JP2011074289A - Manufacturing method of polymer particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polymer particle having a relatively large particle size even by the suspension polymerization method. <P>SOLUTION: The manufacturing method for a polymer particle comprises the steps of: preparing a polymerizable monomer composition containing at least one polymerizable monomer; suspending the polymerizable monomer composition in an aqueous medium containing a dispersion stabilizer to obtain a suspension liquid in which liquid droplets of the polymerizable monomer composition are dispersed; and suspension-polymerizing the suspension liquid in the presence of a polymerization initiator to obtain the polymer particle. In the suspension step of obtaining the suspension liquid, the dispersion stabilizer is a magnesium hydroxide particle having a number-average primary particle size of 0.5 to 10 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing polymer particles by a suspension polymerization method.

  Until now, as a method for producing polymer particles by suspension polymerization, it has been widely used in the technical field of toner. In recent years, in the technical field of toner, various attempts to reduce the particle size of the toner and adjust the particle size distribution more sharply as the requirement level for high-resolution and high-quality image printing increases. Has been made.

  In general, a toner prepared by a suspension polymerization method is prepared by first preparing a polymerizable monomer composition containing a polymerizable monomer, a colorant and the like, and then adding the polymerizable monomer composition to a dispersion stabilizer. By suspending in the aqueous dispersion medium to obtain a suspension in which droplets of the polymerizable monomer composition are dispersed, and subjecting the suspension to suspension polymerization in the presence of a polymerization initiator. Manufactured.

  In the toner production method by suspension polymerization, the particle size of the toner is generally determined by the droplet size of the polymerizable monomer composition formed in the step of obtaining the suspension. In order to control to a desired reduced particle size, various studies have been made on the type and amount of the dispersion stabilizer contained in the aqueous dispersion medium.

  For example, in Patent Document 1, as a dispersion stabilizer, 6.8 parts of sodium hydroxide was dissolved in 50 parts of ion-exchanged water in an aqueous magnesium chloride solution in which 7.4 parts of magnesium chloride were dissolved in 250 parts of ion-exchanged water. A method for producing a toner having a volume average particle diameter Dv of 6.6 to 6.8 μm using a colloidal dispersion of magnesium hydroxide prepared by adding an aqueous sodium hydroxide solution is described.

  In Patent Document 1, the colloidal dispersion of magnesium hydroxide prepared as a dispersion stabilizer was measured for the particle size distribution of the colloid with a SALD particle size distribution analyzer (manufactured by Shimadzu Corporation). It is described that D50 (50% cumulative value of the number particle size distribution) was 0.35 μm and D90 (90% cumulative value of the number particle size distribution) was 0.62 μm.

JP 2007-148033 A

  However, Patent Document 1 attempts to reduce the particle size of the toner by the suspension polymerization method, but a method for producing polymer particles having a relatively large particle size has not been studied at all. Not.

  In the technical field in which a polymer particle having a relatively large particle size with a volume average particle diameter Dv of 20 μm or more is expected (for example, the technical field of “microcapsule particles for heat storage material”), By further applying the technology cultivated in the technical field of toners so far, a method for producing highly versatile polymer particles was examined.

  The present invention has been accomplished in view of the above-described actual circumstances, and an object of the present invention is to provide a method capable of producing polymer particles having a relatively large particle size even by suspension polymerization. is there.

  As a result of diligent investigations to achieve the above object, the present inventors have included magnesium hydroxide particles having a specific particle size in an aqueous dispersion medium as a dispersion stabilizer in a suspension step for obtaining a suspension. Thus, it has been found that polymer particles having a relatively large particle size can be produced even by suspension polymerization, and the present invention has been completed based on these findings.

That is, the method for producing polymer particles of the present invention comprises a step of preparing a polymerizable monomer composition containing at least one polymerizable monomer, and the dispersion stabilization of the polymerizable monomer composition. A suspension step in which a suspension in which droplets of the polymerizable monomer composition are dispersed is suspended in an aqueous dispersion medium containing the agent, and the suspension is suspended in the presence of a polymerization initiator. A method for producing polymer particles comprising a step of obtaining polymer particles by suspension polymerization,
In the suspending step for obtaining the suspension, the dispersion stabilizer is magnesium hydroxide particles having a number average primary particle size of 0.5 to 10 μm.

  In the method for producing the polymer particles, in the step of preparing the polymerizable monomer composition, the polymerizable monomer composition contains a wax having a melting point of 5 to 150 ° C. as a heat storage material, It is preferable that content is 5-200 weight part with respect to 100 weight part of polymerizable monomers.

In the method for producing the polymer particles, in the step of preparing the polymerizable monomer composition, the polymerizable monomer composition contains a wax having a melting point of 5 to 150 ° C. as a heat storage material, When the content is 5 to 200 parts by weight with respect to 100 parts by weight of the polymerizable monomer,
The polymerizable monomer in the polymerizable monomer composition contains a crosslinkable polymerizable monomer, and the component ratio of the crosslinkable polymerizable monomer is 10 of the total amount of polymerizable monomers. It is preferable that it is weight% or more.

  In the method for producing polymer particles, in the suspending step of obtaining the suspension, the aqueous dispersion medium preferably contains magnesium chloride.

  According to the method for producing polymer particles of the present invention as described above, there is provided a method capable of producing polymer particles having a relatively large particle diameter even by suspension polymerization.

1 is a scanning electron microscope (SEM) photograph of the polymer particles obtained in Example 1. FIG. FIG. 2 is a scanning electron microscope (SEM) photograph of the polymer particles obtained in Example 4.

The method for producing polymer particles of the present invention comprises a step of preparing a polymerizable monomer composition containing at least one or more polymerizable monomers, and the polymerizable monomer composition is used as a dispersion stabilizer. A suspension process in which the droplets of the polymerizable monomer composition are dispersed to obtain a suspension in which the suspension is suspended in the presence of a polymerization initiator. A method for producing polymer particles comprising a step of obtaining polymer particles by polymerization,
In the suspending step for obtaining the suspension, the dispersion stabilizer is magnesium hydroxide particles having a number average primary particle size of 0.5 to 10 μm.

