Hair Treatment

Antimicrobial suspensions and antimicrobial hair treatment compositions

Hair Treatment Abstract
A polyvalent metal salt of 2-mercaptopyridine-N-oxide (Mept compound) is dispersed in water by aid of a specific dispersant selected from the group consisting of (A), (B) and (C): (A) A polyglycol/polyamine condensation polymer, polyglycol/polyamine/alkylamine condensation polymer or alkyleneamine condensation polymer; (B) At least one water-soluble polymer compound selected from the group consisting of hydroxyalkylcelluloses and partly quaternarized products thereof, and at least one non-ionic surfactant; (C) At least one cationic polymer compound and at least one inorganic salt. The resulting suspension has improved stability and is applicable to shampooes, hair rinses and the like.

Hair Treatment Claims
What is claimed is:

1. An antimicrobial suspension, comprising:

(1) an antimicrobial effective amount of a fine particulate metal salt of 2-mercaptopyridine-N-oxide, Mept, wherein said metal is selected from the group consisting of magnesium, barium, strontium, zinc, cadmium, tin and zirconium, and wherein said particulate metal salt has a size distribution in which particles having a size below 0.2 .mu.m are contained in amounts of at least 50 wt %, and has an average size below 0.16 .mu.m, and

(2) a dispersant or mixture of dispersants selected from the group consisting of (A), (B) and (C):

(A) a polyglycol/polyamine condensation polymer, polyglycol/polyamine/alkylamine condensation polymer or alkyleneamine condensation polymer in an amount of from 1/100 to 10 times the fine particulate Mept compound on a weight basis;

(B) a water-soluble polymer compound selected from the group consisting of hydroxyethylcellulose, hydroxypropylcellulose and quaternized derivatives thereof in an amount of 5 wt % or more of the fine particulate Mept compounds, and at least one nonionic surfactant in amounts of 5 wt % or more of the water-soluble polymer compound; and

(C) at least one cationic polymer selected from the group consisting of the following compounds of (a), (b), and (c), an amount of said cationic polymer being from 0.1 to 60 wt % in an aqueous solution:

(a) a copolymer-type cationic polymer compound of dimethyl diallylammonium halide and acrylamide represented by one of the following formulas: ##STR21## wherein R.sub.25 and R.sub.26 are the same or different and independently represent a hydrogen atom or methyl group, X represents a halogen atom, and l and m.sub.4 are integers such that the sum of l and m.sub.4 ranges from 180 to 2,000;

(b) a polycondensation product of adipic acid and dialkylaminohydroxypropyl diethylenetriamine represented by the following formula or quaternized products thereof: ##STR22## wherein, R.sub.27 and R.sub.28 are the same or different, and independently represent an alkyl group having 1 to 18 carbon atoms, and n.sub.4 is an integer that gives a molecular weight of ranging from 332 to 100,000; and

(c) a copolymer represented by the following formula or quaternized products thereof: ##STR23## wherein, R.sub.29 represents a hydrogen atom methyl group or ethyl group, Z represents an oxygen atom or a group --NH--, R.sub.30 represents an alkylene group having 1 to 4 carbon atoms, R.sub.31 and R.sub.32 are the same or different and independently represent an alkyl group having 1 to 18 carbon atoms, and p and q independently represent integers that give a molecular weight ranging from 1,000 to 5,000,000, and

an inorganic salt selected from the group consisting o alkali metal salts, alkaline earth metal salts, and aluminum salts of hydrochloric acid, sulfuric acid, or nitric acid in an amount of from 0.1 to 25 wt % in an aqueous solution.

2. The antimicrobial suspension according to claim 1, wherein said fine particulate polyvalent metal salt of 2-mercaptopyridine-N-oxide has a size distribution in which particles having a size below 0.2 micron are contained in amounts not smaller than 50 wt %, particles having a size ranging from 0.5 to 1.0 micron are contained 15 wt % or less, and particles having a size not smaller than 1.0 micron are contained 2 wt % or less.

3. The antimicrobial suspension according to claim 1, wherein said polyvalent metal salt of 2-mercaptopyridine-N-oxide is a zinc salt.

4. The antimicrobial suspension according to claim 1, wherein said polyvalent metal salt of 2-mercaptopyridine-N-oxide having a size distribution in which particles having a size below 0.2 micron are contained in amounts not smaller than 50 wt % is incorporated in said suspension by 0.0015 to 60 wt %, and said dispersant (A) is incorporated in said suspension by 1/100 to 10 times of the amount of said fine particulate polyvalent metal salt of 2-mercaptopyridine-N-oxide.

