnd Techno10g~ of 51'~fcones, New ~ork Academic Press, 1968; and General Electric, Sil~cones and Rubber Product Data Sh~et SE30, SE33, SE54 and SE76; and Mark, B~kal~s, Overberger, Mengle, ncyclopedia of Science and Engineering, Yol.
15 (2d ed., I989) .
In the present invention the polydimethyl siloxane gums are preferred. These gums have a viscosity of from about 100,000 cp to about 5,000,000 cp at 25C. The gums selected for use herein have a viscosity such that when blended with a PDMS fluid the viscosity of the blend of gum and fluid falls within this range.
Such PDMS fluids used for the blending of the gum are those disclosed in U.S. Patent 4,834,968, Bolich, issued May 30, 1989.
Such PDMS fluids are used at levels from about 50% to about 60%
of the total weight of said gum-fluid blend. Most preferred for the present lnvention is a blend containing from about 40% to about 60% PDMS fluid/Erom about 60% to about 40% PDMS gum. The preferred PD~S fluid ts dimethicone fluid which has a viscosity of about 350 cp at 25C. Most preferred PDMS gums are those avail~
able from The General Electric Com~any.

'" A~

7 ~ ~

Viscosity modifiers may be added to the shampoo compositions disclosed here;n. Shampoos with viscositles from about 2,000 cp to about 12,000 cp at 25-C generally in the form of lotions offer the best cosmetic and aesthetic advantages to users. In the present invention, hydrotropes may be used as viscosity modif~ers.
These are selected from the group consisting of aryl sulfonates, such as ammonium xylene sul~onate; alcohols, such as polyvinyl alcohol, and ethyl alcohol; salts, such as sodium chloride, and ammonium chloride; and mixtures thereof. Some of the synergizers, such as polyethylene glycol, polypropylene glycol, polyethoxy/
polypropoxy copolymers and polyethylenimines may also have vis-cosity modifying effects; in some circumstances the above de-scribed viscosity modifiers may additionally be ~ncluded at from about 1% to about 5% of the sh~mpoo, to brlng the viscos~ty of the final compositions within the range disclosed abov~.
Method of Manufacture The antidandruff shampoo compositions disclosed herein may be made by various processes generally known in the art. All of these processes require making a number of premi%es which are eventually eombined with a main mix.
The surfact~nts preferred for use, ammonium lauryl sulfate (ALS) and ammonium laureth sulfate (AE3S), are prem1xed. The ALS
mixture contalns about 25X ALS, about 0.3X preservat~ve and the rest water. The AE3S mixture is about 28X AE3S, 0.3% preserva-tive, about 4% vlscosity modifler and the re~t water. Somesynergizers may modify the viscosity. ~hen these synergizers are used, they should be added to the AE3S premi~ at a level necessary to achieve desired viscosity. The remainder of th~ synergizer required to enhance the antidandru ff act~vity is added with those actives. The surfactant premixes, as well as the fatty alcohols, the am;de and suspending agents, are mixed together to for~ the main mix. Various other pr~mixed ingred~ents are added to th1s main mix at various processing points, as described below.
The ZPT active is added to the main mix as a slurry.
Additional antidandruff actives, (e.g., selen~um disulfide, , ' ~ ' ~ :

- 2~
piroctone olamine or mixtures thereof~ may be added along ~ith the ZPT s~urry.
If a silicone gum/fluid blend is to be used, it ~s made as a premix together with other shampoo ingredients to facil itate the uniform dispersion of said blend in the main mix.
Method of Use The present compositions are used in a conventlonal manner for cleaning ha~r. From about 0.1 9 to about 20 ~ of the co~po-sition is applied to ha~r that has been wetted, generally ~ith ~ater, washed throu~h the hair and rlnsed out. Said method of use is repeated until the hair is clean.
EXAMPLES
The following examples illustrate the compos~tions of the present invention.
E%amples II III IV V YI
ComPonent Ammonium Laureth Sulfate14.94 14.94 3.15 1~.94 14.94 3.15 Ammonium Lauryl Sulfate 3.15 3.15 14.9~ 3.15 3.15 14.94 A~monium Xylenesulfonate - 3.00 3.00 - 3.00 3.00 Ethylene Glycol Distearate 3.00 3.00 3.00 3.00 3.00 3.00 Coconut Monoethanolamide2.58 2.58 2.58 2.58 2.58 2.58 Polyethylene 61ycol 12 (molecular wt. 546) 2.00 - - 2.00 - -Polypropylene Glycol - 1~
(molecular wt. 714) - 2.00 PE6-40 Sorbitan Peroleate - - 2.00 Nonoxynol-15 - - - - 2.00 PEI-15 (molecular wt. 645) ~ 2.00 Silicone Gum 1 0.5 0.5 0.4 0.5 0.5 0.
Dimethicone Fluld (350 cp at 25-C) 0.5 0.5 0.6 0.5 0.5 0.6 2-Zinc Pyrithione (platelets, mean part~cle size of 7.7 ~) 1.0 1.0 1.0 1.0 1.0 1.0 2~1 37~

