JPS5919952A - Developing agent - Google Patents

Abstract

PURPOSE:To obtain a developer consisting of a toner and a resin coated carrier capable of charging the toner to any polarity. CONSTITUTION:The present developer consists of the toner and the carrier coated with a resin capable of controlling the chargeability characteristics of the toner, and the toner can be controlled to a desired polarity and charged amt. by selecting said coating resin. As the toner material, a styrene-acrylic copolymer, polyester, epoxy, and the like resins are used. Said carreier can be prepared by immersing the iron powder of the core material into an org. soln. of said resin, or spraying said resin soln. over the iron powder being fluidized, or doing the like, heat-treating the core material coated with the resin soln. at a prescribed temp., and forming the coating layer on the surface of the core material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to, for example, an electrophotographic dry developer, particularly a carrier in a two-component developer consisting of a toner and a carrier. The present invention relates to a resin-coated carrier in which a spherical iron powder carrier is coated with a resin in consideration of the frictional electrification series with the toner, and the negative and positive chargeability of the same toner can be arbitrarily controlled.

[Technical background of the invention and its problems]

When setting the charging polarity of the toner in a conventional two-component developer, select a toner resin binder that matches the desired polarity during frictional charging with iron powder or resin coating material, and add a charge bacteriostatic agent as necessary. This is done by incorporating fluidity improvers, mold release agents, etc. This resin binder must satisfy fixing properties, anti-offset properties, fluidity, and impact resistance against agitation in a developing device. Typical resin binders that meet the above requirements include polystyrene, styrene-acrylic copolymer, polyester, polyvinyl phtyral, epoxy resin, and ethylene-vinyl acetate copolymer, and most of these are iron oxide powder carriers. Most of them have negative polarity due to frictional electrification with. There are curdled, positively charged resins and polyamide-based resins.

Therefore, when making a toner using the above resin, a charging antibacterial agent is added to invert the charge amount or reverse the charge polarity, and a positively charged toner contains an electron-donating dye such as nigrosine. The negative can (71 g) is mainly used, and the negative can (71 g) contains electron-accepting organic J11 bodies. In this case, the weight is determined by the compatibility and dispersibility of the binder resin.

As described above, in the past, in order to adjust the desired charging polarity, toner had to be manufactured for each polarity using the above-mentioned method, which was extremely troublesome.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to make it possible to charge both positive and negative @ polarities of the same toner without producing toner for each polarity. The purpose is to provide a developer.

[Summary of the invention]

The present invention includes a toner and a resin-coated carrier coated with a resin that inhibits the charging properties of the toner. By selecting the coating resin described above, the toner can be made to have desired polarity and charge amount.

The present invention provides a carrier that can control the charging polarity of toner and has excellent durability.More specifically, the carrier that is suitably used in the magnetic brush method The present invention provides a carrier for an electrophotographic dry developer having a core material having a covering layer of methacrylic resin or polytetrafluoroethylene on the surface thereof.

The toner used in the present invention is not particularly limited, and may include styrene-acrylic copolymer, polyester resin,
Joxy resin, ethylene-vinyl acetate copolymer, etc. can be used.

In addition, the basic carrier is a mixed solvent of organic solvents such as acetone, methyl ethyl ketone, methyl imbutyl ketone, toluene, xylene, or ethyl acetate, and polymethyl methacrylate resin. Depending on the situation, the above steps can be carried out by dipping the core iron powder into a resin solution in which other resins or additives are dissolved, or by fluidizing the iron powder and spraying the above resin solution onto it. After coating the core with the θj welding weld, it is heat-treated at a predetermined temperature to form a core light control [i[1]
ni'4. It is possible to create iM by forming a value layer. In this case, 4 bilimer O
There are no particular limitations on the A+ degree, but in the case of the -17 degree method, a degree of 2 to 15 wt is preferable, considering the solution viscosity and the efficiency of the drying process after coating. Examples of polymethyl methacrylate resins include Acrylic 4T M1SM7 IJ:l:I-INAC manufactured by Mitsubishi Rayon, Sumipec B-LG manufactured by Sumitomo Chemical, and Methyl PET 50 H manufactured by Fukkasei.
,6ON.

Delpowder and the like are preferably used.

[Practice of the invention]

Hereinafter, the present invention will be explained in more detail with reference to each example. 1
First, an example of φ:1 will be described.

A coating stock solution is prepared by dissolving 1 part of methyl methacrylate 1 fat Acryvet M (manufactured by Mitsubishi Rayon) in a mixed solvent of 25 parts by weight of toluene and 145 parts by weight of ethyl acetate.Then, this coating stock solution is diluted with methyl methacrylate. Prepare a diluted 1-1 coating solution with 140 parts of ethyl carbonate, and use a fluid coating device to coat the solution to 39 to 105 parts.
The coating liquid was spray coated on 74 parts of 3000'g of flat irregular shaped iron powder (apparent density 2.89g10n3) having an equal particle size distribution in microns. Thereafter, the coated iron powder is fluidized and heat treated at 145° C. for 1 hour to form a carrier for a dry developer for electrophotography. In addition, the toner is styrene-acrylic resin SBM 600' Tg7
0°C, CMn = 29,700, MW = 73,300
(manufactured by Sanyo Kasei), 6 parts of Carbon MA100, and 4 parts of Microcrystalline Wax 220 are melt-kneaded using three rolls, pulverized using a jet mill, and then classified to produce a toner.

