JP4542887B2 - Emulsifier for emulsion polymerization - Google Patents

Description

  The present invention relates to a novel emulsifier for emulsion polymerization, which suppresses the generation of aggregates, is excellent in polymerization stability, and has low foaming properties when producing a synthetic resin by emulsion polymerization. .

  Resin emulsions are widely used as paints, adhesives, paper processing agents, fiber processing agents, and the like, and emulsion polymerization methods are often used as their production methods. Since the resin emulsion obtained by the emulsion polymerization method uses water as a solvent, industrial importance is increasing from the viewpoints of environmental protection and work safety. Against this background, for example, in the paint industry, the transition from solvent-based paints to water-based emulsion paints is rapidly progressing.

  Examples of the emulsifier for emulsion polymerization used in the emulsion polymerization method include nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether, alkylbenzene sulfonate, polyoxyethylene alkylsulfate, polyoxyethylene Examples include anionic surfactants such as ethylene alkylphenyl sulfate ester salts and higher fatty acid salts. These emulsifiers for emulsion polymerization are indispensable for smoothly proceeding emulsion polymerization and suppressing the formation of aggregates. However, the emulsifier remaining in the produced emulsion causes foaming. Causes adverse effects such as pinholes. For this reason, there is a high demand for low foaming emulsifiers for emulsion polymerization, and styrenated phenol types (for example, Patent Document 1), emulsifiers having a specific molecular weight distribution (for example, Patent Document 2), and the like have been proposed.

Among the above-mentioned emulsifiers for emulsion polymerization, ether-type nonionic surfactants obtained by adding alkylene oxides such as ethylene oxide to nonylphenol, or anionic surfactants obtained by sulfate esterification of these are the generation of aggregates. It is used in a wide range because it has characteristics such as low polymerization and good polymerization stability. However, since nonylphenol is suspected of being an environmental hormone (endocrine disrupting substance), some manufacturers have stopped producing it, and there is concern about supply insecurity in Japan. Under such circumstances, an industry that wants to convert an ether type nonionic surfactant obtained by adding alkylene oxide such as ethylene oxide to nonylphenol or an anionic surfactant obtained by sulfate-converting it to other compounds Of a hydrogenated alkylphenol as a raw material (for example, Patent Document 3), an aliphatic alcohol alkylene oxide adduct having a specific composition or molecular weight distribution (for example, Patent Documents 4 and 5), Many proposals have been made using unsaturated alcohol as a raw material (for example, Patent Document 6), but there is no one that still satisfies the performance.
JP-A-8-113602 (1-7) Japanese Patent Laid-Open No. 2001-300283 (1-13) JP 2000-344807 (1-4) JP2001-011489 (1-18) JP 2001-072703 (1-10) JP-A-2004-002644 (1-12)

  An object of the present invention is to produce an ether type nonionic surfactant obtained by adding an alkylene oxide such as ethylene oxide to nonylphenol or an anionic surfactant obtained by subjecting this to a sulfate ester in producing a synthetic resin by emulsion polymerization. It is an object to provide a novel emulsifier for emulsion polymerization having the same aggregate generation amount and polymerization stability as those of the present invention, and having a low foaming property.

  As a result of diligent research to solve the above problems, the present inventors have used an emulsifier having cumylphenol as a skeleton for emulsion polymerization, whereby an ether-type non-oxide having an alkylene oxide such as ethylene oxide added to nonylphenol. An ionic surfactant or an anionic surfactant obtained by subjecting it to a sulfate ester, has the same aggregate generation amount, polymerization stability, and low foaming properties, and has reached the present invention. It is.

（但し、Ａは炭素数２〜４のアルキレン基であり、ｎは０〜１００の整数、Ｘは水素原子、アニオン性親水基またはその塩を表す。）で示される乳化重合用乳化剤である。 That is, the present invention provides the following general formula (1)

(Wherein A is an alkylene group having 2 to 4 carbon atoms, n is an integer of 0 to 100, and X is a hydrogen atom, an anionic hydrophilic group or a salt thereof).

  By using the emulsifier for emulsion polymerization of the present invention, an ether-type nonionic surfactant obtained by adding an alkylene oxide such as ethylene oxide to nonylphenol or an aggregate equivalent to an anionic surfactant obtained by subjecting this to a sulfate ester A resin emulsion having a generation amount, polymerization stability, and low foamability can be obtained.

