JP2001261313A - Method of producing amorphous calcium phosphate slurry and method of producing polymeric particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing amorphous calcium phosphate slurry capable of being kept in a highly dispersed state for a long period, and to provide a method of producing fine polymeric particles having uniform particle diameters by using the slurry. SOLUTION: This method of producing amorphous calcium phosphate slurry comprises adding a calcium component to water, pulverizing and dispersing by subjecting the mixture to a through shearing treatment to make slurry, and further adding a highly concentrated aqueous phosphoric acid solution containing 25-85 wt.% of a phosphoric acid component to the obtained slurry to form the amorphous calcium phosphate particles. The method of producing the polymeric particles comprises using the above amorphous calcium phosphate slurry as a dispersion stabilizer when an ethylenic monomer is subjected to water-based suspension polymerization in the presence of a polymerization initiator and a surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an amorphous calcium phosphate slurry having excellent dispersion stability, and a method of using this slurry as a dispersion stabilizer to obtain a fine and fine particle having a particle diameter distributed in a desired narrow range. The present invention relates to a method for producing polymer particles.

[0002]

2. Description of the Related Art Amorphous calcium phosphate is a substance widely distributed in nature in the form of phosphate rock or animal bone.
This amorphous calcium phosphate is applied to artificial bone materials, tooth repair materials, and the like, or uses ion exchange materials, pigments, cosmetics,
It is applied to UV inhibitors. Fine particles of amorphous calcium phosphate are used as a stabilizer to maintain the suspension of monomers and polymers in an aqueous medium during the production of a polymer by the suspension polymerization method, and as an anti-blocking agent during the production of a plastic film. It is also used as an agent.

[0003] However, amorphous calcium phosphate is usually aggregated by van der Waals force, ionic charge, etc., despite the fact that the primary particles produced during its production are fine particles of 0.1 μm or less. And an aggregate having a particle size of about 4 to 100 μm, and the dispersibility is reduced.

[0004] As a method of forming amorphous calcium phosphate into fine particles, for example, Japanese Patent Application Laid-Open No. 9-142817 discloses a slurry obtained by synthesizing hydroxyapatite.
A method is disclosed in which a strong shearing treatment is performed using a bead mill and the sedimentation half-life is extended by about 5 to 25 minutes by re-dispersion. JP-A-9-301708 discloses that once apatite is synthesized, the obtained apatite particles are redispersed in an organic solvent compatible with water, and the resulting apatite slurry is supplied to a stirring mill. A method is disclosed in which pulverization and dispersion treatment are performed until substantially no particles having a particle diameter of 3 μm or more are present.

Amorphous calcium phosphate having a particle size of about submicron or several microns, specifically, an average particle size of about 0.1 to 4 μm, such as the above-mentioned stabilizer for suspension polymerization or an antiblocking agent, is used. In the required field, there is a problem that a step of breaking up the generated aggregates is required, which takes time. In addition, in the technology disclosed in the above publication,
To make uniform, finely divided polymers with unequal sizes of suspended particles and thus a narrow particle size distribution,
It was not enough.

[0006] In order to solve these problems, the present inventors have added a calcium component to water, subjected to a whole shearing treatment, and pulverized and dispersed to produce a slurry. A method for producing an amorphous calcium phosphate slurry by adding a phosphoric acid aqueous solution while performing the treatment has been proposed (Japanese Patent Application Laid-Open No. H11-292524).

According to the production method described in this publication, an amorphous calcium phosphate slurry that can be easily dispersed in water and an organic solvent and that can maintain a state of being highly dispersed in water and an organic solvent for a long period of time can be efficiently produced. Obtainable. However, in the manufacturing method, since the synthesis is performed while performing the shearing treatment throughout, the heat generation in the synthesis system increases. Therefore, it was necessary to cool the reaction vessel during the synthesis and adjust the temperature to 20 to 60 ° C. In addition, due to this heat generation, a low-concentration aqueous solution of phosphoric acid had to be used, and the synthesis had to be carried out over a long period of time.

