JP2559894B2 - Composite hollow particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to fine particle composite hollow particles having an average particle diameter of 0.1 to 300 µm and a method for producing the same. In particular, additives as fillers, reinforcing agents, paints, inks, paints, adhesives, cosmetics, and other matting agents, fillers, reinforcing agents, moisture permeability imparting agents, and breathability imparting agents for rubber and plastics. Further, the present invention relates to fine particle composite hollow particles which can be applied to a wide range of fields such as surface modifiers for coating films and molded articles and ion exchange resins.

[Prior Art] Until now, as a method for synthesizing porous particles and hollow particles,
W / O / W suspension polymerization (Japanese Patent Laid-Open No. 61-72003) or a method of mixing an unreacted organic solvent with a monomer for suspension polymerization and removing the solvent to form porosity and reaction temperature The method of using two or more kinds of initiators different from each other is shown.

However, the above method has a problem that many surfactants are difficult to remove by post-treatment, and the above method has a problem that an unnecessary organic solvent remains in the aqueous system. Further, in the above method, even when two or more initiators are used, the second reaction process requires a high temperature of hundreds of tens of degrees, so that a special reaction vessel is required in an aqueous system.

Further, when the degree of crosslinking of the produced particles is low, the particles swell or become in a dissolved state due to mixing with the organic solvent.

On the other hand, from the viewpoint of encapsulation technology, capsules having a large number of inorganic walls and methods of synthesizing them have been shown, but these particles have low affinity with organic compounds at the interface, and some mixing is required. Furthermore, since the wall is made three-dimensional by ionic bonding or the like, there is a problem that the water resistance becomes poor when added to the paint.

[Problems to be Solved by the Invention] An object of the present invention is to provide a composite hollow particle having excellent solvent resistance and mechanical stability, having a tough membrane wall, and easily synthesized.

[Means for Solving the Problems] In order to achieve the above object, the average particle diameter is 0.01 to 5 μm.
It has been found that excellent performance can be achieved by carrying out dispersion polymerization using the above organic particles, and thus the present invention has been accomplished.

That is, the present invention includes (a) a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule, (b) a polymerizable monomer other than the monomer of (a), ( c) Organic particles having an average particle diameter of 0.01 to 5 μm, (d) a polymerization initiator, and (e) a dispersant, and a component (a) / component (b) weight ratio of 0.5 / 99.5 to 60/40. Yes, component (c) is component (a)
And an average particle size of 0.1 to 300μ obtained by dispersion polymerization of 1 to 50% by weight based on the total weight of (b) in an aqueous medium.
Provided is a composite hollow particle in which a hollow particle of m and an organic particle having an average particle diameter of 0.01 to 5 μm are combined.

The composite hollow particles of the present invention are prepared by blending organic particles having an average particle size of 0.01 to 5 μm during radical polymerization of a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule and another monomer. It is obtained by doing. In the present specification, “hollow particles” can be defined as particles in which one or more bubbles are present. The bubbles within the particles can be in the form of either closed cells or open cells. Although it is difficult to measure the porosity of bubbles accurately, when observing the cross section of particles with an electron microscope and measuring the cross section of cavities in the particle cross section, 1 to 95%, preferably 5
~ 80%. Although it is not known why voids are generated in the particles, particles having voids can be obtained by dispersion polymerization of the four components.

On the other hand, since organic particles having an average particle size of 0.05 to 5 μm are also granulated while existing in the polymerization system, they are taken into the hollow particles, adhere to the surface of the hollow particles, or in various states inside and outside the hollow particles. To remain. Therefore, in this specification, the term "composite" means that the organic particles of 0.05 to 5 μm remain in various forms inside and outside the hollow particles.

Examples of the monomer (a) having two or more radically polymerizable ethylenically unsaturated groups in the molecule used for producing the composite hollow particles of the present invention include, for example, polymerizable unsaturated carboxylic acid ester of polyhydric alcohol. , Polymerizable unsaturated alcohol esters of polybasic acids, and aromatic compounds substituted with two or more vinyl groups. Specifically, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3
-Butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-
Hexanediol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimetacrylate, pentaerythritol tetramethacrylate, glycerol dimethacrylate, glycerol diacrylate, glycerol acloxydimethacrylate 1,1,1-Trishydroxymethylethane diacrylate, 1,1,1-Trishydroxymethylethane triacrylate, 1,1,1-Trishydroxymethylethane dimethacrylate, 1,1,1-Trishydroxymethylethane Trimethacrylate, 1,1,1-trishydroxymethylpropane diacrylate, 1,1,1-trishydroxymethylpropane triacrylate Over DOO, 1,1,1-tris hydroxymethyl propane dimethacrylate, 1,1,
Examples thereof include 1-trishydroxymethylpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate and divinylbenzene.

