JP2007277519A - Method for producing fine methacrylic resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of producing fine methacrylic resin particles by starting polymerization by a polymerization initiator while suspending a monomer containing methyl methacrylate as a main component into an aqueous medium by efficiently stirring the monomer together with the aqueous medium by using a polymerization container equipped with a stirring blade and polymerizing the monomer without causing aggregation. <P>SOLUTION: The method for producing fine methacrylic resin comprises polymerizing the monomer in the presence of a straight-chain saturated hydrocarbon represented by the formula (I): C<SB>m</SB>H<SB>2m+2</SB>and reducing stirring power (P) halfway during polymerization to ≤1/3 based on initial stirring power (P0) set when starting polymerization. In the production method, ≥75 mass% polymerization initiator is preferably a compound represented by formula (II) and the straight-chain saturated hydrocarbon is preferably used in an amount of 0.1-10 pts.mass and the polymerization initiator is preferably used in an amount of 0.01-5 pts.mass based on 100 pts.mass monomer and stirring power is preferably set within the above range while rate of polymerization of the monomer is ≤25%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing fine methacrylic resin particles.

For example, a polymerization vessel (2) equipped with a stirring blade (1) as shown in FIG. 1 is used, and a monomer mainly composed of methyl methacrylate is stirred together with an aqueous medium in the polymerization vessel (2). Thus, the so-called suspension polymerization method in which the polymerization is initiated and polymerized by the polymerization initiator while being suspended in the aqueous medium is widely used as a method for producing methacrylic resin particles. In this suspension polymerization method, it is known that when the stirring power is increased, the particle diameter of the resulting methacrylic resin particles is reduced.

However, for example, when trying to obtain fine methacrylic resin particles having an average particle diameter of 50 μm or less and polymerizing while stirring with high stirring power, the produced resin particles are intensively aggregated with each other, making it difficult to produce fine methacrylic resin particles. There was a problem of becoming.

Non-Patent Document 1 ["Emulsification / Dispersion Process Functions and Applied Technology", Science Forum, Inc., 1995, p. 38] describes a method for producing fine polymer particles without causing severe aggregation. A method is disclosed in which a monomer is suspended as fine droplets of about 1 μm in an aqueous medium using an emulsifier such as a homogenizer or a colloid mill, then transferred to a polymerization vessel, and a polymerization initiator is added for polymerization. However, the mixture of the monomer and the aqueous medium must be transferred to the polymerization vessel after being suspended, and is not necessarily an efficient production method.

"Functions and applied technologies of emulsification and dispersion processes", Science Forum, Inc., 1995, p. 38 Mixing Principles and Applications, pp24-44, (by Shinji Nagata; KODANSHA A HALSTED PRESS BOOK)

Therefore, the present inventor has intensively studied to develop a method capable of efficiently producing fine methacrylic resin particles using a polymerization vessel equipped with a stirring blade without causing aggregation, resulting in the present invention.

That is, in the present invention, a monomer containing methyl methacrylate as a main component is stirred together with an aqueous medium to suspend the monomer in the aqueous medium, and then the polymerization is initiated by the polymerization initiator and polymerized to obtain fine methacrylic resin particles. A process for the production of formula (I)

C _m H _{2m + 2} (I)

[In formula, m shows the integer of 12-26. ]

The monomer is polymerized in the presence of the linear saturated hydrocarbon represented by the formula, and the stirring power (P) is set to 1 during the polymerization with respect to the initial stirring power (P ₀ ) when the polymerization is started. The present invention provides a method for producing fine methacrylic resin particles characterized by having a range of / 3 times or less.

According to the production method of the present invention, fine methacrylic resin particles having an average particle diameter of 50 μm or less, preferably 20 μm or less, and usually 1 μm or more can be easily produced without causing severe aggregation.

The monomer used in the production method of the present invention is mainly composed of methyl methacrylate. For example, the total amount of the monomer, that is, 100% by mass may be methyl methacrylate, or 50% by mass or more. Preferably 80% by mass or more, more preferably 90% by mass or more is methyl methacrylate, 50% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less is a monomer that can be copolymerized with methyl methacrylate. It may be. The monomer that can be copolymerized may be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, or may be a polyfunctional monomer having two or more. .