[0008]

SUMMARY OF THE INVENTION The inventors of the present invention
In the course of studying a method for producing an amorphous calcium phosphate slurry more easily and in a shorter time, an unexpected fact was discovered. In other words, the inventors of the present invention, when reacting the calcium component and the phosphoric acid component, instead of performing a full-shear treatment, if both components are reacted under mild stirring conditions, a high concentration of phosphoric acid Even when an aqueous solution is used, an amorphous calcium phosphate slurry having excellent dispersion stability can be obtained without surprising heat generation. The inventors have found that coalesced particles can be obtained, and have completed the present invention.

According to the present invention, an amorphous calcium phosphate slurry is produced efficiently and inexpensively, and by using this amorphous calcium phosphate slurry as a dispersion stabilizer, the size of the particles can be distributed in a desired narrow range. An object of the present invention is to provide a method for producing uniform polymer particles.

[0010]

According to the present invention, a slurry is produced by adding a calcium component to water, subjecting it to a full shearing treatment, and pulverizing and dispersing the slurry. A method for producing an amorphous calcium phosphate slurry, characterized in that amorphous calcium phosphate particles are produced by adding a high-concentration aqueous phosphoric acid solution (abbreviated as “%”).

Further, according to the present invention, when an ethylene-based monomer is subjected to aqueous suspension polymerization in the presence of a polymerization initiator and a surfactant, the amorphous calcium phosphate slurry obtained by the above method is dispersed. There is provided a method for producing polymer fine particles, which is used as a stabilizer. In the present invention, the “all-through shearing treatment” means that the operation of applying pressure to the slurry to pulverize and disperse the solid content in the medium is performed while the slurry is passed through a medium stirring mill.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the method of the present invention, a calcium component is added to water, subjected to a full shearing treatment, pulverized and dispersed to produce a slurry, and a phosphoric acid component is added to the slurry.
By adding a high-concentration phosphoric acid aqueous solution containing 5 to 85%, an amorphous calcium phosphate slurry is obtained.

The calcium component used in the method of the present invention is not particularly restricted but includes, for example, calcium hydroxide, calcium carbonate, calcium hydrogen phosphate and the like. The concentration of the calcium component is not particularly limited, but is usually about 0.01 to 80%, preferably 1 to 80%.
It is about 0 to 50%. The concentration of the calcium component is 0.0
If it is less than 1%, the production efficiency of the amorphous calcium phosphate particles is undesirably reduced. Conversely, if the concentration of the calcium component exceeds 80%, the calcium component may not be sufficiently pulverized, and the generated amorphous calcium phosphate particles may be easily aggregated by interaction, which is not preferable.

[0014] In the method of the present invention, the whole shearing treatment includes:
This is performed by supplying water containing a calcium component to a medium stirring mill. Examples of the medium-stirring mill include a flow-tube mill such as a disper mill, a homogenizer, a stirring mill, a sand grinder, and a pearl mill; , A stirred tank type mill, an annular type mill and the like. Among these devices, in that they can be manufactured continuously, more specifically, an all-purpose disper mill,
Mighty Mill (registered trademark, manufactured by Inoue Seisakusho), Dyno Mill (registered trademark, manufactured by Shinmaru Enterprises), S
A C mill (manufactured by Mitsui Mining Co., Ltd.), a high-pressure homogenizer and the like are preferably used.

The time of the whole shearing treatment is not particularly limited, but is usually about 10 to 240 minutes, preferably 1 to 240 minutes.
It is about 0 to 120 minutes. The conditions of the entire shearing treatment are appropriately set depending on the equipment used. For example, when a high-pressure homogenizer is used for the whole-pass shearing treatment, the pressure is usually set to about 300 to 500 kg / cm ² , and the outflow speed of the slurry is set to about 250 to 450 kg / hour.

When a mighty mill or SC mill is used, for example, the amount of sand mill beads is usually 30 to 60% of the volume of the vessel, the convection time is 5 to 10 minutes, and
The discharge amount is set to 3 to 10 kg / hour, respectively. By performing the whole shearing treatment, the calcium component in the water is pulverized and dispersed to form a slurry. A high-concentration aqueous solution of phosphoric acid containing 25 to 85% of a phosphoric acid component is added to this slurry with stirring to form amorphous calcium phosphate particles.

