JPH0651728B2 - Method for producing polymer particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing monodisperse polymer particles having a relatively large diameter and having a particle diameter in the range of about 1 to 100 µm.

[Conventional technology]

Although monodisperse polymer particles having a particle size in the range of about 1 to 100 μm are in demand in many fields,
It is generally extremely difficult to manufacture. In the production of polymer particles by emulsion polymerization, monodisperse polymer particles can be obtained relatively easily, but usually only particles having a small particle size of 1 μm or less can be obtained, and even under special conditions, 3 μm can be obtained. It is said to be the limit. On the other hand, in the production of polymer particles by suspension polymerization, it is possible to obtain relatively large-sized polymer particles having a particle size of 1 to 100 μm, but the particle size distribution is wide and monodisperse polymer particles are produced. Is extremely difficult. Therefore, in order to obtain monodisperse polymer particles, it is necessary to classify the particles obtained by suspension polymerization, and therefore the number of steps is large and the production is not easy, and It has a problem of low yield.

As a method for producing relatively large-diameter, monodisperse polymer particles, there are disclosed in JP-A-54-97582 or JP-A-54-126288.
The technique disclosed in Japanese Patent Publication is known.

In JP-A-54-97582, a chain transfer agent is added during emulsion polymerization to synthesize a polymer having a molecular weight much lower than that of ordinary polymer latex, and this is used as a seed particle. A method of absorbing and polymerizing an unsaturated monomer which is somewhat soluble in water is disclosed. However, in this method, when a commonly used oil-soluble initiator or water-soluble initiator is used, problems such as the generation of coagulation or the generation of new particles occur, and the monodisperse polymer particles having a large particle size are reliably collected. It is difficult to get it efficiently.

Further, in JP-A-54-126288, in the first step, the solubility in water that functions as a swelling aid is 10
^-Seed particles are allowed to absorb organic compounds smaller than ^-2 g / H ₂ O, and then, in the second step, monomers that are somewhat soluble in 100 times the volume of the seed particles are absorbed. After forming the swollen particles of the monomer, a water-soluble polymerization initiator such as potassium persulfate or an oil-soluble polymerization initiator such as azoisobutyronitrile (AIBN) was used as a polymerization initiator to maintain the particle shape. A method of polymerizing as-is is disclosed. However, in this method, when an oil-based polymerization initiator is used as the polymerization initiator, even the dispersed phase of the monomer that is not absorbed by the seed particles is polymerized as it is, so that a large amount of coagulated product is formed. There is a drawback that the yield is low. When a water-soluble polymerization initiator such as persulfate is used as the polymerization initiator, the growing radicals in the aqueous phase act as an emulsifier even when the emulsifier concentration is below the critical micelle concentration, so-called soap-free emulsification. There is a drawback that the polymerization proceeds partially or entirely and the morphology of swollen particles is not maintained. Furthermore, in this method, when the polymer particles to be obtained do not become spherical and become distorted due to the action of the low water-soluble organic compound as a swelling aid to be absorbed by the seed particles in the first step of the process. There are also points.

As a method for solving these problems, a method of enlarging seed particles without using a swelling aid is disclosed in J. Poly.
m.Sci., Polym. Lett. Ed., 21 , 937-943 (1983) (JHJan
sson, MC Wellons, GW Poehlein). According to this method, a monomer and an oil-soluble polymerization initiator are mixed, and this mixture is finely dispersed to prepare a monomer emulsion, which is added to a dispersion of seed particles (latex). It is thus possible to achieve enlargement of the seed particles with a high swelling ratio of 14: 1.

However, in this method, the above-mentioned JP-A-54-1268 is used.
Compared with the method using a swelling aid in JP-A-8, there is a big problem that the particle size uniformity of the obtained polymer particles is inferior even if the seed particles under the same conditions are used.

The non-uniformity of the particle size in such polymer particles is considered to be caused by the following phenomenon. That is, since the monomer mixture is mixed with the oil-soluble polymerization initiator and then the monomer mixture is dispersed in the aqueous dispersion medium, the monomer is heated by heat generated by the high shear energy applied to the system in the dispersion step. Part of it polymerizes, producing a small amount of polymer in the droplets of the monomer mixture. Then, since the surrounding monomer mixture is absorbed by the polymer and the droplets of the monomer mixture are stabilized, the droplets of the monomer mixture which are not absorbed by the seed particles and remain in the dispersion medium are formed. There will be a large amount. As a result, a large number of unnecessary polymer particles are generated by the polymerization treatment, and the range of the particle size distribution of the obtained polymer particles becomes large, resulting in polydispersion.

