JPS6261071A - 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 manganese 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 manganese 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 manganese oxide which can be used is exemplified by manganese (II) oxide MnO, trimanganese tetraoxide Mn3O3, manganese (III) oxide Mn2O3 and manganese (IV) oxide MnO2. 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 [Industrial Application Field] The present invention relates to a developer for developing latent images in electrophotography, electrostatic recording, electrostatic printing, magnetic recording, and the like. More specifically, the present invention relates to an electrophotographic developer that is uniformly and strongly negatively charged, visualizes a positive electrostatic charge image, and produces high-quality images in direct or indirect electrophotographic development methods.

[Summary of the Disclosure] The present specification relates to a negatively charged magnetic developer used for direct or indirect f-page development, in which a magnetic toner and negatively charged silicic acid fine powder are added to the magnetic developer. By containing manganese oxide powder, a stable high image C degree can be obtained from the initial stage without fogging or flying dust, and
The present invention discloses a technique for reproducing stable images that are not affected by changes in humidity.

[Prior Art] Conventionally, electrophotography has been carried out in the following L order. ■ Leading conductive layer: i''11 electrons → Photoimage exposure (latent image formation)
→ (■ Adhesion of toner (development) → ■ Transfer to paper, IIj, etc. → (5) Heating, pressure (fixing).

There are many known developing methods for electrophotography, but they can be roughly divided into the -component development method and the -component development method. The name of the song refers to a method that has been widely used, such as the cascade method or magnetic brush method, which uses toner and carrier particles.
A two-component toner mixed with is used for development. All of these methods are methods for relatively stably obtaining good images, but on the other hand, they have common problems associated with two-component developers, such as deterioration of the carrier and fluctuations in the mixing ratio of toner and carrier. In order to avoid this problem, various methods have been proposed that use component developers that do not contain carriers, but among these methods, many are superior to methods that use developers made of magnetic toner particles.

The MagneDry method (U.S. Pat. No. 3,909,258), which uses conductive magnetic toner, avoids the problems of two-component development, but because the toner is conductive, the developed image is Electrostatically transferring to the final support member・1
9 is difficult.

In addition, when using 7q5 resistive magnetic toner, electrostatic transfer is possible, and there is a development method that utilizes the dielectric polarization of this toner, but the development speed is slow due to the woody nature of the toner, and the density on the developed surface is not sufficient. There are problems such as not being able to obtain the desired results. Another known method using this high-resistance magnetic toner is to charge the toner particles by friction with each other or with a sleeve cap, but this method reduces the number of times the toner particles come into contact with the friction member. Frictional charging tends to be insufficient (
The toner particles subjected to the i″f electric current have a problem in that the Coulomb force between them and the sleeve becomes strong and they tend to aggregate on 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 a jumping method in which an extremely thin layer of insulating magnetic toner is applied to the sleeve, it is charged by friction, and the toner is developed by being placed very close to the electromagnetic image and facing it under the action of a magnetic field, causing the toner to fly. . According to this method, the degree of contact between the sleeve and the toner is increased, and the friction zone 1E, which is good for a component developer, is made possible.The toner is supported by magnetic force, and the magnet and the toner are moved relative to each other.・By 1 yen, the toner particles are deagglomerated and are sufficiently rubbed against the sleeve.
Excellent images can be obtained by preventing ground blur due to the 'lj' bar which is developed facing the 'lj' image without coming into contact with it. However, even with this method,
The tripo charge 11V of the toner particles -f is much smaller than the amount of tripo charge of the toner particles in normal two-component development.

Is it weak in these methods? If a magnetic toner that only holds electrolyte is used, the image quality will be insufficient, such as low image quality, scattering, blurring, and image unevenness. In particular, the initial image density is low, and several hundred copies are usually required to reach a constant density, and this instability of ☆:1- is one of the major drawbacks of component-based 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 divide the amount of tripo-electrification of the magnetic toner into four parts. As this L stage, negative 1? It is known that fine silicic acid powder is added to an electrically conductive developer, and images with satisfactory image density and quality can be obtained to some extent.

[Problems to be Solved by the Invention] Generally, a toner contains a charge control agent to obtain a chargeability of 91 polarity and strength. Charge control agents are usually
Magnetite and fJ! It is added to waste resin, heated, melted and dispersed, pulverized, and adjusted to an appropriate particle size as needed before use. However, conventional negative charge control agents generally have complex structures and inconsistent properties.
Poor stability. In addition, decomposition during thermal kneading, mechanical impact,
It is easy to decompose or change in quality due to friction, changes in temperature and humidity conditions, etc., and tends to cause a phenomenon in which charge controllability is reduced.

