JP2007077181A - Emulsifying agent for emulsion polymerization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emulsifying agent for emulsion polymerization excellent in emulsion stability and mechanical stability of a polymer emulsion obtained, capable of providing a polymer emulsion scarcely causing foaming and further, excellent in glossiness of a film. <P>SOLUTION: The emulsifying agent composition for emulsion polymerization comprises a nonionic surfactant (a) represented by general formula (1): R<SP>1</SP>O-(A<SP>1</SP>O)<SB>z</SB>-X (wherein R<SP>1</SP>is a 9-11C alkyl group having ≥80 wt.% alkyl group content; A<SP>1</SP>O is a 2-4C oxyalkylene group; z is an integer of 1-50; X is an anion hydrophilic group; addition form of A<SP>1</SP>O is random addition, block addition or mixed addition thereof) and having 1.05-1.50 of a degree of branching of a raw material alcohol as an essential component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an emulsifier for emulsion polymerization used in emulsion polymerization.

  Until now, as an emulsifier for emulsion polymerization, an ether type nonionic emulsion polymerization emulsifier in which an alkylene oxide such as ethylene oxide is added to an alkylphenol such as nonylphenol or octylphenol has been widely used.

  However, in recent years, since alkylphenol is hardly biodegradable, it has been pointed out that the burden on the environment is large. For this reason, as a hydrophobic group raw material for emulsifiers for emulsion polymerization, alkylphenols have been shifted to aliphatic alcohols.

On the other hand, an emulsifier for emulsion polymerization is disclosed in which the hydrophobic group is a specific alcohol residue, has good biodegradability, and has little influence on the environment (Patent Document 1).
JP 2003-128709 A

  The performance required for the emulsion polymerization emulsifier includes emulsion stability during polymerization, mechanical stability of the resulting polymer emulsion, and the like. Although effective, it is still insufficient and there is room for improvement.

  In addition, when the obtained polymer emulsion is used for coating applications, it is required that the polymer emulsion has less foaming and that the film formed from the emulsion is excellent in glossiness. The polymer emulsion thus polymerized is still insufficient in these respects.

  The present invention has been made in view of the above points, and provides a polymer emulsion having excellent emulsion stability during polymerization, mechanical stability of the resulting polymer emulsion, less foaming, and excellent film gloss. An object of the present invention is to provide an emulsifier for emulsion polymerization.

  While the present inventors are diligently considering in view of the above points, an emulsifier for emulsion polymerization containing an anionic surfactant obtained from a raw material alcohol having a branching degree within a specific range as a hydrophobic group raw material We found a solution and completed the present invention.

That is, the invention according to claim 1 is an anionic surfactant represented by the following general formula (1), wherein the raw alcohol has a degree of branching of 1.05 to 1.50. It is an emulsifier for emulsion polymerization characterized by comprising the obtained anionic surfactant (a) as an essential component.
^{R 1 O- (A 1 O)} z-X (1)
(In the formula, R ¹ represents an alkyl group having a C 9-11 alkyl group content of 80 wt% or more, A ¹ O represents a C 2-4 oxyalkylene group, and z Is an integer of 1 to 50, X represents an anionic hydrophilic group, and the addition form of A ¹ O is random addition, block addition, or mixed addition thereof.

The invention according to claim 2 is a nonionic surfactant in which the anionic surfactant (a) is an anionic surfactant represented by the following general formula (2), and the degree of branching of the raw material alcohol is 1. Anionic surfactant (b) obtained from the agent, and an anionic surfactant represented by the general formula (3), which is obtained from the nonionic surfactant having a branching degree of the raw material alcohol of 2. The agent (c) is contained as an essential component, and the weight ratio of the component (b) to the component (c) is (b) / (c) = 50/50 to 95/5. It is an emulsifier for emulsion polymerization as described.
^{R 2 O- (A 2 O)} m-X (2)
^{R 3 O- (A 3 O)} n-X (3)
(In the formula, R ² and R ³ are alkyl groups having 9 to 11 carbon atoms and the alkyl group content is 80% by weight or more, and A ² O and A ³ O are carbon atoms having 2 to 4 carbon atoms. Represents an oxyalkylene group, m and n are integers of 1 to 50, and X represents an anionic hydrophilic group, and the addition form of A ² O and A ³ O is random addition, block addition, or mixed addition thereof. )