In the above, generation of unnecessary polymer particles in the dispersion step can be prevented by cooling the system to remove heat generated by shearing, but such heat is spread throughout the system. It is practically extremely difficult to sufficiently remove it, and it is difficult to completely eliminate the above-mentioned problems even by an advanced cooling equipment.

Further, in this method for producing polymer particles, there is a problem that the storage stability is extremely low because the monomer and the polymerization initiator are used in a mixed state.

[Problems to be solved by the invention]

The present invention has the following problems of the prior art, (a) it is not possible to obtain a polymer particle having a wide particle diameter distribution and a uniform particle diameter, (b) it is difficult to obtain a true polymer particle It is an object of the present invention to provide a method for producing polymer particles, which can solve the above problems, and can reliably produce true spherical polymer particles having high monodispersity by a simple process.

[Means for solving problems]

The above problems are caused by the aqueous dispersion of seed particles and the following 2
Seed aqueous dispersion, (a) an aqueous dispersion in which the polymerizable unsaturated monomer has a particle size smaller than the seed particles, and (b) an oil-soluble polymerization initiator particles smaller than the seed particles. Mixed with an aqueous dispersion dispersed in a state having a diameter,
This is solved by a method for producing polymer particles, characterized in that polymerization is carried out after absorbing or adsorbing the polymerizable unsaturated monomer and the oil-soluble polymerization initiator to the seed particles.

That is, in the present invention, the polymerizable unsaturated monomer and the oil-soluble polymerization initiator are previously dispersed in water in a state where the particle size of the dispersed particles (oil droplets) is smaller than the particle size of the seed particles. Each of the aqueous dispersion is prepared, and then these aqueous dispersion and an aqueous dispersion of seed particles are mixed to bring the polymerizable unsaturated monomer and the oil-soluble polymerization initiator into contact with the seed particles, to absorb them, It has a feature in that the polymerization is performed thereafter.

The present invention will be described in detail below.

The polymerizable unsaturated monomer that can be used in the present invention preferably has a solubility in water of 0.001 to 0.2% by weight. If the solubility of the monomer in water is too low,
Since the finely dispersed polymerizable unsaturated monomer has good stability, it takes an extremely long time for the monomer to be absorbed into the seed particles, which is not preferable. On the other hand, if the solubility of the monomer in water is too high, the oil droplets of the finely dispersed monomer are unstable, so that the life is significantly shortened, and the monomer is dispersed in a state smaller than the seed particles. Preparation of the aqueous dispersion becomes difficult.

Solubility in water is in the range of 0.001-0.2% by weight,
Examples of the polymerizable unsaturated monomer that can be preferably used in the present invention include styrene, α-methylstyrene and P-
Aromatic vinyl monomers such as methylstyrene and divinylbenzene, butyl acrylate, butyl methacrylate, 2
Examples thereof include ethylenically unsaturated carboxylic acid alkyl esters such as ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate and trimethylolpropane trimethacrylate, and conjugated diolephins such as butadiene and isoprene. These monomers can use 1 type (s) or 2 or more types.

When a weight-unsaturated monomer having a solubility in water of more than 0.2% by weight is used, it is extremely difficult to finely disperse this monomer into particles having a particle size of 1 μm or less. It is preferable to add 0.1 part by weight or more of the dispersion aid to 100 parts by weight of the unsaturated monomer.

As the above dispersion aid, the solubility in water is 0.001% by weight.
The following lipophilic substances may be used, and n-hexane, heptane, octane, 1-chlorodecane, dioctyl adipate, as well as polymerizable unsaturated monomers such as stearyl vinyl ether and stearyl methacrylate can be exemplified. .

