JPS60151653A - Positively triboelectrifiable developer - Google Patents

Abstract

PURPOSE:To reduce fog by mixing an insulating magnetic powder contg. magnetic powder in a resin with an insulating magnetic powder contg. the magnetic powder in a resin and a butadiene-acrylic-styrene resin obtained by copolymerizing nigrosine. CONSTITUTION:A positively triboelectrifiable developer is prepared by mixing the first insulating magnetic material contg. 50-80wt% magnetic powder in a resin with the second insulating magnetic material contg. 5-50wt% magnetic powder in a resin and 0.1-40, preferably, 5-15wt% butadiene-acrylic-styrene resin contg. copolymer component units of nigrosine. This nigrosine copolymer resin has good compatibility with styrene, acrylic, epoxy, and polyester resins, and in every small part of this resin mixture nigrosine is uniformly contained and distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a positively charged developer that enables electrostatic transfer in an electrostatic copying machine using an organic photoconductor as an example of a photoreceptor film. It is something.

Conventional configurations and their problems In recent years, electrostatic copying machines have been using organic semiconductor coatings for their photoreceptor films. Taking advantage of its flexibility, the photoreceptor film has been made into a belt shape in order to reduce the size of the photoreceptor film, or to reduce the cost. Plans have been made and implemented to reduce the cost by replacing high-temperature selenium films.

The charging polarity of the latent image on the photoreceptor film of the organic photoconductor exhibits normal charging.

Generally, in order to impart a positive charge to a developer, a positive charge control agent is mechanically dispersed in a styrene resin, styrene-acrylic resin, epoxy resin, etc. when nigrosine is added to the toner and carrier of the developer. In addition, magnetic powder, pigments, wax, etc. were added and mixed in, and the particles were ground to the desired particle size. However, with the above configuration, sufficiently uniform dispersion cannot be obtained. This is because the particle size of nigrosine powder is as large as 3 to 50 μm, while the average particle size of toner is 10 to 15 μm. With 7L, there is a high possibility that particles of nigrosine itself will be formed, but not only does nigrosine not wet well with the resin, it is not compatible with the resin itself, so physical mixing using conventional methods results in poor dispersion. Nigrosine is often exposed on the surface. These phenomena also apply to stearic acid derivatives and oleic acid derivatives of nigrosine.

The developer is charged on the surface of the carrier sleeve, the blade, the electrostatic holder, and each toner with which the toner comes into contact. Each toner particle is charged by frictional charging between these particles and the toner, but if the polarities are aligned or the amount of charge is above the appropriate range, or if the polarities are insufficiently aligned, fogging and reversed images may occur. It will be done. Therefore, in a toner containing nigrosine having a large particle size, part or all of the surface is exposed, and due to friction, which is a charging mechanism, nigrosine is increasingly broken down and pulverized, thereby changing the charging distribution.

When Tsumasinigrosine and iron powder are strongly rubbed and collided, nigrosine disintegrates, becomes fine powder, and becomes a highly charged powder.
It is thought that the fogging phenomenon increases because the charge distribution is higher than the original charge distribution and is far different from the normal charge distribution of toner.

OBJECTS OF THE INVENTION The purpose of the present invention is to provide a stable positively charged developer in which nigrosine does not disintegrate or deteriorate with a little shaking, causes extremely little fogging, and maintains images even after a large number of copies are made. That's true.

Structure of the Invention The positively charged developer of the present invention comprises a first insulating magnetic powder containing 50 to 80 weight percent of a magnetic material in a resin on one side, and a first insulating magnetic powder containing 5 to 50 weight percent of a magnetic material in a resin on the other hand. A second resin containing 0.1 to 40 weight percent (preferably 5 to 15 weight percent) of a butadiene-acrylic-styrene resin copolymerized with nigrosine.
This is a positively charged developer composed of a mixture of insulating magnetic powder and insulating magnetic powder.

As a result, the mixture of the first insulating magnetic powder serving as the carrier and the second insulating magnetic powder serving as the toner, ie, the developer, becomes what is called a pseudo two-component toner.

