JP2683193B2 - Fine particles, method for producing the same, and electro-optical panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fine particles suitable as a spacer for products having fine layered gaps and a method for producing the same.

[0002]

2. Description of the Related Art In an electro-optical panel such as a liquid crystal light control panel, a liquid crystal display panel, a light control panel or an electrochromic display panel, a light control liquid is sealed between a pair of transparent substrates and the periphery of the transparent substrates is sealed. Seal with adhesive. For example,
In a liquid crystal display panel, in order to keep the thickness of the liquid crystal layer constant and the amount of transmitted light constant, a spacer made of glass fiber chips, silica fine particles, and synthetic resin fine particles is provided between a pair of transparent substrates. Sandwiched.

However, the inner surfaces of the pair of transparent substrates facing each other are not completely flat, and the diameters of the spacers also vary. Therefore, some of the spacers are not sufficiently pressed by the pair of transparent substrates.
Therefore, when the dimming liquid is poured into the gap of the transparent substrate, the spacers are made to flow and move. In addition, in applications such as automobiles that are subject to vibration, the spacers often move in the gap between the transparent substrates and the gap between the pair of electrodes is not constant.

Further, in a liquid crystal display panel, a light control plate for a window, etc., a flexible substrate made of a plastic film is sometimes used, but the spacer is removed due to the deformation of the flexible substrate.

[0005]

Therefore, it has been attempted to provide an adhesive layer on the surface of the spacer and adhere the spacer to the transparent substrate. For example, there is a method in which an adhesive is dissolved in a solvent, fine particles are dispersed in the solution, the dispersion is sprayed on a transparent substrate, the solvent is evaporated, and spacers are scattered. However, in this method, after evaporating the solvent, a large amount of adhesive adheres to the surface of the transparent substrate,
It causes various problems.

Further, there is a method in which fine particles to be spacers are dispersed in an emulsion or solution of a hot-melt type adhesive to deposit the adhesive on the surface of the fine particles (JP-A-1-247154). . In this method, the adhesive is melted in an emulsion or solution and adhered to the surface of the fine particles. Therefore, the melting point of the hot-melt adhesive must be lower than the boiling point of water, which is the medium of the emulsion. .

For this reason, the adhesives adhere to each other in the emulsion, and a large number of fine particles tend to coagulate. Even after it was pulverized, the coagulation and adhesion of fine particles remained so much that it could not be used as a spacer.

An object of the present invention is to provide a spacer that can be adhered and fixed to a transparent substrate, and further, adhesion of an adhesive to the surface of the transparent substrate, condensation of spacers, and adhesion do not occur. To do so.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a granular material comprising a crosslinked polymer compound which is a polymer of a monomer raw material containing 50 to 100 mol% of a polymerizable polyfunctional monomer,
On the surface of the granules, the polymer branches chemically bonded to the cross-linked polymer compound on the surface of the granules, which consist of the polymer of the monofunctional monomer that is the raw material of the hot melt adhesive The present invention relates to fine particles, which are characterized by comprising a polymer of a monofunctional monomer that is a raw material of a hot-melt adhesive that is produced.

The hot melt point of the hot melt adhesive is preferably 100 ° C. or higher and 250 ° C. or lower.

Further, according to the present invention, a raw material containing a polymerizable polyfunctional monomer in an amount of 50 to 100 mol% is polymerized to produce a granular body composed of a crosslinked polymer compound, and at least one of a suspension stabilizer and an emulsifier is prepared. A mixture of a monofunctional monomer, which is a raw material of a hot-melt adhesive, and an oil-soluble polymerization initiator is added to an aqueous dispersion of the granules stabilized by, and the monofunctional monomer is polymerized on the surface of the granules. Thereby, the polymer of the monofunctional monomer and the polymer branch of the monofunctional monomer chemically bonded to the cross-linked polymer compound on the surface of the granule are characterized by being formed on the surface of the granule, The present invention relates to a method for producing fine particles.

According to the present invention, a pair of transparent substrates, electrodes provided on the inner side surfaces of the pair of transparent substrates, a sealing portion for sealing the peripheral edges of the pair of transparent substrates, and a transparent substrate are provided. An electro-optical panel comprising a dimming liquid encapsulated in, and a spacer for keeping a gap between a pair of transparent substrates constant, wherein the above-mentioned fine particles are used as the spacer. The present invention relates to an electro-optical panel that does.

