JPH04182669A - Production of toner for electrophotography - Google Patents

Abstract

PURPOSE:To enable production of a toner for electrophotography which satisfies the electrophotographic characteristics such as fluidity, chargeability, etc., by depositing at least resin fine particles on the surface of inner core particles and treating the resin particles with a mixture solvent comprising a solvent which dissolves the resin and functioning agent and/or mold releasing agent added thereto. CONSTITUTION:The toner inner core 1 consists of a binder resin 2, colorant 3, magnetic powder 4, etc., and is produced by general kneading and pulverizing method to have 1 - 40 mum particle size. The core may be spherical or amorphous. The mold releasing fine particles 7 are wax, higher fatty acids, or the like. As for the charge controlling agent, electron accepting org. complex, chlorinated polyester, or nitrohumic acid may be added. The fine particles are deposited on the surface of the inner core particles by wet method such as spray drying surface precipitation method, or by dry method such as mechanochemical method, etc. The solvent to be used to treat the core particles with deposition of resin fine particles is decided according to the physical properties of the core particles and fine particles. Therefore, water or org. solvent is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing electrophotographic toner for use in printers, copiers, facsimile machines, and the like. More specifically, the present invention relates to a method of producing a toner with improved anti-offset properties.

[Prior Art] In image forming apparatuses using electrophotographic toner, heat roller fixing is the mainstream method for forming a permanent image on recording paper. However, this method has the disadvantage that a portion of the toner is fused to the roller surface and transferred onto the recording paper again, which tends to cause an offset phenomenon that stains the image.

Conventional methods for preventing this offset include forming the roller surface with a material with relatively good releasability and coating the surface with a liquid such as silicone oil, and broadening the molecular weight distribution of the toner binder resin ( JP-A-5O-1364
25), a method in which a releasing agent is added to the toner to give the toner itself moldability (Japanese Patent Publication No. 52-3304).

[Problems to be Solved by the Invention] However, in the conventional method using silicone oil or the like, the apparatus becomes complicated and oil needs to be replenished, making it expensive. Furthermore, when the molecular weight distribution is broadened and the high molecular weight component is increased, the softening point becomes high, which increases power consumption and impairs the durability of the fixing device. Increasing the amount of low molecular weight components is effective in lowering the softening point, but at the same time the glass transition point also decreases, resulting in poor toner storage stability. Therefore, it has been difficult to obtain a toner that simultaneously satisfies the properties of maintaining good fixability.

Adding a release agent to the toner to give the toner itself release properties is a simple method, but in order to obtain a sufficient effect on offset resistance, it is necessary to include a large amount of the release agent. If this happens, the storage stability of the toner will be poor, and since these mold release agents have poor compatibility with the binder resin, the toner composition will become non-uniform and this will adversely affect the development characteristics such as charging properties. Ta.

Therefore, an object of the present invention is to solve the above-mentioned problems, and its purpose is to improve fixing performance and improve fixing performance without complicating the device.
An object of the present invention is to provide a method for producing an electrophotographic toner that can ensure offset resistance.

A further object of the present invention is to provide a method for producing an electrophotographic toner that satisfies electrophotographic properties such as fluidity and chargeability without complicating the production process.

[Means for Solving the Problems] The method for producing an electrophotographic toner of the present invention includes a step of attaching at least fine resin particles to the surface of the inner core particles, and adding at least a functional agent and/or a release agent to a solvent for dissolving the fine resin particles. The method is characterized by comprising a step of treating the particles with a mixed solvent to which is added, and a step of drying and collecting the treated particles.

[Action] By mixing large-diameter mother particles and small-diameter child particles and processing them through mechanochemical reactions, the child particles have electrostatic force, chemical adsorption force, and physical adsorption on the surface of the mother particle. Adheres uniformly due to force, etc. When fine resin particles are attached as child particles, the resin is dissolved by bringing a solvent that dissolves the resin particles into contact with the fine resin particles, and a film made of the resin component is formed on the surface of the mother particle.

If the manufacturing method is followed by mixing mold release agent particles with small particles during the mechanochemical reaction, a coating layer in which the mold release agent is dispersed is formed on the surface of the base particles.

Furthermore, by treating the resin particles by mixing a fluidity improver, a charge control agent, and other functional agents in a solvent that dissolves the resin particles, a toner with these functional agents fixed in the coating layer can be created at once. It becomes possible to do so.

When an image is formed using the above-mentioned toner, the surface of the toner that comes into contact with the roller during fixing is not fused due to the action of the release agent, thereby preventing the offset phenomenon. Furthermore, since the release agent is added only to the surface of the toner, its content relative to the entire toner is small and can prevent agglomeration during storage.

