JP4817358B2 - Method for producing vinyl resin fine particles - Google Patents

Description

  The present invention relates to a method for producing vinyl resin fine particles. Specifically, the present invention relates to a method for producing resin fine particles having an average particle size of about several μm to several tens of μm and a narrow particle size distribution.

Conventionally, a suspension polymerization method is known as a method for producing vinyl resin fine particles having an average particle diameter of several tens of μm to several hundreds of μm. In recent years, resin fine particles having a smaller particle size of about several μm to several tens of μm and a narrow particle size distribution have been used as light diffusing agents, toners, spacers, etc., and the resin particle size is small and the particle size distribution is narrow. There is a demand for resin fine particles.
However, in order to obtain resin fine particles by a conventional suspension polymerization method that has been conventionally performed, it is necessary to perform polymerization by setting the weight ratio (O / W) of the vinyl monomer to the aqueous medium to about 0.1. In addition to being inferior in productivity and economically disadvantageous, there are drawbacks such as it is difficult to produce resin fine particles having an average particle size of several μm to several tens of μm and a narrow particle size distribution. .

On the other hand, in order to produce resin fine particles having an average particle size of about several μm to several tens of μm and a narrow particle size distribution by suspension polymerization, a primary mixed solution is prepared by a high-speed rotary stirring device, and the primary mixing is performed. Techniques such as a method in which a liquid is further ejected from a nozzle under pressure to prepare and polymerize a secondary mixture (Patent Document 1), and a method in which a suspension is applied to an ultrasonic grinder (Patent Document 2). Has been reported.
However, in the production methods described in Patent Documents 1 and 2, resin fine particles having a relatively narrow particle size distribution can be obtained. However, the production process is complicated and the weight ratio of the vinyl monomer to the aqueous medium ( Under the condition of increasing (O / W), there is a problem that it is difficult to obtain resin fine particles having a narrow particle size distribution.

JP-A-4-156555 JP 7-188310 A

  The present invention solves the above-mentioned conventional problems, does not require a complicated manufacturing process, and has a narrow particle size distribution width even when the weight ratio (O / W) of the vinyl monomer to the aqueous medium is large. It aims at providing the manufacturing method of the vinyl resin fine particle which can manufacture resin fine particle efficiently.

That is, the present invention comprises an emulsifier and a screen with slits of the aqueous suspension liquid, which is arranged outside the stirrer and the stirrer rotating at high speed comprising (1) a vinyl monomer The mixture is supplied to a cylindrical container, and stirred at a tip peripheral speed of at least 5 m / sec to produce a mixed liquid in which vinyl monomer droplets are finely dispersed. The present invention relates to a method for producing fine vinyl resin particles, characterized in that vinyl monomer droplets are polymerized while stirring at a tip peripheral speed of a stirring blade of a polymerization reaction tank in a range of 0.5 to 2 m / sec. Preferably, (2) the inside of the cylindrical container equipped with the emulsifying device is in a liquid-sealed state, and the vinyl monomer droplets are continuously finely dispersed. (3) The said emulsification apparatus is provided. The inside of the cylindrical container is kept at at least 0.005 MPa, and the vinyl monomer droplets according to the above (1) or (2) are continuously dispersed finely. (4) The above-described (1) to (1), wherein the inside of the cylindrical container equipped with the emulsifying device is kept at 5 ° C. to 40 ° C. and the vinyl monomer droplets are finely dispersed. the method of any manufacturing vinyl resin fine particles according to the 3), and the gist.

  By preparing the emulsion using the emulsifier of the present invention, the emulsion does not cause cavitation (a phenomenon in which dissolved gas or the like is bubbled when the pressure is locally reduced), and vinyl. Resin mixture having a small particle size distribution even under conditions where the weight ratio (O / W) of the vinyl monomer to the aqueous medium is large. Can be manufactured efficiently.

In the method of the present invention, the “aqueous suspension containing a vinyl resin” is, as described later, an aqueous medium (usually deionized water), a vinyl monomer, a suspending agent, a polymerization initiator, a surfactant. This is a suspension in which an agent or the like is mixed, and this is hereinafter referred to as an “aqueous suspension”.
The method of the present invention by means of an emulsifying machine and a screen having a plurality of slits arranged outside the stirrer and the stirrer rotating at high speed as shown in FIG. 1, the agitator tip peripheral speed 5 m / Stir the aqueous suspension at a sec. or more, and polymerize the resulting mixture (emulsion) while stirring the tip peripheral speed of the stirring blade of the reaction vessel in the range of 0.5-2 m / sec in the polymerization reactor. a method for producing a vinyl resin fine particles by causing the. In the following, both the aqueous suspension that has not been agitated in the cylindrical container and the mixture of the mixed liquid and the aqueous suspension that have been agitated in the cylindrical container are mixed after the agitation has been completed. The liquid is also referred to as “mixed liquid” for convenience.
By the above production method, resin fine particles having a narrow particle size distribution can be efficiently produced even under a condition where the weight ratio (O / W) of the vinyl monomer to the aqueous medium is large.

