JPH02199460A - Production of toner - Google Patents

Abstract

PURPOSE:To improve the electrical conductive characteristic, fixability and preservable property of the toner by fixing fine conductive powder coated with a thermoplastic resin to the surface of base particles. CONSTITUTION:The toner is formed by fixing the fine conductive powder coated with the thermoplastic resin (e.g.; polybutyl methacrylate) on the surface of the base particles contg. a resin (e.g.: styrene/acryl copolymer) and coloring agent. The fixing of the above-mentioned fine particles to the base particles is preferably executed by the mechanochemical reaction using a high-speed fluid agitator etc., after mixing both components. The coating of the fine particles with the resin is preferably executed by a spray drying method, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dry developing toner used in electrophotography, etc. Specifically, the present invention relates to a method for producing a conductive toner.

[Prior Art] Conventionally, conductive toner used in conductive magnetic component development methods using photosensitive paper has been prepared by adding conductive powder or, most commonly, by adding special There is a method of externally adding conductive powder to the toner surface, as disclosed in Japanese Patent Publication No. 63-33696 and Japanese Patent Application Laid-Open No. 49-5035.

External addition methods include stirring the powder using a mixer, dispersing the toner, binder, and conductive powder in a solvent, and spray-drying with a spray dryer to add the binder to the toner surface. There is a method of coating the toner with conductive powder, and a method of dispersing the toner and conductive powder in an aqueous solution, adhering the conductive powder to the toner surface, and then drying it.

[Problems and objects to be solved by the invention] However, in the above-mentioned method, the adhesion of the conductive fine powder adhering to the surface is weak, and the conductive fine powder peels off from the toner surface during toner transportation and development. Charge injection is not performed sufficiently, and development characteristics deteriorate, resulting in deterioration of image quality due to a decrease in image density and background fog due to toner scattering. It also has the disadvantage that aggregation tends to occur. Furthermore, the separated conductive fine powder contaminates the inside of the device, which has the disadvantage of causing adverse effects such as mechanical failure. Therefore, an object of the present invention is to provide a toner manufacturing method that solves the above problems. That is, 1) to provide a conductive toner with excellent conductive properties and fixing properties. 2) To provide a conductive toner with excellent storage stability. 3) To provide a conductive toner with excellent fluidity. 4) To provide a stable conductive toner that does not change over time. 5) To provide a conductive toner that is easy to manufacture and inexpensive.

[Means for Solving the Problems] The toner manufacturing method of the present invention provides a toner having a conductive layer around particles made of at least a resin and a colorant.
The conductive layer is characterized in that conductive fine powder whose surface is coated with a thermoplastic resin is fixed to the surface of the toner particles.

Another feature is that conductive fine powder coated with thermoplastic resin is fixed by mechanochemical reaction to form a conductive layer.

[Operation] Since the rice mechanochemical reaction is a reaction that uses both thermal and mechanical energy, it is known that a resin layer is formed on the surface of the particles. Although there are still many unknowns regarding this point, as a result of intensive research, we have already revealed in a previously published patent that it is possible to disperse a conductive substance in the resin coating layer. Furthermore, it has now been revealed that even conductive fine powder coated with a thermoplastic resin can be firmly adhered to the surface of toner particles by mechanochemical reaction. The cause of this is that the coated conductive fine powder is affected by forces such as electrostatic force, causing particles (at least) consisting of resin and colorant (
Hereinafter, it will be referred to as a base particle. ). It is thought that by simultaneously applying thermal and mechanical energy, a portion of the resin melts and a thin film is formed. moreover,
The amount of resin for forming the conductive layer is only the amount coated on the conductive fine powder, so it is relatively small, and this allows the base particles to be made conductive without changing their viscosity characteristics. Since the base particles are completely covered, the fluidity and blocking properties of the low-viscosity base particles can be improved. In addition, since the mechanochemical reaction causes the conductive layer to firmly adhere to the base particles using its mechanical energy, it is thought that there is no deterioration in properties due to peeling or the like.

[Example] The present invention will be specifically explained by the following examples.