[0013]

The present inventor has reached the present invention as a result of studying a technique for forming a hot-melt type adhesive having a melting point of 100 ° C. or higher on the surface of fine particles. That is, a raw material containing 50 to 100 mol% of a polymerizable polyfunctional monomer is polymerized to produce granules made of a cross-linked polymer material, and hot-melt adhesive is applied to an aqueous suspension or an aqueous emulsion containing the granules. We succeeded in polymerizing the monofunctional monomer on the surface of the granules by adding the monofunctional monomer as the raw material of the agent and the oil-soluble polymerization initiator.

As a result, a polymer branch consisting of a polymer of a monofunctional monomer, which is a raw material of a hot-melt adhesive, is chemically bonded to the cross-linked polymer compound on the surface of the granular material, and on the surface of the granular material. New fine particles composed of the formed polymer of a monofunctional monomer were obtained. This graft bond was formed by the reaction between the unreacted functional groups of the polyfunctional monomer, which is the raw material of the granule, and the monofunctional monomer on the surface of the granule.

By using such fine particles as the spacer of the electro-optical panel, the hot-melt type adhesive on the surface of the spacer can be thermally adhered to the transparent substrate to be fixed. As a result, the spacer does not flow when the dimming liquid is poured into the gap between the pair of transparent substrates, and the spacer does not move in the gap between the transparent substrates due to vibration. Even when a flexible substrate is used, the spacer will not fall off.

Further, since the spacer can be heat-bonded to the transparent substrate, a large amount of adhesive does not adhere to the transparent substrate as in the conventional method. Also, a large number of fine particles are condensed,
The phenomenon of adhesion was not seen at all.

[0017]

The present invention will be described in more detail below. First,
In the first step of the production method of the present invention, a raw material containing a polymerizable polyfunctional monomer is polymerized to produce a granular body made of a crosslinked polymer material. As such a polymerization method, aqueous suspension polymerization or aqueous emulsion polymerization is preferable.

Examples of such polyfunctional monomers include ethylene di (meth) acrylate, propylene di (meth) acrylates, butylene di (meth) acrylates, hexylene di (meth) acrylates, polyethylene glycol di (meth) acrylates, trimethylol propane. Tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol (meth) acrylate, allyl (meth) acrylate Acrylate, methallyl (meth) acrylate, triarylyl (iso) cyanurate, triarylyl trimerite, divinylbenzene,
Examples include di (meth) allyl phthalate, di (meth) acryloyloxyethyl phthalate, vinylphenyl (meth) allyl ether, and di (meth) allyl acrylamide.

A monofunctional monomer copolymerizable with the above polyfunctional monomer may be added to the raw material of the crosslinked polymer material. Examples of this are methyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth).
Examples thereof include acrylate, styrene, vinyltoluene, α-methylstyrene, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, maleic acid, fumaric acid, (meth) acrylic acid and itaconic acid.

The molar ratio of the polyfunctional monomer to the monofunctional monomer in the above raw materials is 100 mol% in total.
Then, the ratio of the polyfunctional monomer is 50 mol to 100.
Although it is set to mol%, it is more preferably set to 70 to 100 mol%. When the ratio of the polyfunctional monomer is increased in this way, unreacted polymerizable reactive groups that do not participate in the polymerization remain due to the steric hindrance of the atomic group of the polyfunctional monomer, and remain on the surface of the granular material. In the next step, this serves as a bonding point for graft copolymerization with the monofunctional monomer that is a raw material of the hot melt adhesive, and the graft copolymerization is promoted.

One or more suspension stabilizers can be used in the aqueous suspension polymerization to produce the granulate. Examples thereof include polyvinyl alcohol, partially saponified polyvinyl alcohol, poly (meth) acrylate, polyacrylamide, partially saponified polyacrylamide, water-soluble polymers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, calcium phosphates, calcium carbonate, etc. Inorganic salt powder, etc.

