JPH04182667A - Toner and production of toner - Google Patents

Abstract

PURPOSE:To easily produce toner having desired dielectric constant at low cost by forming a resin coating layer on the outer surface of the inner core with using resin fine particles and inorg. fine particles. CONSTITUTION:The toner inner core consists of at least a binder component and colorant, and is produced by kneading the source material and pulverizing. To this toner core, resin particles and inorg. fine particles are added externally depositing on the core surface to produce the toner covered with resin particles and inorg. fine particles. Then this toner is treated with a solvent for coating, and thus, the toner for electrophotography is obtd. The inorg. fine particles are SiO2, TiO2 (rutile, anatase), etc. As for the solvent used to dissolve the resin fine particles after the mixture powder is deposited on the core surface, the solvent is decided according to the physical properties of the inner core and fine particles. For example, dichloromethane, chloroform, etc., is used. Thereby, by forming a resin coating layer containing inrog. fine particles, the obtd. toner has excellent storage property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a toner for forming images using electrophotographic technology for use in printers, copiers, facsimile machines, and the like. More specifically, the present invention relates to a toner having a multilayer structure.

[Prior Art] In the developing device of an image forming apparatus using conventional electrophotographic toner, magnetic powder such as iron powder is used as a carrier.
A method using a two-component developer (for example, C, H) in which the toner is attached to the surface of the carrier by electrostatic force, and the movement of the carrier by the magnetic force is used to transport the toner and develop the electrostatic image carrier.

Young H,G, Greig:R,C
,A.

15 (4), 471 1950) has been adopted.

In the two-component development method, the carrier acts as an electrode near the electrostatic image carrier, and the shape of the electric lines of force generated on the outer surface of the electrostatic image carrier can be modified to emphasize the so-called developing electric field, so that the entire image area can be Uniform and high temperature development was possible.

However, this method has major disadvantages in that the life of the developing device is short due to deterioration of the carrier, and that the structure of the developing device and the control of the toner within the developing device are complicated in order to always maintain a constant mixing ratio of carrier and toner. For this reason, the two-component development method was only used in relatively advanced high-speed image forming apparatuses.

In order to solve these problems, a two-component development method (for example, U, S, P, 4121
A small, low-speed image forming apparatus using the image forming apparatus (No. 931) has been put into practical use. Toner may be conductive or insulating, but insulating toner is widely used from the viewpoint of transfer efficiency of toner onto recording paper. The specific resistance of the toner in the aggregated state of the powder was approximately 1013 to 1015 Ω0, and the specific galvanic rate was approximately 3, which was a typical value.

Generally, the insulating toner used in these development methods is made by dispersing colorants such as dyes and pigments, charge control agents, etc. in resin, and having various substances attached to the surface of fine particles of about 10 μm. has been done. However, in order to use these fine powders in the above development method, various chemical and physical properties are required. Among these, many proposals have been made to date regarding cohesiveness and fluidity, which affect toner transport. For example, it is generally known that fluidity can be improved by attaching silica powder to the surface of toner. . Recently, Japanese Patent Publication No. 62-494 discloses coating the surface of a toner with a combination of silica dispersed in polyvinyl alcohol. In addition, special public service 61-551
No. 08 discloses that fine inorganic powder is attached to the surface of a toner via an adhesive layer made of silicone resin.

Furthermore, Japanese Patent Publication No. 60-34104 discloses a developer in which rM powder silica is further mixed with toner particles containing fine powder silica.

Generally known methods for producing toner include a kneading and pulverizing method, a spray drying method, and a polymerization method.

Among these, the kneading and pulverizing method is the most commonly used. As a method for attaching various substances to the toner surface, there are known methods such as a method of attaching by heat using a fluidized drying oven or the like, and a method of attaching by mechanical force using a mixer such as a ball mill. Further, there are a spray drying method, a spray granulation method, and the like. Furthermore, in recent years, toners having various structures and manufacturing methods have been proposed due to demands for higher functionality of toners and advances in manufacturing technology. A structure having a conductive layer and an insulating layer on the surface of the toner particles, in which conductive particles are immobilized on the surface of the toner particles in a hot air flow, and insulating particles are further immobilized around the conductive particles in a hot air flow. 1986
-257763), and microcapsule toners (U.S. Pat.
No. 080250, Special Publication No. 59-31066, Special Publication No. 1-
36934, etc.), and a toner that has a charge control resin film layer on the outer periphery of the toner for the purpose of charge control using a dry high-speed impact method (JP-A-63
-62666), toner whose surface is treated with resin fine powder for blocking resistance (JP-A-1-105
261) etc.

