JP2012177043A - Method of manufacturing acrylic polymer particle, and method of adjusting mechanical characteristics level for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a mechanical characteristics level of an acrylic polymer particle without changing a content of compounding formulation of a monomer compound, when the acrylic polymer particle is manufactured by radical polymerization of the acrylic monomer by discharging a monomer composition including an acrylic monomer and a polymerization initiator from a micro channel to a continuous phase, to form droplets of the monomer composition in the continuous phase, and after that, by radical polymerization of the acrylic monomer by heating the droplets.SOLUTION: The droplets of the monomer composition is heated by microwave irradiation. At that time, a heating temperature T of the droplets is set between a decomposition temperature T1 of the radical polymer initiator, and a heating temperature T2 at which prescribed mechanical characteristics of the acrylic polymer particle is obtained.

Description

  The present invention relates to a method for producing acrylic polymer particles using a microchannel.

  A method using a microchannel is known as a method for producing fine solid particles having good monodispersity. In this method, a dispersion phase composition (monomer composition) containing a reactive monomer and a thermal polymerization initiator is dispersed in a continuous phase via a microchannel to prepare an emulsion, and the emulsion is heated. This is a method for obtaining a suspension in which solid fine particles (polymer particles) obtained by radical polymerization of a reactive monomer are suspended in a continuous phase (Patent Document 1).

Japanese Patent No. 3616909

  By the way, there are cases where various levels of compressive strength are required for the mechanical properties of polymer particles to be obtained using microchannels, for example, compressive strength, depending on the purpose and mode of use of the polymer particles.

  In order to respond to such a request with the technique of Patent Document 1, it is conceivable to change the heating temperature at the time of polymerization, but the heating temperature is set by general heating block heating as in the case of emulsion preparation. Even if it was changed, the level of compressive strength could not be changed greatly. This is considered to be because once the polymerization starts, the polymerization proceeds at a stretch, and the dependence of the compressive strength on the polymerization temperature is very low. For this reason, it has been necessary to respond by changing the type and blending ratio of the constituent components of the monomer composition, but changing the content of the blending formulation of the monomer composition will change the level of the desired mechanical properties. There is a problem that it may cause unintentional changes in other mechanical properties.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and a monomer composition containing an acrylic monomer and a polymerization initiator is discharged from a microchannel to a continuous phase, thereby forming a continuous phase. When the acrylic polymer particles are produced by forming droplets of the monomer composition therein and then radically polymerizing the acrylic monomer by heating the droplets, the content of the formulation of the monomer composition is changed. Without being able to adjust the level of mechanical properties of the acrylic polymer particles.

  The inventors of the present invention have proposed that when the droplets of the monomer composition existing in the continuous phase are heated by microwave irradiation to radically polymerize the acrylic monomer, the mechanical temperature of the acrylic polymer particles is controlled by controlling the heating temperature. It has been found that the characteristic level can be adjusted, and the present invention has been completed.

That is, the present invention discharges a monomer composition containing an acrylic monomer and a radical polymerization initiator from a microchannel to a continuous phase, thereby forming droplets of the monomer composition in the continuous phase, and then A method for producing acrylic polymer particles by heating the droplets to radically polymerize the acrylic monomer,
The droplet is heated by microwave irradiation, and the heating temperature T of the droplet at that time is the heating temperature at which the decomposition temperature T1 of the radical polymerization initiator and the desired mechanical properties of the acrylic polymer particles are obtained. Provided is a production method characterized by adjusting the mechanical property level of acrylic polymer particles by setting between T2 and T2.

Further, this production method of the present invention has significance as a method for adjusting the mechanical properties of acrylic polymer particles, and the invention of this adjustment method is also an embodiment of the present invention. That is, the present invention discharges a monomer composition containing an acrylic monomer and a radical polymerization initiator from a microchannel to a continuous phase, thereby forming droplets of the monomer composition in the continuous phase, and then A method for adjusting mechanical properties of acrylic polymer particles obtained by radical polymerization of acrylic monomers by heating the droplets,
The droplet is heated by microwave irradiation, and the heating temperature T of the droplet at that time is the heating temperature at which the decomposition temperature T1 of the radical polymerization initiator and the desired mechanical properties of the acrylic polymer particles are obtained. An adjustment method characterized by adjusting the mechanical property level of the acrylic polymer particles by setting between T2 and T2.