In the invention according to claim 3, the anionic surfactant represented by the general formulas (1), (2), and (3) is obtained from an alcohol represented by the following general formula (4) obtained from the Gerve reaction. 3. The emulsifier for emulsion polymerization according to claim 1, wherein R ⁴ and R ⁵ are a linear alkyl group or a branched alkyl group.
R ⁴ —CH (R ⁵ ) —CH ₂ —OH (4)

The invention according to claim 4 is characterized in that the anionic surfactants (b) and (c) are those in which R ^{2 in the} general formula (2) is ² -alkyl-1-alkanol having 10 carbon atoms, and the general formula (3). any of claims 1 ^{to 3, R 3} of) is characterized in that it is derived from 2-alkyl-4-alkyl-1 -alkanols and / or 2-alkyl-5-alkyl-1 -alkanols having 10 carbon atoms It is an emulsifier for emulsion polymerization as described above.

  In the invention according to claim 5, the anionic surfactant has a group represented by any one of the following general formulas (5) to (9) as X in the general formulas (1) to (3). It is an emulsifier for emulsion polymerization in any one of Claims 1-4 characterized by the above-mentioned.

X: —SO ₃ M (5)
-PO ₃ M ₂ (6)
-P (R ⁶ ) O ₂ (7)
-CH ₂ COOM (8)
—CO—CH ₂ —CH (SO ₃ M) COOM (9)
(In the formula, each M is independently a hydrogen, alkali metal, NH ₄ or alkanolamine residue, and R ⁶ is a residue excluding X in the general formulas (1) to (3).)

  The emulsifier for emulsion polymerization according to the present invention can be preferably used as an emulsifier for emulsion polymerization because a polymer emulsion having good polymerization stability and chemical stability and less foaming can be obtained. In addition, a film having a good gloss can be obtained when used for paint applications.

In the general formula (1), R ¹ is an alkyl group having a C 9-11 alkyl group content of 80% by weight or more. In the present invention, a branched aliphatic alcohol having 9-11 carbon atoms is used. Used as a raw material alcohol for hydrophobic groups. Specific examples of the alkyl group include a branched nonyl group, a branched decyl group, and a branched undecyl group.

  Although it does not specifically limit, if it is in the limited range of this invention, the mixture of a C9-C11 branched aliphatic alcohol and other alcohol may be sufficient as a hydrophobic group raw material. When alcohol other than the branched aliphatic alcohol having 9 to 11 carbon atoms is mixed, the ratio is preferably less than 20% by weight.

The degree of branching of the branched aliphatic alcohol is 1.05 to 1.50. When the degree of branching exceeds 1.5, the particle size distribution of the resulting polymer emulsion becomes rough, and a film having good gloss cannot be obtained when used in coating applications. On the other hand, if the degree of branching is less than 1.05, foaming of the polymer emulsion obtained by emulsion polymerization becomes large. Moreover, the selection range of the monomer which can be used becomes narrow. The degree of branching is a numerical value obtained by obtaining the number of methyl groups by H ¹ -NMR measurement of the raw material alcohol and subtracting 1 corresponding to the terminal methyl group site.

  In the present invention, the anionic surfactant (a) represented by the general formula (1) is composed of the surfactants (b) and (c) represented by the general formulas (2) and (3). It may consist of a mixture.

The anionic surfactant (b) represented by the general formula (2) is an anionic surfactant obtained from a nonionic surfactant having a branching degree of the raw material alcohol of 1, and R ^{2 in} the formula represents the number of carbon atoms. Is an alkyl group in which the content of an alkyl group of 9 to 11 is 80% by weight or more. The anionic surfactant (c) represented by the general formula (3) is an anionic surfactant obtained from a nonionic surfactant having a branching degree of raw material alcohol of 2, and R ³ in the formula is The alkyl group having 9 to 11 carbon atoms and an alkyl group content of 80% by weight or more.

In the present invention, the anionic surfactants (b) and (c) represented by the above general formulas (2) and (3) are derived from an alcohol represented by the following general formula (4) obtained from the Gerve reaction. The ones made are preferred. Here, R ⁴ and R ⁵ are a linear alkyl group or a branched alkyl group.

R ⁴ —CH (R ⁵ ) —CH ₂ —OH (4)
In addition, the anionic surfactants (b) and (c) represented by the general formulas (2) and (3) are obtained from 2-alkyl-1-alkanol in which R ^{2 in the} general formula (2) has 10 carbon atoms. And R ³ in the general formula (3) is derived from 2-alkyl-4-alkyl-1-alkanol and / or 2-alkyl-5-alkyl-1-alkanol having 10 carbon atoms. Preferably there is.