Examples of monofunctional monomers that can be copolymerized with methyl methacrylate include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, Acrylic acid esters such as hydroxybutyl acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and other methacrylic acid esters Nitrogen-containing acrylic monomers such as acrylamide and acrylonitrile, methacrylamide, nitrogen-containing methacrylic monomers such as tolyl and methacryloyl, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, styrene, α-methylstyrene, etc. Aromatic vinyl monomers, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride.

Examples of the polyfunctional monomer copolymerizable with methyl methacrylate include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, tetramethylol methane triacrylate, tetramethylol methane triacrylate, acrylic acid ester of polyhydric alcohol such as tetramethylol methane tetraacrylate, ethylene glycol Dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylol Examples include methacrylic acid esters of polyhydric alcohols such as methanetrimethacrylate and tetramethylolmethanetetramethacrylate, allyl methacrylate, divinylbenzene, diallyl phthalate, and the like.

These monofunctional monomers and polyfunctional monomers are used alone or in combination of two or more.

Water is usually used as the aqueous medium, but it may contain an organic solvent as long as it can be polymerized in a state where the monomer is suspended. The amount of the aqueous medium used is an amount capable of suspending the monomer by stirring, and is usually 1 mass times or more with respect to the monomer, and is usually 10 mass times or less, preferably 5 mass times in terms of volumetric efficiency. Is less than double.

A suspension stabilizer may be contained in the aqueous medium. Suspension stabilizers include, for example, polymer dispersants such as sodium polymethacrylate, methylcellulose, polyvinyl alcohol, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium alkyldiphenylether disulfonate Nonionic surfactants such as anionic surfactants such as polyoxyethylene polyoxypropylene ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether, polyoxyethylene myristyl ether Surfactants, sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium sulfate, etc. Such as aircraft salts. The amount of the suspension stabilizer used is usually 0.005 parts by mass or more per 100 parts by mass of water in that the monomer is easily suspended as droplets in an aqueous medium. Usually, it is in the range of 10 parts by mass in that an effect commensurate with the amount can be obtained. The suspension stabilizer may be added before the start of polymerization or may be added after the start of polymerization.

In order to stir the monomer together with the aqueous medium, a polymerization vessel (2) equipped with a stirring blade (1) as shown in FIGS. 1 and 2 is usually used.

As the stirring blade (1), one attached to the stirring shaft (11) is used. The stirring blade (1) rotates the stirring shaft (11) as a rotating shaft, thereby stirring the polymerization mixture (3) in the polymerization vessel (2). The shape of the stirring blade (1) is not particularly limited as long as the polymerization mixture (3) being polymerized can be sufficiently stirred, and is used in a usual suspension polymerization method such as a turbine blade, a Faudler blade, a propeller blade, or the like. A stirring blade can be used. The stirring blade (1) rotates by rotating the stirring shaft (11) with an electric motor (not shown) or the like, and stirs the polymerization mixture (3). The diameter (d) of the stirring blade (1) is usually in the range of 0.04 m to 4 m.

As the polymerization vessel (2), for example, a cylindrical polymerization vessel whose inner surface (2a) has a cylindrical shape can be used. The inner diameter (D) of the polymerization vessel is usually about 0.1 to 5 m. Usually, the diameter (d) of the stirring blade is about 0.4 to 0.8 times the inner diameter (D) of the polymerization vessel. It is a range. The polymerization vessel (2) may be provided with a baffle (4) so that the polymerization mixture (3) being polymerized is sufficiently mixed. The shape of the baffle (4) can be a plate shape or a rod shape. When baffles are provided, the number thereof is appropriately selected according to the volume of the polymerization vessel and may be one, but usually two or more are provided for sufficient mixing, and the number is 8 or less. Is preferred. In the polymerization container shown in FIGS. 1 and 2, six plate-like baffles (4) are provided along the inner surface of the polymerization container.