As the polymerizable unsaturated monomer having a solubility in water of more than 0.2% by weight, vinyl acetate, acrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrylate, vinylidene chloride, ethyl methacrylate, ethylene glycol, diacrylate, ethylene glycol dimethacrylate, Acrylamide, methacrylamide,
Glycidyl acrylate, glycidyl methacrylate,
N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, 2-
Examples thereof include hydroxyethyl methacrylate, diallyl phthalate, allyl acrylate, allyl methacrylate, acrylic acid, methacrylic acid, itaconic acid and fumaric acid.

When a polymerizable unsaturated monomer with a solubility in water of less than 0.001% by weight is used, when it is finely dispersed in water and then absorbed or adsorbed by the seed particles, a water-soluble organic solvent is added to finely add it. It is preferable to promote the absorption or adsorption to the seed particles by destabilizing the dispersed droplets. Examples of the water-soluble organic solvent that can be used for this purpose include acetone, methanol, ethanol, dimethylformamide, and tetrahydrofuran.

Examples of the polymerizable unsaturated monomer having a solubility in water of less than 0.001% by weight include stearyl vinyl ether and stearyl methacrylate.

In the present invention, from the viewpoint of preventing the generation of new particles in the aqueous phase during the polymerization, at least a part of the polymerizable unsaturated monomer, a monomer having a high polymerization conversion rate, such as divinylbenzene, acrylonitrile or It is preferable to use vinyl chloride or the like.

When the polymerizable unsaturated monomer is a plurality of types, a plurality of monomers may be mixed and then finely dispersed to prepare an aqueous dispersion, or each of the monomers may be used alone. It may be finely dispersed to prepare an aqueous dispersion. When using an aqueous dispersion in which each monomer is finely dispersed alone, the aqueous dispersion of the monomer and the aqueous dispersion of the seed particles are mixed in the order of increasing solubility of the monomer in water, It is preferred to absorb or adsorb the monomer to the seed particles.

The seed particles that can be used in the present invention are preferably those that absorb a polymerizable unsaturated monomer and swell, a styrene copolymer such as a styrene polymer or a styrene-butadiene copolymer, an acrylic ester-based polymer. Examples thereof include polymers such as coalesced polymers and vinyl acetate polymers.
These seed particles are used in the state of dispersion such as aqueous latex and emulsion. Further, a polymer having a composition having no swelling property, a highly crosslinkable polymer, and an aqueous dispersion of an inorganic substance whose surface is subjected to lipophilic treatment can also be used.

The particle size of the seed particles is preferably uniform in order to make the particle size of the polymer particles finally obtained uniform. The particle size of the seed particles is appropriately selected depending on the intended use of the polymer particles to be obtained, but is usually 1 μm or less, preferably 0.2 to 0.9 μm. Further, the polymer particles obtained in the present invention can be used as seed particles in the next step to produce larger particles.

The oil-soluble polymerization initiator that can be used in the present invention preferably has a solubility in water in the range of 0.001 to 0.2% by weight. If the solubility of the oil-soluble polymerization initiator in water is too low, the stability of the finely-dispersed oil-soluble polymerization initiator is good, and this polymerization initiator takes remarkably long time to be absorbed into the seed particles. Absent. On the other hand, if the solubility of the oil-soluble polymerization initiator in water is excessive, the life of the oil droplets of the finely dispersed polymerization initiator is unstable and the life thereof is significantly shortened, and the polymerization initiator is finely dispersed smaller than the seed particles. It will be difficult to prepare the aqueous dispersion in this state.

Solubility in water is in the range of 0.001 to 0.2% by weight,
Examples of the oil-soluble polymerization initiator that can be preferably used in the present invention include organic compounds such as 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy 2 ethylhexanoate, and di-t-butyl peroxide. Examples thereof include azo compounds such as peroxides, azobisisobutyronitrile, and azobiscyclohexanecarbonitrile.

When the oil-soluble polymerization initiator is in a solid state such as powder, it is preferable to use it after dissolving it in an inert organic solvent such as toluene or cyclohexane.

When using an oil-soluble polymerization initiator having a solubility in water of more than 0.2% by weight, it is difficult to finely disperse them, and therefore a dispersion aid is used in an amount of 0.1 part by weight or more based on 100 parts by weight of the polymerization initiator. It is necessary to add. Such a dispersion aid has a water solubility of 0.001% by weight.
The following inert oil-soluble substances may be used, and n-hexane, heptane, octane, dioctyl 1-chlorodecane adipate, etc. can be used.

