JPS6261072A - One-component magnetic developer - Google Patents

Abstract

PURPOSE:To obtain a high image density which is stable from an initial period without fogging and splashing and to reproduce the stable image which is not affected by age and the change of temp. and humidity by incorporating magnetic toner, pulverous negative chargeability silicic acid powder and copper oxide powder into a magnetic developer. CONSTITUTION:This one-component negative chargeability magnetic developer consists of the magnetic toner, pulverous negative chargeability silicic acid powder and copper oxide powder. The pulverous silicic powder is effective when said powder is used at 0.01-20pts.wt. per 100pts.wt. toner. Said powder exhibits the negative electrostatic chargeability having excellent stability when the powder is added to the toner more particularly preferably at 0.05-5pts.wt. The copper oxide which can be used is exemplified by copper (I) oxide Cu2O and copper (II) oxide. These metallic oxides are incorporated into the developer at 0.1-20wt%, more preferably 0.2-5wt% per 100pts.wt. toner. The grain size thereof is preferably <=5mu, more preferably in a 0.01-3mu range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer for developing latent images in electrophotography, electrostatic recording, electrostatic printing, and magnetic recording. More specifically, the present invention relates to an electrophotographic developer that is uniformly and strongly negatively charged, visualizes an iE electrostatic charge image, and produces high quality images in direct or indirect photographic development methods.

[Summary of the Disclosure] The present specification describes a negatively charged magnetic developer used in direct or indirect photographic development, in which the magnetic developer contains a magnetic toner, negatively charged silicic acid fine powder, and oxidized By containing copper powder, a stable and high image density can be obtained from the initial stage without fogging or flying dust, and technology is disclosed to reproduce stable images that are unaffected by changes in temperature and humidity over time. be.

[Conventional technology] Conventionally, electrophotography has been carried out in the following L order.

(Charging of the photoconductive layer → ■ Light image exposure (latent image formation) → ■ Adhesion of toner (development) → ■ Transfer to paper, cloth, etc. → (5) Heating,
Pressure (fixing).

There are many known developing methods for electrophotography, but they can be broadly classified into two-component developing methods and two-component developing methods. The former method is a widely used method such as a cascade method or a magnetic brush method, in which two stages of toner in which toner and carrier particles are mixed are used for development. All of these methods relatively stably produce good images, but on the other hand, they have common problems related to the two-stage developer, such as deterioration of the gear and fluctuations in the mixing ratio of toner and carrier.

In order to avoid such problems, various methods have been proposed that use a single-component developer that does not contain a carrier, but among these methods, many are superior to methods that use a developer made of magnetic toner particles.

The MagneDry method (U.S. Pat. No. 3,909,258) using conductive magnetic toner avoids the problems of the -component development method, but because the toner is conductive.

This method has a problem in that it is difficult to electrostatically transfer the developed image to a final support member such as paper.

In addition, when using a high-resistance magnetic toner, electrostatic transfer of 1
There is a developing method U that utilizes the dielectric polarization of this toner, but it has problems such as the development speed is essentially slow and a sufficient density on the developed surface cannot be obtained. Also,
Another known method using this high-resistance magnetic toner is a method in which toner particles are charged by friction with the toner particle phase or the sleeve T, but the number of times the toner particles come into contact with the friction member is small. There have been problems such as the frictional charge tends to be insufficient, and the charged toner particles tend to agglomerate in the sleeve due to the strong Coulomb force between them and the sleeve.

The applicant previously proposed a new developing method that eliminates the problems mentioned in L in Japanese Patent Laid-Open No. 55-42141. This is done by applying an extremely thin layer of insulating magnetic toner to the sleeve L, applying frictional electrification using W, and facing the electrostatic image very close to the electrostatic image using F due to the action of a magnetic field, and developing it by causing the i-toner to fly. , which is a jumping method. According to this method, the degree of contact between the sleeve and the toner is increased, - good frictional electrification is possible for a component developer, - the toner is supported by magnetic force, and the magnet and toner are moved relative to each other. % disaggregates the toner particle phase and provides sufficient friction with the sleeve! Additionally, an excellent image can be obtained by developing the toner by placing the toner facing the electrostatic image without contacting it. The amount of tripo charge is significantly smaller than the amount of tripo charge of toner particles in normal two-component development.