(1) Preparation process of polymerizable monomer composition In this process, at least one or more kinds of polymerizable monomers and, if necessary, other additives and the like are stirred, mixed, and uniformly dispersed. Thus, a polymerizable monomer composition is prepared.

According to the method for producing polymer particles of the present invention, a heat storage material can be contained in the polymerizable monomer composition as another additive. A polymerizable monomer composition is prepared by containing a heat storage material, and (2) a step of obtaining a suspension (droplet forming step), (3) a suspension polymerization step, (4) separation / Microcapsule particles for a heat storage material are obtained through washing, filtration, dehydration, and drying processes.
Here, “microcapsule particles for heat storage material” refers to capsule particles composed of a capsule wall and a heat storage material contained therein.
Hereinafter, an example of a method for producing “microcapsule particles for heat storage material” will be described.

  First, at least one or more kinds of polymerizable monomers constituting the resin that becomes the capsule wall are stirred, mixed and uniformly dispersed while keeping heat, then a heat storage material is added, stirred, mixed, dispersed or Dissolve to prepare a polymerizable monomer composition.

  Here, the temperature at which at least one kind of polymerizable monomer is kept warm is the component of the polymerizable monomer and the kind of the heat storage material from the viewpoint of easily dissolving the heat storage material in the polymerizable monomer. Although it adjusts suitably according to etc., it is preferable to set to 20-60 degreeC, and it is more preferable to set to 25-50 degreeC.

  In the present invention, from the viewpoint of forming a desired capsule wall, a polymerizable monomer containing a “crosslinkable polymerizable monomer” is used as the polymerizable monomer constituting the resin that becomes the capsule wall. Is preferred.

Here, the “crosslinkable polymerizable monomer” refers to a crosslinkable polymerizable monomer having two or more polymerizable functional groups in the molecule.
The polymerizable functional group is preferably a carbon-carbon unsaturated double bond (C = C).

  Examples of the “crosslinkable polymerizable monomer” include vinyl crosslinkable polymerizable monomers such as divinylbenzene, divinylbiphenyl, and divinylnaphthalene; allylic crosslinkable monomers such as diallyl phthalate and triallyl isocyanurate. Polymerizable monomer; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3 -(Meth) acrylic crosslinkable polymerizable monomers such as butylene glycol di (meth) acrylate and trimethylolpropane tri (meth) acrylate; These crosslinkable polymerizable monomers can be used alone or in combination of two or more.

  Among the above-mentioned crosslinkable polymerizable monomers, (meth) acrylic crosslinkable polymerizable monomers and vinyl crosslinkable polymerizable monomers are preferable because a suitable capsule wall is easily formed. A (meth) acrylic crosslinkable polymerizable monomer is more preferable, and ethylene glycol dimethacrylate is particularly preferable.

  In the present invention, the component ratio of the crosslinkable polymerizable monomer is preferably 10% by weight or more, and preferably 30% by weight or more of the total amount of the polymerizable monomer constituting the resin that becomes the capsule wall. More preferably, it is more preferably 50% by weight or more.

  When the component ratio of the crosslinkable polymerizable monomer is less than the above lower limit, the strength as the capsule wall cannot be sufficiently obtained, the capsule wall is easily broken, and the heat storage material is leaked. It may cause.

  Note that “leakage of heat storage material” here means that the capsule wall is destroyed and the heat storage material leaks to the outside, or the compatibility between the heat storage material and the resin constituting the capsule wall is too high. It refers to a problem that occurs when it is no longer possible to maintain a state in which a heat storage material is suitably included, such as when heat storage exudes from the outside.

  In the present invention, a “monofunctional polymerizable monomer” can be used in combination with a “crosslinkable polymerizable monomer” as the polymerizable monomer constituting the resin that becomes the capsule wall. .

Here, the “monofunctional polymerizable monomer” refers to a polymerizable monomer having only one polymerizable functional group in the molecule.
The polymerizable functional group is preferably a carbon-carbon unsaturated double bond (C = C).

  Examples of the “monofunctional polymerizable monomer” include monovinyl aromatic monofunctional polymerizable monomers such as styrene, vinyl toluene and α-methylstyrene; (meth) acrylic acid, (meth) acrylic acid (Meth) acrylic monofunctional such as methyl, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, etc. Polymerizable monomers; olefinic monofunctional polymerizable monomers such as ethylene, propylene, butylene; and the like. These monofunctional polymerizable monomers can be used alone or in combination of two or more.

  Among the monofunctional polymerizable monomers, monovinyl aromatic monofunctional polymerizable monomers and (meth) acrylic monofunctional polymerizable monomers can be obtained because a suitable capsule wall is easily formed. Are preferably used, and styrene and methyl methacrylate are particularly preferable.

  In the present invention, the component ratio of the monofunctional polymerizable monomer is preferably 90% by weight or less, and preferably 70% by weight or less, based on the total amount of the polymerizable monomer constituting the resin that becomes the capsule wall. More preferably, the content is 10% by weight or more and 50% by weight or less.

  The heat storage material is not particularly limited as long as it is generally used as a heat storage material, but has a specific melting point (Tm) (phase transition temperature of the heat storage material) because a desired heat storage effect is easily obtained. It is preferable to use a specific amount of wax.

  As the wax used as the heat storage material in the present invention, for example, polypropylene wax, polyethylene wax, petroleum wax, Fischer-Tropsch wax, polyfunctional fatty acid ester compound and the like are representatively mentioned, and polyfunctional fatty acid ester compounds are preferably used.

