JPH0451249A - Magnetic toner and production thereof - Google Patents

Abstract

PURPOSE:To provide the magnetic toner having sufficient magnetic permeability event at a low magnetic powder content and good flowability and preservable stability providing a layer consisting of ferromagnetic particles coated with a resin having the softening point higher than the softening point of a thermoplastic resin on internal nuclear particles consisting of the thermoplastic resin. CONSTITUTION:A mixture formed by mixing the thermoplastic resin 3 and an internal additive 2 is kneaded and is subjected to air classification after crushing and pulverizing to obtain the powder which is used as the internal nuclear particles of the toner. The ferromagnetic particles coated with the resin having the softening point higher than the softening point of the thermoplastic resin constituting the internal nuclear particles are then subjected to a mechanochemical reaction by a mechanofusion system by adjusting the substantial content thereof to >=5% and <=30% by the weight ratio and are further subjected to the air classification to obtain the magnetic toner. The constitution in which the magnetic particles 1 form films by sticking to the surfaces of the internal nuclear resin 3 is obtd. in this way. The toner forms a magnetic brush along the magnetic lines of force generated from a magnetic roll 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording material used in electrophotography, and more particularly to a toner containing magnetic powder and a method for producing the same. .

[Conventional technology]

Conventionally, as an electrophotographic method, a large number of methods have been proposed, including the Carlson process shown in US Pat. No. 2,297,691.

Generally, these methods are achieved by forming an electrostatic latent image on a latent image carrier using a photoconductive substance, and then selectively attaching colored fine powder called "toner" to the latent image. The latent image is visualized. Further, this visualized toner image is transferred to a transfer material such as paper as required, and then fixed to the transfer material by heat, pressure, solvent vapor, or a combination thereof to obtain an image-formed product.

Development methods can be roughly divided into dry development methods and wet development methods.
Dry developing methods include two-component developing methods that use toner and a toner carrier, and one-component developing methods that use only toner. Two-component development methods include a magnetic brush development method and a cascade development method, and known component development methods include a jumping development method, a FEED development method, and a magnetic brush development method.

Generally, the toner used in these development methods is a 1-diameter toner to which colorants such as dyes and pigments and charge control agents are added.
These are fine resin particles with a diameter of 0 μm, or a fluidizing agent or the like is externally attached to the surface of the fine particles.

Recently, due to the demand for downsizing and lowering the cost of equipment, and eliminating the need for maintenance and inspection, one-component development methods have attracted attention as they can simplify the development equipment and eliminate the need for developer replacement. For example, a toner has been proposed in US Pat. No. 3,639,245 that combines fine particles of ferromagnetic material such as triiron tetroxide, a thermoplastic resin such as epoxy resin, and a colorant such as carbon black. Place NBi
Sex toner was disclosed. The magnetic toner generally has poor fixing properties because it contains a large amount of magnetic powder, and to improve this, a low melting point resin is used as the resin component of the magnetic toner,
Alternatively, it is known to add a plasticizer.

[Problem to be solved by the invention]

However, conventional magnetic toners use a low softening point resin as a binder or add a plasticizer, which results in poor fluidity of the toner and the formation of agglomerates while stationary, causing electrostatic latent image bearing. This had the disadvantage of inhibiting the supply of toner to the body.

In addition, when the magnetic powder content is reduced without impairing the fixing properties, since the magnetic powder is usually dispersed in the resin without particular orientation, when the magnetic flux generated from the magnetic roll passes through the toner, It was not possible to obtain sufficient magnetic permeability because it was blocked by the resin, which is a non-magnetic material. Toner with low magnetic permeability has the drawback that the toner conveyance efficiency to the latent image area is reduced due to the small magnetic binding force in the magnetic roll, and that the toner easily falls off or scatters.

The purpose of the present invention is to solve the above-mentioned problems by creating a magnetic toner that has sufficient magnetic permeability to form a magnetic brush on a magnetic roll even at a low magnetic powder content, and has good fluidity and storage stability. Another object of the present invention is to provide a method for producing the magnetic toner.

[Means to solve the problem]

The magnetic toner of the present invention has a layer consisting of ferromagnetic particles coated with a resin having a softening point higher than that of the thermoplastic resin on core particles made of a thermoplastic resin, and the toner of the ferromagnetic particles It is characterized in that the substantial ratio to the weight is set to a predetermined weight ratio.

Further, the method for producing a magnetic toner of the present invention is characterized in that the ferromagnetic particle layer is formed by a mechanochemical reaction.

[Effect]

According to the above configuration of the present invention, since the toner surface layer is made of ferromagnetic particles coated with a resin having a higher softening point than the thermoplastic resin constituting the inner core particles, it exhibits the effect of reducing cohesion. Prevents fluidity from decreasing and agglomerates from forming. Furthermore, for the same reason, when the toner forms a magnetic brush on the magnetic roll, the magnetic flux generated from the magnetic roll passes along the ferromagnetic particle layer near the toner surface without being blocked by non-magnetic materials. , sufficient magnetic permeability can be obtained with a small content of magnetic particles.