Piroctone Olamine - 1.0 - O.S 0.75 0.25 Selenium Disulflde - - 1.0 O.S 0.25 0.75 Cetyl Alcohol 0.42 0.42 0~6 0.42 0.42 0.60 Stearyl Alcohol 0.18 0.18 0.3 0.18 0.18 0.30 Color, perfu~e, preservat~ve, pH control agent and water Q.S. to 100 ~ Silicone gum available from General Electr k Co. as the Viscasil Series.
The above examples are made using the procedure that follows.
Prepare a silicone pre-mix b,y putt~ng about 2X of the ammo-nium laureth sulfate ~nto a process tank and heating to from about 74-C to about 80~0. Add abo~t 0.3X of the cetyl alcohol, about O.lX of stearyl aloohol and the silicone gum/fluld blend to the tank. Continue to mix unt~l all solids are melted and the mixture lS is uniform.
In a second process tank, add ammon~um lauryl sulfate and about 2Z ammon~um laureth sulfate. Heat, while m~x~ng, to fro~
about 74-C to about 80'C. Add the r~st of the cetyl alcohol and stearyl alcohol, as w~ll as the coconut monoethanolamidet ethylene glycol d1stearatQ, preservat~ves, and water. Onee this ~s thor-oughly blended, add the silicone premix. M~x unt~l uniform and cool mixture to about 42-C.
Add the rema~ning ~n~nonium laureth sulfate, the ZPT slurry, other add1t~onal act~ves, such as selentum d~sul~d~, piroctone olamine, and mixtures thereof, the synerg1z~r, perfume, color and water to the ma1n mix tank. M~x until uniform and pump into storage containers.
When hair is washed w~th any of the aboYe hampoo compo~
sitionsl excellent cleaning and ant~dandruff eontrols ar~
30 obtai ned .
Exampl es VII VIII IX X XI XII
Com~onent Anunonium Laureth Sulfate 11.92 11.9211.92 11.92 11.9211.92 Ammonium Lturyl Sulfate 10.42 10.4210.42 10.42 10.4210.42 , . . , ' . . :

Ethylene Glycol Distearate3.00 3.00 3.00 3.00 3.00 3.00 Coconut Monoethanolamide 3.44 3.~4 3.44 3.4~ 3 4~ 3 44 Polyethylene Glycol-12 (molecular wt. 546) 5.00 3.0 Polypropylene Glycol - 12 (molecular wt. 714) - - 5.0 Polyoxamer - 105 - - - S 0 Ceteareth - 12 - - - - S 0 Polysorbate 20 - - - - 5 0 Ammonium Xylene Sulfonate - 2.0 2.0 2.0 - 2.0 2-Zinc Pyrithione (platelets, mean particle size 0~ 7.7~ 1.0 1.0 1.0 1.0 1.0 Piroctone Olamlne - 1.0 - 0.5 0.75 0.25 Selenium Disulfide - - 1.0 0.5 0.25 0.75 Color, perfume, preservative, pH control and water Q.S. to lOOK
The fsllowing procedure is used to make Examples Vll to XII.
Add the ammonlum lauryl sulfate to a pre-m1x tank and heat to from about 6S-C to about 77-C. Add preservatiYe, color, coconut monoethanolam~de allow~ng the solid to ~elt 1nto solut10n. Add ethylene glycol distearate allowing the sol~d to melt into solu-tlon. Add amm~nium xylene sulfonate, a synergizer, or both. Add water and mix untll uniform, ~ooling to about 29-C.
The prem1x ls then and added to the ma~n m~x tank. Add the ZPT slurry, other additional actiYes, such as selenium disulfide, piroctone olam~ne and mixtures thereof, synergizer, ammonium laureth sulfat~, and water to the ma~n ~ix tank. M~x until uniform and pump into stsrage containers.
When the ha1r is washed with any of the above shampoo compo-s~tions, excellent clean~ng and dandruff control are obta~ned.

.

.
.

Claims (23)

1. An antidandruff shampoo composition in lotion form comprising:

(a) from about 5% to about 70% of a synthetic surfactant;

(b) from about 0.3% to about 2% of 1-hydroxy-2-pyridinethione metal salt in platelet form having a mean particle size of from about 2 microns to about 15 microns;

(c) from about 0.5% to about 5% of a synergizer selected from the group consisting of:

(1) polyethylene glycols having the formula H(O-CH2-CH2)nOH

wherein n is from about a to about 22;

(2) polypropylene glycols having the formula wherein n is from about 6 to about 22;

(3) polyethoxy/polypropoxy block copolymers;

(4) ethoxylated nonylphenols having the formula C9H19C6H4(OCH2CH2)nOH

wherein n is from about 40 to about 50;

(5) polyethylene oxide fatty glycerides having the formula wherein (EO) represents an ethoxy group and each n is independently from about 0 to about 9, with the total number of ethoxy groups in the compound being not less than 1.