Hereinafter, the present invention will be described in detail.
The — (AO) _n — part in the general formula (1) represents a polyoxyalkylene chain obtained by addition polymerization of ethylene oxide, propylene oxide or butylene oxide. Effectively, only ethylene oxide is preferable. In the case of a copolymer containing propylene oxide or / and butylene oxide, the molar ratio of propylene oxide or / and butylene oxide is preferably 30% or less. The copolymerization method does not change whether it is random or block.
The polymerization number n is in the range of 0 to 100, but when X in the general formula (1) is a hydrogen atom, n = 5 to 70 is effectively effective, and more preferably n = 10 to 60. It is a range. Moreover, when X in the general formula (1) is an anionic hydrophilic group or a salt thereof, n = 0 to 30 is preferable, and n = 5 to 20 is more preferable.

X in the general formula (1) represents a hydrogen atom, an anionic hydrophilic group or a salt thereof, and the anionic hydrophilic group is a sulfate group represented by —SO ₃ M, —PO ₃ M ₂ or> PO _2. Examples thereof include a phosphate group represented by M. When the sulfate ester group and the phosphate ester group are compared, the phosphate ester group is more excellent in low foaming property and excellent in hydrolysis resistance, so that it can be preferably used even on the acidic side. M represents a hydrogen atom, a metal atom, ammonium or substituted ammonium, the metal atom is an alkali metal atom such as lithium, sodium, potassium or the like, the alkaline earth metal is calcium, magnesium, barium or the like, and the substituted ammonium is Examples include alkyl ammonium, alkanol ammonium, alkanol alkyl ammonium, and heterocyclic ammonium.

  The emulsifier for emulsion polymerization according to the present invention is easily obtained, for example, by adding alkylene oxide to cumylphenol using a known method and anionizing such as sulfate esterification or phosphate esterification as necessary. be able to.

  Examples of monomers applicable to emulsion polymerization using the emulsifier for emulsion polymerization according to the present invention include acrylic acid, methyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, 2-hydroxyethyl methacrylate, acrylonitrile, acrylamide, and the like. Acrylic monomers, aromatic monomers such as styrene, and olefin monomers such as ethylene, butadiene, chloroprene, vinyl chloride, and vinylidene chloride, but are not limited to these monomers.

  As the polymerization initiator, known polymerization initiators such as potassium persulfate, ammonium persulfate, hydrogen peroxide, azobisisobutyronitrile, benzoyl peroxide and the like can be used. Moreover, you may perform redox polymerization using reducing substances, such as sodium hydrogen sulfite, sodium thiosulfate, and ferrous sulfate.

  The amount of the emulsifier for emulsion polymerization according to the present invention varies depending on the monomer type and polymerization conditions, but is usually in the range of 0.1 to 10% by weight based on the total monomers, and is effective and economically 0.3. A range of ˜5% by weight is preferred. Further, other anionic emulsifiers, nonionic emulsifiers and various stabilizers may be used in combination.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example, unless the meaning is exceeded.
I. Synthesis example Synthesis example (1)
After 212 g (1 mol) of cumylphenol and 0.65 g of potassium hydroxide were charged into an autoclave and purged with nitrogen, the temperature was raised to 150 ° C., and 440 g (10 mol) of ethylene oxide was added. The ethylene oxide adduct 652g and sulfamic acid 97 g (1 mole) of stirrer, reflux condenser, transferred into a four-necked flask equipped with a thermometer and reacted for 5 hours at 120 ° C., sulfuric ester type Reference Example emulsification An emulsifier for polymerization (1) was obtained.

According to Synthesis Example (1), the emulsifiers for emulsion polymerization (2) and (4) of the present invention and the emulsifiers for emulsion polymerization (3) and (5) of Reference Examples were obtained. Details are shown in Table 1.

About the emulsifier for emulsion polymerization of the present invention and the reference example described above, foamability was measured according to the following evaluation method. The results are shown in Table 2.
Foam evaluation method: 50 mL of an emulsifier aqueous solution diluted to 1.0% was placed in a 100 mL graduated cylinder with a stopper, shaken for 20 seconds, and evaluated by the amount of foam after standing.

Comparative emulsifiers (6) to (10)
As a comparative control, comparative emulsifier (6) sodium poly (10 mol) oxyethylene nonylphenyl ether sulfate, comparative emulsifier (7) poly (9 mol) sodium oxyethylene nonylphenyl ether sodium phosphate, comparative emulsifier (8) poly (40 mol) Oxyethylene nonyl phenyl ether, comparative emulsifier (9) poly (10 mol) sodium oxyethylene lauryl ether sulfate, comparative emulsifier (10) poly (13 mol) oxyethylene distyryl phenyl ammonium sulfate are the same as the emulsifier for emulsion polymerization of the present invention. The foamability was evaluated. The results are shown in Table 2.