Hereinafter, the present invention will be described in detail based on the drawings, but it goes without saying that the present invention is not limited thereto.

[Example] FIG. 1 shows a cross-sectional view of the electrophotographic toner of the present invention. The toner inner core 1 consists of a binder resin 2, a colorant 3, a magnetic powder 4, etc., and these inner core particles have a particle size of 1 to 40 μm and are prepared by a general kneading and pulverization method, spray drying method, or polymerization method. do. The shape may be spherical or irregular.

As the binder resin 2, polystyrene and copolymers such as hydrogenated styrene resin, styrene/isobutylene copolymer, ABS resin, ASA resin, AS resin, AAS resin, AC3 resin, ABS resin, styrene/P-chlorostyrene copolymer, etc. Polymer, 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 and its copolymer, For example, styrene/acrylic copolymer, styrene/diethylamino/ethyl methacrylate copolymer, styrene/butadiene/acrylic 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 Acrylate 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, styrene/n-butyl methacrylate/acrylic acid copolymer, styrene/n-butyl methacrylate・Maleic anhydride copolymer, styrene/butyl acrylate/isobutyl maleic acid half ester/divinylbenzene copolymer, polyester and its copolymer, polyethylene and its copolymer, epoxy resin, silicone resin, polypropylene and its copolymer One type or a blend of two or more types of resins such as fluorine resin, polyamide resin, polyvinyl alcohol resin, polyurethane resin, and polyvinyl butyral resin can be used. Moreover, wax etc. can also be used as a substance other than resin. For example, plant-based natural waxes such as candelilla wax, carnauba wax, and rice wax, animal-based natural waxes such as beeswax and lanolin, mineral-based natural waxes such as montan wax and osikelite, and natural natural waxes such as paraffin wax, microcrystalline wax, and petrolatum. Petroleum wax, polyethylene wax, Fisher wax
Synthetic hydrocarbon Fuchs 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, and higher fatty acids such as stearic acid and valmitic acid. , polyolefins such as low molecular weight polyethylene, polyethylene oxide, and polypropylene, and one or more olefin copolymers such as ethylene/acrylic acid copolymers, ethylene/acrylic acid ester copolymers, ethylene/vinyl acetate copolymers, etc. use

As the coloring agent 3, a black dye/pigment such as carbon black, spirit black, or nigrosine is 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.

As the magnetic powder 4, Fe3O4, Fe2O3, Fe, O
r, Ni, etc. are used.

The coating layer 5 consists of a binder resin 6, releasable fine particles 7, and, if necessary, a charge control agent and a fluidizing agent.

The binding resin fine particles 6 include polymethyl methacrylate (PMMA), polyethyl methacrylate, polybutyl methacrylate (PBMA), polyester,
(styrene-butadiene) copolymer, (PVC, PV
A, PVAc) Near polymer, poly γ-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.

As the releasable fine particles 7, the same waxes, higher fatty acids, and olefin polymers mentioned in the binder resin are used.

Charge control agents (hereinafter referred to as OCA) include electron-accepting organic complexes, chlorinated polyesters, nitrofnic acid, quaternary
Grade ammonium salts, pyridinyl salts, etc. can be added.

As the fluidizing agent, fine powders of oxides such as 5in2, TiO2, (rutile, anatase), and Zn○, and fine powders of fluororesins such as polyvinylidene fluoride are used.

FIG. 2 shows a flowchart of the method for producing an electrophotographic toner of the present invention.

As a method for adhering and externally adding fine particles to the surface of the inner core particles, wet methods such as spray drying, interfacial precipitation, Peter flocculation, and wet milling, and dry methods such as mechanochemical methods are possible.

In the case of a dry method, a conventional mixer such as a ball mill or a V-type mixer can be used, but it is preferable to use a so-called high-speed fluidized stirrer to carry out the mechanochemical reaction. Examples of high-speed fluidized stirrers include the so-called Henschel mixer, Mechano Fusion System (Kishu Micron),
Nara Hybridization System (Nara Kikai Seisakusho), Mechano Mill (Kaida Seiko), etc. are used. However, as a device for attaching fine particles to the surface of the inner core particles,
It is not limited to these. Next, methods for treating the solvent include spray drying, immersion, and the like, but any method may be used as long as the contact time can be controlled. Preferably, a powder coating device, such as Disper Coat (Nissin Seifun) or Coat Mizer (Freund Sangyo), is used.

