JPH107705A - Dispersant for emulsion polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dispersant for emulsion polymerization which is lowly foaming when used in emulsion polymerization and is excellent in latex dispersion and long-term stability by using a sulfonated styrene polymer having a specified molecular weight. SOLUTION: This emulsifier comprises a sulfonated styrene polymer (salt) having a weight-average molecular weight(Mw) of 2000-1,000,000 and an Mw to Mp ratio of 0.5-1.7 (wherein Mp is the peak top molecular weight). The purpose sulfonated styrene polymer, which is one having a low content of sulfone cross-linkage and a low content of sulfonic anhydride, can be obtained by dissolving a styrene (co)polymer having a specified molecular weight (desirably 5,000-50,000) in a solvent (desirably a 1 or 2C aliphatic halohydrocarbon) inert to the sulfonating agent to be used, adding an ether compound or the like to the solution, and sulfonating the (co)polymer with a sulfonating agent. This emulsifier gives an emulsion latex which has excellent dispersibility and stability and does not discolor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for emulsion polymerization comprising a sulfonated styrene polymer and / or a salt thereof, which is excellent as a dispersant for anionic emulsion polymerization used in the production of emulsion latex. is there.

2. Description of the Related Art Emulsion polymerization generally involves the polymerization of various ethylenically unsaturated monomers or conjugated diene unsaturated monomers, which are hardly soluble in water, alone or as a mixture in an aqueous medium. In this case, an emulsifier is used to provide a polymerization site or to impart dispersion stability to the resulting emulsion latex. Examples of emulsifiers for emulsion polymerization include linear alkyl sulfates, linear alkyl benzene sulfonates, polyoxyethylene alkyl ether sulfates, higher fatty acid salts, anionic surfactants such as resin salts, and polyoxyethylene alkyl ethers. Nonionic surfactants such as polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, and pluronic surfactants have been conventionally used alone or as a mixture.

However, the above surfactants often have insufficient emulsion latex stability. For example, when a latex such as a synthetic rubber such as SBR, NBR or CR is to be obtained by emulsion polymerization, the above-mentioned surfactant may be used. The stability of the emulsion latex obtained with the agent alone is extremely poor, and there are problems such as formation of a large amount of aggregates during polymerization, gelation during long-term storage or transportation, and insufficient freezing stability. Was. Therefore, as agents which function as dispersants in addition to agents which function as emulsifiers for polymerization, JP-A-49-37118 and JP-A-55-142
No. 019 proposes an alkylnaphthalenesulfonic acid or a formalin condensate of naphthalenesulfonic acid. However, the above-mentioned dispersant has a drawback that, although the dispersant has a good effect on the dispersing performance, the system is colored due to having a naphthalene ring, so that it cannot be used for applications that dislike coloring. JP-A-1-268704 discloses that the average molecular weight measured by the GPC method is 100%.
It has been proposed to use a polystyrenesulfonic acid salt having a degree of sulfonation of 0.45 to 0.75 obtained by sulfonating polystyrene having a molecular weight of 0 to 100,000 as a dispersant for emulsion polymerization. However, in these cases, there is no coloring, and the dispersion performance has a corresponding effect. However, there are problems that the stability of the system is deteriorated at the time of polymerization and that foaming occurs at the time of polymerization. Further, JP-A-3-203901 discloses a sulfonated polystyrene having a weight average molecular weight of 2,000 to 100,000,
It has been proposed to improve the foamability by using a polystyrenesulfonic acid salt having a sulfonation ratio of 80 to 95% as a dispersant for emulsion polymerization. In these cases, however, the foamability during polymerization is suppressed. Although the dispersing performance has a corresponding effect, the molecular weight distribution (Mw / Mn) is wide, and the sulfone crosslinked product that causes the increase in the molecular weight distribution thickens the polymerization system or impairs the dispersing performance. Similarly, by the decomposition of sulfonic anhydride, which is responsible for the increase in molecular weight distribution,
Since the coloring and stability of the system are impaired over time, it is still insufficient, and further improvement has been awaited.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to an emulsion polymerization which suppresses foaming during emulsion polymerization, further improves the dispersion performance and stability over time of the resulting emulsion latex, and does not adversely affect the physical properties and properties of the polymer. It is intended to provide a dispersant.

