JP2002105104A - Method for producing solid polymer particle or hollow polymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce solid polymer particles or hollow polymer particles having a desired particle diameter and high uniformity of the particle diameter in simple steps with good reproducibility. SOLUTION: The solid polymer particles are produced by the following steps (I) and (II). (I) the step of pressing (A) a uniform mixture liquid comprising 100 pts.wt. of a monomer component comprising 0.05-70 pts.wt. of a hydrophilic monomer, 0-20 pts.wt. of a cross-linking monomer and other monomers and 1-1,000 pts.wt. of an oily substance through a microporous membrane into (B) an immiscible liquid and producing an emulsion comprising a dispersed phase composed of the uniform mixture liquid (A) and a continuous phase composed of the liquid (B) and (II) the step of subjecting the resultant emulsion to polymerizing treatment of the monomer component and forming the solid polymer particles having an inner core part compose of the oily substance and a shell part composed of the polymer of the monomer component. The hollow particles are further produced by the following step (III). (III) the step of removing the oily substance in the solid polymer particles and forming the hollow polymer particles having the shell part composed of the polymer of the monomer component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing solid polymer particles and hollow polymer particles having a narrow particle size distribution in a simple process with good reproducibility. In the present specification, "solid polymer particles"
The term “hollow polymer particles” means particles having an outer shell made of a polymer (polymer) and an inner core made of an oily substance present inside the polymer. Particles having existing voids.

[0002]

2. Description of the Related Art Hollow polymer particles are known to be useful as organic fillers, light scattering materials, microcapsule particles having various substances incorporated therein, and the like. The method for producing the hollow polymer particles includes: (1) a method comprising granulating a polymer containing a foaming agent and then foaming the foaming agent; and (2) polymer particles containing a volatile substance such as butane inside. , Followed by gasification and expansion of volatile substances, (3) a method comprising melting a polymer and blowing a gas jet such as air onto this to enclose air bubbles, and (4) a method comprising: There is known a method comprising forming polymer particles containing an alkali-swellable substance, and then impregnating the polymer particles with an alkaline liquid to expand the alkali-swellable substance. However, in all of the above methods (1) to (4), it is difficult to control production conditions, and it is difficult to stably and reliably produce desired hollow particles. In particular, it is extremely difficult to stably produce hollow particles having a particle diameter of 5 μm or more and a uniform particle diameter.

In order to improve the above-mentioned disadvantages of the method for producing a hollow polymer, Japanese Patent Publication No. 5-40770 discloses a monomer component comprising a hydrophilic monomer, a crosslinkable monomer and another monomer, and a dispersion comprising an oily substance. Forming an emulsion containing the phase; subjecting the emulsion to a polymerization treatment of the monomer component under heating,
Forming solid polymer particles having an inner core made of the oily substance and an outer shell made of a polymer of the monomer component;
Next, a method for producing a hollow polymer, which comprises removing oily substances in the solid polymer particles, has been proposed.
In the same publication, as a method for forming an emulsion containing a dispersed phase consisting of the above-mentioned monomer component and oily substance, a homogeneous mixed liquid consisting of the above-mentioned monomer component and oily substance is immiscible with the homogeneous mixed liquid. And a method comprising producing an emulsion containing swellable seed particles as a dispersed phase, and then allowing the seed particles to absorb a monomer component and an oily substance. I have.

[0004]

SUMMARY OF THE INVENTION The present inventors have studied the method for producing hollow polymer particles described in Japanese Patent Publication No. H5-40770, and as a result, it is difficult to employ this method industrially. It turned out to be still inappropriate. That is, when producing a hollow polymer particles using an emulsion formed by dispersing a homogeneous mixed solution composed of a monomer component and an oily substance in an immiscible liquid with stirring, a desired particle size is obtained. It is still difficult to obtain an emulsion with good reproducibility and stability, the selectable range of the particle size of the hollow polymer particles that can be produced is large, and some particles in the emulsion float during production, It turned out that the phenomenon of sedimentation and separation may become significant. The separation phenomenon of some of the particles is caused by dispersing a uniform mixed solution composed of a monomer component and an oily substance in an immiscible liquid under stirring, and the particle size of the dispersed phase is reduced. When the specific gravity difference between the dispersoid (the homogeneous mixture) and the dispersion medium (the immiscible liquid) is large due to the lack of uniformity, particles having a relatively large particle size due to distribution are It was found to separate. Further, when producing hollow polymer particles using an emulsion formed by absorbing the monomer component and the oily substance into the seed particles after producing the emulsion containing the seed particles, when forming the seed particles, Since polymerization is necessary, the process must be complicated, and the absorption amount of the monomer component and the like to the seed particles tends to be non-uniform. It has been found that it is difficult to produce hollow polymer particles having a desired particle size with good reproducibility.