  Here, the “polyfunctional fatty acid ester compound” means that the carboxyl group (—COOH) of “higher fatty acid (R—COOH)” and the hydroxyl group (—OH) of “polyhydric alcohol (R′—OH)” are dehydrated. An ester compound having two or more ester bonds (R—COO—R ′) formed by condensation in the molecule.

  “Higher fatty acid (R-COOH)” as a raw material of “polyfunctional fatty acid ester compound” means a fatty acid having 12 or more carbon atoms, and is a linear saturated higher fatty acid, linear unsaturated higher fatty acid, branched saturated Broadly classified into higher fatty acids and branched unsaturated higher fatty acids. Of these, linear saturated higher fatty acids are preferably used.

Examples of such linear saturated higher fatty acids include lauric acid (C ₁₂ ), myristic acid (C ₁₄ ), palmitic acid (C ₁₆ ), stearic acid (C ₁₈ ), arachidic acid (C ₂₀ ), and behenic acid. (C ₂₂ ), lignoceric acid (C ₂₄ ), serotic acid (C ₂₆ ), montanic acid (C ₂₈ ), melicic acid (C ₃₀ ) and the like.

The “higher fatty acid (R—COOH)” used as a raw material for these “polyfunctional fatty acid ester compounds” can be used alone or in combination of two or more.
Among these, since a desired heat storage effect can be easily obtained, a linear saturated higher fatty acid having 12 to 28 carbon atoms is preferably used, and a linear saturated higher fatty acid having 12 to 22 carbon atoms is more preferably used. A linear saturated higher fatty acid having 14 to 18 carbon atoms is more preferably used.

  “Polyhydric alcohol (R′—OH)” as a raw material of “polyfunctional fatty acid ester compound” refers to a divalent or higher alcohol having two or more hydroxyl groups (—OH) in the molecule.

  Examples of the dihydric alcohol include ethylene glycol, neopentyl glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexane. Examples include dimethanol.

  Examples of the trihydric alcohol include glycerin, trimethylolpropane, 1,2,4-butanetriol, and 1,2,6-hexanetriol.

  Examples of the tetrahydric alcohol include diglycerin, pentaerythritol, ditrimethylolpropane, and tetrahydroxycyclohexane.

  Examples of the pentahydric alcohol include triglycerin, xylitol, arabitol, and pentahydroxybenzene.

  Examples of the hexavalent alcohol include dipentaerythritol, tetraglycerin, sorbitol, and mannitol.

  Examples of the 7-valent alcohol include pentaglycerin and the like.

  Examples of the octahydric alcohol include sucrose, hexaglycerin, and tripentaerythritol.

The “polyhydric alcohol (R′—OH)” used as a raw material for these “polyfunctional fatty acid ester compounds” can be used alone or in combination of two or more.
Among these, since a desired heat storage effect can be easily obtained, a polyhydric alcohol having a valence of 4 or more is preferably used, and a polyhydric alcohol having a valence of 6 or more is more preferably used. Among them, dipentaerythritol and hexaglycerin are preferable. Is particularly preferably used.

In the present invention, the melting point (Tm) of the wax preferably used as the heat storage material (phase transition temperature of the heat storage material) is preferably 5-150 ° C, more preferably 10-120 ° C, and more preferably 20-80. It is still more preferable that it is ° C.
Here, the “melting point (Tm)” refers to a value defined as the temperature at the top of a peak in a DSC curve by a differential scanning calorimeter (DSC).

  The melting point (Tm) of the wax preferably used as the heat storage material is a value measured using a differential scanning calorimeter. For example, a differential scanning calorimeter (model name: EXSTAR DSC) manufactured by Seiko Instruments Inc. 6220).

  When the melting point (Tm) of the wax (phase transition temperature of the heat storage material) is less than the lower limit, it may be difficult to obtain an endothermic reaction effect associated with the phase transition of the heat storage material. On the other hand, when the melting point (Tm) of the wax (phase transition temperature of the heat storage material) exceeds the above upper limit, it may be difficult to obtain the effect of the exothermic reaction accompanying the phase transition of the heat storage material.

  In the present invention, the number average molecular weight (Mn) of the wax preferably used as the heat storage material is preferably 1,300 to 4,000, more preferably 1,400 to 3,000, 1,500. More preferably, it is -2,000.

  If the number average molecular weight (Mn) of the wax is less than the above lower limit, the compatibility between the resin forming the capsule wall and the heat storage material becomes too high, especially when exposed to a high temperature environment for a long time. In some cases, leakage of the material is likely to occur. On the other hand, when the number average molecular weight (Mn) of the wax exceeds the upper limit, in the preparation step of the polymerizable monomer composition, the polymerizable monomer and the heat storage material constituting the resin that becomes the capsule wall In some cases, the compatibility is too low, the capsule wall cannot be suitably formed, and the heat storage material is likely to leak.

  In the present invention, the weight average molecular weight (Mw) of the wax preferably used as the heat storage material is preferably 1,300 to 12,000, more preferably 1,400 to 8,000, and 1,500. More preferably, it is -3,000.

  When the weight average molecular weight (Mw) of the wax is less than the above lower limit, the compatibility between the resin forming the capsule wall and the heat storage material becomes too high, and particularly when exposed to a high temperature environment for a long time, the heat storage In some cases, leakage of the material is likely to occur. On the other hand, when the weight average molecular weight (Mw) of the wax exceeds the upper limit, in the preparation step of the polymerizable monomer composition, the polymerizable monomer and the heat storage material constituting the resin that becomes the capsule wall In some cases, the compatibility is too low, the capsule wall cannot be suitably formed, and the heat storage material is likely to leak.

  In the present invention, the molecular weight distribution (Mw / Mn), which is the ratio of the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the wax preferably used as a heat storage material, is preferably 1 to 3, 2 is more preferable, and 1 to 1.5 is still more preferable.

  When the molecular weight distribution (Mw / Mn) of the wax exceeds the above upper limit, the low molecular weight component of the heat storage material is likely to exude from the capsule wall to the outside, and the state in which the heat storage material is suitably included is maintained. Can be difficult.