5. The antimicrobial suspension according to claim 1, wherein said fine particulate metal salt of 2-mercaptopyridine-N-oxide hss an average size of from 0.05 to 0.16 microns.

6. The antimicrobial suspension according to claim 1, wherein said fine particulate metal salt of 2-mercaptopyridine-N-oxide has an average size of from 0.05-0.08 microns.

7. An antimicrobial hai treatment composition containing an antimicrobial suspension, which comprises:

(1) an antimicrobial effective amount of a fine particulate metal salt of 2-mercaptopyridine-N-oxide, Mept, wherein said metal is selected from the group consisting of magnesium, barium, strontium, zinc, cadmium, tin and zirconium, and wherein said particulate metal salt has a size distribution in which particles having a size below 0.2 .mu.m are contained in amounts of at least 50 wt %, and as an average size below 0.16 .mu.m, and

(2) a dispersant or mixture of dispersants selected from the group consisting of (A), (B) and (C):

(A) a polyglycol/polyamine condensation polymer, polyglycol/polyamine/alkylamine condensation polymer or alkyleneamine condensation polymer in an amount of from 1/100 to 10 times the fine particulate Mept compound on a weight basis;

(B) a water-soluble polymer compound selected from the group consisting of hydroxyethylcellulose, hydroxypropylcellulose and quaternized derivatives thereof in an amount of 5 wt % or more of the fine particulate Mept compounds, and at least one nonionic surfactant in amounts of 5 wt % or more of the water-soluble polymer compound; and

(C) at least one cationic polymer selected from the group consisting of the following compounds of (a), (b), and (c), an amount of said cationic polymer being from 0.1 to 60 wt % in an aqueous solution:

(a) a copolymer-type cationic polymer compound of dimethyl diallylammonium halide and acrylamide represented by one of the following formulas: ##STR24## wherein R.sub.25 and R.sub.26 are the same or different and independently represent a hydrogen atom or methyl group, X represents a halogen atom, and l and m.sub.4 are integers such that the sum of l and m.sub.4 ranges from 180 to 2,000;

(b) a polycondensation product of adipic acid and diallylaminohydroxypropyl diethylenetriamine represented by the following formula or quaternized products thereof: ##STR25## wherein R.sub.27 and R.sub.28 are the same or different, and independently represent an alkyl group having 1 to 18 carbon atoms, and n4 is an integer that gives a molecular weight of ranging from 332 to 100 000; and

(c) a copolymer represented by the following formula or quaternized products thereof: ##STR26## wherein R.sub.29 rppresents a hydrogen atom, methyl group or ethyl group, Z represents an oxygen atom or a group --NH--, R.sub.30 represents an alkylene group having 1 to 4 carbon atoms, R.sub.31 and R.sub.32 are the same or different and independently represent an alkyl group having 1 to 18 carbon atoms, and p and q independently represent integers that give a molecular weight ranging from 1,000 to 5,000,000, and

an inorganic salt selected from the group consisting of alkali metal salts, alkaline earth metal salts, and aluminum salts of hydrochloric acid, sulfuric acid, or nitric acid in an amount of from 0.1 to 25 wt % in an aqueous solution.

8. The hair treatment composition according claim 7, wherein said composition is a shampoo composition or a hair rinse composition.

9. An antimicrobial hair treatment composition according to claim 7 or claim 8, wherein said hair treatment composition comprises a surfactant for shampoo use containing a mixture of one or more agents selected from the group consisting of anionic surfactants, amphoteric surfactants, non-ionic surfactants and cationic surfactants.

10. The antimicrobial hair treatment composition according to claim 9, wherein said surfactant for shampoo use is contained in an amount of 5 wt % or more based on the total composition.

Hair Treatment Description
BACKGROUND OF THE INVENTION

(i) Field of the Invention

This invention relates to aqueous suspensions of antimicrobial agents and antimicrobial hair treatment compositions in which fine particulate polyvalent metal salts of 2-mercaptopyridine-N-oxide (which may be hereinafter referred to simply as Mept compounds) having a specific size distribution are stably dispersed.

(ii) Description of the Prior Art

Polyvalent metal salts of 2-mercaptopyridine-N-oxide are known to be effective as antimicrobials and are widely utilized not only as ordinary antimicrobials, but also as anti-dandruff agents and are incorporated into shampoo compositions, hair rinse compositions and the like. The polyvalent metals of the Mept compounds are magnesium, barium, strontium, zinc, cadmium, tin, zirconium and the like. Of these, zinc salts are widely used.

However, these Mept compounds are sparingly soluble in water, for instance, the zinc salt (hereinafter referred to simply as Zpt compounds) has a solubility in water of 15 ppm at 25.degree. C. Accordingly, when they are incorporated into shampoo or hair rinse compositions, they must be utilized in a form of dispersions.