One or more emulsifiers are used in the aqueous emulsion polymerization to produce the granulate. Examples thereof include higher fatty acid salts such as sodium laurate and sodium oleate, alkyl sulfates such as sodium lauryl sulfate, and anionic surfactants such as alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate. Also,
Polyethylene glycol alkyl phenyl ethers such as octaethylene glycol nonyl phenyl ether,
There are nonionic surfactants such as polyethylene glycol monoalkyl ethers such as hexadeca ethylene glycol lauryl ether. Of course, the above-mentioned suspension stabilizer and emulsion stabilizer may be used as a mixture.

As the polymerization initiator in the step of producing the granular material, it is preferable that the polymerization initiation radical species after decomposition is oil-soluble. Examples of the polymerization initiator include peroxides such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, and methyl ethyl ketone peroxide.

These organic peroxides include amines such as dimethylaniline, triethanolamine and triethyleneglycoldiamine, sodium sulfite, sodium hyposulfite,
A redox polymerization initiation system with a reducing substance such as acetaldehyde, glucose or ascorbic acid may be combined. In this case, transition metal ions such as iron, nickel, cobalt, and copper may or may not be interposed.

In the emulsion polymerization system, potassium persulfate, hydrogen peroxide, etc. may be used in addition to the above oil-soluble polymerization initiator.

In the present invention, a monofunctional monomer and an oil-soluble polymerization initiator, which are raw materials for a hot-melt adhesive, are added to an aqueous suspension or an aqueous emulsion containing the above-mentioned particulates. At this time, there are two modes.

In the first embodiment, after the above-mentioned aqueous suspension polymerization or aqueous emulsion polymerization is completed, a monofunctional monomer and an oil-soluble polymerization initiator are added to this reaction solution.
And when manufacturing fine particles for spacers,
The particle system of fine particles is required to be uniform. Therefore, the fine particles are classified after the hot melt adhesive is generated.

In the second embodiment, the particles are once taken out after the above-mentioned aqueous suspension polymerization or aqueous emulsion polymerization is completed. This granular material is again charged into an aqueous suspension or an aqueous emulsion, and a monofunctional monomer and an oil-soluble polymerization initiator are added thereto. The aqueous suspension in this embodiment may contain the above-mentioned suspension stabilizer. The aqueous emulsion in this embodiment may contain the above-mentioned emulsifier, suspension stabilizer and emulsion stabilizer.

In the case of producing fine particles for use as a spacer in the second embodiment, the particles are once taken out of the reaction system and then classified. Then, the classified granules are mixed with water, an emulsifier, an emulsion stabilizer, a suspension stabilizer, etc.,
An aqueous suspension or aqueous emulsion containing granules is obtained.

As the monofunctional monomer which is a raw material of the hot melt adhesive, methyl methacrylate, t-butyl methacrylate, cyclohexyl (meth) acrylate,
Phenyl (meth) acrylate, acrylonitrile, styrene, α-methylstyrene, vinyltoluene, (meth)
One or more monofunctional monomers such as acrylic acid, itaconic acid, maleic acid, fumaric acid and the like, whose homopolymers have a relatively high glass transition point, can be used.

Further, a monofunctional monomer having a low homopolymer glass transition point can be used in combination with the above monofunctional monomer. Examples thereof include methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and octyl (meth) acrylate.

In selecting these monofunctional monomers, the glass transition point of the hot-melt type adhesive produced is set to 60.
It is preferably in the range of ℃ to 250 ℃. The hot melt point of the adhesive is preferably in the range of 100 ° C to 250 ° C, more preferably 120 ° C to 200 ° C. By setting the hot melt point to 100 ° C. or higher, it becomes difficult for the fine particles to adhere to each other and aggregate at the synthesis stage. By setting the hot melt point to 250 ° C. or lower, it becomes easy to thermally bond the transparent substrate to the fine particles at the stage of assembling the electro-optical panel.

When the above-mentioned monofunctional monomer and oil-soluble polymerization initiator are added, the monofunctional monomer and the oil-soluble polymerization initiator are added to a heated aqueous suspension or aqueous emulsion containing particles. The mixture is added all at once or gradually. Also,
The oil-soluble polymerization initiator may be added first, and then the monofunctional monomer may be added.

As the oil-soluble polymerization initiator at the stage of this graft polymerization, the above-mentioned organic peroxide or a redox polymerization initiation system of an organic peroxide and a reducing substance is preferable.

