JPH04333854A - Production of toner for pressure fixing - Google Patents

Abstract

PURPOSE:To provide the producing method for toner for pressure fixing not causing offsetting or aggregation, having a long service life and giving a uniform high-quality fixed image by enabling the formation of thin resin coating layers having uniform thickness. CONSTITUTION:Toner cores 9 consisting of a binding component 1 and a colorant 2 are formed and resin particles 3 having 0.05-0.5mum particle diameter and a very narrow particle size distribution with >=10,000 kurtosis are stuck to the toner cores 9 in the form of single layers. The resulting resin particle stuck toner cores 11 come into contact with a solvent 4 and resin coating layers are formed on the surfaces of the toner cores 9 to produce a toner 14 for pressure fixing by microencapsulation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing toner for use in printers, copying machines, facsimile machines, etc. that form images by electrophotography, and particularly relates to a method for producing toner for pressure fixing.

0002

[Prior Art] Conventionally, as an electrophotographic method, US Pat.
No. 297691, U.S. Patent No. 2874063, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-24748, etc., but in general, an electrostatic latent image is formed on a photoreceptor, Subsequently, the electrostatic latent image is developed with toner, the toner is transferred to printing paper, and then fixed by heating, pressure, or a solvent to obtain a printed matter.

Among the various fixing methods that have been proposed, the pressure fixing method has many advantages such as energy saving, no pollution, safety against fire, and the ability to print without any waiting time after the device is turned on. No. 3269626, Japanese Patent Publication No. 46-15876, etc. have been proposed.

Furthermore, the toner used in the pressure fixing method is
For example, Japanese Patent Publication No. 44-9880 discloses a pressure fixing toner comprising an aliphatic component and a thermoplastic resin;
Japanese Patent Publication No. 5033 describes toners made of block polymers of a tenacious polymer and a soft polymer, Japanese Patent Publications No. 1588-1988, Japanese Patent Publication No. 35867-1987, and Japanese Patent Publication No. 54-81.
Specifications such as Japanese Patent Publication No. 04 and Japanese Patent Publication No. 59-1190 describe microcapsule-type pressure fixing toners containing a soft material in the inner core.

[0005]

[Problems to be Solved by the Invention] However, the pressure fixing toners described in Japanese Patent Publication No. 44-9880 and Japanese Patent Application Laid-Open No. 48-75033, which are composed of a soft binding component, are not capable of pressure fixing. However, since the composition is soft, it tends to cause offset to the pressure fixing device, developing device, and photoreceptor, and the toners also tend to stick to each other, causing aggregation and caking.

[0006] In order to solve this problem,
Microcapsule toner in which a toner made of a soft binding component is covered with a hard resin coating layer is proposed in Japanese Patent Publication No. 1588, Japanese Patent Publication No. 51-35867, Japanese Patent Publication No. 54-8104, and Japanese Patent Publication No. 59-1190. has been done. By covering the soft toner with a hard resin coating layer, the tackiness caused by the softness of the composition is reduced, and offset to the developing device and photoreceptor, as well as aggregation and caking of toner particles, can be reduced. .

In order to obtain a uniform and good fixed image using a microcapsule type toner for pressure fixing, it is desirable that the toner cracks during pressurization be constant, and the thickness of the resin coating layer should be adjusted. It is necessary to make it uniform. In addition, in order to lower the pressure applied during fixing, it is necessary to make the resin coating layer on the toner surface thinner, but if the resin coating layer adheres to spots or has extremely thin spots, the resin coating layer may become a starting point. Offset and agglomeration begin as a result, reducing toner stability. Therefore, the resin coating layer needs to be thin and uniform in thickness.

However, conventional microcapsule production methods such as spray drying, phase separation, and interfacial polymerization described in the specification of the above-mentioned publication have difficulty controlling the amount of deposited resin coating layer, and do not produce thin and uniform microcapsules. It is difficult to obtain a resin coating layer. Therefore, in order to obtain a resin coating layer without spots or extremely thin spots, the film must be thick, and high pressure is required for fixing. Further, since the thickness of the resin coating layer is non-uniform, defects such as voids are likely to occur in the fixed image due to uneven pressure during fixing, resulting in a problem in that the image quality is degraded.

Furthermore, the combinations of materials for the toner and the coating layer are limited, the selection range of materials is narrow, and the adhesion between the toner and the resin coating layer is low, so the coating layer is likely to peel off even with the slightest impact, shortening the life of the toner. Another problem is that the length is too short.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a toner for pressure fixing, which does not cause toner offset or aggregation, has a long toner life, and provides a uniform and good fixed image.