However, because of the considerable difference between the specific gravities of Zpt compounds (specific gravity =1.8) and a medium liquid for dispersion, the Zpt compounds are apt to settle and separate as time passes, and thus it was difficult to obtain a stable dispersion system containing Zpt compounds.

In order to prevent such settlement or separation, the following methods are known:

(i) Make the static viscosity of the dispersion medium high.

(ii) Make the particle size of Mept compounds so small that Brownian movemett will be dominant in the system.

By either method, settlement will be made difficult to take place.

Examples of method (i) are a method of adding viscosity increasing polymers such as cross-linked polyacrylates (Japanese Patent Publication No. 49-49117) and a method of adding acrylic acid/acrylate copolymers (Japanese Patent Publication No. 54-16951). However, these methods have the drawback that limitation is placed on the type of surface active agent usable to stably disperse Mept compounds.

As for method (ii), since Mept compounds having very small particle size are difficult to be produced, compositions containing fine particulate Mept compounds stably dispersed therein have not been practically obtained.

Under such conditions, the present inventors formerly made a study and succeeded in manufacturing Mept compounds having very small particle size (hereinafter referred to as fine particulate Mept compounds) compared with conventional Mept compounds incorporated into shampoo or hair rinse compositions (Japanese Patent Application Nos. 58-122845, 58-122846 and 59-82690).

The present inventors made further study in order to obtain stable antimicrobial suspensions making use of thus obtained fine particulate Mept compounds, and found that fine particulate Mept compounds are very sensitive to conditions of liquid media for dispersion and are apt to coagulate, leading to difficulty in keeping the original size distribution. More specifically, the following phenomena were noted.

(1) Fine particulate Mept compounds in a suspension coagulate when electrolytes such as salts are included in the suspension, or when the suspension is got frozen or heated.

(2) Fine particulate Mept compounds are apt to coagulate when they are incorporated into hair treatment compositions such as shampooes o hair rinses in which surfactants are contained, because the surfactant per se is an electrolyte.

In order to prevent the coagulation of fine particulate Mept compounds, surface modification or colloidal protection have been proposed.

Examples of adding a water-soluble polymer to a shampoo composition which incorporates Mept compounds are disclosed in Japanese Patent Publication Nos. 47-20635 and 50-22044, in which cationic polymers are used as a water-soluble polymer in order to enhance the adsorption of Mept compounds to the hair and head skin. However, the cationic polymers function as a coagulating agent for fine particulate Mept compounds having a specific size distribution, and produce considerable coagulation.

The method of forming colloid layer of cellulose-type water-soluble polymers for protection also has a drawback in that the cellulose polymers coagulate when they form a colloidal adsorption layer on a particle to be protected. For instance, additinn of an aqueous solution of hydroxyalkylcellulose or the like, which is referred to in Japanese Patent Application Laid-Open Nos. 53-14710, 53-14711, 53-97010 and 57-176906, results in losing the original size distribution, leading to losing the stable dispersability.

From this reason, conventional art was directed to make use of cellulose-type water-soluble polymers as a thickner to enhance the viscosity of shampoo base thereby allowing the incorporated fine particulate Mept compounds to settle more slowly, or further incorporating swelling clay or pearling agent in order to give structual viscosity to the system of the shampoo composition, thereby preventing settlement of Mept compounds. Such methods cannot avoid limitations to surfactants to be incorporated into a shampoo base or viscosity of the shampoo base.

Preparation of hair rinse compositions or hair conditioning compositions is also accompanied by the limitation to viscosity of the composition in the case where fine particulate Mept compounds are incorpoarted into the compositions. Namely, the bases are limited to a highly viscous ones such as of emulsion system or gel.

SUMMARY OF THE INVENTION

In view of the above, the present inventors have further made an earnest study in order to overcome such problems, and have found that when fine particulate Mept compounds are dispersed in water by aid of a specific dispersant, the resulting suspension is excellent in that it is highly stable under the ordinary storage conditions, is superior in resistivity to salts, and, even frozen, can be restored to the state before frozen if only heated to melt. Surprisingly, it was also found that when thus prepapred aqueous dispersion of fine particulate Mept compounds was incorporated into a base of hair treatment compositions such as shampooes, hair rinses and hair lotions, the dispersion state of fine particulate Mept compounds could be maintained stably being free from limitations to storage conditions or to surfactants to be used in combination.