The particles made of the crosslinked polymer material are hydrophobic, and the monofunctional monomer for the adhesive is also hydrophobic. When the monofunctional monomer is added to the aqueous suspension or the aqueous emulsion containing the particles, the monofunctional monomer migrates to the surface of the particles, where it is graft-polymerized to produce a hot melt adhesive.

When the amount of the monofunctional monomer for the adhesive is small, the polymerization proceeds on a part of the surface of the granule, so that the adhesive polymer partially graft-polymerizes and adheres on the surface of the granule. , Fine particles such as Kompei sugar are produced. When the amount of the monofunctional monomer is large, the surface of the granular material is covered with the coating film made of the hot melt adhesive. The surface of this coating may be smooth or may have irregularities.

If the weight of the granules is 100 parts by weight, and the weight of the hot melt adhesive is 100 to 200 parts by weight,
The adhesive strength is very high. Further, in the case of a liquid crystal display panel, the fine particles are thermally adhered to a polymer alignment film such as polyimide. However, when the amount of the adhesive is large, there is a problem that the adhesive flows during hot melt and the alignment film is soiled. Came out. In this case, when the weight of the granular material is 100 parts by weight, the amount of the hot melt adhesive is preferably 2 to 100 parts by weight, more preferably 5 to 50 parts by weight.

In the above-mentioned first embodiment, the suspension stabilizer or emulsion stabilizer in the aqueous suspension or emulsion can be partially removed by filtration or decantation, or all of them can be removed, Other suspension stabilizers and emulsion stabilizers can be added. In the second aspect,
A suspension stabilizer or an emulsion stabilizer can be newly added to prevent aggregation of the particles or grafting of the polymerization system during the graft polymerization.

It should be noted here that when the amount of the suspension stabilizer or the emulsion stabilizer in the graft polymerization step is too large, the monofunctional monomer for the adhesive does not migrate to the surface of the granules, but is left alone. It is easy to form a suspension system or an emulsion system. In this case, the adhesive does not adhere to the surface of the granular material.

The monofunctional monomer as the raw material of the hot melt adhesive in the present invention is preferably 100% graft-polymerized on the granules, but even if the grafting efficiency is almost 0%, it is adhered by physical adsorption. Functions can be fulfilled. When the grafting efficiency is 5% or more, a strong adhesive force can be obtained.

After the hot melt type adhesive is produced, the fine particles are washed with water to remove the suspension stabilizer, the emulsifier, the decomposition product of the polymerization initiator and other impurities, and the fine particles are dried.

The fine particles of the present invention can be directly sprayed on the surface of a transparent substrate in a dry state, can be sprayed while blowing nitrogen or air, or can be sprayed by an electrostatic spraying method. In a state where the fine particles are dispersed in a water / alcohol medium or a chlorofluorocarbon / alcohol medium, the dispersion may be sprayed to dry the medium. When the amount of spray is 10 to 300 pieces / mm ² , the effect as a spacer is sufficiently obtained and there is no problem in appearance.

Examples of the material of the transparent substrate include glass, polyethylene terephthalate film, polycarbonate film, other transparent films made of synthetic resin, single crystal silicon, polycrystalline silicon and the like. On the surface of the transparent substrate, a patterned transparent electrode, a liquid crystal alignment film, a color filter, an antireflection film, a deflection film, a retardation film, a reflection film, an insulating film and the like may be formed.

After the fine particles are sprayed on one transparent substrate and before or after the other transparent substrate is superposed thereon, the hot melt adhesive is melted by heating preferably to 100 to 250 ° C. and applying pressure. Let After assembling the panel, the dimming liquid is poured into the gap. As the dimming liquid, there are a liquid crystal and an electrochromic material.

A light control panel can be manufactured by using a glass plate or a transparent plastic film as the transparent substrate. This is for a window glass and is a panel in which a ground glass tone and a transparent glass tone can be selected by switching the voltage applied to the electrodes. On the surface of the transparent substrate, a transparent electrode that is not subjected to patterning is formed, the fine particles of the present invention are sprayed on one transparent substrate, and the other transparent substrate is heated and pressed in accordance with this, and the transparent substrates are bonded to each other. . Next, the periphery of the gap of the transparent substrate is sealed,
A photopolymerization initiator and a liquid crystal are sealed in a gap, and ultraviolet rays are irradiated to cure and deposit a photosensitive resin to produce a polymer network liquid crystal light control panel.