The solvent used to treat particles with fine resin particles attached to the surface of the inner core particles is determined depending on the materials of the inner core particles and the fine particles. For this reason, water-based, organic solvent-based, etc. can be used. For example, organic solvents include halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, and chlorobenzene, alcohols such as methanol, methyl cellosolve, and benzyl alcohol, and ethers such as dioxane, tetrahydrofuran, and benzyl ether. Esters such as ethyl acetate and butyl acetate, ketones such as furfural, acetone, methyl ethyl ketone, and cyclohexane, aromatics such as benzene, toluene, and xylene, and nitrogen compounds such as nitrobenzene, acetonitrile, diethylamine, aniline, dimethylformamide, and pyrrolidone. Can be used.

This example will be explained in more detail below.

[Example 1] (Preparation of inner core particles) Styrene-acrylic copolymer 97 parts by weight Metal-containing azo dye 1 part by weight Carbon black 2 parts by weight Using the raw materials of the above composition, kneading with a twin-screw extruder, cooling and coarsely pulverizing. do.

Next, after finely pulverizing with a jet pulverizer, it is classified to have an average particle size of 1
Inner core particles with a diameter of 0 μm and a distribution of 5 to 25 μm were prepared.

(External Addition of Fine Particles) Polypropylene wax particles (hereinafter referred to as P P Wax) were used to prevent offset.

PBMA 60 parts by weight P
P Wa x 40 parts by weight PBMA used had a particle size of 0.4 μm and a glass transition point of 83°C. These fine particles and the inner core particles are mixed in the composition shown below, and the externally added fine particles are attached to the surface of the inner core particles using a Mechano Fusion System (manufactured by Kishu Micron) (hereinafter referred to as mechano treatment). The composition and conditions are shown below.

Inner core particles 80wt% externally added fine particles
As a 20wt% mechano condition, the rotation speed is 15
The treatment was carried out at 0 rpm and for 30 minutes. Excess fine particles that did not contribute to adhesion of the obtained powder particles were removed using a classifier. (Removal of excess particles using a classifier can be omitted by adjusting the amount of externally added fine particles.) However, even after removal, PBMA particles and PPW a x
Electron microscopic observation of the surface revealed that the particles did not peel off but were attached to the surface of the inner core particle. In addition, when cross-sectional observation was performed using an electron microscope, the inner core particle table ml showed
It was observed that the PBMA particles and PPWaX particles remained spherical and attached to the outside.

(Solvent Treatment) The inner core particles to which the fine particles prepared by the above method were externally added were subjected to a solvent treatment using a powder coating device. As a solvent, A7Tone, which dissolves PBMA particles, was used, and as a functional agent, the following materials were used.

OCA... 5 parts by weight 5i
02: 5 parts by weight Acetone: 90 parts by weight The air flow pressure, powder and solvent supply amounts were adjusted so that the amount of each component transported was 1 kg/hr for both the powder and the mixed solution. After these were brought into contact and mixed, the mixture was spray-dried, and the resulting toner was collected using a cyclone.

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, a 0.2 μm coating layer was formed on the surface of the inner core particle, and the coating layer contained microparticles believed to be OCA and 5i02. existence confirmed.

Using the toner prepared above, an image was formed by installing it in a laser printer having a -component non-contact developing device and an OPC photoreceptor. The surface of the heat fixing roller was made of fluorocarbon resin. As a result, it was confirmed that a clear image was formed at a printing speed of 20 PPM, and the O and D values of the 0 image were secured at 1°2 to 1.5. Good printing was obtained with good reproducibility. The image also shows the surface temperature of the heat roller at 140
It was found that good fixing was possible without offset in the range of .degree. C. to 200.degree. Furthermore, this toner for electrophotography does not aggregate even when left in a constant temperature and humidity bath at a temperature of 50° C. and a humidity of 60% for 10 days, and has good storage stability. This result shows that PPWax is present near the toner surface and has a sufficient release effect from the roller, and because the content is small and the wax component is protected by resin, the electrophotographic properties and storage stability are initially improved. This shows that it is as designed.

This has made it possible to produce a microcapsule toner that can maintain sufficient toner properties such as fluidity and chargeability without post-processing.

[Example 2] Multi-stage mechano processing of inner core particles is possible. In this example, P P Wa x was first laminated, and then fine resin particles were attached to form a multilayer structure consisting of uniform layers. The powder particles were subjected to solvent treatment using the same mixed solvent mainly containing acetone as in Example 1 to produce a microcapsule toner. Since PPW a x is insoluble in acetone, the cross section t! ! Upon inspection, it was confirmed that the resin layer was coated to guard against P P Wa x .

When a printing test was conducted using the toner prepared above, a good image was formed without offset.

Furthermore, even in repeated tests, almost no image staining was observed.