Accordingly, this invention consists of a first invention which relates to an antimicrobial suspension characterized by comprising a fine particulate polyvalent metal salt of 2-mercaptopyridine-N-oxide having a size distribution in which particles having a size below 0.2 micron are contained in amounts not smaller than 50 wt % and a dispersant selected from the group consisting of (A), (B) and (C):

(A) A polyglycol/polyamine condensation polymer or a polyglycol/polyamine/alkyl or alkyleneamine condensation polymer;

(B) At least one water-soluble polymer compound selected from the group consisting of hydroxyalkylcelluloses and partly quaternarized products thereof, and at least one non-ionic surfactant;

(C) At least one cationic polymer compound and at least one inorganic salt, and a second invention which relates to an antimicrobial hair treatment composition in which a hair treatment base thereof is incorporated with the antimicrobial suspension.

BRIEF DESCRIPTION OF THE DRAWING

The sole FIGURE is a graph showing relation between particle size of fine particulate Zpt and Amizet 5C.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The Mept compounds according to the invention are represented by the following general formula: ##STR1## wherein M represents a polyvalent metal atom and x represents the atomic value of M.

Examples of the polyvalent metal atom, M includes magnesium, barium, strontium, zinc, cadmium, tin and zirconium. Of these, zinc salt of 2-mercaptopyridine-N-oxide is preferred.

The fine particulate Mept compounds to be used in the prssent invention have a size distribution in which not smaller than 50 wt % of the particles have a size of 0.2 micron or less. Preferably, the fine particulate metal salts have such a size distribution that particles having a size ranging from 0.5 to 1.0 micron are contained in amounts not larger than 15wt %, and particles having a size not smaller than 1.0 micron are contained 2 wt % or less. The fine particulate Mept compounds having such size dittribution can be prepared by any of the following methods:

(1) Method of utilizing a shear force of rigid body media such as glass beads having a particle size not larger than 0.5 mm, with which Mept compounds are agitated thereby obtaining fine powder (Japanese patent Applicaiion No. 58-122845).

(2) Method of reacting a monovalent water-soluble salt of 2-mercaptopyridine-N-oxide and an water-soluble polyvalent metal salt in the presence of an water-soluble compound having a basic nitrogen atom in a molecular thereof under hhe condition of pH 3 to 7, or optionally, further proceeding this reaction in the presence of a water-soluble compound having hydroxy group under a temperature of not higher than 0.degree. C. (Japanese Patent Application No. 58-122846).

(3) Method of stirring a dispersion of Mept compounds together with rigid body media having a particle size not larger than 0.2 mm in the presence of a salt of (metha)acrylic acid-stylene sulfonic acid copolymer having an average molecular weight of 10,000 to 1,000,000 (Japanese patent Application No. 59-82690)

Among the dispersants usable in the present invention, the condensation polymers (A) are curable condensation products obtainable from firstly reacting a polyamine compound having from 2 to 10 carbon atoms with an ether of polyoxyalkylene glycol having a terminal halogen or hydroxyl group and having from 2 to 4 carbon aooms in an alkylene unit thereof, further reacting the resulting polyamine reaction product having at least one hydrogen atom joined to a nitrogen atom with a bifunctional aliphatic compound aaving a functional group selected from the group consisting of epoxide and alpha-halo-beta-hydroxyalkyl. Alternatively, the thus obtained condnsation product may further be reacted with amines having saturated or unsaturated hydrocarbon group having 10 to 24 carbon atoms thereby obtaining a curable condensation product.

Preferable condensation polyeers are mentioned below.

(I) Reaction product of dipropylenetriamine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000 and epichlorohydrin.

(II) Reaction product of dipropylenetriamine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000, coconut oil fatty acid amine or beef tallow fatty acid amine and epichlorohydrin.

(III) Reaction product of dipropylenetriamine and bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600.

(IV) Reaction product of dipropylenetriamine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600, coconut oil fatty acid amine or beef tallow fatty acid amine.

(V) Reaction product of dipropylenetriamine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000 and bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600.

(VI) Reaction product of dipropylenetriamine, bisclorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600 and coconut oil fatty acid amine or beef tallow fatty acid amine.

(VII) Reaction product of diethylenetriamine, ethoxylated ethylene chlorohydrin and epichlorohydrin.

(VIII) Reaction product of diethylenetriamine, ethoxylated ethylene chlorohydrin, epichlorohydrin, and coconut oil fatty acid amine or beef tallow fatty acid amine.

(IX) Reaction product of dipropylenetriamine, ethoxylated glycerine chlorohydrin ether and epichlorohydrin.

(X) Reaction product of dipropylenetriamine, ethoxylated glycerine chlorohydrin ether, epichlorohydrin and coconut oil fatty acid amine or beef tallow fatty acid amine.