According to the present invention, a styrene-based polymer is used as a raw material, and a styrene-based polymer and a specific compound are dissolved without preparing a complex with sulfuric anhydride, and the solution temperature is determined. When a sulfonating agent is introduced into a solvent inert to the sulfonating reagent held in the range described above and sulfonation is performed, the ratio of the weight average molecular weight (Mw) to the peak top molecular weight (Mp) falls within a specific range. The sulfonated product has little sulfon cross-linking and sulfonic anhydride and exhibits excellent emulsifying and dispersing properties. Therefore, it has been made based on the finding that the use of the sulfonated product can solve the above-mentioned problems. That is, the present invention has a weight average molecular weight of 2,0.
And the weight average molecular weight (M
w) and the ratio Mw / Mp of the peak top molecular weight (Mp) is 0.
A dispersant for emulsion polymerization comprising a water-soluble styrene-based polymer sulfonated product and / or a salt thereof, characterized in that the dispersant is 5 to 1.7.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the weight average molecular weight (Mw) is determined by a conventional method, and the peak top molecular weight (Mw) is determined.
p) is gel permeation chromatography (GP
C) can be easily measured. In the sulfonated styrene polymer, when a sulfone crosslink is formed, the weight-average molecular weight (Mw) increases remarkably, but the change in peak top molecular weight (Mp) is smaller than that, so that Mw / Mp By taking the ratio, it is possible to compare the degree of sulfone crosslinking and the degree of by-product sulfonic anhydride. The dispersant for emulsion polymerization of the present invention has a weight average molecular weight of 1,000 to 500,000, preferably 2,000 to 1,000.
The styrene-based polymer having a molecular weight of 10,000, more preferably 5,000 to 50,000, is used in an amount of 0.1 to 100 parts by weight of the styrene-based polymer.
It is dissolved together with 10 parts by weight of an ether compound and / or a carbonyl group-containing compound, and the solution temperature is adjusted to -10 to 25.
C., preferably from 0 to 20.degree. C., by introducing a sulfonating agent into a halogenated hydrocarbon solvent to react the styrenic polymer with the sulfonating agent, followed by neutralization if desired. However, as long as the obtained styrene polymer sulfonated product has a Mw / Mp of 0.5 to 1.7, other production methods can be used.

In order to produce the sulfonated styrene polymer used in the present invention, it is preferable to use the above specific styrene polymer as a sulfonation raw material. As the styrene-based polymer having such a weight average molecular weight, those produced by a conventionally known method such as radical polymerization, anionic polymerization, and cationic polymerization of a styrene-based monomer can be used. In the present invention, as the styrene-based polymer, not only polystyrene but also a homopolymer or copolymer of styrene having 1 to 5 carbon atoms and optionally having a substituent, Examples include a polymerizable monomer such as a copolymer with a diene having 4 to 10 carbon atoms. Specifically, poly-α-methylstyrene,
One or a mixture of two or more of a styrene-α-methylstyrene copolymer, a styrene-butadiene copolymer, a styrene-isoprene copolymer, and a styrene- (meth) acrylic acid-based copolymer can be used.

