JPS60192964A - Manufacture of electrostatic charge image developing carrier - Google Patents

Abstract

PURPOSE:To obtain high conductivity and stability to humidity by attaching specified silicone oil to the surface of a carrier by the dipping method. CONSTITUTION:Silicone oil having repeating units each represented by the formula shown here (each of R1 and R2 is <5C lower alkyl, aralkyl, or aryl, and they may be same or different as or from each other, and R1 may be H) is attached to the surface of a conductive carrier by the dipping method, and the carrier is heat-treated at a temp. of >=100 deg.C to bake and fix the silicone oil. Said silicone oil has a viscosity of 0.65-500,000cSt, and it may be a combination of 2 or more kinds of silicone oil. It is used in 0.001-5wt% of the carrier, and when larger, the carrier increases in resistivity and becomes an insulator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a carrier for developing an electrostatic image, that is, a carrier that constitutes an electrostatic image developer together with a toner.

For example, in electrophotography, a photoreceptor made of a photoconductive element is given a uniform surface charge in a dark place, an electrostatic charge image is formed by imagewise exposure, and this electrostatic charge image is developed to form a visible image. form.

Generally, methods for developing such electrostatic images are broadly classified into liquid development methods and dry development methods.

The liquid development method uses a liquid developer made by dispersing various pigments and dyes as fine particles in an insulating organic liquid, and the dry development method uses carbon in a natural or synthetic resin. This is a developing method that uses a fine electrically conductive powder called a toner that contains a colorant such as black dispersed therein. This dry method includes the so-called bristle brush method, impression dyeing method, powder cloud method using a developer mainly containing the toner, and mixing of the toner with a carrier made of iron powder or glass beads. There are PJTiIv used as a whole body developer, magnetic brush method, and cascade method.

By these developing methods, electrostatic particles such as charged toner particles contained in the developer adhere to the electrostatic image to form a visible image. This iJ visual image is one of the best for heat, pressure, solvent vapor, etc.! Or on the photoreceptor, or on another image support such as i? The image is transferred to a f-body and later fixed.

Among the above-mentioned developing methods, the present invention is characterized in that the developer used in the dry developing method is stirred together with the toner in a gear carrier, that is, a carrier is stirred together with the toner. This relates to a manufacturing method.

[Prior art]

Generally, carriers can be broadly classified into insulating carriers and conductive carriers.

Insulating carriers are generally made of ferromagnetic materials such as iron, nickel, and ferrite, and the surfaces of the core particles are insulated with high molecular weight! ll: A typical carrier is uniformly coated with a resin. In development with a developer using this insulating carrier, no electrode effect can be expected because the carrier is insulative, and therefore strict conditions are required for development.

On the other hand, as a conductive carrier, ferromagnetic powders made of iron, nickel, ferrite, etc. are generally used. In development with a developer using this conductive carrier, since the carrier is conductive, a so-called opposed electrode effect in which the charges of the carrier are concentrated near the electrostatic charge image in the development area is obtained, which is relatively This method is preferable from the viewpoints that it is possible to develop even an electrostatic charge image with a low potential, and the conditions required for development are considerably relaxed.

Conventionally, it is known that ferromagnetic powder is used directly as a conductive carrier in order to impart high conductivity to the carrier. The powder is hydrophilic on its surface!
Because of the presence of groups, it has a high affinity for water, and therefore lacks stability against humidity and faeces, and particularly under conditions of high humidity, the development properties of the carrier, such as firefly #L properties and fluidity, are significantly reduced. However, there is a problem that the resulting visible image is inferior in resolution and has many capri.

This is because moisture in the air binds to hydrophilic groups such as hydroxyl groups on the surface of iron powder or ferrite powder, changing the surface condition of the carrier.

In addition, particularly in the production of ferrite powder, it is necessary to add a deflocculant such as sodium salt of polymethacrylic acid, as described in Japanese Patent Publication No. 53-15040. Since the sodium contained in this deflocculant remains as ions on the surface of the ferrite powder, the sodium ions also have a water-absorbing effect, and as the humidity increases, the charging characteristics and fluidity of the carrier deteriorate significantly.

For this reason, conventional methods for improving moisture resistance include coating the surface of a conductive carrier material such as iron powder or ferrite powder with a water-resistant resin such as silicone resin.