[0005] The present invention relates to the above-mentioned Japanese Patent Publication No. 5-40.
An object of the present invention is to provide an improved method for producing hollow polymer particles via solid polymer particles utilizing an emulsion containing a dispersed phase composed of a monomer component and an oily substance, as described in JP-A-770. Things. That is, the first object of the present invention is to produce solid polymer particles having a desired particle size with good reproducibility by making the particle size of the dispersed phase in the emulsion uniform in a simple step. It is an object of the present invention to provide an improved method for producing solid polymer particles which enables the following. The second object of the present invention is to make it possible to easily and reproducibly produce hollow polymer particles having a desired particle diameter by using the improved production method of the solid polymer particles. It is an object of the present invention to provide an improved method for producing such hollow polymer particles.

[0006]

According to the present invention, the first object described above includes the following steps (a) and (b):

(A) 0.05 to 70 parts by weight of a hydrophilic monomer, 0 to 20 parts by weight of a crosslinkable monomer and 100 parts by weight of a monomer component composed of other monomers, and an oily substance 1
The homogeneous mixture (A) consisting of 1000 parts by weight is injected into the liquid (B) which is immiscible with the homogeneous mixture (A) through a microporous membrane to thereby form the homogeneous mixture (A). Producing an emulsion consisting of a dispersed phase consisting of) and a continuous phase consisting of said liquid (B);

(B) By subjecting the emulsion obtained in the above step (a) to a treatment for polymerizing the above monomer component, an inner core portion composed of the oily substance and an outer shell portion composed of the polymer of the monomer component are formed. Forming solid polymer particles having;

The problem is solved by providing a method for producing solid polymer particles, characterized by comprising:

Further, according to the present invention, the second problem is that the above-mentioned step (a), the above-mentioned step (b) and the following step (c):

(C) a step of removing oily substances in the solid polymer particles obtained in the step (b) to form hollow polymer particles having an outer shell made of a polymer of the monomer component;

The problem is solved by providing a method for producing hollow polymer particles, characterized by comprising:

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The method for producing the solid polymer particles of the present invention comprises:
As described above, the method includes a step (a) of forming an emulsion using a monomer component-containing homogeneous mixture as a dispersed phase and a step (b) of forming solid polymer particles by a polymerization operation of the monomer component.

[0015] The monomer component used in the present invention is 0.05% based on 100 parts by weight of the entire monomer component.
Consist of ７０70 parts by weight of hydrophilic monomer, 0-20 parts by weight of crosslinkable monomer and the balance (ie 10-99.95 parts by weight) of other monomers. The hydrophilic monomer used in the present invention is a monomer having one polymerizable functional group in the molecule and having a hydrophilic property. The degree of hydrophilicity is not necessarily limited, but generally, the solubility in water is preferably 0.5% by weight or more at 25 ° C., particularly preferably 1% by weight or more. .

Examples of the hydrophilic monomer include hydrophilic acrylic acid esters such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methyl acrylate, methyl methacrylate, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. Hydrophilic methacrylic acid ester; unsaturated nitrile such as acrylonitrile; acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide; unsaturated such as acrylic acid, methacrylic acid, itaconic acid and fumaric acid Carboxylic acids; exemplified by hydrophilic vinyl monomers such as unsaturated heteroaromatic compounds such as vinylpyridine Door can be. Among these, hydrophilic methacrylates such as dimethylaminoethyl methacrylate, methyl methacrylate, glycidyl methacrylate, and 2-hydroxyethyl methacrylate;
Methacrylic acid; vinylpyridine and the like are particularly preferred.

The proportion of the hydrophilic monomer used can be arbitrarily set within the above range. When the usage ratio of the hydrophilic monomer is less than 0.05 parts by weight based on 100 parts by weight of the total monomer components, the weight to be formed along with the polymerization of the monomer components in the solid polymer particle forming step (b). The phase separation between the coalesced part and the oily substance part does not occur, or the phase separation becomes insufficient, and as a result, the polymer part does not completely encapsulate the oily substance part, and the outer shell made of the polymer The problem arises that the formation of solid polymer particles having a core part and an inner core part composed of an oily substance is incomplete. When the usage ratio of the hydrophilic monomer is more than 70 parts by weight based on 100 parts by weight of the total monomer components, the polymer does not have an inner core portion composed of an oily substance in addition to the solid polymer particles (that is, the polymer alone). A) by-produced particles in large amounts, or the strength of the outer shell portion of the obtained solid polymer particles or hollow polymer particles becomes insufficient and the particles are easily crushed. Although the optimum usage ratio of the hydrophilic monomer depends on the type of the oily substance used in combination, the usage ratio of the hydrophilic monomer is usually within the range of 0.1 to 50 parts by weight based on 100 parts by weight of all the monomer components. When selecting, better results are more likely to be obtained.

