JPH0342470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for a two-component developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a toner for developing electrostatic images.

In general, the developer for dry developing an electrostatic image is a toner containing a magnetic material such as iron powder or iron oxide powder, a carrier such as a glass bulb, a binder resin, a coloring agent, a charge control agent, etc. Two-component developers are known, and one-component developers are known, which are comprised of a magnetic toner containing a binder resin, a magnetic material, a charge control agent, and optionally a colorant.

2. Description of the Related Art Conventionally, a technique is known in which an electron-accepting substance is contained in a toner constituting a one-component developer in order to impart chargeability to the toner.

For example, JP-A-55-70850 describes a technique for incorporating an electron-accepting substance into a one-component developer, and JP-A-57-82846 describes a technique for incorporating an electron-accepting substance into a one-component developer. Magnetic toner has electron affinity
A technique for containing an electron-accepting substance of 0.7 eV or more is described.

However, when such conventional technology is applied to a two-component developer, it not only lacks stability and uniformity of triboelectric charging, but also suffers from fogging in terms of durability, especially when forming a large number of copied images. The problem was that the image quality deteriorated.

The present invention has been made in view of the above circumstances, and its purpose is to provide a negative charge for a two-component developer that has uniform charge control properties and is free from drawbacks such as development fog, toner scattering, and developer fatigue. To provide a chargeable toner.

The above object of the present invention is to use an electron-accepting substance selected from anils and quinones whose electron affinity value exceeds the Ea value of I ₂ measured from the dipole efficiency of I ₂ benzene system into a binder resin. A negatively chargeable toner for a two-component developer, characterized by containing 0.1 to 10% by weight of carbon black with a pH of less than 5.0 based on the binder resin. It is achieved by doing so.

Examples of electron-accepting substances contained in the negatively chargeable toner for a two-component developer according to the present invention (hereinafter referred to as the toner of the present invention) include anils such as chloranil and bromoanil, benzoquinone, naphthoquinone, and anthraquinone. , dichlorobenzoquinone and dichlorodicyanobenzoquinone.

The above-mentioned exemplified compounds may be used alone or in combination of two or more, but other compounds may be used in combination as necessary.

The electron affinity value of the electron-accepting substance contained in the toner of the present invention is a value exceeding the Ea value of I ₂ measured from the dipole efficiency of the I ₂ benzene system. In this specification, the Ea value of I ₂ measured from the dipole efficiency of the I ₂ benzene system is described in, for example, RSMulliken, J.Am.
Chem.Soc, vol. 72, p. 600 (1950) and LE
Lyons, Nature, Vol. 196, p. 573 (1962) when measured by the method described, it is 1.80 eV. below,
In this specification, when an Ea value is stated, it indicates a value measured by the above measuring method.

The content of the electron-accepting substance contained in the toner of the present invention can vary over a wide range, but is generally based on the binder resin.
0.1-10% by weight, preferably 0.5-5% by weight
It is. In addition, as a method for incorporating it, usually a method is adopted in which it is contained and dispersed in the binder resin by melting and kneading, but it may be incorporated in any way as long as it can exhibit the charge control effect. For example,
An external addition method may also be used. That is, it may be added externally to the toner to coat the surface of the toner, or it may be dissolved in a solvent and mixed with carbon black to form a slurry, then dried, etc., and used to coat the surface of the carbon black.

The colorant contained in the toner of the present invention includes:
Carbon black is used, and its pH is less than 5.0. The PH value of carbon black is determined by the Japanese Industrial Standard (JIS) K6221 (Testing Method for Carbon Black for Rubber) 1975 method. That is, weigh 10 g of the sample into a beaker, add 100 ml of distilled water to the sample, cover with a watch glass, and boil for 15 minutes. At this time, a few drops of special grade ethyl alcohol may be added to make it easier to wet the sample. After boiling, the temperature is lowered to room temperature, and the supernatant liquid is removed by decanting or centrifugation, leaving a slurry. A glass electrode PH meter is placed in this slurry and measured. Note that it is of course possible to add other colorants within a range that does not impair the effects of the present invention. Examples of carbon blacks with a PH of less than 5.0 include MONARCH1300 and MOGULLREGAL400R manufactured by Cabot Co., Ltd.
RAVEN1035 manufactured by Columbia Carbon Co., Ltd.
1040, 1255, 3500, 5250, 8800, etc., and #100, MA-8, MA-11, etc. of Mitsubishi Kasei Corporation. If carbon black with a pH of 5.0 or more is used, there is a disadvantage that fog occurs in the resulting image and the image quality becomes noticeable.