Although moisture resistance can be improved by such a method, since the conductive carrier material is coated with resin, the conductivity of this carrier material is hidden and the desired conductive carrier is not obtained. I have a problem where I can't do it.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to be able to impart excellent water repellency to a carrier without impairing the conductivity of the conductive carrier material, and to be able to manufacture it easily. It is an object of the present invention to provide a method for producing a carrier for developing an electrostatic image by which the carrier can be obtained simply and at low cost.

[Structure of the invention]

The above purpose is to coat a silicone oil having a p repeating unit represented by the following general formula [1] (hereinafter also simply referred to as "specific silicone oil") on the surface of a conductive carrier material by a dipping method. This is achieved by a method for producing a carrier for developing an electrostatic image, which is characterized by including a step of heat treatment at a temperature of .degree. C. or higher.

General formula CD R1 5i0-2 (wherein, R1 represents a hydrogen atom, a lower alkyl group having 4 or less carbon atoms, an aralkyl group, or an aryl group, and R2 represents a lower alkyl group having 4 or less carbon atoms, an aralkyl group, or an aryl group) R4 and R2 may be the same or different.) The present invention will be described in detail below.

In the manufacturing method of the present invention, a silicone oil having a repeating unit represented by the above general formula is deposited on the surface of a conductive carrier material by a dipping method using a solvent or without using a bath agent. Then, if necessary, a drying treatment is performed, followed by a heat treatment at a temperature of 100° C. or higher to bake and fix the specific silicone oil on the surface of the carrier material, thereby producing a conductive carrier for developing electrostatic images.

In the general formula (1), 1 in the formula represents a hydrogen atom, a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, propyl group, butyl group), an aralkyl group (e.g. benzyl group, phenethyl group, etc.) ), or an aryl group (e.g. phenyl group, tolyl group, xylyl group, naphthyl group, anthryl group, etc.), and R2 is a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, propyl group, butyl group). , an aralkyl group (e.g., benzyl group, phenethyl group, etc.), or an aryl group (e.g., phenyl group, tolyl group, xylyl group, naphthyl group, anthryl group, etc.), and has, for example, a repeating unit represented by the following structural formula: 0 (1-1) 5i-0- CR3 (I-2) 8i-0- 5i-U- Ck'2CF20F5 (1-4) H6! 8i-0- CR2 (I-5) H6 8i-0- (1-6) 8i-0- (1-7) 5i-0- (1-8) 2H5 ■ -Si-0- H3 Also, the above The viscosity of specific silicone oils is controlled by the number of repeating units, and the viscosity is usually from 0.65 to 500,000 centistokes. Further, the specific silicone oil may have at least two types V of repeating units represented by the general formula [■] n1J.

In addition, among the specific silicone oils mentioned above, examples of specific products sold in "■" include [KF-99j.

rKfi'-50J, I-KI''-54J, rKF-5
6j, rK Rui-69J.

1'-Kl-96J, rKF-92J, rKr-96
5J (manufactured by Shin-Etsu Silicone Co., Ltd., rS) l-1107
J, [5) 1-8400J.

[5H-8700J, rsH-200J, l'-8RX
-310J.

"Pi, X-4 (J4J, IF), X-407J, [5
H-510J.

rsI4-55uJ, rsH-750J (or more tone/
Silicone company! R), etc.

The quality of the conductive carrier material used in the present invention can be those conventionally used for this type of use, such as iron powder that has been treated with iron powder or iron powder that has not been treated with oxidation. In terms of structure, there are ferrite powders, which are usually represented by MeO-1!1e205 (Me represents Fe, Ni, Cu, and other metal atoms), nickel powders, and others. Powdered powder or ferrite powder is preferred. The particle size of this carrier material is usually 30
~1000 μm, preferably 50-500 μm.

Next, specific examples of the manufacturing method of the present invention will be described in detail.

(1) Adhesion treatment process In the treatment of depositing the specific silicone oil on the surface of the conductive carrier material, a dipping method among various coating methods currently known is used. Specifically, there is a method in which a carrier material is poured into a specific silicone oil to be coated, stirred, and then pulled out, or a method in which a specific silicone oil is added to Chiyaria material and mixed and stirred, and the carrier material is a fine powder. Therefore, the latter method is preferable.

The specific silicone oil may be applied to the surface of the carrier material, but it is preferable to apply it thinly and uniformly to the surface of the carrier material. The ratio of the specific silicone oil used is usually 0. (101
-5% by weight, preferably 005-2% by weight. If this ratio is too large, the specific resistance of the obtained carrier increases and it tends to become insulating, which is not preferable.

