JPH04120552A - Toner for electrophotography and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic toner for visualizing an electrostatic image formed on a dielectric material, and a method for manufacturing the same.

[Prior Art] The toner used in conventional electrophotography and its manufacturing method are known as the Carlson process (U.S. Pat. No. 2,297,699).
Based on 1), a pulverization method has been proposed in which a thermoplastic resin and a coloring material are melted and kneaded and then finely pulverized.
2666), resin fine powder coated toner (JP-A-1-10
5261), polymerized microcapsule toner (Tokuko Sho 5)
9-31066, Japanese Patent Publication No. 62-61141), etc. have been proposed.

[Problems to be Solved by the Invention] However, in the toner produced by the conventional electrophotographic toner manufacturing method, the method of fixing the coating layer to the toner uses high-speed collision force or impact force (Japanese Patent Application Laid-Open No. 63-62666,
In JP-A-1-105261), the adhesion between the toner surface and the coating layer is weak, and the thickness and adhesion of the coating layer vary widely, so when used in an electrophotographic image forming apparatus, it deteriorates and the toner surface deteriorates. There were problems in that image quality deteriorated due to peeling off from the surface, changes in surface shape, etc.

In addition, a coating method using the microcapsule method
31066 (Japanese Patent Publication No. 62-61141) also had similar problems, such as the thin coating layer thickness and large variations in toner stability, such as durability and cohesiveness of the toner.

The present invention is intended to solve these problems, and its purpose is to form a resin coating layer on the surface of an electrophotographic toner that has a uniform coating layer thickness and is strongly adhered to the toner surface. Another object of the present invention is to provide an electrophotographic toner with improved stability when used in an electrophotographic image forming apparatus, and a method for producing the same.

[Means for Solving the Problems] The electrophotographic toner of the present invention is an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material.
A first resin and a second resin in a resin particle-dispersed resin solution in which resin particles made of a first resin are dispersed on the surface of a toner inner core, which is a main component of an electrophotographic toner, and a second resin is dissolved therein. A resin coating layer made of resin is formed.

The method for producing an electrophotographic toner of the present invention is a method for producing an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material. a step of preparing a toner inner core in a resin particle-dispersed resin solution in which resin particles made of a first resin are dispersed and a second resin dissolved therein; and resin particles made of the first resin and the second resin are added to the toner inner core, resin particles made of the first resin, and resin particles made of the second resin on the surface of the toner inner core by adding a solvent in which none of the toner inner core, the resin particles made of the first resin, and the second resin are soluble. The present invention is characterized by comprising a step of forming an adhesion layer and a step of dissolving the resin particle adhesion layer to form a resin coating layer composed of a first resin and a second resin on the surface of the toner inner core.

[Function] The electrophotographic toner of the present invention comprises resin particles in which resin particles made of a first resin are dispersed on the surface of the inner core of the toner, which is the main component of the electrophotographic toner, and a second resin is dissolved therein. A resin coating layer is formed of a first resin and a second resin in a dispersed resin solution. It is possible to control the layer thickness. Resin particles are created by emulsion polymerization, suspension polymerization, etc., but resin particles created by emulsifier-free emulsion polymerization, seed polymerization, and dispersion polymerization, which are improved methods of emulsion polymerization, have particularly poor particle size distribution. It is very narrow, and when used in the manufacturing method of the present invention, the variation in the thickness of the coating layer becomes very small. The adhesion of the resin particles to the inner core of the toner is achieved by dispersing the resin particles made of the first resin and dissolving the second resin in a resin solution in which the resin particles are dispersed.
This is done by adding a solvent in which the resin is insoluble and co-precipitating resin particles made of the first resin during a so-called interfacial precipitation phenomenon in which the second resin is precipitated on the surface of the inner core of the toner. In the resulting second resin precipitate layer, the first
A resin particle adhesion layer containing resin particles made of resin is formed. Furthermore, since the second resin precipitate layer is a thin film of approximately several tens of nanometers, the thickness of the resin particle adhesion layer is approximately the same as the particle diameter of the resin particles. Furthermore, by dissolving the resin particle adhesion layer with a solvent, a resin coating layer containing a mixture of the first resin and the second resin is formed on the surface of the inner core of the toner, and the thickness of the coating layer formed by this method changes during the dissolution operation. Since there is no addition or removal of substances during the process, it is determined by the particle size of the resin particles used and the amount of adhesion on the surface of the inner core of the toner.