(XI) Reaction product of triethylenetetramine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000 and bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600.

(XII) Reaction product of triethylenetetramine, biscchlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 1,000, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 600 and coconut oil fatty acid amine or beef tallow fatty acid amine.

(XIII) Reaction product of dipropylenetriamine and bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 200.

(XIV) Reaction product of dipropylenetriamine, bischlorohydrin ether of polyoxyethylene glycol having an average molecular weight of about 200 and coconut oil fatty acid amine or beef tallow fatty acid amine.

The ratio of the chlorine atoms to the hydrogen atoms of amino group in the reaction products of (I) to (XIV) is preferred to be in the range of 4:5 to 7:5.

Typical and preferable example of the condensation polymers is the product commercially sold under the trade name of Polyquart H from Henkel Co., Ltd., as a 50% aqueous solution.

Condensation polymers (A) are preferably incorporated in an amount of 1/100 to 10 times, more preferably 1/100 to 5 times of the fine particulate Mept compounds on the weight basis, and the balance is preferably an aqueous medium such as water or lower alcohol/water.

In the case where dispersant (A) is used, fine particulate Mept compounds should be incorporated in an amount of 0.0015 to 60%, and more preferably 0.1 to 50% of the total amount.

Examples of hydroxyalkyl celluloses of dispersant (B) of the invention include hydroxyethyl cellulose, hydroxypropyl cellulose and the like. Cationic cellulose derivatives obtainable by quaternarizing the hydroxyalkyl celluloses are preferably those represented by the following formula: ##STR2## wherein A.sub.1 represents a residue of anhydroglucose unit, l represents an integer of from 50 to 20,000, and each R.sub.1 represents a substitutional group represented by the following general formula (2): ##STR3## wherein R', R": alkylene group having 2 or 3 carbon atoms,

m: integer of from 0 to 10

n: integer of from 0 to 3

p: integer of from 0 to 10

R"': alkylene group or hydroxyalkylene group having 1 to 3 carbon group,

R'.sub.1, R'.sub.2, R'.sub.3 : same or different with each other and independently represent alkyl having up to 10 carbon atoms, aryl or aralkyl group, and may form a heterocyclic ring containing a nitrogen atom of the formula (2).

x: anion (chlorine, bromine, iodine, sulfuric acid, sulfonic acid, methylsulfuric acid, phosphoric acid, nitric acid etc.)

The cation substitution degree of the cationic celluloses preferably ranges from 0.01 to 1, in other words, average value of n per anhydroglucose unit is preferably 0.01 to 1, and more preferably, 0.02 to 0.5. Average value of m+p ranges from 1 to 3. Substiuution degree of 0.01 or less is insufficient. On the other hand, that of 1 or more is objectionable in view of the yield of the reaction. Molecular weight of the cationic celluloses usable in the present invention ranges from about 100,000 to 300,000.

Specific examples of the non-ionic surfactants of dispersant (B) are mentioned below.

(1) Polyoxyethylene alkyl or alkenyl ethers having an alkyl or alkenyl group having 10 to 20 carbon atoms on average and polyoxyethylene group having 1 to 20 units of ethylene oxide.

(2) Polyoxyethylene alkylphenyl ethers having an alkyl group having 6 to 12 carbonaatoms on average and polyoxyethylene group having 1 to 20 units of ethylene oxide.

(3) Polyoxypropylene alkyl or alkenyl ethers having an alkyl or alkenyl group having 10 to 20 carbon atoms on average and polyoxyprolylene group having 1 to 20 units of propylene oxide.

(4) Polyoxybutylene alkyl or alkenyl ethers having an alkyl or alkenyl group having 10 to 00 carbon atoms on average and polyoxybutylene group having 1 to 20 units of butylene oxide.

(5) Nonionic surface active agents having an alkyl or alkenyl group having 10 to 20 carbon atoms on average and added with 1 to 30 moles, in total, of ethylene oxide and propylene oxide or ethylene oxide and butylene oxide (arratio of ethylene oxide and propylene oxide or butylene oxide is in the range of 0.1/9.9 to 9.9/0.1).

(6) Higher fatty acid alkanolamides of the following formula or alkylene oxide adducts thereof ##STR4## wherein R.sub.2 represents an alkyl or alkenyl group having 7 to 21 carbon atoms, R3 is a hydrogen atom or a methyl group, n.sub.2 is an integer of 1 to 20, and m3 is an integer of 0 to 20, and hardened castor oil.

Examples of the cationic polymer compounds of dispersant (C) in the invention include the following compounds (a), (b) and (c), and they are used solely or in combination of two or more.