If a magnetic toner having only a weak charge is used in these methods, the image quality will be insufficient, such as low image density, scattering, blurring, and unevenness of the image. In particular, the initial image density is low, and usually several hundred copies are required to reach a constant density, and this instability is one of the major problems in one-component development. Further, when the developing bias is lowered in order to increase the image density, there are problems such as the occurrence of blurring.

For this reason, it was necessary to modify the amount of tripostatic charge of the magnetic toner. As a first step, it is known to add silicic acid fine powder to a negatively chargeable developer, and this improves the C degree and image quality of one image, resulting in a somewhat satisfactory image.

[Problems to be Solved by the Invention] In general, it is difficult to obtain a desired chargeability of polarity 1 in a toner [
First, a charge control agent is contained. A charge control agent is usually added to magnetite and a thermoplastic resin, heated and melted and dispersed, and then finely pulverized to adjust the particle size to an appropriate particle size before use. However, conventional negative chargeability control agents generally have complex structures, undefined properties, and poor stability. In addition, it is likely to be decomposed or altered due to decomposition during thermal kneading, mechanical impact or friction, changes in temperature and humidity conditions, and a phenomenon in which charge controllability is likely to occur.

Therefore, when a toner containing these charge control agents is used in a copying machine for development, as the number of copies increases, the charge control agent decomposes or changes in quality, which may cause deterioration of the toner during durability.

Further, many negative chargeability control agents are hydrophilic, and due to poor dispersion in these resins, the control agent is exposed on the toner surface when the toner is crushed after melt-kneading. Therefore, high humidity condition F
There is a problem in that when the toner is used in , it is difficult to obtain a good quality image because these control agents are woody.

In this way, when a conventional negative charge control agent is used in a toner, it can be applied to the toner particle surface between toner particles, between a toner and a carrier, or between a toner and a toner carrier such as a sleeve. This causes variations in the amount of R load, which tends to cause problems such as development fog, toner scattering, and carrier contamination.

When the toner is stored for a long period of time, it often deteriorates and becomes unusable due to the instability of the negative charge control agent used. There are many problems caused by these charge control agents, and although improvements in charge control agents have been studied, the current situation is that these problems have not yet been satisfactorily solved.

Furthermore, as mentioned above, by adding fine silicic acid powder to the toner, a somewhat satisfactory image can be obtained;
It was not possible to achieve a stable and even load centrality.

The present invention has been made in view of the problems of the prior art, and is capable of stably obtaining fog-free, clear, high-density images with no C degree fluctuations, especially at the initial 4 nils. The purpose is to provide a magnetic developer.

[−r=t+ and action for solving the problem] According to the present invention, a one-component negatively charged magnetic developer comprising a magnetic toner, negatively charged silicic acid fine powder, and copper oxide powder is provided. .

In this IJI Hokochu, two types of names are used for convenience, ``magnetic developer'' and ``toner.'' However, ``toner'' is the - part of ``magnetic developer,'' and binder resin, magnetic materials, dyes,
It consists of components selected from pigments, charge control agents, fluidity modifiers, lubricants, etc., and it also contains negatively charged silicic acid fine powder, copper oxide, and carbon and other additives as necessary. The added material is called a "magnetic developer."

In this specification, silicon fine powder refers to anhydrous silicon dioxide (silica), aluminum silicate, sodium silicate, potassium silicate, magnesium silicate,
Refers to silicates such as zinc silicate.

Here, the negatively charged silicon # fine powder refers to one whose charge amount with the iron powder carrier is 110 μC/g or more.

In this charge measurement, first, the test substance (silicic acid fine powder) is
0.5 to 1.5 of a mixture of iron powder carrier having a particle size of 0.07300 mesh in a ratio of 1:100.
g Weigh the viscosity. This is suctioned with a pressure of 25cmH2O using a metal 400 mesh screen L connected to an electrometer, and at that time, the amount of charge is medium compared to the sample substance that was separated and suctioned! The amount of charge per If amount is determined.

The silicic acid fine powder used in the present invention is produced by a dry method or a wet method. The dry method is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound. For example, silicon tetrachloride is expressed by the following reaction formula.

5iCh + 2H2+ 07→ 5i02 +
4 H(J') This work also includes a composite fine powder of silica and other metal oxides obtained by 'If' using another metal halide compound such as aluminum chloride or titanium chloride together with a silicon halide compound.Dry method Commercially available silicic acid fine powder (silica) produced by this method includes the following.