[Problems and Objectives to be Solved by the Invention] However, in the methods proposed in Japanese Patent Publication No. 62-494 and Japanese Patent Publication No. 60-34104, the adhesion force of fine particles attached to the surface is weak, and the toner is It peels off from the surface and easily aggregates depending on the operating atmosphere temperature.
It has the disadvantage that the developing characteristics of the toner deteriorate due to blocking and caking. Furthermore, the peeled off particles contaminate the inside of the apparatus, resulting in negative effects such as image deterioration and mechanical failure.

Furthermore, when 5i02 particles are immobilized by a polymerization method, there is a drawback that material selectivity becomes extremely narrow. Furthermore, each toner has a different amount of charge depending on the amount of fine particles attached to its surface, which has a disadvantage in that it adversely affects image quality.

Furthermore, in the manufacturing method proposed in JP-A No. 63-257763, heat treatment is performed, which causes material deterioration. Since the treatment is performed twice using inorganic fine particles of carbon black and silica, there are problems such as the inability to obtain the desired resistance by mixing the two types. Furthermore, in the conventional polymerization method, spray drying method, and spray granulation method, the conditions for forming the coating layer are strictly controlled, and the materials are limited. Furthermore, there are other problems such as the inability to freely control the thickness of the coating layer and the complicated manufacturing method. Furthermore, the dry high-speed impact method has the problem that if the viscosity of the core particles is lower than the viscosity of the fine particles, it is difficult to release the fine particles and form a uniform film.

Therefore, an object of the present invention is to solve the above-mentioned problems. 1) Prevention of agglomeration (storability) 2) High fluidity 3) Prevention of fine particle scattering 4) Stable charging property Having a desired dielectric constant that satisfies the above characteristics. The present invention provides a toner and a method for manufacturing the toner simply and at low cost.

[Means for Solving the Problems] The toner of the present invention is composed of at least a binder resin and a colorant, has at least a two-layer structure, the outermost shell layer exhibits electrical insulation, and the inner core The toner has an effective dielectric constant higher than that of the outermost shell layer, and is characterized in that a resin coating layer is formed on the outer surface of the inner core particles using inorganic fine particles and resin fine particles. Further, in the resin coating layer containing inorganic fine particles, the inorganic fine particles are exposed inside and on the outer surface of the coating layer.

Further, in the toner manufacturing method of the present invention, mixed particles of inorganic fine particles having a particle size of 0.1 μm or less and resin fine particles having a particle size of 1 μm or less are attached to the outer surface of the inner core particles, and then the resin fine particles are dissolved. It is characterized by forming a resin coating layer containing inorganic fine particles by treating with a solvent.

In addition, the content of inorganic fine particles contained in the coating layer is 100 to
It is characterized by being in the range of 200%. Another feature is that the mixed particles of inorganic particles and resin particles are attached to the surface of the inner core particles in a dry manner.

[Function] When the inner core particles contain a highly dielectric material, the relative permittivity of the entire toner increases, and the relative permittivity of the gap within the development gap increases. As a result, the toner near the toner being developed acts as an electrode near the electrostatic image carrier, like a carrier in a two-component development system, and modifies the shape of the electric force lines generated on the outer surface of the electrostatic image carrier. It is believed that it plays the role of emphasizing the developing electric field, thereby making it possible to further stabilize the developing electric field and reduce edge effects. In addition, by maintaining the electrical insulation between the toner particles, the toner can be stably charged, and when the toner, which has been developed on the latent image carrier and has become a visible latent image, is electrostatically transferred onto the recording paper, the toner It is believed that an image of excellent quality is formed because a charge having a polarity opposite to that of the toner is injected into the toner, thereby preventing transfer defects from occurring.

On the other hand, it is generally known that the fluidity of toner is improved by attaching silica or the like to the toner surface, but the detailed causes of this are still unclear. After conducting intensive research on this point, it became clear that when a mixture of an inorganic substance and a resin is attached to the toner surface using a dry process and a solvent that dissolves the resin is brought into contact with the toner, the resin dissolves and the inorganic substance is dispersed within it. Ta. As a result, the inorganic fine particles are exposed not only inside but also on the surface, and it is thought that they form a strong bond with the resin. For this reason, it has become clear that fluidity and storage stability are improved compared to conventional attachment methods. However, at this time, when the particle size of the resin fine particles was increased to 1 μm or more, the thickness of the coating layer became large, the dispersion of the inorganic fine particles became uneven, and the fluidity deteriorated.