Hereinafter, more specific experimental results will be described. (Experiment 1) In a separable flask having a volume of 1 liter, 5
600 ml of water containing polyvinyl alcohol by weight,
A uniform mixture of 100 g of divinylbenzene, 100 g of dipentaerythritol hexaacrylate and 3 g of benzoyl peroxide was added. This aqueous suspension was heated to 80 ° C. with stirring under a nitrogen atmosphere and suspension polymerized for 8 hours. Then water is removed from the suspension by decantation,
It was washed with water until an aqueous solution having a polyvinyl alcohol ratio of about 0.2% was obtained to obtain a suspension having a solid content of 25% by weight.

The aqueous suspension thus obtained was subjected to a second stage graft polymerization reaction while stirring at 80 ° C. under a nitrogen atmosphere. That is, a uniform mixture of 40 g of styrene, 4 g of acrylic acid and 0.8 g of benzoyl peroxide was added dropwise to the above aqueous suspension over 1 hour, and then at 80 ° C for 4 hours and at 85 ° C for 5 hours.
Polymerization was carried out for a time to obtain fine particles having a graft efficiency of 15%.

The fine particles were classified to have an average particle size of 7.2 μm,
Fine particles with a standard deviation of particle size of 0.32 μm were obtained. A glass substrate having a transparent electrode and an alignment film was rubbed with absorbent cotton for alignment treatment, and the fine particles having an average particle size of 7.2 μm were sprayed by an air blow. The periphery of this glass substrate is coated with a strip of epoxy resin mixed with glass fiber chips with an average particle size of 7.0 μm, and the other glass substrate is covered.
Overlaid. At this time, the transparent electrodes of the pair of glass substrates were opposed to each other with a gap between the glass substrates interposed therebetween. In addition, the epoxy resin band-shaped coating film was provided with an opening at one location, and this opening was used as a liquid crystal injection port.

In this state, 0.5 kg / cm ² at 160 ° C. for 3 hours
Heat treatment was applied while applying the surface pressure of (1) to cure the epoxy resin, and at the same time, the adhesive on the surface of the fine particles was melted and adhered and fixed to the glass substrate. Next, when liquid crystal was injected into the gap of the transparent substrate, the fine particles in the gap hardly moved in the position. Then, the liquid crystal inlet was sealed. Finally, a polarizing film having a polarizing function in the same direction as the molecular alignment of the liquid crystal was attached to the outer surface of one glass substrate to manufacture a liquid crystal display panel.

No condensation or coarsening was observed in the fine particles in this experimental example. Further, even when vibration was applied to the liquid crystal display panel, the fine particles did not move in the gap.

(Experiment 2) A liquid crystal display panel was manufactured in the same manner as in Experiment 1. However, in the suspension polymerization process for synthesizing the fine particles, 600 m of water containing 5% by weight of polyvinyl alcohol is placed in a separable flask having a capacity of 1 liter.
l and 150 g of pentaerythritol tetraacrylate
And tetraethylene glycol dimethacrylate 50g
And a homogeneous mixture of 3 g of benzoyl peroxide was added.

In the second stage graft polymerization reaction, 20 g of methyl methacrylate and 1.5 g of methacrylic acid were used.
Was used as the monofunctional monomer. As the polymerization initiator,
A redox polymerization initiator system was used which contained 0.4 g of cumene hydroperoxide and 0.03 g of ferrous sulfate and 1 g of glucose in the aqueous phase. The graft polymerization reaction was carried out at 70 ° C.

As a result, the efficiency of grafting on the surface of the granular material
Fine particles with 20% methacrylic resin adhesive were obtained. This was classified to obtain spacer particles having an average particle size of 6.0 μm, and a liquid crystal display panel was manufactured in the same manner as in Experiment 1.

(Experiment 3) In a separable flask having a capacity of 1 liter, 600 ml of water containing 5% by weight of polyvinyl alcohol, 100 g of divinylbenzene, 100 g of dipentaerythritol hexaacrylate and 3 g of benzoyl peroxide were uniformly mixed. Liquid was added. This aqueous suspension was heated to 80 ° C. with stirring under a nitrogen atmosphere and suspension polymerized for 8 hours. Then, the granules are washed with water, classified, and the average particle size is 6.0 μ
Granules with m 2 and standard deviation 0.24 μm were obtained.