The production method of the present invention will be described in more detail.
One of the features of the present invention is to use a specific emulsifying apparatus having a structure as shown in FIG.
FIG. 1 shows a conceptual diagram of an emulsifying device 6 used in the method of the present invention. As shown in FIG. 1, the emulsifying device 6 in the present invention covers the outside of the stirrer 2 with a slight interval so as not to hinder the rotation of the stirrer 2 and the stirrer 2 rotated at high speed by the motor M. It has a screen 3 with a plurality of slits arranged. The stirrer 2 of the emulsifying device 6 is disposed in the cylindrical container 1. In FIG. 1, reference numeral 4 indicates a liquid (mixed liquid) suction port, and reference numeral 5 indicates a liquid (mixed liquid) discharge port (slit). An arrow 7 indicates the flow of the liquid (mixed liquid). The liquid mixture is introduced from the liquid suction port 4 and discharged from the liquid discharge port 5 (slit). In addition, in FIG. 1, the screen 3 shows the state which cut in part so that the rotating shaft of the stirrer 2 and the stirrer 2 can be seen.
FIG. 2 is a view for explaining the flow of the mixed liquid by the rotation of the stirrer 2 and the stirrer 2. FIG. 2 (1) shows a side view of the agitator 2. Reference numeral 21 denotes a blade of a stirrer. 2 (2) is a diagram for explaining the flow of the mixed liquid when the agitator 2 shown in FIG. 2 (1) is rotated, where a is an axial flow, b is a centrifugal flow, c Indicates the flow in the discharge direction, respectively. FIG. 2 (3) shows a side view of a stirrer according to another embodiment having a blade shape different from that of FIG. 2 (1). FIG. 3 shows a side external view of the screen 3 arranged outside the stirrer. The screen 3 is provided with a plurality of slits 5 having a small gap (slit width: d3).
In FIG. 1, h1 is the height of the liquid surface, d1 is the outer diameter of the stirrer, and d2 is the inner diameter of the cylindrical container.

  When the mixed liquid containing the vinyl monomer is stirred at the tip speed of the stirrer 5 of 5 m / sec or more by the emulsifying device having the above structure, the mixed liquid is rotated from the suction port 4 of the stirrer blade 21 The mixed liquid is taken in above and forms a discharge direction flow c as shown in FIG. 2 (2), and the flow of the mixed liquid whose speed is increased when passing through the slit 5 of the screen 3 shown in FIG. It becomes a flow and is continuously discharged into the mixed liquid in the tank through the slit 5. At this time, a liquid mixture in which droplets of the vinyl monomer are refined by a shearing force between the liquid mixtures at a speed interface generated due to irregular fluctuations in the speed is obtained.

In a conventional emulsifying apparatus composed of a stirrer 101 that rotates at a high speed as shown in FIG. 5 and a stationary ring (stator) 102 arranged to surround the stirrer 101, the mixed liquid is rotated by the stirrer 101. Accordingly, the vinyl-based monomer is sucked from the liquid suction port 103 and discharged from the discharge port 104 by the shearing force between the mixed liquid and the contact wall surface of the stationary ring 102 arranged around the stirrer 101. A liquid mixture with a refined body is obtained. In FIG. 5, reference numeral 100 indicates a cylindrical container, and reference numeral 105 indicates a commutation plate.
The emulsification apparatus having the structure shown in FIG. 1 of the present invention may cause cavitation (a phenomenon in which dissolved gas is bubbled when the pressure is locally reduced) as compared with the conventional apparatus shown in FIG. In addition, it is possible to prepare a liquid mixture in which the vinyl monomer droplets have good stability, and the particles even under the condition that the weight ratio (O / W) of the vinyl monomer to the aqueous medium is large. Resin fine particles having a narrow diameter distribution can be efficiently produced.

