JPH02217866A - Developer - Google Patents

Abstract

PURPOSE:To stabilize the triboelectrostatic chargeability of the developer and to form the developer so as to exhibit uniform positive chargeability even under various environments by incorporating a carbon black treated by a specific silicone oil into the developer. CONSTITUTION:The developer is so formed as to contain the carbon black treated with the silicone oil expressed by formula I. In the formula, R denotes hydrogen or methyl group. The carbon black having 10 to 70mmu particle size is used as the carbon black to constitute one constituting component of the developer. Above all, conductive furnace black and oil furnace black are used. The silicone oil having <=100cps viscosity at 25 deg.C among the silicone oils is adequate for treatment of the carbon black. The developer having the positive chargeability without having a change in electrostatic characteristics even after the execution of repetitive copying over a long period of time under low humidity is obtd. in this way.

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, magnetic recording, and the like. More specifically, in the direct or indirect electrophotographic development method,
The present invention relates to an electrophotographic developer that is uniformly negatively charged, visualizes a positive electrostatic charge image, and provides a high-quality image.

[Conventional technology]

As a conventional electrophotographic method, U.S. Patent No. 2,297,691
Although a number of methods are known, such as those described in the specification of No. After the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy. Furthermore, when a process for transferring a toner image is included, a process for 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 described in No. 76 specification.

A method using a conductive magnetic toner described in US Pat. No. 3,909,258 is known.

As toners 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 μm 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 mixed with carrier particles such as glass beads and iron powder.

A charge control agent is generally used in such a toner for dry development. As the charge control agent, organic compounds such as metal-containing complex salts and dyes are mainly used. These are usually added to a thermoplastic resin, heated, melted and dispersed, and pulverized to a suitable particle size as required to produce a toner. However, these charge control agents
It has a complex structure, inconsistent properties, and poor stability.

In addition, it is easily decomposed or deteriorated due to decomposition during thermal kneading, mechanical impact, friction, changes in temperature and humidity conditions, etc., and tends to cause a phenomenon in which charge controllability is deteriorated.

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

Furthermore, since most of the charge control agents have polar groups, they are poorly dispersed in the resin, and when the charge control agents are crushed after melt-kneading, the control agents are exposed on the toner surface. Therefore, when the toner is used under high humidity conditions, it has the disadvantage that good quality images cannot be obtained because these control agents have polar groups.

In this way, when conventional charge control agents are used in toner, the amount of charge generated on the toner particle surface varies between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves. arises,
Problems such as development fog, toner scattering, and carrier contamination are likely to occur. Moreover, this problem appears as a noticeable decrease when a large number of copies are made, resulting in a result that is practically unsuitable for copying machines.

Furthermore, under high humidity conditions, the transfer efficiency of toner images decreases significantly, and many of them become unusable. Furthermore, even at room temperature and humidity, when the toner is stored for a long period of time, it may deteriorate due to the instability of the charge control agent used and become unusable.

Additionally, many developers fail to retain desirable properties for faithfully reproducing latent images over long periods of time. Even if a product exhibits desirable performance at the beginning, after continuous use over a long period of time, the product does not retain its initial characteristics and becomes unusable. In addition, fogging occurs, toner scatters around edges when copying line drawings, and image density also decreases. Other drawbacks include a decrease in image density, scattering of line images, white spots, and fog when developing and transferring under high temperature and high humidity environmental conditions.

As a method to solve these drawbacks, Japanese Unexamined Patent Publication No. 55-1
No. 20041, JP-A No. 59-34539, and the like disclose methods of adding hydrophobic colloidal silica to impart high fluidity to toner and make the charging property uniform.

Specifically, for example, fine silica powder is reacted with an organosilicon compound such as dimethyldichlorosilane, hexamethyldisilanzane, or silicone oil, and the silanol groups on the surface of the fine silica powder are replaced with organic groups to make it hydrophobic. Fine silica powder is used. Among these, silicone oil treatment is preferable as a hydrophobic treatment, as it shows sufficient hydrophobicity and imparts excellent properties to the toner when contained in the toner. has the disadvantage that, due to its high electrical resistance, the amount of charge on the toner becomes too large during long-term edge-reversing copying, leading to a decrease in density, and this tendency is particularly noticeable under low humidity conditions.