Further, in the present invention, at least one polymerizable monomer (b) other than the above-mentioned monomers is used. As such a monomer, for example, a carboxyl group-containing monomer,
For example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and the like, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate,
Hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methallyl alcohol, etc., nitrogen-containing alkyl acrylates or methacrylates, such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc., polymerizable amides,
Polymerizable nitriles such as acrylic acid amide and methacrylic acid amide such as acrylonitrile and methacrylonitrile, alkyl acrylates or methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n
-Butyl methacrylate, 2-ethylhexyl acrylate and other polymerizable aromatic compounds such as styrene and α-
Examples include methylstyrene, vinyltoluene, t-butylstyrene and the like, α-olefins such as ethylene and propylene, vinyl compounds such as vinyl acetate and vinyl propionate, and diene compounds such as butadiene and isoprene.

The organic particles (c) having an average particle diameter of 0.01 to 5 μm used in the present invention may be crosslinked particles or non-crosslinkable particles. These particles may be obtained by any method. Examples of suitable organic particles include, for example, JP-A-
Examples thereof include those described in JP-A-58-129065 and JP-A-58-129066. If the particle size of the particles is 0.01 μm or less, the void area ratio in the particles is extremely low, and if it exceeds 5 μm, the polymerized particles and the added particles are mixed in water, and the particles cannot be synthesized. It has the drawback.

The polymerization initiator (d) may be any one as long as it has the ability to initiate polymerization, but is preferably oil-soluble.
Examples of such a polymerization initiator include azo-based initiators such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azobis (2-cyclopropylproton). Pionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionitrile) (2,2'-azobisisobutyronitrile), 2 , 2'-Azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitryl), 2-phenylazo-4-methoxy-2,4-
Dimethylvaleronitrile, etc .; Diacyl peroxide initiators, such as isobutyryl peroxide, 2,4-
Dichlorobenzoyl peroxide, o-methylbenzoyl peroxide, lauroyl peroxide, etc .; Percarbonate-based initiators such as di-3-methoxybutylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl Peroxydicarbonate etc .; Ketone peroxide type initiators such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide etc .; Hydroperoxide type initiators such as 2,4,4-trimethylpentyl 2-hydroperoxide, diisopropylbenzene hydroperoxide, cumene peroxide, etc .; dialkyl peroxide initiators such as dicumyl peroxide, 2,5-di Chill-2,5-di (t-butylperoxy) hexane, t- butyl cumyl peroxide,
Di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3, tris (t-
Butylperoxy) triazine and the like; peroxyketals such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,2-di (t-butylperoxy) butane, 4, 4-di-t-butylperoxyvaleric acid n-butyl ester and the like; and alkylperester-based initiators such as 2,4,4-trimethylpentylperoxy-
Examples include phenoxyacetate, α-cumylperoxy neodecanoate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxy-hexahydroterephthalate.

The dispersant (e) used in the present invention is (a) to (a) above.
Each component of (d) is dispersed in an aqueous medium, and if necessary, a dispersion stabilizer and / or an emulsifier may be used in combination.
Examples of such a dispersant include polyvinyl acetate or a modified product thereof (for example, polyvinyl alcohol), or a polymer dispersant having a hydrophilic group and a hydrophobic group synthesized from a monomer having an ethylenic substance. To be Specifically, for example, KM-11 (Nippon Gosei Kagaku), N
H-20 (Nippon Gosei Kagaku), polyvinylpyrrolidone, GH
-17 (Nippon Gosei Kagaku Co., Ltd.) and the like.

Examples of the surfactants include anionic alkyl sulfonates and the like, nonionic polyoxyethylene nonylphenyl ethers, polyoxyethylene alkyl ethers and the like and cationic benzyl ammonium salts.

Examples of the aqueous medium include water, preferably deionized water.

In the blending amounts of (a) to (e), the weight ratio (a) / (b) of the monomer of (a) to the monomer of (b) is
It is 0.5 / 99.5-60 / 40. If the weight ratio is less than 0.5 / 99.5, the degree of three-dimensional crosslinking decreases and the porosity per particle volume of the present invention decreases. On the other hand, if it is more than 60/40, the yield of the hollow particles of the present invention decreases, which is not preferable.