The monomer and the aqueous medium are put into the polymerization vessel (2), and the stirring is performed by rotating the stirring blade (1), whereby the polymerization is started while suspending the monomer in the aqueous medium. At the start of polymerization is usually 0.05 kW / m ³ or higher, preferably 0.1 kW / m ³ or more, usually stirred at 3 kW / m ³ or less of the initial stirring power (P _0).

Polymerization can be started, for example, by adding a polymerization initiator in advance to the monomer and the aqueous medium and heating to the polymerization temperature while stirring, as in the case of ordinary suspension polymerization.

As the polymerization initiator, those which can be used for polymerization by a usual suspension polymerization method can be used, and preferably the formula (II)

[In formula, p and q show the integer of 6-12 each independently. ]

It is a compound shown by these. Examples of the compound represented by the above formula (II) include dilauroyl peroxide [a compound in which p and q in the formula (II) both correspond to 10. ] Didecanoyl peroxide [a compound in which p and q in formula (II) both correspond to 8. ], Preferably dilauroyl peroxide.

When using the compound shown by Formula (II), it is preferable that the usage-amount is 50 mass% or more of a polymerization initiator, More preferably, it is 75 mass% or more.

Examples of the polymerization initiator other than the compound represented by the formula (II) include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, dimethyl- Examples thereof include azo polymerization initiators such as 2,2′-azobisisobutyrate and peroxide polymerization initiators such as benzoyl peroxide and tert-butyl-peroxy-2-ethylhexanoate.

The usage-amount of a polymerization initiator is 0.01 mass part-5 mass parts normally per 100 mass parts of monomers, Preferably it is 1 mass part or less.

The polymerization temperature is equal to or higher than the thermal decomposition start temperature of the polymerization initiator, and is usually 60 ° C to 120 ° C.

In the production method of the present invention, the monomer is polymerized in the presence of the linear saturated hydrocarbon represented by the above formula (I). Examples of the linear saturated hydrocarbon represented by the formula (I) include dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane, and hexacosane. M is 20 or more, more preferably docosane.

The amount of the linear saturated hydrocarbon represented by the formula (I) is usually 0.1 parts by mass or more per 100 parts by mass of the monomer, and is usually in that the physical properties of the resulting fine methacrylic resin particles are not impaired. It is 10 parts by mass or less, preferably 5 parts by mass or less.

By continuing the stirring after the polymerization is started, the polymerization proceeds while the monomer is in a suspended state. In the production method of the present invention, the stirring power (P) during the polymerization is The initial stirring power (P ₀ ) is 1/3 times or less, usually 1/400 or more. The stirring power can be determined by a method described in, for example, Non-Patent Document 2 [Mixing Principles and Applications, pp24-44, (by Shinji Nagata; KODANSHA A HALSTED PRESS BOOK)].

In order to set the stirring power (P) within the above range, for example, the rotation of the stirring blade (1) may be decelerated to reduce the rotational speed (n). The tip speed (V) of the stirring blade (1) after deceleration is expressed by the equation (1)

  V = π × d × n (1)

[In the formula, π represents the circumference, d represents the diameter of the stirring blade (unit: m), and n represents the rotational speed of the stirring blade after deceleration (unit: second ^-1 ). ]

Indicated by The tip speed (V) is expressed by equation (2)

V ≦ V ₀ × 2.3 × D / 10 ^d (2)

[In the formula, V represents the tip speed of the stirring blade after deceleration (unit: m / second), V ₀ represents the tip speed of the stirring blade when polymerization started (unit: m / second), and D represents polymerization. The inner diameter of the container (unit: m), d and n have the same meaning as above. ]

However, in the production method of the present invention, the tip speed (V) of the stirring blade after deceleration does not satisfy the formula (2), and the formula (3)

V> V ₀ × 2.3 × D / 10 ^d (3)

[Wherein, V, V ₀ , D and d each have the same meaning as described above. ]

Even when the above is satisfied, the desired fine methacrylic resin particles can be obtained.