The details of the present invention will be shown below with reference to Examples.

[Example code] FIG. 1 is a sectional view of the electrophotographic toner of the present invention.

The toner inner core 1 is the main component of the toner for electrophotography,
It is composed of a binder resin 2, a coloring agent 3, a magnetic powder 4, and a mold release agent 5.
Produced by a wet method such as the microcapsule method.

The binder resin 2 includes olefin polymers such as polyethylene, polypropylene, polybutylene, polyisobutylene, and polymethylpentene, vinyl ester derivative polymers such as polyvinyl acetate, vinyl polypropionate, and vinyl polyamylate, polymethyl acrylate, and polymethyl acrylate. ethyl acrylate,
Propyl polyacrylate, butyl polyacrylate, octyl polyacrylate, dodecyl polyacrylate, stearyl polyacrylate, phenyl polyacrylate, benzyl polyacrylate, polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, Polymers of carboxylic acid ester derivatives such as polybutyl methacrylate, polyoctyl methacrylate, polydodecyl methacrylate, polystearyl methacrylate, polyphenyl methacrylate, polybenzyl methacrylate, polyethylhexyl methacrylate, polydiethylaminoethyl methacrylate, etc. Acrylate and methacrylate derivative polymers such as acrylonitrile, polyacrylonitrile, polyacrylamide, styrene derivative polymers such as polystyrene, poly-α-alkylstyrene, poly-β-alkylstyrene, polydivinylbenzene, polyvinyl methyl ether, polyvinyl ether, Addition polymers such as vinyl ether polymers such as polyvinylpro and polyether, vinyl ketone polymers such as polyvinyl methyl ketone, polyvinyl methyl ethyl ketone, and polyvinyl propyl ketone, nitrogen-containing vinyl derivative polymers such as polyvinyl pyrrolidone and polyvinylindole, and 2 of these. Copolymers, crosslinked products, mixtures of more than one species, and condensation of polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6 and nylon 66, polycarbonate resins, polyarylate resins, polyurethane resins, etc. Polymers, copolymers, crosslinked products, mixtures of two or more of these, and cellulose derivative resins such as cellulose resins are used alone or in combination.

Furthermore, if the purpose is to fix at low temperatures, vegetable waxes such as candelilla wax and carnauba wax, animal waxes such as beeswax and lanolin, mineral waxes such as montan wax, paraffin wax, microcrystalline wax, etc. Synthetic hydrocarbon waxes such as petroleum waxes, polyethylene waxes and Fischer-Trops waxes, modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, fatty acids, acid amides, esters, Waxes such as synthetic waxes such as ketones are used, and the coloring agent 3 used is a mixture of a single second or a plurality of waxes, and a resin component, such as benzidine yellow disazo yellow for yellow color, carmine 6B, and carmine 6B for red color. Facial dyes such as Lake Red C, pigment scarlet, quinacridone, phthalocyanine blue industhrene blue for blue colors, and carbon blacks such as furnace black, lamp black, acetylene black, and channel black are used for black colors.

Magnetic powder 4 is ferrite, magnetite, iron, chromium,
A fine powder made of a magnetic material such as nickel is used and is added only when a developing method using magnetic force is used.

The release agent 5 is used to prevent electrophotographic toner from adhering to a heat roller when fixing it to an image forming object such as paper or a sheet for an overhead projector, and is intended for fixing at low temperatures. The same waxes as those added in the case of , and polyethylene and polypropylene waxes are added.

The resin coating layer 6 is formed from a first resin and a second resin in a resin solution in which resin particles made of a first resin and resin particles made of a second resin are dispersed.

The charge control agent 7 and the fluidizing agent 8 are added externally after the resin coating layer 6 is formed, and as the charge control agent 7, a nigrosine type, a metal-containing dye type, a polymer electrolyte type, etc. are used. The fluidizing agent 8 is
Fine powders of oxides such as silicon oxide, titanium oxide, and zinc oxide, fine powders of fluororesins such as polyvinylidene fluoride, and the like are used.

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

The resin particles 11 made of the first resin are polyacrylate derivatives, polymethacrylate derivatives, polystyrene derivatives, polyethylene , polypropylene, polyvinyl acetate, and copolymers thereof, or spray-dried fine powder particles of polyester resin, cellulose resin, butyral resin, etc. are used. The particle size of the resin particles is adjusted to an arbitrary particle size of 0.1 μm to 3 μm, and is adjusted depending on the thickness of the resin coating layer.