  Specific examples of the raw material alcohol (b) include 2-propylhexanol, 2-ethylheptanol, 2-propylheptanol, 2-butylheptanol, 2-propyloctanol, and the like (c). Alcohols include 4-methyl-2-propylhexanol, 2-ethyl-4-methylhexanol, 2-butyl-4-methylhexanol, 5-methyl-2-propylhexanol, 2-ethyl-5-methylhexanol, 2- Examples include butyl-5-methylhexanol.

  The anionic surfactant (a) of the present invention contains the anionic surfactants (b) and (c) as essential components, and the weight ratio of the component (b) to the component (c) is (b) / ( c) = 50/50 to 95/5 is preferred. More preferably, it is 70/30-90/10.

  When the weight ratio (b) / (c) is less than 50/50, the particle size distribution of the resulting polymer emulsion becomes rough, and a film having good gloss cannot be obtained when used in coating applications. On the other hand, when (b) / (c) is greater than 95/5, foaming of the polymer emulsion obtained by emulsion polymerization becomes large, and the selection range of monomers that can be used becomes narrow.

In the above general formulas (1), (2), and (3), (A ¹ O), (A ² O), and (A ³ O) are all formed by addition polymerization of alkylene oxide to raw material alcohol. An oxyalkylene group having 2 to 4 carbon atoms (polyoxyalkylene moiety), among which an oxyethylene group or an oxypropylene group is preferable.

  In this case, the addition form in the case of two or more types of alkylene oxides may be random addition, block addition, or mixed addition thereof. More preferably, it is preferable to first add propylene oxide and then block-add ethylene oxide to the raw material alcohol so that the alcohol residue side becomes an oxypropylene group portion. By adopting such a block addition form, the polymerization stability at the time of emulsion polymerization is improved, and the mechanical stability of the resulting polymer emulsion and the gloss of the film are improved. Note that z, m, and n are all integers of 1 to 50, and m and n may be the same or different, but are preferably the same number. In addition, in the case of commercial production, a commonly used production method can be applied, and under normal addition polymerization conditions, components having z, m, and n of 0 remain, but the emulsifier for emulsion polymerization of the present invention But it is acceptable.

  Moreover, in General formula (1)-(3), X is an anionic hydrophilic group.

  X preferably has a group represented by any one of the following general formulas (5) to (9).

X: —SO ₃ M (5)
-PO ₃ M ₂ (6)
-P (R ⁶ ) O ₂ (7)
-CH ₂ COOM (8)
—CO—CH ₂ —CH (SO ₃ M) COOM (9)
Here, M in the formula independently represents an alkali metal such as hydrogen, lithium, sodium or potassium, NH ₄ , or an alkanolamine residue such as ethanolamine, diethanolamine or propanolamine. R ⁶ is a residue excluding X in the general formulas (1) to (3). Therefore, the above formula (6) represents a phosphoric acid monoester, and the above formula (7) represents a phosphoric acid diester.

  The emulsifier for emulsion polymerization of the present invention may be mixed after anionizing the alkylene oxide adduct of each raw material alcohol, or may be mixed before anionizing the alkylene oxide adduct of each alcohol. In addition, they may be mixed before adding alkylene oxide to each alcohol.

  The emulsifier for emulsion polymerization of the present invention comprises the anionic surfactant (a) represented by the general formula (1) described above, or the anionic surfactants (b) represented by the general formulas (2) and (3) ( This mixture contains the mixture of c), and this emulsifier for emulsion polymerization can be applied to emulsion polymerization of various monomers.

  At the same time, for the purpose of improving the processing characteristics in the subsequent steps, other surfactants can be used in combination as necessary. Examples of such other surfactants include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer, and alkylbenzene sulfonates. Other anionic surface activity such as rosin acid soap, aliphatic soap, alkyl sulfonate, alkyl naphthalene sulfonate, alkyl sulfosuccinate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate Agents.

