JP2013054130A - Method for manufacturing resin fine particles and the resin fine particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing resin fine particles allowing manufacture of resin fine particles of high charge amount with high yield, and the resin fine particles obtained therewith.SOLUTION: The method is for manufacturing resin fine particles included in a display particle usable for an information display panel. The display particle is obtained by attaching resin fine particles on a surface of a matrix particle. The display particles are encapsulated between two opposing substrates. At least one of the substrates is transparent. An electrical field is applied between the substrates to cause the display particles move so that image information is displayed in the information display panel. The method includes: a preliminary polymerization step for polymerizing a polymerizable monomer having one polymerizable functional group in a molecule to form a particle nucleus; and a main polymerization step for adding and polymerizing a polymerization component including a cross-linkable monomer having at least two or more vinyl groups in a molecule, in this order. The proportion of the cross-linkable monomer to a sum total of the polymerizable monomer and the cross-linkable monomer in the preliminary polymerization step and in the main polymerization step is 20 mol% or larger.

Description

  The present invention relates to a resin fine particle constituting composite display particles used in an information display panel for displaying information such as images by moving display particles sealed between two opposing substrates at least one of which is transparent. The present invention relates to a production method and resin fine particles produced using the production method.

  A liquid crystal display (LCD) is widely used as an information display device. However, it is generally known that liquid crystal display devices have drawbacks such as large power consumption and narrow viewing angle. Therefore, as an alternative to the liquid crystal display device, a plurality of cells partitioned by a partition are formed between two substrates (for example, glass substrates) at least one of which is transparent, and display particles configured as a particle group in the cells. There is a proposal for an information display panel that displays information such as an image by moving the display particles and enclosing the particles (see, for example, Patent Document 1).

  The information display panel as described above displays information such as an intended image by electrically moving display particles between substrates according to information such as an image. Here, the particle group (display particles) repeatedly moves in the space between the substrates in accordance with the information requested to be displayed. Accordingly, there is a demand for homogeneous and durable display particles that constitute a particle group as display particles.

  Therefore, other fine particles were added to the large particles that serve as the base of the display particles, with the intention of improving the durability of the display particles when the electrical properties were stabilized and the display was repeatedly rewritten. A technique relating to so-called composite particles has been proposed (see, for example, Patent Document 2). This technique discloses a composite display particle in which a child particle is added to the surface of a mother particle, and an information display panel using the same. By adopting a form in which child particles having a predetermined condition are added to the mother particles, it is possible to improve durability when the display particles are repeatedly moved for display rewriting.

International Publication No. 2003/050606 Pamphlet JP 2006-72283 A

  In order to maintain the adhesion of the display particles to the substrate for a long period, display particles having a high adhesion force, that is, a high charge amount are required. However, when a large amount of crosslinkable monomer is added in order to obtain a high charge amount of child particles, a large amount of agglomerates are formed, and the yield is significantly adversely affected.

  An object of the present invention is to provide a resin fine particle production method for producing resin fine particles having a high charge amount in a high yield, and resin fine particles obtained thereby.

The present inventors solve the above-mentioned problem by sequentially performing a pre-polymerization step in which a polymerizable monomer is polymerized to form particle nuclei and a main polymerization step in which a polymerization component containing a cross-linkable monomer is added and polymerized. I found out that I could do it.
That is, the present invention provides the following [1] to [8].
[1] Display particles formed by fixing resin fine particles on the surface of mother particles are sealed between two opposing substrates, at least one of which is transparent, and an electric field is applied between the substrates, whereby the display particles are formed. A method for producing resin fine particles constituting the display particles used in an information display panel for displaying image information by moving the image display panel,
Polymerization is performed by adding a prepolymerization step in which a polymerizable monomer having one polymerizable functional group in a molecule is polymerized to form particle nuclei and a polymerization component containing a crosslinkable monomer having two or more vinyl groups in the molecule. The main polymerization step is performed in this order,
A method for producing resin fine particles, wherein the ratio of the crosslinkable monomer to the total of the polymerizable monomer and the crosslinkable monomer in the preliminary polymerization step and the main polymerization step is 25% by mass or more.
[2] The method for producing resin fine particles according to [1], wherein the polymerization component in the main polymerization step further includes a polymerizable monomer having one polymerizable functional group in the molecule.
[3] The method for producing resin fine particles according to [2], wherein the ratio of the crosslinkable monomer to the total of the polymerizable monomer and the crosslinkable monomer in the main polymerization step is 25 to 90% by mass.
[4] The method for producing resin fine particles according to any one of [1] to [3], wherein the polymerization component is added a plurality of times in the main polymerization step.
[5] Any of [1] to [4], wherein the crosslinkable monomer having two or more vinyl groups in the molecule is at least one selected from divinylbenzene, divinylnaphthalene, divinylbiphenyl, and ethylene glycol dimethacrylate. The manufacturing method of the resin microparticles | fine-particles of description.
[6] The method for producing resin fine particles according to any one of [1] to [5], wherein the polymerizable monomer having one polymerizable functional group in the molecule is a monomer having one vinyl group.
[7] The method for producing resin fine particles according to any one of [1] to [6], wherein the preliminary polymerization step and the main polymerization step are performed by an emulsion polymerization method.
[8] Display particles obtained by fixing resin fine particles to the surface of the mother particles are sealed between two opposing substrates, at least one of which is transparent, and an electric field is applied between the substrates to thereby form the display particles. Resin fine particles constituting the display particles used in an information display panel that moves and displays image information,
Resin fine particles produced using the method for producing resin fine particles according to any one of [1] to [7].

  According to the present invention, resin particles having a high charge amount can be produced in a high yield.

It is a schematic diagram for demonstrating an example of the display particle comprised using the resin microparticles | fine-particles obtained by this invention. (A), (b) is an expanded sectional view which shows an example of the information display panel, respectively. (A), (b) is an expanded sectional view which shows another example of the information display panel, respectively.

  In order to facilitate understanding of the present invention, first, an outline of display particles using the resin fine particles (child particles) according to the present invention will be described, and then the resin fine particles and the manufacturing method thereof according to the present invention will be described. Then, details of the display particles and an information display panel using the display particles will be described.

<Overview of display particles>
FIG. 1 is a schematic view showing an example of composite display particles constituted by using resin fine particles according to the present invention to be described later.

In FIG. 1, display particles 31 are formed by fixing resin fine particles 33 according to the present embodiment on the surfaces of base particles 32. That is, the composite fine particles 31 are configured by fixing the resin fine particles 33 to the surface of the base particles 32.
Here, the “adhesion” means that the resin fine particles 33 do not move when the display is rewritten repeatedly because the resin fine particles 33 are embedded in the surface of the mother particles 32 and fixed by adhesion, adhesion, or the like. means.

<Resin fine particles and production method thereof>
Next, the resin fine particles and the manufacturing method thereof according to the present invention will be described.
The present inventors added a prepolymerization step for polymerizing a polymerizable monomer to form particle nuclei and a polymerization component containing a crosslinkable monomer even when a large amount of a crosslinkable monomer is used as a raw material polymerization component. The present inventors have found that high-charge resin fine particles can be obtained in a high yield by sequentially performing the main polymerization step for polymerization.
That is, in the method for producing resin fine particles according to the present embodiment, display particles formed by fixing resin fine particles to the surface of a mother particle are sealed between two opposing substrates at least one of which is transparent, A method for producing resin fine particles constituting the display particles used in an information display panel for displaying image information by moving the display particles by applying an electric field to
Polymerization is performed by adding a prepolymerization step in which a polymerizable monomer having one polymerizable functional group in a molecule is polymerized to form particle nuclei and a polymerization component containing a crosslinkable monomer having two or more vinyl groups in the molecule. The main polymerization step is performed in this order,
The ratio of the crosslinkable monomer to the total of the polymerizable monomer and the crosslinkable monomer in the preliminary polymerization step and the main polymerization step is 25% by mass or more.
The method for producing the resin fine particles will be described in detail below.