The base particles used in the present invention have an average particle size of approximately 10 μm and are produced by a general cross-wire crushing method, spray drying method, or polymerization method.
m can be used. Next, the carbon black is coated with a thermoplastic resin by a polymerization method, a spray drying method, or the like. The thickness of the resin layer is preferably 0.02 μm or less. Next, these base particles and resin-treated carbon black are mixed, and a conductive layer is formed on the surface of the base particles through a mechanochemical reaction. The thickness of the conductive layer is 0.1 to 0.5 in consideration of fixability and fluidity.
A range of μm is preferred.

In addition, the treatment temperature X (°C) in the mechanochemical reaction is determined by setting the lower of the glass transition point of the base particles or the glass transition point of the resin used for coating the carbon black to T ('
C), within the range of T and T-10 (T-10<X<
T). This is because if the treatment temperature is high, agglomeration of base particles or resin-coated carbon black occurs, making it impossible to form a conductive layer. Furthermore, if the processing temperature is low, no thermal change is imparted to the resin, making it impossible to form a conductive layer. As a method for carrying out the mechanochemical reaction, a so-called high-speed fluidized stirrer is used. For example, Mechano Fusion System (manufactured by Hosyo Micron), Nara Hybridization System (manufactured by Nara Kikai Seisakusho), etc. can be used. However, the apparatus for carrying out the mechanochemical reaction is by no means limited to these, and any apparatus other than the above-mentioned apparatus may be used as long as it is capable of applying mechanical and thermal energy.

The composition of the base particles is not particularly limited, and -
Boat fishing can be used. For example, thermoplastic resins include polystyrene and copolymers, such as hydrogenated styrene resin, styrene-isobutylene copolymer, ABS resin, ASA resin, As resin, AAS resin, AC8 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 maleate ester copolymer Polymers, styrene/isobutylene copolymers, styrene/maleic anhydride copolymers, acrylate resins or methacrylate resins and their copolymers, styrene/acrylic resins and their copolymers, such as styrene/acrylic copolymers Polymer, 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 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 arylate 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 copolymers, epoxy resins, silicone resins, polypropylene and its copolymers, fluorocarbon resins, polyamide resins, polyvinyl alcohol resins, polyurethane resins, polyvinyl butyral resins, etc., or a blend of two or more of them. You can use what you have.

Also, as a waxy substance, candelilla wax,
Plant-based natural waxes such as carnauba wax and rice wax, animal-based natural waxes such as beeswax and lanolin, mineral-based natural waxes such as montan wax and osikelite, natural petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum, and polyethylene wax. , synthetic hydrocarbon waxes such as Fujotscher-Tropsch wax, pernicious waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated castor oil,
Hydrogenated waxes such as hydrogenated castor oil derivatives, waxes such as synthetic waxes, higher fatty acids such as stearic acid and palmitic acid, low molecular weight polyethylene, oxidized polyethylene,
For low-temperature, low-pressure fixing, one or more of polyolefins such as polypropylene, olefin copolymers such as ethylene/acrylic acid copolymer, ethylene/acrylic acid ester copolymer, ethylene/vinyl acetate copolymer, etc. are added. Toner particles can also be used as base particles, and black dyes and pigments such as carbon black, spirit black, and nigrosine are used as colorants. In addition to this, Fe is used as a magnetic agent.
Add magnetic powder such as 5Oa, Fe2O3, Fe, Cr, Ni, Co, etc.

Further, as a dispersant, an electron-accepting organic complex, chlorinated polyester, nitrofnic acid, quaternary ammonium salt, pyridinyl salt, etc. can be added.

Next, as the thermoplastic resin for forming a coating on conductive fine particles used in the present invention, the thermoplastic resin for the base particles described above can be used in the same manner, but particularly preferably polymethyl methacrylate, polyethyl methacrylate, polyn -Butyl methacrylate, polyester, (styrene-butadiene) copolymer (PVC, PVA, PVAc
): I polymer poly γ-methyl-L-glutamate, etc. are used.

Furthermore, the conductive fine powder is not particularly limited, and fine powders such as carbon black such as furnace black, lamp black, and acetylene black, metals and metal oxides, etc. are used. Particle size is 0゜01μm~0.1μm
particles of 0.02μ are preferred, and more preferably 0.02μ
Conductive fine powder with a diameter of m to 0.05 μm is used.