In the emulsifying apparatus having the above structure in the present invention, when the tip peripheral speed of the stirrer 2 is less than 5 m / sec, the vinyl monomer droplets cannot be sufficiently miniaturized and obtained by a polymerization reaction. There is a possibility that not only the average particle size of the polymer to be obtained becomes large but also the particle size distribution becomes wide. In addition, although there is no particular upper limit on the tip peripheral speed of the stirrer 2, the effect of refining the vinyl monomer droplets is almost unchanged under conditions exceeding 35 m / sec. It is preferable to stir in the range of 5 to 35 m / sec. More preferably, it is 7-32 m / sec. Here, the tip peripheral speed of the stirrer 2 means the rotational speed of the end of the blade of the stirrer farthest from the rotating shaft of the stirrer 2. The stirrer 2 that rotates at a high speed generates a flow in the discharge direction (the flow of the mixed liquid at an increased speed; the jet flow) determined by the magnitude of the flow component in the axial direction and the magnitude of the flow component in the centrifugal direction depending on the lead angle. Set to face the slit of the screen, and by appropriately determining the absolute velocity of jet flow and the number of intermittents depending on the slit width and the number of slits, the desired fineness is controlled and the average particle size and particle size distribution width are controlled. be able to.
The slit width of the screen is usually 0.5 to 5 mm, preferably 1 to 3 mm. Moreover, the length of a slit is 5-50 mm normally, and 10-30 mm is preferable. Moreover, the number of slits is 5-50 normally, and 10-25 are preferable.

  Further, the cylindrical container used for finely dispersing the vinyl monomer droplets in the mixed solution has a ratio (d2 / d1) of the outer diameter (d1) of the stirrer to the inner diameter (d2) of the container. It is preferable that it is 2-10. Furthermore, it is preferable that the value of d2 / d1 is 3-7. Within this range, the vinyl monomer droplets can be efficiently and finely dispersed.

  Moreover, it is preferable to supply so that ratio (h1 / d1) of the outer diameter (d1) of a stirrer and the liquid level height (h1) of a liquid mixture may be 2-10. Furthermore, the value of h1 / d1 is preferably 3 to 5.

  Further, as the agitator, various types of agitators such as a turbine type, an all type, a gate type, and a propeller type can be used.

  A typical embodiment of the suspension polymerization of the present invention is, for example, a suspension containing a polymerization initiator and a vinyl monomer after dispersing a surfactant in an aqueous medium in which a suspension is dispersed. Is mixed in a cylindrical container equipped with the emulsifying device, and high-speed stirring is performed under the above conditions to prepare a mixed solution in which vinyl monomer droplets are finely dispersed. Thereafter, the prepared mixed liquid is introduced into a polymerization reactor, oxygen is removed from the reaction system, and then suspension polymerization is performed by heating the emulsion while stirring at a predetermined temperature for a predetermined time. . The above suspension may be directly prepared in an emulsifying device, prepared in advance in a separate mixing tank, introduced into the emulsifying device, and circulated to make fine vinyl monomer droplets. You can also.

  Examples of the vinyl monomer used in the method for producing resin fine particles of the present invention include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, pn-hexylstyrene, p-octylstyrene , Vinyl aromatic compounds such as styrene sulfonic acid and sodium styrene sulfonate; acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate has 1 to 10 carbon atoms Alkyl esters, etc .; methyl methacrylate, methacrylate Include acrylonitrile, methacrylonitrile group-containing unsaturated compounds such as nitrites and the like; Le, propyl methacrylate, butyl methacrylate, alkyl esters having a carbon number of 1 to 10 methacrylic acid such as 2-ethylhexyl methacrylate and the like.

  Examples of the polymerization initiator used in the method for producing resin fine particles of the present invention include azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, dicumyl peroxide, and t-butylperoxy-2. Examples include initiators soluble in monomers such as ethyl hexanoate, t-butyl peroxybenzoate, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, lauroyl peroxide. Usually, the amount of the polymerization initiator is preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the total weight of the charged monomers.

In the method for producing resin fine particles of the present invention, an alkyl mercaptan such as dodecyl mercaptan or a chain transfer agent such as α-methylstyrene dimer is added to the polymerization reaction system as necessary in the production method of resin fine particles. Can do. The amount of the chain transfer agent used is usually about 0.01 to 3 parts by weight with respect to 100 parts by weight of the total weight of all monomers to be polymerized.

Moreover, the preparation amount of the vinyl-type monomer in the manufacturing method of the resin fine particle of this invention is the range of 5-100 weight part normally with respect to 100 weight part of aqueous media. Moreover, in order to provide solvent resistance to the resin fine particles of the present invention, a vinyl monomer having two or more vinyl groups in the molecule can be used as a crosslinking agent. For example, (meth) acrylic monomers such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, divinylbenzene, divinylnaphthalene, etc. And aromatic divinyl compounds. These crosslinking agents may be used alone or in combination of two or more, and the amount used is preferably about 0.5 to 20 parts by weight with respect to 100 parts by weight of the total weight of the charged monomers.