In the method for producing resin fine particles according to the present invention, first, a prepolymerization step of polymerizing a polymerizable monomer having one polymerizable functional group in a molecule to form particle nuclei, and two vinyl groups in the molecule. The main polymerization step of adding and polymerizing the polymerization component containing the crosslinkable monomer as described above is performed in this order.
The monomer used in the preliminary polymerization step is preferably only a polymerizable monomer.
The polymerization component in the main polymerization step preferably further contains a polymerizable monomer having one polymerizable functional group in the molecule, and this polymerizable monomer is the same as that used in the above-mentioned prepolymerization step. In the main polymerization step, the polymerization components can be added all at once or a plurality of times. However, if the addition is performed a plurality of times, the concentration of the crosslinkable monomer can be easily maintained, so that the agglomerates From the viewpoint of suppressing the generation of. The addition of the polymerization component in the main polymerization step is preferably performed by dividing into 2 to 6 times, and more preferably performed by dividing into 3 to 4 times.
Moreover, it is preferable to control the polymerization component added at each time so as to contain a crosslinkable monomer at a concentration equal to or higher than that of the polymerization component added immediately before.

  Moreover, the ratio of the crosslinkable monomer with respect to the sum total of the polymerizable monomer and the crosslinkable monomer in the prepolymerization step and the main polymerization step in the method for producing resin fine particles of the present invention is 25% by mass or more. By setting the content of the crosslinkable monomer in the above range, the hardness of the resin fine particles can be sufficiently increased, and the amount of unreacted vinyl groups in the resin fine particles can be set in a desired range. The proportion of the crosslinkable monomer is preferably 25% by mass or more and 90% by mass or less, and more preferably 30% by mass or more and 70% by mass or less.

The resin fine particles preferably include one or more cross-linked resins selected from a cross-linked olefin resin, a cross-linked styrene resin, a cross-linked acrylic resin, a cross-linked urethane resin, and a cross-linked epoxy resin. By including these cross-linked resins, the hardness of the resin fine particles can be sufficiently increased, and by including these cross-linked resins, it is possible to obtain chargeable resin fine particles having excellent chargeability and charge stability. it can.
More preferably, the crosslinked resin contains a crosslinked styrene resin or a crosslinked acrylic resin.

  Examples of the polymerizable monomer having one polymerizable functional group in the molecule include styrene monomers such as styrene, α-methylstyrene, and α-chlorostyrene; methyl acrylate, ethyl acrylate, butyl acrylate, and cyclohexyl acrylate. Acrylic monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and methacrylic monomers such as cyclohexyl methacrylate; cycloolefin monomers such as vinylcyclohexane; and vinyl groups such as vinylnaphthalene and 4-vinylphenyl. And the like. These may be used alone or in combination of two or more.

  As the crosslinkable monomer (crosslinking agent), a compound having two or more vinyl groups in the molecule is used from the viewpoint of the strength of the resin fine particles. Examples of the crosslinkable monomer include divinylbenzene, divinylnaphthalene, divinylbiphenyl, and ethylene glycol dimethacrylate. These may be used alone or in combination of two or more.

The prepolymerization step and the main polymerization step can be performed according to an emulsion polymerization method, a non-aqueous dispersion polymerization method, or the like. Specifically, the emulsion polymerization method is appropriately selected using an emulsifier having a surfactant effect. The reaction can be performed in a solvent in the presence of a polymerization initiator. The solvent used for the polymerization is not particularly limited, and a solvent used in an ordinary emulsion polymerization method can be used, and examples thereof include purified water and a mixed liquid of an arbitrary ratio of purified water and methanol.
In the non-aqueous dispersion polymerization method, a solution in which the monomer, polymerization initiator and dispersion stabilizer are dissolved in a suitable solvent is placed at a predetermined temperature to polymerize the monomer. The obtained polymerization solution is filtered, washed with an appropriately selected solvent, and then fine particles are collected by a centrifugal separator or the like and dried in an oven or the like at a predetermined temperature to obtain resin fine particles.

  The emulsion polymerization employed in the production of the resin fine particles may be carried out in the same manner as used in the conventional production of particles, and an emulsifier may or may not be used depending on circumstances. When an emulsifier is used, for example, linear and branched such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, ammonium myristyl sulfate, sodium cetyl sulfate, ammonium cetyl sulfate, sodium stearyl sulfate, ammonium stearyl sulfate, sodium oleyl sulfate, ammonium oleyl sulfate Alkyl sulfate ester salt; sodium lauryl sulfonate, ammonium lauryl sulfonate, sodium myristyl sulfonate, ammonium myristyl sulfonate, sodium cetyl sulfonate, ammonium cetyl sulfonate, sodium stearyl sulfonate, ammonium stearyl sulfonate, sodium oleyl sulfonate, Linear and branched alkanes such as ammonium oleyl sulfonate Α-olefin sulfonates such as sodium α-olefin sulfonate and ammonium α-olefin sulfonate; nonylphenol sulfate sodium salt, nonylphenol sulfate ammonium salt, dodecylphenol sulfate sodium salt (lauryl sulfate sodium salt) ), Alkylphenol sulfates such as ammonium dodecylphenol sulfate (ammonium lauryl sulfate); alkylbenzenes such as sodium dodecylbenzenesulfonate (sodium laurylbenzenesulfonate), ammonium dodecylbenzenesulfonate (ammonium laurylbenzenesulfonate) Sulfonate: Sodium butyl naphthalene sulfonate, Butyl naphthalene sulfone Alkyl naphthalene sulfonates such as ammonium; alkyl sulfosuccinates such as sodium dioctyl sulfosuccinate and sodium monooctyl sulfosuccinate; sodium dodecyl diphenyl ether disulfonate (sodium lauryl diphenyl ether disulfonate), ammonium dodecyl diphenyl ether disulfonate (ammonium lauryl diphenyl ether disulfonate) ) Alkyl diphenyl ether disulfonates such as naphthalenesulfonic acid formalin condensate salts, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether ammonium sulfate, polyoxyethylene myristyl ether sodium sulfate, polyoxyethylene myristyl ether ammonium sulfate, polyoxyethylene Polyoxyethylene alkyl ethers such as sodium polyethylene cetyl ether sulfate, ammonium polyoxyethylene cetyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, ammonium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, ammonium polyoxyethylene oleyl ether sulfate Sulfate ester salt; polyoxyethylene nonylphenyl ether sulfate sodium salt, polyoxyethylene nonylphenyl ether sulfate ammonium salt and other polyoxyethylene alkylphenyl ether sulfate salts; polyoxyethylene-polyoxypropylene block copolymer sulfuric acid Ester sodium salt, polyoxyethylene-polyoxybuty Sulfate ester salt of polyoxyethylene-polyoxyalkylene block copolymer such as sulfuric acid ester sodium salt of polyblock copolymer; sulfate ester sodium salt of polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene-polyoxypropylene block copolymer Examples include sulfuric acid ester salts of alkyl ethers of polyoxyethylene-polyoxyalkylene block copolymers, such as sulfuric acid sodium salt of dodecyl ether of ethylene-polyoxybutylene block copolymers. A combination of the above may also be used.