In the production method of the present invention, the stirring power (P) is set to the above range during the polymerization, preferably while the polymerization rate of the monomer is 25% or less, more preferably 20% or less. The polymerization rate when the stirring power (P) is within the above range may exceed 0%, and may be immediately after the start of polymerization. In addition, the polymerization rate of a monomer is the ratio of the monomer which superposed | polymerized among the used monomers.

After the stirring power (P) is in the above range, the polymerization is usually completed while stirring with the stirring power in this range. In order to complete the polymerization, the polymerization temperature may be maintained as it is and the polymerization proceeds with stirring. Depending on the polymerization temperature, an unpolymerized monomer may remain. In this case, the polymerization may be completed by raising the temperature within the above-described polymerization temperature range.

The target fine methacrylic resin particles can be taken out by solid-liquid separation of the polymerization mixture after completing the polymerization in the same manner as usual. Examples of the method for solid-liquid separation include the same methods as usual, such as a method by filtration such as natural filtration, centrifugal filtration, and pressure filtration, and a method of centrifugal sedimentation using a decanter, a cyclone, and the like. The extracted fine methacrylic resin particles may be washed with water or the like. The obtained fine methacrylic resin particles may be completely dried, but in order to prevent electrostatic charging, it is preferable to store in a state containing 5 parts by mass or more of water per 100 parts by mass of the methacrylic resin particles. .

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.

The polymerization rate during polymerization was determined from the amount of change in mass when a sample collected from the polymerization mixture during polymerization was dried at 110 ° C. for 2 hours.

The initial stirring power (P ₀ ) and stirring power (P) are determined according to Non-Patent Document 2 [Mixing Principles and Applications, pp24-44, (by Shinji Nagata; KODANSHA A HALSTED PRESS BOOK)]. The density (ρ) was 983 Kg / m ³ and the viscosity (μ) was 3.97 mPa · s.

The center particle diameter (D50) of the obtained fine methacrylic resin particles was determined by dispersing the fine methacrylic resin particles in pure water and irradiating with ultrasonic waves, followed by a light scattering particle size measuring device (“FRA” manufactured by Micro Track). It measured using.

Presence or absence of aggregation was determined by collecting the polymer slurry after polymerization on a slide glass and observing it with an optical microscope at a magnification of 100 times.

As shown in FIG. 1 and FIG. 2, a polymerization vessel (2) having a cylindrical shape and a cooler (not shown) with an internal volume of 2 dm ³ (2 L) and an inner diameter (D) of 0.13 m was used. . Inside, six plate-like baffles (4) having a width of 7 mm and extending upward from the bottom surface (2b) along the inner surface (2a) of the container were provided at equal intervals. The polymerization vessel (2) is provided with a stirring blade (1) attached to the stirring shaft (11). As the stirring blade (1), a rectangular flat plate having a width of 14 mm was used, which was attached at a mounting angle (θ) of 45 ° with respect to the stirring shaft (11) as shown in FIG. The number of stirring blades (1) was eight, and four blades were attached in two stages. The diameter (d) of the stirring blade (1) was 0.06 m.

Example 1
In a polymerization vessel (2), 1015 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.369 g of poly (sodium methacrylate) [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.22 g of “Pluronic F68” manufactured by Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 391.8 g of methyl methacrylate, 16.9 g of methyl acrylate [monofunctional monomer], 2.53 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], 8.43 g of docosan, A mixture of 1.26 g of dilauroyl peroxide [polymerization initiator] and 0.42 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 75% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 75% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.3 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.29 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 250 rpm (4.17 sec ⁻¹ ). At this time, the stirring power (P) is 0.0109 kW / m ³ and the tip speed (V) is 0.785 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 12.3%, and when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 12.3%.

Thereafter, polymerization was performed at the same temperature and rotation speed under a nitrogen gas flow. As a result, the internal temperature rapidly increased due to heat generation during the polymerization, and the internal temperature increased to about 73 ° C. After the end of heat generation, when the internal temperature is cooled to 65 ° C. by cooling, the temperature is further raised to complete the polymerization by setting the internal temperature to 85 ° C., and fine methacrylic resin particles having a center particle diameter (D50) of 12.5 μm are obtained. Obtained. In addition, aggregation was not seen by the fine methacryl resin particle in the slurry-like polymerization mixture after superposition | polymerization. The results are shown in Table 1.