  Although the kind of monomer to which the emulsifier for emulsion polymerization of the present invention can be applied is not particularly limited, examples include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, Acrylic monomers such as glycidyl methacrylate, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, acrylamide, methacrylamide, acrylic acid hydroxyethyl ester, methacrylic acid hydroxyethyl ester, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, etc. , Aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, divinylbenzene, vinyl ester monomers such as vinyl acetate, chloride Examples thereof include halogenated olefin monomers such as vinyl and vinylidene chloride, conjugated diolefin monomers such as butadiene, isoprene, and chloroprene, and others, ethylene, itaconic acid, fumaric acid, maleic acid, and methyl maleate. These monomers can be used alone or in combination of two or more.

  The emulsifier for emulsion polymerization of the present invention is usually used in an amount of 0.1 to 20% by weight, preferably 0.2 to 5% by weight, based on the total amount of monomers.

  For emulsion polymerization using the emulsifier for emulsion polymerization of the present invention, a conventionally known polymerization initiator can be used without particular limitation. Representative examples include hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane). And dihydrochloride.

  Further, redox polymerization can be performed using sodium bisulfite, ferrous ammonium sulfate, or the like as a polymerization accelerator.

  Further, as chain transfer agents, mercaptans such as α-methylstyrene dimer, n-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, carbon tetrachloride, carbon tetrabromide Halogenated hydrocarbons such as may be used.

  The polymer emulsion obtained by using the emulsifier for emulsion polymerization of the present invention includes, for example, binders for printing inks, paints (for construction, household use, cans, electrodeposition coating, etc.), binders for ink jet media, and adhesives. It can be applied to wood, metal, paper, cloth, plastic, ceramic, other concrete, etc. as an adhesive, a coating agent, an impregnation reinforcing agent and the like.

  Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited thereto. In the following examples, “part” is based on mass unless otherwise specified.

[Synthesis of raw material nonionic surfactant]
The raw material nonionic surfactants [A] to [N] shown in Table 1 below were synthesized as follows.

<Production Example 1>
In an autoclave, 2-propylheptanol and 4-methyl-2-propylhexanol in a ratio of 9: 1 alcohol (branch degree 1.1) 158 parts (1 mol), potassium hydroxide 0.38 parts (0.007 mol) , 0.1% per crude product), and the inside of the autoclave was purged with nitrogen, and then the pressure was reduced at 70 ° C. with stirring. After the internal pressure in the reactor reached 2.7 kPa, dehydration was continued for 30 minutes. did. Next, after introducing 220 parts (5 moles) of ethylene oxide at a temperature of 120 ° C. and a reaction pressure of 0.25 MPa, the reaction temperature was maintained and aging was performed until the internal pressure decreased and became constant. Thereafter, the reaction solution was cooled to 70 ° C., and then neutralized with 0.44 part of glacial acetic acid (0.007 mol, 1.1 mol equivalent to potassium hydroxide), and the raw material nonionic surfactant [A ] Was obtained.

<Production Example 2>
2-propylheptanol and 4-methyl-2-propylhexanol are alcohols in a ratio of 9: 1 (branch degree 1.1), the alcohols shown in Table 1 below and the ratios thereof are changed, and the amount of ethylene oxide introduced is changed. The raw material nonionic surfactant [B] [C] was changed in the same manner as in Production Example 1 except that the ratio was changed to the ratio shown in Table 1 below and the catalyst amount was changed accordingly (0.1% per crude product). [E] [F] [H] [I] [J] [M] [N] were obtained.

<Production Example 3>
In an autoclave, 2-propylheptanol and 4-methyl-2-propylhexanol in a ratio of 9: 1 alcohol (branch degree 1.1) 158 parts (1 mol), potassium hydroxide 0.88 parts (0.016 mol) , 0.1% per crude product), and the inside of the autoclave was purged with nitrogen, and then the pressure was reduced at 70 ° C. with stirring. After the internal pressure in the reactor reached 2.7 kPa, dehydration was continued for 30 minutes. did. Subsequently, after raising the temperature to 110 ° C., 58 parts (1 mol) of propylene oxide was introduced at a reaction pressure of 0.20 MPa. After the introduction of propylene oxide, the reaction temperature was maintained, and aging was performed until the internal pressure decreased and became constant. Next, after introducing 660 parts (15 moles) of ethylene oxide at a temperature of 120 ° C. and a reaction pressure of 0.25 MPa, the reaction temperature was maintained and aging was performed until the internal pressure decreased and became constant. Thereafter, the reaction solution was cooled to 70 ° C., and then neutralized with 1.82 parts of 85% by weight of lactic acid (0.017 mol, 1.1 mol equivalent per potassium hydroxide) to obtain a raw material nonionic surfactant. [D] was obtained.