(a) Copolymer-type cationic polymer compounds of dimethyldiallylammonium halide and acryl amide: ##STR5## wherein R.sub.25 and R.sub.26 are the same or different with each other and independently represent a hydrogen atom or methyl, x represents a halogen atom, and l and m.sub.4 are such integers that the sum of l and m.sub.4 ranges from 180 to 2,000.

Although the compounds are represented by formula (a) here, they are not necesssarily a block-type copolymer, and arrangmment of the monomers may be arbitrary changed. Of these, compounds in which x is chlorine are sold under the tradename "Merquat 550" (Merck & Co., Inc./ U.S.A.)

(b) Polycondensation products of adipic acid and dialkylaminohydroxppropyl diethylenetriamine represented by the following formula and quaternarized products thereof: ##STR6## wherein R.sub.27 and R.sub.28 are the same or different with each other and independently represent an alkyl group having from 1 to 18 carbon atoms and n.sub.4 represents such integer that will give the molecular weight ranging from332 to 100,000.

Of these, those whose R.sub.27 and R.sub.28 are methyl are available from Sandoz Co., Ltd. under the tradename of "Cartaretin F".

(c) Copolymers represented by the following formula and quaternarized products thereof: ##STR7## wherein R.sub.29 represents a hydrogen atom, methyl group or ethyl group, Z represents an oxygen atom or a group --NH--, R.sub.30 represents an alkylene group having 1 to 4 carbon atoms, R.sub.31 and R.sub.32 are the same or differnnt with each other and independently represent an alkyl group having 1 to 18 carbon atoms, and p and q are such integers that will give a molecular weight ranging from 1,000 to 5,000,000.

Although the compounds are represented by the above formula, they are not necessarily a block-type copolymer, and arrangement of the monomers may be changed arbitrarily. Of these, compounds in which Z is oxygen, R.sub.29 is methyl, R.sub.30 is ethylene, R.sub.31 and R.sub.32 are methyl and quaternarized by (C.sub.2 H.sub.5).sub.2 SO.sub.4 are available from GAF Corporation under the tradenames of "Gafqurt 755" and "Gafqurt 734".

The inorganic salts sable as a member of dispersant (C) include alkali metal salts, alkaline earth metal salts or aluminum salts of an inorganic acid such as chloric acid, sulfuric acid, nitric acid and the like. Of these inorganic salts are preferred potassium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, potassium nitrate, sodium nitrate, magnesium nitrate, calcium nitrate, aluminum nitrate, potassium chloride, sodium chloride, magnesium chloride, calcium chloride, aluminum chloride, potassium carbonate, sodium carbonate, aluminum carbonate. Among them, especially preferred ones are sodium sulfate, potassium nitrate, sodium nitrate, potassium chloride and sodium chloride.

The antimicrobial suspensions of the invention may be prepared according to conventional method by adding a powder of fine particulate Mept compounds or suspension thereof to a solution of the above-mentioned dispersants, but preferably be prepared by the following process.

Namely, the suspensioniis prepared by a method in which a powder of fine particulate Mept compounds is added to a 50% solution of dispersant (A) or a diluted solution thereof and agitated to give a uniform mixture, or by a method in which a dispersion of fine particulate Mept compounds is added to a 50% solution of dispersant (A) or a diluted solution thereof under agitation and further agitated to obtain a uniform mixture. The mixing is carried out using ordinary mixers such as propeller agitator apparatus, homogenizer mixers, sand mills and the like.

When dispersant (B) is used, the following four ingredients are processed as described below.

(1) 1 to 10% (as effective amount) of fine particulate Mept compounds,

(2) Water-soluble polymer compound in an amount of 5 wt % or more of the fine particulate Mept compounds,

(3) Non-ionic surfactant in an amount of 5 wt % or more of the water-soluble polymer compound,

(4) Inon-exchanged water as balance. (First, 2) is dissolved in (4), then added with (3), followed by further addition of (1) under agitation until uniform mixture is obtained. Alternatively, (2) is dissolved in (4), then added with (1) and mixed well, followed by further addition of (3) under agitation until uniform suspension is obtained. The mixing apparatus usable in the process are ordinary ones as described before.

Further, in case where dispersant (C) is used for preparing an antimicrobial suspension, an aqueous solution comprising 0.1 to 60 wt %, preferably 1 to 50 wt % of a cationic polymer compound and 0.1 to 25 wt %, preferably 1 to 25 wt % of an inorganic salt should firstly be prepared. Examples of solvents are water or mixture of water and lower alcohol. Into the thus obtained aqueous solution, a dispersion comprising 0.1 to 60 wt %, preferably 0.1 to 50 wt % of fine particulate Mept compounds is added and agitated until uniform mixture is obtained. The mixing is carried out by a similar apparatus described before. The thus obtained antimicrobial suspensions can be used as it is. Optionally, they may be subjected to filtration under pressure, by which step, Mept particle having improved surface are obtainable.