(6) polyethylene oxide carbohydrates having the formula wherein the total of v+w+x+y is from about 4 to about 20, and z is from about 10 to about 18.

(7) ethoxylated straight chain alcohols having the formula R(OCH2CH2)nOH

wherein R represents a blend of cetyl and stearyl radicals, and n is from about 20 to about 55; and (8) mixture thereof;
(d) from about 0.5% to about 6% of a suspending agent; and (e) the remainder water.

2. An antidandruff shampoo composition according to claim 1 wherein the synergizer is selected from the group consisting of polyethylene glycol containing from about 6 to about 22 ethoxy groups, polypropylene glycol containing from about 6 to 22 ethoxy groups, and mixtures thereof.

3. An antidandruff shampoo composition according to claim 2 additionally comprising from about 0.1% to about 10% of a nonvolatile silicone selected from the group consisting of polydimethyl siloxanes, polypropylene oxide dimethyl siloxane copolymers, and mixtures thereof, having viscosities from about 5 to about 150,000,000 centipoise at 25°C.

4. An antidandruff shampoo composition according to claim 3 additionally comprising from about 0.1% to about 1% of a second antidandruff agent selected from the group consisting of selenium disulfide, piroctone olamine, and mixtures thereof.

5. A shampoo composition according to claim 3, in lotion form, additionally comprising from about l% to about 7% of an emulsifier selected from the group consisting of mono- and diethanolamides of fatty acids having from about 8 to about 14 carbon atoms.

6. A method of shampooing hair comprising applying to the hair that had been wet with water, from about 0.1 g to about 20 g of a composition according to claim 3, working the composition through the hair, and rinsing it from the hair.

7. An antidandruff shampoo composition according to claim 3 wherein the suspending agent is selected from the group consisting of xanthan gum, long chain (C16-C22) acyl derivatives, long chain (C16-C22) amine oxides, and mixtures thereof [at a level from about 0.5% to about 5%].

8. An antidandruff shampoo composition according to claim 7 wherein the suspending agent is an ethylene glycol C16-C22 diester.

9. An antidandruff shampoo composition according to claim 3 wherein the non-volatile silicone is a mixture of from about 40% to about 60% silicone gum and from about 60% to about 40% polydimethyl siloxane fluid wherein the viscosity of the mixture is from about 5 to about 2000,000 centipoise at 25°C.

10. An antidandruff shampoo composition according to claim 9 wherein the silicone gum has a molecular weight between about 200,000 and about 1,000,000.

11. An antidandruff shampoo composition according to claim 10 wherein the polydimethyl siloxane has a viscosity of about 350 centipoise at 25°C.

12. An antidandruff shampoo composition according to claim 3 wherein the synthetic surfactant is selected from the group consisting of anionic surfactants, non-ionic surfactants, zwitterionic surfactants, amphoteric surfactants, and mixtures thereof.

13. An antidandruff shampoo composition according to claim 12 wherein the synthetic surfactant is anionic.

14. An antidandruff shampoo composition according to claim 13 wherein the anionic surfactant is a mixture of (a) allyl sulfate and (b) ethyoxylated allyl sulfate, having a ratio of (a) to (b) from about 5:1 to about 1:5.

15. An antidandruff shampoo composition according to claim 14 wherein the alkyl sulfate is ammonium lauryl sulfate and the ethoxylated allyl sulfate is ammonium laureth sulfate.

16. An antidandruff shampoo composition according to claim 3 wherein the pyridinethione salt is 2-zinc pyrithione.

17. An antidandruff shampoo composition according to claim 16 wherein the 2-zinc pyrithion platelets have a mean particle size of from about 5 microns to about 9 microns.

18. An antidandruff shampoo composition according to claim 16 additionally comprising from about 1% to about 5% of a viscosity modifier selected from the group consisting of aryl sulfates, alcohols, salts, and mixtures thereof.

19. An antidandruff shampoo composition according to claim 16 wherein the synergizer is a polyethylene glycol containing from about 6 to about 18 ethylene oxide groups.

20. An antidandruff shampoo composition according to claim 19 wherein the 2-zinc pyrithione has a mean particle size of from about 5 microns to about 9 microns.

21. An antidandruff shampoo composition according to claim 20 wherein the synergizer is present at from about 1% to about 3% the composition.

22. An antidandruff shampoo composition according to claim 21 wherein the synergizer is a polyethylene glycol having the formula H(OCH2-CH2)nOH wherein n has an average value of 12.

23. A method of shampooing hair comprising applying to the hair that has been wet with water, from about 0.1 g to about 20 g of a composition according to claim 22, working the composition through the hair, and rinsing it from the hair.