  Examples of the suspending agent used in the method for producing resin fine particles of the present invention include tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, ferric hydroxide, and hydroxide. Fine inorganic suspensions such as titanium, magnesium hydroxide, barium phosphate, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, talc, kaolin, bentonite, polyvinylpyrrolidone, polyvinyl alcohol, ethylcellulose, hydroxypropyl An organic suspending agent such as methylcellulose can be used. More preferred are tricalcium phosphate, hydroxyapatite, and magnesium pyrophosphate. These suspending agents may be used alone or in combination of two or more.

  The amount of the suspending agent used in the present invention is usually 100 parts by weight with respect to 100 parts by weight of the aqueous medium of the suspension polymerization system (referring to all water in the system including water such as the reaction product-containing slurry). The solid content is 0.05 to 20 parts by weight, preferably 0.3 to 15 parts by weight. If the amount is less than 0.05 parts by weight, the vinyl monomer cannot be suspended and stabilized, and a resin mass may be generated. If the amount exceeds 20 parts by weight, it is not preferable from the viewpoint of production cost. In addition, the particle size distribution may be widened.

Examples of the surfactant used in the method for producing resin fine particles of the present invention include sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium lauryl sulfate, sodium α-olefin sulfonate, and sodium dodecylphenyl oxide disulfonate. Anionic surfactants; Nonionic surfactants such as polyoxyethylene dodecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether; alkylamine salts such as coconut amine acetate and stearylamine cetate and lauryltrimethylammonium Cationic surfactants such as quaternary ammonium such as chloride and stearyltrimethylammonium chloride; lauryl betaine and stearyl betaine Which alkyl betaines and amphoteric surfactants such as alkyl amine oxides such as lauryl dimethyl amine oxide.
An anionic surfactant is preferable. More preferably, it is an alkylsulfonic acid alkali metal salt (preferably sodium salt) having 8 to 20 carbon atoms. Thereby, the effect of the outstanding suspension stabilization is acquired.
The addition amount of the surfactant is preferably in the range of 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the vinyl monomer.

  If necessary, electrolytes such as inorganic salts such as lithium chloride, potassium chloride, sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, sodium nitrate, sodium carbonate, and sodium bicarbonate can be added.

In the production of vinyl resin fine particles by the method of the present invention, vinyl monomer droplets can be refined by either a batch method or a continuous method. It is desirable economically and efficiently to carry out it continuously industrially and then to continuously produce it for the polymerization reaction.
When performing continuously, for example, as shown in FIG. 4, a mixing tank 11 for preparing an aqueous suspension containing a vinyl monomer and an emulsifying device 10 are connected to a conduit 13 having a mixed liquid circulation pump P. the in connection with mixture through the circulation pump P is continuously introduced into the emulsification device 10, droplets of vinyl monomer in the suspension is finely divided by the emulsifying apparatus, a liquid represented by the arrow While circulating in a flow, a liquid mixture in which fine droplets of a predetermined vinyl monomer are dispersed is introduced into a polymerization reaction tank (not shown) by opening the liquid outlet valve V to perform a polymerization reaction. To obtain the desired resin fine particles. In FIG. 4, the code | symbol G is a pressure gauge for measuring the pressure in the container mentioned later.
When the vinyl monomer is continuously refined in this way, the inside of the cylindrical container 12 is liquid-sealed with a mixed solution (the filling rate in the container is 100%) and refined. This is preferable because air entrainment can be prevented during the conversion, and the vinyl monomer droplets can be made fine in a short time.

  Further, when the droplets of the vinyl monomer are refined by the above-described method, the inside of the cylindrical container 12 is maintained in a slightly pressurized state of 0.005 MPa or more, and the vinyl monomer droplets are maintained. It is preferable to refine the size. By holding the inside of the container in a pressurized state of 0.005 MPa or more, air entrainment can be further prevented, and the vinyl monomer droplets can be efficiently miniaturized in a short time, which is preferable. . When the inside of the container is less than 0.005 MPa, when the vinyl monomer droplets are refined in the container, air is easily entrained, and the vinyl monomer droplets are fined to a predetermined particle size. Since there is a possibility that the time required for conversion will increase, it is preferably 0.01 MPa or more, more preferably 0.02 MPa or more, and more preferably 0.05 MPa or more. However, if the pressure is too high, it is necessary to increase the pressure resistance of the cylindrical container, which may increase the cost of the apparatus. Therefore, the upper limit is preferably about 0.5 MPa. In addition, the pressure here means a gauge pressure, and is a value obtained by measuring the water pressure of the mixed solution with the pressure gauge G. Further, in order to increase the water pressure of the mixed liquid, the mixed liquid is simply circulated so that the mixed liquid pressure in the cylindrical container is increased.