  According to the production method or the adjustment method of the present invention, droplets of the monomer composition existing in the continuous phase are heated by microwave irradiation to radically polymerize the acrylic monomer. For this reason, the mechanical property level of acrylic polymer particles can be adjusted by controlling the heating temperature.

FIG. 3 is a diagram showing the relationship between the compression strength of the acrylic polymer particles of Example 1 and the polymerization time. 2 is a particle size distribution diagram of acrylic polymer particles of Example 1. FIG. 2 is a particle dispersion state photograph of acrylic polymer particles of Example 1. FIG. FIG. 4 is a relationship diagram between the compression strength of the acrylic polymer particles of Comparative Example 1 and the polymerization time. 2 is a particle size distribution diagram of acrylic polymer particles of Comparative Example 1. FIG. 2 is a particle dispersion state photograph of acrylic polymer particles of Comparative Example 1. It is a related figure of the compressive strength and polymerization temperature of the acrylic polymer particle of Example 2 and Comparative Example 2.

  The method for producing acrylic polymer particles of the present invention includes the following steps (a) and (b). Hereinafter, it demonstrates for every process.

<Process (a)>
First, a monomer composition containing an acrylic monomer and a radical polymerization initiator is discharged from the microchannel to the continuous phase, thereby forming droplets of the monomer composition in the continuous phase. This state is usually a liquid / liquid emulsion. Here, in order to discharge the monomer composition from the microchannel to the continuous phase, a known microreactor (see Japanese Patent Nos. 2975943, 2981547, 3616909, etc.) having a microchannel can be used. Commercially available microreactor devices can also be used. The microchannel applicable to these microreactor devices is not particularly limited, and for example, a microsyringe or a microchannel chip in which a groove is formed by etching on a glass substrate can be used.

  In addition, by appropriately selecting the groove width, groove depth, groove length, groove inner wall material, discharge pressure, type of dispersion medium constituting the continuous phase, dispersant, etc., the size of the droplets of the monomer composition Can be adjusted. Usually, the size of the droplet is 1 to 100 μm. This size is the final acrylic polymer particle size.

  As the acrylic monomer, monofunctional (meth) acrylate (here, (meth) acrylate includes acrylate and methacrylate) and bifunctional or higher polyfunctional (meth) acrylate can be used. By using polyfunctional (meth) acrylate, acrylic polymer particles can be made thermosetting.

  Monofunctional (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) ) Acrylate, t-butyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, 2-methylhexyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, 2-butylhexyl (meth) acrylate, isooctyl (meth) acrylate, isopentyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, cyclohexyl (meth) ) Acrylate, benzyl (meth) acrylate, phenoxy (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate, etc. Can be mentioned. Bifunctional (meth) acrylates include bisphenol F-EO-modified di (meth) acrylate, bisphenol A-EO-modified di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, and tricyclodecanedi. Examples include methylol di (meth) acrylate and dicyclopentadiene (meth) acrylate. Examples of the trifunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, trimethylolpropane PO-modified (meth) acrylate, and isocyanuric acid EO-modified tri (meth) acrylate. Examples of tetrafunctional or higher functional (meth) acrylates include dipentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetraacrylate. In addition, polyfunctional urethane (meth) acrylates can also be used. Specific examples include M1100, M1200, M1210, M1600 (above, Toa Gosei Co., Ltd.), AH-600, AT-600 (above, Kyoeisha Chemical Co., Ltd.), and the like.

  The radical polymerization initiator is a compound that generates radicals upon heating, and examples thereof include azo compounds and organic peroxides. Examples of the azo compound include azobisalkanonitrile. Examples of the organic peroxide include diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, and hydroperoxide. “Decomposition temperature” is an important indicator for selecting a radical polymerization initiator from these. As this temperature is lower, the low temperature rapid curability of the monomer composition tends to be improved. In the present specification, the decomposition temperature of the radical polymerization initiator specifically means a 10-hour half-life temperature.