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 may decompose or change in quality, causing 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, when the toner is used under high humidity conditions, there is a problem in that good quality images cannot be obtained because these control agents are hydrophilic.

In this way, when a conventional negative charge control agent is used in a toner, it can be used between toner particles, between a toner and a carrier, or between a toner and a toner carrier such as a sleeve.
The amount of charge generated on the surface of toner particles varies, and problems such as development fog, toner scattering, and carrier contamination are likely to occur.

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 attempts have been made to improve the charge control agents, 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, but if this is done alone, the - part of the fine silicic acid powder will aggregate and the IE will not necessarily be uniform. However, it was not possible to obtain stable and uniform load conductivity.

The present invention has been made in view of the problems of the prior art as listed in L. The present invention has a negative charging property that allows stable images with no fog, clear and high density, and no density fluctuations especially during initial printing. The purpose is to provide a magnetic developer.

[First Step and Effects for Solving the Problems] According to the present invention, a one-component negatively charged magnetic developer comprising a magnetic toner, negatively charged silicic acid fine powder, and manganese oxide powder is provided.

In this specification, "magnetic developer" and "toner" are used for convenience.
``Toner is a part of ``magnetic developer,'' and includes binder resin, magnetic material, dye, pigment,
Load '4' consists of components selected from a control agent, a fluidity modifier, and a lubricant. In addition, negatively charged silicic acid fine powder, manganese oxide, and carbon and other additives are added as necessary. What is added as appropriate is called a "magnetic developer."

In addition, in this specification, silicic acid 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 silicic acid fine powder is 4i? with the iron powder carrier? Refers to those with a charge of -10g C7g or more.

For this charge HI determination, 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.
gWeigh accurately. This is sucked into a metal 400 mesh screen connected to an electrometer under a pressure of 25 cm H2O, and then the sample substance and its electric charge are separated and sucked to determine the difference between the median weight and the amount of charge. Find the iF charge.

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 compound. For example, silicon tetrachloride is expressed by the following reaction formula.

5iCJ4 + 2H2+ Q2+ 5i
07 + 4 HCI! It also includes a composite fine powder of silica and other metal oxides obtained by Higashi, which uses this L mixture and other metal/\rogen compounds such as aluminum chloride or titanium chloride together with silicon/\rogen compounds. The 111 products of silicic acid fine powder (silica) produced by the dry process include the following:

AEROSIL 130 (11 pieces Aerosil) 200 x50 Te0O 0X80 0X170 0K84 Cab-0-SiL (-t--? Buozil) 5
CABOT Co, MS
-7S-5 E)l-5 Wacker HDK N 20
V15 buttocks ACKER-C) IEMIE GMB) l
N20E (Wackel Hemie GMBH
) T30D-CFine 5ilica (7
-r-in Silica) Tau Corning Co., Ltd. Fransol (7) Fransil (7 Ransil Co., Ltd.) Further, as the wet method, there are various conventionally known 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 are methods such as converting sodium silicate solution into silicic acid using ion exchange resin.

Commercially available silicic acid fine powders synthesized by a wet method include the following.

Carplex Shionogi & Co. Nip Seal Nippon Silica Toxeal, Fine Seal Tokuyama Sakutatsu Vita Seal Taki Hijiruton, Silnex Mizusawa Kagaku Starsil
Divine Chemical Himezil Ehime Pharmaceutical Thyroid Tomi” Davison Chemical H
i-Si! (High Seal) Pittsburgh Plate Glass Ca
.

(Pittsburgh Plate Glass) Durosil Ultrasil Fiillst
off-Gesellschaft Marquardt
(Fürsttubgesershaft Markbold) Manosil (Manosil) Hardman and Ho1den (Hardman
and Holden) HoeSch Chemische Fabrik Hoesch K
-G (Hiemish Noahfreak Herash) Sil
-Stone Stoner R
Uber Co.

(Stoner rubber) Nalco (Nalco) Nalca Cheta, Go.

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

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

(Monsanto Chemical) rmsil (imsil) 111inais Minerals Go.

(Illinois Mineral) Calcium 5ilikat (Calcium Silicate) Chemische Fabrik Hoe
scb, K-G Calsil Fiillstaff-Gesellschaft M
arquart Fortafil (7#) Iy Tough 4 Ru) I
imperial Ghe+5ical Industry
ies Ltd.