AEROSIL 130 (11 pieces Aerosil) 200 x50 TGOO 0X80 0X170 0K84 Cab-0-SiL M-5CA
BOT Go, (Capot Inc.) MS-
7S-5 E) I-5 Wacker HDK N 20
V15 ACKER-C: HENIE GMBHN2
0E (Wackel Hemie GNBH) T30D-CF
ine 5ilica (Fine Silica) Dow Corning Fransol (Fransol) Fran
sil (7 Langille) In addition, there are various conventionally known wet methods. For example, decomposition of sodium silicate with acid, ammonia salts or alkali salts, a method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid;
There is a method of converting an I/lium silicate solution into silicic acid using an ion exchange resin.

The following are lithograph products made of silicic acid fine powder synthesized by the wet method.

Carplex Shionogi & Co. Nip Seal Nippon Silica Toku Seal, Fine Seal Tokuyama Gotatsu Vita Seal Taki Hijiruton, Silnex Mizusawa Kagaku Star Sil
Shinshin Kagaku Himezil Ehime Yakuhin Thyroid Tomishichi Davison Kagaku Hi
-Sil (High Seal) Pittsburgh Plate Glass
Co.

(Bitzpurg Plate Glass) Durosil Ultrasil Fiillst
off-f? esellschaft Marquar
tNanosil (7 Nosil) Hardman and Ho1den (Hardman
and Holden) Hoesch (He-/Shu) Che+5ische Fabrik Hoesch
K-G (Hiemish Fagrik Herash) Si
l-Stone (Silus [--7) Stoner
Rubber Co.

(Stoner rubber) Nalco (Nalco) Nalco Chera, Go.

(Narco Chemical) Quso (shoes) Philadelphia Quartz Co.

(Philadelphia Quartz) Santocell (Santocell) Monsant
o Chemical Go.

(Monsanto Chemical) Imsil 111inois Minerals Co.

(Illinois Mineral) Calcium 5ilikat (Calcium Silicate) Chemische I'abrik Ho
esch, K-G Galsil Fiillstoff-Gesellschaft M
arquartFortafil (7 alter fill)
Imperial Chemical Industry
ies Ltd.

Microcal Manosil Hardman and Ho1den Vulkasil Farbenfabriken Bayer, A
,-G.

(Falpenfabriken Bayer) Tufkni
(7pm) Durham Chemicals Ltd.

(Do9ruham Chemicals) Silmos Shiraishi Rigyo Starex Kamishima Kagaku Fricocil
Among Taki Feriki Kei # fine powder, the specific surface area due to nitrogen adsorption measured by BET method is 30I12/g or more (especially 5
0~40h? /g) yields good results.

Application of silicic acid fine powder is 0 for 100 parts of toner
．． It is effective when added in an amount of 0.01 to 20 parts by weight, and particularly preferably exhibits negative chargeability with excellent stability when added in an amount of 0.05 to 5 parts by weight.

Copper oxide that can be used in the present invention includes copper oxide (I)
Examples include Cu2O and copper(II) oxide. Copper(I) oxide
Add an aqueous solution of hydrazine hydrate to a concentrated solution of copper(II) acetate, leave to stand, and wash the resulting yellow precipitate with water, ethanol, and then ether. Also, if glucose is added to Fehling's solution and heated, a red precipitate is obtained. Widely used as a light yellow crystalline fine powder for industrial use and as a reagent.
It has been published. Copper oxide (rI) is generally obtained as a black powder by thermally decomposing copper (II) hydroxide, steel (II) nitrate, or copper (II) carbonate at around 700°C, and it is also used industrially. It has been widely reprinted as a commercial or reagent, and for the purpose of the present invention, a purity of 90% or more will give sufficiently satisfactory results.

These metal oxides are 0.0.
It is desirable to contain 1 to 20% by weight, preferably 0.2 to 5% by weight. As for its particle size.

It is desirable that it is 5 JL or more F, preferably in the range of 0.01 to 3 JL.

The copper oxide powder applied to the present invention exhibits weak positive chargeability when measured by the two-component mesh method. Of course, magnetic toner exhibits high negative chargeability in this charge amount measurement.