  Specific examples of the radical polymerization initiator that can be used in the present invention include azobisisobutyronitrile (decomposition temperature 65 ° C.), diisobutyryl (decomposition temperature 32.7 ° C.), 1,1,3,3-tetramethylbutylperoxide. Oxy-2-ethylhexanoate (decomposition temperature 65.3 ° C), dilauroyl peroxide (decomposition temperature 61.6 ° C), di (3,5,5-trimethylhexanoyl) peroxide (decomposition temperature 59. 4 ° C.), t-butyl peroxypivalate (decomposition temperature 54.6 ° C.), t-hexyl peroxypivalate (decomposition temperature 53.2 ° C.), t-butyl peroxyneoheptanoate (decomposition temperature 50. 6 ° C), t-butylperoxyneodecanoate (decomposition temperature 40.7 ° C), t-hexylperoxyneodecanoate (decomposition temperature 44.5 ° C) Di (2-ethylhexyl) peroxydicarbonate (decomposition temperature 43.6 ° C), di (4-tert-butylcyclohexyl) peroxydicarbonate (decomposition temperature 40.8 ° C), 1,1,3,3-tetra Methyl butyl peroxyneodecanoate (decomposition temperature 40.7 ° C), di-sec-butyl peroxydicarbonate (decomposition temperature 40.5 ° C), di-n-propyl peroxydicarbonate (decomposition temperature 40.3 ° C) ° C), cumylperoxyneodecanoate (decomposition temperature 36.5 ° C), di (4-methylbenzoyl) peroxide (decomposition temperature 70.6 ° C), di (3-methylbenzoyl) peroxide (decomposition temperature 73) .1 ° C.), dibenzoyl peroxide (decomposition temperature 73.6 ° C.), 1,1-di (t-butylperoxy) -2-methylcyclohexane (Decomposition temperature 83.2 ° C), 1,1-di (t-hexylperoxy) cyclohexane (decomposition temperature 87.1 ° C), 1,1-di (t-butylperoxy) cyclohexane (decomposition temperature 90. 7 ° C.), t-hexyl peroxybenzoate (decomposition temperature 99.4 ° C.), t-butyl peroxybenzoate (decomposition temperature 104.7 ° C.), methyl ethyl ketone peroxide (decomposition temperature 15-35 ° C.), cyclohexanone peroxide, Methylcyclohexanone peroxide, t-butyl hydroperoxide, t-amyl hydroperoxide (decomposition temperature 258 ° C.), t-hexyl hydroperoxide (decomposition temperature 116.4 ° C.), t-octyl hydroperoxide (decomposition temperature 150) ° C), 2,5-dimethyl-2,5-dihydroperoxyhex Sun (decomposition temperature 118 ° C.), cumene hydroperoxide (decomposition temperature 157.9 ° C.), diisopropylbenzene monohydroperoxide, diisopropylbenzene dihydroperoxide (decomposition temperature unknown ° C.), paramentane hydroperoxide (decomposition temperature 128. 0 ° C.). Two or more of these can be used in combination. Moreover, the cohesive force of acrylic polymer particle can be improved by using the peroxide which has a high decomposition temperature and has a phenyl ring.

  If the blending amount of the radical polymerization initiator with respect to the acrylic monomer is too small, curing tends to be insufficient, and if it is too large, the degree of polymerization tends to be low and mechanical properties tend to be lowered. Preferably it is 1-40 mass parts with respect to a part, More preferably, it is 2-20 mass parts.

  The monomer composition may contain a vinyl monomer or oligomer, a non-polymerizable polymer, an organic filler, an inorganic filler, a pigment, or the like as necessary.

  The continuous phase functions as a dispersion medium for the droplets of the monomer composition, and is usually obtained by dissolving a dispersant in water such as ion exchange water. The dispersing agent can be appropriately selected from known cationic, anionic, nonionic, and amphoteric surfactants according to the type of droplet size of the monomer composition.

  Examples of the anionic surfactant include soap (fatty acid sodium), monoalkyl sulfate, alkyl polyoxyethylene sulfate, alkylbenzene sulfonate, and monoalkyl phosphate. Examples of the cationic surfactant include alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt and the like. Examples of amphoteric surfactants include alkyl dimethylamine oxide and alkyl carboxybetaine. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, fatty acid sorbitan ester, alkyl polyglucoside, fatty acid diethanolamide, alkyl monoglyceryl ether and the like.

  The content of such a surfactant in the continuous phase is generally from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight.

  If necessary, a stabilizer may be added to the continuous phase in order to stabilize the dispersion state of the droplets of the monomer composition and the acrylic polymer particles that are the polymer. For example, water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxymethyl cellulose, starch, and gelatin, poorly water-soluble inorganic salts such as tricalcium phosphate, and the like can be contained.