In the present invention, the crosslinkable monomer is a monomer which may be optionally used. Crosslinkable monomers are
It means a monomer having two or more polymerizable functional groups in a molecule. Examples of the crosslinkable monomer include divinyl or trivinyl monomers such as divinylbenzene, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate. Among them, divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and the like are particularly preferable. The proportion of the crosslinkable monomer used is 2 per 100 parts by weight of all monomer components.
If the amount is more than 0 parts by weight, there arises a problem that particles obtained after the polymerization treatment have a polymer network structure (that is, a porous structure) inside.

In the present invention, as the monomer component,
A monomer that is distinguished from the hydrophilic monomer and the crosslinkable monomer as described above is further used. Such other monomer may be a monomer having one polymerizable functional group in a molecule and having a non-hydrophilic property. Among the monomers, those having radical polymerizability include unsaturated aromatic hydrocarbon compounds such as styrene, α-methylstyrene, p-methylstyrene, and halogenated styrene;
Vinyl esters such as vinyl acetate and vinyl propionate; non-hydrophilic unsaturated carboxylic acid alkyl esters such as ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate and lauryl methacrylate Conjugated diolefins such as butadiene and isoprene;

The oily substance used in the present invention is not particularly limited as long as it is liquid at about normal temperature, does not substantially polymerize under the polymerization conditions employed in the present invention, and has lipophilicity. The degree of lipophilicity is not necessarily limited, but the solubility in water is 25 ° C.
Is preferably 0.2% by weight or less. In the present invention, for the purpose of obtaining hollow polymer particles, a relatively volatile hydrocarbon solvent such as benzene, toluene, xylene, butane, pentane, hexane, heptane, hexadecane and cyclohexane may be used as the oily substance. It is preferable because oily substances can be easily removed from the solid polymer particles after the polymerization treatment. Further, in the present invention, depending on the intended use of the obtained solid polymer particles or hollow polymer particles, as an oily substance, citronellal, geraniol, eugenol, cyclamenaldehyde, dibutyl phthalate,
A high boiling oily substance such as dioctyl phthalate can be used alone or together with the above-mentioned hydrocarbon solvents. The use of the high-boiling point oily substance exemplified above makes it possible to produce microcapsule-shaped polymer particles containing a fragrance, a plasticizer, and the like. Further, in the present invention, in the oily substance as described above, dyes, paints, inks, fragrances, adhesives, detergents, pharmaceuticals, pesticides,
Dissolve or disperse substances other than oily substances that are easily affected by oxygen, evaporation, pressure, aggregation, etc., such as fertilizers, oils and fats, foods, enzymes, liquid crystals, recording materials, magnetic substances, catalysts, and chemical reactants. By using as an oily substance, it is also possible to obtain particles in which the above-mentioned fragile substance is physically protected in a capsule.

The amount of the oily substance used is 100
It is in the range of 1 to 1000 parts by weight, preferably 10 to 300 parts by weight based on parts by weight. If the use ratio of the oily substance is too small, the particles obtained after the polymerization treatment have insufficient inner core portions. On the other hand, if the use ratio of the oily substance is too large, the particles obtained after the polymerization treatment have a problem that the film thickness of the outer shell made of the polymer is thinner than the particle diameter, and the particles are easily crushed.

The homogeneous mixture (A) used in the present invention can be prepared by mixing the above monomer component and the above oily substance. In the mixing, various methods such as stirring and shaking can be appropriately selected and employed according to a conventional method.

In the present invention, the above homogeneous mixture (A)
A liquid (B) that is immiscible with the homogeneous mixture (A).
Press into it through a microporous membrane. The liquid (B) used here is not particularly limited as long as it is substantially immiscible with the homogeneous liquid mixture (A), but is usually water; ethylene glycol, glycerin, ethanol, methanol The use of an aqueous and / or alcohol-based solvent such as a mixed solvent of water and an alcohol as a main component provides high quality of the obtained solid polymer particles or solid polymer particles, and versatility of the solvent. It is preferable in terms of the height of the film.

It should be noted that it is easy to obtain good results when one or more additives such as a surfactant and a suspension stabilizer are mixed in the liquid (B). For example, when a suspension stabilizer is used, the generation of agglomerates during polymerization is reduced, so that polymer particles having a more uniform particle size are easily obtained.

The above-mentioned surfactants include, for example, anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dialkylsulfosuccinate, and formalin condensate of naphthalenesulfonic acid; alkyl ammonium salts, alkylbenzyl ammonium Salt, betaine, imidazolium betaine,
Cationic surfactants such as lecithin; and nonionic surfactants such as polyoxyethylene nonylphenol ether, polyethylene glycol monostearate and sorbitan monostearate. When a surfactant is used, the amount of the surfactant used is 0.1 to the liquid (B).
It is preferable that the content is in the range of 1 to 10% by weight in view of stability of the emulsion, economy, purity of solid polymer particles obtained after polymerization, and the like. As the above suspension stabilizer, an organic or inorganic one can be used.
Examples of the organic suspension stabilizer include hydrophilic synthetic polymer substances such as polyvinyl alcohol, polyvinyl vilolidone, and polyethylene glycol; and hydrophilic semi-synthetic polymer substances such as carboxymethyl cellulose. Also,
Examples of the inorganic suspension stabilizer include phosphates such as magnesium, barium, and calcium; calcium carbonate, magnesium carbonate, zinc white, aluminum oxide, and aluminum hydroxide. When a suspension stabilizer is used, the amount of the suspension stabilizer is 0.1% with respect to the liquid (B).
It is preferable that the content is within the range of 20 to 20% by weight in view of the stability of the emulsion, economy and the like.

