JPS585752A - Magnetic toner for electrostatic transfer type electrophotography - Google Patents

Abstract

PURPOSE:To obtain an insulation characteristic magnetic toner of superior transfer characteristics, gradation characteristics, etc. by using the mixture of specific ratios of insulation characteristic resin particles contg. magnetic powder and an electrostatic charging controlling agent of insulating and non-magnetic characteristics which is electrostatically charged to the same polarity as that of electrostatic latent images by friction with said particles as a toner. CONSTITUTION:Insulation characteristic magnetic resin particles 2 contg. magnetic powder and an electrostatic charging controlling agent 1 which contg. no magnetic powder, is of a reversed polarity and is electrostatically charged to the same polarity as that of electrostatic latent images by friction with the particles 2 are used in preparing a magnetic toner wherein the controlling agent 1 is contained at 0.1-25wt% out of the total weight of the particles 2 and the agent 1. Oxides of elements of the II, III and IV groups of periodic table (including lanthanide system) or org. compds. of these elements (more particularly, aliphat. metallic salts) which have >=10mu average grain sizes are used for the agent 1. The particles having 1-30mu average grain sizes are used for the particles 2. Both particles 1, 2 are provided with >=10<11>OMEGA.cm volume resistivity. In this way, the magnetic toner which yields high quality images stably at all times irrespectively of the quality of paper and atmospheric humidity is obtained.

Description

[Detailed description of the invention] The present invention relates to an electrostatic transfer type electrophotographic magnetic toner.

An image is formed as an electrostatic latent image on a uniformly charged photosensitive drum, and this static IIc latent image is transferred to plain paper through a development process in which it is visualized using toner. Two-component toners are already well known as toners.

This two-component toner is made by mixing toner particles made of resin and carbon black or dye with carrier particles made of magnetic powder such as iron powder or glass beads, and the two components are made to have opposite polarities to each other under frictional conditions. According to the magnetic brush method, the toner is attracted to the outer circumferential surface of a non-magnetic sleeve containing a rotating magnet as a magnetic brush and transported to the development position where it contacts the photosensitive drum, bringing the toner into contact with the electrostatic latent scratches. Visualize it, that is, make it appear. Therefore, although the carrier particles play a role in charging the non-magnetic toner particles and transporting them to the development position, they are not consumed during the development process, and are subsequently collected from the sleeve and mixed with the toner particles again to be recycled. used. For this reason, in electrophotography using two-component toner, it is necessary to replace carrier particles that have deteriorated due to repeated use, and it is necessary to replace carrier particles that have deteriorated due to repeated use.
In order to form an image, it is necessary to replenish toner particles and maintain a proper violet ratio with carrier particles at all times, and there is also a tendency for devices to become larger.

In order to solve these problems with two-component toners, -component conductive toners have been proposed in recent years, and these -component toners are made by uniformly distributing conductive substances such as magnetic powder and carbon black into a resin. It is a granule dispersed in This toner is attracted by its own magnetism to the outer circumferential surface of the conductive sleeve containing a rotating magnetic pole, is transported to the development position, contacts the electrostatic latent scratches on the photosensitive drum, and is transferred from the sleeve by electrostatic induction. It is injected with an electric charge of opposite polarity to the scratch, becomes electrically charged, adheres to the latent material, and develops it. Therefore, with such a development method, the toner image generally lacks gradation, and while development utilizes the conductivity of the toner, the transfer of the toner image to the transfer paper is performed using toner particles such as corona transfer. Take advantage of the insulation properties of Therefore, with the conventional one-component toner, the toner image is not accurately transferred to the transfer paper during transfer, and the polarity changes and the toner image flies.
It is difficult to form a clear image. Furthermore, toners with contradictory properties of conductivity and insulation lack stability, and image quality varies depending on the type of paper and atmospheric humidity.

On the other hand, a -component type insulating toner has also been proposed, but this toner cannot have a sufficient charge when developed by the usual magnetic brush method, so a satisfactorily clear lIj image cannot be obtained.

The present invention has been made to solve the various problems described above, and is substantially insulative and has excellent transfer characteristics, as well as excellent drawing characteristics including gradation reproducibility. The purpose of the present invention is to provide an excellent insulating magnetic toner.

The electrostatic transfer type magnetic toner for electrophotography according to the present invention is an insulating non-magnetic resin that is charged to the same polarity as the electrostatic latent image due to friction between insulating magnetic resin particles containing magnetic powder and the insulating magnetic resin particles. A magnetic charge control agent is contained, and the proportion of the charge control agent in the total amount of the insulating magnetic resin particles and the charge control agent is 0.1 to 25% by weight.

The insulating resin particles used in the present invention contain magnetic powder and have a volume resistivity of 10119, preferably 1013.
These are magnetic resin particles having a value of ρ・1 or more.