  In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the wax preferably used as the heat storage material are measured by a gel permeation chromatograph (GPC) method using a GPC measuring apparatus, and are calculated in terms of polystyrene. For example, it can be measured using a GPC measuring device (trade name: HLC-8220GPC) manufactured by Tosoh Corporation.

  In the present invention, the content of the wax preferably used as the heat storage material is preferably 5 to 200 parts by weight with respect to 100 parts by weight of the polymerizable monomer constituting the resin serving as the capsule wall. More preferred are parts by weight, and even more preferred is 30 to 120 parts by weight.

  When the content of the wax is less than the lower limit, the function as the heat storage material cannot be sufficiently exhibited, and the heat storage performance may be inferior. On the other hand, when the content of the wax exceeds the upper limit, the heat storage material becomes difficult to dissolve in the polymerizable monomer in the preparation step of the polymerizable monomer composition, and the capsule wall is suitably formed. In some cases, leakage of the heat storage material is likely to occur.

(2) Step of obtaining a suspension (droplet forming step)
In this step, the dispersion stabilizer specified in the present invention (magnesium hydroxide particles having a number average particle size of 0.5 to 10 μm) is contained in the aqueous dispersion medium, and a dispersion stabilizer dispersion is prepared. In the prepared dispersion, the polymerizable monomer composition obtained by the step (1) of preparing the polymerizable monomer composition is suspended to prepare the polymerizable monomer composition. A suspension (polymerizable monomer composition dispersion) in which droplets are dispersed is obtained.
Here, “suspension” means forming droplets of the polymerizable monomer composition in an aqueous dispersion medium.

  In this step, the dispersion of the dispersion stabilizer specified in the present invention (magnesium hydroxide particles having a number average particle size of 0.5 to 10 μm) in the aqueous dispersion medium is improved to uniformly disperse the magnesium hydroxide. From the viewpoint of shortening the time required for the dispersion and suitably preparing a dispersion of the dispersion stabilizer, it is preferable to contain magnesium chloride in the aqueous dispersion medium.

  In the present invention, a method for preparing a dispersion of a dispersion stabilizer by incorporating the dispersion stabilizer specified in the present invention in an aqueous dispersion medium is not particularly limited. For example, a stirring blade is provided. In a stirring tank, a method in which the dispersion stabilizer specified in the present invention is gradually added to a magnesium chloride aqueous solution in which magnesium chloride is dissolved in an aqueous dispersion medium in advance while stirring to uniformly disperse it.

  As the aqueous dispersion medium, water alone may be used, but a solvent that is soluble in water, such as lower alcohol and lower ketone, may be used in combination.

Examples of the stirring blades provided in the stirring tank include inclined paddle blades, flat paddle blades, propeller blades, anchor blades, fiddler blades, turbine blades, bull margin blades, Max Blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), and full zone blades. (Made by Shinko Pantech Co., Ltd.), ribbon wing, supermix wing (made by Sumitomo Heavy Industries, Ltd.), A310 wing (made by LIGHTTIN), A320 (made by LIGHTTIN), intermig wing (made by Ecart) .
Among these stirring blades, inclined paddle blades are preferably used because the dispersion stabilizer specified in the present invention is easily dispersed uniformly.

  In the present invention, the method for forming droplets of the polymerizable monomer composition in the dispersion of the dispersion stabilizer prepared as described above is not particularly limited. Into the dispersion of the agent, the polymerizable monomer composition is charged, stirred until the droplets are stabilized, a polymerization initiator is added, and the mixture is stirred by high shear using a device capable of strong stirring. A method for forming droplets is mentioned.

  As an apparatus capable of strong stirring, for example, an in-line type emulsifying disperser (manufactured by Ebara Manufacturing Co., Ltd., trade name: Ebara Milder MDN303V), a high-speed emulsifying / dispersing machine (manufactured by Special Machine Industries, Ltd., trade name: TK Homomixer MARK type II) and the like.

  In the present invention, a polymerizable monomer composition having a desired diameter in an aqueous dispersion medium by using magnesium hydroxide particles having a number average primary particle diameter of 0.5 to 10 μm as a dispersion stabilizer. The droplets can be stably formed, and polymer particles having a relatively large particle size can be produced by suspension polymerization.

  The magnesium hydroxide particles having a number average primary particle size of 0.5 to 10 μm used as a dispersion stabilizer in the present invention are maintained as they are in an aqueous dispersion medium, and are 0.5 to 10 μm. is there.

  In the present invention, the number average primary particle size of the magnesium hydroxide particles used as the dispersion stabilizer is 0.5 to 10 μm, preferably 0.6 to 8 μm, more preferably 0.7 to 5 μm, still more preferably. 0.8-4 μm.

  When the number average primary particle size of the magnesium hydroxide particles is less than the lower limit, droplets are easily reduced in the aqueous dispersion medium, and only polymer particles having a relatively small particle size can be obtained. There may not be. On the other hand, when the number average primary particle size of the magnesium hydroxide particles exceeds the upper limit, only an aggregated polymer may be obtained.

  In the present invention, various commercially available products can be used as the magnesium hydroxide particles used as the dispersion stabilizer. For example, “Kisuma 5Q-S” (trade name, number average primary particles manufactured by Kyowa Chemical Industry Co., Ltd.). Diameter: 1 μm); “UD653” manufactured by Ube Material (trade name, number average primary particle size: 3.1 μm); “Echo Mug PZ-1” manufactured by Tateho Chemical Co., Ltd. (: product name, number average primary particle size) : 1.2 μm);

  In the present invention, the magnesium hydroxide particles used as a dispersion stabilizer are preferably 2 to 25 parts by weight, more preferably 4 to 20 parts by weight, still more preferably 5 to 5 parts by weight with respect to 100 parts by weight of the polymerizable monomer. It is used at a ratio of 15 parts by weight.