(Imperial Chemical Industries) Microcal Joseph Crosfield & 5on
s Ltd.

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

(Falpenfabriken Bayer) Tufkni
t (evening 7-t) []urham Chemicals Ltd.

(Do 9 Luham Chemicals) Silmos Shiraishi Kogyo Starex Shinshin Kagaku Fricosil
Among the two-legged silicic acid fine powders of "Tagi Fertilizer", those with a specific surface area due to nitrogen adsorption measured by the BET method in the range of 3 h2/g or more (particularly 50 to 400 m'/g) have yielded good results. I can do it.

Application of silicic acid fine powder h'! , is effective when 100 parts by weight of toner is 0.01 to 20 parts by weight, and particularly preferably exhibits excellent stability when added in 0.05 to 5 parts by weight. It exhibits negative i1?electrification.

Manganese oxides that can be used in the present invention include manganese (II) oxide MnO1 trimanganese tetroxide M11304,
Manganese oxide (m) Mn2O3, manganese oxide (I
T) MJIO? Examples include. Manganese oxide (II)
) MnO is a green powder obtained by heating manganese(II) oxalate or manganese(II) hydroxide in the absence of air, or by heating manganese(I) oxide in a stream of steam. Dimanganese tetroxide is obtained by heating manganese and submanganese oxide to 1000°C in air. It is an iron-black crystal. Manganese (III) oxide has two transformations, α and γ. α is a black crystalline crystal obtained by heating manganese oxide (FF) in oxygen at 550°C, and γ is a crystal obtained by heating manganese oxide (FF) at 550°C in oxygen, and γ is obtained by heating manganese oxide (FF) in an aqueous solution of manganese sulfate (IT). It is a tetragonal black powder obtained by adding hydrogen oxide water, further adding ammonia, washing the resulting precipitate, and heating to 250° C. in vacuum. Manganese (IV) oxide is a black powder obtained by heating manganese (II) nitrate at 150-180°C for a long time.

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.

5 or less, preferably 0. It is desirable that it be in the range of 1 to 3 O.

The manganese oxide powder applied to the present invention has a weak positive charge of 41'1' when measured by the two-component mesh U:
Indicates toughness. Of course, magnetic toner exhibits a high negative charge in this charge measurement.

When this kind of manganese oxide with a weak < FE charge is added and mixed with magnetic toner and placed on a developing sleeve, the frictional charging of the magnetic toner is different from that of the conventional developing sleeve and toner phase.
In addition, friction with L manganese oxide is thought to act as an important factor.

That is, the manganese oxide has an a function as a frictional carrier for the /ia toner, and there is an opportunity for frictional contact between the magnetic toner and the manganese oxide to maintain a sufficient amount of charge in the developing sleeve. Secured. 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 hand and a magnetic toner that has a negative 6'I charge on the other hand will not cause problems with image quality. That's not to say. This is because whether the developer can have a high amount of negative charge depends on the friction with the added substance. This is because the charge ri measurement using the two-component mesh method is a rough guide.

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

As the binder resin used in the present invention, all known binder resins can be used, but for example, polystyrene, poly-p-
Medium-sized polymers of styrene and its substituted products such as chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer 1 styrene - Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate Otama copolymer, nutyrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Polymer, styrene-butyl methacrylate large polymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer, styrene- Vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-
Styrenic copolymers such as maleic acid copolymers and styrene-maleic acid ester copolymers; 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 alicyclic hydrocarbon resin, aromatic petroleum Resin, chlorinated paraffin, paraffin, wax, etc. can be used alone or in combination.

The particle size when this E-binding resin is made into particles by containing a magnetic substance is preferably 5 to 30 L, which is the particle size of a general toner.

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 30
It is 0 to 500 m tiles, 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 (
(internal attachment) does not impede the present invention in any way.

In producing the magnetic toner of the present invention, a method can be applied in which the constituent materials are thoroughly kneaded using a heat kneader such as a hot roll, a niegu, or an extruder, followed by mechanical crushing and classification.

Further, in order to add and contain each of the above-mentioned inorganic powders into the magnetic toner, a known mixer 1 such as a rotary container type mixer such as a V-type mixer, a tarpaulin mixer, a ribbon type, a screw type single-rotation blade type, and other fixed containers is used. 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 with the intermediate to form the binder resin, and then the emulsified suspension is obtained. Various methods can be applied, such as a polymerization method and a toner manufacturing 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.