Instead of containing general nigrosine coarse powder in this second insulating magnetic powder, by adding butadiene-acrylic-styrene resin copolymerized with nigrosine, nigrosine is molecularized and butadiene- It is integrated with the acrylic-styrene resin through chemical bonds, and the entire resin is finely dotted with nigrosine molecules, resulting in uniform ideal dispersion. The nigrosine co-polymerized resin has good compatibility with styrene resin, acrylic resin, epoxy resin, and polyester resin, which are generally used as the basic resin of toner.
The mixed resin contains nigrosine evenly distributed in any minute portion. The toner created by adding a magnetic material to the mixed resin configured in this way, heating, kneading, and pulverizing it causes frictional electrification, so it is used as a carrier.

Even if the nigrosine itself collapses and becomes pulverized due to collisions and friction between the sleeve, grade, the surface of the electrostatic holder, and each toner, charge fluctuations due to the pulverization are extremely small. Instead of using a hard substance such as iron powder as a carrier, the first insulating magnetic powder (as described in the claims) having 50 to 80 weight percent of magnetic material in the resin is used as the carrier. Among the structure of the pseudo two-component developer and the cage means, toner particles are extremely less likely to collapse or become pulverized due to friction and collision with the carrier, and as a result, a stable charge amount and charge distribution are obtained, resulting in a long period of fogging and image density reduction. It was found that very few results were obtained in the time copy repetition test.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described. As the butadiene-acrylic-styrene resin in which nigrosine was copolymerized in the examples, Bontron OR'-57 (manufactured by Orient Kagaku ■) was used.

Example 1 (Hereinafter, the unit is weight percent) [I]
Tona compounded styrene-acrylic resin (MDS687) 62 (MD8
687 is manufactured by Sekisui Kagaku ■) Magnetic material (Magnetite EPT-500) 25 (EP
T-500 is manufactured by Toda Kogyo ■) Charge control agent (Bontron 0R-57) 10 (Bontron 0R-67 is manufactured by Orient Chemical ■) Wax (Viscol 550F N 3 (Viscol 650P is manufactured by Sanyo Chemical ■) Each of the above raw materials After putting it into a Henschel mixer and pre-stirring for a time not exceeding 45°C, then heating and melt-kneading it in a twin-screw extruder,
The powder was pulverized using a jet mill and classified using a classifier to obtain toner powder having a target average particle size of 12 μm.

[■] Carrier blended styrene-acrylic resin (MDS687) 25 Magnetic material (Magnetite EPT-600) 75 In the same way as the toner manufacturing method, each raw material was placed in a Henschel mixer and premixed for a time not exceeding 45°C, and then After heating, melting and kneading with a shaft extruder, the mixture was pulverized with a jet mill and classified with a classifier to obtain the desired carrier powder with an average particle size of 30 μm.

Weigh toner powder and carrier powder at a ratio of 3nia (weight ratio), and add colloidal silica (Aerosil RA200) to it.
H: Nippon Aerosil ■) was added to the weighed mixture at a rate of 0.
5% by weight was added and forcibly stirred three times for 10 seconds using a mixer to obtain a pseudo two-component positively charged developer.

[I] Toner-blended styrene resin (Picolastic D150) 60 (Picolastic]: H50 manufactured by Esso Standard Oil ■) Magnetic material (Magnetite PP-7) 25 (PP-y manufactured by Kanto Denka Kogyo ■) Charge control agent (Bontron 0R-57) 1-2 Wax (Viscol 55qP) 3 Using the same manufacturing method as Example 1, the average particle size was 11μ? A toner powder of W was obtained.

[■] Carrier-containing styrene resin (Picolastic D150) 30 Magnetic material (Magnetite PP-7) 70 A carrier powder having an average particle size of 29 μmm was obtained by the same manufacturing method as in Example 1. Similarly, toner powder and carrier powder were mixed in the same manner as in Example 1 to obtain a positively charged developer.

Example 3 [-■] Toner blended polyester resin (ATR2010) 62 (AT-R
2o1o is made by Kao Soap ■) Magnetic material (Magnetite EPT-500) 25 Charge control agent (Bontron 0R-57) 10 Wax (Viscol 56oP) 3 Toner powder with an average particle size of 12 μm was produced using the same manufacturing method as in Example 1. Obtained.