Examples of the oil-soluble initiator having a solubility in water of more than 0.2% by weight include t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-butylhydroperoxide, acetylperoxide. , Isobutyryl peroxide, etc. can be exemplified.

Next, the process of the manufacturing method of the present invention will be specifically described.

In the present invention, the polymerizable unsaturated monomer and the oil-soluble polymerization initiator are efficiently and surely absorbed or adsorbed on the seed particles, in order to suppress the generation of unnecessary new particles and enhance monodispersity, It is important to make these polymerizable unsaturated monomers and oil-soluble polymerization initiators into an aqueous dispersion before adding them to the reaction system, and to make the dispersed oil droplets smaller than the seed particles. Is.

When a seed particle absorbs a monomer, the particle size of the seed particle usually increases due to swelling, but after that, the monomer or the polymerization when the finely dispersed monomer or the polymerization initiator is further added. The initiator particle size is within the scope of the method of the invention provided it is smaller than the particle size of the seed particles after swelling. However, in that case, it takes a long time to absorb the monomer or the polymerization initiator into the seed particles.

In order to finely disperse the oil droplets of the polymerizable unsaturated monomer and the oil-soluble polymerization initiator, it is necessary to apply a high shearing force to the dispersion. For that purpose, for example, a manton which is sheared under high pressure. Means using a Gaurin homogenizer or means using ultrasonic waves can be employed. In these means, it is necessary to carry out a cooling operation in order to avoid heat generation due to shearing.

In addition, a surfactant is used in order to improve dispersibility in the preparation of the dispersion. As such a surfactant, a usual one can be used, and examples thereof include anionic emulsifiers such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dialkylsulfosuccinate, and a formalin condensate of naphthalenesulfonic acid. Further, it is also possible to use a nonionic surfactant such as polyoxyethylene nonylphenol ether, polyethylene glycol monostearate or sorbitan monostearate together.

The order of addition of the respective aqueous dispersions of the polymerizable unsaturated monomer and the oil-soluble polymerization initiator to the aqueous dispersion of seed particles is not particularly limited, and the polymerization initiator or the reverse thereof may be added after the monomer. May be added sequentially, or both may be added simultaneously. The addition of each aqueous dispersion may be continuous or intermittent.

For example, specifically, first, an aqueous dispersion of an oil-soluble polymerization initiator is added to an aqueous dispersion of seed particles, and the system is usually allowed to stand for 1 hour until oil droplets of the polymerization initiator are completely absorbed in the seed particles. Stirring gently over the above, and then adding the aqueous dispersion of the polymerizable unsaturated monomer, usually over 1 hour or more until the oil droplets of this monomer are completely absorbed in the seed particles. Stir gently.

In such an absorbing operation, it is possible to add a water-soluble organic solvent or a water-soluble salt in order to accelerate the absorption of the finely dispersed oil droplets into the seed particles. However, it should be noted that the seed particles may be destabilized and aggregated at this time, and the particle size distribution of the obtained polymer particles may be broadened.

By the above absorption operation, the finely dispersed oil droplets disappear and the absorption into the seed particles is completed, and then the temperature of the system is raised to carry out the polymerization. Polymerization temperature is usually 40 ~ 90 ℃, preferably 50 ~
80 ℃

At the time of polymerization, it is necessary to use a dispersion stabilizer in order to increase the stability of dispersed particles. As such a dispersion stabilizer, those usually used may be used, and an anionic or nonionic surfactant or an organic or inorganic suspension protective agent is used. As a preferred dispersion stabilizer, polyvinyl alcohol having a saponification degree of 75 to 55% and a polymerization degree of 500 to 3,000 can be used.

During the polymerization, particles may be generated and grow in the aqueous phase regardless of the seed particles depending on the monomer composition, and ferric chloride or sodium sulfite may be added to suppress the growth.
A water-soluble polymerization inhibitor such as hydroquinone can also be added.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited thereto. In the following description, "parts" and "%" represent parts by weight and% by weight, respectively.