The specific silicone oil may be used alone as it is, or may be diluted with a solvent to improve adhesion. Examples of such solvents include aromatic hydrocarbons (toluene, xylene, etc.), halogenated hydrocarbons (trichlorethylene, perchloroethylene, etc.), ketones (acetone, methyl ethyl ketone, etc.),
Others can be mentioned. When processing this solvent, it is preferable to avoid using such a solvent in the drying or heat treatment described below, or if there is a risk of ignition.
In this case, it is desirable to use a nonflammable bath agent such as trichlorethylene or perchlorethylene. The proportion of the bath agent to be used is preferably such that when the specific silicone oil is diluted, the concentration of the specific silicone oil is 1 to 20%.

When using a repeating unit consisting of one repeating unit in which R1 is a hydrogen atom in the general formula [1] as the specific silicone oil (F- means that in the heat treatment described below, the heating temperature is reduced or the heating time is shortened, etc.). In order to achieve
A catalyst may be added to the specific silicone oil. Such catalysts include, for example, iron octoate,
Examples include diptyltin dichlorate, dibutyltin dichloro, diptyltin maleate, and the like. The proportion of this catalyst to be used is usually within 10% by weight with respect to the specified silicone oil, but this proportion 'f: can be changed by changing the proportion 'f' and the heat treatment B to be described later. It is possible to control the heating temperature or heating time with a relatively large degree of freedom.

Examples of specific devices that employ the principle of the immersion method include:
Ribbon-type mixers (such as the "ribbon-type mixer" (manufactured by Hosogi Ironworks WT)), screw-type mixers (vertical type) (such as Nauta Mixer-J (61i [manufactured by E-use Ironworks)], fluidization type Mixing machine (“Henschel Mixer” (Mitsui Miike Manufacturing Co., Ltd.)
etc.), high-speed stirring type granulators (manufactured by Nrointo Sangyo Co., Ltd., Nara Kikai Seisaku Shin, etc.).

(2) Drying treatment process If a solvent is used in the adhesion treatment process, drying treatment with air drying or a dryer should be performed to volatilize and remove the solvent before applying it to the heat treatment process described below. is preferred. Furthermore, if no solvent is used in the adhesion process, this drying process can be omitted. This drying place 8! The drying temperature and drying time vary depending on the type of solvent used in the adhesion treatment process, fireflies, etc., but the drying temperature is usually 40-150°C, and the drying time is usually 5-150°C.
It is 180 minutes.

Specific devices that can be used in such a drying process include, for example, a direct IJ heating type rotary dryer (manufactured by Okawara Seisakusho, Koeitama Tekko Co., Ltd., etc.), an indirect heating type rotary dryer (manufactured by Okawara Seisakusho, Ltd., etc.), μzawa Tekkosha M, etc.), fluidized bed dryers (Okawara F9r, etc.), vibration dryers (Shindo Denki Co., Ltd., etc.), conduction heating dryers (Hataka Kikai Co., Ltd., Nara Kikai Seisaku'PJT#) (manufactured by Boas, etc.), band dryers (manufactured by Okawa & Seisakusho, etc.), etc. Among these, the "paddle dryer" (manufactured by Nara Kikai Seisakusho), which is a conduction heating type dryer, can be mentioned. and "Multistage Grate Dryer" (manufactured by Hoas) can be preferably used because of their low operating costs.

In addition, it is possible to carry out drying treatment using the high-speed agitation granulation method described as an example of a device that can be used in the adhesion treatment process, or by passing steam. After the deposition process, a subsequent drying process can be performed using a device.

(3) Heat treatment process In the heat treatment V of the carrier material whose surface is coated with the specific silicone oil, the heating temperature is preferably 100°C or higher, but preferably 100°C to 60°C.
It is heated at 0°C, or roughly 100-500°C. If the heating temperature is less than 100° C., the specific silicone oil will not be sufficiently fixed to the surface of the carrier material, making it impractical in terms of moisture resistance. Further, unnecessarily increasing the heating temperature is not preferable because the energy cost required for the heat treatment increases. Also, the general formula [
1], when a specific silicone oil in which R1 is not a hydrogen atom is used, the heating temperature is preferably 150° C. or higher.