(II) Carrier-blended polyester resin (ATR2010) 23 Magnetic material (Magnetite EPI4'-500) 771 A carrier powder with an average particle size of 35 μm was obtained by the same manufacturing method as in Example 1. In addition, toner powder and carrier powder A positively charged developer was obtained using the manufacturing method of Example 1.

Example 4 [I] Toner compounded epoxy resin (Epicor 1004) 65 (Epicor) 1004 is manufactured by Shell Oil ■) Magnetic material (magnetite
PP-7) 22 charge control agent (Bontron OR-67)
1° Wax (Viscol 550P) 3 A toner powder having an average particle size of 1 μηl was obtained by the same manufacturing method as in Example 1.

[■] Carrier-blended epoxy resin (Epikoat 1004) 4° magnetic material (Magnetai) EPT-500) e.

A carrier resin having an average particle size of 13 μm was obtained by the same manufacturing method as in Example 1. Similarly, toner powder and carrier powder were mixed in the same manner as in Example 1 to obtain a positively charged developer.

Comparative Example 1 [I] Toner compounded styrene-acrylic resin (MDS687) 70 magnetic material (
Magnetite EPT-500) 25 Charge control agent (Bontron N01) 2 (Bontron NO1 is manufactured by Orient Chemical ■ and has a particle size of 1Q to 20 μm) Wax (Viscole 66 oP-) 3 Using the same manufacturing method as Example 1, the average particle size is 12 μm. Toner powder was obtained.

(ID carrier blended styrene-acrylic resin (MDS687) 75 magnetic material (
Magnetite EPT-500) 25 A carrier powder having an average particle size of 32 μm was obtained by the same manufacturing method as in Example 1. Similarly, toner powder and carrier powder were mixed in the same manner as in Example 1 to obtain a positively charged developer.

Comparative Example 2 The same toner formulation as Comparative Example 1 was prepared, and the average particle size of the carrier was 30 μm. I'L iron powder was used, and both were mixed in the same manner as in Example 1 to obtain a positively charged developer.

Effects of the Invention As mentioned above, nigrosine is not used alone, but is copolymerized with a butadiene-acrylic-styrene resin to fully satisfy the dispersibility and compatibility.
By combining the soft friction against the toner powder using R-57) and the colliding carrier powder, the fogging phenomenon 2 and the decrease in image density were significantly improved. Table 1 shows the results of long-term copying (running test) of 30,000 copies.

Table 1: Running test results *1 About the Capri phenomenon; This is a phenomenon in which toner powder scatters to unnecessary areas. If the number of toner particles existing in an area of 11R square is 6 or less, ○, 5 to 26, △, 26 The above was marked as ×.

*2 Regarding changes in charge amount: If the initial charge amount is within 10 to 20 μc/y in the blow-off charge measurement, and the value after the running test is within 10 to 20 μc/y compared to the initial value. , △ for 20-30μc/y, 30
It was marked as × if it was μc/y or more.

*3 Regarding decrease in image density; Image density (D measured by reflection densitometer) decreases by 5% or less from the initial value ○, 6 to 1
5% was rated △, and 15- or more was rated ×.

As can be seen from the results in Table 1, Examples 1 to 4 according to the present invention
However, in Comparative Example 1, in which nigrosine with a large particle size of 7 was simply mixed mechanically, a sufficiently satisfactory result could not be obtained even when the carrier was soft. It can be seen that when hard iron powder is used as a carrier, the toner deteriorates extremely. By chemically binding and dissolving nigrosine, which is a positive charge control agent of the present invention, friction,
Even if it is pulverized due to collision, the amount of charge is extremely high (p-ζ), and the soft carrier composition further prevents pulverization, thereby making it possible to obtain a stable positively charged developer.

Claims (1)

[Claims] (1) Co-polymerization of a first insulating magnetic powder containing 60 to 80 percent by weight of a magnetic material in a resin, and the other containing 5 to 50 percent by weight of a magnetic material in a resin and nigrosine. A positively charged developer characterized in that it is mixed with a second insulating magnetic powder containing 0.1 to 40 weight percent of a butadiene-acrylic-styrene resin.