The amount of carbon black added to the toner is preferably 1 to 40% by weight, particularly preferably 5 to 30% by weight, based on the binder resin.

The binder resin contained in the toner of the present invention may be any of those conventionally used in toners, such as olefin resins such as polyethylene and polypropylene, polyacrylic esters,
Acrylic resins such as polymethacrylic acid esters, acrylic acid copolymers, methacrylic acid copolymers, polystyrene, hydrogenated styrene resins, ethylene-vinyl acetate copolymers, styrene copolymers,
Vinyl resins such as vinyl chloride, vinylidene chloride, vinyl acetate, polyamide resins such as nylon-12, nylon-6, polymerized fatty acid-modified polyamide, polyethylene terephthalate/isophthalate, polytetramethylene terephthalate/isophthalate, or JP-A-57 - Polyester resins described in Publication No. 37353, alkyd resins such as phthalic acid resins and maleic acid resins, synthetic resins such as phenol formaldehyde resins, cumaron resins, and epoxy resins, natural rubber, chlorinated rubber, styrene-butadiene rubber, butyl rubber, etc. natural and synthetic rubbers, etc. Among these binder resins, preferred are styrene-acrylic resins, styrene-butadiene resins, and polyester resins.

The toner of the present invention can contain various additives as necessary. For example, physical property improvers include silicone oil, low molecular weight polyethylene,
Examples include low molecular weight polypropylene.

To produce the toner of the present invention, the electron-accepting substance, the binder resin, and carbon black are melted, kneaded, and kneaded using a heating roll or the like to make the resins and the like mutually compatible. It is possible to obtain a toner having an average particle size of 5 to 30 μm by dissolving, cooling and solidifying, and then pulverizing and classifying. Furthermore, the method for producing the toner of the present invention includes a suspension polymerization granulation method in addition to the pulverization granulation method. That is, a composition in which carbon black and an electron-accepting substance are mixed in a resin monomer for a binder is mixed with a polymerization initiator (benzoyl peroxide) in an aqueous system in the presence of a dispersant (polyvinyl alcohol, dodecylbenzenesulfonic acid, etc.). , azobisisobutyronitrile, etc.), a spherical toner can be obtained by granulation polymerization. Furthermore, the electron-accepting substance may be added externally as described above.

The toner of the present invention produced in this way can be prepared using known carriers such as iron powder, ferrite powder, nickel powder, cobalt powder, iron powder whose surface is coated with resin, etc.
In combination with glass beads etc., it can be used as a two-component toner for electrophotographic electrostatic recording, electrostatic printing, etc.

The amount of compounding agents used to prepare the toner of the present invention varies depending on the purpose of use, the type of carrier, etc.
Appropriate ranges are 0.1 to 10 parts by weight of the electron-accepting substance used in the present invention and 1 to 40 parts by weight of carbon black to 100 parts by weight of the binder resin. To prepare a two-component developer using such a toner, the toner of the present invention is usually mixed in an amount of 10 parts by weight to 100 parts by weight of the carrier.

According to the present invention, the amount of electrical charge shows a constant value even in a toner that is used repeatedly many times, and an extremely clear image can be obtained after development and transfer. In addition, the electron-accepting substance used in the present invention does not change its polarity even if the content in the toner changes slightly, and the manufacturing process is stable, resulting in a toner for developing electrostatic images with good yield. It is something that will be done. When it is contained in a two-component toner as in the present invention, the triboelectric properties of the toner particles are extremely stabilized, resulting in toner particles with a large amount of negative charge and high retention ability.

