JP3390222B2 - Polymer latex and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel epoxy-modified block copolymer latex and a method for producing the latex. More particularly, it relates to the latex of an epoxy-modified block copolymer having a functional group and having improved mechanical stability and adhesiveness. Furthermore, the present invention relates to an effective method for producing the polymer latex.

[0002]

2. Description of the Related Art Conventionally, most polymer latexes have been produced by an emulsion polymerization method and have been put to practical use. On the other hand, due to the progress of polymerization technology in recent years, a polymer having a characteristic structure and physical properties that cannot be obtained by an emulsion polymerization method,
For example, styrene-butadiene block copolymers have been introduced.

When these polymers are used in conventional fields of use of latex such as paints and adhesives, they have often been put to practical use as a solution of a volatile organic solvent, but pollution and organic solvents have been used. Due to problems such as poisoning, it is not preferable to use an organic solvent for the end use of the product. Therefore, latex of aqueous dispersion has been attracting attention.

A general method for producing a latex of a polymer having characteristic properties which cannot be obtained by these emulsion polymerization methods is to dissolve a polymer solution or solid polymer in a suitable organic solvent. This is a method in which an emulsifier and water are added to the above solution to emulsify, and the solvent is removed from the obtained emulsion to obtain a latex. If the polymer content of the latex thus obtained is low, it may be concentrated by operations such as creaming, centrifugation or water evaporation. However, when trying to obtain a polymer latex by such a method, when removing the solvent from the emulsion, aggregation or precipitation of polymer particles occurs due to contact with a heating part or the like, The mechanical stability of the latex is remarkably inferior to that of the latex obtained by emulsion polymerization. In particular, the poor mechanical stability makes the concentration operation by centrifugation impossible, and causes many difficult problems when the latex is transported and used for the final use.

That is, when a large mechanical shearing force is applied to the thus obtained latex having a relatively poor mechanical stability, the latex is partially or, in a remarkable case, entirely contacted and fused between the latex particles, and It may form an aggregate and lose the original function of the latex. This tendency is remarkable especially when mechanical shearing force is applied at high temperature. Then, the manufacturing method of these polymer latex which can solve the above-mentioned problem was desired.

[0006]

The present invention provides a novel epoxy-modified vinyl aromatic compound-conjugated diene compound block copolymer latex having good mechanical stability and improved adhesion. It is in.

[0007]

The present inventors have arrived at the present invention as a result of studies to solve the above problems. That is, the first aspect of the present invention is that the double bond of the unsaturated carbon of the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer is hydroperoxidized in an inert solvent.
For reacting with epoxidizing agents such as ids and peracids
The present invention relates to a latex of an epoxy-modified block polymer which is more epoxidized, and a second aspect of the present invention relates to a method for producing the epoxy-modified block copolymer, wherein an organic solvent solution of the epoxy-modified block polymer is treated with water and an emulsifier. And a step of removing an organic solvent from the emulsion obtained in (1) above, and a step of emulsifying the epoxy modified block copolymer latex.

The present invention will be described in detail below.

Examples of the vinyl aromatic compound constituting the block polymer used in the present invention include styrene and α
-Methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene,
1 or 2 of 1,1-diphenylstyrene
One or more kinds can be selected, and styrene is preferable.

Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene,
2,3-dimethyl-1,3-butadiene, piperylene,
3-butyl-1,3-octadiene, phenyl-1,3
-One kind or two or more kinds are selected from butadiene and the like, and among them, butadiene, isoprene and a combination thereof are preferable.

The block copolymer referred to herein is a block copolymer composed of a polymer block A mainly containing a vinyl aromatic compound and a polymer block B mainly containing a conjugated diene compound. The copolymerization ratio of the group compound and the conjugated diene compound is 5/95 to 10/90, and the polymerization ratio of 10/90 to 60/40 is particularly preferable.

The block copolymer used in the present invention has a number average molecular weight of 5,000 to 600,000, preferably 1.
The molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] is 10 or less. The molecular structure of the block polymer may be linear, branched, radial or any combination thereof. For example, A-B-A, B -A-B-A, (A-B-) 4 S
It is a vinyl aromatic compound-conjugated diene compound block polymer having a structure such as i, A-B-A-B-A. Further, the unsaturated bond of the conjugated diene compound of the block polymer may be partially hydrogenated.