Examples of the polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; hydrogen peroxide solution, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, 3, 5, 5-trimethylhexanoyl peroxide, di-t-butyl peroxide, t-butylperoxy-2-ethylbutanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxypivalate, Organic peroxides such as diisopropyl peroxydicarbonate, di-t-butylperoxyisophthalate, and t-butylperoxyisobutyrate; 2,2′-azobis [2- (trifluoromethylsulfonic acid-2- Methylimidazolin-2-yl)] propane, 2,2′-azobis [2- (2-methylimidazole) Rin-2-yl)] propane hydrochloride, 2,2′-azobis [2- (2-methylimidazolin-2-yl)] propane sulfate, 2,2′-azobis (1-imino-1-pyrrolidino- 2-methylpropane) hydrochloride, 2,2′-azobis [2- (trifluoromethylbenzenesulfonic acid-2-methylimidazolin-2-yl) propane, 2,2′-azobis [2- (toluenesulfonic acid- Azo initiators having an imidazoline group such as 2-methylimidazolin-2-yl) propane, 2,2′-azobis [2- (benzenesulfonic acid-2-methylimidazolin-2-yl) propane; Azo initiators having a pyridine group such as azobis [4-cyanovaleric acid (methylpyridine) amide]; 4,4′-azobis [4-cyanovaleric acid (methylamine) amide], 4, '-Azobis [4-cyanovaleric acid (methylcyclohexylamine) amide], 2,2-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2'-azobis (2-amidinopropane) An azo initiator having an amino group such as dihydrochloride; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisiso Other azo initiators such as butyronitrile may be mentioned, and these may be used alone or in combination of two or more.
Among these, an azo initiator is preferable because of its high reactivity under emulsion polymerization, and an azo compound having a hydroxyl group at the terminal is more preferable because of the need to reduce the influence on chargeability. Moreover, as the usage-amount of the said polymerization initiator, it is preferable to use in 0.03-5 mass% with respect to the monomer amount. The polymerization initiator may be added all at once at the beginning of the polymerization or may be added during the polymerization.

  Examples of the dispersion stabilizer include methyl cellulose, ethyl cellulose, sodium di (2-ethylhexyl) sulfosuccinate, polyvinyl alcohol, polyoxyethylene polyoxypropylene copolymer, polyoxyethylene polyisoprene copolymer, polyvinyl ether, polyacrylamide. , Polycyclohexane, polytricyclodecyl methacrylate, poly-4-methylpentene-1, cycloolefin polymer, ethylene-cycloolefin copolymer and the like. Cycloolefin polymers include norbornene, norbornadiene, methylnorbornene, dimethylnorbornene, ethylnorbornene, chloronorbornene, chloromethylnorbornene, cyclohexylnorbornene, dicyclohexylnorbornene, phenylnorbornene, diphenylnorbornene, pyridinylnorbornene, dicyclopentadiene and alkyl thereof. Alternatively, an aryl substituent, tricyclopentadiene and its alkyl or aryl substituent, tetracyclododecene and its alkyl or aryl substituent, and the like can be mentioned.

The preliminary polymerization step is preferably carried out until the polymerization conversion rate of the polymerizable monomer reaches 10 to 100% by mass, and at least a part of the polymerization component is added to perform the main polymerization step. When the polymerization conversion rate is within this range, it is possible to reduce the formation of aggregates and reduce the amount of unpolymerized components after the polymerization reaction. From this viewpoint, the polymerization conversion rate is more preferably 30 to 100% by mass, and further preferably 50 to 100% by mass. The polymerization conversion rate means the polymerization conversion rate of the polymerizable monomer added in the preliminary polymerization step.
This polymerization conversion rate can be controlled to a predetermined value by changing the reaction time of the polymerization reaction.
For example, as a preliminary experiment, a plurality of polymerization reactions are carried out at a predetermined polymerization temperature for a polymerization component having a predetermined composition while varying only the reaction time, and the polymerization conversion rate is measured. Based on the relationship between the reaction time and the polymerization conversion rate obtained in this preliminary experiment, the reaction time required to obtain the predetermined polymerization conversion rate can be derived.

  The polymerization temperature in the polymerization is preferably 50 ° C. or higher, more preferably 60 to 110 ° C. The polymerization reaction time can be set according to the target polymerization conversion rate as described above. For example, in the prepolymerization step, it is preferably 1 to 10 hours, more preferably 1 to 6 hours. In this polymerization step, it is preferably 1 to 16 hours, more preferably 2 to 12 hours.

The polymerization is preferably stopped by adding a polymerization terminator and lowering the polymerization temperature.
Preferred examples of the polymerization terminator include quinone materials such as hydroquinone, dithiocarbamates such as sodium dimethyldithiocarbamate and sodium diethyldithiocarbamate, phenolic materials such as 4-tertiary butylcatechol, and diethylhydroxylamine. It is done. These polymerization terminators may be used alone or in combination of two or more.
Although the addition amount of a polymerization terminator is suitably selected according to the kind, it is about 0.5-3 mol% with respect to a polymerization component, for example. The polymerization termination temperature is preferably 50 ° C. or lower, more preferably 0 to 40 ° C.

After stopping the polymerization as described above, the resulting polymerization solution is filtered, washed with an appropriately selected solvent (for example, methanol, acetone, n-hexane, etc.), and then centrifuged to obtain a polymer. Resin fine particles can be obtained by recovering (fine particles) and drying at a suitably selected temperature and drying period, for example, at 60 to 120 ° C. for 2 to 24 hours.
When the resin fine particles in this embodiment are prepared by emulsion polymerization using an emulsifier or dispersion polymerization using a surfactant, the amount of residual emulsifier and residual surfactant in the resin fine particles is 500 ppm or less by washing with the solvent. It is preferable to make it 2000 ppm or less.

  The average particle diameter of the resin fine particles obtained above is preferably in the range of 50 to 500 nm, and more preferably in the range of 80 to 350 nm. When the average particle diameter of the resin fine particles is 50 nm or more, the progress of the embedding of the resin fine particles into the mother particles is prevented from becoming too fast, and sufficient durability for use as particles having a composite structure can be obtained. On the other hand, when the average particle diameter of the resin fine particles is 500 nm or less, the embedding as the resin fine particles is good, and the particles having a composite structure can be produced favorably.

(Process for reducing the amount of unreacted groups)
When unreacted vinyl groups are present in the resin fine particles, a treatment for reducing the amount of unreacted vinyl groups may be performed. The treatment is not particularly limited as long as the amount can be reduced by oxidizing or addition reaction of unreacted vinyl groups in the resin fine particles. For example, ozone treatment, heat treatment, re-addition reaction treatment, electron Examples thereof include line treatment and hydrogen peroxide treatment.

The ozone treatment is a treatment for oxidizing unreacted vinyl groups by exposing fine particles after polymerization and drying to an ozone atmosphere. As treatment conditions, for example, it is preferable to stand at room temperature for 4 hours or more in an atmosphere having an ozone concentration of 50 ppm or more.
The heat treatment is a treatment in which fine particles after polymerization and drying are heated in air to oxidize unreacted vinyl groups. As treatment conditions, for example, it is preferable to leave the substrate at a heating temperature of 190 ° C. or higher and 250 ° C. or lower for 4 hours or longer.