[0006] Solvents inert to the sulfonating reagent include:
An aliphatic halogenated hydrocarbon having 1 to 2 carbon atoms is preferably used. Specific examples of such halogenated hydrocarbons include those inert to sulfonating agents such as dichloromethane, chloroform, carbon tetrachloride, chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, tetrachloroethane, and dibromoethane. Is raised. If the carbon number of the halogenated hydrocarbon is 3 or more, the solubility of the sulfonating agent deteriorates, which is not preferable. The amount of the solvent used is suitably about 1 to 30 parts by weight per 1 part by weight of the styrene-based polymer. To produce the sulfonate used in the present invention,
First, the raw material styrene-based polymer is dissolved in a solvent inert to the sulfonating reagent, and an ether compound and / or a carbonyl group-containing compound is added as an additive in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the styrene-based polymer. Parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.1 to 2 parts by weight. It is preferable that the additive is completely mixed with the solvent and becomes uniform. If the addition amount is less than 0.1 part by weight, intramolecular or intermolecular crosslinking is likely to occur, and the effect of the addition is small. On the other hand, if it exceeds 10 parts by weight, the sulfonating agent does not react effectively with the styrene-based polymer, and problems such as a decrease in the sulfonation rate occur.

Various organic compounds can be used as the ether compound and / or the carbonyl group-containing compound used in the sulfonation. Examples of the ether compound include alkyl ethers having 3 to 21 carbon atoms, alkyl allyl ethers, allyl ethers, dioxane, furan,
Examples thereof include polyalkylene glycols, mono- or diethers or esters thereof, and sulfates thereof. Among these, preferred ether compounds include those represented by formulas (1) and (2).

Embedded image R ₁ —O—R ₂ (1) A ₁ —O— (R ₃ —O) n —A ₂ (2) (wherein, R ₁ and R ₂ each independently have 1 to 1 carbon atoms. 10
Represents an alkyl group, a cycloalkyl group or a phenyl group, wherein A ₁ and A ₂ each independently represent hydrogen,
10 alkyl group, a phenyl group, an alkyl phenyl group or a -SO ₃ M group having a 1-3 substituents an alkyl group having 1 to 9 carbon atoms, M represents hydrogen, an alkali metal or an ammonium group, R ₃ represents an alkylene group having 2 to 4 carbon atoms, and n represents a number of 1 to 20. )

The ether compound of the formula (1) includes diethyl ether, diisopropyl ether, dibutyl ether, anisole, diphenyl ether, dioxane,
Examples of the ether compound of the formula (2) include polyethylene glycols, polypropylene glycols, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyethylene glycol disulfate. Examples of the carbonyl group-containing compound include ketone compounds such as alkyl ketones having 3 to 21 carbon atoms, alkyl allyl ketones, and allyl ketones;
Carboxylic acid compounds such as aliphatic carboxylic acids and allyl carboxylic acids, and ester compounds thereof. Although aldehydes can be used, ketone compounds, carboxylic acid compounds and ester compounds are preferably used. Among these, preferred carbonyl group-containing compounds include those represented by formulas (3) and (4).

[0009]

Embedded image R ₄ —CO—R ₅ (3) R ₆ —COOX (4) (wherein, R ₄ and R ₅ each independently have 1 to 10 carbon atoms.
R ₆ represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, a phenyl group or an alkyl group having 1 to 9 carbon atoms,
X represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or -COR ₇ , and R ₇ represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or Represents a phenyl group. Examples of the ketone compound of the formula (3) include acetone, acetophenone, acetylacetone, diphenyl ketone, cyclohexanone, methylcyclohexanone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone.

The carboxylic acid compound or ester compound of the formula (4) includes benzoic acid, benzoic esters, isophthalic acid, phthalic anhydride, acetic acid, acetic anhydride, acetic esters, propionic acid, propionic anhydride, propionic acid Esters, butyric acid, butyric anhydride, butyric esters, valeric acid, valeric esters, cyclohexylcarboxylic acid, and the like. Among the above compounds, polyethylene glycols and carboxylic acids are particularly preferred. As the sulfonating agent, fuming sulfuric acid, sulfuric anhydride and the like can be used, but sulfuric anhydride is particularly preferred. Sulfonation is preferably performed using a sulfonating agent in an amount of 0.5 to 2.0 moles per unit monomer with respect to the styrene-based polymer as a raw material, and is preferably used.
It is in the range of 0.8 to 1.5.