The amount of the organic particles (c) used is 1 to 50 based on the total weight (a) + (b) of the monomers (a) and (b).
% By weight, preferably 5 to 30% by weight. If it is less than 1 wt%, the porosity per particle volume is low. On the other hand, if it is more than 50 wt%, it cannot be uniformly mixed with the monomer, and it becomes a gel, and the dispersion stability in water becomes poor and the yield decreases.

The blending amount of the dispersant of (d) above is (a) to (c) above.
1 to 20% by weight, preferably 2 to 15% by weight, based on the total weight of If it is less than 1% by weight, the dispersion stability is poor, and 20
If it exceeds 5% by weight, the viscosity becomes too high and polymerization cannot be performed.

In the polymerization method of the present invention, the components (a) to (d) are added to the aqueous medium at the same time as the dispersant (e) or after the dispersant is added. After addition, these are dispersed.
As a dispersing method, a usual method may be used, for example, stirring may be performed with a homogenizer, a disper, or the like, or a high-speed emulsifying machine may be used to reduce the particle size. This dispersion is then heated to 50-95 ° C, preferably
Stirring polymerization is carried out at 60 to 85 ° C. for 2 to 20 hours, preferably 5 to 12 hours to obtain the fine particle composite hollow particles of the present invention.

EFFECTS OF THE INVENTION According to the present invention, it is possible to easily produce fine particle composite hollow particles having excellent solvent resistance, fracture resistance, elasticity and the like.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples.

[Production Example 1] Production of emulsifier used in production of organic particles Stirrer, nitrogen introduction tube, temperature control device, condenser,
2 l Kolben with decanter, 213 parts bishydroxyethyl taurine, 236 parts 1,6-hexanediol, 296 parts phthalic anhydride, 376 parts azelaic acid, and xylene 44
Part was charged and the temperature was raised. The water generated by the reaction was removed by azeotropic distillation with xylene. The temperature was raised to 210 ° C. over about 3 hours from the start of refluxing, and stirring and dehydration were continued until the acid value corresponding to the carboxylic acid became 125 to carry out the reaction. After lowering this temperature to 140 ℃, keep this temperature,
(Shell, versatic acid glycidyl ester)
500 parts was added dropwise over 30 minutes, and then stirring was continued for 2 hours.
Production examples of organic particles are shown in Production Examples 2 to 6.

[Production Example 2] 50 parts of the emulsifier obtained in Production Example 1, 5.0 parts of dimethylethanolamine and 508 parts of deionized water were charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introducing tube, while stirring. The temperature was 80 ° C. Immediately after adding 80 parts of the following initiator solution to this, dropwise addition of the following monomer mixture was started.

Initiator solution Azobiscyanovaleric acid 2 parts Deionized water 100 parts Dimethylethanolamine 1.3 parts Monomer mixture Methyl methacrylate 100 parts n-Butyl acrylate 50 parts Styrene 200 parts Ethylene glycol dimethacrylate 100 parts Dropping was completed in 60 minutes. Then, the remaining 23.3 parts of the initiator solution was added, and stirring was continued for 30 minutes to complete the reaction. The particle size of the obtained microgel dispersion of the emulsion was 0.079μ. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 3] Sodium dodecylbenzenesulfonate was placed in a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introducing pipe.
Charge 10 parts and 4000 parts of deionized water and adjust the temperature while stirring.
It was set to 80 ° C. After adding 180 parts of the following initiator solution to this, the dropping of the following monomer mixture was immediately started.

Initiator solution Azobiscyanovaleric acid 10 parts Deionized water 200 parts Dimethylethanolamine 10 parts Monomer mixture Methyl methacrylate 140 parts n-Butyl acrylate 50 parts Styrene 200 parts Ethylene glycol dimethacrylate 100 parts Dropping is completed in 60 minutes After that, the remaining 40 parts of the initiator solution was added, and stirring was continued for 30 minutes to complete the reaction. The aggregate was filtered off with a 400 mesh sieve to obtain an emulsion having a particle diameter of 0.21 μm. This emulsion was ultrafiltered and spray dried to obtain polymer fine particles.