When such weakly positively charged copper oxide is added and mixed with magnetic toner and placed on a developing sleeve, the frictional charging of the magnetic toner is caused by I, in addition to the conventional developing sleeve and toner phase q.
-Friction with copper dioxide appears to act as an important factor Y-. That is, the copper oxide has the ability to act as a frictional carrier for the magnetic toner, and there is an opportunity for frictional contact between the magnetic toner and the copper oxide to maintain sufficient electrophoresis in the developing sleeve 1-. Secured between. Therefore, the magnetic toner can have a high negative chargeability, and since development and transfer are performed in this state, it is thought that the above-mentioned problems in image quality due to the chargeability do not occur.

At this time, what should be considered in particular is that any combination of a weakly positively charged substance on one side and a negatively charged magnetic toner on the other will not cause image quality problems. This is because whether or not the developer can have a high negative charge amount depends on the frictional charge with the added substance, and the +'f charge amount measurement is based on the two-component mesh method (+'f charge amount is -. This is because it is a visual aid.

-In fact, in the process of completing the present invention, the present inventors discovered a substance that had a weak positive charge but had no effect using the two-component mesh method.

However, when the copper oxide used in the present invention was used in combination with fine silicic acid powder, images of good quality were obtained.

All known binder resins can be used in the present invention, including medium-sized combinations of styrene and substituted products thereof such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; coalescence, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer,
Styrene-methyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, Styrenic copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic copolymer, and mold polymer for styrene 7-maleate ester; polymethyl Methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyamide, polyacrylic resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or fatty resin Cyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffins, waxes, etc. can be used alone or in combination.

When this binder resin contains a magnetic substance and is formed into particles, the particle size is preferably 5 to 30 microns, which is the general toner particle size.

Further, as the magnetic substance contained in the binder resin, ferromagnetic elements such as iron, cobalt, and nickel, and alloys and compounds containing these, such as magnetite, hematite, and ferrite, can be used as appropriate.

Its particle size is 100 to 800 mg, preferably 3
00 to 500 parts by weight, and preferably contains 30 to 120 parts by weight, more preferably 40 to 100 parts by weight, per 100 parts by weight of the binder resin.

In addition, this magnetic toner contains a charge control agent, a flow modifier,
Colorants, lubricants, etc. may be added (externally added) or included (
In manufacturing the magnetic toner of the present invention, the constituent materials are thoroughly kneaded using a heat kneader such as a hot roll, kneader, or extruder, and then mechanically pulverized. A method obtained by classification can be applied.

Further, in order to add and contain each of the above-mentioned inorganic powders into the magnetic toner, a known mixer can be used, such as a rotary container type mixer such as a V-type mixer, a tarpaulin mixer, a ribbon type, screw type, rotary blade type, or other fixed container. A mold mixer can be used as appropriate.

Alternatively, a material such as magnetic powder is dispersed in a binder resin solution and then spray-dried.Alternatively, a predetermined material is mixed into a base material to form the binder resin, and then the emulsified suspension is obtained. Various methods can be applied, such as a modification method and a toner production method in which a magnetic toner is obtained by polymerizing the magnetic toner.

[Example] The present invention will be explained in more detail with reference to Examples below.

100 parts by weight 2 parts by weight low molecular weight polyethylene wax 4 parts by weight The above materials were mixed and melted and JQ-kneaded using a roll mill. After cooling, it is coarsely pulverized using a hammer mill, and then finely pulverized using a jet pulverizer. Next, the particles were classified using an air classifier to obtain a magnetic toner having a particle size of about 5 to 3 ol.

"-2" Various negatively charged silicic acid fine powders, copper oxide, and others were added to magnetic toner to prepare an m-type developer.

Example 1 Silicic acid fine powder synthesized by a dry method (trade name Aerosil R972, Specific Surface J!) was added to 100 parts of the magnetic toner.
3 Yose 120m2/g; 7 x Manufactured by Ogil Co.)
0.4 'Ii;i! and 2 parts by weight of copper oxide (1) (Gun 0, reagent grade 1 manufactured by Tokyo Kasei Co., Ltd.) were mixed externally to prepare a magnetic developer.

Example 2 Silicic acid fine powder synthesized by dry method (Taranox 500
A magnetic developer was obtained in substantially the same manner as in Example 1, except that 1 part by weight of Talco Co., Ltd. 5iJ) was used.

Example 3 Silicic acid fine powder synthesized by dry method (Aerosil RY20
0, specific surface area 200 m2/g; manufactured by Aerosil) 0
．． A magnetic developer was obtained in substantially the same manner as in Example 1 except that 5 parts by weight was used.