A styrenic polymer and an ether compound and / or
Alternatively, the styrene polymer can be sulfonated by introducing a sulfonating agent into a solvent inert to a sulfonating reagent obtained by dissolving a carbonyl group-containing compound by an arbitrary method. At this time, it is important that the temperature of the halogenated hydrocarbon solution immediately before contact with the sulfonating agent is kept at -10 to 25C, preferably 0 to 20C. If the temperature is lower than -10 ° C, the reaction hardly proceeds. If the temperature is higher than 25 ° C, the temperature immediately after the contact becomes too high instantaneously, and sulfone crosslinking and by-product of sulfonic anhydride easily occur, which is not preferable. The sulfonation reaction temperature is suitably from 20 to 60 ° C, preferably from 30 to 50 ° C. By the sulfonation reaction, a styrene-based polymer sulfonate is obtained as a slurry dispersed in a halogenated hydrocarbon solvent. This is added to water to dissolve the styrene polymer sulfonate, and then separated by solvent or neutralized with a suitable neutralizing agent.
An aqueous solution of a sulfonated styrene polymer is obtained by solvent separation. Here, as the neutralizing agent, for example, lithium hydroxide, sodium hydroxide, alkali metal hydroxides such as potassium hydroxide, calcium hydroxide, magnesium hydroxide, alkaline earth metal hydroxides such as barium hydroxide, Ammonia or aqueous ammonia, or monoethanolamine, diethanolamine, triethanolamine, morpholine, ethylamine, butylamine,
Organic amines such as coconut oil amine, tallow amine, ethylenediamine, hexamethylenediamine, diethylenetriamine, and polyethyleneimine.

The obtained sulfonated styrene polymer is subjected to gel permeation chromatography (GP).
The weight average molecular weight (Mw) measured according to C) is 2,000
１００1,000,000, preferably 5,000〜200,000, more preferably 10,000〜１０100,000, and the ratio (Mw / Mp) of the peak top molecular weight (Mp) to the weight average molecular weight (Mw) is 0.5５〜0.5.
1.7 (preferably 1.0 to 1.5). Mw / M
If p exceeds 1.7, the amount of by-product sulfone cross-linking and sulfonic anhydride increases remarkably, and dispersibility and stability with time decrease. The sulfonation ratio per styrene-based unit monomer is 75% or more, preferably 80 to 100%. Furthermore, the obtained aqueous solution of the styrene polymer sulfonated product may contain salts and the like as by-products. Normal,
The amount is 3 to 1 based on the sulfonated styrene polymer.
5% by weight. The dispersant of the present invention can be used in a state containing these by-products as they are, or can be used after removing the by-products.

The dispersant for emulsion polymerization of the present invention thus obtained is used as it is in an aqueous solution (concentration of 5 to 30% by weight).
After drying by a conventional method or a concentrate (concentration: 30 to 60% by weight) or a powder, the powder is practically used as a powder. Emulsion polymerization using the dispersant for emulsion polymerization of the present invention can be performed by a known method. For example, based on 100 parts by weight of the monomer, 60 to 500 parts by weight of water, 0.5 to 1 emulsifier for emulsion polymerization
0 parts by weight, 0.5 to 10 parts by weight of the dispersant for emulsion polymerization of the present invention, an appropriate amount of a polymerization initiator, and if necessary, an inorganic salt and a chain transfer agent are added, and an appropriate temperature is set under a nitrogen atmosphere. To carry out the polymerization reaction. The monomers used here include conjugated dienes such as isoprene, butadiene and 2-cyanobutadiene, halogenated conjugated dienes such as chloroprene, 1-chlorobutadiene and 2,3-dichlorobutadiene, vinyl chloride, and chloride. Vinyl halides such as vinylidene, vinyl esters such as vinyl acetate, vinyl ethers such as methyl vinyl ether and butyl vinyl ether, aromatic vinyls such as styrene and α-methylstyrene, methyl acrylate, butyl acrylate, methyl methacrylate And methacrylic acid esters such as butyl methacrylate. These monomers can be used alone or, if necessary, as a mixture of two or more kinds.