  When the amount of magnesium hydroxide particles used is less than the lower limit, the effect of uniformly dispersing the polymerizable monomer composition in the aqueous dispersion medium cannot be sufficiently obtained, and the droplets are stabilized. In some cases, only an aggregated polymer can be obtained. On the other hand, when the amount of the magnesium hydroxide particles exceeds the upper limit, the effect of uniformly dispersing the polymerizable monomer composition in the aqueous dispersion medium is excessively advanced, and the droplets are small. In some cases, only polymer particles having a relatively small particle diameter can be obtained.

(3) Suspension polymerization step In this step, the suspension obtained by the suspension step (2) to obtain a suspension is heated in the presence of a polymerization initiator to cause suspension polymerization. An aqueous dispersion of polymer particles is obtained.

  In the present invention, the timing of adding the polymerization initiator is not particularly limited. For example, the polymerization initiator is directly added to the polymerizable monomer composition in the previous stage where droplets of the polymerizable monomer composition are formed. Alternatively, the polymerizable monomer composition may be added to the dispersion liquid of the dispersion stabilizer and added after stirring until the droplets of the polymerizable monomer composition are stabilized. .

  Examples of the polymerization initiator include inorganic persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methyl-N— (2-hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobisisobuty Azo compounds such as nitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy Pivalate, diisopropyl peroxydicarbonate, di-t-butylperoxyisophthalate, and t-butylperoxyisobutyl Organic peroxides rate, etc.;., Etc. Among these, organic peroxides are preferably used.

  The addition amount of the polymerization initiator is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of the polymerizable monomer, and 1.0 More preferably, it is 10 weight part.

Although the temperature of suspension polymerization is not specifically limited, It is preferable that it is 50-100 degreeC, and it is more preferable that it is 60-95 degreeC.
The time required for suspension polymerization varies depending on the components of the polymerizable monomer and the kind of the polymerization initiator, but is preferably 1 to 20 hours, and more preferably 2 to 15 hours.

  In order to perform suspension polymerization in a state in which the droplets of the polymerizable monomer composition are stably dispersed, stirring in the step (2) obtaining the suspension (droplet formation step) is also performed in this step. The polymerization reaction may be allowed to proceed while carrying out the dispersion treatment.

(4) Separation / Washing, Filtration, Dehydration, and Drying Step In this step, the aqueous dispersion of polymer particles obtained by the above (3) suspension polymerization step is subjected to a series of separation / washing, filtration, and dehydration. The above operation is repeated several times as necessary, and the obtained solid content is dried to obtain polymer particles.

  In the aqueous dispersion of polymer particles obtained in the above (3) suspension polymerization step, the dispersion stabilizer specified in the present invention remains, so that the aqueous dispersion of polymer particles is stirred while the acid is stirred. The pH is preferably adjusted to 6.5 or less, more preferably 6.0 or less, and the dispersion stabilizer remaining in the aqueous dispersion of polymer particles is removed by dissolving with acid. It is preferable to perform washing.

  As the acid dropped into the aqueous dispersion of polymer particles, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. However, the dispersion stabilizer specified in the present invention is removed. An inorganic acid is preferably used because of its high efficiency and a small burden on manufacturing equipment, and sulfuric acid is more preferably used.

(Polymer particles)
In the method for producing polymer particles of the present invention, in the suspending step of obtaining a suspension, magnesium hydroxide particles having a number average primary particle size of 0.5 to 10 μm are used as a dispersion stabilizer, thereby producing an aqueous system. It is possible to stably form droplets of a polymerizable monomer composition having a desired diameter in a dispersion medium, and to produce polymer particles having a relatively large particle diameter even by suspension polymerization. Can do.

  According to the method for producing polymer particles of the present invention, in the step (1) of preparing the polymerizable monomer composition, the polymerizable monomer composition contains a heat storage material, A body composition is prepared, and after the above-described (2) step of obtaining a suspension (droplet formation step), (3) suspension polymerization step, (4) separation / washing, filtration, dehydration, and drying steps, A relatively large particle size microcapsule particle for a heat storage material can be produced.

(Microcapsule particles for heat storage materials)
Hereinafter, the particle size characteristics of the microcapsule particles for the heat storage material will be described.
In the present invention, the volume average particle size (Dv) of the microcapsule particles for heat storage material is preferably 20 to 200 μm, more preferably 20 to 100 μm, and still more preferably 25 to 80 μm.

  When the volume average particle diameter (Dv) of the microcapsule particles for heat storage material is less than the lower limit, not only is it difficult to produce by suspension polymerization, but the heat storage persistence is poor due to an increase in surface area. There is a case. On the other hand, when the volume average particle diameter (Dv) of the microcapsule particles for the heat storage material exceeds the upper limit, the capsule wall becomes relatively thin, so that the capsule wall is likely to be damaged, and the heat storage material is leaked. It may be likely to occur.

  The particle size distribution (Dv / Dn), which is the ratio of the volume average particle size (Dv) and the number average particle size (Dn), of the microcapsule particles for heat storage material is preferably 1.0 to 1.3, It is more preferable that it is 1.0-1.25.

  When the particle size distribution (Dv / Dn) of the microcapsule particles for the heat storage material exceeds the upper limit, the proportion of the small particle size increases and the heat storage persistence may deteriorate as described above. .

  In addition, the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the microcapsule particles for the heat storage material are values measured using a particle size measuring machine, for example, particles manufactured by Beckman Coulter, Inc. It can be measured using a diameter measuring machine (trade name: Multisizer).

  The average circularity of the microcapsule particles for a heat storage material is preferably 0.94 to 0.995, more preferably 0.95 to 0.995, and 0.96 to 0.995. Further preferred.

The latent heat quantity (Q) of the microcapsule particles for heat storage material produced by the method for producing polymer particles of the present invention is preferably 10 J / g or more, and more preferably 15 J / g or more.
The latent heat (Q) of the microcapsule particles for the heat storage material is a value measured using a differential scanning calorimeter, for example, a differential scanning calorimeter (model name: EXSTAR DSC) manufactured by Seiko Instruments Inc. 6220).