Example 2
In a polymerization vessel (2), 1013 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.21 g of “Pluronic F68” manufactured by Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 396.5 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.52 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization modifier], 1.68 g of docosan, A mixture of 2.52 g of dilauroyl peroxide [polymerization initiator] and 0.42 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 82% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 82% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.31 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.25 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 250 rpm (4.17 sec ⁻¹ ). At this time, the stirring power (P) is 0.0109 kW / m ³ and the tip speed (V) is 0.785 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 17.4%, so when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 17.4%.

Thereafter, the same operation as in Example 1 was performed to complete the polymerization, and fine methacrylic resin particles were obtained. The results are shown in Table 1.

Example 3
In a polymerization vessel (2), 1012 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.20 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, methyl methacrylate 394.4 g, methyl acrylate [monofunctional monomer] 16.8 g, ethylene glycol dimethacrylate [polyfunctional monomer] 2.52 g, terpinolene [polymerization modifier] 0.063 g, docosan 1.68 g, A mixture of 4.20 g of dilauroyl peroxide [polymerization initiator] and 0.42 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Moreover, 91 mass% of polymerization initiators are dilauroyl peroxide, and the ratio (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 91 mass%.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.40 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.22 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec.
Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 24.7%, and when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 24.7%.

Thereafter, the same operation as in Example 1 was performed to complete the polymerization, and fine methacrylic resin particles were obtained. The results are shown in Table 1.

Example 4
In a polymerization vessel (2), 1012 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.20 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 396.2 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.52 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization modifier], 2.24 g of docosan, A mixture in which 2.52 g of dilauroyl peroxide [polymerization initiator] was mixed was added and bubbled with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 100% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.40 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.22 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 370 rpm (6.17 sec ⁻¹ ). The stirring power (P) at this time is 0.0352 kW / m ³ and the tip speed (V) is 1.16 m / sec.
Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 19.4%, so when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 19.4%.

Thereafter, the same operation as in Example 1 was performed to complete the polymerization, and fine methacrylic resin particles were obtained. The results are shown in Table 1.

Comparative Example 1
Place 1014 g of ion-exchanged water in the polymerization vessel (2) at room temperature [about 20 ° C.], then 0.368 g of poly (sodium methacrylate) [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.21 g of “Pluronic F68” manufactured by Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Further, 399.7 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.53 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], dilauroyl peroxide [ A mixture of 1.26 g of polymerization initiator] and 0.42 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 75% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 75% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.32 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.25 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 250 rpm (4.17 sec ⁻¹ ). At this time, the stirring power (P) is 0.0109 kW / m ³ and the tip speed (V) is 0.785 m / sec.

Thereafter, the same operation as in Example 1 was carried out. As a result, intense aggregation occurred during the polymerization, and fine methacrylic resin particles could not be obtained. The results are shown in Table 1.

Comparative Example 2
In a polymerization vessel (2), 1013 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.21 g of “Pluronic F68” manufactured by Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Further, 399.7 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.52 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization modifier], dilauroyl peroxide [ A mixture of 2.52 g of polymerization initiator] and 0.32 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 89% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 89% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.31 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.24 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 250 rpm (4.17 sec ⁻¹ ). At this time, the stirring power (P) is 0.0109 kW / m ³ and the tip speed (V) is 0.785 m / sec. Further, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 19.7%, and when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 19.7%.

Thereafter, the same operation as in Example 1 was performed to complete the polymerization, and fine methacrylic resin particles were obtained. The results are shown in Table 1.

Comparative Example 3
In a polymerization vessel (2), 1012 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.20 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 396.1 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.52 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], dilauroyl peroxide [ A mixture of 4.20 g of polymerization initiator and 0.32 g of benzoyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 93% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 93% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.40 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.21 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 26.3%, and when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 26.3%.

