JPH0273362A - Denshi photographic developer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic developer used for developing electrostatic images formed in electrophotography, electrostatic recording, electrostatic printing, etc. It is related to.

[Conventional technology]

Generally, the developer for electrostatic image development in electrophotography is 1
- The toner must be charged to a charge amount of 100 μc/g, and in order to stably achieve good development, the toner must have the property of being always charged with a constant charge amount. I have to keep it up.

[Problem to be solved by the invention]

However, in the case of conventional electrophotographic developers of this type, when applying the amount of charge that determines development, between the toner and the carrier in the component magnetic brush development method, and between the toner and the carrier in the component magnetic brush development method and the toner in the component magnetic and non-magnetic development methods. and toner or!・It was extremely difficult to obtain a constant high image quality because the amount of frictional electrification between the roller and the sleeve varied greatly depending on environmental conditions, especially changes in humidity.

Furthermore, specifically, especially in the case of a two-component magnetic brush development system, when the humidity is high, the amount of frictional charge between the developers described above decreases, causing trailing and fogging, and when the humidity is low, There have been problems in that the amount of triboelectric charge between the developers increases, resulting in a decrease in image density and an increase in background smearing.

Furthermore, in the -component magnetic and non-magnetic development systems, the resistance value required for development cannot be maintained both at high humidity and low humidity, resulting in deterioration of image quality.

Furthermore, even if it were possible to maintain a constant image quality, slight variations in the composition and manufacturing process can greatly affect the charge stability of the developer, making it difficult to maintain a constant charge amount against environmental changes. In fact, it was accompanied by great difficulties.

Historically, in order to ensure the amount of charge required for development, conventional electrophotographic developers have been designed to use charging characteristics that produce an excessive amount of charge. Not only does the charging impact cause a significant decrease in image density, but also the increase in fog is significantly reduced. In this case, in a two-component developer, a so-called carrier flying phenomenon occurs in which the carrier adheres to the electrostatic image support as well as image deterioration, and there is a risk of causing QT ffA such as damaging the photoreceptor surface and the fixing roller. there were. Also,
- Highly charged in component-based developers! Cohesiveness due to self-charging increases, leading to a decrease in conveyance within the developing machine and a significant deterioration in image quality due to the inability to form a uniform toner layer on the developer carrier. There was a problem.

The present invention has been made to solve the conventional problems as described in -1-, and is intended to have stable charging characteristics at all times without being affected by environmental conditions such as outside temperature and humidity. The first object of this invention is to provide a developer with excellent image stability.

A second object of the present invention is to provide an electrophotographic developer that does not become excessively charged and can provide excellent image quality.

Furthermore, a third object of the present invention is to provide a developer that does not adhere to a charge imparting member (carrier in a two-component system, developer carrier, etc. in a -component system). .

[Means to solve the problem]

In order to achieve the objects set forth in S i 02・n
It is characterized by containing silica gel represented by the chemical formula of H2O in various embodiments described below. In other words, (a) the silica gel is contained in the resin constituting the toner, (b) the silica gel is contained in the surface layer of the toner, and (c) in a two-component development method using a carrier, the carrier surface is made into an uneven surface. (d) In a one-component developer containing magnetic powder in the toner, SiO2/nH2 is added to the magnetic powder.
The silica gel represented by the chemical formula O is adhesively bonded, or (n) the silica gel is contained by a combination of two of the above-mentioned (a) to (d). It is characterized by this.

Further, specific methods for adding the silica gel include: (1) As an addition method corresponding to (a) and (b) above, the silica gel is added internally or externally to the toner.

(2) As an addition method corresponding to (c) and (d) above, the toner is dispersed in a suitable resin and coated with a carrier for two components and magnetic powder of a component magnetic toner. Alternatively, (1) Apply to the surface of other toner contact members such as sleeves and doctor blades.

■ Mix as the third component.

Furthermore, if necessary, it is also possible to control the saturation value of the charge amount by adding an ion column antistatic agent or the like internally during kneading or externally after classification.

[For production]

The silica gel represented by the chemical formula of SiO2.nH2O has an internal moisture content that is controlled by the equilibrium water vapor pressure under any environmental conditions. In the chemical formula of silica gel, n varies depending on the environmental conditions, and is a value that is in equilibrium with the environmental conditions as the total amount of water.