Furthermore, similar results were obtained when the particle size of the inorganic fine particles was larger than 0.1 μm. Furthermore, when the coverage of 1 of the inorganic fine particles on the surface of the resin fine particles was reduced to 100% or less, the number of inorganic fine particles exposed on the surface decreased, and the fluidity deteriorated. Moreover, when it exceeds 200%, inorganic fine particles begin to peel off.

Furthermore, according to the toner manufacturing method of the present invention, a resin coating layer can be formed even when the inner core particles have a lower softening point and are softer than the resin fine particles. It is thought that the adhesion of the fine particles is due to electrostatic force, adhesive force, intermolecular force, etc., and therefore they adhere quite firmly. For this reason, it is thought that even if the solvent treatment is performed, the fine particles will not be peeled off from the surface of the inner core particles and will be formed into a film. Forming a film with a solvent is performed by bringing the solvent into contact with the surface of the inner core particles to which the fine particles are attached. It is also believed that since the solvent is quickly evaporated and removed from the particles by heat, it is possible to prevent the particles from coagulating with each other. Furthermore, by controlling the contact time of the solvent, it is possible to form a film without affecting the inner core particles.

Hereinafter, the details of the present invention will be shown by examples.

[Example] A flowchart of the method for producing toner of the present invention is shown in FIG. FIG. 1 shows the most general method for manufacturing the toner of the present invention. 6. The toner inner core has at least 1. Consisting of a binding component and a coloring agent, these raw materials are 9. kneading,
10. Create by crushing. 6. Toner inner core prepared in this way, 3. Resin particles and 4. 11. Inorganic fine particles. External addition treatment and attachment; 7. A toner with external additives of resin particles and inorganic particles is prepared. And 5. 12. Coating treatment using a solvent; 8. Produce toner for electrophotography.

The method for producing the toner will be described in more detail. The core particles used in the present invention are particles containing a binder resin and at least one type of toner component. As toner components, a colorant, a charge control agent, a magnetic powder, a conductive agent, a mold release agent, a dispersant, etc. are selected as necessary. These inner core particles are produced using the general cross-wire crushing method, spray drying method,
Particles produced by a polymerization method and having a particle size of 1 to 40 μm are used. The shape may be spherical or irregular.

As the coating fine particles, a mixed system containing resin fine particles and at least one kind of inorganic fine particles can be used. As a dry method for adhering the mixed powder of inorganic fine particles and resin particles to the surface of the inner core particles, ordinary mixers such as ball mills and V-type mixers can be used, but it is preferable to use a so-called high-speed fluidized stirrer. preferable. As the high-speed fluidized stirrer, a so-called Henschel mixer (Mitsui Miike Kakoki), Mechano Fusion System (Hosokawa Micron), Nara Hybridization System (Nara Kikai Seisakusho), Mechano Mill (Okada Seiko), etc. are used.

However, the devices for fixing inorganic particles and resin particles to the surface of the inner core particles are by no means limited to these.Next, methods for treating the solvent include spray drying, immersion, etc. Any device that can save time may be used, preferably a powder coating device such as Disper Coat (Nissin Seifun), Coat Mizer (
Freund Industries) etc.

The composition of the inner core particle is not particularly limited,
- You can use fishing equipment.