Thereafter, the same operation as in Example 1 was performed to complete the polymerization, and fine methacrylic resin particles were obtained. The results are shown in Table 1.

Comparative Example 4
In a polymerization vessel (2), 1013 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.368 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.21 g of “Pluronic F68” manufactured by Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 398.7 g of methyl methacrylate, 16.8 g of methyl acrylate [monofunctional monomer], 2.52 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], dilauroyl peroxide [ Polymerization initiator] A mixture mixed with 2.52 g was added and bubbled with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, 100% by mass of the polymerization initiator is dilauroyl peroxide, and the proportion of dilauroyl peroxide in the polymerization initiator (LPO ratio) is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.31 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.25 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. The solution was added. Further, when 18 minutes had passed since the time when the internal temperature reached 60 ° C., the rotation of the stirring blade (1) was decelerated and the rotation speed (n) was set to 370 rpm (6.17 sec ⁻¹ ). The stirring power (P) at this time is 0.0352 kW / m ³ and the tip speed (V) is 1.16 m / sec.
Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 16.3%, so when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 16.3%.

Thereafter, the same operation as in Example 1 was carried out. As a result, intense aggregation occurred during the polymerization, and fine methacrylic resin particles could not be obtained. The results are shown in Table 1.

Comparative Example 5
In a polymerization vessel (2), 1002 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.364 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.16 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.083 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 372.0 g of methyl methacrylate, 16.6 g of methyl acrylate [monofunctional monomer], 2.50 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.062 g of terpinolene [polymerization regulator], 22.2 g of docosane and A mixture in which 2.50 g of dilauroyl peroxide [polymerization initiator] was mixed was added and bubbled with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 65 ° C. at a rate of temperature rise of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.32 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 24.97 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. Solution was added.

Thereafter, polymerization was carried out at the same temperature and rotation speed under a nitrogen gas flow. As a result, severe aggregation occurred during the polymerization, and fine methacrylic resin particles could not be obtained. The results are shown in Table 1.

Table 1
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
LPO ratio Docosan Power ratio (P / P ₀ ) Polymerization rate Aggregation D50
(Mass%) (parts by mass ^{* 1} ) (-) (%) presence / absence (μm)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Example 1 75 2 0.037 <12.3 None 12.5
Example 2 86 0.4 0.037 <17.4 None 11.7
Example 3 91 0.4 0.093 <24.7 None 13.0
Example 4 100 0.5 0.12 <19.4 None 14.6
Comparative Example 1 80 0 0.037-Yes-
Comparative Example 2 89 0 0.037 <19.7 Yes 15.0
Comparative Example 3 93 0 0.093 <26.3 Yes 13.0
Comparative Example 4 100 0 0.12 <16.3 Yes-
Comparative Example 5 100 5.7 1-Yes-
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
* 1: The use amount of docosane is shown by the use amount (mass part) per 100 parts by mass of the monomer.

Example 5
The polymerization vessel (2) was charged with 975.5 g of ion-exchanged water at room temperature [about 20 ° C.], then 0.367 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, 4.19 g of “Pluronic F68” manufactured by Asahi Denka Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 315.7 g of methyl methacrylate, 83.8 g of styrene, 4.2 g of methyl acrylate [monofunctional monomer], 3.35 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], A mixture of 6.29 g of docosan and 5.87 g of dilauroyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 75 ° C. at a temperature rise rate of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, based on the time when the internal temperature reached 60 ° C., 8.38 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was ionized at the time when 3 minutes passed and when 100 minutes passed. A solution dissolved in 25.16 g of exchange water was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 24.9%, and when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 24.9%.

Thereafter, polymerization was carried out at the same temperature and rotation speed under a nitrogen gas flow. As a result, a rapid increase in internal temperature due to heat generation was observed during the polymerization, and the internal temperature rose to about 82 ° C. After the end of heat generation, when the internal temperature was cooled to 75 ° C. by cooling, the temperature was further raised to complete the polymerization by setting the internal temperature to 85 ° C., and fine methacrylic resin particles having a center particle diameter (D50) of 17.2 μm were obtained. Obtained. In addition, aggregation was not seen by the fine methacryl resin particle in the slurry-like polymerization mixture after superposition | polymerization. The results are shown in Table 2.