<Production Example 4>
2-Propylheptanol and 4-methyl-2-propylhexanol were used in the same manner as in Production Example 3 except that the alcohol (branch degree 1.1) in a ratio of 9: 1 was changed to the alcohol and the ratio shown in Table 1 below. The raw material nonionic surfactant [G] [K] [L] was obtained.

[Degree of branching]
It is a numerical value obtained by obtaining the number of methyl groups by H ¹ -NMR measurement of the raw material alcohol and subtracting 1 corresponding to the terminal methyl group site.

[Synthesis of emulsifier]
Using the raw material nonionic surfactant obtained above, the present invention products [1] to [9] and comparative products [1] to [9], which are emulsifiers shown in Table 2 below, were synthesized as follows. did.

<Production Example 5>
378 parts (1 mol) of the raw material nonionic surfactant [A] and 97.1 parts (1 mol) of sulfamic acid were reacted at 120 ° C. for 5 hours to obtain the product [1] of the present invention.

<Production Example 6>
Inventive product [2] [3] [4], Comparative product, in the same manner as in Production Example 5, except that the raw material nonionic surfactant [A] was changed to the raw material nonionic surfactant shown in Table 2 below. [1] to [3] were obtained.

<Production Example 7>
117 parts (1 mole) of chlorosulfonic acid was added dropwise to 876 parts (1 mole) of the raw material nonionic surfactant [D] cooled to 20 ° C. After the dropping, HCl generated by the reaction was sucked with a vacuum pump and neutralized with an aqueous sodium hydroxide solution to obtain the product [5] of the present invention.

<Production Example 8>
Raw material nonionic surfactant [E] 1029 parts (1 mol) and sodium monochloroacetate 117 parts (1 mol) were mixed at room temperature over 30 minutes, and the reaction vessel was kept at 40 ° C. to 44 parts of sodium hydroxide (1 0.1 mol) was added over 3 hours, and the mixture was further reacted at 40 ° C. for 17 hours. Next, after neutralizing with 75 wt% phosphoric acid, 400 mL of methylene chloride and 200 mL of water were added and washed with water. Further, after washing with 200 mL of water twice, methylene chloride in the organic layer was distilled off. Then, it neutralized to pH 8 with sodium hydroxide aqueous solution, and this invention product [7] was obtained.

<Production Example 9>
1024 parts (1 mol) of raw material nonionic surfactant [H] and 98 parts (1 mol) of maleic anhydride were reacted at 80 ° C. for 2 hours, and then 3000 parts of water was added and hydroxylated at 30 ° C. or less. Neutralized with aqueous sodium solution. Next, 104 parts (1.1 mol) of sodium hydrogen sulfite was added and reacted at 70 ° C. for 3 hours to obtain the product [8] of the present invention.

<Production Example 10>
945 parts (2.5 mol) of raw material nonionic surfactant [A] and 142 parts (1 mol) of phosphoric anhydride were reacted at 80 ° C. for 5 hours, and then neutralized with an aqueous sodium hydroxide solution. Product [9] was obtained.

<Production Example 11>
Except that the raw material nonionic surfactant [D] was changed to the raw material nonionic surfactant shown in Table 2 below, the product [6] of the present invention and the comparative product [4] [5] were prepared in the same manner as in Production Example 7. Got.

<Production Example 12>
A comparative product [6] was obtained in the same manner as in Production Example 9 except that the raw material nonionic surfactant [H] was changed to the raw material nonionic surfactant [M].

<Production Example 13>
A comparative product [7] was obtained in the same manner as in Production Example 8 except that the raw material nonionic surfactant [E] was changed to the raw material nonionic surfactant [N].

<Production Example 14>
A comparative product [8] was obtained in the same manner as in Production Example 10 except that the raw material nonionic surfactant [A] was changed to the raw material nonionic surfactant [I].

<Production Example 15>
A comparative product [9] was obtained in the same manner as in Production Example 7 except that the raw material nonionic surfactant [D] was changed to lauryl alcohol.