If necessary for the subsequent polymerization of the monomer components, the above-mentioned homogeneous mixture (A), the above-mentioned liquid (B), or both of them may be added to a polymerization initiator, a chain transfer agent, a polymerization inhibitor or the like. Or one or more of the various additives described above. As the polymerization initiator, any one can be appropriately used according to the type of polymerization method, the type of the monomer component, and the like, but does not have an inner core made of an oily substance during the subsequent polymerization treatment (ie, It is preferable to use an oil-soluble polymerization initiator in order to suppress the by-product of particles (composed of only a polymer). Preferred polymerization initiators include, for example, acyloyl peroxide such as benzoyl peroxide and lauroyl peroxide; organic peroxyalkyl esters such as cumene hydroperoxide, t-butyl perbenzoate and isopropyl peracetate; di-t-butyl peroxide And azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and azobiscarbonitrile such as 2,2′-azobis (2,4-dimethylvaleronitrile). A redox polymerization initiator obtained by combining a peroxide and a reducing agent as a polymerization initiator;
Photopolymerization initiators such as α, α-dimethoxy-α-monophorino-methylthiophenylacetophenone, 2,4,6-trimethylbenzoylphosphine oxide, benzophenone, thioxanthone, and tetramethylthiuram monosulfide can also be used. When a polymerization initiator is used, the amount of the polymerization initiator can be set according to a usual polymerization method, but is generally in the range of 0.05 to 10 parts by weight based on 100 parts by weight of the monomer component. , Preferably in the range of 0.5 to 3 parts by weight.

In the present invention, in order to disperse the homogeneous liquid mixture (A) in the liquid (B), the homogeneous liquid mixture (A) is pressed into the liquid (B) through a microporous membrane. This makes it possible to prepare an emulsion in which particles of the homogeneous mixture (A) are dispersed in a continuous phase of the liquid (B) with a highly uniform particle diameter. By the subsequent polymerization treatment, uniform solid polymer particles (and even uniform hollow polymer particles) can be obtained. The method of preparing an emulsion using such a microporous film is called a "Shirasu Porous Glass (SPG) method" and is a known method (see, for example, JP-A-2-95433).

The microporous membrane used in the present invention must have a pore size commensurate with the particle size of the target polymer particles, and the uniformity of the pore size must be at least a certain value. It is preferable to obtain solid polymer particles or hollow polymer particles having a narrow particle size distribution. In addition, the material of the microporous membrane has a greater wettability to the liquid (B) than a wettability to the homogeneous mixed liquid (A), which means that an emulsion having a highly uniform dispersed particle diameter can be formed (and, consequently, an emulsion having a highly uniform dispersed particle diameter). From the viewpoint of formation of polymer particles having high uniformity in particle diameter). In order to adjust the wettability, if necessary, the surface of the microporous film may be chemically or chemically modified to make it hydrophobic or hydrophilic. In addition, the microporous membrane has sufficient mechanical strength to prevent deformation or destruction at the time of press-fitting, and has chemical durability to the homogeneous mixed liquid (A) and liquid (B). Needless to say, what you do is required. As described above, the degree of uniformity of the pore diameter, which is preferable in the microporous membrane, is not necessarily limited, but the pore diameter distribution of the porous membrane is determined by a relative cumulative pore diameter distribution curve (pore diameter− in the graph) of the cumulative pore volume, the pore diameter (phi _{1 0)} when the integrated value of the pore volume is 10% in the total pore volume basis from towards larger pore diameters, in the same integrated value SFAS 90%
It is generally preferred that the value divided by the pore diameter (φ ₉₀ ) at the time of the above is in the range of 1 to 2.5.