[Problem to be solved by the invention]

An object of the present invention is to provide a positively charging developer that does not change its charging characteristics even when copying is repeated over a long period of time under low humidity.

A further object of the present invention is to provide a positively charged developer capable of reproducing stable images unaffected by changes in temperature and humidity, and in particular to improve transfer efficiency without causing scattering or omissions during transfer at high or low humidity. The purpose of the present invention is to provide a developer with high quality.

Still another object is to provide a developer with excellent storage stability that maintains its initial characteristics even during long-term storage.

(Means for Solving the Problems) That is, the present invention is a developer characterized by containing carbon black treated with silicone oil represented by the following formula (I).

(Here, R represents hydrogen or a methyl group.) As the carbon black constituting a component of the developer in the present invention, those having a particle size of Iθ to 70 mμ can be preferably used. Black, oil furnace black, etc. are particularly preferred.

Among the above silicone oils, those having a viscosity of 100 cps or less at 25° C. are suitable for treating carbon black.

In the present invention, the amount of silicone oil added to carbon black is preferably 5 to 50 parts by weight per 100 parts by weight of carbon black, and particularly excellent effects can be obtained when the treatment is performed under heating.

On the other hand, the applied amount of treated carbon black of the present invention is effective when it is 0.01 to 10% by weight, particularly preferably 0.05 to 3wt! A negatively chargeable developer having excellent stability is obtained when added to the above.

As the binder resin of the toner that can be used in the present invention, known resins such as polystyrene, polyP-chlorostyrene,
Monopolymers of styrene and its substituted products such as polyvinyltoluene; styrene-P-chlorostyrene copolymer, styrene-butyl acrylate copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene- Vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , styrene-butyl methacrylate copolymer, styrene-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether copolymer, styrene-vinyl ethyl 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, polyamide, polyvinyl butyral , polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or cyclic hydrocarbon resin, aromatic petroleum resin,
Chlorinated paraffin, paraffin wax, etc. can be used alone or in combination.

In the present invention, among these resins, styrene-
Acrylic copolymers are preferably used, particularly styrene-n-butyl acrylate copolymer, styrene-n-butyl methacrylate copolymer, and styrene-2-acrylate copolymer.
Ethylhexyl copolymers and the like are preferably used.

Coloring materials used in the toner include known dyes and pigments such as carbon black, phthalocyanine blue, indanthren blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow,
Permanent yellow, benzidine yellow, etc. can be widely used.

In order to use the toner as a magnetic toner, it may contain magnetic powder. Such magnetic powder uses materials that become magnetized when placed in a magnetic field, such as iron, cobalt,
These include powders of ferromagnetic metals such as nickel, or alloys and compounds such as magnetite, γ-iron oxide, and ferrite.

The content of this magnetic powder is relative to the weight of the toner! 5~70w
T! It is.

Furthermore, it is possible to add a charge control agent to the toner of the present invention as required. Such charge control agents include negatively charged ones such as metal complex salts of monoazo dyes and metal complex salts of salicylic acid compounds. A control agent is used.

The developer of the present invention can be applied to various developing 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-53-31
Method using high-resistance magnetic toner described in JP-A-136, JP-A-54-42121, JP-A-55-1865
Examples include methods described in Japanese Patent No. 8 and No. 54-43027, a fur brush development method, a powder cloud method, a touchdown development method, an imprefusilane development method, and the like.

Further, the developer of the present invention is suitably used in an electrostatic transfer method using an electric field generated by a corona discharge 11F electric device, a contact roller charger, or the like.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

100 parts by weight of styrene-butyl acrylate (copolymer ratio = 8 = 2) copolymer, 60 parts by weight of magnetite as a magnetic material, 4 parts by weight of polypropylene wax as a mold release agent,
2 parts by weight of a chromium complex salt of a monoazo dye was mixed as a charge control agent, and the mixture was heated to 145°C in a twin-screw router.
After melting and kneading, the mixture was cooled, and the cooled material was coarsely pulverized using a mechanical pulverizer to the extent that it could pass through a wire mesh with an opening diameter of 2 mats, and then finely pulverized to about 10μ using a wind-type pulverizer Shedmill. Wind classifier Albine 100M for finely pulverized products
The powder was graded using ZR so that the volume average particle diameter was II to 13μ, and a positively charged black powder was prepared.