As the method for producing the block polymer used in the present invention, any method can be used as long as it has the above-mentioned structure. For example, Japanese Patent Publication No. 40-2
No. 3798, Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 46-
A vinyl aromatic compound-conjugated diene compound block copolymer can be synthesized in an inert solvent using a lithium catalyst or the like by the method described in Japanese Patent Publication No. 32415 and Japanese Patent Publication No. 56-28925. Furthermore, Japanese Examined Japanese Patent Publication No. 42-87
A part which is hydrogenated in the presence of a hydrogenation catalyst in an inert solvent according to the method described in JP-B No. 04, JP-B-43-6636, or JP-A-59-133203 and used for the present invention. It is possible to synthesize a block copolymer that has been hydrogenated.

In the present invention, the epoxy-modified block copolymer used in the present invention is obtained by epoxidizing the above block copolymer.

The epoxy-modified block copolymer in the present invention can be obtained by reacting the above block copolymer with an epoxidizing agent such as hydroperoxides and peracids in an inert solvent. Examples of peracids include formic acid, peracetic acid, perbenzoic acid, and trifluoroperacetic acid. Of these, peracetic acid is a preferred epoxidizing agent because it is industrially produced in large quantities, is inexpensively available, and has high stability.

Hydroperoxides include hydrogen peroxide, tertiary butyl hydroperoxide, cumene peroxide and the like.

A catalyst may be used in the epoxidation, if necessary. For example, in the case of peracid, an alkali such as sodium carbonate or an acid such as sulfuric acid can be used as a catalyst. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda with hydrogen peroxide, an organic acid with hydrogen peroxide, or molybdenum hexacarbonyl with tert-butyl hydroperoxide. You can

There is no strict restriction on the amount of epoxidizing agent, and the optimum amount in each case is variable, such as the particular epoxidizing agent used, the desired degree of epoxidation, the individual block copolymer used, etc. Determined by factors. As the inert solvent, it is possible to use it for the purpose of reducing the viscosity of the raw material and stabilizing it by diluting the epoxidizing agent. In the case of peracetic acid, aromatic compounds, ethers, esters, etc. may be used. it can. Particularly preferred solvents are hexane, cyclohexane, toluene, benzene, ethyl acetate, carbon tetrachloride, chloroform.

There are no strict restrictions on the epoxidation reaction conditions. The reaction temperature range that can be used depends on the reactivity of the epoxidizing agent used. For example, peracetic acid is 0
The temperature is preferably 70 ° C, the reaction is slow at 0 ° C or lower, and the decomposition of peracetic acid occurs at higher than 70 ° C. In the tertiary butyl hydroperoxide / molybdenum dioxide diacetylacetonate system, which is an example of hydroperoxide, the temperature is preferably 20 ° C to 150 ° C for the same reason. No special manipulation of the reaction mixture is necessary, for example 2 to 10
Stir for hours.

The degree of epoxidation (expressed by epoxy equivalent) of the epoxy-modified block polymer in the present invention is 0.1
Titrate with specified hydrobromic acid and calculate by the following formula.

[0021]

[Chemical 1] The epoxy equivalent of the epoxy-modified block polymer in the present invention is 140 to 2700, and particularly preferably 2
It is necessary that it is from 00 to 2000 for the adhesion and mechanical stability of the latex film.

Next, the method for producing the latex of the present invention will be described.

[Production Method] In the step (1) of the method for producing a latex of the present invention (claim 4), the modified block copolymer is used as an organic solvent solution, and this solution is mixed with water or water. And emulsifier are added and emulsification is performed using an emulsifying machine. The organic solvent used is not particularly limited as long as it is substantially insoluble in water. Preferred organic solvents that are usually used are aliphatic, alicyclic compounds having a boiling point of 180 ° C. or lower,
Aromatic hydrocarbons, halides thereof, ethers, etc., and two or more kinds of them may be mixed and used.