[0014]

According to the present invention, the weight average molecular weight is 2,000.
When the ratio of the sulfonated styrene-based polymer Mw / Mp is 0.5 to 1.7, an effect of controlling the spread of the dispersant molecules and controlling the adsorption capacity can be obtained. , Dispersibility and the like are greatly improved. By using this as a dispersant for emulsion polymerization, in the case of producing an emulsion latex by emulsion polymerization, polymerization can be carried out without causing problems such as deterioration of dispersion stability of the system during polymerization and foaming. Further, it is suitable for industrial emulsion latex production because it improves the stability over time of the produced latex and enables production without affecting its physical properties or product properties. Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0015]

【Example】

Synthesis Example 1 100 parts by weight of polystyrene having a weight average molecular weight of 2,000 (Mw / Mn = 1.8) was dissolved in 400 parts by weight of 1,2-dichloroethane, and ethylene glycol (average molecular weight 2
00) 1.0 part by weight was added to prepare a raw material solution. The raw material solution was continuously supplied to a sulfonation reactor equipped with a turbine-type stirrer together with sulfuric anhydride as a sulfonating reagent at a temperature of 10 ° C to perform a sulfonation reaction at 45 ° C. In this case, the feed rate was 24 g / min for the raw material, 4.4
5 g / min, molar ratio of sulfuric anhydride / polystyrene is 1.2
0, and the reactor was jacketed and had a tank capacity of 400
ml. 10% of the obtained sulfonated product
After neutralization using an aqueous NaOH solution, the mixture was separated to obtain sodium polystyrene sulfonate. The weight average molecular weight of the obtained sodium polystyrene sulfonate is 3,800, and Mw / Mp is 1.
1. The sulfonation rate was 94%. Synthetic Examples 2 to 7 Various sodium polystyrene sulfonates were obtained in exactly the same manner as in Synthetic Example 1 except that polystyrene having the molecular weight and molecular weight distribution shown in Table 1 was used. The analytical values are shown in the same table.

Synthesis Example 8 Polystyrene having a weight average molecular weight of 9,700 (Mw / Mn = 2.0) was used, and sodium polystyrene sulfonate was obtained in exactly the same manner as in Synthesis Example 1 except that polyethylene glycol was not used. . The weight average molecular weight of the obtained Na polystyrene sulfonate was 37,000, Mw / Mp was 2.5, and the sulfonation ratio was 92%. Synthesis Example 9 Polystyrene having a weight average molecular weight of 9,700 (Mw / Mn = 2.0) was used, and the temperature of the raw material solution was changed to 30 ° C., and exactly the same as in Synthesis Example 1 except that Na polystyrene sulfonate was used.
I got The weight average molecular weight of the obtained sodium polystyrene sulfonate was 27,000, Mw / Mp was 1.9, and the sulfonation ratio was 92%. Synthesis Example 10 Polystyrene having a weight average molecular weight of 9,700 (Mw / Mn = 2.0) was used, and polyethylene glycol was not used.
Na polystyrene sulfonate was obtained in exactly the same manner as in Synthesis Example 1 except that the temperature of the raw material solution was 30 ° C. The weight average molecular weight of the obtained sodium polystyrene sulfonate is 39,0.
The Mw / Mp was 2.5, and the sulfonation ratio was 92%.