The classified particles were dispersed in 300 ml of an aqueous solution containing 0.1% by weight of polyvinyl alcohol and 0.05% by weight of polyethylene glycol lauryl ether to obtain an aqueous suspension. Glucose 1 was added to this aqueous suspension.
g and ferrous sulfate 0.02 g were added, and the mixture was heated to 70 ° C. in a nitrogen atmosphere. A mixed solution of 10 g of styrene, 1 g of acrylic acid and 0.2 g of cumene hydroperoxide was gradually added dropwise to the aqueous emulsion over 30 minutes to polymerize on the surface of the granular material. Thus, fine particles having an adhesive with a graft efficiency of 12% were obtained.

Using these fine particles, a liquid crystal display panel was manufactured in the same manner as in Example 1.

[0057]

As described above, according to the present invention, a monofunctional monomer as a raw material of a hot-melt adhesive is polymerized on the surface of a granular body composed of a crosslinked polymer compound, and a monofunctional monomer polymer is obtained. A new fine particle was obtained in which the part was graft-bonded to the crosslinked polymer compound on the surface of the granular material. This graft bond was formed by the reaction of the unreacted functional groups of the polyfunctional monomer, which is the raw material of the granule, with the single crystal monomer on the surface of the granule.

By using such fine particles as the spacer of the electro-optical panel, the hot-melt type adhesive on the surface of the spacer can be thermally adhered and fixed to the transparent substrate. As a result, the spacer does not flow when the dimming liquid is poured into the gap between the pair of transparent substrates, and the spacer does not move in the gap between the transparent substrates due to vibration. Even when a flexible substrate is used, the spacer will not fall off.

Further, since the spacer can be heat-bonded to the transparent substrate, a large amount of adhesive does not adhere to the transparent substrate unlike the conventional method. Also, a large number of fine particles are condensed,
The phenomenon of adhesion was not seen at all.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09J 201/00 C09J 201/00 // G02F 1/1339 500 G02F 1/1339 500

Claims (5)

(57) [Claims] 1. A polymerizable polyfunctional monomer is added in an amount of 50 to 100.
a granule comprising a crosslinked polymer compound which is a polymer of a monomer raw material containing mol%, and a polymer branch chemically bonded to the crosslinked polymer compound on the surface of the granule,
A polymer branch made of a polymer of a monofunctional monomer which is a raw material of a hot melt adhesive and a weight of the monofunctional monomer which is a raw material of the hot melt adhesive, which is formed on the surface of the granular material. Fine particles, characterized by comprising a coalesce. 2. The fine particles according to claim 1, wherein the hot-melt adhesive has a hot-melt point of 100 ° C. or higher and 250 ° C. or lower. 3. A pair of transparent substrates, electrodes respectively provided on the inner side surfaces of the pair of transparent substrates, a sealing portion for sealing the peripheral edges of the pair of transparent substrates, and a space between the transparent substrates. An electro-optical panel comprising a dimmering liquid and a spacer for keeping a gap between a pair of transparent substrates constant, wherein the fine particles according to claim 1 are used as the spacer. Electro-optical panel. 4. A polymerizable polyfunctional monomer is added in an amount of 50 to 100.
A monomer raw material containing mol% is polymerized to produce a granule made of a cross-linked polymer compound, and hot melt is added to an aqueous dispersion liquid of the granule stabilized by at least one of a suspension stabilizer and an emulsifier. Add a mixture of a monofunctional monomer and an oil-soluble polymerization initiator, which are raw materials for the mold adhesive,
By polymerizing the monofunctional monomer on the surface of the granular material, a polymer of the monofunctional monomer and a polymer of the monofunctional monomer chemically bonded to the crosslinked polymer compound on the surface of the granular material. A method for producing fine particles, characterized in that branches are formed on the surface of the granular body. 5. The method for producing fine particles according to claim 4, wherein the particulate material is produced by subjecting the monomer raw material to aqueous suspension polymerization or aqueous emulsion polymerization.