The concentration of the polymer or copolymer solution is not particularly limited, but it is usually used in the range of 5% by weight to 60% by weight, preferably 10% by weight to 50% by weight.
Is. If it is less than 5% by weight, the productivity will be poor, and if it exceeds 60% by weight, the viscosity of the solution will remarkably increase, making it difficult to prepare the solution itself and making the emulsification operation difficult.

For the purpose of improving the emulsifying action and the mechanical stability of the latex, an emulsifier, preferably one or more anionic, nonionic or anion-nonionic surfactant is added. Emulsify. In order to carry out the treatment more effectively, it is preferable to use (a) one or more anionic surfactants and (b) one or more nonionic or anion-nonionic surfactants in combination. The use amount of these is small compared with the amount conventionally used in the method for producing a latex of this type, and is effective for emulsification and improvement of mechanical stability of the latex. The amount of each used is 0.05 to 10 parts by weight with respect to 100 parts by weight of the modified block copolymer, foaming in the solvent removal step,
In order to avoid discoloration of the emulsifier, film strength of the latex, deterioration of adhesiveness, etc. during long-term storage, 0.05 to 5 parts by weight is preferable, and the total amount of (a) and (b) is 5 parts by weight or less. It can be said that it is more preferable to be present.

The anionic surfactant used as the component (a) is a higher fatty acid salt, a rosin acid salt, a dialkylsulfosuccinic acid salt, an alkylbenzenesulfonic acid salt, a mono- or dialkylnaphthalenesulfonic acid salt, and the like. Typical examples are sodium and potassium salts of stearic acid, oleic acid, etc., natural rosin acid or sodium or potassium salts of disproportionated or hydrogenated rosin acid modified with natural rosin acid, sodium dibutylsulfosuccinate, dioctyl. Examples thereof include sodium sulfosuccinate, sodium dodecylbenzene sulfonate, and sodium dioctylnaphthalene sulfonate.

The component (b) of the nonionic or anionic-nonionic surfactant is represented by the general formula:

[Chemical 2] <However, R1 is an alkyl group having 8 to 18 carbon atoms, R1
2 is an alkyl group having 8 to 18 carbon atoms, an alkylphenyl group having an alkyl group having 8 to 12 carbon atoms, or an aromatic hydrocarbon group having 2 or more phenyl groups, R3
Is an alkylene group having 2 to 5 carbon atoms, X is hydrogen or an alkali metal, m is an integer of 3 to 50, and the one represented by (A) is polyoxyethylene stearin. Examples of the acid ester, polyoxyethylene lauryl acid ester and the like represented by (B) include polyoxyethylene palmityl ether, polyoxyethylene octyl phenyl ether,
Representative examples thereof include polyoxyethylene nonyl phenyl ether and polyoxyethylene benzyl phenyl ether. Further, as the one represented by (C), sodium nonylphenoxypolyoxyethylene sulfate and the like, as the one represented by (D), polyoxyethylene nonylphenyl ether phosphate, polyoxyethylene lauryl ether phosphate diester, and the like. Sodium salt etc. are mentioned.

The above various emulsifiers are dissolved in the polymer solution or water before emulsification. As the anionic surfactant, a preferred method of adding a higher fatty acid salt or rosin acid salt is to add these salts to the polymer solution side of the higher fatty acid or rosin acid which is an acid, and sodium hydroxide or water which is a base. That is, potassium oxide, ammonia, and triethanolamine are separately added to the water side to form a salt during emulsification. The emulsifying machine used for emulsification does not need to be limited to a specific type, and any known emulsifying machine may be used as long as the emulsifying ability is sufficiently strong. Examples of emulsifiers that can be used include homomixers, homogenizers,
There are a disper mill, a colloid mill, etc., and if necessary, two kinds of emulsifying machines can be combined.

Next, as a method of removing the solvent from the emulsion in the step of claim 4 (2), a method of heating by distillation from a jacket in a steam kettle and a method of steam distillation by directly blowing steam are used. Any method such as a method or a method using a centrifugal thin film evaporator may be used. It is also possible to produce a latex with a small amount of solvent left behind by controlling the removal of the solvent if desired.