  The content of such stabilizers in the continuous phase is generally 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

  In addition, known additives such as chelating agents (glycine, alanine, sodium ethylenediaminetetraacetate, etc.), pH buffering agents (sodium tripolyphosphate, potassium tetrapolyphosphate, etc.), sensitizers, viscosity modifiers, etc. You may make it contain.

<Step (b)>
Next, the droplets of the monomer composition in the continuous phase are heated to radically polymerize the acrylic monomer. In the present invention, the droplets of the monomer composition are heated by microwave irradiation. By changing the output of the microwave irradiation energy or the like, the heating temperature of the droplets of the monomer composition can be controlled, and thereby the mechanical property level of the acrylic polymer particles can be adjusted. The reason for this is that in the case of heating by microwave irradiation, it is recognized that both polymerization and depolymerization occur, but as the heating temperature rises, polymerization becomes more dominant than depolymerization, and the monomer composition of The mechanical properties of the polymer, for example, the compressive strength (particle hardness) can be changed (in other words, can be controlled) without changing the composition. In addition, as a microwave irradiation apparatus, a commercially available apparatus can be used.

  The heating temperature can be controlled by adjusting the output of the micro irradiation. In the heating temperature range, the heating temperature T of the droplets of the monomer composition is set between the decomposition temperature T1 of the radical polymerization initiator and the heating temperature T2 at which desired mechanical characteristics of the acrylic polymer particles are obtained. . This is because if the heating temperature T is lower than the decomposition temperature T1 of the radical polymerization initiator, radical polymerization does not proceed, and if it is heated to a temperature higher than T2, the intended mechanical properties cannot be obtained.

  Specific methods for determining the heating temperature T2 include a method of determining from the reaction temperature by DSC (differential scanning calorimetry).

  In addition, when focusing on 30% compressive strength as a mechanical property and using dilauroyl peroxide having a decomposition temperature T1 of 61.6 ° C. as a radical polymerization initiator, acrylic polymer particles when the heating temperature T is T1 The 30% compression strength is 30 to 35 MPa, and the 30% compression strength when T is T2 is preferably 60 to 100 MPa.

  The acrylic polymer particles thus obtained are usually suspended in a continuous phase and can be isolated by filtration, centrifugation, or the like.

  The method for producing acrylic polymer particles of the present invention described above has an aspect of an adjustment method for adjusting the mechanical property level of the acrylic polymer particles.

That is, in this adjustment method, a monomer composition containing an acrylic monomer and a polymerization initiator is discharged from the dispersed-phase microchannel to the dispersed medium flowing in the continuous-phase microchannel, thereby A method of adjusting mechanical properties of acrylic polymer particles obtained by forming droplets of a monomer composition therein and then heat-polymerizing the droplets,
Heating polymerization of the droplets is performed by microwave irradiation, and the heating temperature T of the droplets at that time is a heating temperature at which the decomposition temperature T1 of the polymerization initiator and desired mechanical characteristics of the acrylic polymer particles are obtained. It is an adjustment method characterized by adjusting the mechanical property level of the acrylic polymer particles by setting between T2 and T2.

  The method for adjusting the mechanical property level of the acrylic polymer particles includes the following steps (aa) and (bb).

<Process (aa)>
First, a monomer composition containing an acrylic monomer and a radical polymerization initiator is discharged from the microchannel to the continuous phase, thereby forming droplets of the monomer composition in the continuous phase. This step has basically the same significance as step (a) of the production method of the present invention described above.

<Process (bb)>
Next, the droplets of the monomer composition in the continuous phase are heated by microwave irradiation to radically polymerize the acrylic monomer. This step has basically the same significance as step (b) of the production method of the present invention described above. Accordingly, the heating temperature T of the droplets during heating by microwave irradiation is between the decomposition temperature T1 of the radical polymerization initiator and the heating temperature T2 at which the desired mechanical properties of the acrylic polymer particles are obtained. By setting, the mechanical property level of the acrylic polymer particles is adjusted.

  Hereinafter, the present invention will be specifically described by way of examples.

Example 1 (microwave polymerization)
As dispersed phase, 75 parts by mass of ethylene glycol dimethacrylate (Light SEG EG, Kyoeisha Chemical Co., Ltd.) and 25 parts by mass of 1,6-hexamethylenediyl dimethacrylate (AH600, Kyoeisha Chemical Co., Ltd.) A monomer composition comprising 1 part by mass of dilauroyl peroxide (Perroyl L, NOF Corporation) was prepared. In addition, as a continuous phase, an aqueous solution (continuous phase solution) in which a surfactant (SDS, Wako Pure Chemical Industries, Ltd.) was dissolved in ion exchange water at a ratio of 1% by mass was prepared.