Examples of the phosphoric acid component include phosphoric acid, phosphate esters such as tricresyl phosphate, triphenyl phosphate and tributyl phosphate, or ammonium phosphate, potassium phosphate, calcium phosphate, disodium hydrogen phosphate, phosphorus phosphate, and the like. Salts such as iron acid, sodium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate and calcium hydrogen phosphate can also be used. These phosphoric acid components are appropriately selected depending on the type of the calcium component used. For example, when using calcium hydroxide as the calcium component, it is preferable to use phosphoric acid as the phosphoric acid component, and when using calcium carbonate or calcium hydrogen phosphate as the calcium component, use sodium phosphate as the phosphoric acid component Is preferred.

The amorphous calcium phosphate obtained by the method of the present invention has a main component represented by the formula: Ca ₃ (PO ₄ ) ₂ .nH ₂ O, and a part of the calcium is, for example, barium. , Strontium, zinc, magnesium, sodium, potassium, iron, aluminum, titanium, etc., and a part of PO ₄ is, for example, VO
₄ , it may be substituted with an atomic group such as SiO ₄ and CO ₃ . In addition, the amorphous calcium phosphate particles of the present invention have C
The weight ratio (Ca / P ratio) of a to P is 1.50 to 1.7.
5, and the primary particles may be in the form of needles, columns, plates, rice grains or oval.

The amorphous calcium phosphate particles obtained by the method of the present invention have an average particle size of 4 μm or less,
Substantially does not contain particles of 5 μm or more. The average particle diameter can be adjusted to 0.1 to 4 μm by adding water or an organic solvent compatible with water and further dispersing the mixture with a stirring mill or the like.

In the amorphous calcium phosphate slurry thus obtained, most of the calcium phosphate is in the form of primary particles, and almost no secondary particles constituting coarse particles of 4 μm or more are contained. Further, even when the whole shear dispersion is performed by a stirring mill, the pH caused by the unreacted aggregate does not increase, the pH is maintained in the range of 8 to 11, and the highly dispersed state is stably maintained. Can be maintained.

The amount of the amorphous calcium phosphate particles in water as a dispersion medium or in an organic solvent compatible with water, that is, the solid content concentration in the amorphous calcium phosphate slurry is different depending on the use and is particularly limited. Not something. However, if the solid content in the slurry is too low, the dispersion effect may be insufficient. On the other hand, if the solid concentration in the slurry is too high, the viscosity of the slurry becomes high, and reaggregation due to interaction of particles may occur. Therefore, when the dispersion medium is water, the solid content concentration in the amorphous calcium phosphate slurry is preferably 0.01 to 50% by weight, and more preferably 10 to 20% by weight.

The amorphous calcium phosphate slurry obtained by the method of the present invention may be, for example, a raw material for polyester fiber, a raw material for polyurethane, an adhesive, an ink, a brake oil, a raw material for polyethylene terephthalate (PET) resin, an antifreeze, a pharmaceutical or cosmetic product. Used as raw material, paste for electrolytic capacitors, and raw material for alkyd resin.

When the amorphous calcium phosphate slurry of the present invention is used as a raw material for polyester or the like, it can be used as it is, but it can also be used as a powder after removing the solvent. Further, antibacterial properties can be imparted to the obtained porous particles by adding and adsorbing antibacterial metal ions to the amorphous calcium phosphate slurry of the present invention.

Examples of such antibacterial metal ions include gold, silver, zinc, copper, tin, lead, arsenic, platinum, iron, antimony, nickel, aluminum, barium, cadmium, and manganese. These antibacterial metal ions may be used alone or in a mixture of two or more, a metal compound, or an aqueous solution thereof. Further, according to the present invention, the ethylene monomer,
In the presence of a polymerization initiator and a surfactant, when performing aqueous suspension polymerization, by using the amorphous calcium phosphate slurry as a dispersion stabilizer, a method for producing fine polymer particles having a uniform particle size is also available. Provided.