Using the method and raw materials described above, a conductive layer can be formed on the surface of the coloring and fixing mother particles.

This example will be explained in more detail below.

[Example 1] [Preparation of mother particles] Styrene-acrylic copolymer 55 parts by weight Fe30
a 40 parts by weight nigrosine
Using 5 parts by weight of raw materials having the above composition, they are kneaded in a screw extruder, cooled, and coarsely ground. Next, it is finely pulverized using a jet pulverizer, and classified to a size of 5 to 20 μm (
Mother particles with an average particle diameter of 10 μm were produced.

[Formation of resin layer on conductive fine particles]

Carbon black was used as the conductive fine particles, and polybutyl methacrylate (PBMA) was used as the thermoplastic resin. These were dissolved and dispersed in acetone and spray-dried using a spray drying method to form a resin layer around the carbon black. . The composition is shown below.

Acetone: 100 parts by weight PBMA: 10 parts by weight Carbon black: 8 parts by weight The carbon black in the above solution was dispersed using an ultrasonic homogenizer, and the dispersed solution was spray-dried. A two-fluid nozzle was used for the spraying method. Spraying conditions are pressure 5kg.
/Cm2, and the drying temperature was 30°C. When the obtained powder was observed with an electron microscope, it was found to be a fine powder with a particle size of 0.05 μm and a coating resin film thickness of 0.01 μm.

[Formation of conductive layer]

The base particles prepared by the above method and the resin-coated carbon black are mixed, and a conductive layer is formed by fixing the resin-coated carbon black fine particles to the base particle surface through a mechanochemical reaction using a mechanofusion system (manufactured by Hoyoi Micron). Formed. The mixing ratio is shown below.

Base particles: 100 parts by weight Resin-coated carbon black: 8 parts by weight Furthermore, the glass transition point of the styrene-acrylic resin is 65°C, and the glass transition point of the PBMA resin is 60°C. Further, the treatment temperature was 55°C. The thickness of the conductive layer of the conductive toner thus obtained was approximately 0.1 μm. Also, the specific resistance of conductive toner is 1
It was 0.03 Ωcm. (The specific resistance was measured by the pressure cell method. In other words, the sample was placed between two electrodes, and the
The resistance was measured by applying a pressure of g/cm2.

) Next, as a guideline for fluidity, the angle of repose was measured using an electromagnetic vibration angle-of-repose measuring device. The result was 39°. Furthermore, when the conductive toner of the present invention was used to form an image on ZnO photosensitive paper by the -component magnetic brush method, it showed excellent fixing properties with an optical density (hereinafter referred to as 0.D) of 1.5. I was able to form an image. Furthermore, after conducting a durability test of 30,000 times, it was possible to form a clear image similar to the initial image without any blurring or decrease in image density.

Furthermore, when the conductive toner produced in this example was sealed in a container and stored in an environment of 30°C and 80% for 3 months, and the same test as above was conducted, there was no deterioration in characteristics and clear images were obtained. I was able to form an image.

[Comparative Example 1] The base particles prepared in Example 1 and resin-coated carbon black were mixed, and the resin-coated carbon black was attached to the surface of the base particles using a Henschel mixer. Next, image formation was performed using the toner in the same manner as in Example 1. The conductive toner produced in this example had a resistivity of 101B or more, and an angle of repose of 486, making it possible to form an image. There wasn't.

[Comparative Example 2] A conductive layer was formed on the surface of the base particles using a ball mill instead of the Henschel mixer used in Comparative Example 1, but the results were similar to those of Comparative Example 1.

[Example 2] [Preparation of base particles] Paraffin wax 40 wt% Ethylene-vinyl acetate copolymer 10 wt% Carbon black 4 wt% Fe30z
Using a raw material having the above composition of 46 wt %, it is kneaded in a screw extruder, cooled, and ground. Next, it was finely pulverized with a jet pulverizer and classified to produce a toner having a size of 5 to 20 μm (average particle size 10 μm).

[Formation of resin layer on conductive fine particles]

The conductive particles were coated with resin using a seed polymerization method. The composition is shown below.

