JPS5825641A - Developer - Google Patents

Abstract

PURPOSE:To provide a toner for developing a negative latent image adapted to a pressure fixing method, by mixing fine particles containing an ethylenic olefin polymer and fine silica powder synthesized by the wet process further with a fine silica powder synthesized by the wet process. CONSTITUTION:An ethylenic olefin polymer, a colorant, and fine silica powder synthesized by the wet process and containing >=85wt% silica having 5-11pH value of 4wt% dispersion in water, preferably 7-9, and 0.01-10% sodium expressed in terms of Na2O, necessary amount of sodium to keep pH of an aq. dispersion system being 0.1-2.0%, and when needed, another binder or additive are melted and kneaded, granulated by the known process, and classified to obtain 1-35mum fine particles, and these particles are further mixed with fine silica powder synthesized with the wet process to prepare the desired developer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer for developing electrical latent images in electrophotography, electrostatic recording, electrostatic printing, and the like. More specifically, the present invention relates to a developer that visualizes a negative electrostatic charge image and provides a high-quality image.

Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,69
Although many methods are known, such as those described in Japanese Patent Publication No. 42-239104 and Japanese Patent Publication No. 43-24748, they generally utilize a photoconductive substance and apply electricity to a photoreceptor by various means. After forming a target latent image and developing the latent image with toner at the doctor's office, the toner image is transferred to a transfer material such as paper as necessary, and then fixed by heat, pressure, or solvent vapor, etc. to create a copy. This is what you get. Further, when a step of transferring a toner image is included, a step of removing residual toner on the photoreceptor is usually provided.

Development methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063, and the magnetic brush method described in U.S. Pat. No. 2,618,552. Cascade development method and 2,221.7
Powder cloud method, fur brush development method, impression development method described in 7 fi specification, JP-A-54-4
Methods such as those described in Japanese Patent No. 2141 and Japanese Patent No. 55-18656 are known.

As a developer toner applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 microns are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually glass beads,
It is used mixed with carrier particles such as iron powder.

On the other hand, various fixing techniques using heat, pressure, and solvents have been invented in the past to fix toner images on a support. Among these methods, the method using a solvent is superior in that the toner can be completely fixed with less energy, but there is a risk that solvent vapor may leak from the copying machine. Furthermore, the most common method of fixing using heat requires a large amount of energy, requires a long time to heat the fixing device to a temperature that can fix the toner, and has problems such as the temperature around the fixing device becoming higher than necessary. There are drawbacks. On the other hand, the fixing method using pressure has the disadvantage that it is difficult to perform perfect fixing, but has the advantage that it requires less energy and does not require waiting time for copying.

In the pressure fixing method, a toner material with low tackiness, high cohesive force, and low coefficient of friction is required, and ethylene-based olefin polymers such as polyethylene are known as such toner materials. . However, at present, it is difficult to obtain a toner suitable for developing a negative latent image using polyethylene.

Conventionally, amine compounds, quaternary ammonium compounds, and organic dyes, particularly basic dyes and salts thereof, are well known as charge control agents for producing positively charged toners. Specific examples thereof include nihahenzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine vitrochloride, zafranin γ, and crystal violet. In particular, nigrosine base and nigrosine hydrochloride are often used as positive charge control agents. These act relatively effectively on toner materials used in heat fixing systems, such as polystyrene.

Although it is possible to make the toner positively chargeable, it is not effective at all when using an ethylene-based olefin polymer.

Therefore, an object of the present invention is to provide a toner for developing a negative latent image using an ethylene-based olefin polymer, which is a material suitable for pressure fixing.

That is, the present invention provides a toner obtained by mixing fine particles containing at least an ethylene-based olefin polymer and a fine silicic acid powder synthesized by a wet method, and further a fine silicic acid powder synthesized by a wet method. It is something.

The ethylene thread olefin polymer used in the present invention is a monopolymer of ethylene-based olefin monomers such as ethylene, propylene, and butylene, or a copolymer mainly composed of them, such as polyethylene,
Examples include polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, and ethylene-butyl acrylate copolymer. Among them, those with a melt viscosity of 10 to 1 at 140°C
04 centipoise polyethylene or an ethylene copolymer mainly composed of ethylene is preferred.

All conventionally known methods can be used to produce the wet silicic acid fine powder used in the present invention. For example, the decomposition of sodium silicate by an acid can be expressed as a general reaction formula (hereinafter, reaction formula 1 is omitted): Na! 0: x Si(%+HCf+H40→S
i02- nH,0+NaCJ and other decomposition of sodium silicate with ammonia salts or alkali salts,
A method in which an alkaline earth metal silicate is generated from sodium silicate and then decomposed with an acid to form silicic acid, a method in which a sodium silicate solution is converted into silicic acid using an ion exchange resin,
There are methods that use natural silicic acid or silicates.