When the vinyl monomer droplets are refined by the method of the present invention, the temperature in the container (mixed solution) is preferably 5 to 40 ° C. When the temperature in the container is less than 5 ° C., after the vinyl monomer droplets are refined to a predetermined particle size, the heating time for raising the temperature to the polymerization temperature in the subsequent polymerization reaction becomes longer. Therefore, it is not preferable from the viewpoint of manufacturing cost. When the temperature exceeds 40 ° C., it is difficult to make the vinyl monomer droplet finer to a predetermined particle size. Preferably, it is 10-30 degreeC.
The temperature in the container can be controlled by attaching a jacket to a container for refining droplets of vinyl monomer and circulating cooling water or hot water.

  The mixed solution prepared by the above method is then subjected to a suspension polymerization reaction. This suspension polymerization reaction is carried out in the same manner as conventional suspension polymerization. When carrying out the polymerization reaction, it is preferable to carry out the polymerization while maintaining the inside of the polymerization reaction tank in a pressurized state of 0.2 MPa or more. By carrying out the polymerization while maintaining the inside of the reaction vessel at 0.2 MPa or more, the generation of bubbles can be suppressed, and therefore, the bubbles generated during the polymerization stay and the formation of condensed beads can be suppressed, which is preferable. When the pressurized state is less than 0.2 MPa, bubbles generated during polymerization cannot be sufficiently suppressed, and there is a high possibility that condensed beads are generated. Preferably, it is 0.3 MPa or more, and more preferably 0.5 MPa or more. The pressurization is preferably performed by introducing nitrogen. However, if the pressure is too high, it is necessary to increase the pressure resistance of the reaction tank, which may increase the cost of the apparatus. Therefore, the upper limit is preferably about 5 MPa. In addition, the pressure here means a gauge pressure, and is a value obtained by measuring the gas phase part at the top of the reaction tank with a pressure gauge.

  The average particle diameter (d50) of the resin fine particles obtained in the present invention is about 1 to 100 μm and the dispersity (d90 / d10) is in the range of less than 10, and when the vinyl monomer droplets are finely dispersed. The average particle diameter of the resin fine particles can be controlled by changing the rotation speed of the agitator and the amount of the suspending agent.

  Here, the average particle diameter (d50) is obtained by dispersing resin fine particles in water and measuring the particle size distribution by a laser diffraction method (HELOS version 4.4.1 manufactured by SYMPATEC), and the cumulative volume with respect to the volume of all particles is 50%. The particle size when the particle size becomes 50% particle size (d50), and the dispersity (d90 / d10) is the particle size when the cumulative volume with respect to the volume of all particles is 10% and 90%, respectively. 10% particle diameter (d10), 90% particle diameter (d90), and 90% particle diameter divided by 10% particle diameter. The shape of the resin fine particles is not limited to a spherical shape, and may be a particle having an elliptical cross section, or a deformed particle having a slight unevenness on the surface.

In the polymerization reaction, polymerization is performed while stirring at a tip peripheral speed (rotational speed at the end of the stirring blade farthest from the rotating shaft of the stirrer) in the range of 0.5 to 2 m / sec . By polymerizing while stirring at a tip peripheral speed of 0.5 to 2 m / sec in the range of the stirring blade, it is possible to prevent the particles from being coalesced to increase the particle diameter of the polymer. Since generation | occurrence | production of the bubble used as a generation | occurrence | production cause can be suppressed, it is preferable.
When the tip peripheral speed of the stirring blade is less than 0.5 m / sec, the particles tend to coalesce, and the problem that the particle size of the polymer obtained by polymerization becomes larger is more than 2 m / sec. There is a possibility that bubbles are generated in the reactor and the resin fine particles floating in the staying bubbles become condensed beads.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

Example 1
A screen with a high-speed rotating stirrer (rotor “R2” manufactured by M Technique Co., Ltd., width 30.5 mm) and a fine gap slit (screen manufactured by M Technique Co., Ltd.) shown in FIG. “S1.5-24” is used, consisting of 21 slits with a slit width of 1.5 mm and a slit length of 12 mm, and three slits with a slit width of 1.5 mm and a slit length of 24 mm, and between the slits with a length of 24 mm A cylindrical container 1 (width 180 mm, height 210 mm) equipped with an emulsifying device as shown in FIG. 1 is formed of 1350 g of deionized water. After adding 22 g of sodium pyrophosphate and dissolving, 40 g of powdered magnesium chloride hexahydrate is added and stirred at room temperature for 30 minutes for suspension. Magnesium pyrophosphate slurry as prepared.