Microporous Membrane Suitable for Use in the Present Invention
For example, alumina, zirconia, magnesium
A, Araldite, Carborundum or other ceramics
And more specifically, a porous film-shaped molded product, more specifically,
CaO-B₂O₃-SiO₂-Al₂O₃System porous glass
(See JP-B-62-25618), CaO-B
₂O₃-SiO₂-Al₂O₃-Na₂O-based porous glass
, CaO-B₂O₃-SiO₂-Al₂O₃-Na₂
O-MgO-based porous glass (JP-A-61-40841)
Japanese Patent Application Laid-Open (JP-A) No. 2000-131, etc.)
No. Membranous molded body made of the above porous glass
Has a particularly high pore size uniformity and the desired polymer
-Obtain a molded product having an average pore size adapted to the particle size
It is preferable because it is easy. The above microporous membrane is necessary
Depending on the use of a silylating agent, a silane coupling agent, etc.
Surface-treated. Microporous membrane
The shape of the plate is not limited to a
An arbitrary shape such as a cylindrical shape or a funnel shape can be appropriately selected.
Wear. The thickness of the microporous membrane is not necessarily limited.
Although it is not something that is
In general, it is preferable to set it within the range of about 0.4 to 2 mm.
No.

The press-fitting of the homogeneous mixed solution (A) into the liquid (B) through the microporous membrane is performed by reducing the pressure on the surface of the microporous membrane on the side of the homogeneous mixed solution (A). This can be done by increasing relative to the pressure on the liquid (B) side of the membrane. The pressure difference between the homogeneous mixture (A) and the liquid (B) on both sides of the microporous membrane is:
It can be appropriately selected according to the type of the homogeneous mixture (A), the pore size of the microporous membrane, the type of the liquid (B), and the like. Specific means for injecting the homogeneous mixed solution (A) into the liquid (B) through the microporous membrane is not necessarily limited, but for example, mechanical pressurizing means such as a pump; nitrogen And a pressurizing unit for the homogeneous mixed liquid (A), such as a pressurizing unit via a gas such as air. In addition, decompression means for the liquid (B) is also effective as a means for injecting the homogeneous mixture (A).

When the homogeneous mixed liquid (A) is injected into the liquid (B), the mixing ratio of the two depends on the productivity and the uniformity of the particle diameter of the dispersed particles in the obtained emulsion (therefore, the polymer particles obtained after polymerization). Particle size uniformity)
In view of the above, the homogeneous mixed liquid (A) is the liquid (B) 1
The ratio is preferably in the range of 1 to 100 parts by weight, more preferably in the range of 5 to 100 parts by weight with respect to 00 parts by weight.

The injection of the homogeneous mixture (A) into the liquid (B) can be carried out in a continuous manner while allowing the liquid (B) to flow while being in contact with one surface of the microporous membrane.
Batch operation is also possible. When the homogeneous mixed liquid (A) is injected into the liquid (B), the dispersed phase composed of the homogeneous mixed liquid (A) is promoted to be detached from the microporous membrane, and the resulting emulsion In order to prevent aggregation and sedimentation of the dispersed phase, it is preferable to flow the emulsion by means such as stirring, circulation, and distribution.

In the present invention, after the emulsion is prepared in the step (a) as described above, the emulsion is subjected to a polymerization treatment in the step (b). In the polymerization treatment, a polymer layer is formed at the interface (near the surface) of the dispersed phase due to the presence of the hydrophilic monomer by polymerizing the monomer component contained in the dispersed phase in the emulsion. As a result, solid polymer particles having an outer shell made of a polymer and an inner core made of an oily substance are formed in the continuous phase made of the liquid (B).

The above polymerization treatment can be carried out according to a usual polymerization method, but in many cases, it can be carried out according to a suspension polymerization method. At this time, the type of the reactor, the stirring method, etc. are not particularly limited and can be appropriately set, and the temperature used for initiating and proceeding the polymerization, the conditions such as energy beam irradiation, etc. It can be appropriately determined according to the initiator and the like.

In the above polymerization treatment, a water-soluble polymer, a surfactant, a chain transfer agent, a polymerization inhibitor and the like may be added to the emulsion as required. As the water-soluble polymer or the surfactant, the one added as a suspension stabilizer or a surfactant in the above step (a) may be used as it is, or may be newly added at the time of polymerization. Good. When the surfactant is contained in the polymerization system, the content thereof is 0.1 to 0.1 with respect to the continuous phase composed of the liquid (B).
Preferably it is in the range of 10% by weight. When the polymerization system contains a suspension stabilizer, its content is preferably in the range of 0.1 to 20% by weight based on the continuous phase of the liquid (B).

In the method for producing solid polymer particles according to the present invention, an emulsion in which the solid polymer particles are dispersed in the liquid (B) is obtained by the above polymerization treatment. The solid polymer particles are separated and obtained, if necessary, by removing the dispersion medium in the emulsion. When the oily substance in the solid polymer particles is less likely to evaporate than the dispersion medium or has a high boiling point, the emulsion after the polymerization treatment is subjected to a drying treatment under normal pressure or reduced pressure conditions, whereby Real polymer particles can be separated and obtained. In the drying treatment, if necessary, heating conditions can be adopted. As a method for removing the dispersion medium, for example, a known method suitable for the particle diameter of the obtained polymer particles, such as an acid precipitation method, a salting out method, a freeze coagulation method, a spray drying method, a filtration method, and a centrifugation method, is employed. can do.