The emulsifier used for emulsification has a relatively small foaming property, but it may be accompanied by some foaming depending on the combination, type and amount. At this time, this can be prevented by adding a small amount of a known antifoaming agent to the emulsion to be supplied or directly to the evaporator.
A preferred defoaming agent is one whose main component is a lower alcohol, a mineral oil, an organic polar compound, a polyalkylene glycol, a surfactant having a low HLB value, a silicone resin, an organic silicone oil, or the like.

The latex thus obtained usually has a solid content concentration of about 5 to 65% by weight, but those having a low solid content concentration may be concentrated if necessary. As a method of making concentrated latex,
There are creaming, centrifugal separation, water evaporation, and the like. Particularly, concentration by a centrifuge is efficient, and reproducibility is excellent, so that it is a preferable method. By carrying out the present invention, aggregation and precipitation of latex particles are extremely small in any concentration method, and the concentration can be easily performed.

Further, in the present invention, an oil-extendable or oil-soluble plasticizer or softening agent is added to the solution of the modified block copolymer,
It is also possible to emulsify by adding a thermoplastic resin, an oligomer, a stabilizer and a colorant. Examples thereof include synthetic ester plasticizers such as dioctyl phthalate and dioctyl sebacate, paraffin-based, aroma-based, naphthene-based process oils, terpene resins, coumarone resins, low molecular weight styrene resins, polystyrene, polyolefins, various oligomers. And so on.

These may be dissolved in an organic solvent after being mixed with the modified block copolymer, or may be mixed with separately dissolved solutions.

Further, each of the above-mentioned additives can be added as it is or as an aqueous solution or latex after the modified block copolymer of the present invention is obtained.

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. In the following description, parts and% mean parts by weight and% by weight, respectively.

<< Preparation of Epoxy-Modified Block Copolymer >><Preparation Example 1> A polystyrene / polybutadiene / polystyrene block copolymer [Japan Synthetic Rubber ( Co., Ltd., trade name: TR2000] 300 g and toluene 1500 g were charged and dissolved. 30% of peracetic acid
169 g of a% ethyl acetate solution was continuously added dropwise, and the mixture was stirred at 40
The epoxidation reaction was carried out at ℃ for 3 hours. The reaction solution was returned to room temperature and washed with water to reduce the acid value to 1 or less (30% by weight solution of epoxy-modified block copolymer in toluene-ethyl acetate; A. Epoxy equivalent of polymer)
470).

<Adjustment Example 2> A block copolymer of polystyrene-polybutadiene-polystyrene in a jacketed reactor equipped with a stirrer, a reflux condenser, and a thermometer [Shell Chemical Co., Ltd., trade name: Califlex D1122].
300 g and 1500 g of cyclohexane were charged and dissolved. Then, 177 g of a 30 wt% ethyl acetate solution of peracetic acid
Was continuously added dropwise, and the epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring. The acid value was adjusted to 1 or less by returning the reaction solution to room temperature and washing with water (28% by weight cyclohexane-ethyl acetate solution of epoxy-modified block copolymer; B
The epoxy equivalent of the polymer is 448).

<Preparation Example 3> A block reactor of polystyrene-polyisoprene-polystyrene was added to a jacketed reactor equipped with a stirrer, a reflux condenser, and a thermometer [Shell Chemical Co., Ltd., trade name: Califlex TR111.
1] 300 g and cyclohexane 1500 g were charged and dissolved. Then, a 30 wt% ethyl acetate solution 222 of peracetic acid
g was continuously added dropwise, and the epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring.

The acid value was reduced to 1 or less by returning the reaction solution to room temperature and washing with water (25% by weight cyclohexane-ethyl acetate solution of epoxy-modified block copolymer; C, epoxy equivalent of polymer: 362). .

<Preparation Example 4> A polystyrene-polyisoprene-polystyrene block copolymer [Kuraray Co., Ltd., vinyl structure polyisoprene block] was placed in a jacketed reactor equipped with a stirrer, a reflux condenser and a thermometer. Having, product name: VS-1] 300 g, toluene 1
500 g was charged and dissolved. Then 30% by weight of peracetic acid
Continuously add 222 g of ethyl acetate solution and stir at 40 ° C.
The epoxidation reaction was carried out for 4 hours.

The reaction solution was returned to room temperature and washed with water to reduce the acid value to 1 or less (22% by weight solution of epoxy modified block copolymer in toluene-ethyl acetate; D,
Epoxy equivalent of polymer 375).