As the second resin, the same resin as the resin used for the toner inner core can be used, but other resins include polyvinyl alcohol, polyallyl alcohol, polybenzyl alcohol, poly-2-hydroxyethyl methacrylate, and polyvinylpyrrolidone. , polyvinylpyridine, polyvinylamine, polyallylamine, polyacrylamide,
Water-soluble, polar solvents such as polyvinyl acrylic acid, polyvinyl methacrylic acid, polyvinyl sulfate, polylactic acid, casein, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, starch, gum arabic, polyglutamic acid, polyaspartic acid, water-soluble nylon resin, etc. It is also possible to use soluble resins, elastomers such as isoprene rubber, butyl rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-vinyl acetate elastomer.

The step of preparing a resin particle-dispersed resin solution by dispersing resin particles 11 made of the first resin and the second resin 12 in a solvent does not dissolve the resin particles 11 made of the first resin, and the second resin 12 is dispersed in a solvent. This is carried out using a solvent that dissolves the resin 12, and examples of the solvent include petroleum solvents such as hexane, heptane, and isoperkerosene, halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, and chlorobenzene, methanol, Alcohols such as methyl cellosolve and benzyl alcohol, ethers such as dioxane, tetrahydrofuran and pencil ether, esters such as ethyl acetate and butyl acetate, ketones such as furfural, acetone, methine ethyl ketone and cyclohexanone, benzene, toluene , aromatics such as xylene, nitrogen compounds such as nitrobenzene, acetonitrile, diethylamine, aniline, dimethylformamide, and pyrrolidone, and water, which may be used alone or in combination to adjust solubility. Further, the resin particles produced by the polymerization method can also be used as a resin particle-dispersed resin solution by dissolving a second resin in the resin particle dispersion after polymerization.

The toner inner core 1 is mixed and dispersed in a resin solution containing resin particles dispersed therein (14), and a precipitation solvent 15 is further added to cause interfacial precipitation (16), thereby producing a resin particle-attached toner 17.

The precipitation solvent 15 is a solvent that is soluble in the resin particle-dispersed resin solution and insoluble in the toner inner core 1, the resin particles 11 made of the first resin, and the second resin 12, such as hexane, heptane, isopar kerosene, etc. petroleum solvents, dichloromethane, chloroform, carbon tetrachloride, dichloroethane,
Halogenated hydrocarbons such as chlorobenzene, alcohols such as methanol, methyl cellosolve, benzyl alcohol, ethers such as dioxane, tetrahydrofuran, pencil ether, etc., esters such as ethyl acetate, butyl acetate, furfural, acetone, methine ethyl A solvent that meets the conditions is used, including ketones such as ketones and cyclohexanone, aromatics such as benzene, toluene, and xylene, nitrogen compounds such as nitrobenzene, acetonitrile, diethylamine, aniline, dimethylformamide, and pyrrolidone, and water. Furthermore, it is also possible to mix and use a plurality of solvents in order to adjust the solubility and precipitation rate.

The resin particle-attached toner 17 is dissolved into a film 19 by dissolving the resin particles made of the first resin and the resin particle adhesion layer made of the second resin on the surface of the inner core of the toner using a dissolving solvent 18 to obtain the resin-coated toner 20 .

As the dissolving solvent 18, a solvent in which at least the first resin is soluble is used from among the solvents that can be used as the precipitation solvent 15.

The dissolving film formation 19 is performed by steam treatment, solvent mist treatment, etc. of the dissolving solvent 18 to combine the powder (resin particle-adhered toner 17) and the solvent.
This is possible by using a method and apparatus that can form a dry film through contact in a short time of 0 seconds or less.

The resin-coated toner 20 is subjected to an external addition process 21 of a charge control agent and a fluidizing agent as required to obtain an electrophotographic toner 22.

[Example 1] Binder resin polyester resin 53 g Colorant channel black 4 g Magnetic powder Fe3O 440 g Mold release agent polypropylene wax 3 g The above was mixed and kneaded using a batch kneader, and pulverized into fine particles of 10 to 15 μm using a jet mill. A toner inner core was prepared.