In the method for producing hollow polymer particles according to the present invention, in step (c), the solid polymer particles obtained in step (b) are subjected to an oily substance removal treatment. The solid polymer particles to be subjected to the oily substance removal treatment may be solid polymer particles dispersed in the emulsion obtained by the polymerization treatment according to the above step (b), or may be separated and obtained from the emulsion. Solid polymer particles. As a treatment for removing the oily substance from the solid polymer particles separated and obtained, for example, a method comprising evaporating the oily substance by a drying treatment is preferable. Further, the removal of the oily substance and the dispersion medium from the solid polymer particles dispersed in the emulsion may be performed by blowing a gas such as air, nitrogen gas, or steam into the emulsion. And a method using these means in combination.

According to the present invention, by selecting the pore diameter of the microporous membrane to be used, for example, 0.1 to 100 μm
It is possible to produce solid polymer particles or hollow polymer particles having any average particle size from a wide range from a relatively small average particle size to a relatively large average particle size, such as within the range of m. . Also, by selecting the usage ratio between the monomer component and the oily substance,
Solid polymer particles or hollow polymer particles having an arbitrary ratio from a wide range of the thickness ratio of the outer shell portion made of a polymer can be produced. Thus, the size of the solid or hollow polymer particles that can be produced according to the present invention can vary widely. Moreover, not only when the average particle diameter is relatively small, but also when the average particle diameter is relatively large, for example, 5 μm or more, solid polymer particles or hollow polymer particles having a uniform particle diameter can be easily formed by a simple process. And it can be manufactured with good reproducibility.
The solid polymer particles obtained by the method of the present invention are fragrances, chemicals, agricultural chemicals,
As microcapsule particles containing ink components and the like,
It can be used for various purposes depending on the active ingredient contained therein. Further, it can be used as an intermediate material in the method for producing hollow polymer particles according to the present invention. The hollow polymer particles obtained by the method of the present invention have a wide range of application in their dimensions, high uniformity of particle diameter, etc.
It is useful as a plastic pigment excellent in gloss and hiding power, a light scattering agent, and the like. The hollow polymer particles obtained by the method of the present invention are particularly lightweight, uniform, and have characteristics not found in ordinary polymer particles in terms of optical characteristics such as light refractive index and reflectance. It can be suitably used for various uses as an organic filler, such as a filler for a coating composition, an absorbent filler for ink-jet paper, a gap adjusting material, and a filler for a composition requiring weight reduction.
Further, under normal pressure, by means of immersion treatment under reduced pressure or under pressure, the fragrance, chemicals, agricultural chemicals,
By encapsulating an active ingredient such as an ink component into microcapsule particles, it can be used for various purposes depending on the active ingredient contained therein.

[0039]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 12.75 g of styrene and 0.25 g of dimethylaminoethyl methacrylate as monomer components, 7.0 g of hexadecane as an oily substance, and 2,2'-azobis (2,4-dimethyl) as a polymerization initiator (Valeronitrile) 0.1 g was mixed to prepare a homogeneous mixed solution (A-1). Further, 230 g of distilled water, 1.0 g of polyvinylpyrrolidone (Mw: 40000), 0.075 g of sodium lauryl sulfate, 0.1 g of sodium sulfate and 0.1 g of sodium nitrite are dissolved and mixed to form a mixed solution (B-1).
Was prepared. A stainless steel outer cylinder and a porous glass cylinder inside (pore diameter of porous glass = 1.42 μm,
Outer diameter of cylinder = 9.85 mm, inner diameter of cylinder = 8.15 m
m, an effective length of a cylinder = approximately 100 mm), a membrane module comprising a cylindrical module, a water tank, and a circulating pump connected by a Teflon (registered trademark) tube to form a circuit (MPG emulsion sold by Ise Chemical Industry Co., Ltd.) Using a mini experimental apparatus "), an emulsion composed of the dispersed phase composed of the homogeneous liquid mixture (A-1) and the continuous phase composed of the mixed liquid (B-1) was prepared. That is, the mixed solution (B-1) is put into the water tank and supplied to one end of a porous glass cylindrical inner passage of the cylindrical module via a circulation pump. The effluent from the other end was returned to the water tank. In this way, while circulating the mixture (B-1) through the porous glass cylindrical inner passage of the cylindrical module, the uniform mixed liquid (B-1) is introduced into the inlet of the porous glass cylindrical outer passage of the cylindrical module. A-1) was injected with a pressure difference of 44.1 kPa. The emulsion thus obtained is placed in a separable flask having a capacity of 1000 ml, and is polymerized for 16 hours by heating at a temperature of 70 ° C. while stirring at a rotation speed of 160 rpm under a nitrogen atmosphere to contain polymer particles. An emulsion was prepared. The polymer yield in this polymerization reaction is 64
%Met. Observation of the obtained emulsion with an optical microscope revealed that the polymer particles constituting the dispersed phase were spherical microparticles consisting of an inner core of a liquid phase mainly composed of the above-mentioned oily substance (hexadecane) and an outer shell of a polymer covering the outside. The polymer particles are capsule-shaped particles, the average value of the particle size of the polymer particles is 6 μm, and the coefficient of variation (CV value) is 8.7%.
Was confirmed. An optical microscope photograph of the obtained emulsion is shown in FIG. Then, one drop of the emulsion obtained by the above-described process is placed on a sample table for a scanning electron microscope (SEM) on which an aluminum foil tape is mounted, and left overnight at room temperature in a desiccator. ,
Low-boiling substances such as water in the emulsion dispersion medium, oily substances and unreacted monomer components in the polymer particles were evaporated. After the particles remaining on the sample stage were sputtered for 2 minutes under the condition of a pressure of 13.3 Pa, the particles were observed by SEM. As a result, it was confirmed that the particles were almost true hollow polymer particles having voids inside. Was done. The electron micrograph is shown in FIG. In addition, one of the particles in FIG. 2 is a broken particle (however, the broken particle is very rarely present). Can be.