[0011]

[Means for Solving the Problems] The method for producing a toner for pressure fixing according to the present invention includes a step of creating a toner inner core consisting of at least a binding component and a coloring material, and a particle size of 0.05 to 0 on the surface of the toner inner core. .5μm range and kurtosis 10000
A step of attaching a layer of resin particles having an extremely narrow particle size distribution as described above, and a step of contacting the resin particle-attached toner inner core obtained in the above step with a solvent to form a resin coating layer on the surface of the toner inner core to microcapsule it. It is characterized by consisting of.

0012

[Function] In the method for producing a toner for pressure fixing of the present invention, resin particles can be attached to the toner inner core by a mechanochemical method,
Since it is carried out by a spray drying method in the coexistence of resin particles, a heteroaggregation method in a solvent dispersion, etc., the adhesion can be made more uniform. The resin coating layer is formed from the resin particle layer by dissolving the resin particles with a solvent to form a resin solution layer on the surface of the toner inner core, and then drying and removing the solvent from the solution layer. Therefore, the thickness of the resin coating layer to be formed can be controlled by adjusting the particle size of the resin particles, and since the particle size distribution of the resin particles used is extremely narrow, it is possible to extremely reduce unevenness in the thickness of the resin coating layer. Can be done. As a result, thin
A toner for pressure fixing that can create a microcapsule toner for pressure fixing that has a resin layer with a uniform thickness, does not cause toner offset or aggregation, has a long toner life, and provides a uniform and good fixed image. It becomes possible to provide a manufacturing method for

The present invention will be explained in detail below with reference to Examples.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a flowchart for carrying out the method for producing a pressure fixing toner according to the present invention.

As the binding component 1, waxes and resins are used, including vegetable waxes such as candelilla wax and carnauba wax, animal waxes such as beeswax and lanolin,
Mineral waxes such as montan wax, petroleum waxes such as paraffin wax and microcrystalline wax, synthetic hydrocarbon waxes such as polyethylene wax and Fischer-Trops wax, modified waxes such as montan wax derivatives and paraffin wax derivatives,
Hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, synthetic waxes such as fatty acids, acid amides, esters, and ketones, and polyacrylate derivatives, polymethacrylate derivatives, polystyrene derivatives, butyral resins, polyester resins, cellulose resins, polyethylene resins,
Polypropylene resin, vinyl acetate resin, and thermoplastic resins such as copolymers thereof are used, and these may be used alone or in combination.

Colorant 2 includes carbon blacks, azo, azulenium, anthraquinone, indigo, thioindigo, quinacridone, polycyclic quinone, cyanine, dioxazine, squarylium, stilbene, pyrylium, Phthalocyanine-based, naphthalocyanine-based, pyridinoporphyrazine-based, perylene-based, benzidine-based dyes and pigments are used.

[0017] The resin particles 3 are made of a polyacrylate derivative,
Polymethacrylate derivatives, polystyrene derivatives, polyethylene resins, polypropylene resins, vinyl acetate resins,
and a copolymer thereof, and is produced by polymerization methods such as emulsion polymerization, suspension polymerization, and dispersion polymerization. It is also possible to use resin particles prepared by finely pulverizing or spray drying polyester resin, cellulose resin, butyral resin, etc. The particle size is preferably in the range of 0.05 to 0.5 μm, and is adjusted depending on the thickness of the resin coating layer formed on the outer periphery of the toner.

[0018] The particle size distribution is

[0019]

[Math. 1] Σ(di4・ηi)/{Σ(di2・ηi)}
4di: difference from average particle diameter ηi: kurtosis defined by frequency ratio is preferably 10,000 or more.

The solvent 4 is used to dissolve the resin particles 3 and form a resin coating layer on the surface of the inner core of the toner, and includes 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 benzyl ether, esters such as ethyl acetate and butyl acetate, ketones such as furfural, acetone, methyl ethyl ketone and cyclohexanone, benzene, toluene and xylene. and nitrogen compounds such as nitrobenzene, acetonitrile, diethylamine, aniline, dimethylformamide, and pyrrolidone, depending on the type of resin constituting the resin particles 3. The combination of resin particles 3 and solvent 4 is N. M. Bikales
, Encyclopedia of Polymer
Science and Technology
, Vol. 12, P600-625 (1970), it can be selected using the solubility parameter and the hydrogen bonding strength of the solvent as indicators.