  When the amount of latent heat (Q) of the microcapsule particles for heat storage material is less than the lower limit, the function as the heat storage material cannot be sufficiently exhibited, and the heat storage performance may be inferior.

  As mentioned above, although the manufacturing method of the polymer particle containing a heat storage material was demonstrated, even when it does not contain a heat storage material, the polymer particle which does not contain a heat storage material is manufactured with the manufacturing method similar to the above except except a heat storage material. can do.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to these examples. Parts and% are based on weight unless otherwise specified.
The test methods performed in the examples and comparative examples are as follows.

(1) Dispersion Stabilizer (1-1) Number Average Primary Particle Size The number average primary particle size of the dispersion stabilizer is obtained by taking an electron micrograph of each particle, and using the photograph as an image processing analyzer (manufactured by Nireco). , Product name: Luzex IID), calculating the equivalent circle diameter corresponding to the projected area of the particle under the condition of the particle area ratio to the frame area: 2% at the maximum and the total number of treated particles: 100, and the arithmetic mean The value of was obtained.

(2) Melting point (Tm) of heat storage material
A measurement sample (heat storage material) is weighed in an amount of 6 to 8 mg in a sample holder, and is measured from −20 ° C. to 100 ° C. using a differential scanning calorimeter (Seiko Instruments, model name: EXSTAR DSC 6220). The measurement was performed under the condition of increasing the temperature at ° C./min, and a DSC curve was obtained. The top of the peak of the DSC curve was determined as the melting point (Tm).

(3) Particle size characteristics of polymer particles (3-1) Volume average particle size (Dv)
About 0.1 g of polymer particles are weighed, taken into a beaker, 0.1 ml of an alkylbenzene sulfonic acid aqueous solution (manufactured by Fuji Film Co., Ltd., trade name: Drywell) is added as a dispersant, and a dedicated electrolyte (Beckman Coulter, Inc.) is added. , Trade name: Isoton II-PC) is added to 10 to 30 ml, and after dispersion with an ultrasonic disperser for 20 W for 3 minutes, using a particle size measuring machine (Beckman Coulter, trade name: Multisizer). , Aperture diameter: 100 μm, medium: Isoton II-PC, number of measured particles: volume average particle diameter (Dv) of polymer particles was measured under conditions of 100,000.

(3-2) Scanning Electron Microscope (SEM) Observation Platinum deposition is performed on polymer particles, and an acceleration voltage is set to 5 kV using a field emission scanning electron microscope (trade name: S-4700, manufactured by Hitachi, Ltd.). The surface shape of the polymer particles was observed by 5,000 times magnification.

(4) Latent heat quantity of microcapsule particles for heat storage material (J / g)
A precisely weighed measurement sample (microcapsule particles for heat storage material) was introduced into a differential scanning calorimeter (manufactured by Seiko Instruments Inc., model name: EXSTAR DSC 6220), and the rate of temperature increase: 10 ° C./min, temperature range: 0 Measurements were performed at a temperature of from -100 ° C to obtain a DSC curve.
The integrated value of the difference between the obtained DSC curve and the baseline is defined as the latent heat quantity (Q), and the latent heat quantity (Q) is divided by the weight of the accurately measured measurement sample, and converted into a latent heat quantity per unit weight. Asked.

Example 1
[Preparation process of polymerizable monomer composition]
50 parts of methyl methacrylate which is a (meth) acrylic monofunctional polymerizable monomer as a monofunctional polymerizable monomer, and a (meth) acrylic crosslinkable polymerizable monomer as a crosslinkable polymerizable monomer 50 parts of ethylene glycol dimethacrylate as a body was stirred and mixed at room temperature (25 ° C.) and uniformly dispersed to prepare a polymerizable monomer composition.

[Suspension step for obtaining a suspension]
On the other hand, in a stirring vessel equipped with an inclined paddle blade, a dispersion stabilizer is added to a magnesium chloride aqueous solution in which 8.2 parts of magnesium chloride is dissolved in 215 parts of ion-exchanged water as an aqueous dispersion medium at room temperature (25 ° C.). As a dispersion stabilizer, 10 parts of magnesium hydroxide particles (manufactured by Kyowa Chemical Industry Co., Ltd., trade name: Kisuma 5Q-S, number average primary particle size: 1 μm) are gradually added with uniform stirring. A dispersion was prepared.

  Here, when the magnesium hydroxide particles are added to the magnesium chloride aqueous solution, the magnesium hydroxide particles are uniformly dispersed from the state in which the magnesium hydroxide particles are non-uniformly present in the aqueous solution (uniform dispersion). It was 5 minutes when the time required for this state change was measured by visual observation until it changed to (state).

  The magnesium hydroxide particles were maintained in the aqueous dispersion medium with the same particle size, and the number average primary diameter was 1 μm.

  The above-mentioned polymerizable monomer composition is put into a dispersion of the dispersion stabilizer prepared as described above at room temperature (25 ° C.) and stirred until the droplets are stabilized. Add 3 parts of t-butyl peroxy-2-ethylhexanoate (trade name: Perbutyl O, manufactured by NOF Corporation), and use an in-line type emulsifier / disperser (trade name: Ebara Milder MDN303V, manufactured by Ebara Seisakusho). Then, a high-shear stirring was performed for 30 minutes at a rotational speed of 15,000 rpm, droplets of the polymerizable monomer composition were formed, and a suspension in which the droplets of the polymerizable monomer composition were dispersed (polymerizability) Monomer composition dispersion) was obtained.

[Suspension polymerization process]
The suspension (polymerizable monomer composition dispersion) obtained as described above was transferred into a polymerization reactor equipped with an inclined paddle blade, and the temperature was started to rise while maintaining the temperature at 90 ° C. The polymerization reaction was continued for 4 hours, and then the polymerization reactor was cooled to room temperature to obtain an aqueous dispersion of polymer particles.