The silicic acid fine powder mentioned here includes anhydrous silicon dioxide (silica), aluminum silicate, sodium silicate,
1. Silicates such as potassium silicate, magnesium silicate, and zinc silicate. Any of these can be applied, and it is desirable that the particle size is within the range of 0.01 to 2 μm as an average primary particle size.

Commercially available fine silicic acid powder synthesized by the wet method used in the present invention includes, for example, those commercially available under the following names.

Carplex Shionogi & Co., Ltd. Nip Seal Nippon Silica Toxeal, Fine Seal Tokuyama-1ll Tavitaseal Tagi Hijiruton, Silnetx Mizusawa Kagaku Starsil Kamishima Kagaku Himezil Ehime Yakuhin Thyroid Fuji Davison Kagaku Hi-sil (High Seal) Pittsburgh
hPlateGlassCo, (Pittsburgh Plate Glass) Durosil (Douq Seal) F”1illst
off-GesellschaftUltrasil(
Ultra Seal) Marquart (Fürstschuf Gesellschaft Marquart) Manosil (7)'/-ru) Hardman
and Ho1den (Hardman and Holden) I-1oesch (Herash) Chemische
Fabrik Hoesch K-G (Hiemitsusche Fabrik Hoesch) Sil-8tone (Silua X To 7) 8toner Ru1) ber C
o.

(Stoner Lover) Nalco Na1co Chem, C
.

(Narco Chemical) Quso I'hiladelphia
Quartz Co.

(Philadelphia Quartz) Santocell (Santocell A-) Mon5a
nto Chemical Co.

(Monsanto Chemical) Imsil (Immuno/l/) l1linois
Minerals Co.

j (I ~ Nois Mio, Sil) CalciumSilikat Chemisch
ePabrikHoesch.

(Calcium Silica-1・)K-G
Calsil Fiillsto
ff-GesellschaftMarquart (
Fortafil (7 Alterfil) Imper
ial Chemical Industries,
Ltd.

(Imperial Chemical Industries) Microcal Joseph C
rosfield &: 5oz.

Ltd, (Jiecef Crossfield and Sons) Manosil (7 Nosil) Hardman a
nd l-1o1den (Hardman and Holden) Vullcasil (Purkasil) Farbenfa
briken Bayer.

A, -Q, (Falpenfupuriichiken Bayer) Tufknit Durham Ch
emicals, Ltd.

(Doulham Chemicals) Silmos Shiraishi Kogyo Starex Kamishima Kagaku Furikosil Takihii These can be used after being adjusted to have an average primary particle size in the range of 0.01 to 2μ.

In the present invention, as described in item 11, silicic acid fine powder synthesized by a wet method is used and exhibits an effect. Among such wet method silicic acid fine powders, the silicic acid fine powder Particularly desirable is one containing 85% or more of 5i02.

In addition, the wet process silicic acid fine powder used in the present invention, which exhibits stable and strong positive chargeability, has minute pores in its internal structure, unlike the dry process silica that has been conventionally used in toners.
It contains many water molecules bonded to the silanol groups on the pore surface by van der Waals forces. Unlike the water adsorbed on the surface of dry process silica, the water content in the internal structure of such fine silicic acid powder remains relatively stable even when the environment changes. The reason why the toner containing the silicic acid fine powder synthesized by the wet method, which is a feature of the present invention, exhibits stable positive chargeability in the environment is due to the stable water content in the internal structure. It is thought that this is because of this. The moisture contained in the internal structure of the silicic acid fine powder is expressed as the weight loss rate (ignition loss) after heating for 2 hours at a temperature of 900''C, for example, and the silicic acid fine powder used in the present invention The ignition loss of the body is 0.1 to 10% (preferably 0.3 to 10%).
(3%) is particularly desirable.

The silicic acid fine powder synthesized by the wet method stably and strongly positively charges the toner of the present invention, but as a result of studying the silicic acid fine powder synthesized by the wet method, it was found that the silicic acid fine powder synthesized by the wet method could be submerged in water. It has become clear that it is preferable to use a silicic acid fine powder that has a pH value of 5 to 11 (more preferably 7 to 9) when dispersed at 4% by weight. This is thought to be influenced by the various elements contained in the raw materials used to synthesize the silicic acid fine powder or in the processing agents used during the synthesis process, and the inclusion of alkali metal elements has a favorable effect. It is thought that there are. Among them, those that have an appropriate amount of sodium ions mixed in! Experiments have revealed that it has an effective effect on 1). In order to positively and stably charge the toner, it is particularly preferable to use silicic acid that satisfies the above pH conditions and contains an appropriate amount of sodium ions, and the preferred sodium content that provides the above 1) H value is is 0.01 to 10% in terms of Na2O. this is,
5 near the surface of the silicic acid fine powder added to the toner
This is because the sodium ions mixed into the iOz lattice or the sodium ions attached to the surface of the silicic acid fine powder are effective in forming stable positive charges through interaction with the adsorbed moisture inside or on the surface of the fine powder. Conceivable.