On the other hand, while vigorously stirring 100 parts by weight of conductive furnace black with a particle size of approximately 30 mμ, dimethylpolysiloxane (viscosity at 25°C: 40 cps) was heated.
A solution obtained by diluting 15 parts by weight four times with xylene is sprayed. While continuing to stir, the temperature of the stirring tank was raised to approximately 280°C and maintained for 2 hours. Thereafter, it was cooled to obtain dimethylpolysiloxane-treated carbon black.

0.4wt9& of the above dimethylpolysiloxane-treated carbon black was added to the black powder to prepare a developer.

This developer is applied to a commercially available copying machine (product name: NP-7550,
(manufactured by Canon). A clear image without fog was obtained, and the image reflection density was 1.35. Furthermore, in order to examine the durability of the developer at low temperatures, we tested it at 20°C.
When copying 100,000 sheets repeatedly under RHt using a document with an image area ratio of 2t as the original, images were obtained that were comparable to the initial image, and the amount of charge of the developer remained around 8μc/g. The triboelectricity was also stable. The amount of charge on the developer was measured by absorbing only the toner from the developing machine into a Faraday gauge.

On the other hand, even under a high humidity environment (30°C, 90RH!k), an image with an image density of 1.24 and no problems such as fogging was obtained.

It also showed good transferability under various environments, and no white spots or scattering of lines or images were observed.

Performance 1 Out of 1 100 parts by weight of oil furnace black having a particle size of approximately 13 mμ was treated in the same manner as in Example 1, with 20 parts by weight of methylhydrodiene polysiloxane (viscosity 70 cps at 25°C).

0.6 ml of the above-mentioned treated carbon black was added to the black powder of Example 1 to prepare a developer. This developer was used in Example 1.
When evaluated in the same manner as above, good results were obtained.

Oil furnace black with a particle diameter of approximately 60 mμ
100 parts by weight was treated with 5 parts by weight of dimethylpolysiloxane (viscosity 20 cps at 25°C) in the same manner as in Example 1 to obtain a developer. When this developer was evaluated in the same manner as in Example 1, good results were obtained.

Uragokai A Styrene-butyl methacrylate (copolymer ratio = 7:3)
100 parts by weight of the copolymer, 5 parts by weight of carbon black as a coloring agent, 3 parts by weight of polypropylene wax as a mold release agent, and 2 parts by weight of a chromium complex salt of a salicylic acid compound as a charge control agent were mixed, and the following was carried out in the same manner as in Example 1. A black powder was prepared.

Conductive furnace black with a particle size of approximately 20 mμ
100 parts by weight were treated with 18 parts by weight of methylhydrodiene polysiloxane (viscosity 30 cps at 25°C).

A toner was prepared by adding 1.0 tS of the above-mentioned treated carbon black to the Moeki black powder. 5 parts by weight of this toner and 95 parts by weight of ferrite carrier were mixed to prepare a developer.

On the other hand, a positive electrostatic latent image is formed on the selenium photoreceptor, this is developed with the above developer, and the resulting powder image is transferred to plain paper using a corona discharger. It was fixed with a heat roll fixer.

When evaluated in the same manner as in Example 1, good results were obtained.

〔Effect of the invention〕

As explained above, when a developer containing carbon black treated with silicone oil is used, the triboelectric charging properties of the developer are stabilized, and the developer exhibits uniform positive charging properties even under various environments. In particular, when the surface of carbon black is coated with silicone oil represented by the formula (I), it exhibits good positive chargeability, and the conductivity of the carbon black inside suppresses excessive charge accumulation. It is thought that it exhibits stable triboelectric charging properties even under low humidity. Therefore, by using the developer according to the present invention, it is possible to obtain clear, high-density images without fogging, and even when used repeatedly for a long period of time, the image does not deteriorate, and can be used under high temperature and high humidity conditions or under low temperature and low humidity conditions. The transfer characteristics were good even under low conditions, and it became possible to obtain images without problems such as scattering or white spots.

Claims (1)

[Claims] A developer characterized by containing carbon black treated with silicone oil represented by the following formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (Here, R represents hydrogen or methyl group.)