For example, binder resins include polystyrene and copolymers,
For example, hydrogenated styrene resin, styrene-isobutylene copolymer, ABS resin, ASA resin, As resin, AA
SAs resin C3 resin, ABS resin, styrene/P-chlorostyrene copolymer, styrene/propylene copolymer, styrene/butadiene crosslinked polymer, styrene/butadiene/chlorinated paraffin copolymer, styrene/allyl/alcohol copolymer, Styrene/butadiene rubber emulsion, styrene/maleic acid ester copolymer, styrene/isobutylene copolymer, styrene/maleic anhydride copolymer, acrylate resin or methacrylate resin and its copolymer, styrene/acrylic resin Resins and copolymers thereof, such as styrene/acrylic copolymer, styrene/diethylamino/ethyl methacrylate copolymer, styrene/butadiene/acrylate ester copolymer, styrene/methyl methacrylate copolymer, styrene/n -butyl methacrylate copolymer,
Styrene/diethylamino/ethyl methacrylate copolymer, styrene/methyl methacrylate/n-butyl acrylate copolymer, styrene/methyl methacrylate/butyl arylate/N-(ethoxymethyl)acrylamide copolymer, styrene/glycidyl methacrylate Copolymer, styrene, butadiene, dimethyl,
Aminoethyl methacrylate copolymer, styrene/acrylic acid ester/maleic ester copolymer, styrene/methyl methacrylate/2-ethylhexyl acrylate copolymer, styrene/n-butyl arylate/ethyl glycol methacrylate copolymer Combined, styrene
n-butyl methacrylate/acrylic acid copolymer, styrene/n-butyl methacrylate/maleic anhydride copolymer, styrene/butyl acrylate/inbutylmaleic acid half ester/divinylbenzene copolymer, polyester and its copolymer One or more blends of polyethylene and its copolymers, epoxy resins, silicone resins, polypropylene and its copolymers, fluorocarbon resins, polyamide resins, polyvinyl alcohol resins, polyurethane resins, polyvinyl butyral resins, etc. You can use things. Moreover, wax etc. can also be used as a substance other than resin. For example, candelilla wax, carnauba wax,
Plant-based natural waxes such as rice wax, animal-based natural waxes such as beeswax and lanolin, mineral-based natural waxes such as montan wax and osikelite, paraffin wax, microcrystalline wax, natural petroleum waxes such as petrolatum, polyethylene wax, and Fischer wax. Synthetic hydrocarbon waxes such as Tropsch wax,
Modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, waxes such as synthetic waxes, higher fatty acids such as stearic acid and balmitic acid, low molecular weight polyethylene, oxidized polyethylene, polypropylene One or more olefin copolymers such as ethylene/acrylic acid copolymer, ethylene/acrylic acid ester copolymer, ethylene/vinyl acetate copolymer, etc. are used.

As the coloring agent, black dyes and pigments such as carbon black, spirit black, and nigrosine are used. For colors, dyes or pigments such as phthalocyanine, rhodamine B lake, Solar Pure Yellow 8G, quinacridone, polytungstophosphoric acid, industhrene blue, and sulfonamide derivatives can be used. Furthermore,
Dispersants include metal soaps and polyethylene glycol; charge control agents include electron-accepting organic complexes, chlorinated polyesters, nitrofumic acids, quaternary ammonium salts,
Pyridinyl salts and the like can be added. In addition, magnetic powders such as Fe3O4 and Fe are used as magnetic toners.
2O3, Fe, Cr, Ni, etc. are used.

Next, as the inorganic fine particles used in the present invention, 5i02,
TiO2, (rutile, anatase), Zn0, A120
3 (α type, β type), TiON, TiBaO3, MgO,
ZrO2, Ca CO3, NiO, SnO, clay, talc, silica sand, mica, SiN, S i C, B a2s
04, fine particles such as carbon black can be used. In addition, resin particles include polymethyl methacrylate, polyethyl methacrylate, poly n-butyl methacrylate, polyester, (styrene-butadiene) copolymer, (PVC, PVA, PVAc).
cobo')mer, polyγ-methyl-glutamate, fluororesin, vinylidene fluoride resin, penzoquanamine resin, silicone resin, epoxy resin, nylon 66/6,
Nylon 11, nylon 12, polystyrene resin, crosslinked polystyrene resin, phenol resin, melamine resin, polyolefin resin, polyethylene resin, cellulose, etc. are used.

After adhering the mixed powder to the surface of the inner core particles, the solvent for dissolving the resin fine particles may be determined depending on the materials of the inner core particles and the fine particles. For example, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, chlorobenzene, etc. halogenated carbons, methanol, methyl cellosolve, alcohols such as benzyl alcohol, dioxane,
Ethers such as tetrahydrofuran and pencil ether, esters such as ethyl acetate and butyl acetate, ketones such as furfural, acetone, methyl ethyl ketone and cyclohexanone, aromatics such as benzene, toluene and xylene, nitrobenzene, acetonitrile, diethylamine, aniline, Nitrogen compounds such as dimethylformamide and pyrrolidone can be used.

By forming a resin coating layer containing inorganic fine particles by the method described above, a toner with excellent fluidity and storage stability can be easily produced without the need for operations such as classification after treatment.

This example will be explained in more detail below.

[Example 1] (Preparation of inner core particles) Styrene-acrylic copolymer 44wt%Fe3O
446 wt% carbon black 10 wt% The raw materials having the above composition are kneaded with a twin-screw extruder, cooled and coarsely pulverized. Next, the mixture was finely pulverized using a jet pulverizer, and then classified to produce inner core particles with an average particle diameter of 10 μm and a distribution of 5 to 25 μm.

The specific resistance and dielectric constant of the inner core particles were measured.