Examples of antimicrobial hair treatment compositions according to the second invention include compositions for shampooes, hair rinses, hair lotions and the like. These compositions are prepared by incorporating the above described antimicrobial suspensions into a hair treatment bas under agitation and uniformly mixing them. The antimicrobial suspension should be incorporated in such an amount that the amount of fine particulate Mept compounds are 0.01 to 10 wt %, especially 0.05 to 5 wt % of the total composition.

The bases for hair treatments are those ordinarily used for these purposes. Among the hair treatment compositions, shampoo or hair rinse compositions are preferable in the practice of the invention. The bases for shampooes include anionic surfactants, amphoteric surfactants, cationic surfactants and mixtures thereof. Specific examples of these surfactants are mentioned below.

Anionic surfactants:

(1) Linear or branched alkylbenzenesulfonates having an alkyl group having 10 to 16 carbon atoms on average.

(2) Polyoxyalkylene alkyl ether sulfates having a linear or branched alkyl group having 8 to 20 carbon atoms on average and added with 0.5 to 8 moles of ethylene oxide and/or propylene oxide in one molecule thereof on average.

(3) Alkylsulfates having a linear or branched alkyl group having 10 to 20 carbon atoms on average.

(4) Olefinsulfonates having 10 to 20 carbon atoms in one molecule thereof on average.

(5) Alkanesulfonates having 10 to 20 carbon atoms in one molecule thereof on average.

(6) Fatty acid salts having a linear or branched, saturated or unsaturated hydrocarbon chain having 10 to 20 carbon atoms on average.

(7) Alkylethoxycarboxylates having a linear or branched alkyl group having 10 to 20 carbon atoms and added with 0.5 to 8 moles of ethylene oxide in one molecule thereof on average.

(8) Alkyl or alkenylsuccinates having an alkyl or alkenyl group having 6 to 20 carbon atoms on average and partially neutralized salts thereof.

(9) Phosphate aciive agents of the formula ##STR8## in which A represents ##STR9## (in which R.sub.1 represents a linear or branched, saturated or unsaturated hydrocarbon group, R.sub.2 represents a hydrogen atom or a methyl group, m is an integer of from 0 to 6, and n is an integer of 1 to 6), B represents --OX.sub.2 or A, and X.sub.1 and X.sub.2 independently represent a hydrogen atom or counter ion.

(10) Amino acid surface active agent of the formulae ##STR10## in which R.sub.3 represents an alkyl or alkenyl group having 7 to 21 carbon atoms, X.sub.3, X.sub.4 and X.sub.5 independently represent a hydrogen atom or counter ion.

(11) Acylated polypeptide surface active agents of the formula ##STR11## in which R.sub.4 represents an alkyl or alkenyl group having 7 to 21 carbon atoms, R.sub.5, R.sub.6 and R.sub.7 independently represent a side chain of an amino acid, n.sub.1 is an integer of 1 to 6, and X.sub.6 represents a hydrogen atom or counter ion.

The counter ions represented by X.sub.1 to X.sub.6 of these anionic surfactants generally include ions of alkali metals such as sodium, potassium and the like; alkaline earth metals such as magnesium; ammonium ion and alkanolamine bases having 1 to 3 alkanol groups having 2 or 3 carbon atoms such as, for example, monoethanolamine, diethanolamine, triethanolamine, triisopropanolamine and the like.

Amphoteric surfactants:

(12) Alkylamine oxides (I) and amidoamine oxides (II) of the following formulae ##STR12## in which R.sub.8 represents an alkyl or alkenyl group having 10 to 20 carbon atoms, R.sub.9 and R.sub.10 independently represent an alkyl group having 1 to 3 carbon atoms, and m.sub.1 is an integer of 1 to 4.

(13) Alkyl or sulfobetaines (III) and amido or amidosulfobetaines (IV) of the following formulae ##STR13## in which R.sub.11 and R.sub.12 independently represent an alkyl group having 1 to 4 carbon atoms, m.sub.2 is an integer of 1 to 3, X.sub.7 represents a COO.sup..crclbar. or -SO.sub.3.sup.63 group, m.sub.1 and R.sub.8 have the same meanings as defined before, respectively.