The silica gel has extremely porous physical properties and a specific surface area of about 5 GOr//g. therefore,
Moisture is adsorbed by the particles inside the silica gel, and the moisture is not locally exposed to the surface, so it has the property of being easily released.

More specifically, if we consider nH2O from the perspective of a type of crystallized water, a crystal containing this crystallized water has a constant water vapor pressure at a constant temperature. When the water vapor pressure in the crystal is lower, the water in the crystal is released, which is called efflorescence, and the water vapor pressure of the saturated aqueous solution of the solid is lower than the water vapor partial pressure of the liquid that comes into contact with it. If it is small, it has the so-called deliquescent property of capturing water vapor and dissolving it in the water. Therefore, it can be said that the silica gel has properties similar to both the efflorescence property and the deliquescent property, and is a substance in which these changes occur reversibly.

In addition, the above-mentioned silica gel (Si□;, ・nHz.

)'s reversible efflorescence means that the lower the humidity, the more it evaporates, and this evaporated water plays a tribocontrolling effect between the toner and the carrier, between the toner and the toner, between the toner and the sleeve, and other areas. In addition, reversible deliquescent property means that the higher the humidity, the more moisture is absorbed, but since moisture is adsorbed inside the silica gel, there is no effect on tribo control between toner and carrier, between toner and sleeve, between toner and sleeve, etc. This means that it has the property of not having any negative effects.

In this way, by keeping the amount of water in the developer constant regardless of changes in atmospheric temperature and humidity, it is possible to eliminate the environmental dependence of the amount of triboelectric charge, maintain stability in image quality, and reduce excessive charging. Since the rate of disappearance is increasing even when electrification occurs, it is possible to immediately return to a substantially constant saturated electrification state.

The amount of silica gel having such characteristics added to the developer is determined by the absolute value of the appropriate charge amount of the developer determined by the developing machine.

〔Example〕

Examples of the present invention will be described.

Next, 131-styrene-butyl acrylate resin (Himer SBM100: manufactured by Sanbe Kasei Co., Ltd.) Silica gel (dry) 100 m2 carbon black (formerly 00: King 7,000 ft in)
<Manufactured by Ryo Kasei Co., Ltd.) Charge control agent (BONTRON S34: 1
After kneading low molecular weight polypropylene (11 parts biscol 330P, manufactured by Sanbe Kasei Co., Ltd.) by a known method, it was crushed and classified to obtain an average particle size of 13 μm.
After obtaining a toner composition of
A 0.1 mm portion of silica gel that has been sufficiently conditioned with RH and 0.0 mm of colloidal silica (R972: manufactured by Nippon Aerosil Co., Ltd.)
．． 5 parts by weight were added to carry out external addition treatment.

A ferrite carrier (FL) is added to 5 parts by weight of the toner.
150: i1 (manufactured by Hon Tetsuko Co., Ltd.)■ 00 parts by weight was added to make the two-component developer I j! I was.

L1 Kano 1 Styrene-butyl acrylate-100 city ld part resin (
Hymer SBM Hot 00: Manufactured by Sanyo Kasei Co., Ltd.) Carbon black (formerly OO: San7ju 14 part, manufactured by Ryo Kasei Co., Ltd.) Charge control agent (BONTRON S34:
After kneading low-molecular-weight polypropylene (1 part by weight, Viscoel 330P: manufactured by Kaku Kasei Co., Ltd.) by a known method, it was pulverized and classified to give an average particle size of 13 μm.
A toner composition was obtained. The surface of this was coated with finely powdered silica gel. This surface coating was performed by mixing 2 parts by weight of silica gel with 100 parts by weight of ferrite carrier (FL150, manufactured by Nippon Tetsuko Co., Ltd.) and incorporating the mixture into the uneven parts of the surface, and then adding 100 parts by weight of ferrite carrier. A two-component developer (2) was obtained.