  Next, 6.8 g of a 10% aqueous solution of sodium alkylsulfonate, 150 g of styrene monomer in advance, and t-butylperoxy 2-ethylhexanoate as a polymerization initiator were added to the above prepared magnesium pyrophosphate-containing water slurry. 45 g and a solution in which 0.15 g of t-butylperoxy 2-ethylhexyl carbonate was dissolved were stirred at a high speed for 15 minutes at a tip peripheral speed of 8 m / sec (rotation speed: 5000 rpm) to form droplets of styrene monomer. Produced a finely dispersed mixture. In addition, the temperature of the liquid mixture was 30 degreeC. The motor power of the stirrer was 0.8 KW.

  Next, the mixed solution was put into a polymerization reaction tank having a capacity of 3000 ml, the inside of the reaction tank was purged with nitrogen gas, and then rotated at a tip peripheral speed of 0.63 m / sec (rotation speed: 200 rpm) of the stirring blade of the reaction tank. While stirring, the temperature was raised to 90 ° C. over 1 hour and a half, and further raised to 120 ° C. over 5 hours. During this time, nitrogen gas was injected after 4 hours from the arrival at 90 ° C., and the inside of the reaction tank was pressurized to 0.5 MPa. Thereafter, the temperature was further maintained at 120 ° C. for 8 hours. Subsequently, it took 4 hours to cool to 30 ° C. to obtain a polymerization product.

Next, 100 ml of nitric acid (5%) was added to the polymer obtained by filtering the polymerization product and stirred to dissolve the deposit, filtered, washed with water, and dried to obtain a spherical styrene resin. The obtained resin particles were measured by a laser diffraction type particle size distribution measuring apparatus. The volume average particle diameter (d50) was 4.4 μm and the dispersity (d90 / d10) was 4.9.
The average particle diameter (d50) and dispersity (d90 / d10) were measured by the method described above. In addition, since the obtained resin particle was spherical, the shape factor of the particle | grains of the measuring apparatus in the case of a measurement was set to 1 (spherical shape).
Ratio (d90 / d10) (dispersion degree) of 90% particle diameter to 10% particle diameter of resin fine particles is evaluated as “「 ”when less than 5,“ ◯ ”when 5 or more but less than 10 is evaluated as“ × ”. did. The same evaluation was made hereinafter.

Example 2
In a cylindrical container (width 180 mm, height 210 mm) equipped with the same emulsifying apparatus as used in Example 1, 900 g of deionized water was added, and 14.7 g of sodium pyrophosphate was added and dissolved, and then powdered. 26.7 g of magnesium chloride hexahydrate was added and stirred at room temperature for 30 minutes to prepare a magnesium pyrophosphate slurry as a suspending agent.

Then, to the prepared magnesium pyrophosphate-containing water slurry, 4.5 g of a 10% aqueous solution of sodium alkylsulfonate, 600 g of styrene monomer in advance, 1.8 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator, and The solution in which 0.6 g of t-butylperoxy 2-ethylhexyl carbonate was dissolved was stirred at high speed for 15 minutes at a tip peripheral speed of 16 m / sec (rotation speed: 1000 rpm), and styrene monomer droplets were finely dispersed. A mixture was produced. The mixture was polymerized in the same manner as in Example 1 to obtain a polymerized biological product. The obtained polymerization product was treated in the same manner as in Example 1 to obtain resin fine particles having an average particle size (d50) of 9.6 μm and a dispersity (d90 / d10) of 4.8.

Example 3
The present example shows a method in which a vinyl monomer-containing aqueous suspension is refined by the continuous refinement process shown in FIG. 4 and used for polymerization. First, 900 g of deionized water is put into a cylindrical mixing tank 11 (width 180 mm, height 210 mm), and further 14.7 g of sodium pyrophosphate is added and dissolved, and then powdered magnesium chloride hexahydrate is added. 26.7 g was added and stirred at room temperature for 30 minutes to prepare a magnesium pyrophosphate slurry as a suspending agent.

Subsequently, to the prepared magnesium pyrophosphate-containing water slurry, 4.5 g of a 10% aqueous solution of sodium alkylsulfonate, 600 g of styrene monomer in advance, 1.8 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator, and t -A solution in which 0.6 g of butyl peroxy 2-ethylhexyl carbonate was dissolved was added to prepare a mixed solution.
A screen with a high-speed agitator (rotor “R2” manufactured by M Technique Co., Ltd., width 30.5 mm) and a minute gap slit (screen manufactured by M Technique Co., Ltd.) shown in FIG. “S1.5-24” is used, consisting of 21 slits with a slit width of 1.5 mm and a slit length of 12 mm, and three slits with a slit width of 1.5 mm and a slit length of 24 mm, and between the slits with a length of 24 mm 4) A 350 cc cylindrical container 12 (width 72 mm, height 100 mm) provided with the emulsifying device 10 shown in FIG. Continuously supplied, circulating the cooling water and maintaining the temperature in the container at 20 ° C. for 20 minutes at the tip peripheral speed of 16 m / sec (rotation speed 10000 rpm) of the stirrer, Stir at high speed to produce a mixture.