The ethylene monomer is not particularly restricted but includes, for example, styrene, p-methylstyrene and p-methylstyrene.
Styrene monomers such as chlorostyrene; acrylate monomers such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; methacrylate esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate Monomers; alkyl vinyl ether monomers such as polyethylene glycol mono (meth) acrylate and methyl vinyl ether; vinyl ester monomers such as vinyl acetate and vinyl butyrate; N-methyl amides such as N-methylacrylamide and N-ethylacrylamide Alkyl-substituted acrylamide monomer; acrylonitrile, (meth)
Examples include nitrile monomers such as acrylonitrile; and polyfunctional monomers such as divinylbenzene, ethylene glycol (meth) acrylate, and trimethylolpropane triacrylate. These monomers can be used alone or in combination of two or more.

The polymerization initiator is not particularly limited as long as it is a commonly used oil-soluble polymerization catalyst. For example, peroxide catalysts such as benzoyl peroxide, lauroyl peroxide, t-butyl peroxyoctoate, and azobisisopropane Azo catalysts such as butyronitrile and azobisisovaleronitrile are exemplified. The amount of the polymerization initiator used is about 0.001 to 10 parts by weight, based on 100 parts by weight of the ethylene monomer,
Preferably it is about 0.01 to 8 parts by weight.

The surfactant is not particularly restricted but includes, for example, anionic surfactants such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene lauryl ether sulfate and sodium dioctylsulfosuccinate. The surfactant is used in an amount of about 0.001 to 1 part by weight, preferably 0.002 part by weight, per 100 parts by weight of the ethylene monomer.
About 0.5 part by weight.

The amount of the amorphous calcium phosphate slurry added during the suspension polymerization depends on the amount of the aqueous dispersion medium of the suspension polymerization reaction.
The amount is about 0.01 to 30 parts by weight, preferably about 1 to 20 parts by weight, based on 0 parts by weight. As the aqueous dispersion medium,
Examples of the solvent include water alone or a mixed solvent mainly composed of water and having no compatibility with the oil phase. Water is most preferred. When the above-mentioned amorphous calcium phosphate slurry is used as a dispersion stabilizer, fine polymer fine particles having a narrow particle size distribution can be obtained, which were difficult to obtain by conventional suspension polymerization.

In order to suspend the ethylene monomer in the aqueous dispersion medium prior to the polymerization reaction, a high-speed rotary stirrer such as a batch processing type homomixer is generally used.
When suspended in a batch processing type homomixer, the liquid cannot be sheared, and the size of the resulting polymer particles tends to be non-uniform. Therefore, in order to obtain uniform polymer fine particles, it is preferable to use an in-line type homomixer such as a line mixer.

Further, Japanese Patent Application Laid-Open Nos. Hei 4-156555, Hei 6-110454 and Hei 10-152 are disclosed.
As shown in Japanese Patent Publication No. 506, a liquid under high pressure is caused to flow, and the liquid streams collide with each other, or collide with a predetermined flat portion, or a suspension is formed from fine pores. It is more preferable to use a device such as a nanomizer or a microfluidizer capable of jetting and crushing the suspended particles by the impact thereof to make the suspension particles finer, thereby producing a suspension of fine particles having a uniform size.

The polymer particles produced by the suspension polymerization of the present invention are separated from the aqueous dispersion medium by subjecting the reaction solution to filtration, centrifugation, etc., and then washed with water or a solvent and dried. , Can be obtained as a powder. In the suspension polymerization reaction of the present invention, various additives can be added to the reaction mixture depending on the use of the obtained resin particles. For example, when the polymer particles obtained by the method of the present invention are used as an electrophotographic toner, a colorant and a charge control agent are added to the reaction mixture.

Examples of the colorant include <black> carbon black and nigrosine dye (CI. No. 50415).
B), lamp black (CI No. 77266), oil black, azo oil black, <red> Dupont oil red (CI. No. 26105), rose bengal (CI. No. 45435), Orient Oil Red # 330 (CI No. 60505), <Yellow> Chrome Yellow (CI. No. 14090), Quinoline Yellow (CI. No. 47005), <Green> Malachite Green Oxalate ( C. I. No. 4200
0), <blue> Calco Oil Blue (CI No. az
oec blue 3), aniline blue (CI No. 50)
405), methylene blue chloride (CI No. 5)
2015), phthalocyanine blue (CI No. 74)
160), Ultramarine Blue (CI No. 771)
03). These colorants are used alone or in combination of two or more.