(14) Imidazoline amphoteric surface active agents of the following formula ##STR14## in which R.sub.13 is an aliphatic acid residue having 10 to 20 carbon atoms on the average, R.sub.14 represents sodium, hydrogen or --CH.sub.2 COOM.sub.2, Z.sub.1 represents ##STR15## in which M.sub.2 represents sodium, hydrogen or an organic base, X.sub.8 represents a hydroxyl group, an acidic salt, an anionic surface active sulfate or a sulfated product.

(15) Amidoamine amphoteric surface active agents of the formula ##STR16## in which R.sub.15 represents an alkyl or alkenyl group having 6 20 carbon atoms, R.sub.16 represents hydrogen, --C.sub.2 H.sub.4 OH or --C.sub.2 H.sub.4 OC.sub.2 H.sub.4 COOX.sub.9, R.sub.17 represents --C.sub.2 H.sub.4 OH, --C.sub.2 H.sub.4 OC.sub.2 H.sub.4 COOX.sub.9 or --C.sub.2 H.sub.4 COOX.sub.9, and R.sub.18 represents hydrogen or --C.sub.2 H.sub.4 COOX.sub.9, X.sub.9 represents hydrogen, alkali metal, ammonium or organic ammonium. Cationic surfactants: ##STR17## in which at least one of R.sub.20, R.sub.21, R.sub.22 and R.sub.23 represents an alkyl or alkenyl group having 8 to 24 carbon atoms and the other represent an alkyl group having 1 to 5 carbon atoms, and X' represents a halogen atom. ##STR18## in which R.sub.20, R.sub.21, R.sub.22 and X' have the same meanings as defined before, respectively. ##STR19## in which R.sub.20, R.sub.21 and X' have the same meanings as defined before, respectively, n.sub.3 is an integer of 1 to 20, and R.sub.24 represents an alkylene group having 2 to 3 carbon atoms.

It is to be noted that dispersant (B) requires a non-ionic suffactant as an essential component thereof, but when other dispersants are used, non-ionic surfactants may be incorporated as an arbitrary ingredient. Examples of the non-ionic surfactants include, aside from the before-mentioned polyoxyethylene alkyl or alkenyl ethers, polyoxyethylene alkylphenyl ethers, polyoxypropylene alkyl or alkenyl ethers, polyoxybutylene alkyl or alkenyl ethers, non-ionic surfactants obtainable by adding propyleneoxide or butylene oxide to ethylene oxide, and higher fatty acid alkanolamides or alkylene oxide adducts thereof, the following compounds are mentioned.

(19) Sucrose fatty acid esters obtainable from fatty acid having 10 to 20 carbon atoms on average and sucrose,

(20) Fatty acid glycerine monoester obtainable from fatty acid having 10 to 20 carbon atoms on average and glycerine.

Of these suractants, agents (1), (2), (3), (4), (5), (6), (11), (I) and (II) of (12), (13), (14), (15), polyoxyethylene alkyl or alkenyl ethers and higher fatty acid alkanolamides or alkyleneoxide adducts thereof are preferred. These surfactants may be used singly or in combination. Suitable amount of the surfactants is, for example, in the range not less than 5 wt %, preferably from 10 to 40 wt % in total, of the composition.

The antimicrobial hair treatment compositions may further comprise, aside from the above-described essential ingredients, any arbitrary ingredients ordinarily used for these purposes. Examples of such arbitrary ingredients include: solubilizers such as propylene glycol, glycerine, urea and the like; viscosity modifiers such as ethyl alcohol, isopropyl alcohol, methyl cellulose, higher alcohols and the like; preservatives; antiseborreheic agents; keratin-soluble or swelling substances such as sulfur, salicylic acid and enzymes; deodorants; pearling agents; lotionizing agents; perfumes; colorants; UV absorbers; antioxidants; preservatives and the like.

Action:

The function of the dispersants to be used in the present invention is not clear but it is considered that the dispersants make the particle surface of the fine particulate Mept compounds improved, thereby aggregation of the particles is prevented.

Effects of the Invention:

Several shampooes and hair rinses containing the Mept compounds are put on the market. However, in order to stably incorporate the Mept compounds into shampoo or hair rinse compositions, it is unavoidable to make them highly viscous or to add specific types of polymers or clay minerals. This leads to the disadvantage that the compositions become poor in performance, e.g. with shampooes, the foaming performance becomes poor with objectionable texture of the hair after shampooing.

Different from conventional method of modifying the viscosity of dispersion medium for improving the dispersion stability of Mept compounds, the inventive method utilizes fine particulate Mept compounds, thereby obtaining an antimicrobial suspension of very stable dispersion. Antimicrobial hair treatment compositions which incorporate fine particulate Mept compounds are excellent in storage stabllity and in feel on use.