The re-addition reaction process is a process in which a polymerization initiator or the like is again added to a solution in which resin fine particles are re-dispersed, and an unreacted vinyl group is re-added. As a treatment method, a radical generator such as a polymerization initiator is added to the reaction solution and heated to advance the reaction. In this case, it is preferable to impregnate the radical generator or the like in the fine particles, and from this viewpoint, it is desirable to use an organic solvent together. For example, a solution obtained by dissolving the radical generator or the like in toluene is added to the reaction solution. You may take the method of throwing in. The amount of radical generator and the like to be added is preferably 20% by mass or less based on the resin fine particles.
The hydrogen peroxide treatment may be a treatment in which hydrogen peroxide is introduced into the reaction solution after the completion of polymerization to oxidize unreacted vinyl groups, or the resin fine particles are re-dispersed with a solution containing hydrogen peroxide. You may go. The treatment method is almost the same except that the radical generator or the like in the re-addition reaction treatment is hydrogen peroxide.

The degree of reduction in the amount of vinyl groups by the treatment for reducing the amount of unreacted groups can be determined by analyzing the infrared absorption spectrum of the resin fine particles.
That is, since the absorption of 1630 cm ^-1 in the infrared absorption spectrum of (peak) derived from a vinyl group, an absorption intensity of 1600 cm ^-1 derived from a benzene ring of 100%, the absorption intensity of 1640 cm ^-1 as 0% When normalized, the absorption strength (%) at 1630 cm ⁻¹ is proportional to the amount of residual vinyl groups in the particles.

In the present embodiment, it is preferable to perform heat oxidation treatment until the absorption intensity at 1630 cm ⁻¹ becomes 10% or less. If the absorption intensity is 10% or less, the chargeability of the display particles when display rewriting is repeated in an information display panel using composite display particles using the resin fine particles of the present embodiment. It is possible to stabilize the display particles, thereby improving the durability of the display particles during repeated display rewriting and further improving the display stability of the information display panel.
The absorption intensity at 1630 cm ⁻¹ is preferably 8% or less, and more preferably 5% or less. Ideally, the lower limit is 0%.

  Through the steps described above, the resin fine particles of the present embodiment can be obtained. However, the resin fine particle manufacturing method of the present embodiment only needs to include at least the resin fine particle preparation step, and other steps. May be included. The other steps are not particularly limited.

<Details of display particles>
As described above, the resin fine particles obtained by the manufacturing method according to this embodiment are used as the resin fine particles of display particles in which resin fine particles as shown in FIG. Hereinafter, display particles using the resin fine particles will be described.
In the mother particle 32 in FIG. 1, a charge control agent, a colorant, an inorganic additive, and the like can be included in the resin as the main component as necessary, as in the conventional case. Examples of resins, colorants, and other additives will be given below.

  Examples of the resin include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene Acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluororesin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin, methylpentene resin, cycloolefin resin, etc. It is also possible to mix more than one species. In particular, styrene acrylic resin, acrylic resin, polystyrene resin, polycarbonate resin, methyl pentene resin, and cycloolefin resin are preferable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.
Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.

Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resol red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.
As yellow colorants, yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.

Examples of the orange colorant include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, Indanthrene Brilliant Orange RK, Benzidine Orange G, Indanthren Brilliant Orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.
Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment. Moreover, the said colorant can be mix | blended and the display particle of a desired color can be produced.

In order to obtain the mother particles 33, the resin is first pulverized with a freeze pulverizer, dried and weighed. In parallel with this, a compounding agent (for example, titanium dioxide) to be blended with the resin is prepared and weighed. The weighed base resin and compounding agent are premixed with a Henschel mixer, dried, then kneaded using a twin-screw kneader and extruded, for example, pellets having a diameter of about 2 mm and a length of about 5 mm Manufacturing.
Next, the pellets are further coarsely pulverized with a freeze pulverizer to a particle size of, for example, about 100 to 250 μm to obtain a coarsely pulverized product. After the coarsely pulverized product is dried, it is finely pulverized so as to have a particle diameter of about 8 to 10 μm, and classified to obtain mother particles of a desired size. The steps up to here are the same as those for kneading, pulverizing and classifying the resin raw material by a conventional method to obtain mother particles.

In order to uniformly add the resin fine particles 33 to the surfaces of the mother particles 32 described later, it is effective to spheroidize the mother particles 32 by performing a heat treatment. For this reason, in this embodiment, the mother particles obtained as described above are further processed by a heat treatment apparatus. In this heat treatment apparatus, for example, particles are ejected and dispersed in hot air, the particles are melted by hot air, and spheroidized by surface tension. As the heat treatment apparatus, a melt spheronization apparatus (MR-3, manufactured by Nippon Pneumatic Industry Co., Ltd.) or the like can be used.
The treated mother particles thus subjected to the heat treatment (susfusion treatment) are so-called self-organized arrangement of resin fine particles (Ordered Mixture) when resin fine particles are added to the surface (resin fine particle composite treatment). ) Progresses smoothly, and resin fine particles can be arranged and added uniformly on the surface of the mother particles. Therefore, the composite particle having an ideal shape in which the resin fine particles are uniformly arranged and added to the surface of the spherical mother particle can be produced by the resin fine particle combining treatment.

  The display particles 31 are obtained by embedding (adhering) the resin fine particles 33 according to the present embodiment in the base particles 32 obtained as described above. Embedding can be performed by mixing and stirring the base particles 32 and the resin fine particles 33 using a high-speed stirrer. Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawada Seisakusho Co., Ltd.), Q mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), mechano-fusion system (trade name, Hosokawa Micron Co., Ltd.) Nobil Tamil (trade name, manufactured by Hosokawa Micron Corporation), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), Hybridizer (trade name, manufactured by Nara Machinery Co., Ltd.), and the like.

The composite particles (display particles) obtained by embedding the resin fine particles 33 in the base particles 32 can be subjected to a surface treatment using inorganic fine particles as an external additive.
Examples of the external additive include silica, titanium oxide, aluminum oxide, tin oxide, zirconium oxide, tungsten oxide, yttrium oxide, zinc oxide, calcium oxide, magnesium oxide, barium oxide, calcium carbonate, magnesium carbonate, barium carbonate, Examples thereof include titanium nitride. Of these, silica and titanium oxide are preferred. The average primary particle size of these inorganic fine particles is preferably in the range of 1 to 300 nm, more preferably in the range of 5 to 100 nm. Moreover, you may use what carried out surface treatment to these inorganic fine particles as needed.

  The obtained display particles preferably have an average particle diameter d in the range of 1 to 20 μm and are uniform and uniform. If the average particle diameter d is larger than this range, the display may lack clarity. If the average particle diameter d is smaller than this range, the cohesive force between the particles becomes too large, which hinders movement as display particles. There is a case.

In addition, regarding the particle size distribution of the display particles, the particle size distribution Span represented by the following formula is preferably less than 5, more preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(In the above formula, d (0.5) is a numerical value representing the particle diameter in μm that 50% by volume of the particles are larger than this and 50% by volume is smaller than this, and d (0.1) is a particle smaller than this. (The particle diameter in which the ratio is 10% by volume is expressed in μm, and d (0.9) is the numerical value in which the particle diameter of 90% by volume or less is expressed in μm.)
When the span represented by the above formula is less than 5, the sizes of the display particles are uniform, and movement as uniform display particles becomes possible.