The measurement method is to fill particles between parallel plate electrodes,
Apply a pressure of g/cm 2 and additionally an electric field of 2k
v/cm was applied to determine the specific resistance. To measure the relative dielectric constant, particles were packed between the electrodes in the same way as in the specific resistance measurement, and the frequency was 1kHz.
It was measured by multiplying by z. As a result, the specific resistance is 5X103Ω
cm, and the relative dielectric constant was 400.

(Adherence of Inorganic Fine Particles and Resin Particles) For the inner core particles, 5i02 with a particle size of 0.02 μm was used as the inorganic fine particles, and polybutyl methacrylate (PBMA) was used as the resin fine particles. The particle size of PBMA is 0.4μm
, with a glass transition point of 83°C. The inorganic fine particles, the resin fine particles, and the above-mentioned inner core particles were mixed in the composition shown below, and the mixture was attached to the surface of the inner core particles using a mechanofusion system (manufactured by Hosokawa Micron). The composition and conditions are shown below.

Sio2 10wt% PBMA fine particles 15wt% inner core particles
75wt% At this time, 5io2Jl is PBMA
The surface coverage was approximately 150%. The mechano conditions were a rotation speed of 1500 rpm and a processing time of 30 minutes. Excess PBMA particles that did not contribute to adhesion of the obtained powder particles were removed using a classifier. When the particles after classification were observed using an electron microscope, it was found that PBMA particles and 5iO21
It became clear that the d particles were not peeled off but adhered to the surface of the inner core particles. In addition, cross-sectional observation using an electron microscope revealed that the PBMA particles remained spherical on the surface of the inner core particles.
It was observed that it was in an embedded state.

(Solvent Treatment) The inner core particles to which the fine particles produced by the above method were attached were subjected to a solvent treatment. Acetone was used as the solvent. The powder was brought into contact with this solvent for 1.0 seconds, and then the drying temperature was 60°C.
The acetone was evaporated by spray drying at °C. The particles obtained by this solvent treatment had no binding between particles, and each particle was an aggregate in an independent state. Furthermore, when the cross section of the particles produced in this example was observed using an electron microscope, it was found that a resin coating layer of 0.5 to 1.0 μm was formed on the surface of the inner core particle. Furthermore, it was confirmed that 5i02 was uniformly dispersed in the resin layer and that 5i02 was also exposed on the surface of the coating layer. Furthermore, when the angle of repose of the toner produced in this example was measured, it showed high fluidity of around 30°. Furthermore, when the specific resistance was measured in the same manner as in the above method, it was found that 5xlO
"0 cm, indicating sufficient electrical insulation.

(Image evaluation) The toner produced in this example was used in a single-component contact developing machine.
It was installed in a laser printer having a C photoreceptor to form an image, and the image was evaluated. As a result, the maximum allowable range of the development gap for the amount of development to be within the allowable value was 400 μm. Here, the allowable range of the amount of development is determined by the lower limit being the allowable image density, and our standard is the image temperature of 1.4 and the lower limit is 1.2.

The upper limit was determined in consideration of the occurrence of poor fixing on the recording paper due to too large an amount of development, and the fact that the number of printable sheets per unit of toner would not be significantly lower than the standard due to the increased amount of toner consumption. For these reasons, the allowable range of the amount of development was set to within 20% of the standard usage amount. Regarding the improvement of the edge effect, a 1 cm square pattern was developed and evaluated by a plurality of people who visually judged the print quality. The toner of this example had an image quality rating of 4 when evaluation was performed on a five-level scale with 1 being the lowest quality and 5 being the highest quality. (The image evaluation with the conventional two-component developing machine was 4.) Furthermore, with the toner of this example, the dependence of the image temperature on the developing voltage is almost the same for any developing gap value within the range of the allowable developing gap. Met.

Furthermore, when we conducted a durability test of 30,000 sheets, we were able to obtain clear images without any blocking or caking, just like in the early days. Furthermore, similar tests were conducted by sealing the toner produced in this example in a container and storing it in an environment of 30°C - 80% for three months, but there was no deterioration in characteristics such as aggregation, and clear images were obtained. I was able to do that.

[Comparative Example 1] Inorganic particles and resin particles were attached to the inner core particles prepared in Example 1 in the same manner as in Example 1 (attachment of inorganic particles and resin particles), and the toner without solvent treatment was used. Created. When this toner was loaded into the laser printer used in Example 1 to form an image, the toner had poor fluidity and agglomerated in the developing machine, making it impossible to form a clear image. In addition, deposits were peeled off and the inside of the developing machine was contaminated.