Comparative Example 1 This comparative example is an experimental example in which polymer particles were produced without using a hydrophilic monomer. 5.00 g of styrene as a monomer component, 2.51 g of 2-ethylhexyl acrylate and 1.50 g of divinylbenzene, 7.0 g of hexadecane and 0.70 g of lauryl alcohol as oily substances, and 0.55 g of benzene peroxide as a polymerization initiator And a homogeneous mixture (A-
2) was prepared. In addition, 220 g of distilled water, 2.5 g of polyvinyl alcohol, and sodium lauryl sulfate 0.17
g, 0.05 g of sodium sulfate and 0.04 g of hydroquinone were dissolved and mixed to prepare a mixed solution (B-2). Using the same type of film emulsifying apparatus as that used in Example 1, an emulsion comprising the dispersed phase consisting of the homogeneous mixed solution (A-2) and the continuous phase consisting of the mixed solution (B-2) was prepared. . However, the pressure difference at the time of press-fitting the homogeneous mixture (A-2) was set to 56.1 kPa. The obtained emulsion is placed in a separable flask having a capacity of 1000 ml, and is polymerized for 20 hours by heating at a temperature of 70 ° C. while stirring at a rotation speed of 160 rpm under a nitrogen atmosphere to produce an emulsion containing polymer particles. did. The yield in this polymerization reaction was 64%. When the obtained emulsion was observed with an optical microscope, the average value of the particle size of the polymer particles constituting the dispersed phase was 8 μm, and the coefficient of variation (CV value) was 17%.
Was confirmed. In this observation, it was not possible to confirm whether or not the polymer particles were microcapsule-like particles. FIG. 3 shows an optical microscope photograph of the obtained emulsion. Next, one drop of the obtained emulsion is placed on a sample stage for a scanning electron microscope (SEM) on which an aluminum foil tape is mounted, and left overnight at room temperature in a desiccator to disperse the emulsion. Low boiling substances such as water in the medium, oily substances and unreacted monomer components in the polymer particles were evaporated. The particles remaining on the sample stage were sputtered for 2 minutes under the condition of a pressure of 13.3 Pa, and then observed by SEM. As a result, although the particles were almost perfectly spherical polymer particles, a clear void was formed inside the polymer particles. Was not formed. The electron micrographs are shown in FIGS. FIG.
Fig. 5 is an electron micrograph of particles having no deficiency, and Fig. 5 is an electron micrograph of particles partially deficient. It can be seen that no hollow structure is observed in any of the particles.

According to this comparative example, when the hydrophilic monomer was not used, even if an emulsion was formed using a film emulsifying apparatus, the aggregation of the oily substance in the dispersed phase during polymerization was insufficient. The polymer particles obtained after the polymerization are such that the oily substance is widely dispersed and distributed throughout the particles, and the particles obtained by subjecting the polymer particles to a low-boiling-point evaporation operation are integrated. It is presumed that the void portion no longer forms.