The magnetic powder is preferably an L ferromagnetic substance, specifically metals such as manganese, iron, cobalt, nickel, and chromium, metal oxides such as chromium dioxide, iron sesquioxide, and triiron tetroxide;
Ferrite etc. are used. The content of magnetic powder in the insulating magnetic resin particles is appropriately determined depending on the magnetic force required to convey the particles on the sleeve and the type of magnetic powder. In addition, as for the resin, the resin particles containing magnetic powder must have the above-mentioned volume resistivity and have a melting point that can be finally fixed on the transfer paper by heat or pressure. Natural resins such as rosin, quelac, copal resins and their modified resins, synthetic resins such as vinyl resins, acrylic resins, styrene resins, styrene-acrylate copolymer resins, alkyd resins, phenolic resins, amino resins, epoxy resins, natural resins, etc. Rubber, synthetic rubber, or a mixture of two or more thereof may be used, and may contain a low melting point component such as an aliphatic wax or a low molecular weight synthetic resin, or a coloring agent such as a dye or pigment, if necessary.

The particle size of the winter insulating resin particles is usually 1 to 30 μm, preferably 3 to 25 μm, because too small a particle size tends to cause background stains on paper, and on the other hand, if it is too large, the resolution decreases, and in either case, the image quality deteriorates. within the range of.

The magnetic toner according to the present invention contains an insulating and nonmagnetic charge control agent that is charged to the same polarity as the electrostatic latent image by friction with the insulating resin particles. As a charge control agent, it is a special Kl! as long as it has such properties. Any one can be used without being subject to NIIa, but from the viewpoint of toner fluidity, storage stability, etc., those from Groups Ⅰ, Ⅲ, and Ⅲ (including lanthanide series) of the periodic table are preferred. Oxides of the elements and organic compounds containing the above elements are preferred. Preferred specific examples of oxides include silica, alumina, titanium oxide, calcium oxide, magnesium oxide, cerium oxide,
Examples include europium oxide, borosilicate, calcium silicate, and the like. Further, as the organic compound containing the above elements, fatty acid salts, complex compounds, etc. are preferable, and specifically, barium stearate, zinc stearate, cadmium stearate, trisdipivaloylmethanatoeuropium, etc. When the latent image is of negative polarity, for example, borosilicate, calcium silicate, cerium oxide, silica, etc. are selected, and when the latent image is of positive polarity, for example, barium stearate, cadmium stearate, etc. are selected.
Trisdipivaloylmethanatoeuropium and the like are used.

The content of the charge control agent in the magnetic toner ranges from 0.1 to 0.1 based on the total amount of the insulating magnetic resin particles and the charge control agent.
25% by weight, preferably 0.5-20% by weight. In addition, the volume resistivity of the charge control agent is l Qll Ω・
The particle diameter is usually 100^ or less, preferably 5μ or less. In the present invention, since the charge control agent is also consumed in the developing process, if the particle size is too large, the image becomes unclear, which is not preferable.

A one-component toner consisting only of general Ke-edge magnetic resin particles is positively or negatively charged due to friction between the toner particles, and as shown in FIG. 1, the toner as a whole is neutral;
At least some of the particles are positively charged and at least some are negatively charged. In the figure, N indicates the number of particles and Q Company's charging pupil.

However, depending on the polarity of the electrostatic latent image, the amount of charged toner particles that can be used for the #L image, such as negative polarity particles (indicated by the shaded area), is not sufficient, and as a result, the amount of charge on the electrostatic latent image is When tll# is large, relatively good development can be achieved, but when it is small, there are few toner particles adhering to tll#, and the gradation reproducibility is particularly poor, making it impossible to obtain high quality iii*.

As shown in FIG. 2, the charge control agent 1 in the present invention forms a toner together with insulating magnetic resin particles 2, and although the toner as a whole is neutral, it becomes static due to friction with the insulating magnetic resin particles. In addition to being charged to the same polarity as the electrostatic latent image, at the same time, the insulating magnetic resin particles are charged to an opposite polarity to the electrostatic layer 11, and as shown in FIG. As a medium, insulating resin particles charged with opposite polarities are bonded to each other to widen the charge distribution and increase the amount of charge, thus producing a latent image with high gradation reproducibility depending on the amount of charge of the electrostatic latent image. This makes it possible to develop the image accurately.

Furthermore, in the magnetic toner according to the present invention, while adsorbing the charge control agent charged to the opposite polarity by friction, the magnetic toner of the insulating resin particles transports the outer circumferential surface of the sleeve having a built-in rotating magnetic polarity to the development position. , since the charge control agent is consumed in development together with the insulating resin particles,
Unlike two-component toners, there is no need to substantially replenish insulating resin particles or charge control agents.

Therefore, in the present invention, if the relative amount of the charge control agent to the insulating resin particles is too small, the above effect will not be sufficiently expressed, while if it is too large, the charge of the charge control agent will hinder development and 1 Copy 111 (#) is not preferable because it may cause white spots in solid black areas, resulting in a low-quality image.

The insulating magnetic resin particles in the present invention are prepared by kneading the resin, magnetic powder, and other additives as necessary using a heated roll, heated kneader, extruder, etc., cooling, and pulverizing the particles according to a known method. Classify to obtain particles within a predetermined size range.