  Furthermore, when an information display panel using two types of display particles having different charging polarities is used, the maximum average particle diameter d (0...) Among the display particles constituting the used information display panel. It is preferable that the ratio of d (0.5) of the display particles showing the minimum average particle diameter d (0.5) to d (0.5) of the display particles showing 5) is 3 or less. That is, even if the particle size distribution Span is reduced as described above, the display particles having different charging characteristics move in opposite directions, so that the display particles can be easily moved to the same size. This is preferred and this is the range.

  The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. That is, when a particle to be measured is irradiated with laser light, a spatial light intensity distribution pattern of diffracted / scattered light is generated, and this light intensity pattern has a corresponding relationship with the particle diameter. It can be measured. Here, the particle size and particle size distribution in the present embodiment are obtained from a volume-based distribution. Specifically, using a Mastersizer 2000 (Malvern Instruments Ltd.) measuring machine, particles were introduced into a nitrogen stream, and the particles were analyzed using the attached analysis software (software based on volume-based distribution using Mie theory). The diameter and particle size distribution can be measured.

<Information display panel>
Next, an example of an information display panel using display particles using the resin fine particles of the above embodiment will be described with reference to FIGS.
In the example shown in FIGS. 2 (a) and 2 (b), at least two or more kinds of display particles that are configured as a particle group having at least optical reflectance and chargeability and have different optical reflectance and charging characteristics are used. (Here, the white display particle group 3W configured to include the white display particles 3Wa and the black display particle group 3B configured to include the black display particles 3Ba are shown.) In the cell, each display particle is changed according to an electric field generated by applying a voltage between an electrode 5 (pixel electrode with TFT) provided on the substrate 1 and an electrode 6 (pixel electrode) provided on the substrate 2. Move perpendicular to the substrates 1 and 2. Then, as shown in FIG. 2A, the white display particle group 3W is visually recognized by the observer to display white dots, or as shown in FIG. 2B, the black display particle group 3B is observed. A black dot display is made to be visually recognized by a person. In addition, in FIG. 2 (a), (b), the partition in front is abbreviate | omitted. The electrodes 5 and 6 may be provided outside the substrates 1 and 2, inside the substrate, or embedded in the substrate.

  Further, in the example shown in FIGS. 3A and 3B, at least two kinds of display particles having different optical reflectance and charging characteristics, which are configured as a particle group having optical reflectance and chargeability, are used. As described above, the white display particle group 3W configured to include the white display particles 3Wa and the black display particle group 3B configured to include the black display particles 3Ba are illustrated in FIG. In each cell, display particles are applied to the substrate 1 in accordance with an electric field generated by applying a voltage between an electrode 5 (line electrode) provided on the substrate 1 and an electrode 6 (line electrode) provided on the substrate 2. 2 and move vertically. Then, as shown in FIG. 3 (a), the white display particle group 3W is visually recognized by the observer and white dot display is performed, or as shown in FIG. 3 (b), the black display particle group 3B is displayed as the observer. The black dots are displayed by visually recognizing. In FIGS. 3A and 3B, the front partition is omitted. The electrodes 5 and 6 may be provided outside the substrates 1 and 2, inside the substrate, or embedded in the substrate.

  In addition, although not shown, one kind of display particles (for example, a white display particle group including white display particles) configured as a particle group having at least an optical reflectance and chargeability is used as one substrate. The display particles are moved in a direction parallel to the substrates 1 and 2 in accordance with an electric field generated by applying a voltage between the electrodes provided on each substrate and encapsulating between the substrates provided with black plates. The white display particle group may be visually recognized by the observer to perform white dot display, or the black plate color may be visually recognized by the observer to perform black dot display.

2 and 3, external electric field forming means is provided outside each of the substrates 1 and 2, and the display particles are placed on the substrate according to the electric field generated by applying a voltage between the external electric field forming means. It is also possible to perform white dot display or black dot display in the same manner by moving vertically to 1 and 2.
Further, a red color filter, a green color filter, and a blue color filter are provided on the observer side of the three cells in FIGS. 2 and 3 in order from the left side of the figure, and the display unit is configured by these three cells. Multi-color display can also be performed by performing white dot display or black dot display and changing the display method in each cell.

Hereinafter, each member which comprises the said information display panel is demonstrated.
As for the substrate, at least one of the substrates is a transparent substrate 2 on which the color of display particles can be confirmed from the outside of the information display panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 1 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and glass and quartz. An inorganic sheet having no flexibility is mentioned. The thickness of the substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm. If the thickness is less than 2 μm, it is difficult to maintain the strength and the uniform spacing between the substrates, and if it is thicker than 5000 μm, it is inconvenient for a thin information display panel.

As an electrode forming material when an electrode is provided on an information display panel as required, metals such as aluminum, silver, nickel, copper, and gold; indium tin oxide (ITO), indium oxide, antimony tin oxide (ATO) ), Conductive metal oxides such as zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), conductive tin oxide, and conductive zinc oxide; and conductive polymers such as polyaniline, polypyrrole, and polythiophene Are appropriately selected and used. As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or a method of laminating a metal foil (for example, rolled copper foil) Alternatively, a method in which the conductive member is mixed with a solvent or a synthetic resin binder and applied. The electrode provided on the display surface side substrate 2 which is on the viewing side and needs to be transparent needs to be transparent, but the electrode provided on the back side substrate 1 does not need to be transparent. In any case, the above-mentioned material that can be patterned and is electrically conductive can be suitably used.
Note that the electrode thickness may be 0.01 to 10 [mu] m, preferably 0.05 to 5 [mu] m, as long as conductivity can be ensured and light transmittance is not hindered. The material and thickness of the electrode provided on the back side substrate 1 are the same as those of the electrode provided on the display surface side substrate described above, but need not be transparent.

The shape of the partition walls 4 provided on the substrate as required is appropriately set according to the type of display particles involved in display, the shape and arrangement of the electrodes to be arranged, and is not limited in general, but the width of the partition walls is 2 The height of the partition wall is adjusted in the range of 10 to 500 μm, preferably in the range of 10 to 200 μm.
In forming the partition wall 4, a both-rib method in which ribs are formed on each of the opposing substrates 1 and 2 and then bonded, and a single-rib method in which ribs are formed only on one substrate are conceivable. In the present embodiment, any method is preferably used.

The cells formed by the ribs 4 made of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction, and the arrangement is exemplified by a lattice shape, a honeycomb shape, or a mesh shape. Is done. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.
Examples of the method for forming the partition walls 4 include a mold transfer method, a screen printing method, a sand blast method, a photolithography method, and an additive method. Any of these methods can be suitably used for the information display panel of the present invention, and among these, a photolithography method using a resist film and a mold transfer method are suitably used.

  Furthermore, when applied to an information display panel of a system in which display particles composed of display particles are driven in a gas space, it is important to manage the gas in the void surrounding the display particles between the substrates, Contributes to improved display stability. Specifically, regarding the humidity of the gas in the void portion, the relative humidity at 25 ° C. is preferably 60% RH or less, and more preferably 50% RH or less. 2 and 3, the gap between the opposing substrate 1 and substrate 2 in FIGS. 2 and 3, electrodes 5 and 6 (when the electrode is provided inside the substrate), the occupied portion of the display particle group 3, A gas portion in contact with a so-called display particle group excluding an occupied portion of the partition wall 4 (when a partition wall is provided) and a panel seal portion for information display is assumed.

  The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be enclosed in an information display panel so that the humidity is maintained. For example, filling of display particles, assembling of the information display panel, etc. are performed in a predetermined humidity environment. It is preferable to apply a sealing material and a sealing method for preventing moisture from entering from the outside.