  Next, the liquid mixture produced was opened, the liquid outlet valve V was opened, the polymerization mixture was introduced into a polymerization reaction tank (not shown), and the mixture was polymerized while being stirred at a tip blade peripheral speed of 1.26 m / sec (rotation speed: 400 rpm). . After completion of the polymerization reaction, resin fine particles were obtained in the same manner as in Example 1. The obtained resin particles had an average particle diameter (d50) of 3.9 μm and a dispersity (d90 / d10) of 3.9.

Example 4
It refined | miniaturized by the continuous method like Example 3. FIG. In the same manner as in Example 3, a magnesium pyrophosphate slurry as a suspension was prepared.
Next, 4.5 g of sodium alkylsulfonate 10% aqueous solution, 240 g of methyl methacrylate in advance, and 360 g of styrene monomer were added to the prepared magnesium pyrophosphate-containing water slurry, and t-butylperoxy 2-ethylhexanoate as a polymerization initiator was added. A solution in which 1.8 g of ate and 0.6 g of t-butylperoxy 2-ethylhexyl carbonate were dissolved was added to prepare a mixed solution.
The mixed solution is continuously supplied to the same emulsifying apparatus as in Example 3 at a rate of 1 L / min with a circulation pump, the degree of opening of the liquid outlet valve is adjusted so that the pressure in the container is 0.03 MPa, and the cooling water is supplied. While circulating, the temperature inside the container was maintained at 10 ° C., and the mixture was prepared by stirring at high speed for 10 minutes at a rotor tip peripheral speed of 24 m / sec (rotation speed: 15000 rpm).

  Next, the produced liquid mixture was opened to the liquid outlet valve V, led to the polymerization reaction tank, and polymerized while being stirred while rotating at a tip peripheral speed of 0.95 m / sec (rotation speed: 300 rpm). After completion of the polymerization reaction, resin fine particles were obtained in the same manner as in Example 1. The obtained resin particles had an average particle diameter (d50) of 3.5 μm and a dispersity (d90 / d10) of 3.4.

Example 5
It refined | miniaturized by the continuous method like Example 3. FIG. In the same manner as in Example 3, a magnesium pyrophosphate slurry as a suspension was prepared.
Next, to this water slurry containing magnesium pyrophosphate slurry, 4.5 g of a 10% aqueous solution of sodium alkyl sulfonate, 600 g of methyl methacrylate in advance, 1.8 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator, and A solution in which 0.6 g of t-butylperoxy 2-ethylhexyl carbonate was dissolved was continuously supplied to the same emulsifying apparatus as in Example 3 at a rate of 1 L / min with the circulation pump P, and the valve opening degree at the liquid outlet To adjust the pressure in the container to 0.06 MPa, circulate cooling water and maintain the temperature in the container at 20 ° C., while maintaining the tip peripheral speed of 32 m / sec (rotation speed 20000 rpm) for 5 minutes. Then, the mixture was stirred at a high speed to prepare a mixed liquid in which the monomers were finely dispersed.

Subsequently , the produced mixed liquid was introduced into a polymerization reaction tank , and the polymerization was performed while stirring at a tip peripheral speed of the reaction tank at a tip peripheral speed of 0.63 m / sec (rotation number: 200 rpm). Thus, resin fine particles were obtained. The obtained resin particles had an average particle size (d50) of 3.0 μm and a dispersity (d90 / d10) of 2.9.

Comparative Example 4
In the same manner as in Example 3, 1000 g of deionized water was placed in a cylindrical mixing vessel 11 (width 180 mm, height 210 mm), and further 16.2 g of sodium pyrophosphate was added and dissolved. 29.6 g of hexahydrate was added and stirred at room temperature for 30 minutes to prepare a magnesium pyrophosphate slurry as a suspending agent.

Next, to this water slurry containing magnesium pyrophosphate slurry, 5.0 g of a 10% aqueous solution of sodium alkylsulfonate, 500 g of styrene monomer in advance, 1.5 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator and t -A solution in which 0.5 g of butyl peroxy 2-ethylhexyl carbonate was dissolved was continuously supplied to the same emulsifying apparatus as used in Example 3 at a rate of 1 L / min with the circulation pump P, and the valve at the liquid outlet While maintaining the pressure in the container at 0.01 MPa by adjusting the degree of opening, the mixture was manufactured by stirring at high speed for 15 minutes at a rotor tip peripheral speed of 32 m / sec (rotation speed 20000 rpm). The temperature of the mixed solution was 50 ° C.
Subsequently, the produced mixed liquid is introduced into a polymerization reaction tank, and the polymerization is performed while stirring and rotating at a tip peripheral speed of 2.2 m / sec (rotation number: 700 rpm) of the stirring blade of the reaction tank. Thus, resin fine particles were obtained. The obtained resin particles had an average particle diameter (d50) of 16.2 μm and a dispersity (d90 / d10) of 9.2.