[Example 2] In this example, wax was the main component as the inner core particle,
Particles containing magnetic powder and a colorant were used.

In other respects, the same procedure as in Example 1 was carried out.

(Preparation of inner core particles) Paraffin wax: 30 wt% Polyethylene wax: 30 wt% Fe3O4 36 wt% Carbon black: 4 wt% The raw materials having the above composition are kneaded in a patch mixer, cooled and coarsely pulverized. Next, the mixture was finely pulverized using a jet pulverizer, and then classified to produce inner core particles with an average particle diameter of 10 μm and a distribution of 5 to 25 μm.

When the characteristics of the obtained particles were evaluated in the same manner as in Example 1, the specific resistance was 7×10 3 Ωam, and the specific rust rate was 300.

(Adhesion of inorganic fine particles and resin particles) The same PBMA and SiO2 as in Example 1 were used, and the same composition as in Example 1 was used. However, as a mechano condition,
Since the inner core particles are soft, the rotation speed was 800 rpm and the processing time was 15 minutes.

(Solvent treatment) Xylene was used as the solvent. Spray drying was carried out at a contact time of 1 second and a drying temperature of 60°C. The obtained particles are Example 1
Similarly, there was no bond between particles, and each particle was an independent aggregate.

Furthermore, when the angle of repose was measured, it was found to be 32°, indicating high fluidity. (The angle of repose of the inner core particles was 50° or more.) Furthermore, when the obtained toner was cross-sectionally observed using an electron microscope, it was found that 0.00% was observed on the surface of the inner core particles. A resin coating layer of 5 to 1.5 μm was formed. When the specific resistance was measured in the same manner as in Example 1, it was 6×10 14 Ωcm, indicating sufficient insulation.

(Image evaluation) When the toner produced in this example was loaded into a laser printer equipped with a one-component magnetic brush developer and an OPC photoconductor to form an image, no blocking or caking occurred, and the fixing temperature was 120°C. It was possible to form clear images at low temperatures.

Further, when image evaluation was performed in the same manner as in Example 1, the results were similar to those in Example 1. Furthermore, when we conducted a durability test of 30,000 sheets, we were able to obtain clear images without any blocking or caking, just like in the early days.

Furthermore, the toner produced in this example was sealed in a container, and
A similar test was carried out by storing it in an environment of -80% °C for three months, but there was no deterioration in properties such as aggregation, and clear images could be obtained.

[Comparative Example 2] An outer shell was formed on the inner core particles used in Example 2 by a spray drying method.

PBMA was dissolved and dispersed in acetone so that the solid content was 10%, the 5i02 particles 20.2 μm were 7% solid, and the core particles were 25% solid. This dispersion liquid was spray-dried using a spray dryer to produce toner particles. The spraying method uses a two-fluid nozzle, and the spraying conditions are a pressure of 2k.
g/cm2. The drying temperature was 40°C. The obtained toner particles were adjusted to 5 to 20 μm (average particle size: 11 μm) by classification, and evaluated in the same manner as in Example 1. As a result, the specific resistance was 7 x 109 Ωcm, and the angle of repose was 53''.The image quality evaluation was 2,
It was not possible to form clear images.

[Example 3] A toner was produced using the same inner core particles, inorganic fine particles Sio2, and resin particles PBMA as in Example 2, and varying the particle sizes of the inorganic fine particles and resin particles. Tables 1 and 2 show the relationship between experiment number and particle size. Table 1 shows the relationship between the experiment number and the particle size.
The particles were produced by changing the particle size of the 02 particles. Table 2 shows the SiO2 used in Example 1 as inorganic fine particles: 0.0
2 μm, and the particle size of the resin particles was changed.

Table 1 * All resin particles are PBMA: 0.4 μm Table 2 * All inorganic fine particles are 5i02: 0.02 μm Next, in the same manner as in Example 2 (attachment of inorganic fine particles and resin particles) and (
(solvent treatment). However, the contact time was changed depending on the particle size. The results of the toner made with the above material are shown in the third
Shown in the table. Furthermore, images were formed on these toners in the same manner as in Example 1, and the images were evaluated. The results are shown in Table 4.
It is shown in Table 5.

The definition of "clear" in Table 3 and Table 4 is an image with no background fog and an image temperature of 1°5 or higher.

From this example, when the particle size of the inorganic fine particles is larger than 0.1 μm and when the particle size of the resin particles is larger than 1.0 μm, the fluidity deteriorates and a clear image cannot be obtained. The matter became clear.