Kashigosho 1 Styrene-butyl acrylate-1001if 1 part resin (
Prioride: Made by Gladyear) Magnetic powder Magnetite (EP75 35rltli
Part 00: Door [manufactured by 11 Kogyo Co., Ltd.] Carbon black (formerly oo: Yoq e weight part, manufactured by Ryo Kasei Co., Ltd.) Charge control agent (BONTRON NO4: 2 parts by weight, manufactured by Orient Kagaku Co., Ltd.) Polyoxyethylene glyco-0.7 weight ? J<ru(PE
G6000 (manufactured by Nippon Yushi Co., Ltd.) was subjected to cross-line classification to obtain a one-component composition with an average particle size of 11 μm, and after finely pulverizing, the silica gel, which had been sufficiently conditioned at 20°C/Go%RH, was mixed into a toner composition. 0.0% per 100 parts by weight.
3 parts by weight and 1.5 parts by weight of colloidal silica (R972, manufactured by Nippon Aerosil Co., Ltd.) were added and externally added to obtain a one-component magnetic toner (developer ■).

L5 1 Use magnetic powder whose surface has been treated with unevenness in advance with 5 parts by weight of fine powder silica gel per 100 parts by weight of magnetic powder magnetite. Styrene-butyl acrylate 100mmff resin (Prioride: manufactured by Gladyear) The treated magnetic powder Magnetite 35-layer eyepiece (EP
T500: Door FIT, business company! ! I2) Carbon black (#100: 36 parts by weight, manufactured by Ryo Kasei Co., Ltd.) Charge control agent (BONTRON NO4: 2 parts by weight, Orient Chemical Co., Ltd.) Polyoxyethylene glyco-0.7 parts by weight (PEG6)
000: L1 (manufactured by Hon Yushi Co., Ltd.) was subjected to cross-line classification to obtain a one-component composition (developer ■) having an average particle size of II μm.

Next, comparative examples for Examples 1 to 4 will be shown.

Developers i-1v were prepared from Examples 1 to 4 by removing silica gel and the surface treatment using silica gel.

After thoroughly conditioning the humidity of the developers I to II obtained in Examples 1 to 4 and the developer i-1 obtained in Comparative Example under various environments, the charged acid was measured by the blow-off method. evaluated.

The table below shows the evaluation results.

Next, the results of a printing test were performed using a laser printer (KX-P-4450: manufactured by Matsushita Electric Industrial Co., Ltd.) for 10,000 sheets using the developer I of Example 1 and the developer i of Comparative Example 1. is shown in the drawing. The print density was measured using a Macbeth reflection densitometer.

〔Effect of the invention〕

As explained above, the electrophotographic developer of the present invention is S
It contains silica gel represented by the chemical formula of i 02 ・nHzo, and as is clear from the examples in which the silica gel is contained in various ways, environmental conditions such as atmospheric humidity and temperature It is possible to ensure a stable charge amount without being affected by changes.''2.The absolute amount can be controlled according to the amount of silica gel added, so there is no possibility that the charge amount will become excessive. Can prevent 1 hit. In addition, the silica gel has both efflorescence and deliquescent properties, and furthermore, the silica gel has the property that changes in efflorescence and deliquescent properties occur reversibly.
It does not adversely affect tribo control between toner and carrier, between toner and toner, between toner and sleeve, and other areas.
The problems of conventional developers, such as not adhering to charge-imparting members, can be largely overcome.

[Brief explanation of the drawing]

The drawing is a diagram showing the results of a printing test using a laser printer using the developers of Example 1 and Comparative Example 1 of the present invention.

Claims (5)

[Claims] (1) An electrophotographic developer characterized by containing silica gel represented by the chemical formula of SiO_2.nH_2O in a toner constituent resin. (2) An electrophotographic developer characterized in that the surface layer of the toner contains silica gel represented by the chemical formula of SiO_2.nH_2O. (3) In a two-component development method using a carrier, the carrier surface is formed into an uneven surface, and this uneven surface is formed by SiO
An electrophotographic developer characterized by being coated with silica gel represented by the chemical formula _2.nH_2O. (4) A one-component developer containing magnetic powder in the toner, characterized in that silica gel represented by the chemical formula of SiO_2.nH_2O is adhesively bonded to the magnetic powder. (5) An embodiment in which silica gel represented by the chemical formula of SiO_2.nH_2O is contained in the toner constituent resin, an embodiment in which the silica gel is contained in the surface layer of the toner, and an embodiment in which the carrier surface is formed into an uneven surface and the uneven surface is formed. An electrophotographic developer characterized in that it contains the silica gel in a combination of two or more of the following embodiments: coating with the silica gel, and containing magnetic powder adhesively bonded with the silica gel. .