II. Example
Reference example (A-1)
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 430 g of ion-exchanged water and 6.0 g of emulsifier for emulsion polymerization (1) of the reference example shown in Table 1, and the system was replaced with nitrogen gas. did. Separately, 150 g (1.50 mol) of methyl methacrylate and 150 g (1.17 mol) of butyl acrylate were mixed, and 60 g of this mixed monomer was reacted with 0.60 g (4.1 × 10 ⁻³ mol) of ammonium persulfate. In addition to the container, the temperature was raised to 80 ° C. to carry out prepolymerization. From 10 minutes after the start of the prepolymerization, the remaining mixed monomer was added dropwise over 3 hours, and further aged at the same temperature for 1 hour to obtain a resin emulsion.
About the obtained resin emulsion, the amount of aggregates, solid content, foamability, and stability over time were measured according to the following evaluation methods. The results are shown in Table 3.

Description of evaluation method Aggregate amount: The resin emulsion after emulsion polymerization is filtered through a 200-mesh nylon cloth, and the weight of the residue after drying is evaluated in terms of% by weight based on the total monomers.
Solid content: About 1 g of the resin emulsion was weighed into an aluminum cup, and the weight after drying for 2 hours with a dryer at 105 ° C. was evaluated in terms of% by weight relative to the resin emulsion before drying.
Foaming property: The resin emulsion was diluted 2-fold with ion-exchanged water, placed in a 100 mL graduated cylinder with a stopper, shaken for 20 seconds, and evaluated by the amount of foam after standing.
Stability over time: The resin emulsion was placed in a 100 mL glass container, sealed and stored at 25 ° C., and the separation state of the resin emulsion was visually confirmed.
○: No separation △; Some separation ×: Clear separation

Examples (A-2) and (A-4) and Reference Examples (A-3) and (A-5)
The emulsifiers for emulsion polymerization (2) and (4) of the present invention shown in Table 1 and the emulsifiers for emulsion polymerization of reference examples (3) and (5) were also treated in the same manner as in Reference Example (A-1). An emulsion was prepared and the same evaluation method was performed. The results are shown in Table 3.

Comparative examples (a-1) to (a-5)
As comparative controls, the comparative emulsifiers (6) to (10) were subjected to emulsion polymerization and evaluation by the same method as in Example (A-1). The results are shown in Table 3 as Comparative Examples (a-1) to (a-5).

Reference example (B-1)
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 430 g of ion-exchanged water and 6.0 g of emulsifier for emulsion polymerization (1) of the reference example shown in Table 1, and the system was replaced with nitrogen gas. did. Separately, methyl methacrylate 156 g (1.56 mol), butyl acrylate 126 g (9.84 × 10 ⁻¹ mol), 2-hydroxyethyl methacrylate 15.0 g (1.15 × 10 ⁻¹ mol), methacrylic acid 3 0.0 g (3.5 × 10 ⁻² mol) was mixed, 60 g of this mixed monomer and 0.60 g (4.1 × 10 ⁻³ mol) ammonium persulfate were added to the reaction vessel, and the temperature was raised to 80 ° C. And prepolymerized. From 10 minutes after the start of the prepolymerization, the remaining mixed monomer was added dropwise over 3 hours, and further aged at the same temperature for 1 hour to obtain a resin emulsion.
About the obtained resin emulsion, evaluation similar to Reference Example (A-1) was performed. The results are shown in Table 4.

Examples (B-2) and (B-4) and Reference Examples (B-3) and (B-5)
The emulsifiers for emulsion polymerization (2) and (4) of the present invention shown in Table 1 and the emulsifiers for emulsion polymerization of reference examples (3) and (5) were also treated in the same manner as in Reference Example (B-1). An emulsion was prepared and the same evaluation method was performed. The results are shown in Table 4.

Comparative examples (b-1) to (b-5)
As a comparative control, the comparative emulsifiers (6) to (10) were subjected to emulsion polymerization and evaluation in the same manner as in Example (B-1). The results are shown in Table 4 as Comparative Examples (b-1) to (b-5).

Claims (2)

The following general formula (1)

(However, A is a C2-C4 alkylene group, n is an integer of 0-30, m is 1 or 2, M represents a hydrogen atom, a metal atom, ammonium, or substituted ammonium). Emulsifier for polymerization. A method for producing a resin emulsion, comprising subjecting an unsaturated monomer to emulsion polymerization in the presence of an emulsifier for emulsion polymerization according to claim 1.