Monoiso-based chromium complex (SUVIRON BLACK TRH manufactured by Hoshichitani Chemical Co., Ltd.) 2 parts Low molecular weight polyethylene wax 4 parts The above materials were mixed and melted and kneaded in a roll mill. After cooling,
After coarsely pulverizing with a hammer mill.

Finely pulverize using a jet pulverizer. Then, it was classified using an air classifier to obtain a magnetic toner having a particle size of approximately 5 to 30 l.

A magnetic developer was prepared by adding various negatively charged silicic acid fine powders, manganese oxide, and others to the L magnetic toner.

Example 1 The magnetic toner 100. Silicon 1%2 fine powder synthesized by dry method in i'1M part (trade name Aerosil R972, specific surface area approximately 120 m2/g; manufactured by Aerosil Co., Ltd.) 0.
4! If Manganese (In) (Mn20
3. A magnetic developer was prepared by externally adding and mixing the 2nd grade reagent (grade 1) manufactured by Tokyo Kasei Co., Ltd.

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 of the magnetic developer was used.

Example 3 Silicic acid fine powder synthesized by dry method (Aerodi/l/RY
200, specific surface blood transplantation approximately 20h2/g; 7 engineering 0 Sillsha r! A) A magnetic developer was obtained in substantially the same manner as in Example 1 except that a 0.5 ffiψ portion was used.

Example 4 Magnetic properties were obtained in almost the same manner as in Example 1, except that 2 parts by weight of Bucil E (specific surface area: 90ts'7g: 11 manufactured by Shiriki Co., Ltd.) was used in the silicic acid fine powder synthesized by a wet method. A developer was obtained. □ Comparative Example 1 Only 0.4 part by weight of silicic acid fine powder (Aerosil R972, specific surface area: 12h2/g; manufactured by Aerosil Co., Ltd.) synthesized by a dry method was externally added to 100% q part of the same magnetic toner as in Example. The mixture was mixed to obtain a magnetic developer.

Comparative Example 2 Magnetic toner 103 similar to Example 1, with oxidized mangaf (m) (Mn; 13. Tokyo Kasei reagent grade 1) 0.
A magnetic developer was obtained by externally adding and mixing only 4 parts by weight.

A negative electrostatic image is formed on a selenium photoreceptor using a conventionally known electrophotographic method, and this is powder-developed using a magnetic brush method using various developers listed in L to create a toner image, which is then printed on paper. Transfer and heat fix. This method uses normal temperature and humidity (25°C, 6°C).
Table 1 (normal temperature and humidity) and Table 2 show the image evaluation results under various environmental conditions: 0% RH), high temperature and high humidity (35°C, 85% RH), and low temperature and low humidity (15°C, 10% RH). In the table 0 shown in (high temperature and high humidity, low temperature and low humidity), O indicates good, Δ indicates slightly poor, and × indicates poor.

In each example, the obtained transferred images were all sufficiently dark from the first sheet 11, and there was no fog at all, and the developer flying around the first image +'f! 1. A good image with high resolution and no distortion was obtained. Further, transferred images were continuously created and durability was examined, and the transferred images after 30,000 sheets were no inferior to the initial images. At that time, so-called filming development, in which developer adheres to the surface of the photoreceptor and causes an adverse effect on latent image formation, was not observed at all, and no problems were found as in Cleaning Y.

In addition, even when the environmental conditions are set to high temperature and high humidity (35°C, 85% RH) and low temperature and low humidity (15°C, 10% RH), a satisfactory image can be obtained that is almost the same as that at normal temperature and humidity. I got some good 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 solid rings were rough. As for durability, the C degree decreased to 0.33 after 30,000 sheets. Further, from around the io and ooo sheets, the toner material formed a film in the form of thin stripes 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 C degree 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 rise was unstable and it took about 100 sheets to saturate to a constant density. Further, the density tended to decrease slightly under high temperature and high humidity conditions and when 30,000 sheets were printed in a durability test. Also, filming started occurring around the to and ooo sheets.

[Effects of the Invention] As explained above, the magnetic developer of the present invention has a stable and uniform negative charging property, and enables development and transfer faithful to the latent image. In other words, there is no toner adhesion in the background area during development, that is, there is no fog or toner scattering around the edges of the latent image, a high image C degree is obtained, halftone reproducibility is good, and image density is improved. There is no rise 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 manganese 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.