Example 4 Magnetic development was carried out in almost the same manner as in Example 1, except that 2 parts by weight of Psil E (specific surface area: 90 m2/g; manufactured by IT Hon Silica) was used in the silicic acid fine powder synthesized by a wet method. obtained the drug.

Comparative Example 1 Only 0.4i+J) part of fine silicic acid powder (Aerosil R972, specific surface area 12h'/g; manufactured by Aerosil Co., Ltd.) synthesized by a dry method was externally added to 100 tons ψ part of the same magnetic toner as in Example. The mixture was mixed to obtain a magnetic developer.

Comparative Example 2 Copper oxide CI was added to 100 parts of the same magnetic toner as in Example.
) (C: u20, Tokyo Kasei reagent grade 1) 0.4
Only the exposed portion was externally added and mixed to obtain a magnetic developer.

A negative electrostatic image is formed on a selenium photoreceptor by a conventionally known electrophotographic method, and this is powder developed using the above-mentioned various developers using a magnetic brush method to create a toner image, which is transferred to a tLf paper. Heat and fix. This method uses normal temperature and humidity (25°
C160%RH), high temperature and high humidity (35℃, 85%RH)
The image evaluation results under various environmental conditions (15℃, 10% R1 ()) are shown in Table 1 (normal temperature and humidity) and
It is shown in the table (high temperature and high humidity, low temperature and low humidity). In the table, 0 is good, Δ
indicates somewhat poor quality, and x indicates poor quality.

In each of the examples, the transferred images obtained were sufficiently flexible from the first sheet, there was no fogging, and there was no developer scattering around the image, resulting in a good image with high resolution. In addition, we created transfer images continuously and examined the durability, but 3
The transferred image after 0,000 sheets was also comparable to the initial image. At this time, no so-called filming development, in which developer adheres to the surface of the photoreceptor and adversely affects latent image formation, was observed, and no problems were found during cleaning.

In addition, even when the environmental conditions are high temperature and high humidity (35°C, 85% RH) and low temperature and low humidity (15°C, 1O%R) I), clear images almost the same as those at normal temperature and humidity can be obtained, which is satisfactory. We obtained excellent results.

In Comparative Example 1, there was little fog at room temperature and humidity, but the image density was low at 0.47, line drawings were scattered, and the solid black was extremely rough.As for durability, the density was 0.33 after 30,000 sheets. It was low. In addition, from around 10,000 sheets onwards, toner material formed a film in the form of streaks on the surface of the photoreceptor and began to appear in the form of lines on the image (filming). Even under the conditions of high temperature, high humidity, and low temperature and low humidity, the image density was low, and fogging, scattering, and roughness were noticeable.

In Comparative Example 2, the image density was relatively high compared to Comparative Example 1, but the vertical J-color was unstable and it took about 100 sheets to reach a constant density. Further, the density tended to be slightly low under high temperature and high humidity conditions and when 30,000 sheets were printed in a durability test. Also, filming started to occur after around 10,000 copies.

[Effects of the Invention] As explained above, the magnetic developer of the present invention has stable and uniform negative chargeability, and enables development and transfer faithful to the latent image. That is, there is no toner adhesion in the background area during development, that is, there is no fogging or toner scattering around the edges of the latent image, high image density is obtained, and halftone reproducibility is also good. Furthermore, there is no loss of image density, and the image density is high from the beginning.

Further, the magnetic developer of the present invention maintains its initial characteristics even after long-term continuous or repeated use and long-term storage, does not cause a filming phenomenon, and has good cleaning properties. In addition, it is a magnetic developer that reproduces stable images that are unaffected by changes in temperature and humidity, and does not cause scattering or transfer failure even in high or low humidity.

Claims (1)

[Scope of Claims] 1) A one-component negatively charged magnetic developer for electrophotography, characterized in that it contains at least a magnetic toner, negatively charged silicic acid fine powder, and copper oxide powder. 2) The mixing ratio of the negatively charged silicic acid fine powder is 1 for the magnetic toner.
The developer according to claim 1, wherein the amount is 0.01 to 20 parts by weight based on 0.00 parts by weight. 3) The developer according to claim 1, wherein the mixing ratio of the oxide is 0.1 to 20 parts by weight per 100 parts by weight of the magnetic toner. 4) The developer according to claim 1, wherein the oxide has an average particle size of 0.01 to 5 μm. 5) The developer according to claim 1, wherein the magnetic toner has an average particle size of 5 to 30 μm.