[Washing process and drying process]
The aqueous dispersion of polymer particles obtained as described above was added dropwise with stirring at room temperature (25 ° C.) until the pH reached 6 to stabilize the dispersion remaining in the aqueous dispersion of polymer particles. The acid was washed with acid to remove it.

  Next, filtration separation is performed, and 500 parts of ion-exchanged water is newly added to the obtained solid content to reslurry, and water washing treatment (washing, filtration, dehydration) is repeated several times, and the obtained solid content Was put into a container of a vacuum dryer and vacuum-dried at 40 ° C. for 8 hours to produce polymer particles of Example 1 and used for the test.

  The surface shape of the polymer particles obtained in Example 1 was observed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., trade name: S-4700), and the SEM photograph is shown in FIG. It was.

(Example 2)
In the preparation process of the polymerizable monomer composition of Example 1, 50 parts of methyl methacrylate which is a (meth) acrylic monofunctional polymerizable monomer as a monofunctional polymerizable monomer, and a crosslinkable polymerizable property 50 parts of ethylene glycol dimethacrylate, a (meth) acrylic crosslinkable polymerizable monomer as a monomer, is stirred and mixed while being kept at 50 ° C., and uniformly dispersed, and then polyfunctional as a heat storage material A fatty acid ester compound, dipentaerythritol hexamyristate (number average molecular weight Mn = 1,840, melting point Tm: 64 ° C.), 10 parts, is added, stirred, mixed and dissolved to prepare a polymerizable monomer composition. Except that, polymer particles of Example 2 (microcapsule particles for heat storage material) were produced in the same manner as in Example 1 and used for the test.

  In addition, in the step of preparing the dispersion of the dispersion stabilizer of Example 2, when the magnesium hydroxide particles were added to the magnesium chloride aqueous solution, the magnesium hydroxide particles were present in a non-uniform manner in the aqueous solution. It was 5 minutes when the time required for this state change was measured by visually observing until it changed from the non-uniform state to a uniformly dispersed state (uniformly dispersed state).

Further, the magnesium hydroxide particles in the aqueous dispersion medium maintained the size of the particle diameter as it was, and the number average primary diameter was 1 μm.
Furthermore, the amount of latent heat of the polymer particles (microcapsule particles for heat storage material) produced in Example 2 was measured and found to be 26 J / g.

(Example 3)
In the step of preparing the dispersion of the dispersion stabilizer of Example 1, 215 parts of ion-exchanged water, which is an aqueous dispersion medium, at room temperature (25 ° C.) in a stirring tank equipped with the same inclined paddle blade as in Example 1. Without adding magnesium chloride, 7 parts of magnesium hydroxide particles (manufactured by Kyowa Chemical Industry Co., Ltd., trade name: Kisuma 5Q-S, number average primary particle size: 1 μm) are gradually added with stirring as a dispersion stabilizer. The polymer particles of Example 3 were produced in the same manner as in Example 1 except that the dispersion stabilizer was prepared by uniformly dispersing under the same conditions as in Example 1, and the test was conducted. Provided.

In addition, in the preparation process of the dispersion liquid of the dispersion stabilizer of Example 3, when the magnesium hydroxide particles were added to the ion-exchanged water as the aqueous dispersion medium, the magnesium hydroxide particles were not uniform in the aqueous dispersion medium. It was 30 minutes when the time required for this state change was measured by visually observing until it changed from the existing state to the uniformly dispersed state (uniformly dispersed state) after leaving the non-uniform state. .
Further, the magnesium hydroxide particles in the aqueous dispersion medium maintained the size of the particle diameter as it was, and the number average primary diameter was 1 μm.

Example 4
In the step of preparing the dispersion of the dispersion stabilizer of Example 1, 215 parts of ion-exchanged water, which is an aqueous dispersion medium, at room temperature (25 ° C.) in a stirring tank equipped with the same inclined paddle blade as in Example 1. Without adding magnesium chloride, 10 parts of magnesium hydroxide particles (manufactured by Uji Materials Co., Ltd., trade name: UD653, number average primary particle size: 3.1 μm) as a dispersion stabilizer are gradually added with stirring. The polymer particles of Example 4 were produced in the same manner as in Example 1 except that a dispersion of a dispersion stabilizer was prepared by uniformly dispersing under the same conditions as in Example 1 and subjected to the test. .

In addition, in the preparation process of the dispersion liquid of the dispersion stabilizer of Example 4, when the magnesium hydroxide particles were added to the ion-exchanged water as the aqueous dispersion medium, the magnesium hydroxide particles were not uniform in the aqueous dispersion medium. It was 30 minutes when the time required for this state change was measured by visually observing until it changed from the existing state to the uniformly dispersed state (uniformly dispersed state) after leaving the non-uniform state. .
Moreover, the particle diameter of the magnesium hydroxide particles was maintained as it was in the aqueous dispersion medium, and the number average primary diameter was 3.1 μm.

  Further, the surface shape of the polymer particles obtained in Example 4 was observed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., trade name: S-4700), and the SEM photograph is shown in FIG. It was.

(Comparative Example 1)
In the step of preparing the dispersion of the dispersion stabilizer of Example 1, 215 parts of ion-exchanged water, which is an aqueous dispersion medium, at room temperature (25 ° C.) in a stirring tank equipped with the same inclined paddle blade as in Example 1. 10 parts of calcium carbonate particles (manufactured by Shiraishi Calcium Co., Ltd., trade name: Softon 2200, number average primary particle size: 1 μm) as a dispersion stabilizer are stirred in a magnesium chloride aqueous solution in which 8.2 parts of magnesium chloride is dissolved. The polymer particles of Comparative Example 1 were prepared in the same manner as in Example 1 except that the dispersion stabilizer was gradually dispersed under the same conditions as in Example 1 to prepare a dispersion of the dispersion stabilizer. Attempts were made to obtain only an agglomerated polymer.