Table 5 As shown, when the thickness of the insulating layer was less than 0.5 μm, the electrical insulation was insufficient, development and transfer were not performed normally, the development gap was small, and the image quality was degraded.

[Example 4] Using the inner core particles of Example 1, SiO2, and PBMA particles,
SiO2! This was done by varying t. 5iO21t was calculated based on the coverage rate on the surface of the resin particles. Table 6 shows the composition.

Using these composition ratios, toners were prepared in the same manner as in Example 1 (attachment of inorganic fine particles and resin particles) and further in the same manner as in Example 1 (solvent treatment).

Images were formed using these toners in the same manner as in Example 2, and the images were evaluated. The results are shown in Table 7.

Table 6 Table 7 Note that in No. 10, severe peeling of SiO2 occurred, resulting in equipment contamination. Also, the angle of repose is 45@ for NO37 and 10,
No. 8 and 9 were 30-33a.

In this way, if the converted coverage is less than 100%, the surface exposure S
i O2 decreases and fluidity decreases. Furthermore, 200
%, it is thought that 5i02 becomes excessive and fluidity decreases.

[Example 5] The experiment was carried out by changing the inner core particles of Example 1 to the following. The rest was carried out in the same manner as in Example 1.

The composition of the inner core particle is shown below.

Oxidized polyethylene wax 4wt% paraffin wax 4wt% polyester
10 wt% Fe3O476 wt% Carbon black 4 wt% Black titanium dioxide 2 wt% However, kneading was performed using a batch type screw kneader and the mixture was ground to 10 μm. The obtained particles had a specific resistance of 8×10 13 ΩCm and a relative dielectric constant of 3. Next, carbon black was externally added to these particles using a mechanofusion system and fixed on the surface.

The conditions were carbon black fil Ow t%, mechano rotation speed 1600 rpm, and processing time 30 minutes.

The specific resistance and dielectric constant of the particles externally added with carbon black in this manner were determined by the method shown in Example 1.

As a result, the specific resistance is 2X10'Ωcm, and the specific dielectricity is 4350.
Met. Next, the particles were subjected to the (attachment of inorganic fine particles and resin particles) and (solvent treatment) in Example 1 to produce a toner. The obtained particles exhibited insulation properties of 3 x 10"0 cm. Furthermore, when an image was formed in the same manner as in Example 1, the same effect as in Example 1 was obtained.

A feature of the toner of this example is that ordinary carbon black, which is not a conductive type, can be used as a raw material in producing highly dielectric particles, which makes it possible to achieve a lower viscosity when melting the toner. can give. The toner produced in this example was printed and fixed on a paper surface, the fixing rate was measured, and the temperature at which fixing was possible was investigated. After measuring the temperature of the black solid print sample with an optical thermometer, the adhesive tape is applied and removed, the temperature of the pasted area is measured again, and the rate of temperature change before and after is calculated and this is determined as the fixation rate. did. The toner of this example had a fixing rate of 90% or more when fixed at 120° C., and it was possible to fix at a low temperature.

[Example 6] Fine particles of terephthalic acid, hexamethylene diol, glycerin as a binding material, magnetite as a colorant and magnetic material, and barium titanate as a ferroelectric material were mixed and dispersed in a colloid mill, and the resulting dispersion was obtained. was heated under reduced pressure to obtain a crosslinked polyester resin block. The composition of this block is shown below.

Polyester resin 30wt% magnetite 45wt% barium titanate
At this time, the dielectric constant of this resin block was 230. Next, the resin block is mechanically crushed to obtain crushed pieces, then dispersed in an aqueous liquid and crushed in a colloid mill, the aqueous liquid is removed, and after drying, the maximum particle size is 1 μm, the average particle size is 0.3 ~ Ferroelectric fine particles of 0.5 μm were obtained. 100wt% of these ferroelectric fine particles are mixed with 15wt% of polyester resin.
The mixture is dispersed in a batch type screw kneader. This polyester resin is a material that melts at a low temperature with a glass transition point of 40° C. Even if it contains a large amount of solid content, it has a low viscosity when melted, so it can be easily heat-fixed. The obtained kneaded product was cooled and pulverized using a jet air pulverizer, and the particle size distribution was controlled using an air classifier to obtain particles with an average particle size of 10 μm. Using the thus obtained inner core particles, a resin coating layer was formed on the surface in the same manner as in Example 1.

The specific resistance of the obtained toner was 7×10 14 Ω, indicating sufficient electrical insulation. The thus obtained toner was used in Example 1.
When image formation was evaluated in the same manner as in Example 1, the same results as in Example 1 were confirmed.