  The distance between the substrate 1 and the substrate 2 in the information display panel is not limited as long as the display particle group can move and maintain the contrast, but the display particle group including the chargeable display particles is driven in a gas space. When it is made to adjust, it is adjusted to the range of 10-100 micrometers normally, Preferably it is 10-50 micrometers. The volume occupancy of the display particle group in the space in the gas between the opposing substrates is preferably in the range of 5 to 70%, more preferably in the range of 5 to 60%. If it exceeds 70%, the movement of the display particle group may be hindered, and if it is less than 5%, the contrast tends to be unclear.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples. The measurement evaluation method was performed as follows.

(Resin fine particles)
<Compression deformation rate>
The hardness of the resin fine particles was measured as follows using the deformation rate of the resin fine particle aggregate as an index. Specifically, the bottom of the sample filling chamber of a flow tester (CFT-500D: manufactured by Shimadzu Corporation) is sealed, and 1.0 g of child particles are charged, and 300 kg / cm ² (2.94 × 10 ⁷ Pa) is put into the sample. The temperature was raised from 100 ° C. to 175 ° C. while applying a load of. In that case, the height which changed between 125-175 degreeC was read, and the deformation rate was computed by following formula (1).
Deformation rate (%) = [(closest packing height (mm) −height after loading (mm)) / (closest packing height) (mm)] × 100 (1)
The closest packing height is the height when the resin fine particles are charged and the resin fine particles are packed without being deformed and kept in a spherical shape, and is calculated from the following formula (2).
Closest packing height (cm ² ) = weight of resin fine particles introduced (g) / specific gravity of resin fine particles (g / cm ³ ) / cross-sectional area of sample filling chamber (cm ² ) (2)

<Zeta potential>
The zeta potential of the resin fine particles was measured using a zeta sizer nano series manufactured by Simex Co., Ltd. after 10 g of methanol was placed in a sample bottle containing 0.02 g of the sample and dispersed with an ultrasonic cleaner for 10 minutes. .

<Remaining rate of vinyl group>
The vinyl groups remaining in the resin fine particles and the like (vinyl group residual ratio) were measured as follows.
The infrared absorption spectrum of the particles is measured using an infrared spectrometer (manufactured by Digilab, FTS7000). The absorption amount of 1600 cm ^-1 100% normalized absorption of 1640 cm ^-1 as 0%, were obtained vinyl group remaining rate from the absorption amount of 1630 cm ^-1 to it.

(Composite particles)
<Friction charge amount>
The triboelectric charge amount of the composite particles was measured based on the general blow-off method using the following apparatus under the following conditions.
・ Measuring device: Blow-off type charge measuring machine (Kyocera Chemical Co., Ltd., TB-203)
・ Mesh aperture: 32 [μm]
・ Blow pressure / Suction pressure: 4.5 [kPa] /9.5 [kPa]
・ Carrier: F96-80 (Powder Tech)
・ Number of shaking: 1000 times

<Charge retention>
The charge retention characteristics (charge retention) of the composite particles were measured under the following conditions.
(1) Fill a copper cell with a layer having a layer thickness of 300 (μm).
(2) Charge is applied by a scorotron charger (needle applied voltage: ± 10 (kV), grid voltage: ± 1 (kV)) so that the particle surface potential becomes ± 1 (kV).
(3) Connect to ground (GND) and start measurement at room temperature (22 ° C.) and 50 RH%. The charge retention (%) was obtained by dividing the surface potential after 24 hours by the initial surface potential.
Judgment of the charge retention characteristic was judged to be high if the charge retention rate of the composite particles was 90% or more.

<Raw material>
Moreover, in the present Example and the comparative example, the following raw materials were used.
Polymerizable monomer: Styrene (manufactured by Tokyo Chemical Industry Co., Ltd.)
Crosslinkable monomer: divinylbenzene (DVB) “DVB-960” (manufactured by Nippon Steel Chemical Co., Ltd.)
Positively charged monomer: 2-vinylpyridine (manufactured by Tokyo Kasei Reagent)
Emulsifier: Sodium dodecyl sulfate (manufactured by Tokyo Chemical Industry Co., Ltd.)
Polymerization initiator: 2,2′-Azobis [2-methyl-N- (2-hydroxyethyl) propionamide] “VA-086” (manufactured by Wako Pure Chemical Industries, Ltd.)

<Examples and Comparative Examples>
(Preparation of resin fine particles)
Example 1
To the three-necked flask, 1.2 g of the polymerization initiator (VA-086), 0.6 g of the emulsifier (sodium dodecyl sulfate), and 500 g of purified water (manufactured by Ieda Chemical Co., Ltd.) were added in this order to dissolve the polymerization initiator and the emulsifier. I let you. After adding 80 g of the above styrene, a homogenizer was used, and after pre-emulsification at 3000 rpm for 5 minutes at room temperature, bubbling was performed with nitrogen gas at room temperature for 20 minutes. Next, the flask was sealed so that no monomer was leaked from the flask, and then prepolymerization was performed at 90 ° C. 1.5 hours after the start of polymerization, 140 g of purified water was added with an emulsified solution by adding 0.2 g of an emulsifier and 40 g of a mixture of styrene and divinylbenzene at a mass ratio of 1: 1, and the polymerization was continued. went. In addition, 4 hours and 6 hours after the start of prepolymerization, respectively, 140 g of purified water was added with an emulsified solution of 0.2 g of emulsifier and 40 g of divinylbenzene, and the mixture was polymerized for 9 hours from the start of prepolymerization. A dispersed cloudy polymerization dispersion was obtained.
In addition, the polymerization conversion rate (mass%) after preliminary polymerization was calculated | required as follows. The results are shown in Table 1.
(Measurement of polymerization conversion)
After reaching a predetermined time, about 5 g of the reaction solution was extracted from the three-necked flask and transferred to a vial and rapidly cooled to room temperature. Thereafter, about 3 g of the reaction solution was weighed in an aluminum cup, dried at 120 ° C. for 1 hour using a hot air oven (Advantech, DRA430DA), and the weight of the remaining polymer was measured. The polymer solid content in the reaction solution was calculated from the following formula (a), and the polymerization conversion rate was calculated from the following formula (b).

  After adding 800 g of methanol to 1000 g of this dispersion and stirring for 5 minutes, the mixture was centrifuged at 6900 rpm for 1 hour using a centrifuge (manufactured by Kokusan Co., Ltd., HL-7). After 1 hour, the solid content (resin fine particles) and the solution were separated into solid and liquid, and the solution was transparent. After removing the solution, 400 g of methanol was added and stirred for 2 hours, and then centrifuged at 6900 rpm for 15 minutes using a centrifuge to remove the supernatant. This operation was repeated four more times, followed by vacuum drying at 80 ° C. for 1 day. 30 g of the produced resin fine particles were placed in a glass petri dish (diameter 20 cm) and heated at 200 ° C. using a hot air oven (Advantech, DRA430DA). Heat treatment was performed for a time to obtain resin fine particles. The properties of the obtained resin fine particles were evaluated by the measurement evaluation method described above. The results are shown in Table 1.

(Preparation of white mother particles)
100 parts by mass of ethylene-cycloolefin copolymer (manufactured by Polyplastics Co., Ltd., TOPAS 6013) and 100 parts by mass of titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd., Tycop CR-50) are mixed and kneaded with a biaxial kneader. A kneaded product was obtained. This was pulverized and classified with a jet mill (manufactured by Nippon Pneumatic Co., Ltd., Lab Jet Mill IDS-LJ type) to obtain white mother particles having an average particle diameter of 10 μm.