In addition, in the preparation process of the dispersion of the dispersion stabilizer of Comparative Example 1, when the calcium carbonate particles are added to the ion-exchanged water that is the aqueous dispersion medium, the calcium carbonate particles are non-uniformly present in the aqueous dispersion medium. It was 20 minutes when the time required for the state change was measured by visually observing from the state where the state was removed to the state where the state was uniformly dispersed (uniformly dispersed state).
In addition, the calcium carbonate particles maintained their particle size as they were in the aqueous dispersion medium, and the number average primary diameter was 1 μm.

(Comparative Example 2)
In the step of preparing the dispersion liquid of the dispersion stabilizer of Example 1, 165 parts of ion-exchanged water, which is an aqueous dispersion medium, at room temperature (25 ° C.) in a stirring tank equipped with the same inclined paddle blade as that of Example 1. To a magnesium chloride aqueous solution in which 24.5 parts of magnesium chloride are dissolved in, an aqueous sodium hydroxide solution in which 13.7 parts of sodium hydroxide is dissolved in 50 parts of ion-exchanged water, which is an aqueous dispersion medium, is gradually added with stirring. The polymer particles of Comparative Example 2 were prepared in the same manner as in Example 1 except that a dispersion liquid of a dispersion stabilizer was prepared by uniformly dispersing under the same conditions as in Example 1. Provided.

  In the step of preparing the dispersion of the dispersion stabilizer of Comparative Example 2, a part of the produced magnesium hydroxide colloidal dispersion was collected, and the particle size distribution of the magnesium hydroxide colloid was measured using a particle size distribution measuring device ( When measured using a Shimadzu Corporation product name: SALD, the colloid particle size was D50 (50% cumulative value of the number particle size distribution) of 0.28 μm.

(Comparative Example 3)
In the step of preparing the dispersion liquid of the dispersion stabilizer of Example 1, 165 parts of ion-exchanged water, which is an aqueous dispersion medium, at room temperature (25 ° C.) in a stirring tank equipped with the same inclined paddle blade as that of Example 1. To a magnesium chloride aqueous solution in which 2.5 parts of magnesium chloride was dissolved in, an aqueous sodium hydroxide solution in which 1.4 parts of sodium hydroxide was dissolved in 50 parts of ion-exchanged water as an aqueous dispersion medium was gradually added with stirring. The polymer particles of Comparative Example 3 were prepared in the same manner as in Example 1 except that a dispersion liquid of a dispersion stabilizer was prepared by uniformly dispersing under the same conditions as in Example 1. Only a polymer in an agglomerated state was obtained.

  In the step of preparing the dispersion of the dispersion stabilizer of Comparative Example 3, a part of the produced magnesium hydroxide colloidal dispersion was collected, and the particle size distribution of the magnesium hydroxide colloid was measured using a particle size distribution measuring device ( When measured using a Shimadzu Corporation product name: SALD, the colloid particle size was D50 (50% cumulative value of the number particle size distribution) of 0.28 μm.

(result)
Table 1 shows the test results of the polymer particles prepared in each Example and Comparative Example.

(Summary of results)
From the test results described in Table 1, the following can be understood.
In the production method of Comparative Example 1, due to the use of the dispersion containing calcium carbonate particles as the dispersion stabilizer, droplets of the polymerizable monomer composition were formed in the suspension step of obtaining the suspension. It was not possible to carry out suitably, and only a polymer in an aggregated state was obtained.

  In the production method of Comparative Example 2, a polymerizable monomer composition was obtained in the suspension step of obtaining a suspension due to the use of a colloidal dispersion containing magnesium hydroxide having a small colloidal particle size as a dispersion stabilizer. Although droplets of the product could be dispersed uniformly, only polymer particles having a small particle size were obtained.

  In the production method of Comparative Example 3, a suspension is obtained by using a colloidal dispersion containing 1/10 of the amount of magnesium hydroxide having a small colloid particle size as compared with that of Comparative Example 2 as a dispersion stabilizer. In the process, droplet formation of the polymerizable monomer composition could not be suitably performed, and only an aggregated polymer was obtained.

  On the other hand, in the production methods of Examples 1 to 4, the polymerizable monomer composition originated from the preparation of the dispersion using magnesium hydroxide particles having a specific particle size range as the dispersion stabilizer. As a result of confirming the surface shape by SEM photography, polymer particles having a relatively large particle size desired in the present invention were obtained.

Claims (4)

A step of preparing a polymerizable monomer composition containing at least one or more polymerizable monomers, and suspending the polymerizable monomer composition in an aqueous dispersion medium containing a dispersion stabilizer; A suspension step for obtaining a suspension in which droplets of the polymerizable monomer composition are dispersed, and a step for obtaining polymer particles by subjecting the suspension to suspension polymerization in the presence of a polymerization initiator. A method for producing polymer particles comprising:
In the suspension step for obtaining the suspension, the dispersion stabilizer is magnesium hydroxide particles having a number average primary particle size of 0.5 to 10 μm.   In the step of preparing the polymerizable monomer composition, the polymerizable monomer composition contains a wax having a melting point of 5 to 150 ° C. as a heat storage material, and the content of the wax is a polymerizable monomer. The method for producing polymer particles according to claim 1, wherein the amount is 5 to 200 parts by weight with respect to 100 parts by weight.   The polymerizable monomer in the polymerizable monomer composition contains a crosslinkable polymerizable monomer, and the component ratio of the crosslinkable polymerizable monomer is 10 of the total amount of polymerizable monomers. The method for producing polymer particles according to claim 2, wherein the polymer particle content is at least wt%.   The method for producing polymer particles according to any one of claims 1 to 3, wherein in the suspension step of obtaining the suspension, the aqueous dispersion medium contains magnesium chloride.