[Example 7] The average particle size obtained in Example 6 was 0.3 to 0. After preparing a solution in which 5 μm ferroelectric fine particles are uniformly dispersed in a mixed solution of styrene monomer and acrylic monomer using a colloid mill, BPO is used as a polymerization initiator to prepare a solution known in the art, such as Japanese Patent Publication No. 36-10231. The composition of styrene acrylic particles in which ferroelectric fine particles having an average particle size of 10 μm are dispersed was obtained by the suspension polymerization method disclosed in the following is shown below.

Styrene acrylic resin 15 wt% Ferroelectric fine particles 85 wt% A resin coating was formed on the surface of the inner core particles prepared by the above method in the same manner as in Example 1, and -
A component-insulating magnetic toner was prepared. The specific resistance of the obtained toner was 5×10 14 Ω, indicating sufficient electrical insulation.

When the thus obtained toner was evaluated for image formation in the same manner as in Example 1, the same results as in Example 1 were obtained.

Although the embodiments have been described above, the present invention is not limited to these embodiments, and it is also possible to add other toner components into the coating layer.

[Effects of the Invention] As described above, the toner and toner manufacturing method of the present invention have at least a two-layer structure, the outermost shell layer exhibits electrical insulation, and the internal effective dielectric constant In a toner having a dielectric constant higher than that of the outermost shell, a resin coating layer is formed using inorganic fine particles and resin particles on the outer surface of the inner core particles, and the inorganic fine particles are exposed inside and on the outer surface of the coating layer.
Furthermore, the toner of the present invention can be prepared by dry-adhering mixed particles of inorganic fine particles and resin particles, and then treating with a solvent that dissolves the resin particles, so that the toner has almost no agglomeration and has excellent fluidity. It is possible to obtain a toner having a dielectric constant of . As a result, in the -component development system, it becomes possible to obtain excellent image quality with less development gap dependence and less edge effect than before. Furthermore, since the inorganic fine particles fixed to the toner surface do not come off, there is no contamination within the device, and since the toner charge amount does not change over time and is stable, the image quality is always clear. Further, according to the manufacturing method of the present invention, it is possible to uniformly and easily control the thickness of the coating layer made of various resin components and inorganic components, thereby easily producing a toner that satisfies the above characteristics. Therefore, the toner and toner manufacturing method of the present invention can greatly contribute to reducing the cost of manufacturing toner having a desired dielectric constant, and furthermore, the mechanical precision required for the developing section of an image forming apparatus can be reduced. This has an extremely large effect in that it can contribute to cost reduction of image forming apparatuses.

By applying the present invention, it becomes possible to realize low-cost compact electrophotographic printers, low-cost compact electrophotographic copying machines, low-cost compact facsimile machines, etc. Also, since precision regulations are loose, large-sized image forming devices, such as low-cost large-format It can also be applied to CAD output devices, large image displays, etc., and its application fields are extremely wide.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of the most characteristic toner manufacturing method of the toner of the present invention. FIG. 2 is a cross-sectional view showing the structure of the base particles of the toner of the present invention. FIG. 3 is a cross-sectional view showing the structure of a film-treated product that is a characteristic feature of the toner of the present invention. Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Kizobe Suzuki (1 person) Figure 2 Figure 3

Claims (5)

[Claims] (1) Consists of at least a binder resin and a colorant, has at least a two-layer structure, the outermost shell layer exhibits electrical insulation, and the internal effective dielectric constant is the dielectric constant of the outermost shell layer. A toner characterized in that a resin coating layer is formed on the outer surface of inner core particles using inorganic fine particles and resin fine particles. (2) The toner according to claim 1, wherein in the resin coating layer containing inorganic fine particles according to claim 1, the inorganic fine particles are exposed on the inner and outer surfaces of the coating layer. (3) Adhering mixed particles of inorganic particles with a particle size of 0.1 μm or less and resin particles with a particle size of 1 μm or less to the outer surface of the inner core particles, and then treating with a solvent that dissolves the resin particles. A toner manufacturing method comprising forming a resin coating layer containing inorganic fine particles. (4) The content of the inorganic fine particles contained in the coating layer is 100 or more in terms of the coverage rate of the inorganic fine particles on the surface of the resin fine particles.
4. The toner manufacturing method according to claim 3, wherein the toner manufacturing method is within a range of 200%. (5) The toner manufacturing method according to claim 3, wherein the adhesion of the mixed particles of inorganic fine particles and resin fine particles to the surface of the inner core particles is carried out in a dry manner.