As described above, according to the magnetic toner of the present invention, the insulating magnetic resin particles and the charge control agent are rubbed together, the charge control agent is charged to the same polarity as the electrostatic latent image, and the electrostatic latent image is By increasing the amount of insulating magnetic resin particles that are charged with opposite polarity and at the same time electrostatically adhering the charged insulating magnetic resin particles to a chargeability control agent, the amount of charge on the resin particles is increased; Since the charge distribution is widened, development can be performed with excellent gradation reproducibility depending on the charge density of the latent image. ! I! Furthermore, since the charge control agent is non-magnetic, it is adsorbed to the insulating magnetic resin particles and consumed during development, so there is usually no need to replenish the charge control agent or the insulating magnetic resin particles. Furthermore, since the magnetic toner of the present invention is insulating,
In electrostatic transfer such as corona transfer, images are accurately and clearly transferred to transfer paper such as plain paper, and a high-quality image can be provided regardless of the type of paper or atmospheric humidity.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A mixture consisting of % by weight and 40% by weight of triiron tetroxide as magnetic powder was heated, mixed, and then finely pulverized with a jet pulverizer,
Insulating magnetic resin particles having an average particle size of 15 μm were obtained. 98 parts of these insulating magnetic resin particles were added as a charge control agent with an average particle size of 5.
Two parts of 00 mμ borosilicate were uniformly mixed to form a toner.

When the image was copied onto plain paper using a conventional magnetic brush method using a copying machine equipped with a selenium drum as a photoreceptor and a rotating magnetic pole, a clear copy image with good gradation was obtained. The image remained stable even after many copies were made.

Example 2 98 parts of the insulating magnetic resin particles obtained in Example 1 were uniformly mixed with 2 parts of cerium oxide having an average particle size of 100ff1μ as a charge control agent, and this was used as a toner and copying was carried out in the same manner as in Example 1. As a result, a clear copy image with good gradation was obtained. Even after making multiple copies, the image remains stable and round.

Example 3 55% by weight of epoxy resin, 40% triiron tetroxide as magnetic powder
After heating and kneading a mixture consisting of 5% by weight of nigrosine dye, the mixture was pulverized using a jet pulverizer to obtain insulating resin particles having an average particle size of 15 tones.

To 97 parts of the insulating magnetic resin particles, 3 parts of lithium stearate having an average particle diameter of 80 mμ was uniformly mixed as a charge control agent to prepare a toner.

When the image was copied onto plain paper using a conventional magnetic brush method using a copying machine equipped with a cadmium sulfide drum as a photoreceptor and a rotating magnetic pole, a clear copy image with good gradation was obtained. The image remained stable even after many copies were made.

[Brief explanation of drawings]

FIG. 1 is a model diagram showing the frictional band distribution of a toner consisting only of insulating magnetic resin particles, and FIG. 2 is a model diagram showing the triboelectric charge distribution of insulating resin particles and a charge control agent in the toner of the present invention. , FIG. 3 is a model diagram showing the toner of the present invention. 1... Chargeability control agent, 2... Insulating resin particles. Figure 2 N -〇 〇 +Q Procedural amendment (voluntary) 1. Description of the case Patent Application No. 103831 of 1983 2 Name of the invention Static transfer type pentad photographic magnetic toner 3 Relationship with the case Patent applicant Address Kobe City Ordinance Jg I) <: Akira + II Letter 31ge 2 No. 15 Name Band - Chemical Law Company 4, Agent 5, Date of amendment order: Showa, month, day (Ship date: Showa, month, day) Contents of amendment (1) Details, J! ) “Manganese,” and “
, chrome". that's all

Claims (7)

[Claims] (1) Contains insulating magnetic resin particles containing magnetic powder and an insulating non-magnetic charge control agent that is charged to the same polarity as the electrostatic latent image due to the single vibration of the insulating magnetic resin particles; A magnetic toner for static transfer type electrophotography, characterized in that the proportion of the chargeability control agent in the total weight of the magnetic resin particles and the chargeability control agent is 0.1 to 25% by weight. (2) Claim 1, characterized in that the anti-irritant cape is made of oxides of elements of Groups Ⅰ, Ⅲ and Ⅲ (which belong to the lanthanide series) of the Ordinance Table. The electrostatic transfer type magnetic toner for electrophotography as described in . (3) Claim 1, characterized in that the zonation property controlling agent is an organic compound of an element in Groups 1, 2, and 3 (referring to the lanthanide series) of the periodic table. A magnetic toner for photographic use of the silent transfer type 'Seiko' described in Section 1. (4) The electrostatic transfer electrophotographic magnetic toner according to claim 4, wherein the chargeability control agent is a fatty acid metal salt. (5) Both the insulating magnetic resin particles and the charge control agent are 10
The magnetic toner for electrostatic transfer type electrophotography according to claim 1, which has a volume resistivity of 119·α or more. (6) The electrostatic transfer type magnetic toner for electrophotography according to claim 1, wherein the insulating magnetic resin particles have an average particle size of 1 to 30 μm. (7) The magnetic toner for electrostatic transfer type electrophotography according to claim 1, wherein the chargeability control agent has an average particle size of 10 μm or less.