After that, dry developer carrier 1000 was formed as described above! 1 ton of 40 parts by weight of toner was weighed into a polyethylene bottle, and stirred at 110 rpm for 1 hour to prepare a developer. The amount of charge of the toner in this developer was measured using a pull-off powder charge amount measuring device manufactured by Toshiba Chemical Co., Ltd., and it was found to be Q16.5 μC/g. Further, the current of the developer was 0.72 μA. When an electrostatic latent image on the Se photoreceptor was developed using this developer using a Toshiba copying machine BD-7501, a clear copy image could be obtained.

Next, a second example will be described. First, 100
A spherical iron powder carrier with a particle size distribution of ~200 mesh (apparent density 2.91 g/cm') was placed in a 400 mesh sieve and shaken over trichlorethylene vapor to adhere polytetrafluoroethylene fine particles. At the same time, shake off excess fine particles. This iron powder carrier with fine polytetrafluoroethylene particles is placed in a heating furnace into which hot air at 400° C. is blown from the bottom by a melting and dispersion cooling method to melt and solidify the carrier. After cleaning and cleaning, the applied iron powder is shaken using a fluidized air bed, 3
Heat treatment is performed at 60°C for 1 hour. The current directivity of the resin-coated carrier thus produced was 21 μA. This tetrafluoroethylene resin coated carrier was
Similar to the implementation ρl, the frictional charge amount obtained by mixing with the toner of the first example (the direct value is 17.5 μC/9, and compared with the first example described above, the same toner is charged and superimposed. The absolute polarities of the two are almost equal, and the charging polarities are completely reversed.The current polarity of this adjusted developer was 0.32 μA.This developer was When we changed it to a negative value and performed reversal development on a Se photoreceptor, we were able to obtain clear images and no fog even after 50,000 cycles, and the amount of electricity per liter was also 16.3 μC. /g and stable.

Next, a third example will be described. First, 10 parts by weight of epoxy resin 1004 (manufactured by Shell Chemical Co., Ltd.) and 8 parts by weight of polyamide curing agent Tomide 225 (manufactured by Fuji Kasei Co., Ltd.) are dissolved in 20 parts by weight of xylene and 10 parts by weight of verbutanol to prepare a coating stock solution. . The above coating solution is diluted with 150 parts by weight of methyl ethyl ketone to prepare a coating solution, and an amorphous iron powder carrier having a particle size distribution of 74 to 149 microns is spray coated using a fluidized coating device. Afterwards, while fluidizing the applied iron powder,
Heat treatment is performed at 0° C. for 1 hour to obtain a carrier for a two-component developer. The current value of this carrier was 2.4 μA.

A developer was prepared in the same manner using the carrier thus obtained and the toner of the first embodiment ρU. As a result, the charge amount of the toner was Q10.5 μC/g. When the above developer was used for current collection, a clear copy image was obtained.
Even after 0,000 times of development, the amount of charge on the toner is Q20.8μ
It was stable at c/9.

Next, a fourth example will be described. first,? 90 parts of lyamide resin SAM 955 (Sanyo Kasei M),
It is manufactured by melting and kneading 6 parts of Carbon MA100 (manufactured by Mitsubishi Kasei) and 4 parts of Microcrystalline Wax 220 (manufactured by Mopil Oil) using three rolls, pulverizing with a jet mill, and then classifying. After that, this toner was transferred to an iron powder carrier DSP-128B (manufactured by Dowa Iron Powder, apparent density 2,
90 jj/cm3.100~250 meters) and 40
: When the mixture was mixed in a 1000-weight machine and the amount of charge was measured, the amount of charge obtained was 19.3 μC/&. The charge amount of this toner was measured in the same manner as the methacrylic resin coated carrier of the first example, and the result was Q16.2μC/
It was 9. When this developer was used to produce an image using a copying machine, a clear image was obtained.

It should be noted that the current values in each of the above-mentioned embodiments were measured by the current measurement circuit shown in the drawings.

The measurement was performed at a distance of 5 mm between the photosensitive drum 1 and the sleeve (developer brush) 2, and a rotation speed of the sleeve 2 of 16 Orpm.
It was carried out under the same conditions.

In addition, in the figure, 3 is a DC power supply (100VDC) -c, 4 is a resistance (lkΩ), and 5 is mV.

〔Effect of the invention〕

What does the present invention mean? As explained above, since it consists of a toner and a resin-coated carrier containing a resin that controls the chargeability of the toner, the IJv of the toner is
Without changing the resin formulation of the resin binder or using dyes, you can create toner with the desired polarity.
The charge can be controlled (IMl). 1. Therefore,
It is not necessary to produce toner for each polarity, and the toner can be used in common, which is extremely convenient.

[Brief explanation of the drawing]

The drawing is a measurement circuit diagram for determining the current (direction) in each implementation relay. 1... Photoreceptor drum, 2... Snob, 3...
DC lightning, source, 4...resistance.

Claims (7)

[Claims] (1) A developer consisting of a toner and a resin-coated carrier coated with a resin that controls the charging characteristics of the toner. (2) The developer according to claim 1, wherein the resin-coated carrier is a positively charged toner whose triboelectricity with the iron powder carrier is negative. (3) The developer according to claim 1, wherein the resin-coated carrier is a negatively charged toner whose triboelectricity with the iron powder carrier is positive. (4) The developer according to claim 2, characterized in that a fluororesin is used as the resin coat. (5) The developer according to claim 3, characterized in that a methacrylic resin is used as the resin coating material. (6) The developer according to claim 2, characterized in that a styrene-acrylic copolymer resin is used as the toner material. (7) The developer according to claim 3, characterized in that a polyamide resin is used as the toner material.