<Adjustment Example 5> In a reactor equipped with a stirrer and a thermometer, 300 g of a polystyrene-polybutadiene-polystyrene block copolymer [manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: TR2000], and 3000 g of cyclohexane were added. Charged and dissolved, temperature 60 ° C., 40 ml of di-P-tolyl bis (1-cyclopentadienyl) titanium / cyclohexane solution (concentration 1 mmol / l) and 8 ml of n-butyllithium solution (concentration 5 mmol / l) as hydrogenation catalyst. And a mixture of and under 0 ° C. and a hydrogen pressure of 2.0 kg / cm ² were added, and the hydrogen partial pressure was 2.5 kg / cm ^2.
And reacted for 30 minutes.

The obtained partially hydrogenated polymer solution was dried under reduced pressure to remove the solvent (hydrogenation ratio of the entire butadiene portion was 30).
%). This partially hydrogenated polymer 300 g, toluene 1500
g was added and dissolved. Then, 300 g of a 30 wt% ethyl acetate solution of peracetic acid was continuously added dropwise, and an epoxidation reaction was carried out at 40 ° C. for 4 hours with stirring. The acid value was reduced to 1 or less by returning the reaction solution to room temperature and washing with water (22 wt% toluene-ethyl acetate solution of epoxy-modified block copolymer; E, epoxy equivalent of polymer: 275).

Example 1 In the modified block copolymer solution (A), 0.6 part by weight of sodium dodecylbenzene sulfonate per 100 parts by weight of the polymer, polyoxyethylene nonylphenyl etherate sodium salt ( The average degree of polymerization of polyoxyethylene 10) is 0.5
Part by weight was added and dissolved, and this was mixed with water at a weight ratio of 2: 1 and emulsified with a disper mill.

From the produced emulsion containing toluene and ethyl acetate, toluene and ethyl acetate were removed by evaporation to obtain 50.2% by weight of latex. The amount of coagulation and precipitation of the copolymer in the step of removing the solvent was 0.1% by weight. The mechanical stability of the obtained latex (JIS-K63
81) is 1800 seconds or more, and the mechanical stability at high temperature (JIS-K6381 applied at 70 ° C) is 1700.
It was seconds.

[Example 2] To the modified block copolymer solution (B), 0.6 parts by weight of sodium dodecylbenzene sulfonate was added per 100 parts by weight of the polymer, polyoxyethylene benzyl phenyl ether (polyoxyethylene 0.8 parts by weight of the average degree of polymerization 12) was added and dissolved, and this was mixed with water at a weight ratio of 2: 1 and emulsified with a disper mill. The cyclohexane-ethyl acetate was removed by evaporation from the emulsified liquid containing the generated cyclohexane-ethyl acetate to obtain a latex of 49.2% by weight. The amount of coagulation and precipitation of the copolymer in the solvent removal step is 0.1.
% By weight.

The mechanical stability (JIS-K6381) of the obtained latex was 1800 seconds or more, and the mechanical stability at high temperature (JIS-K6381 was applied at 70 ° C.) was 1700 seconds. .

[Example 3] In the modified block copolymer solution (C), 0.6 part by weight of sodium dodecylbenzene sulfonate per 100 parts by weight of polymer, polyoxyethylene nonylphenyl etherate sodium salt ( The average degree of polymerization of polyoxyethylene 10) is 0.5
Part by weight was added and dissolved, and this was mixed with water at a weight ratio of 2: 1 and emulsified with a disper mill.

From the produced emulsion containing cyclohexane-ethyl acetate, cyclohexane-ethyl acetate was removed by evaporation to obtain 51.2% by weight of latex.

The amount of coagulation and precipitation of the copolymer in the step of removing the solvent was 0.1% by weight.

The mechanical stability (JIS-K6381) of the obtained latex was 1700 seconds, and the mechanical stability at high temperature (JIS-K6381 applied at 70 ° C.) was 1600 seconds.