  The prepared dispersed phase and continuous phase are applied to a microreactor (Eptec Co., Ltd.) equipped with a microchannel (width 5 μm, depth 1 μm, length 100 μm), the dispersed phase is extruded into the continuous phase, and the average diameter Droplets of 3 μm monomer composition were formed. While mixing the resulting mixture, ion-exchanged water and a surfactant (SDS, Wako Pure Chemical Industries, Ltd.) were added, and the droplet concentration of the monomer composition was 2% by mass, and the surfactant concentration was 1. A slurry having a mass% was prepared.

  100 mL of the obtained slurry was put into a 200 mL separable flask, set in a microwave reactor (MWO-100S, Tokyo Rika Kikai Co., Ltd.) capable of emitting 2450 ± 30 MHz microwave, and nitrogen was supplied at a flow rate of 50 mL / Bubbling at min for 30 minutes, then the slurry was heated to 70 ° C. at a rate of 4 ° C./min, further heated to 90 ° C. at a rate of 2 ° C./min and maintained at 90 ° C., and radical polymerization of the acrylic monomer was performed. went. Sampling of the polymer was performed at the time when the temperature reached 90 ° C. (0 minutes), and then when 5 minutes, 15 minutes, 30 minutes, 60 minutes, 120 minutes, and 180 minutes had elapsed.

<10%, 30% compression strength measurement>
The 10% and 30% compressive strength (MPa) of the acrylic polymer particles in the sampled polymer was measured using a micro compression tester (MCMT-200: Shimadzu Corporation). The obtained results are shown in FIG. Paying attention to the result of 30% compressive strength in FIG. 1, it can be seen that the compressive strength is almost constant after 60 minutes.

<Measurement of particle size distribution and particle dispersion>
FIG. 2 shows a particle size distribution diagram of the sampled polymer obtained by measuring the particle size distribution of the acrylic polymer particles using a particle size distribution analyzer (SD-2000, manufactured by Sysmex Corporation). FIG. 2 shows that acrylic polymer particles having a monodisperse particle size can be obtained by the production method of the present invention.

<Particle dispersion measurement>
The sampled polymer was measured for particle dispersion of acrylic polymer particles using a particle dispersion measuring machine (FPIA-3000, manufactured by Sysmex Corporation), and the obtained results are shown in FIG. FIG. 3 shows that acrylic polymer particles with very little aggregation can be obtained by the production method of the present invention.

Comparative Example 1 (thermal polymerization)
As in Example 1, a slurry having a monomer composition droplet concentration of 2 mass% and a surfactant concentration of 1 mass% was prepared.

  100 mL of the resulting slurry is placed in a 200 mL separable flask, set in a heating block, nitrogen is bubbled at a flow rate of 50 mL / min for 30 minutes, and then the slurry is maintained at 80 ° C. for 1 hour, followed by 90 ° C., Radical polymerization of acrylic monomers was performed. Sampling of the polymer was performed at the time when the temperature reached 90 ° C. (0 minutes), and then when 5 minutes, 15 minutes, 30 minutes, 60 minutes, 120 minutes, and 180 minutes had elapsed. In addition, by sampling at 0, 5, 15, and 30 minutes, the polymerization was insufficient, and the polymerization solid could not be separated by filtration.

<10%, 30% compression strength measurement>
10% and 30% compressive strength (MPa) of acrylic polymer particles in the sampled polymer were measured using a micro compression tester (MCMT-200, Shimadzu Corporation). The obtained results are shown in FIG. Focusing on the result of 30% compression strength in FIG. 4, it can be seen that the compression strength is substantially constant after 1 hour.

<Measurement of particle size distribution and particle dispersion>
FIG. 5 shows a particle size distribution diagram of the sampled polymer obtained by measuring the particle size distribution of the acrylic polymer particles using a particle size distribution analyzer (SD-2000, manufactured by Sysmex Corporation). FIG. 5 shows that polymer particles corresponding to the second peak are formed in the thermal polymerization using the heat block.

<Particle dispersion measurement>
The sampled polymer was measured for particle dispersion of acrylic polymer particles using a particle dispersion measuring machine (FPIA-3000, manufactured by Sysmex Corporation). The obtained result is shown in FIG. From FIG. 6, it can be seen that acrylic polymer particles with very high aggregation can be obtained by thermal polymerization using a heat block.