Carbon black 20 parts by weight Styrene resin 25 parts by weight Potassium persulfate (
Polymerization initiator) 0.4 parts by weight Pure water
250 parts by weight Using these raw materials, carbon black was first dispersed in pure water using an ultrasonic homogenizer and a mechanical stirrer, and then potassium persulfate as a polymerization initiator was added and dispersed in the same manner as above. let Thereafter, half the amount of styrene resin (20 parts by weight) is added, and the temperature of the dispersion liquid is set at 45° C., and polymerization is carried out for 2 hours. Add the remaining styrene resin and raise the temperature to 75°.
The temperature was raised to C and polymerization was carried out for 4 hours. After the polymerization was completed, the solution was centrifuged to separate the solid content, which was filtered and washed with acetone, followed by drying under reduced pressure to produce resin-coated carbon black. When the obtained powder was observed with an electron microscope, the particle size was 0.05 μm, and the thickness of the resin layer was 0.
．． It was 01 μm.

[Formation of conductive layer]

A conductive toner was produced by forming a conductive layer on the surface of the base particles by mechanochemical reaction in the same manner as in Example 1. At this time, the glass transition point of the base particles was 45°C, the glass transition point of the styrene resin was 60°C, and the mechanochemical treatment temperature for forming the conductive layer was 40°C.

Next, the conductive toner produced in this example was evaluated in the same manner as in Example 1. As a result, the specific resistance is 10'Ωcm, the angle of repose is 3
It was 9°. Furthermore, when image formation was performed in the same manner as in Example 1, the same results as in Example 1 were obtained. Furthermore, using the conductive toner produced in this example, a solid image was formed on an insulating film by a -component magnetic brush development method without applying a bias voltage, and the image was thermally fixed.
We were able to create an ink sheet for thermal transfer. Therefore, the toner produced in this example can also be used as an inking material for regenerative thermal transfer.

[Example 3] Conductive toner was produced in Example 2 by changing the treatment temperature of the mechanochemical reaction. The rest was carried out in the same manner as in Example 2. The results are shown in Table 1.

Table 1 In Table 1, the conductivity result O has a specific resistance of 103ΩC.
m or less. × indicates a specific resistance other than the above.

When image formation was carried out in the same manner as in Example 1 using the conductive toners shown in Table 1, conductive toners No. 3 and No. 14 had the same results as Example 1 and could not form clear images. Ta. However, No. 1. No,
2. For No. 5, no image could be formed.

[Comparative Example 3] The conductive layer of Example 3 was formed in the same manner as Comparative Examples 1 and 2. As a result, the base particles agglomerated and could not even be obtained as a powder.

Although the embodiments of the present invention have been described above, the method of coating the conductive fine powder with resin and the formation of the conductive layer on the base particles of the present invention are not limited to these embodiments. Further, the conductive toner produced by the manufacturing method of the present invention is not limited to the image forming method of this embodiment, but can be used in any image forming method using conductive toner.

[Effects of the Invention] As described above, according to the toner manufacturing method of the present invention,
In a toner having a conductive layer around particles made of at least a resin and a colorant, the conductive layer is formed by fixing conductive fine powder whose surface is coated with a thermoplastic resin to the particle surface by a mechanochemical reaction. A conductive function can be added without changing properties that affect fixing properties such as viscosity properties. Furthermore, the small amount of resin coated on the conductive particles can completely coat the surface of the base particles, so even when using low-viscosity base particles, storage stability, fluidity, and stability are significantly improved. have an effect. Furthermore, since there is no need for operations such as classification after processing, it is possible to produce conductive toner with excellent both conductive properties and fixing properties, making it possible to provide inexpensive conductive toner. It has many effects not found in other countries.

The toner manufacturing method of the present invention can also be applied to conductive toner used in copying machines, printers, facsimiles, and the like.

that's all Applicant: Seiko Epson Corporation

Claims (2)

[Claims] (1) A toner having a conductive layer around particles made of at least a resin and a colorant, characterized in that the conductive layer is a conductive fine powder whose surface is coated with a thermoplastic resin and is fixed to the particle surface. manufacturing method. (2) A method for producing a toner, which comprises fixing the thermoplastic resin-coated conductive fine powder according to claim 1 to the toner surface by mechanochemical reaction to form a conductive layer.