For kneading 5, a screw extruder is used for continuous kneading, a Banbury mixer or the like is used for batch kneading, and a homogenizer, colloid mill, ball mill, etc. is used for wet kneading. The finely pulverized powder 6 is pulverized into a fine powder having a particle size of 5 to 30 μm using a jet mill, a cutter mill, an angular mill, a ball mill, or the like, and the toner inner core 7 is obtained.

When a magnetic development method is used in the electrophotographic development method, the toner inner core 7 contains ferrite, magnetite,
Magnetic powder made of magnetic materials such as iron, chromium, and nickel is added. In addition, anionic surfactants, cationic surfactants, nonionic surfactants, polyacrylate derivatives, polymethacrylate derivatives are used to disperse colorant 2 and magnetic powder in binding component 1. It is also possible to add a dispersant such as polycarboxylic acid salts such as , maleic anhydride copolymer, and Solsperse super dispersant.

Subsequently, resin particles 3 are attached to the toner inner core 7 in a process 8 to obtain a resin particle-attached toner inner core 9. For the adhesion treatment 8, a mechanochemical method using a ball mill, a shaker, an ong mill, etc., a spray drying method in coexistence with resin particles, a heteroaggregation method under solvent dispersion, etc. are used.

The toner inner core 9 to which the resin particles are attached is subjected to a coating treatment 10 with a solvent 4 to produce a toner 11 for pressure fixing.

In the case of a resin particle/solvent system having a slow dissolution rate, the coating treatment 10 is performed by dispersing the toner inner core 9 to which the resin particles are attached in a solvent, and performing filtration drying or spray drying. For systems with a fast dissolution rate, there are methods in which the toner inner core 9 with resin particles is treated with solvent vapor or solvent mist to form a film, such as spray dryer, Disper Coat (manufactured by Nisshin Engineering), Coat Mizer (manufactured by Freund Sangyo), etc. This is carried out using a coating device having a powder-liquid mixing nozzle such as .

[0026] It also stabilizes development by electrophotography,
In order to improve toner fluidity, it is also possible to add or externally add functional agents such as charge control agents and fluidity improvers. As charge control agents, organometallic complex salts such as nigrosine,
Organic salts such as alkylammonium salts, polymeric carboxylic acids, etc. are used, and as fluidity improvers, fine powders of oxides such as titanium oxide and silica, nitrides, sulfides, and fluororesins such as polyfluorovinylidene are used. is used.

The present invention will be explained in more detail by the following examples.

(Example 1) Binding component polyethylene wax
30g
Ethylene-vinyl acetate copolymer 27 g
Coloring material channel black
3g
magnetic powder magnetite
4
0 g The above was mixed and kneaded using a batch type kneader,
The powder was pulverized into fine particles of 10 to 15 μm using a jet mill to prepare a toner inner core.

Based on the total amount of toner core: Resin particles Styrene-methyl methacrylate copolymer (particle size 0.3 μm)

23
g was mixed, subjected to an adhesion treatment using an ong mill, and then subjected to a classification treatment to remove resin particles not attached to the toner inner core, thereby creating a toner inner core with resin particles attached thereto.

While discharging the toner inner core with resin particles from the powder supply nozzle, coating treatment is performed by spraying toluene as a solvent for dissolving the resin particles in a mist form from a two-fluid nozzle, thereby dissolving the resin particles and forming the coating layer. Forming was performed to create a pressure fixing toner. This is referred to as "toner 1".

(Example 2) Binding component Microcrystalline wax 50 g
butyral resin
47
G Colorant Acetylene black
3
g The above mixture was kneaded using a batch type kneader and pulverized into fine particles of 10 to 15 μm using a jet mill to prepare a toner inner core.

Based on the total amount of toner core: Resin particles Styrene-butyl methacrylate copolymer (particle size 0.4 μm)

36
g was mixed, an adhesion treatment was performed using a ball mill, and then resin particles not attached to the toner inner core were removed by a classification treatment to create a toner inner core with resin particles attached.

The inner core of the toner with resin particles attached thereto was supplied to a powder-liquid mixing nozzle, and methyl ethyl ketone was supplied as a solvent for dissolving the resin particles to perform a coating treatment, thereby producing a toner for pressure fixing. This will be referred to as "toner 2".

(Example 3) Binding component paraffin wax
48g
Ethylene-maleic anhydride copolymer 47 g
Coloring material Phthalocyanine blue
5 g of the above was kneaded using a batch type kneader and pulverized into fine particles of 10 to 15 μm using a jet mill to prepare a toner inner core.