[Production Example 4] 1000 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After 205 parts of the following initiator solution and 50 parts of methyl methacrylate were added thereto, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 130 parts n-Butyl acrylate 50 parts Styrene 200 parts Ethylene glycol dimethacrylate 120 parts After dripping for 120 minutes, stir for 60 minutes Was continued to complete the reaction. The particle size of the resulting microgel dispersion of emulsion was 0.51 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 5] 1000 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After 205 parts of the following initiator solution and 50 parts of methyl methacrylate were added thereto, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 200 parts n-Butyl acrylate 60 parts Styrene 200 parts Ethylene glycol dimethacrylate 40 parts After completion of dropping for 120 minutes, stirring for 60 minutes Was continued to complete the reaction. The particle size of the resulting microgel dispersion of emulsion was 0.53 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 6] 1000 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After 170 parts of the emulsion solution obtained in Production Example 4 and 205 parts of the following initiator solution were added thereto, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 140 parts n-Butyl acrylate 60 parts Styrene 200 parts Ethylene glycol dimethacrylate 100 parts After dropping for 120 minutes, stir for 60 minutes Was continued to complete the reaction. The aggregate was filtered off with a 400 mesh sieve to obtain an emulsion having a particle size of 1.1 μm. The particle size of the microgel dispersion of the emulsion was 1.1 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 7] 1000 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After adding 205 parts of the following initiator solution and 25 parts of methyl methacrylate to this, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture styrene 200 parts n-Butyl acrylate 115 parts Neopentyl glycol dimethacrylate 150 parts Methacrylic acid 10 parts After completion of dropping in 120 minutes, stirring for 60 minutes Was continued to complete the reaction. The particle size of the resulting microgel dispersion of emulsion was 0.53 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 8] 1600 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. To this, 205 parts of the following initiator solution and 50 parts of methyl methacrylate were added, and immediately thereafter, dropwise addition of the following monomer mixture and monomer aqueous solution was simultaneously started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture methacrylic acid methyl 325 parts n-Butyl acrylate 100 parts Neopentyl glycol dimethacrylate 25 parts Monomer aqueous solution N- (3-sulfopropyl)- N-methacryloxyethyl-N, N-dimethylammonium betaine 5 parts Deionized water 200 parts After dropping for 120 minutes, stirring was continued for 60 minutes to complete the reaction. The particle size of the obtained microgel dispersion of emulsion was 0.4 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 9] 1800 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After adding 205 parts of the following initiator solution and 25 parts of methyl methacrylate to this, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 100 parts n-Butyl acrylate 100 parts Styrene 100 parts 2-Ethylhexyl methacrylate 75 parts 2-Hydroxyethyl methacrylate 40 parts Dimethylaminopropyl methacrylamide 10 parts Ethylene glycol dimethacrylate 50 parts After the dropping was completed in 120 minutes, stirring was continued for 60 minutes to complete the reaction. The particle size of the obtained microgel dispersion of emulsion was 0.38 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 10] 1000 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After 205 parts of the following initiator solution and 50 parts of methyl methacrylate were added thereto, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture n-Butyl acrylate 100 parts Styrene 200 parts Ethylene glycol dimethacrylate 75 parts Methacrylic acid 75 parts After dropping for 120 minutes, stir for 60 minutes The reaction was continuously completed. The particle size of the obtained microgel dispersion of emulsion was 0.48 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 11] 1800 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature control device, and a nitrogen introduction tube, and the temperature was raised to 80 ° C while stirring. After 205 parts of the following initiator solution and 50 parts of methyl methacrylate were added thereto, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 200 parts n-Butyl acrylate 100 parts 2-Hydroxyethyl methacrylate 35 parts Meethacrylic acid 15 parts Divinylbenzene 100 parts Addition is completed in 120 minutes. After that, stirring was continued for 60 minutes to complete the reaction. The particle size of the obtained microgel dispersion of emulsion was 0.41 μm. This emulsion was spray-dried to obtain polymer fine particles.

[Production Example 12] 1800 parts of deionized water was charged into a reaction vessel equipped with a stirrer, a cooler, a temperature controller, and a nitrogen introducing tube, and the temperature was raised to 80 ° C while stirring. After adding 205 parts of the following initiator solution and 25 parts of methyl methacrylate to this, the dropping of the following monomer mixture was immediately started.

Initiator solution Ammonium peroxodisulfate 5 parts Deionized water 200 parts Monomer mixture Methyl methacrylate 125 parts n-Butyl acrylate 100 parts Styrene 150 parts Ethylene glycol dimethacrylate 150 parts 2-Sulfoethyl methacrylate 0.5 parts Add dropwise over 120 minutes After the completion of the reaction, stirring was continued for 60 minutes to complete the reaction. The particle size of the resulting microgel dispersion of emulsion was 0.51 μm. This emulsion was spray-dried to obtain polymer fine particles.