Specifically, among the silicic acid fine powders synthesized by the wet method used in the present invention, the pH of the water dispersion system is in the range of 5 to 11.
0.01 to 1O% (the sodium content necessary to maintain a particularly preferable pH of the aqueous dispersion is 0.01% to 10%).
．． It is preferable to use silicic acid fine powder containing 1 to 2.0%).

Examples of particularly preferred silicic acid fine powders synthesized by a wet method used in the present invention will be briefly described. Of course, this example does not limit the scope of the claims of the present invention.

Table 1 Furthermore, the surface of the silicic acid fine powder synthesized by these wet methods may be treated with an organic substance before use.

In the present invention, the silicic acid fine powder exists in the form of being dispersed inside the toner particles and in the form of being attached to the surface of the toner particles, and the latter mainly exhibits the excellent effects described in F+fl.

Since the ethylene olefin polymer of the present invention is a so-called sharp melt type binding material, it is difficult to maintain a high melt viscosity of the binding material when dispersing a coloring material, and the dispersibility of the coloring material is poor. It tends to get worse. In this respect, the silicic acid fine powder mixed into the toner particles in the present invention is extremely effective in keeping the melt viscosity high.
This improves the dispersibility of the colored substance.

The developer of the present invention can be produced by various known methods, but
An ethylene olefin polymer, a colored substance, a fine silicic acid powder synthesized by a wet method, and other binding substances and additives as necessary are melt-kneaded, granulated by a known method, and then classified. It is preferable to obtain fine particles having a weight of about 1 to 35 weight, and further mix the fine particles with silicic acid fine powder synthesized by a wet method.

In the present invention, the fine particles contain 10% by weight or more (preferably 30% by weight or more, particularly preferably 60% by weight or more) of an ethylene olefin polymer and 5 to 40% by weight (preferably 7% by weight or more). ~35
(particularly preferably 10 to 30 weight percent) of silicic acid fine powder synthesized by a wet method, and further contains 0.1 to 30 percent by weight based on the weight of the fine particles.
It is preferable to contain 10 weight percent (preferably 0.3 to 7 weight percent, particularly preferably 0.5 to 5 weight percent) of silicic acid fine powder synthesized by a wet method.

Other binders that can be used in the toner of the present invention include styrene thread polymers such as polystyrene, styrene-acrylic ester copolymers, styrene-methacrylic ester copolymers, and styrene-vinyltoluene copolymers. Coalescence, acrylic resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, 7: s-7-le resin,
Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

As the coloring substance used in the toner of the present invention, conventionally known carbon black, iron black, and other dyes and pigments can be used. However, conventionally known additives as positive charge control agents can also be used in combination with the silicic acid fine powder synthesized by the wet method used in the present invention. Various dyes include, for example, penzyldimethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigrosine base, nigrosine hydrochloride, safranin gamma and crystal violet.

Further, in order to use it as a magnetic toner, it may contain magnetic powder. Such magnetic powders include materials that are magnetized when placed in a magnetic field, powders of ferromagnetic metals such as iron, cobalt, and nickel, or magnetite and hematite.

There are alloys and compounds such as ferrite. The content of this magnetic powder is 15 to 70% by weight based on the weight of the toner.

Furthermore, the developer of the present invention may contain iron powder depending on the package.

It is mixed with carrier particles such as glass beads, nickel powder, ferrite powder, etc. and used as a developer for electrical latent images. The developer of the present invention can be applied to various development methods. For example, magnetic brush development method, cascade development method, method using conductive magnetic toner described in U.S. Pat. No. 3,909,258, JP-A-53-3113
A method using a high-resistance magnetic toner described in Publication No. 6.

JP-A-54-42141 and JP-A-55-18656.

There are methods described in JP-A No. 54-43027, fur brush development method, powder cloud method, impression development method, etc.;
Particularly preferred is the method using an insulating toner described in Japanese Patent Publication No. 55-18656. That is, an electrostatic image holder that holds an electrostatic image on its surface and a developer carrier that carries an insulating magnetic developer on its surface are arranged with a certain gap between them, and the insulating magnetic developer is placed on the developer carrier. In this method, the insulating magnetic developer is supported on the electrostatic image carrier to a thickness thinner than the gap, and the insulating magnetic developer is transferred to the electrostatic image carrier under the action of a magnetic field.

The basic structure and features of the present invention have been described above, but
The method of the present invention will be specifically described below based on Examples. However, this does not limit the embodiments of the present invention in any way. The numbers of parts in the deaf examples are parts by weight unless otherwise specified.