(Production of composite particles)
The resin fine particles obtained above were used as child particles, and composite particles composed of this and mother particles were produced.
The composite particles use the above-mentioned ethylene-cycloolefin copolymer spherical particles having an average particle diameter of 10 μm as mother particles and the resin fine particles obtained above as child particles, and a composite device (manufactured by Hosokawa Micron Corporation, Novir Tamil (NOB-130)). ) Was used to embed the child particles in the mother particles so that the input energy was 2400 kJ.
The properties of the obtained composite particles were evaluated by the measurement evaluation method described above. The results are shown in Table 1.

Example 2
(Preparation of resin fine particles)
A polymerization initiator and an emulsifier were dissolved in a three-necked flask in the order of VA-0861.2 g, sodium dodecyl sulfate 0.6 g, and purified water 500 g. After adding 68 g of styrene, a homogenizer was used, and after pre-emulsification at 3000 rpm for 5 minutes at room temperature, bubbling was performed with nitrogen gas at room temperature for 20 minutes. Next, the flask was sealed so that no monomer was leaked from the flask, and then prepolymerization was performed at 90 ° C. 1.5 hours after the start of polymerization, 140 g of purified water was added with an emulsified solution by adding 0.2 g of an emulsifier and 88 g of a mixture of styrene and divinylbenzene at a mass ratio of 3: 1, and the polymerization was continued. went. In addition, after 4 hours and 6 hours from the start of prepolymerization, a solution obtained by emulsifying 0.2 g of emulsifier and 22 g of divinylbenzene was added to 140 g of purified water, respectively. A dispersed cloudy polymerization dispersion was obtained. Thereafter, washing, drying, and heat oxidation treatment operations were performed in the same manner as in Example 1 to obtain resin fine particles. The properties of the obtained resin fine particles were evaluated by the measurement evaluation method described above. The results are shown in Table 1.
(Production of composite particles)
Composite particles were produced in the same manner as in Example 1, and their properties were evaluated. The results are shown in Table 1.

Comparative Example 1
Polymer fine particles and composite particles were produced in the same manner as in Example 1 except that the polymerization initiator, emulsifier, purified water, styrene and divinylbenzene mixed solution were all added to a three-necked flask and polymerization was started. The properties of the obtained resin fine particles and composite particles were evaluated. The results are shown in Table 1.

Comparative Example 2
Polymer fine particles and composite particles were produced and obtained in the same manner as in Example 2 except that the polymerization initiator, emulsifier, purified water, styrene and divinylbenzene were all charged into a three-necked flask and polymerization was started. Properties of resin fine particles and composite particles were evaluated. The results are shown in Table 1.

Comparative Example 3
A polymerization initiator and an emulsifier were dissolved in a three-necked flask in the order of VA-0861.2 g, sodium dodecyl sulfate 0.8 g, and purified water 500 g. After adding 90 g of the above styrene, a homogenizer was used, and after pre-emulsification at 3000 rpm for 5 minutes at room temperature, bubbling was performed with nitrogen gas at room temperature for 20 minutes. Next, after sealing the flask so that the monomer would not leak from the flask, prepolymerization was performed at 90 ° C. 1.5 hours after the start of polymerization, 0.2 g of an emulsifier and 100 g of a mixed solution of styrene and divinylbenzene in a mass ratio of 9: 1 were added to 140 g of purified water, and an emulsified solution was added. went. Further, after 4 hours and 6 hours from the start of prepolymerization, an emulsified solution of 0.2 g of emulsifier and 22 g of divinylbenzene was added to 140 g of purified water, respectively. A dispersed cloudy polymerization dispersion was obtained. Thereafter, washing, drying, and heat oxidation treatment operations were performed in the same manner as in Example 1 to obtain resin fine particles. The properties of the obtained resin fine particles were evaluated by the measurement evaluation method described above. The results are shown in Table 1.
(Production of composite particles)
Composite particles were produced in the same manner as in Example 1, and their properties were evaluated. The results are shown in Table 1.

  From the results of Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, by using a method comprising a prepolymerization step and a main polymerization step, the charge amount is high with a higher yield than the batch preparation even with the same composition. It can be seen that particles can be produced. This is considered to be due to the following. As the amount of the crosslinking agent increases, the negative chargeability of the zeta potential tends to increase. The polymerization rate of divinylbenzene is faster than that of styrene, and in the batch charge, almost no divinylbenzene remains in the reaction liquid in the late stage of polymerization, and the composition of the particle surface is considered to form a structure rich in styrene. On the other hand, by adding divinylbenzene during the polymerization (using this method), it is possible that divinylbenzene is present in the reaction solution even in the late stage of polymerization, and the composition of divinylbenzene on the particle surface can be increased. Conceivable. Further, as in Comparative Example 3, when divinylbenzene was less than 25% by mass, the compression deformation rate was high and the hardness was insufficient, so that it could not be combined.

Example 3
(Preparation of black mother particles)
100 parts by mass of ethylene-cycloolefin copolymer (manufactured by Polyplastics Co., Ltd., TOPAS6013) and 5 parts by mass of carbon black (Evonik-Degussa Co., Ltd., SPECIAL BLACK4) were mixed and kneaded by a twin-screw kneader. To obtain a kneaded product. This was pulverized and classified with a jet mill (manufactured by Nippon Pneumatic Co., Ltd., Lab Jet Mill IDS-LJ type), and then melt spheroidizing apparatus (METOLEINBO MR-3: manufactured by Nippon Pneumatic Industry Co., Ltd.). Melt spheroidization gave black mother particles having an average particle size of 10 μm.

(Preparation of positively charged particles)
In a three-necked flask, 1.2 g of the polymerization initiator (VA-086), 0.7 g of the emulsifier (sodium dodecyl sulfate), and 500 g of purified water (manufactured by Ieda Chemical Co., Ltd.) are added in this order, and the polymerization initiator and the emulsifier are dissolved. I let you. After adding 114 g of styrene, 66 g of divinylbenzene and 20 g of 2-vinylpyridine, a pre-emulsification was performed at 3000 rpm for 5 minutes at room temperature using a homogenizer, and then bubbling was performed with nitrogen gas at room temperature for 20 minutes. The flask was sealed so that no monomer would escape from the flask, and then polymerized at 90 ° C. for 8 hours to obtain a cloudy polymerization dispersion in which resin fine particles were dispersed.

  After adding 800 g of methanol to 1000 g of this dispersion and stirring for 5 minutes, the mixture was centrifuged at 6900 rpm for 1 hour using a centrifuge (manufactured by Kokusan Co., Ltd., HL-7). After 1 hour, the solid content (resin fine particles) and the solution were separated into solid and liquid, and the solution was transparent. After removing the solution, 400 g of methanol was added and stirred for 2 hours, and then centrifuged at 6900 rpm for 15 minutes using a centrifuge to remove the supernatant. This operation was further repeated four times, followed by vacuum drying at 80 ° C. for 1 day to obtain positively charged particles.

(Preparation of black display particles)
Display particles, which are composite particles composed of mother particles and child particles, were produced. As the mother particles, the aforementioned black mother particles having an average particle diameter of 10 μm were used, and as the child particles, the aforementioned positively charged child particles were used. Using a compounding device (Hosokawa Micron Co., Ltd., Nobil Tamil (NOB-130)), 100 parts by weight of black mother particles and 10 parts by weight of positively charged child particles are mixed so that the input energy is 2400 kJ. The child particles were embedded and combined to produce black composite particles.