The amount of the colorant used is about 1 to 20 parts by weight based on 100 parts by weight of the ethylene monomer. The charge control agent is blended for controlling the triboelectric charging property of the toner, and there are two kinds of charge control agents, one for positive charge control and the other for negative charge control. Examples of charge control agents for controlling positive charges include basic dyes, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, organic compounds having a basic nitrogen atom such as aminosilanes, and fillers surface-treated with each of these compounds. And the like.

Examples of the charge control agent for controlling the negative charge include oil-soluble dyes such as nigrosine base (CI5045), oil black (CI26150), Bontron S, and spiron black; styrene-styrene sulfonic acid copolymer And the like; charge controlling resins such as alkyl salicylic acid metal chelates; metal complex salt dyes; fatty acid metal soaps; resin acid soaps; and metal naphthenates.

The use amount of these charge control agents is about 0.1 to 10 parts by weight, preferably about 0.5 to 8 parts by weight, based on 100 parts by weight of the ethylene monomer. Further, as other additives, an anti-offset agent for imparting an anti-offset effect to the toner, a magnetic substance powder, a crosslinking agent, and the like can be added.

Examples of the anti-offset agent include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids, fatty acid esters and partially saponified products thereof, silicone oils and various waxes. These may be used alone or Two or more types are used in combination. The amount of the offset preventing agent used is about 0.1 to 10 parts by weight, preferably about 0.5 to 8 parts by weight, based on 100 parts by weight of the ethylene monomer.

Among the above-mentioned offset inhibitors, aliphatic hydrocarbons having a weight average molecular weight of about 1,000 to 10,000 are preferred. Examples of the aliphatic hydrocarbon include low-molecular-weight polypropylene, low-molecular-weight polyethylene, paraffin wax, low-molecular-weight olefin polymer composed of olefin units having 4 or more carbon atoms, and silicone oil.

The material constituting the magnetic substance powder is preferably a substance which is strongly magnetized in that direction by a magnetic field and which is chemically stable.
Examples thereof include metals such as iron, nickel, aluminum, copper, magnesium, tin, zinc, antimony, beryllium, bismuth, calcium, selenium, titanium, tungsten, and vanadium, and compounds (oxides and the like), alloys, and mixtures thereof. The particle diameter of the magnetic powder is preferably 1 μm or less, more preferably about 0.01 to 1 μm.

The amount of the magnetic powder used varies depending on the use of the polymer particles. For example, when used in a magnetic carrier or a magnetic toner, about 20 to 300 parts by weight per 100 parts by weight of the ethylene monomer is used. Preferably 50 to 150
It is about parts by weight. Polymer particles obtained by adding a magnetic powder can be used as a magnetic carrier constituting a two-component developer together with an electrophotographic toner, or as magnetic particles used in a magnetic display or the like. When a magnetic powder is added to an electrophotographic toner, a magnetic toner as a one-component developer can be obtained.

[0040]

(Production of amorphous calcium phosphate slurry)

Example 1 500 g of calcium hydroxide was added to 9.5 liters of ion-exchanged water, and the mixture was supplied to an SC mill [manufactured by Mitsui Mining Co., Ltd.]. Then, 8000r
By circulating for 10 minutes under the conditions of pm and a treatment amount of 500 liters / hour, the whole shearing treatment was performed, and the calcium hydroxide was pulverized and dispersed. A 40% phosphoric acid aqueous solution was added to the slurry thus obtained by using a three-one motor manufactured by Haydon as a stirrer and rotating at 600 rpm.
The mixture was added over 1 hour while stirring under the condition of m. The reaction temperature was about 40 ° C., and an amorphous calcium phosphate slurry having a pH of 10 was obtained.