Although there are many unknowns about the mechanochemical reaction that forms a layer of ferromagnetic particles on the surface of the inner core particle, it is a reaction that uses both thermal and mechanical energy. Through this reaction, the rain particles repeatedly collide with each other in the mixed system of inner core particles and ferromagnetic particles, and the energy given at the time of collision forms a local active region, which simultaneously arranges the ferromagnetic particles on the surface of the inner core particles. It is thought that a film is formed by fixing and repeating the fixing.

The reason why the substantial content of magnetic particles in the magnetic toner is set to 5% or more by weight is that if it is less than 5%, a magnetic binding force of the size necessary to form a magnetic brush on a magnetic roll is not obtained. This is because the amount of toner supplied to the latent image holding carrier becomes insufficient and the toner easily falls off from the magnetic roll. In addition, the reason why the amount is 30% or less is that magnetic particles exceeding 30% are difficult to immobilize, and furthermore, the effective binder ratio in the toner decreases and the adhesive strength necessary for fixing with a transfer material such as paper is reduced. This is because there is a shortage and the toner is likely to peel off from the paper.

〔Example〕

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

In the present invention, the ferromagnetic particles constituting the magnetic toner are chemically stable when dispersed in resin or wax, and preferably have a particle size of 1 μm or less, preferably 0.5 μm or less. , metal powders of iron, cobalt, nickel, chromium, and manganese, metal oxides such as chromium dioxide, iron sesquioxide, triiron tetroxide, and ferrite, and alloys that exhibit ferromagnetism through heat treatment, such as alloys containing manganese and copper. .

The binder for the inner core particles is not particularly limited, but thermoplastic resins or waxes are preferred.For example, thermoplastic resins include polystyrene and copolymers,
Hydrogenated styrene resin, styrene-isobutylene copolymer, ABS resin, ASA resin, As resin, AASA
s resin AC3 resin, ABS resin, styrene/P-chlorostyrene copolymer, styrene/propylene copolymer, styrene/butadiene crosslinked polymer, styrene/butadiene/hydrogenated paraffin copolymer, styrene/allyl/alcohol copolymer, Styrene/butadiene rubber emulsion, styrene/maleic acid ester copolymer, styrene/isobutylene copolymer (red) Styrene/maleic anhydride copolymer, acrylate resin or methacrylate resin and its copolymer, styrene/acrylic resin and copolymers thereof, such as styrene/acrylic copolymer, styrene/diethylamino/ethyl methacrylate copolymer, styrene/butadiene/acrylic acid 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 shark ester copolymer Vermilion Styrene/methyl methacrylate/acrylic 1122-ethylhexyl 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 Copolymers, polyesters and their copolymers, polyethylene and their copolymers, epoxy resins, silicone resins, polypropylene and their copolymers, fluorocarbon resins, polyamide resins, polyvinyl alcohol resins, polyurethane resins,
Polyvinyl butyral resin, etc. Furthermore, waxes include candilyra wax, carnauba wax, ceresin wax, beeswax, lanolin, montana wax, osikelite, paraffin wax, microcrystalline wax, polyethylene wax, ester wax, hydrogenated wax, etc. , a blend of two or more types can be used.

As the coating material for the ferromagnetic particles, the resin shown in the above example can be used, and the magnetic particles may be pretreated with a coupling agent or the like.The softening point of the resin is 60-140℃, 9 for coating ferromagnetic particles
It is preferable to use one having a temperature of 0 to 170°C.

In addition, additives to the inner core particles are not particularly limited, but colorants, dispersants, charge control agents, etc. that are used as internal additives in general toners can be used.For example, coloring agents can be used. As agents, pigments or dyes such as carbon black, acetylene black, graphite, black titanium oxide, triiron tetroxide, nigrosine, etc. can be used.As dispersants, metal soaps, polyethylene glycol, etc. can be used.As charge control agents, , electron-accepting metal complexes, quaternary ammonium salts, pyridinyl salts, etc. can be used.

Furthermore, fluidizing agents such as silica, titanium oxide, talc, and clay can be added as external additives.

This example will be explained in more detail below.

(Example 1) Polyester 90! A mixture of 25 parts by weight of polyethylene wax and 311 parts by weight of carbon black was kneaded with a screw extruder, coarsely pulverized with a rotobrex, finely pulverized with a jet mill, and then air classified into powder with an average particle size of 10 μm. This was used as the inner core particle of the toner. First, in order to form a ferromagnetic particle coating layer, 100 parts by weight of toner core particles and 7 parts by weight of resin-coated magnetic powder were subjected to a mechanochemical reaction using a mechanofusion system, and further air-classified, resulting in a magnetic toner with an average particle size of 11 μm. I got it.

In order to confirm the structure of the toner produced in this example, a transmission electronic! The internal #I structure was observed with an Irjlt mirror. FIG. 1 is a conceptual diagram showing this state. It has a structure in which magnetic particles 1 adhere to the surface of the inner core resin 3 to form a film. Further, FIG. 2 shows the formation of a magnetic brush on a magnetic roll using the toner in the example, in which the same elements as in FIG. 1 are given the same numbers. The toner forms a magnetic brush along the lines of magnetic force generated from the magnetic roll 4. The substantial content of ferromagnetic particles in the toner prepared in the above example corresponded to 5% of the toner weight. When the toner was put into a one-component developer equipped with a magnetic roll made of rare earth magnets and mounted on a laser printer having an organic photoreceptor to form an image, a clear image was obtained with good reproducibility. Furthermore, the fixing state was good, and no formation of aggregates or deterioration of fluidity of the toner in the developing device was observed.