Example 1 In a solution in which 10 g of the organic particles obtained in Production Example 4 were uniformly dispersed in 30 g of styrene, 20 g of methyl methacrylate, 10 g of n-butyl acrylate and 40 g of ethylene glycol dimethacrylate, 2,2-azobis (2-methylpropyl nitrile) 1
g was dissolved, and this was added to 900 g of deionized water and Gohsenol GH-17.
(Nippon Gosei Kagaku) 5 g of the solution was added to an aqueous solution with stirring to prepare a suspension.

This was placed in one reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, heated to 80 ° C. for 30 minutes under stirring, and polymerized at this temperature for 6 hours.

The obtained dispersion had a nonvolatile content of 10%, and this was filtered and dried to obtain crosslinkable particles having a particle diameter center of 40 μm. Observation of the particles with an electron microscope revealed that one or more hollows exist inside the particles.

Example 2 A solution of 2,5-azobis (2,4-dimethylvaleronitrile) obtained by uniformly dispersing 15 g of the organic particles obtained in Production Example 2 in 40 g of styrene, 15 g of methyl methacrylate, 15 g of n-butyl acrylate and 30 g of ethylene glycol dimethacrylate was used. ) 1g
Is dissolved in 400 g of deionized water and Gohsenol NH-20 is added.
(Nippon Gosei Kagaku) A suspension was prepared by adding 10 g of an aqueous solution with high speed stirring.

This was placed in a 0.5 liter reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, heated to 60 ° C. for 30 minutes under stirring, and polymerized at this temperature for 6 hours.

The resulting dispersion had a nonvolatile content of 20%, and was filtered and dried to obtain crosslinkable particles having a center of particle diameter of 3 μm. Observation of the cross section of the particles with an electron microscope revealed that there were one or more hollows inside the particles.

Examples 3 to 18 Particles were produced in the same manner as in Example 1 by blending the organic particles shown in Table 1 with the polymerizable monomer, the polymerization catalyst and the dispersant. The obtained particles were confirmed to have hollowness by an electron microscope. It was also found that the hollow ratio and the size of the cavities differ depending on the amount of the initiator, the amount of the monomer having a plurality of αβ unsaturated groups, and the amount of the added particles.

Comparative Example 1 30 g of styrene, 20 g of methyl methacrylate, 10 g of n-butyl acrylate, 40 g of ethylene glycol dimethacrylate and 2,2-azobis (2-methylpropyl nitrile)
Dissolve 1 g, and add this to 900 g deionized water Gohsenol GH-1
A suspension was prepared by adding 0.5 g of 7 (Nippon Gosei Kagaku) to an aqueous solution in which the suspension was stirred while stirring.

This was placed in one reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, heated to 80 ° C. for 30 minutes under stirring, and polymerized at this temperature for 6 hours.

The non-volatile content of the obtained dispersion was 10%, and this was filtered and dried to obtain crosslinkable particles having a center of particle diameter of 30 μm. The particles did not have the hollow as shown in Example 1.

Comparative Example 2 1 g of 2,2-azobis (2,4-dimethylvaleronitrile) was dissolved in 40 g of styrene, 15 g of methyl methacrylate, 15 g of n-butyl acrylate and 30 g of ethylene glycol dimethacrylate, and goshenol NH- was added to 400 g of deionized water. 2
A suspension was prepared by adding 3 g of 0 (Nippon Gosei Kagaku) to an aqueous solution in which it was dissolved with high speed stirring.

This was placed in a 0.5 liter reaction vessel equipped with a stirrer, a cooler, a temperature controller and a nitrogen introducing tube, heated to 60 ° C. for 30 minutes under stirring, and polymerized at this temperature for 6 hours.

The resulting dispersion had a nonvolatile content of 20%, and was filtered and dried to obtain crosslinkable particles having a center of particle diameter of 3 μm. This particle did not have the hollow as shown in Example 2.

Claims (1)

(57) [Claims] 1. A monomer having (a) two or more radically polymerizable ethylenically unsaturated groups in the molecule, (b) a polymerizable monomer other than the monomer (a), c) Organic particles having an average particle diameter of 0.01 to 5 μm, (d) a polymerization initiator, and (e) a dispersant, and the weight ratio of component (a) / component (b) is 0.5 / 99.5 to
60/40, wherein the component (c) is 1 to 50% by weight based on the total weight of the components (a) and (b), obtained by dispersion polymerization in an aqueous medium, and having an average particle diameter of 0.1 to Composite hollow particles in which 300 μm hollow particles and organic particles having an average particle size of 0.01 to 5 μm are combined.