The properties of the polystyrene sulfonate prepared in the above synthesis examples were determined as follows. (1) Molecular weight of polystyrene Standard polystyrene is used as a standard substance, and Tosoh Corporation's TSKG1000HXL (7.8 mm ID ×
30cm), UV detector (wavelength 266nm)
And determined by GPC. When styrene was detected in the sample, styrene was excluded and the weight average molecular weight and peak top molecular weight were determined. (2) Molecular weight of polystyrene sulfonic acid Standard sodium polystyrene sulfonic acid is used as a standard substance, and TSK G manufactured by Tosoh Corporation is used as a separation column.
3000SW (7.5mm ID x 30cm) and TSK G
The weight average molecular weight and the number average molecular weight were determined by GPC using 4000 SW (7.5 mm ID × 30 cm) and an ultraviolet detector (measuring wavelength 238 nm). (3) Sulfonation rate Total S and C were determined by elemental analysis and calculated by the following equation.

[Formula 1] 100 × [(S in total S-Na ₂ SO ₄ ) / 3
2] / [All C / 96]

[0018]

[Table 1] Table-1 Synthesis Example Properties of Raw Material Polystyrene Properties of Polystyrene Na Sulfonate Molecular Weight Molecular Weight Distribution Molecular Weight Mw / Mp Sulfonation Rate (Mw) (Mw / Mn) (Mw) (%) 1 2,000 1.8 8,800 1.194 2 5,000 1.99 9,800 1.2 293 3 9,700 2.0 22,000 1.3 944 448 000 2.1 96,000 1.3 93 5 200,000 443,000 1.5 92 6 1,000 1.9 1,900 0.9 94 77,600 2.4 1,131,000 1.6 93 8 9,700 2.0 37,000 2.5 9299 9,700 2. 0 27,000 1.9 92 10 9,700 2.0 39,000 2.5 92

Example 1 A reaction vessel equipped with a thermometer, a nitrogen inlet tube, a stirrer, a reflux condenser, and a dropping funnel was charged with 100 parts by weight of styrene monomer, sodium polyoxyethylene lauryl ether sulfate 1.0.
1.0 part by weight of the sulfonated polystyrene obtained in Synthesis Example 1 as a dispersant for emulsion polymerization, 0.25 part by weight of dodecyl mercaptan, and 100 parts by weight of ion-exchanged water were charged and replaced by nitrogen. Further, 1.0 part by weight of a 0.5% by weight aqueous solution of potassium persulfate was dropped into the reaction vessel as a catalyst, and polymerization was carried out at 40 ° C. under nitrogen reflux. At a polymerization conversion of 70%, t-butylcatechol and phenothiazine were each added.
0.01 part by weight was added to the reaction vessel to stop the polymerization. The obtained latex emulsion was evaluated for cohesiveness, foaming property and coloring property, and the results are shown in Table 2. Examples 2 to 5 Emulsion polymerization was performed in the same manner as in Example 1 except that the polystyrene sulfonate obtained in Synthesis Examples 2 to 5 was used instead of the polystyrene sulfonate obtained in Synthesis Example 1, and evaluation was performed. did. The results are shown in Table 2. Examples 6 to 15 Instead of using a styrene monomer as the monomer, an example was shown in which the monomers shown in Table 2 below were used, and the polystyrene sulfonate shown in Table 2 was used instead of the polystyrene sulfonate obtained in Synthesis Example 1. Emulsion polymerization was carried out in the same manner as in Example 1 and evaluated. The results are shown in Table 2.

Comparative Examples 1 to 5 Emulsion polymerization was carried out in the same manner as in Example 1 except that the sulfonated polystyrene obtained in Synthesis Examples 6 to 10 was used instead of the sulfonated polystyrene obtained in Synthesis Example 1. Performed and evaluated. The results are shown in Table-3.

Comparative Examples 6 to 15 Instead of using a styrene monomer as a monomer, a monomer shown in Table 3 below is used, and a polystyrene sulfonate shown in Table 3 is used in place of the polystyrene sulfonate obtained in Synthesis Example 1. Except for the above, emulsion polymerization was carried out in the same manner as in Example 1 and evaluated. The results are shown in Table-3. Comparative Example 16 Emulsion polymerization was carried out and evaluated in the same manner as in Example 1 except that a sulfonated product of polystyrene was not added. The results are shown in Table-3.