Comparative Example 2 19.125 g of styrene and 0.375 g of dimethylaminoethyl methacrylate as monomer components, 10.5 g of hexadecane as an oily substance, and 2,2'-azobis (2,4-dimethyl 0.15 g of valeronitrile) was mixed and mixed uniformly (A-
3) was prepared. 345 g of distilled water, 1.5 g of polyvinylpyrrolidone (Mw: 40000), 0.1125 g of sodium lauryl sulfate, 0.15 g of sodium sulfate
And 0.15 g of sodium nitrite were dissolved and mixed to prepare a mixed solution (B-3). The above homogeneous mixture (A-3)
And the above mixture (B-3) was stirred with a stirring emulsifier (MTEC).
HNIQUE), and the mixture was mechanically stirred at 5000 rpm for 15 minutes to obtain the homogeneous mixture (A-3).
And a continuous phase consisting of the mixed solution (B-3). The emulsion thus obtained is placed in a separable flask having a capacity of 1000 ml, and rotated at 160 rpm under a nitrogen atmosphere.
The polymerization was carried out for 18 hours by heating at a temperature of 75 ° C. while stirring at pm to produce an emulsion containing polymer particles. The yield in this polymerization reaction was 55%. Observation of the obtained emulsion with an optical microscope revealed that the polymer particles constituting the dispersed phase were spherical microparticles consisting of an inner core of a liquid phase mainly composed of the above-mentioned oily substance (hexadecane) and an outer shell of a polymer covering the outside. The polymer particles are capsule-shaped particles, the average value of the particle size of the polymer particles is 5 μm, and the coefficient of variation (CV value) is 5
It was confirmed that it was 5.1%. An optical microscope photograph of the obtained emulsion is shown in FIG.

From this comparative example, it can be seen that in the method of preparing an emulsion by mechanical stirring, the polymer particles obtained after polymerization have low particle size uniformity (CV value: 20% or more).

[0045]

According to the present invention, there is provided an improved method for producing solid polymer particles having an outer shell made of a polymer and an inner core made of an oily substance, and a method for producing a solid polymer from the polymer via the solid polymer particles. An improved method for producing hollow polymer particles having an outer core and a single void is provided. According to the present invention, solid polymer particles and hollow polymer particles having good particle size uniformity (that is, narrow particle size distribution) can be produced with a simple operation with good reproducibility.

[Brief description of the drawings]

FIG. 1 is an optical micrograph of an emulsion obtained after a polymerization treatment in Example 1 according to the present invention.

FIG. 2 is an electron micrograph of hollow polymer particles obtained through a polymerization treatment and a low-boiling matter evaporation treatment in Example 1 according to the present invention.

FIG. 3 is an optical micrograph of an emulsion obtained after a polymerization treatment in Comparative Example 1 other than the present invention.

FIG. 4 is an electron micrograph of polymer particles having no deficiencies obtained through a polymerization treatment and a low-boiling matter evaporation treatment in Comparative Example 1 other than the present invention.

FIG. 5 is an electron micrograph of a partially missing polymer particle obtained through a polymerization treatment and a low-boiling matter evaporation treatment in Comparative Example 1 other than the present invention.

FIG. 6 is an optical micrograph of an emulsion obtained after a polymerization treatment in Comparative Example 2 other than the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Keiji Kubo 41 Miyukigaoka, Tsukuba, Ibaraki Pref., Kuraray Co., Ltd. (72) Inventor Takashi Yamashita 41 Miyukigaoka, Tsukuba, Ibaraki Pref., Kuraray Co., Ltd. (72 Inventor Yoshiki Mukao 41 Miyukigaoka, Tsukuba-shi, Ibaraki F-term in Kuraray Co., Ltd. DB04 DB27 LA02 LA03 LA04 LA06 LB05 LB10

Claims (2)

[Claims] 1. The following steps (a) and (b): (a) 0.05 to 70 parts by weight of a hydrophilic monomer, 0 to 20 parts by weight of a crosslinkable monomer and 100 parts by weight of a monomer component composed of other monomers, and oiliness The homogeneous mixture (A) consisting of 1 to 1000 parts by weight of the substance is mixed with the homogeneous mixture (A)
By press-fitting through a microporous membrane into a liquid (B), which is immiscible with water, to produce an emulsion composed of a dispersed phase composed of the homogeneous liquid mixture (A) and a continuous phase composed of the liquid (B). (B) By subjecting the emulsion obtained in the above step (a) to a process of polymerizing the above monomer component, the emulsion has an inner core portion composed of the oily substance and an outer shell portion composed of a polymer of the monomer component. Forming solid polymer particles. A method for producing solid polymer particles. 2. The following steps (a), (b) and (c): (a) a monomer component 100 comprising 0.05 to 70 parts by weight of a hydrophilic monomer, 0 to 20 parts by weight of a crosslinkable monomer, and another monomer A homogeneous mixture (A) consisting of 1 part by weight and 1 to 1000 parts by weight of an oily substance is mixed with the homogeneous mixture (A).
By press-fitting through a microporous membrane into a liquid (B), which is immiscible with water, to produce an emulsion composed of a dispersed phase composed of the homogeneous liquid mixture (A) and a continuous phase composed of the liquid (B). (B) By subjecting the emulsion obtained in the above step (a) to a process of polymerizing the above monomer component, the emulsion has an inner core portion composed of the oily substance and an outer shell portion composed of a polymer of the monomer component. (C) forming a hollow polymer having an outer shell composed of a polymer of the monomer component by removing an oily substance in the solid polymer particles obtained in the above step (b); Forming a hollow polymer particle.