(Example 2) In order to form a ferromagnetic particle coating layer on the inner core particles prepared in Example 1, toner inner core particles 100! A mechanochemical reaction was performed on 251 parts of the resin-coated magnetic powder using a mechanofusion system, and further air classification was performed to obtain a magnetic toner having an average particle size of 11 μm. The actual content of ferromagnetic particles in the toner prepared in the above example was 17% of the toner weight.
It was equivalent to When the toner was put into a one-component developer equipped with a magnetic roll made of rare earth magnets and mounted on a laser printer having an organic photoreceptor to form an image, a clear image was obtained with good reproducibility. In addition, the fixing condition is good, and the toner in the developing device is free from the formation of aggregates.
Or no decrease in liquidity was observed.

(Example 3) In order to form a ferromagnetic particle coating layer on the inner core particles prepared in Example 1, 100 parts by weight of toner inner core particles and 50 parts by weight of resin-coated magnetic powder were subjected to a mechanochemical reaction using a mechanofusion system. Further, by wind classification, a magnetic toner with an average particle size of 11 μm was obtained. The actual content of ferromagnetic particles in the toner prepared in the above example was 30% of the toner weight.
It was equivalent to When the toner was put into a one-component developer equipped with a built-in magnetic roll made of ferrite magnets and loaded into a laser printer with an organic photoreceptor to form an image,
Clear images were obtained with good reproducibility. Furthermore, the fixing state was good, and no formation of aggregates or deterioration of fluidity of the toner in the developing device was observed.

(Comparative Example 1) In order to form a ferromagnetic particle coating layer on the inner core particles prepared in Example 1, 1001 parts of toner inner core particles and 4 parts by weight of resin-coated magnetic powder were subjected to a mechanochemical reaction using a mechanofusion system. Further, by wind classification, a magnetic toner with an average particle size of 11 μm was obtained. The substantial content of ferromagnetic particles in the toner prepared in the above example corresponded to 3% of the toner weight. The toner was put into a single-component developer equipped with a magnetic roll made of rare earth magnets, but the toner did not form a magnetic brush on the magnetic roll, and when the developer was rotated, a large amount of toner was removed from the magnetic roll. Image formation was discontinued due to scattering.

(Comparative Example 2) In order to form a ferromagnetic particle coating layer on the inner core particles prepared in Example 1, 1 part of toner inner core particles 1001i and 75 parts by weight of resin-coated magnetic powder were subjected to a mechanochemical reaction using a mechanofusion system, and further After air classification, a magnetic toner with an average particle size of 12 μm was obtained. The actual content of ferromagnetic particles in the toner prepared in the above example was 36% of the toner weight.
A large number of unattached magnetic particles were present.

The toner is used in a one-component version with a built-in magnetic roll made of ferrite magnet. When the toner was placed in a laser printer equipped with an organic photoreceptor and an image was formed, the resulting image had uneven immersion and the fixation of the toner to the paper surface was not sufficient.

Although the embodiments of the present invention have been described above, the magnetic toner of the present invention and its manufacturing method are not limited to these embodiments.

〔Effect of the invention〕

As described above, since the magnetic toner of the present invention has a layer of ferromagnetic particles on the inner core particles, it is possible to obtain sufficient magnetic permeability with a small content of magnetic powder.
Since the content ratio of the magnetic material can be reduced, it has the effect of providing an inexpensive magnetic toner.

Furthermore, the present toner manufacturing method has the effect of reducing fluidity and preventing the formation of agglomerates, since the vicinity of the surface of the toner particles is composed of a layer of ferromagnetic particles coated with a resin having a high comparison point. .

The magnetic toner of the present invention can be applied to copy printers, facsimile machines, etc. using methods such as electrophotography, electrostatic recording, and magnetic recording.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a toner produced according to an embodiment of the present invention, and FIG. 2 is a diagram showing how a magnetic brush is formed on a magnetic roll using the toner according to the present invention. 1. - Ferromagnetic particles 2 - Inorganic pigment 3 - Inner core resin 4 - Magnetic roll 5 - Magnetic toner applicant Seiko Epson Co., Ltd. agent Patent attorney Kizobe Suzuki (1 person)

Claims (1)

[Claims] (1) A layer of ferromagnetic particles coated with a resin having a softening point higher than that of the thermoplastic resin is provided on the surface of the inner core particle made of at least a thermoplastic resin, and the ferromagnetic particles have a layer of ferromagnetic particles coated with a resin having a softening point higher than that of the thermoplastic resin; target ratio is 5% or more and 30
% or less. (2) A method for producing a magnetic toner, characterized in that the layer comprising the ferromagnetic particles according to claim 1 is formed by a mechanochemical reaction.