Butyral resin 30 g Methyl methacrylate resin particles (particle size 0.5 μm) 50 g
Ethanol IL The above ingredients were mixed to prepare an ethanol solution of resin particles (methyl methacrylate) dispersed resin (butyral resin).

The entire amount of toner inner core is mixed and dispersed in a resin solution in which resin particles are dispersed.
2.5 L of methanol was added as a precipitation solvent over 8 hours with stirring, and the mixture was further stirred for 10 hours to perform interfacial precipitation, and unattached butyral resin was removed by filtration to prepare a resin particle-attached toner.

The methanol dispersion of the resin particle-attached toner was discharged from a two-fluid nozzle to form primary particles, which was then brought into contact with xylene mist as a dissolving solvent and mixed to replace it with methanol and form a dissolving film, thereby producing a resin-coated toner. .

Further, 2 g of silicon oxide as a fluidizing agent and 5 g of a metal-containing dye as a charge control agent were added externally, and a classification process was performed to remove unattached portions and excess resin particles to prepare an electrophotographic toner. This is referred to as "toner 1".

[Example 2] Binder resin polyester resin 53 g Colorant channel black 4 g Magnetic powder Fe3O 440 g Mold release agent polypropylene wax 3 g The above was mixed and kneaded using a batch kneader, and pulverized into fine particles of 10 to 15 μm using a jet mill. A toner inner core was prepared.

Polymethylpen-tene 30 g Styrene-methyl methacrylate resin particles (particle size 0.5 μm
) 50 g cyclohexane
IL The above ingredients were mixed to prepare a cyclohexane solution of resin particles (styrene-methyl methacrylate) dispersed resin (polymethylpentene).

The entire amount of toner inner core is mixed and dispersed in a resin solution in which resin particles are dispersed.
Add 3 L of an ether-methanol mixed solvent as a precipitation solvent over 10 hours with stirring, perform interfacial precipitation by stirring for a further 5 hours, and remove unattached polymethylpentene by filtration to create a resin particle-attached toner. did.

A methanol dispersion of toner with resin particles attached is discharged from a two-fluid nozzle to form primary particles, and is then brought into contact with and mixed with a mist of dimethylformamide as a dissolving solvent to replace it with methanol and form a dissolved film to produce a resin-coated toner. did.

Further, 2 g of silicon oxide as a fluidizing agent and 5 g of a metal-containing dye as a charge control agent were added externally, and a classification process was performed to remove unattached portions and excess resin particles to prepare an electrophotographic toner. This will be referred to as "toner 2".

[Comparative Example 1] Binder resin polyester resin 53 g Colorant channel black 4 g Magnetic powder Fe3O 440 g Mold release agent polypropylene wax 3 g The above was mixed and kneaded using a batch kneader, and pulverized into fine particles of 10 to 15 μm using a jet mill. A toner inner core was prepared.

Methyl methacrylate resin particles (particle size 0.5 μm) 30 g based on the total amount of toner inner core
were mixed and subjected to adhesion treatment using a mechanochemical method in a ball mill, followed by external addition treatment of 2 g of silicon oxide as a fluidizing agent and 5 g of metal-containing dye as a charge control agent, and classification treatment to remove unattached components. A toner for electrophotography was prepared. This will be referred to as "toner 3."

[Comparative Example 2] Binder resin styrene monomer 22 gn-butyl methacrylate monomer Colorant Channel black magnetic powder Fe50+ Mold release agent Polypropylene wax 3g Polymerization initiator Benzoyl peroxide 40mg The above total amounts were mixed and dispersed, and a dispersion stabilizer and capsule coating were prepared. In addition to carboxymethylcellulose-hydroxypropylocellulose 3% aqueous solution L as a resin solution, a toner inner core was prepared by suspension polymerization and spray drying, and silicon oxide was added as a fluidizing agent.
2 g was subjected to external addition treatment and classification treatment to remove unattached components to produce an electrophotographic toner. This will be referred to as "toner 4."

Table 1 shows the results of cross-sectional B observation of the electrophotographic toners of Example 1.2 and Comparative Example 1.2 using a transmission electron microscope to determine the thickness of the resin coating layer.

Table 1 As shown in Table 1, the electrophotographic toners "Toner 1" and "Toner 2" in the examples of the present invention have a higher resin coating layer film than the electrophotographic toner "Toner 3" in the comparative example. Variations in thickness were small, and a uniform coating layer was formed all around the toner. Compared to this, “Toner 3
'', there is uneven adhesion of resin particles and large variations in film thickness.