[Example 3] In this example, fine resin particles were attached to the inner core particles by a mechanochemical method, and PP Wax was used in the subsequent solvent treatment step.
A microcapsule toner was prepared using a resin solution in which a functional imparting agent was dispersed.

The composition of the resin solution is shown below.

Acrylic resin...9 parts by weight P,
P W ax ... 9 parts by weight OCA ... 1 part by weight 5i
02: 1 part by weight Acetone: 80 parts by weight A mixed solution having the above composition was prepared, and a microcapsule toner was produced using the same apparatus as in Example 1. In addition, the amount of powder and dispersion solution transported by high-speed airflow using compressed air at this time was 1 kg.
The air flow pressure, powder, and solvent supply amounts were adjusted so that When a printing test was conducted using the toner produced by this method, good printing was possible without offset.

[Example 4] In Example 3, P was treated with an acrylic resin solution as a binder for the mold release agent, but P
It is possible to fix P W a X. The inner core particles of Example 3 were subjected to solvent treatment using a mixed solvent having the following composition.

PPWax ---10 weight 1 part OC
A... 5 parts by weight 5i02
... 5 parts 1 part acetone
...1 part of 80 weight When a printing test was conducted using the toner obtained in this example, good printing was possible without offset.

[Example 5] In this example, fine resin particles and a charge control agent as a functional material are attached to the inner core particles by a mechanochemical method, and P P Wa x and a fluidizing agent are added to the resin in the subsequent solvent treatment step. A microcapsule toner was prepared using the particles dispersed in a solution.

[Example 6] Fine resin particles and a fluidizing agent were added as processing agents for the inner core particles, and P P W a x and charge l! were added to the solvent treatment step.
A microcapsule toner was prepared using an il control agent dispersed in a resin solution.

[Example 7] Resin fine particles and a charge control agent and a fluidizing agent were used as functional agents in the external addition treatment of the inner core particles, and p p was added in the solvent treatment step.
A microcapsule toner was prepared using wax dispersed in a resin solution.

When a printing test was conducted using the toners of Examples 5 to 7, good printing was possible without offset. [Example 8] Using the same apparatus and inner core particles as in Example 1, outer core particles were injected into the inner core particles. The thickness of the coating layer was controlled by changing the particle size of the added fine particles. The resin fine particles have a particle size of 0°4 μm (PBMA),
Particle size 0.8 μm (PMMA), particle size 1.0 μm (P
MMA) was used. Table 1 shows the conditions for external addition of fine particles. Next, these particles were treated with a solvent in the same manner as in Example 1. As in Example 1, the particle surface and cross section of the obtained particles were observed using an electron microscope, and the film thickness was measured.

Table 2 shows the treatment conditions and results. By changing the particle size of the particles attached to the surface of the inner core particles in this manner, a coating layer having an arbitrary thickness can be formed.

Table 1 *Processing time: All treatments were performed in 30 minutes.

Table 2 *Solvent: Acetone Although examples of the present invention have been shown above, the method for producing an electrophotographic toner of the present invention is not limited to these examples, and a release agent may be added to the coating layer. It is possible to apply this method to all toners with this configuration.

[Effects of the Invention] As described above, according to the method for producing an electrophotographic toner of the present invention, the step of attaching at least resin fine particles to the surface of the inner core particles, the step of attaching at least a functionalizing agent and/or to the solvent for dissolving the resin fine particles. Alternatively, it consists of a process of treating with a mixed solvent containing a release agent, and a process of drying and collecting the treated particles, so that the release agent and functionality can be applied uniformly over the entire circumference of the toner and in a small amount added to the toner. It has become possible to produce toner containing a imparting agent. This has made it possible to have sufficient toner properties and to perform good printing without offset. The toner for electrophotography according to the present invention can be applied to copiers, fax machines, printers, etc., and if the method for manufacturing the toner for electrophotography according to the present invention is used, the toner has good storage stability and can be used in repeated image formation. This has the great effect of making it possible to easily produce toner that can print with stable quality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a cross section of the electrophotographic toner of the present invention. FIG. 2 is a diagram showing a flowchart of an example of the method for manufacturing an electrophotographic toner of the present invention. Applicant: Seiko Epson Corporation

Claims (1)

[Claims] (1) In a method for producing a microcapsule type electrophotographic toner containing a release agent as a constituent of the coating layer, the step of attaching at least resin fine particles to the surface of the inner core particles, the step of attaching at least a functionalizing agent to a solvent for dissolving the resin fine particles; A method for producing an electrophotographic toner, comprising the steps of treating with a mixed solvent added with/or a release agent, and drying and collecting the treated particles.