Example 4 In the modified block copolymer solution (D), 0.6 part by weight of sodium dodecylbenzene sulfonate was added per 100 parts by weight of the polymer, polyoxyethylene benzyl phenyl ether (polyoxyethylene 0.5 part by weight of the average degree of polymerization 12) was added and dissolved, and this was mixed with water at a weight ratio of 2: 1 and emulsified with a disper mill. From the resulting emulsion containing toluene-ethyl acetate, toluene-ethyl acetate was removed by evaporation to obtain 50.6% by weight of latex. The amount of coagulation and precipitation of the copolymer in the step of removing the solvent was 0.1% by weight.

The mechanical stability (JIS-K6381) of the obtained latex was 1800 seconds or longer, and the mechanical stability at high temperature (JIS-K6381 was applied at 70 ° C.) was 1700 seconds. .

Example 5 In the modified block copolymer solution (E), 0.6 parts by weight of sodium dodecylbenzenesulfonate per 100 parts by weight of the polymer, polyoxyethylene nonylphenyl etherate sodium salt ( 0.8 parts by weight of oxyethylene having an average degree of polymerization of 10) was added and dissolved, and this was mixed with water at a weight ratio of 2: 1 and emulsified with a disper mill.

From the produced emulsion containing toluene-ethyl acetate, toluene-ethyl acetate was removed by evaporation to obtain 48.9% by weight of latex. The amount of coagulation and precipitation of the copolymer in the step of removing the solvent was 0.1% by weight.

The mechanical stability of the obtained latex (JIS-K6381) was 1700 seconds, and the mechanical stability at high temperature (JIS-K6381 applied at 70 ° C.) was 1600 seconds.

[Comparative Example 1] Modified block copolymer solution
(A) and water are mixed at a weight ratio of 2: 1 to form a spade.
Emulsified in a mill. From the emulsion containing the generated toluene and ethyl acetate, toluene and ethyl acetate were removed by evaporation,
The copolymer was coagulated and precipitated in the step of removing the solvent.

[0058]

The concentrated latex obtained by the present invention is a crushed molded product, foam rubber, rubber system, processed paper, carpet sizing agent, fiber processing agent, surface coating agent, adhesive paint binder, latex-added asphalt, cement. It can be used for a wide range of applications such as compounding agents. (Below margin)

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Claims (7)

(57) [Claims] 1. A conjugated diene compound of a block copolymer comprising a polymer block (A) mainly containing a vinyl aromatic compound and a polymer block (B) mainly containing a conjugated diene compound in the same molecule. double bonds of the unsaturated carbonless
Such as hydroperoxides and peracids in an active solvent
Latex of epoxy-modified block polymer epoxidized by reaction with an epoxidizing agent . 2. A partially hydrogenated block obtained by partially hydrogenating a block polymer composed of a polymer block mainly containing a vinyl aromatic compound and a polymer block mainly containing a conjugated diene compound in the same molecule. The unsaturated carbon double bond of the conjugated diene compound of the polymer is hydrolyzed in an inert solvent.
Reacts with epoxidizing agents such as peroxides and peracids
The latex of the epoxy-modified block polymer epoxidized by applying . 3. The latex of the epoxy-modified block polymer according to claim 1, which has an epoxy equivalent of 140 to 2700. (1) A block copolymer comprising a polymer block (A) mainly containing a vinyl aromatic compound and a polymer block (B) mainly containing a conjugated diene compound in the same molecule. Double bonds of unsaturated carbons of conjugated diene compounds in hydroperoxides and peracids in an inert solvent
The organic solvent solution of the epoxy-modified block polymer epoxidized by reacting with an epoxidizing agent such as the above is emulsified with water and an emulsifying agent to obtain an organic solvent from the emulsion obtained in the step (2) (1). A method for producing an epoxy-modified block copolymer latex, which comprises a step of removing. 5. The method according to claim 4, wherein the epoxy-modified block copolymer has an epoxy equivalent of 140 to 2700. 6. The emulsifier used in the step (1) is one kind or a mixture of two or more kinds selected from anionic surfactants, nonionic surfactants, or anion-nonionic surfactants. The manufacturing method according to claim 4 . 7. The emulsifier used in the step (1) is a combination system of at least two kinds of anionic surfactant and at least two kinds of nonionic surfactant or anionic-nonionic surfactant. The manufacturing method according to claim 4.