<Example 1> A mixture consisting of 100 parts by weight of zinc oxide, 20 parts by weight of styrene-butadiene copolymer, 40 parts by weight of a-butyl methacrylate, 120 parts by weight of toluene, and 4 parts by weight of 1% rose bengal methanol solution was milled in a ball mill. 6 hours of minutes worked out.

This was applied to a 0.05 mx thick aluminum plate using a wire bar so that the dry coating thickness was 40 μm, and the solvent was evaporated with hot air to create a zinc oxide binder photoreceptor in the form of a drum. . This photoreceptor was subjected to a corona discharge of -61 V to uniformly charge the entire surface, and then an original image was irradiated to form an electrostatic latent image.

The developer carrier was a stainless steel cylindrical sleeve with an outer diameter of 50 mm. The sleeve surface magnetic flux density was 700 gauss, and the distance between the ear cutting blade and the sleeve surface was 0.2 gauss. This sleeve rotation magnet fixation (sleeve circumference is the same as that of the drum, rotation direction is opposite) type developing device is installed with a distance between the photosensitive drum surface and the sleeve surface of 1i7 [c 0.25 mtg.
An alternating current of 400 Hz lOOOV and a direct current bias of -150 V were applied to the sleeve.

Polyethylene v:y (PE130, Hoechst N
) 100? ml' Methylene blue chloride 5 parts Magnetite 60 parts Wet process silica and Pusil E (manufactured by Nippon Silica) 15 parts The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After allowing the mixture to cool naturally, it is roughly pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain an average particle size of 1.
A fine powder of 0 to 20μ was obtained.

To this fine powder, 1.0% by weight of the above-mentioned wet process silica carnibutyl F3R was added to the developer, and the mixture was mixed in a Henschel mixer to form a developer.

This was subjected to the electrostatic corona of the developing machine according to the method described above to obtain a transferred image on plain paper. The image had a high optical reflection density of 1.4, had no capri, and was clear with high resolution. Furthermore, when this image was applied to a pressure fixing device consisting of two hard chrome-plated metal rollers, it was completely fixed. The fixing pressure was 151 cg/crn. Furthermore, when 10,000 copies were made continuously using this developer, the images obtained were of exactly the same quality as the initial images, and there was no deterioration of the developer or contamination of the developing sleeve, and the results were good. . Next, the environmental characteristics of this developer were investigated. When an image was obtained under the conditions of 15° and 15% RH, the image density was 1.30, there was no capri, and the image was equivalent to the current image at f5 at normal temperature and humidity. Also, 35°085
Even under the conditions of %R and H, the image density was sufficiently high at 1.25, and the transfer efficiency was excellent at 85 Jb.

The resolution is also excellent, and the excellent environmental properties of this developer are recognized.

<Example 2> Carbon black
5 parts The above material was prepared in the same manner as in Example 1, with an average particle size of 10μ.
A fine powder was obtained. To this fine powder, 0.6% by weight of the above-mentioned wet method silica carplex #1120 was added to the above-mentioned fine powder, and further EF"V250/400
(Iron powder manufactured by Nippon Iron Powder) and 80 parts of the powder were mixed well to prepare a developer. This was applied to a developing machine consisting of a sleeve having magnetic poles, and magnetic brush development was performed using a latent image formed on the same photoreceptor as in Example 1. When the copied image was transferred to plain paper and observed, a high-density image with high resolution and no capri was obtained (image density: 1.28). In continuous copying using this developer, the image after 1000 sheets was completely the same as the initial image. When the same environmental characteristics as in Example 1 were observed, the image density was 1.
25.35゛C85 Baba R and H had a value of 1.20, indicating that the development and transfer characteristics did not change due to changes in the environment.

In order to investigate the dispersion state of carbon black and wet silica in this crushed developer, transmission electron microscopy of a section of the powder was performed, and it was found that the silica and carbon black were extremely uniformly dispersed. Do you get it.

[Comparative Example 1] A developer was prepared and developed in the same manner as in Example 1, except that the wet process Silicanibucil ER was not used during kneading and the dry mixing was not performed. As a result, an extremely thin reversed image was obtained. obtained, and did not exhibit positive chargeability.

[Comparative Example 2] In Example 2, wet process silica, Carplex 4#
1120 instead of dry method silica, Aerosil 42
Did you do anything other than adding 00 (Japan Aerosil Co., Ltd.)? li2
When a developer was prepared and developed in the same manner as above, only an extremely dark reversed image was obtained.

Sender Canon Co., Ltd. 245-

Claims (1)

[Claims] A developer comprising a mixture of fine particles containing an ethylene-based olefin polymer and fine silicic acid powder synthesized by a wet method, and fine particles of silicic acid synthesized by a wet method.