Example 6
In a polymerization vessel (2), 975.9 g of ion-exchanged water was added at room temperature (about 20 ° C.), then 0.367 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, 4.19 g of “Pluronic F68” manufactured by Asahi Denka Kogyo Co., Ltd. and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 318.4 g of methyl methacrylate, 83.8 g of styrene, 4.2 g of methyl acrylate [monofunctional monomer], 3.35 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], A mixture of 3.35 g of docosan and 5.87 g of dilauroyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 75 ° C. at a temperature rise rate of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, based on the time when the internal temperature reached 60 ° C., 8.38 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was ionized at the time when 3 minutes passed and when 100 minutes passed. A solution dissolved in 25.16 g of exchange water was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes had elapsed with reference to the time when the internal temperature reached 60 ° C., it was 25.7%, so when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 25.7%.

Thereafter, the polymerization was completed in the same manner as in Example 5 to obtain fine methacrylic resin particles. The results are shown in Table 2.

Example 7
Place 1010 g of ion-exchanged water in the polymerization vessel (2) at room temperature [about 20 ° C.], then 0.367 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.19 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 317.7 g of methyl methacrylate, 83.8 g of styrene, 4.2 g of methyl acrylate [monofunctional monomer], 3.35 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator], A mixture of 4.19 g of docosan and 5.87 g of dilauroyl peroxide [polymerization initiator] was added, and bubbling was performed with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 75 ° C. at a temperature rise rate of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.3 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.15 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. Solution was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 23.2%, so when the rotational speed of the stirring blade (1) was reduced The polymerization rate in is less than 23.2%.

Thereafter, the polymerization was completed in the same manner as in Example 5 to obtain fine methacrylic resin particles. The results are shown in Table 2.

Comparative Example 6
In a polymerization vessel (2), 1009 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.366 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.19 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Furthermore, 321.6 g of methyl methacrylate, 83.7 g of styrene, 4.2 g of methyl acrylate [monofunctional monomer], 3.35 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator] and A mixture in which 5.86 g of dilauroyl peroxide [polymerization initiator] was mixed was added and bubbled with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 75 ° C. at a temperature rise rate of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.37 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was ionized when 3 minutes passed and when 100 minutes passed, based on the time when the internal temperature reached 60 ° C. A solution dissolved in 25.13 g of exchange water was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes passed with respect to the time when the internal temperature reached 60 ° C., it was 23.6%, and therefore when the rotational speed of the stirring blade (1) was reduced. The polymerization rate in is less than 23.6%.

Thereafter, the polymerization was completed in the same manner as in Example 5 to obtain fine methacrylic resin particles. The results are shown in Table 2.

Comparative Example 7
In a polymerization vessel (2), 1009 g of ion-exchanged water is added at room temperature [about 20 ° C.], then 0.366 g of sodium polymethacrylate [suspension stabilizer], polyoxyethylene polyoxypropylene ether [suspension stabilizer, Asahi Denka 4.19 g of “Pluronic F68” manufactured by Kogyo Co., Ltd.] and 0.084 g of hydroxypolypropylcellulose [suspension stabilizer] were added and dissolved. Further, 321.7 g of methyl methacrylate, 83.7 g of styrene, 4.2 g of methyl acrylate [monofunctional monomer], 3.35 g of ethylene glycol dimethacrylate [polyfunctional monomer], 0.063 g of terpinolene [polymerization regulator] and A mixture in which 5.86 g of dilauroyl peroxide [polymerization initiator] was mixed was added and bubbled with nitrogen gas. Thereafter, under the flow of nitrogen gas (5), the stirring blade (1) was rotated at an initial rotational speed (n ₀ ) of 750 rpm (12.5 sec ⁻¹ ) and stirred for 30 minutes. The stirring power (P ₀ ) at this time is 0.293 kW / m ³ . At this time, the tip speed (V ₀ ) of the stirring blade (1) is 2.36 m / sec. Further, the total amount (100% by mass) of the polymerization initiator is dilauroyl peroxide, and the proportion (LPO ratio) of dilauroyl peroxide in the polymerization initiator is 100% by mass.