<Examples 1-5 and Comparative Examples 1-4>
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 134 parts of distilled water and 0.5 part of sodium bicarbonate as a buffering agent, heated to 80 ° C., and dissolved oxygen was added with nitrogen gas. Removed. Separately, 75 parts of styrene, 50 parts of methyl methacrylate, 121 parts of butyl acrylate, 4 parts of acrylic acid, 5 parts of emulsifier, and 110 parts of distilled water were mixed to prepare a monomer emulsion. Next, 40 parts of the monomer emulsion prepared above were added all at once to the reaction vessel, and after stirring for 10 minutes, 0.5 part of ammonium persulfate as a polymerization initiator was added and stirred for 10 minutes. Next, the remaining monomer emulsion was added dropwise over 3 hours to conduct a polymerization reaction, cooled to 40 ° C., and adjusted to pH 8-9 with aqueous ammonia to obtain a polymer emulsion. The emulsifiers used are as shown in Table 3 below.

  The resulting polymer emulsion was evaluated for polymerization stability, mechanical stability, particle size, particle size distribution, and film gloss. The evaluation method is as follows, and the results are shown in Table 3.

[Polymerization stability]
The polymer emulsion after polymerization was filtered using an 80 mesh filter cloth, and the residue on the filter cloth was washed with water and dried at 105 ° C. for 3 hours. The weight of the residue after drying was measured and expressed as a weight ratio (%) to the total solid content.

[Machine stability]
50 g of the polymer emulsion was measured with a Marlon tester (load: 10 kg, rotation speed: 1000 rpm, time: 5 minutes). The generated agglomerates were filtered through an 80-mesh wire mesh, and the residue was washed with water and dried at 105 ° C. for 3 hours. The weight was expressed as a weight ratio (%) to the total solid content.

[Particle size]
The particle size distribution was measured with a dynamic light scattering particle size distribution analyzer (MICROTRAC UPA 9340 manufactured by Nikkiso) and displayed in μm.

[Particle size distribution]
The standard deviation was obtained from the particle size distribution obtained by the dynamic light scattering particle size distribution measurement, and was expressed as a value obtained by dividing the standard deviation by the median diameter, that is, relative standard deviation (%).

[Glossiness of film]
A 0.5 mm (wet) emulsion film was formed on a glass plate and allowed to stand at room temperature for 18 to 20 hours to prepare a film. The glossiness of this film was visually evaluated in three stages: ○ (excellent), Δ (possible), and × (impossible).

<Examples 6-7 and Comparative Examples 5-7>
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 134 parts of distilled water and 0.5 part of sodium bicarbonate as a buffering agent, heated to 80 ° C., and dissolved oxygen was added with nitrogen gas. Removed. Separately, 171 parts of 2-ethylhexyl acrylate, 75 parts of ethyl acrylate, 4 parts of acrylic acid, 5 parts of emulsifier, and 110 parts of distilled water were mixed to prepare a monomer emulsion containing an emulsifier. Next, 40 parts of the monomer emulsion prepared above were added all at once to the reaction vessel, and after stirring for 10 minutes, 0.5 part of potassium persulfate as a polymerization initiator was added and stirred for 10 minutes. Next, the remaining monomer emulsion was added dropwise over 3 hours to conduct a polymerization reaction, cooled to 40 ° C., and adjusted to pH 8-9 with aqueous ammonia to obtain a polymer emulsion. The emulsifiers used are as shown in Table 4 below.

  The resulting polymer emulsion was evaluated for polymerization stability, particle size, and foamability. The evaluation method of foamability is as follows, and the other evaluation methods are the same as those in Example 1. The results are shown in Table 4.

[Bubbling]
At room temperature, 20 mL of polymer emulsion and 10 mL of water were placed in a 100 mL Nessler tube, foamed by shaking (15 times; once / 2 seconds), and displayed as the amount of foam (mL) after standing for 2 minutes.

<Examples 8 to 10 and Comparative Examples 8 to 10>
An autoclave was charged with 238 parts of distilled water, 1 part of ammonium persulfate, 6 parts of emulsifier, 3 parts of α-methylstyrene dimer, 1 part of t-dodecyl mercaptan, and 1 part of sodium bicarbonate, and the temperature was raised to 70 ° C. with nitrogen gas. Dissolved oxygen was removed. Next, 90 parts of butadiene, 120 parts of styrene, 35 parts of acrylonitrile and 5 parts of itaconic acid were separately introduced over 3 hours while maintaining the reaction solution at 70 ° C., and the reaction was carried out for 3 hours after the introduction was completed. Then, it cooled to 40 degreeC and adjusted to pH8-9 with the sodium hydroxide aqueous solution, and obtained the polymer emulsion. The used emulsifiers are as shown in Table 5 below.