Examples of the present invention will be specifically described below.
This does not limit the embodiments of the present invention. In addition, all "parts" below represent "parts by weight."

Example 1 100 parts of a copolymer consisting of 65 parts of styrene and 35 parts of butyl methacrylate, 10 parts of carbon black with a pH of 3.0 (MOGULL, manufactured by Cabot), and p-benzoquinone (Ea = 2.02) as an electron-accepting substance. eV)
After mixing the two parts and ball milling for about 24 hours,
The mixture was kneaded using a hot roll, cooled, and then crushed and classified to produce a negatively chargeable toner having an average particle size of about 10 μm. A developer was prepared by mixing 2 parts of this toner with 100 parts of a spherical iron powder carrier (DSP135C manufactured by Dowa Iron Powder Co., Ltd.) having an average particle diameter of 100 μm. Next, a positive electrostatic latent image is formed using U-Bix3000, and this is powder developed using the developer to create a toner image, which is then transferred onto transfer paper using a positive transfer electrode. It was transferred and fixed by heating.

As a result, the obtained images were clear and free from development fog, and there was no problem in image quality.
Further, Table 1 shows the results of 20,000 copies of transferred images that were continuously formed using this developer.
In the first vote, the blank paper density (fog) is less than 0.02...○ 0.02 to 0.06...△ More than 0.06...× It is expressed in three stages, and the image quality is determined by visual inspection: There is no such thing...○ That It is expressed in a three-step system as shown in the following: . . . A little bit of .

Example 2 Example 1 except that 2.5-dichloro-p-benzoquinone (Ea = 2.41 eV) was used as the electron-accepting substance added to the toner.
A two-component developer was prepared in exactly the same manner as described above, and images were formed and copied 20,000 times. The results are shown in Table 1.

Example 3 A two-component developer was prepared in exactly the same manner as in Example 1, except that chloranil (Ea = 2.59 eV) was used as the electron-accepting substance,
Image formation was performed and copies were made 20,000 times. The results are shown in Table 1.

Example 4 In Example 1, 2.3 as the electron-accepting substance
A two-component developer was prepared in exactly the same manner as in Example 1, except that -dicyano-5,6-dichloro-p-benzoquinone (Ea = 2.99 eV) was used, and images were formed and 20,000 copies were made. . The result is the first
Shown in the table.

Comparative Example 1 A two-component developer was prepared in exactly the same manner as in Example 1, except that phthalamide (Ea = 1.50 eV) was used as the electron-accepting substance, and image formation was performed at 20,000 yen. I made multiple copies.
The results are shown in Table 1.

Comparative Example 2 PH as carbon black in Example 1
A two-component developer was prepared in exactly the same manner as in Example 1, except that MONARCH 880 (manufactured by Cabot Corporation) of 8.0 was used, and images were formed and copied 20,000 times. The results are shown in Table 1.

Comparative Example 3 PH as carbon black in Example 1
A two-component developer was prepared in exactly the same manner as in Example 1, except that 5.5 RAVEN 1800 (manufactured by Columbia) was used, and images were formed and copied 20,000 times. The results are shown in Table 1.

■■■ Tortoise Shell [0034] ■■■ As is clear from Table 1, in Examples 1 to 4, Q/M did not change much even after copying was performed 20,000 times, and the obtained images showed no development fog. The image was clear and clear, and there were no problems with the image quality. Further, no contamination inside the machine due to toner scattering was observed, and there was no deterioration in the durability of the toner.

On the other hand, in Comparative Examples 1 to 3, development fog occurred and the image quality was extremely noticeable. Toner scattering was also observed.

Claims (1)

[Claims] 1. An electron-accepting substance selected from anils and quinones whose electron affinity value exceeds the Ea value of I ₂ measured from the dipole efficiency of I ₂ /benzene system is added in an amount of 0.1 to 10% by weight based on the binder resin. % of carbon black having a pH of less than 5.0, in an amount of 1 to 40% by weight based on the binder resin.