The cohesiveness and stability over time (colorability and sedimentation) were evaluated as follows. (1) Aggregation The produced emulsion was filtered with an 80-mesh sieve, the remaining amount of the filtration was washed with water, and then dried. (2) Stability over time After storing the obtained emulsion at 60 ° C. for one month,
Evaluation was made according to the following criteria. (2-1) Sedimentation ○: No sedimentation ×: Sedimentation present (2-2) Colorability Judgment was made visually.

[0023]

[Table 2] Table 2 (Example) Example of stability with time Monomer Dispersant Coagulability Sedimentation Colorability 1 Styrene Synthesis Example 1 0.43 ○ Colorless 2 Styrene Synthesis Example 2 0.27 ○ Colorless 3 Styrene Synthesis Example 3 0.29 ○ Colorless 4 Styrene Synthesis Example 4 0.38 ○ Colorless 5 Styrene Synthesis Example 5 0.43 ○ Colorless 6 Styrene / propylene (6: 4) Synthesis Example 1 0.41 ○ Colorless 7 Styrene / butadiene (6: 4) Synthesis Example 10 .49 ○ Colorless 8 Styrene / BVE * 1 (6: 4) Synthesis Example 2 0.31 ○ Colorless 9 Styrene / BA * 2 (6: 4) Synthesis Example 2 0.26 ○ Colorless 10 Styrene / MMA * 3 (6: 4) Synthesis Example 3 0.35 ○ No Color 11 Chloroprene / BA (6: 4) Synthesis Example 3 0.41 ○ No Color 12 Butadiene / MMA (6: 4) Synthesis Example 4 0.47 ○ No Color 13 BA / MMA (6: 4) Synthesis Example 4 0.36 ○ No Color 14 Butadiene / vinyl acetate (6: 4) Synthesis Example 5 0.52 ○ No Color 15 BA / vinyl acetate (6: 4) Synthesis Example 5 0.41 ○ No color * 1; B VE: butyl vinyl ether (same below) * 2; BA: butyl acrylate (same below) * 3; MMA: methyl methacrylate (same below)

[0024]

[Table 3] Table-3 (Comparative example) Comparative Example of Stability over Time Monomer Dispersant Aggregation Sedimentability Colorability 1 Styrene Synthesis Example 6 1.67 × Colorless 2 Styrene Synthesis Example 7 Thickening ― − 3 Styrene Synthesis Example 8 1.60 × Light Red 4 Styrene Synthesis Example 9 0.65 × pale red 5 styrene Synthesis Example 10 1.70 × pale red 6 Styrene / propylene (6: 4) Synthesis Example 6 1.52 × no color 7 Styrene / butadiene (6: 4) Synthesis Example 7 Thickening − -8 Styrene / BVE (6: 4) Synthesis Example 8 1.81 × pale red 9 Styrene / BA (6: 4) Synthesis Example 9 0.88 × pale red 10 Styrene / MMA (6: 4) Synthesis Example 10 1 .57 × pale red 11 chloroprene / BA (6: 4) Synthesis Example 6 1.61 × colorless 12 butadiene / MMA (6: 4) Synthesis Example 7 Thickening − − 13 BA / MMA (6: 4) Synthesis Example 8 1.52 × light red 14 butadiene / vinyl acetate (6: 4) Synthesis Example 9 0.77 × light red 15 BA / vinyl acetate (6: 4) Synthesis Example 10 1.68 × light red 16 No styrene added 2 .5 × no color

Claims (1)

[Claims] 1. A styrenic compound having a weight average molecular weight of 2,000 to 1,000,000 and a ratio Mw / Mp of the weight average molecular weight (Mw) to the peak top molecular weight (Mp) of 0.5 to 1.7. A dispersant for emulsion polymerization, comprising a polymer sulfonate and / or a salt thereof.