Resin particles Methyl methacrylate-butyl methacrylate copolymer based on the total amount of toner core
(particle size 0.1μm)
10 g were mixed and subjected to adhesion treatment using mechanofusion, followed by classification treatment to remove resin particles not attached to the toner inner core to create a resin particle-attached toner inner core.

The inner core of the toner with resin particles attached thereto is dispersed in a solvent in which the dissolution rate is slowed by mixing methyl ethyl ketone, which dissolves the resin particles, and methanol, which does not dissolve the resin particles, and the resin particles are dissolved and a coating layer is formed by a spray drying method. A toner for pressure fixing was created. This will be referred to as "toner 3".

(Comparative Example 1) The entire amount of the inner core of the toner prepared according to Example 1 was dispersed in a 3% toluene solution of styrene-methyl methacrylate copolymer, and a resin coating layer was formed by spray drying, followed by pressure fixing. I created a toner for. This will be referred to as "toner 4."

For Toners 1 to 4, cross sections were observed with a transmission electron microscope to determine the average thickness of the resin coating layer. Table 1 shows the results.

[0039]

[Table 1]

In Toners 1, 2, and 3 of the present invention, a resin coating layer having a thickness depending on the particle diameter of the attached resin particles was uniformly formed over the entire circumference of the toner. However, it was observed that the thickness tended to be slightly thinner than that calculated from the particle size of the resin particles. On the other hand, in Toner 4 of Comparative Example 1, 0.02
The thickness was less than μm, and the film thickness was also non-uniform.

Next, toners 1 to 4 were subjected to a printing test using an electrophotographic printing device, and Table 2 shows the results of a comparison of development and fixing properties and cohesive properties. The development and fixing properties were judged from the presence or absence of white spots, density unevenness, etc. on the printed paper when 10,000 sheets were printed. Cohesiveness was determined by operating the printing apparatus for 10 hours without printing, and from changes in the average particle diameter and angle of repose of the toner before and after operation.

[0042]

[Table 2]

As shown in Table 2, toners 1, 2, and
In Sample No. 3, there was no printing unevenness such as white spots during development and fixation, and a good printed matter with uniform density was obtained. On the other hand, in the printed matter of Comparative Example Toner 4, white streaks and white spots were observed, and the occurrence of agglomerated toner and poor fixing occurred. Furthermore, density unevenness in solid black areas was also noticeable.

[0044] Regarding the cohesive property, toners 1, 2, and 3
In this case, there was little change in the average particle diameter and angle of repose of the toner before and after the operation of the printing device for 10 hours, and no cohesiveness was observed. On the other hand, in Toner 4 of Comparative Example, the average particle diameter is increased, the angle of repose is increased, and the toner is strongly aggregated.

[0045]

As described above, according to the present invention, in a method for producing a pressure fixing toner used in a method of fixing a toner image by applying pressure to printing paper having a toner image, at least the binding component and a step of creating a toner inner core consisting of a coloring material, and a step of creating a toner inner core consisting of a colorant and a particle size of 0.05 on the surface of the toner inner core.
A step of further adhering resin particles having an extremely narrow particle size distribution in the range of ~0.5 μm and a kurtosis of 10,000 or more, and contacting the resin particle-attached toner inner core obtained by the above step with a solvent to coat the surface of the toner inner core. By forming a resin coating layer and microcapsulating it, it is possible to form a thin and uniform resin coating layer, which eliminates toner offset and aggregation, and provides long toner life. Furthermore, it has become possible to provide a method for producing a pressure fixing toner that provides a uniform and good fixed image.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a flowchart for carrying out a method for manufacturing a pressure fixing toner according to the present invention.

[Explanation of symbols]

1. Binding component 2 Coloring material 3 Resin particles 4 Solvent 5 Kneading 6　Fine grinding 7 Toner inner core 8 Adhesion treatment 9 Toner inner core with resin particles attached 10 Film treatment 11 Pressure fixing toner

Claims (1)

[Claims] 1. A method for producing a pressure fixing toner used in a method of fixing a toner image by applying pressure to printing paper having a toner image, the step of creating a toner inner core consisting of at least a binding component and a coloring material. , a step of further adhering resin particles having an extremely narrow particle size distribution with a particle size in the range of 0.05 to 0.5 μm and a kurtosis of 10,000 or more on the surface of the inner core of the toner; and a step of adhering the resin particles obtained by the above step. 1. A method for producing a toner for pressure fixing, comprising the steps of contacting a toner inner core with a solvent, forming a resin coating layer on the surface of the toner inner core, and microcapsulating the toner core.