Example 1 t-Butylperoxy 2-ethylhexanoate "Perbutyl 0" (manufactured by NOF CORPORATION), 2 parts of sodium lauryl sulfate, 0.15 parts of water, and 20 parts of water were ultrasonically stirred to emulsify to obtain 0 parts of perbutyl. The oil droplets were finely dispersed so that the particle diameter was 0.5 μm or less. This dispersion was added to 40 parts of monodisperse polystyrene latex (solid concentration 5%) having a particle size of 0.80 μm, and the system was gently stirred at a temperature of 30 ° C. for 12 hours,
Oil droplets of perbutyl 0 were absorbed into polystyrene particles that were seed particles.

Then a monomer mixture of 90 parts styrene and 10 parts divinylbenzene, 2.85 parts sodium lauryl sulfate and 342 water.
Part of the mixture is ultrasonically stirred to emulsify, and the monomer mixture of styrene and divinylbenzene is finely dispersed so that the oil droplet size is 0.5 μm or less, and the obtained dispersion is dispersed with the seed particles. It was added to the body. Then, the system was gently stirred at a temperature of 30 ° C. for 12 hours to absorb the monomer in the seed particles.

After that, polyvinyl alcohol "Gothenol GH20"
100 parts of a 10% aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added and the temperature was raised to 80 ° C. to initiate polymerization. Polymerization is 4
Almost completed in time. There was almost no generation of coagulated matter and no generation of new particles in the water phase. Observation of the obtained polymer particles with a scanning electron microscope revealed that the particles were almost spherical and had an extremely uniform particle size with an average particle size of 2.8 μm and a particle size deviation value of 5%. confirmed. FIG. 1 is an electron micrograph showing the polymer particles.

Comparative Example 1 2 parts of perbutyl O, 90 parts of styrene, 10 parts of divinylbenzene, 3 parts of sodium lauryl sulfate and 400 parts of water were ultrasonically emulsified and finely dispersed so that the particle size of oil droplets was 0.5 μm or less. This dispersion was added to 2 parts (solid content concentration) of monodisperse polystyrene latex having a particle size of 0.80 μm (concentration of solid content: 5%), and the mixture was stirred gently at a temperature of 30 ° C. for 24 hours to allow monodispersion in seed particles. The oil droplets of the polymer and the polymerization initiator were absorbed, but the oil droplets did not disappear, and the oil droplets did not disappear even after stirring for 48 hours. Then, 100 parts of a 10% aqueous solution of polyvinyl alcohol was added, the temperature of the system was raised to 80 ° C., and the reaction was carried out for 4 hours, whereby the polymerization was almost completed. When the obtained polymer particles were observed with a scanning electron microscope, the particles were a mixture of particles having a uniform particle size of about 2.7 μm and particles having a nonuniform particle size of 0.5 to 2 μm. . FIG. 2 is a photomicrograph showing the polymer particles.

Example 2 20 parts of 3,5,5-trimethylhexanoyl peroxide "Perloyl 355" (manufactured by NOF CORPORATION), 0.5 part of sodium lauryl sulfate and 100 parts of water were emulsified using ultrasonic waves, and the particle size of oil droplets was obtained. Of 0.6 μm or less was finely dispersed. This dispersion was added to 50 parts of an aqueous dispersion of polystyrene having a particle size of 0.9 μm (solid content concentration 2%),
The seed particles, polystyrene, were allowed to absorb the perloyl 355 while being gently stirred at 24 ° C. for 24 hours.
300 parts of styrene, 3.75 parts of sodium lauryl sulphate and 500 parts of water are finely dispersed using a Manton Gaulin homogenizer so that the particle size of oil droplets is 0.8 μm or less, and this dispersion is dispersed in the dispersion of the seed particles. Add 1 at 30 ° C
The styrene was further absorbed in the seed particles by gently stirring for 0 hours.

Next, 300 parts of butyl acrylate, 3.75 parts of sodium lauryl sulphate and 500 parts of water were finely dispersed using a Manton Gaulin homogenizer so that the particle size of the oil droplets would be 0.8 μm or less, and this dispersion was used as a dispersion of seed particles. It was further added into the mixture, and the mixture was stirred gently at 30 ° C. for 5 hours to absorb butyl acrylate in the seed particles.