"Toner 4" has a film thickness of 0.02 μm or less, which is very thin compared to other toners.

In addition, the image forming unit when the electrophotographic toner of the present invention is used in a one-component magnetic developer and the image forming body is printed before and after the developer is driven and stirred for 15 hours without printing. Table 2 shows the measurement results of the optical reflection density of the non-image forming area.

As shown in Table 2 in Table 2 below, the electrophotographic toners "Toner 1" and "Toner 2" in the examples of the present invention are the same as the electrophotographic toners "Toner 3" and "Toner 4" in the comparative examples. Compared to this, after driving and stirring the developer for 15 hours, there is less variation in optical reflection density in the image forming area and less increase in scumming in the non-image forming area, and the toner has high durability and stability. In Toner 3 and Toner 4, the optical reflection density decreased due to white spots where no toner adhered to the image forming area due to uneven development due to toner aggregation. The optical reflection density of the non-image forming area increased due to scumming due to the generation of peeled matter.

[Effects of the Invention] As described above, according to the present invention, in an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material, the toner which is the main component of the electrophotographic toner Resin particles made of the first resin are dispersed on the surface of the inner core, and a resin coating layer made of the first resin and the second resin is formed in a resin particle-dispersed resin solution in which the second resin is dissolved. This makes it possible to improve the durability and stability of the toner.

In addition, in a method for manufacturing an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material, there is a step of preparing a toner inner core, which is a main component of an electrophotographic toner, and a step of preparing a toner inner core, which is a main component of the electrophotographic toner. A step of dispersing resin particles in a resin particle-dispersed resin solution in which a second resin is dissolved, and a toner inner core that is soluble in the resin particle-dispersed resin solution and consists of the first resin. A step of adding a solvent in which both the resin particles and the second resin are insoluble to form a resin particle adhesion layer on the surface of the toner inner core, which is made up of resin particles made of the first resin and a second resin, and adhesion of the resin particles. By having a step of dissolving the layer and forming a resin coating layer composed of the first resin and the second resin on the surface of the inner core of the toner, there is little variation in film thickness on the surface of the toner, and it can be applied over the entire circumference of the toner. It became possible to form a uniform resin coating layer. Furthermore, since the film thickness was determined by the particle size and adhesion amount of the resin particles, the reproducibility of the film thickness for each resin coating treatment was good.

The toner for electrophotography of the present invention can be used in an apparatus that forms an image by visualizing an electrostatic image formed on a dielectric material with toner, transferring and fixing the image onto an image-forming object, such as a printer.
It can be widely used in copying machines, facsimile machines, etc., and it is also possible to produce electrophotographic toner for use in such devices.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the electrophotographic toner of the present invention. FIG. 2 is a flowchart of the method for producing electrophotographic toner of the present invention. 1... Toner inner core 2... Binder resin 3... Colorant 4... Magnetic powder 5... Release agent 6... Resin coating layer 7... Charge control agent 8... Fluidizer 11...Resin particles 12 made of first resin...Second
Resin, solvent dispersion, mixed dispersion, precipitating solvent, interfacial precipitation, resin particle adhesion toner, dissolving solvent, dissolving film formation, resin coated toner, external additive treatment, toner for electrophotography and above

Claims (2)

[Claims] (1) In an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material, resin particles made of a first resin are dispersed on the surface of the inner core of the toner, which is the main component of the electrophotographic toner. A toner for electrophotography, characterized in that a resin coating layer is formed of a first resin and a second resin in a resin solution containing resin particles dispersed in which the second resin is dissolved. (2) In a method for manufacturing an electrophotographic toner for visualizing an electrostatic charge image formed on a dielectric material, a step of preparing a toner inner core, which is the main component of the electrophotographic toner, and a step of preparing the toner inner core are performed. A step of dispersing resin particles made of the first resin in a resin particle-dispersed resin solution in which a second resin is dissolved; A step of adding a solvent in which both the resin particles consisting of the first resin and the second resin are insoluble to form a resin particle adhesion layer consisting of the resin particles consisting of the first resin and the second resin on the surface of the toner inner core, and the resin particles A method for producing an electrophotographic toner, comprising the step of dissolving an adhesion layer and forming a resin coating layer made of a first resin and a second resin on the surface of the inner core of the toner.