When a catalyst is used in the deposition process,
The heating temperature can be reduced considerably, e.g.
By performing the heat treatment at a temperature of ~200°C, the specific silicone oil can be baked and fixed to the surface of the carrier material to a sufficient degree for practical purposes. Heat treatment
The time required for this step is usually 1 to 180 minutes, but when a catalyst is used as described above, it can be considerably shortened to, for example, about 1 to 10 minutes.

Examples of devices that can be used in such heat treatment include an electric oven, a constant temperature bath, and a rotary kiln. Among these, a rotary kiln is preferably used because continuous processing is possible.

The carrier obtained by the production method of the present invention is a conductive carrier, and its specific resistance must be, for example, 1012 Ω·α or less, but practically it is desirable that it be 104 to 1012 Ω·α, preferably 104 to 1010 Ω·σ. . The specific resistance of this carrier can be measured, for example, as follows. As shown in FIG.
A cylindrical container 2 with openings at both ends made of insulating resin arranged
The carrier powder sample to be measured is accommodated in the cylinder of the container 2, and the upper part' has a convex portion 31 having an outer diameter that matches the inner diameter of the cylinder of the container 2.
The protrusion 31 of the electrode 3 is pushed into the cylinder of the container 2 to sandwich the carrier powder sample between the lower electrode 1 and the upper electrode 3, and a DC power source 4 is connected between the lower electrode 1 and the upper electrode 3. It can be determined by connecting an ammeter 5 and measuring the current flowing between the lower electrode 1 and the upper electrode 3 with the ammeter 5.

For example, specific measurement conditions are as follows.

Measurement cross-sectional area of 0 carrier powder sample...
・-・・Load due to 1 cm20 upper electrode 3・・・−
・・・−・−・・・・−・・・−・・・・−・・・・
IKfO DC' voltage applied by 4vc...
......10 to 100■ The toner constituting the developer together with the carrier obtained by the present invention is attached to the resin.
It is made by dispersing a coloring agent, and various thermoplastic resins are used as the binder resin. Specific examples include styrene, parachlorostyrene,
Styrenes such as α-methylstyrene; methyl acrylate, ethyl acrylate, 11-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate , methacrylic acid 2-
(1-methylene aliphatic monocarboxylic acid esters such as ethylhexyl; vinyl nitriles such as acrylonitrile and methacrylonitrile; 2-vinylpyridine,
- Vinylhyridines such as vinylpyridine; Vinyl ethers such as vinyl methyl ether, vinyl isophthyl ether/L-fz; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl impropenyl ketone; Ethylene, propylene, isoprene, butadiene, etc. Unsaturated hydrocarbons and their halides, Shio Coll.
- Polymers of monomers such as sumo wrestlers and halogenated unsaturated hydrocarbons such as chloroprene, copolymers obtained by combining two or more of these monomers, and mixtures thereof, or, for example Non-vinyl curly thread resins such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, and polyether resins, or mixtures of these with the above vinyl resins (!- to name a few) can.

Further, as the coloring agent, for example, carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, cyanine blue for the lid, or a mixture of cholera. can be mentioned.

Further, in the carrier obtained by the present invention, additives for improving properties may be mixed and added.
Specific examples include fine powders of hydrophobic silica, pigments, dyes, and the like.

〔Effect of the invention〕

In the manufacturing method of the present invention, the silicone oil is applied to the surface of the conductive carrier material and then heat-treated, so that the fired product of silicone oil is fixed to the surface of the carrier material. As will be understood from the description of the examples below, the conductivity of the conductive carrier material is sufficiently preserved without being impaired, and as a result, a carrier having high conductivity can be obtained. Moreover, as shown in Figure 2, the fired product of silicone mail has oxygen atoms in the siloxane bonds derived from silicone oil bonding with hydrophilic groups such as -OH groups on the surface of the carrier material, thereby blocking the hydrophilic groups. Furthermore, by orienting the oxygen atom in the siloxane bond toward the optical surface side of the carrier material, the hydrophobic group bonded to the silicon atom in the siloxane bond becomes oriented outward, resulting in a large carrier size. As a result, by the method of the present invention, it is possible to produce a carrier having high conductivity and excellent water repellency.

The reason why the conductivity of the conductive carrier material is not impaired is because the fired silicone oil is fixed to the surface of the conductive carrier material, but this does not affect the surface of the carrier material like ordinary silicone resin. It is presumed that this is because it is not something that sticks to the gutter and hides it. By applying heat treatment, the silicone oil can be made to adhere to the surface of the carrier in the manner described above, and if the heat treatment is insufficient, the adhesion treatment with silicone oil is meaningless. Become.