Comparative Example 1 200 g of calcium hydroxide was added to 9.0 liters of ion-exchanged water, and the mixture was supplied to an SC mill [manufactured by Mitsui Mining Co., Ltd.]. Then, 8000r
The slurry was subjected to a full shearing treatment for 10 minutes under the conditions of pm and a treatment amount of 500 liter / hour to obtain a slurry. To this slurry, a 5% phosphoric acid aqueous solution was added over a period of 90 minutes while performing the entire shearing treatment described above. However, the reaction temperature rose to 80 ° C. 5 minutes after the start of the dropping of phosphoric acid. An amorphous calcium phosphate slurry was produced by cooling with cooling water and forcibly air-cooling the reaction system so that the slurry temperature would be 60 ° C. or lower.

[Comparative Example 2] 500 g of calcium hydroxide was added to 9.5 liters of ion-exchanged water, and the calcium hydroxide was suspended by stirring at a rotation speed of 600 rpm using a three-one motor manufactured by Haydon as a stirrer. I let it. While stirring this suspension under the same conditions, an 8% aqueous phosphoric acid solution was added dropwise with stirring. The reaction temperature was 34 ° C and the pH was
Ten amorphous calcium phosphate slurries were obtained. Further, this slurry was pulverized with a bead mill for 5 minutes to obtain a slurry for a dispersant.

[Measurement of Average Particle Size of Amorphous Calcium Phosphate in Slurry] The particle size distribution of each slurry obtained in Example 1 and Comparative Examples 1 and 2 was measured by a sedimentation method. The particles obtained in Example 1 and Comparative Example 1 have an average particle size in the range of 0.1 to 4 μm and a particle size of 0.1 μm.
m or less than 4 μm. In contrast, many of the particles obtained in Comparative Example 2 had a particle size exceeding 4 μm, and the average particle size also exceeded 4 μm. In addition, it was confirmed that the aggregation of the amorphous calcium phosphate occurred with the increase in the pH.

[Measurement of Sedimentation Half-Life] In Example 1, Comparative Example 1 and Comparative Example 2, the slurry (dispersion liquid: water) immediately after the reaction of calcium hydroxide and phosphoric acid was used. Was measured by the following method. First, a well-dispersed amorphous calcium phosphate slurry was
1 Settler tube. This is then left at 25 ° C.
Measure the time until the volume of the precipitate reaches 50 ml,
This time was defined as the sedimentation half-life.

The settling half-lives of the slurries obtained in Example 1 and Comparative Example 1 were 190 minutes 10 seconds and 18 minutes, respectively.
The settling half-life of the slurry obtained in Comparative Example 2 was 40 minutes and 10 seconds, compared to 0 minutes and 30 seconds. Thus, the slurries obtained in Example 1 and Comparative Example 1 had a long sedimentation half-life, whereas the slurries obtained in Comparative Example 3 had a short sedimentation half-life.

[Measurement of Particle Size Distribution of Polymer Particles] The particle size distribution of the polymer particles obtained in Example 2 and Comparative Examples 2 and 3 described later was measured by a Coulter counter method. Regarding the results, the volume average particle diameter (Dw) and the number average particle diameter (Dn) of the particles were measured and evaluated using the respective standard deviations (σw and σn). Regarding the uniformity of the particle diameter, the value of Dw / Dn was close to 1, and it was evaluated that the smaller σw and σn, the more uniform the particle size distribution.

Example 2 475 g of methyl methacrylate in which 1.5 g of azobisisovaleronitrile was dissolved, 25 g of ethylene glycol dimethacrylate, 1.6 g of sodium lauryl sulfate (critical micelle concentration: 0.23%),
Amorphous calcium phosphate slurry 9 obtained in Example 1
An aqueous mixed solution containing 6 g (in terms of solid content) and 3200 g of water was treated with a TK homomixer MARKII 2.5 (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 16,000 rpm for 15 minutes to obtain a primary suspension having an average particle size of 5 μm A suspension was prepared. Next, using a Nanomizer LA-31 manufactured by Nanomizer, the primary suspension was passed once under a pressure of 1300 kg / cm ² to prepare a secondary suspension. This secondary suspension was charged into a polymerization reaction tank having an internal volume of 5 liters, and subjected to suspension polymerization for 8 hours under a gentle stirring at 50 ° C. and 300 rpm with an irrigating stirring blade to obtain polymer particles. .