Then, 400 parts of acrylonitrile, 7.5 parts of sodium lauryl sulfate, 1000 parts of water and 40 parts of n-hexane are emulsified and finely dispersed by a Manton Gaulin homogenizer to make the particle size of oil droplets 0.5 μm or less. Then, the mixture was gently stirred at 30 ° C. for 42 hours to absorb acrylonitrile in the seed particles.

The size of the swollen seed particles having a uniform particle size thus obtained was about 9 μm. 1000 parts of a 10% aqueous solution of polyvinyl alcohol was added to this dispersion, and the temperature was raised to 70 ° C. for polymerization. The polymerization was almost complete in 6 hours. When the obtained polymer particles were observed with an optical microscope, it was confirmed that the polymer particles were substantially spherical particles having an average particle size of 8.6 μm and a standard deviation of 7%.

Example 3 30 parts of t-butyl peroxy 2-ethylhexanoate "Perbutyl O" (manufactured by NOF CORPORATION), 2 parts of sodium lauryl sulfate and 150 parts of water were used to obtain oil particles having a particle size of 0.5 using a Manton Gaulin homogenizer. Finely dispersed so as to have a particle size of not more than μm. This dispersion was immediately added to 50 parts of monodisperse polystyrene latex (solid content: 2%) having a particle size of 0.83 μm, and the mixture was gently stirred at 20 ° C. for 24 hours to absorb oil droplets of perbutyl O into seed particles. Let

Next, 700 parts of styrene, 8 parts of sodium lauryl sulfate and 1000 parts of water were finely dispersed by a Manton Gaulin homogenizer so that the particle size of oil droplets was 0.5 μm or less. This dispersion was added to the above dispersion of seed particles in two portions and stirred for 12 hours each to absorb oil droplets of styrene into the seed particles.

Next, 800 parts of acrylonitrile and 20 parts of 1-chlorododecane
Part mixture, 10 parts sodium lauryl sulfate and 20 parts water
00 parts were finely dispersed with a Manton Gaulin homogenizer, and while confirming that the oil droplets were finely dispersed to a particle size of 0.7 μm or less, this was divided into four equal parts and added to the above dispersion of seed particles. Absorption operation was performed 4 times over 12 hours. After observing with an optical microscope after this absorption operation, it was found that the oil droplets composed of the dispersed swollen seed particles had a uniform particle diameter of about 9 μm.

To this dispersion, polyvinyl alcohol "Gothenol GH
20 "(manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10% aqueous solution 1500
Parts and 5 parts of a 10% aqueous solution of ferric chloride are added, and the mixture is heated to 80 ° C.
And reacted for 10 hours. The obtained polymer particles were spherical particles having an average particle size of 9.2 μm and a uniform particle size with a standard deviation of 3%.

Example 4 20 parts of magnetite "EPT500" (manufactured by Toda Kogyo Co., Ltd.)
Disperse in 60 parts of 0.005 mol / ferric chloride aqueous solution,
A positive charge was applied to the surface of the magnetite particles. Next, a 40% aqueous solution of sodium oleate 40% was added to this dispersion.
After adding oleic acid partly to adsorb oleic acid, dilute hydrochloric acid
The excess oleic acid was removed to 7 to obtain a lipophilic magnetite. Using 20 parts of this magnetite as seed particles, this was dispersed in 200 parts of a 5% aqueous solution of polyvinyl alcohol "Gothenol GH20" to obtain a dispersion of seed particles having a particle size of 0.3 to 0.5 µm.

To this dispersion, 80 parts of styrene, 200 parts of water and 1.5 parts of sodium lauryl sulfate were emulsified and dispersed by a Manton Gaulin homogenizer until the droplets of styrene became 0.1 μm or less, and the mixture was allowed to stand for 18 hours. Slowly and stirred to adsorb styrene on the surface of magnetite.

Further to this dispersion, azobisisobutyronitrile 1
Parts, 10 parts of toluene, 50 parts of water, and 0.3 parts of sodium lauryl sulfate were emulsified and dispersed so that the particle diameter of the droplets was 0.1 μm or less, and the droplets were adsorbed on the surface of magnetite.

This was polymerized at 70 ° C. for 10 hours to obtain magnetite-containing polymer particles having a particle size range of 2 to 7 μm and a magnetic substance content of 23%.