In the method of the present invention, 1 is that since the silicone oil is easily deposited on the surface of the carrier material, the deposition process can be reliably achieved by the dipping method, and as a result, the deposition process is characterized by particularly advanced technology. can be easily carried out, and the apparatus for carrying out the immersion method has a simple structure, and equipment costs and setback costs are low.As a result, the excellent carriers described above can be manufactured easily and at low cost. be able to.

〔Example〕

The present invention will be described in detail below, but the present invention is not limited to these Examples.

Example 1 151 of dimethylpolysiloxane "KF-96J 14 manufactured by Etsu Silicon Co., Ltd." was dissolved in 200 m of trichlorethylene as a solvent.
4 to prepare a deposition treatment solution. Next, 5Kf of pulverized iron powder jEFVsJ (manufactured by Japan Iron Powder Co., Ltd.) was loaded into a high-speed granulation stirrer [Laboratory Matrix 1, MA-10J (manufactured by Nara Kikai Seisaku PJT), and while stirring, the above-mentioned deposition was carried out. A treatment solution was added to perform the ``'C deposition treatment.

After the adhesion treatment using the immersion method for 5 minutes, the mixed solution is dried using a conduction heating type dryer "Buddle Dryer" (manufactured by Nara Kikai Seisaku Wr.)
The sample was transferred to a drying process at a temperature of 80°C. Next, the dried material was transferred to a stainless steel vat and heated in an electric oven at a temperature of 400°C for 60 minutes to obtain a carrier.
This will be referred to as "sample carrier l."

The specific resistance of this sample carrier 1 is 1.51 in configuration 4 shown in FIG. It was measured using an I-meter. The results are shown in Table 1.

Next, the electrophotographic copying machine rU-B i
A developer was prepared by mixing toner for V-1 [J (manufactured by Konishiroku Photo Industry Co., Ltd.) 1. This developer was used completely, and the environmental conditions were: total temperature 10°C, relative humidity 20%, temperature 20°C. .

The electrophotographic copying machine rU-BixV-111j was changed to three levels: relative humidity 50%, temperature 30°C, and relative humidity 80%.
The quality of the visible image obtained by conducting a live-action test was
I researched Kabri. The results are shown in Table 1. In the first evaluation, "○" means good, "△" means practical, and "x" means not practical.

Examples 2 to 10 and Comparative Examples 1 to 2 Sample carriers 2 to 10 and comparative carriers 1 to 2 were obtained in the same manner as in Example 1, except that the manufacturing conditions were as shown in Table 1 above. When the specific resistance of these carriers was measured in the same manner, the results were as shown in Table 1. In addition, similar to Example 1 using each of these carriers ((
When a photocopy test was conducted, the evaluation of the resulting copied images was as shown in Table 1.

As can be understood from the results in Table 1, the developer using sample carriers 1 to 10 obtained by the method of the present invention can stably produce good copied images without being affected by humidity changes. In contrast, a developer using Comparative Carrier 1, which does not contain any of the specific silicone oil,
and a copy ii obtained from developer using Comparative Carrier 2 in which the heating temperature in the heat treatment was less than 100°C.
! The il- house was severely affected by changes in humidity and was unstable.

Furthermore, even when heat treatment is performed using a catalyst at a much lower heating temperature and a much shorter heating time, the resulting carrier has high conductivity and excellent moisture resistance.
With the developer using this, good-looking copied images can be stably formed without being affected by changes in humidity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view schematically showing an example of a measuring device for measuring the specific resistance of a carrier, and FIG. 2 is an explanatory sectional view schematically showing the surface of a carrier obtained by the method of the present invention. . 1... Lower electrode 2... Container 3... Upper electrode 4... DC power supply 5... Ammeter

Claims (1)

[Claims] 1) It includes the step of applying a silicone oil having a repeating unit represented by the following general formula [■] to the surface of a conductive carrier material by a dipping method and heat-treating it at a temperature of 100°C or higher. A method for producing a carrier for developing an electrostatic image, characterized by: General formula (1) % formula % (wherein 1 represents a hydrogen atom, a lower alkyl group having 4 or more carbon atoms, an aralkyl group or an aryl group, R2
represents a lower alkyl group, aralkyl group, or aryl group having 4 or less carbon atoms, and R1 and R2 may be the same or different.)