When the volume distribution and the number distribution of the obtained polymer particles were examined using a Coulter counter manufactured by Coulter Co., Ltd., the volume average particle size (Dw) of the particles was 6.9 μm, and the standard deviation (σw) was obtained. ) Is 1.6μ
m, the number average particle diameter (Dn) was 5.7 μm, and the standard deviation (σn) was 1.6 μm. Thus, the resulting particles are localized in a narrow size distribution,
Particle size was uniform. FIG. 1 shows an electron micrograph of the obtained polymer particles, and FIG. 2 and FIG. 3 and Table 1 show the measurement results of the particle size distribution obtained by the Coulter counter.

Comparative Example 3 A polymerization reaction was carried out under the same conditions as in Example 2 except that the slurry obtained in Comparative Example 1 was used instead of the amorphous calcium phosphate slurry manufactured in Example 1. The measurement was performed on the obtained particles. The obtained polymer particles have a volume average particle diameter (Dw) of 6.8 μm, a standard deviation (σw) of 1.8 μm, a number average particle diameter (Dw) of 5.6 μm, and a standard deviation (σn). It was 1.5 μm. Thus, the obtained particles had a narrow particle size distribution and were uniform in particle size. An electron micrograph of the obtained polymer particles is shown in FIG.
5 and FIG. 6 and Table 1 show the measurement results of the particle size distribution obtained by the Coulter counter.

Comparative Example 4 A polymerization reaction was carried out under the same conditions as in Example 2 except that the slurry obtained in Comparative Example 2 was used instead of the amorphous calcium phosphate slurry obtained in Example 1. The obtained particles were measured. The obtained polymer particles have a volume average particle size (Dw) of 11.6.
μm, the standard deviation (σw) was 2.5 μm, but the number average particle diameter (Dn) was 7.5 μm, and the standard deviation (σw) was 2.5 μm.
n) was 3.94 μm, and there were many small particles. FIG. 7 shows an electron micrograph of the obtained polymer particles, and FIG. 8 shows the measurement results of the particle size distribution obtained with a Coulter counter.
9 and Table 1.

Table 1 Dw (μm) σw (μm) Dn (μm) σn (μm) Dw / Dn Example 2 6.9 1.6 5.7 1.6 1.21 Comparative Example 3 6.8 1. 8 5.6 1.5 1.21 Comparative Example 4 11.6 2.5 7.5 3.94 1.55

[0053]

According to the method of the present invention, an amorphous calcium phosphate slurry capable of maintaining a highly dispersed state in water for a long period of time can be obtained easily and efficiently. When suspension polymerization is performed using this amorphous calcium phosphate slurry as a dispersion stabilizer, fine polymer particles having a particle size distributed in a desired narrow range can be obtained.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of polymer particles obtained by the method of the present invention.

FIG. 2 is a graph showing a measurement result of a volume particle size distribution by a Coulter counter.

FIG. 3 is a graph showing a measurement result of a number particle size distribution by a Coulter counter.

FIG. 4 is an electron micrograph of a polymer particle obtained by a conventional method.

FIG. 5 is a graph showing a measurement result of a volume particle size distribution by a Coulter counter.

FIG. 6 is a graph showing measurement results of a number particle size distribution by a Coulter counter.

FIG. 7 is an electron micrograph of polymer particles obtained by a conventional method.

FIG. 8 is a graph showing a measurement result of a volume particle size distribution by a Coulter counter.

FIG. 9 is a graph showing the measurement result of the number particle size distribution by a Coulter counter.

Claims (2)

[Claims] 1. A calcium component is added to water, subjected to a whole shearing treatment and ground and dispersed to produce a slurry, and a high-concentration phosphoric acid aqueous solution containing 25 to 85% by weight of a phosphoric acid component is added to the slurry. And producing amorphous calcium phosphate particles. 2. The amorphous calcium phosphate slurry according to claim 1 is used as a dispersion stabilizer when an ethylene-based monomer is subjected to aqueous suspension polymerization in the presence of a polymerization initiator and a surfactant. A method for producing polymer particles.