Comparative Example 2 2 parts of perbutyl O, 0.15 part of sodium lauryl sulfate, and 20 parts of water were emulsified with a homomixer and finely dispersed so that the particle size of oil droplets of perbutyl O was in the range of 0.8 to 5 μm. 90 parts of styrene, 10 parts of divinylbenzene
Part, 2.85 parts of sodium lauryl sulfate and 342 parts of water are emulsified with a homomixer to obtain oil droplets having a particle size of 0.8 to 5 μm.
Finely dispersed so as to fall within the range.

The above dispersion was added to 2 parts (in terms of solid content) of monodisperse polystyrene latex (solid content concentration 5%) having a particle diameter of 0.80 μm, and the mixture was gently stirred at a temperature of 30 ° C. for 72 hours to be absorbed. Then a 10% aqueous solution of polyvinyl alcohol
100 parts was added, the system was heated to 80 ° C., and the reaction was carried out for 4 hours.

When the obtained polymer particles were observed with an optical microscope, it was found that the particles were particles dispersed in a wide range of particle diameters of 1 to 50 μm.

(Effects of the Invention) According to the present invention, an oil-soluble polymerization initiator and a polymerizable unsaturated monomer are separately finely dispersed to prepare an aqueous dispersion, and these dispersions and seed particle dispersions are prepared. By mixing and agitating each of the polymerization initiator and the monomer to be absorbed by the seed particles, the polymerization due to the heat generated during the fine dispersion operation is avoided, and as a result, most of the monomers are surely contained in the seed particles. As a result, it is possible to prevent the production of unnecessary new particles, and thus it is possible to reliably produce polymer particles having good monodispersity.

Further, by using the lipophilicized inorganic substance as the seed particles, it is possible to obtain composite particles in which the surface of the seed particles is uniformly coated with the polymer.

The polymer particles produced in this way are excellent in monodispersibility without fine particles, and since the swelling aid is not used in the production, the polymer particles do not become distorted and are spherical. It has characteristics.

The polymer particles obtained by the production method of the present invention are used as standard materials for microscopic examination, separation, fluid flow, centrifugation, diffusivity measurement, model system materials such as dust research, and biomedical diagnostic agents. Carrier, immobilized enzyme carrier, powder ink, electrostatic development toner, paint, powder lubricant, microcapsule, spacer material for protecting microcapsule of pressure-sensitive copying paper, spacer for liquid crystal cell, plastic pigment for coated paper, adhesive Examples thereof include plastic pigments for agents, binders for ceramics, base polymer particles for impact resistant resins, plastic pigments for cosmetics, column packings for ion chromatography, and the like, which are extremely useful in various fields.

[Brief description of drawings]

1 and 2 are scanning electron micrographs showing the structures of polymer particles according to Examples and Comparative Examples.

Claims (5)

[Claims] 1. An aqueous dispersion of seed particles, and the following two aqueous dispersions: (a) An aqueous dispersion in which a polymerizable unsaturated monomer is dispersed in a state of having a particle size smaller than the seed particles. , And (b) an oil-soluble polymerization initiator, and an aqueous dispersion dispersed in a state of having a particle size smaller than the seed particles, and mixed,
A method for producing polymer particles, which comprises conducting polymerization after the polymerizable unsaturated monomer and the oil-soluble polymerization initiator are absorbed or adsorbed on the seed particles. 2. The polymerizable unsaturated monomer is contained in an amount of from 0.001 to water.
The method for producing polymer particles according to claim 1, which has a solubility of 0.2% by weight. 3. The oil-soluble polymerization initiator is 0.001 to 0.2 in water.
The method for producing polymer particles according to claim 1 or 2, which has a solubility of wt%. 4. The polymerizable unsaturated monomer is 0.2% by weight with respect to water.
The polymerizable unsaturated monomer 100 having a higher solubility
The method for producing polymer particles according to claim 1, wherein 0.1 part by weight or more of the highly lipophilic substance having a water solubility of 0.001% by weight or less is added to the weight part. 5. A highly lipophilic substance in which the oil-soluble polymerization initiator has a solubility in water of more than 0.2% by weight, and the solubility in water is 0.001% by weight or less with respect to 100 parts by weight of the oil-soluble polymerization initiator. Claim 1 in which 0.1 part by weight or more is added
Item 5. The method for producing polymer particles according to Item 4.