Example 2 (microwave polymerization) and Comparative Example 2 (thermal polymerization)
As in Example 1, a slurry having a monomer composition droplet concentration of 2 mass% and a surfactant concentration of 1 mass% was prepared.

  In the case of Example 2, 100 mL of the obtained slurry was put into a 200 mL separable flask, a microwave of 2450 ± 30 MHz was set in a reactor (MWO-100S, Tokyo Rika Kikai Co., Ltd.), and nitrogen was supplied at a flow rate of 50 mL / Bubbling at min for 30 minutes, then the slurry was heated to 50 ° C. at a rate of 4 ° C./min, and further heated to a temperature of Table 1 at a rate of 2 ° C./min, and the temperature was maintained. Polymerization was performed. Sampling of the polymer was performed when 5 hours had passed after reaching the temperature in Table 1.

  In the case of Comparative Example 2, 100 mL of the obtained slurry was put into a 200 mL separable flask, set in a heating block, nitrogen was bubbled at a flow rate of 50 mL / min for 30 minutes, and the slurry was then heated at the temperature shown in Table 1 for 8 hours each. It heated and the radical polymerization of the acryl-type monomer was performed. After the polymerization was completed, the polymer was sampled.

<10%, 30% compression strength measurement>
The 30% compressive strength (MPa) of the acrylic polymer particles in the sampled polymer was measured using a micro compression tester (MCMT-200, Shimadzu Corporation). The obtained results are shown in Table 1 and FIG. From Table 1 and FIG. 7, it can be seen that the 30% compressive strength of Comparative Example 2 (radical polymerization by heating a heat block) has low temperature dependency. On the other hand, it can be seen that the 30% compressive strength in Example 2 (radical polymerization by microwave irradiation heating) is highly temperature dependent. Therefore, according to the present invention, it is understood that the compressive strength can be controlled by changing the polymerization temperature in the microwave irradiation heating. Moreover, it turns out that temperature T2 in the case of Example 2 is 90 degreeC.

  According to the production method or the adjustment method of the present invention, droplets of the monomer composition existing in the continuous phase are heated by microwave irradiation to radically polymerize the acrylic monomer. For this reason, the mechanical property level of acrylic polymer particles can be adjusted by controlling the heating temperature. Therefore, the production method or the adjustment method of the present invention can be preferably applied when it is desired to change the mechanical properties of the polymer particles to be produced without changing the blend composition of the monomer composition.

Claims (6)

A monomer composition containing an acrylic monomer and a radical polymerization initiator is discharged from the microchannel to the continuous phase, thereby forming droplets of the monomer composition in the continuous phase, and then heating the droplets. A method for producing acrylic polymer particles by radical polymerization of acrylic monomers,
The droplet is heated by microwave irradiation, and the heating temperature T of the droplet at that time is the heating temperature at which the decomposition temperature T1 of the radical polymerization initiator and the desired mechanical properties of the acrylic polymer particles are obtained. The manufacturing method characterized by adjusting the mechanical property level of an acrylic polymer particle by setting between T2.   The manufacturing method according to claim 1, wherein the mechanical property is compressive strength.   The 30% compressive strength of the acrylic polymer particles when the heating temperature T is T1 is 30 to 35 MPa, and the 30% compressive strength of the acrylic polymer particles when the heating temperature T is T2 is 60 to 100 MPa. Production method. A monomer composition containing an acrylic monomer and a radical polymerization initiator is discharged from the microchannel to the continuous phase, thereby forming droplets of the monomer composition in the continuous phase, and then heating the droplets A method for adjusting the mechanical properties of acrylic polymer particles obtained by radical polymerization of acrylic monomers,
The droplet is heated by microwave irradiation, and the heating temperature T of the droplet at that time is the heating temperature at which the decomposition temperature T1 of the radical polymerization initiator and the desired mechanical properties of the acrylic polymer particles are obtained. The adjustment method characterized by adjusting the mechanical characteristic level of an acrylic polymer particle by setting between T2.   The adjustment method according to claim 4, wherein the mechanical property is compressive strength.   The 30% compression strength of the acrylic polymer particles when the heating temperature T is T1 is 30 to 35 MPa, and the 30% compression strength of the acrylic polymer particles when the heating temperature T is T2 is 60 to 100 MPa. Adjustment method.