Comparative Example 1
Using a conventional emulsifying device composed of a stirrer 101 (width 30.5 mm) rotating at a high speed and a stationary ring (stator) 102 arranged so as to surround it as shown in FIG. Resin fine particles were obtained in the same manner as in Example 1 except that the mixed solution produced by high-speed stirring at 8 m / sec (rotation speed 5000 rpm) for 15 minutes was polymerized. The obtained resin particles had an average particle diameter (d50) of 11.9 μm and a dispersity (d90 / d10) of 14.0.

Comparative Example 2
Resin fine particles were polymerized in the same manner as in Example 2 except for polymerizing the mixed solution produced by high-speed stirring for 15 minutes at the tip peripheral speed of 16 m / sec (rotation speed: 10000 rpm) with the same emulsifier as in Comparative Example 1. Obtained. The obtained resin particles had an average particle size (d50) of 53.9 μm and a dispersity (d90 / d10) of 12.5.

Comparative Example 3
The same emulsification apparatus as used in Example 1 was used, and the mixed liquid produced by high-speed stirring for 15 minutes at a tip peripheral speed of 4 m / sec (rotation speed 2500 rpm) was polymerized in the same manner as in Example 1. Thus, resin fine particles were obtained. The obtained resin particles had an average particle diameter (d50) of 34.5 μm and a dispersity (d90 / d10) of 13.8.

Tables 1 and 2 show the 50% particle diameter (d50) of resin fine particles and the ratio of 90% particle diameter to 10% particle diameter (d90 / d10) in each of the above Examples and Comparative Examples. In addition, O / W in Table 1 and Table 2 means the weight ratio of the monomer with respect to water.
From Tables 1 and 2, the resin fine particles of the present invention can efficiently produce resin fine particles with a narrow particle size distribution even under conditions where the weight ratio (O / W) of the vinyl monomer to the aqueous medium is large. I understand.

The schematic diagram which shows an example of the emulsification apparatus of this invention. The agitator of the emulsifying device of the present invention is shown, (1) shows a side view of the agitator, and (2) shows the flow of liquid by the agitator. (3) shows a side view of another embodiment of a stirrer having a different blade shape. An example of the screen of the emulsification apparatus of this invention is shown. An example of the continuous refinement | miniaturization process in this invention is shown. The emulsification apparatus provided with the conventional stirrer and stationary ring is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical container 2 Stirrer 21 Wing | blade 3 Screen 4 Liquid inlet 5 Slit 6, 10 Emulsifier 7 Liquid flow 11 Mixing tank 12 Cylindrical container 13 Conduit 100 Cylindrical container 101 Stirrer (turbine)
102 Fixed ring (stator)
103 Liquid suction port 104 Liquid discharge port 105 Commutation plate 106 Liquid flow M Motor d1 Stirrer width d2 Container width d3 Slit width h1 Liquid surface height a Axial flow b Centrifugal flow c Discharge flow path

Claims (4)

An aqueous suspension containing a vinyl monomer is supplied to a cylindrical container equipped with an emulsifying device composed of a stirrer rotating at high speed and a screen having a slit disposed outside the stirrer. Is stirred at a tip peripheral speed of at least 5 m / sec to produce a mixed liquid in which vinyl monomer droplets are finely dispersed, and then the vinyl monomer droplets in the mixed liquid are A method for producing vinyl resin fine particles, wherein polymerization is performed while stirring at a tip peripheral speed of a stirring blade of a polymerization reaction tank in a range of 0.5 to 2 m / sec .   2. The production of vinyl resin fine particles according to claim 1, wherein the inside of the cylindrical container provided with the emulsifying device is liquid-sealed to continuously disperse the vinyl monomer droplets finely. Method.   The vinyl system according to claim 1 or 2, wherein the inside of the cylindrical container provided with the emulsifying device is maintained at least at 0.005 MPa, and droplets of the vinyl monomer are continuously finely dispersed. Production method of resin fine particles.   The inside of the cylindrical container provided with the said emulsification apparatus is hold | maintained at 5 to 40 degreeC, and the droplet of a vinyl-type monomer is disperse | distributed finely, The vinyl in any one of Claims 1-3 characterized by the above-mentioned. For producing resin-based resin fine particles.

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