  The resulting polymer emulsion was evaluated for polymerization stability and particle size. The evaluation method is the same as in Example 1 above. The results are shown in Table 5.

  As shown by the above examples and comparative examples, the emulsifier for emulsion polymerization of the product of the present invention has a degree of branching in a range in which the raw material alcohol is particularly limited, so that the polymerization stability and mechanical stability are good, and foaming Less polymer emulsion was obtained. Moreover, the glossiness of the film was also excellent.

  On the other hand, in the comparative product [3] having a branching degree of the raw material alcohol of less than 1.05, as shown in Comparative Example 5, the foaming of the polymer emulsion was large. Further, the comparative products [4] and [5] having a degree of branching greater than 1.5 were inferior in film gloss as shown in Comparative Examples 3 and 4.

Since the emulsifier of the present invention has the above-described excellent effects, it can be preferably used as an emulsifier for emulsion polymerization of various monomers, and is particularly a polymer emulsion that has less foaming and excellent film gloss. Therefore, it can be particularly preferably used as an emulsifier for emulsion polymerization of a polymer emulsion used for coating.

Claims (5)

It is an anionic surfactant represented by the following general formula (1), and an anionic surfactant (a) obtained from a nonionic surfactant having a branching degree of raw material alcohol of 1.05 to 1.50 is essential. An emulsifier for emulsion polymerization, characterized by comprising a component.
^{R 1 O- (A 1 O)} z-X (1)
(In the formula, R ¹ represents an alkyl group having a C 9-11 alkyl group content of 80 wt% or more, A ¹ O represents a C 2-4 oxyalkylene group, and z Is an integer of 1 to 50, X represents an anionic hydrophilic group, and the addition form of A ¹ O is random addition, block addition, or mixed addition thereof. The anionic surfactant (a) is an anionic surfactant represented by the following general formula (2), and an anionic surfactant obtained from a nonionic surfactant having a branching degree of the raw material alcohol of 1 ( b) and an anionic surfactant represented by the general formula (3), the anionic surfactant (c) obtained from a nonionic surfactant having a branching degree of the raw material alcohol of 2 as an essential component The emulsifier for emulsion polymerization according to claim 1, wherein the weight ratio of component (b) to component (c) is (b) / (c) = 50/50 to 95/5.
^{R 2 O- (A 2 O)} m-X (2)
^{R 3 O- (A 3 O)} n-X (3)
(In the formula, R ² and R ³ are alkyl groups having 9 to 11 carbon atoms and the alkyl group content is 80% by weight or more, and A ² O and A ³ O are carbon atoms having 2 to 4 carbon atoms. Represents an oxyalkylene group, m and n are integers of 1 to 50, and X represents an anionic hydrophilic group, and the addition form of A ² O and A ³ O is random addition, block addition, or mixed addition thereof. ) The anionic surfactants represented by the general formulas (1), (2), and (3) are derived from alcohols represented by the following general formula (4) obtained from the Guerbe reaction, and R ⁴ , R ⁵ is an emulsifier for emulsion polymerization according to claim 1 or 2, characterized in that a linear alkyl group or branched alkyl group.
R ⁴ —CH (R ⁵ ) —CH ₂ —OH (4) In the anionic surfactants (b) and (c), R ^{2 in the} general formula (2) is a 2-alkyl-1-alkanol having 10 carbon atoms, and R ^{3 in the} general formula (3) is 10 carbon atoms. The emulsifier for emulsion polymerization according to any one of claims 1 to 3, which is derived from 2-alkyl-4-alkyl-1-alkanol and / or 2-alkyl-5-alkyl-1-alkanol. The anionic surfactant has a group represented by any one of the following general formulas (5) to (9) as X in the general formulas (1) to (3). Item 5. The emulsifier for emulsion polymerization according to any one of Items 1 to 4.
X: —SO ₃ M (5)
-PO ₃ M ₂ (6)
-P (R ⁶ ) O ₂ (7)
-CH ₂ COOM (8)
—CO—CH ₂ —CH (SO ₃ M) COOM (9)
(In the formula, each M is independently a hydrogen, alkali metal, NH ₄ or alkanolamine residue, and R ⁶ is a residue excluding X in the general formulas (1) to (3).)