Thereafter, the polymerization was carried out by raising the temperature from room temperature to the polymerization temperature of 75 ° C. at a temperature rise rate of about 2 ° C./minute while rotating the stirring blade (1) at the same rotation speed (n ₀ ) under nitrogen gas flow. At this time, 8.3 g of polyoxyethylene polyoxypropylene ether (suspension stabilizer) was dissolved in 25.15 g of ion-exchanged water when 3 minutes had passed, based on the time when the internal temperature reached 60 ° C. Solution was added. In addition, when 18 minutes passed from the time when the internal temperature reached 60 ° C. as a reference, the rotation of the stirring blade (1) was decelerated to set the rotation speed (n) to 340 rpm (5.67 sec ⁻¹ ). The stirring power (P) at this time is 0.0273 kW / m ³ and the tip speed (V) is 1.07 m / sec. Furthermore, when the polymerization rate was measured when about 40 minutes had elapsed with respect to the time when the internal temperature reached 60 ° C., it was 20.1%, and therefore when the rotational speed of the stirring blade (1) was reduced. The polymerization rate in is less than 20.1%.

Thereafter, the polymerization was completed in the same manner as in Example 5 to obtain fine methacrylic resin particles. The results are shown in Table 2.

Table 2
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
LPO ratio Docosan Power ratio (P / P ₀ ) Polymerization rate Aggregation D50
(Mass%) (parts by mass ^{* 1} ) (-) (%) presence / absence (μm)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Example 5 100 1.5 0.093 <24.9 None 17.2
Example 6 100 0.8 0.093 <25.7 None 14.1
Example 7 100 1.0 0.093 <23.2 None 16.2
Comparative Example 6 100 0 0.093 <23.6 Yes 15.6
Comparative Example 7 100 0 0.093 <20.1 Yes-
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
* 1: The use amount of docosane is shown by the use amount (mass part) per 100 parts by mass of the monomer.

It is a longitudinal cross-sectional view of an example of the superposition | polymerization apparatus used for manufacture of the methacryl resin particle by the manufacturing method of this invention. It is a cross-sectional view in the A-A 'cross section of FIG. It is a schematic diagram which shows the attachment angle of the stirring blade with respect to the stirring shaft.

Explanation of symbols

1: Stirring blade 11: Stirring shaft d: Diameter of stirring blade θ: Mounting angle 2: Polymerization vessel 2a: Inner surface 2b: Bottom surface D: Inner diameter 3: Polymerization mixture 4: Baffle 5: Nitrogen gas

Claims (5)

This is a method for producing fine methacrylic resin particles by initiating polymerization with a polymerization initiator while suspending the monomer mainly composed of methyl methacrylate together with the aqueous medium and suspending the monomer in the aqueous medium. ,
Formula (I)
C _m H _{2m + 2} (I)
[In formula, m shows the integer of 12-26. ]
Polymerizing the monomer in the presence of a linear saturated hydrocarbon represented by
A process for producing fine methacrylic resin particles, characterized in that, during the polymerization, the stirring power (P) is within a range of 1/3 or less of the initial stirring power (P ₀ ) when the polymerization is started. 75% by weight or more of the polymerization initiator is of the formula (II)

[In formula, p and q show the integer of 6-12 each independently. ]
The manufacturing method of Claim 1 which is a compound shown by these. The production method according to claim 1 or 2, wherein the amount of the linear saturated hydrocarbon represented by the formula (I) is 0.1 to 10 parts by mass per 100 parts by mass of the monomer. The production method according to any one of claims 1 to 3, wherein an amount of the polymerization initiator used is 0.01 to 5 parts by mass per 100 parts by mass of the monomer. The production method according to any one of claims 1 to 4, wherein the stirring power (P) is within the above range while the polymerization rate of the monomer is 25% or less.

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