  Further, 100 g of the composite particles (1) and 4.9 g of positively charged silica (manufactured by WACKER, HDK H3050VP) as an external additive (coverage: 1000%) were mixed in advance, and then a carbon mixer processor (SMT Co., Ltd.). ), HFM-001C), and stirred at 4000 rpm so that the external additive is uniformly applied to the surface of the composite particles to produce black display particles.

(Preparation of white display particles)
Further, 100 g of the composite particles prepared in Example 1 and 1.7 g of negatively chargeable silica (HDK H3004: manufactured by WACKER) as an external additive (coverage: 350%) were mixed in advance, and then a carbon mixer processor ( SMT Co., Ltd. product: HFM-001C) was stirred at 4000 rpm, and processing was performed so that the external additive was uniformly applied to the surface of the composite particles to produce white display particles.

(Production of display panel)
The display panel is manufactured by combining the black display particles and the white display particles prepared as described above at a mass ratio of 6: 8, and between the panels on which the transparent electrode (ITO) is formed, The filling was performed so that the particle filling amount was 5 g / m ² . The panel used has an electrode distance of 40 μm, and an electric field of 2 × 10 ⁶ (V / m) is applied to the display particles when a voltage of 80 V is applied.
The obtained display panel was subjected to the following durability test, light durability test and display holding performance evaluation test. The results are shown in Table 2.

[An endurance test]
A white display and a black display were performed on the evaluation panel by applying a voltage of 80 V between the electrodes of the panel manufactured as described above in opposite directions. And in each of white display and black display, the OD value (optical density) was measured using an optical densitometer (manufactured by Sakata Inx Engineering Co., Ltd., RD19I). The contrast ratio (CR = 10 ^(BOD-WOD) ) was calculated based on the OD value (WOD) for white display and the OD value (BOD) for black display, and this was used as an index of panel performance. The CR after 1000 black-and-white reversal display driving with 80 V applied was evaluated as the initial CR, and the durability test was performed using a fluorescent lamp (Toshiba, Paralite Flat D65FL20) so that the illuminance was 600 lx. In this state, the CR was measured after the black-and-white inversion display drive with 80 V applied was performed 800,000 times.
[Light durability test]
The measurement was performed in the same manner as in the durability test except that the illuminance of the fluorescent lamp was set to 4000 lx.
[Display retention performance evaluation test]
The CR after the black and white inversion display drive with 100 V applied between the electrodes of the panel produced as described above was performed 1000 times was evaluated as the initial CR. The evaluation after endurance was performed by performing black and white inversion display driving with 100 V applied to the panel after the initial CR evaluation 600,000 times and then leaving it in an environment maintained at 77 ° C. for 2 weeks in order to promote charge decay. The CR after applying a vibration of 5 kHz was evaluated as a post-endurance CR under conditions of 77 ° C. and 25% RH using a vibration tester (Emic Co., Ltd.). The case where the initial value and the CR after the durability test were CR> 5.0 was determined to be acceptable (◯), and the case where CR ≦ 5.0 was determined to be unacceptable (x).

Example 4
A display panel is produced in the same manner as in Example 3 except that the composite particles produced in Example 2 are used instead of the composite particles produced in Example 1, and the performance is evaluated. did. The evaluation results are shown in Table 2.

Comparative Example 4
A display panel was produced in the same manner as in Example 3 except that the composite particles produced in Comparative Example 1 were used instead of the composite particles produced in Example 1, and the performance was evaluated. did. The evaluation results are shown in Table 2.

Comparative Example 5
A display panel was produced in the same manner as in Example 3 except that the composite particles produced in Comparative Example 2 were used instead of the composite particles produced in Example 1, and the performance was evaluated. did. The evaluation results are shown in Table 2.

  As shown in Table 2, when the charge amount of the white display particles is large, good CR is maintained for a long time, whereas when the charge amount is small as in Comparative Examples 1 and 2, it is left for a long time. It turns out that CR falls by doing. This is because, when the charge amount of the display particles is small, the adhesion force (charge mirror image force) to the substrate is originally low, and the charge mirror image force due to the charge decay of the particles can be left for a long time without rewriting. This is considered to be due to a decrease and desorption from the substrate.

  An information display panel that employs display particles combined with resin fine particles obtained by the production method of the present invention includes a notebook personal computer, an electronic notebook, a PDA (Personal Digital Assistants), a portable information device, and a mobile phone. , Display units for mobile devices such as handy terminals, electronic paper such as electronic books, electronic newspapers, electronic manuals (electronic instruction manuals), signboards, posters, bulletin boards such as blackboards and whiteboards, electronic desk calculators, home appliances, automobiles Display section of goods, card display section such as point card, IC card, electronic advertisement, information board, electronic POP (Point Of Purchase, Point Of Purchase advertising), electronic price tag, electronic shelf label, electronic score, RF-ID device In addition to the display part POS terminals, car navigation system, in addition to a display portion of various electronic devices such as watches, also suitably used as a so-called rewritable paper which rewrites the display by using an external electric field forming means or an external rewrite means only when the display rewriting.

1, 2 Substrate 3W White display particle group 3Wa White display particle 3B Black display particle group 3Ba Black display particle 4 Partition wall 5, 6 Electrode 31 Display particle 32 Base particle 33 Charged resin fine particle

Claims (8)

Display particles formed by fixing resin fine particles on the surface of the mother particles are sealed between two opposing substrates, at least one of which is transparent, and the display particles are moved by applying an electric field between the substrates. A method for producing resin fine particles constituting the display particles used in an information display panel for displaying image information,
Polymerization is performed by adding a prepolymerization step in which a polymerizable monomer having one polymerizable functional group in a molecule is polymerized to form particle nuclei and a polymerization component containing a crosslinkable monomer having two or more vinyl groups in the molecule. The main polymerization step is performed in this order,
A method for producing resin fine particles, wherein the ratio of the crosslinkable monomer to the total of the polymerizable monomer and the crosslinkable monomer in the preliminary polymerization step and the main polymerization step is 25% by mass or more.   The method for producing resin fine particles according to claim 1, wherein the polymerization component in the main polymerization step further includes a polymerizable monomer having one polymerizable functional group in the molecule.   The method for producing resin fine particles according to claim 2, wherein a ratio of the crosslinkable monomer to the total of the polymerizable monomer and the crosslinkable monomer in the main polymerization step is 25 to 90% by mass.   The method for producing resin fine particles according to any one of claims 1 to 3, wherein the polymerization component is added a plurality of times in the main polymerization step.   The resin fine particle according to any one of claims 1 to 4, wherein the crosslinkable monomer having two or more vinyl groups in the molecule is at least one selected from divinylbenzene, divinylnaphthalene, divinylbiphenyl and ethylene glycol dimethacrylate. Manufacturing method.   The method for producing resin fine particles according to claim 1, wherein the polymerizable monomer having one polymerizable functional group in the molecule is a monomer having one vinyl group.   The method for producing resin fine particles according to any one of claims 1 to 6, wherein the preliminary polymerization step and the main polymerization step are performed by an emulsion polymerization method. Display particles formed by fixing resin fine particles on the surface of the mother particles are sealed between two opposing substrates, at least one of which is transparent, and the display particles are moved by applying an electric field between the substrates. Resin fine particles constituting the display particles used in an information display panel for displaying image information,
Resin fine particles produced using the method for producing resin fine particles according to claim 1.

Images