JPH0810351B2 - Electrophotographic developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention is a development in which a toner and a carrier are combined for developing an electrostatic charge image formed in an electrophotographic method, an electrostatic printing method, an electrostatic recording method or the like. Regarding agents.

<Prior Art><Problems to be Solved by the Invention> The developer for dry electrophotography is a mixture of a carrier and a toner, and the toner has an appropriate specific charge due to frictional charging with the carrier, and the toner is applied to the surface of the carrier by electrostatic force. It is attached. The charge polarity and charge amount level of the toner are determined by the material relationship on the triboelectric charge series between the carrier and the toner. In the development process, a photoconductive phenomenon is used to form an electrostatic latent image on a photoconductor, and charged toner in the developer is attached to the electrostatic latent image by a magnetic brush of a carrier to form a visible image. Is a process.

In the existing toner, a styrene-acrylic resin or a polyester resin, a colorant, and a charge control agent are blended, and the resin component is dispersed together with other blending agents by melt kneading and pulverizing, or by emulsion polymerization or suspension polymerization. It is a fine powder having an average particle diameter of 6 to 15 μm. It is difficult with the existing technology to disperse the above-mentioned compounding components in the small particles sufficiently uniformly so as to have the same ratio as the compounding ratio over the entire area of the particles. In particular, the charge control agent is sufficient if only a necessary amount is present on the surface of the particles, but in the present production method, the charge control agent is contained in the particles in an excessive amount in excess of the required amount. When the charge control agent is added in an excessive amount and the dispersion is poor in this way, the charge amount of the toner in the developer is low, a large amount of uncharged toner is present, and the charge amount distribution is wide. Therefore, an image formed by a developer using such a toner has a low density or fog, and it is difficult to obtain a stable toner.

The carrier is generally an iron powder carrier of about 30 to 200 μm,
Magnetic powder such as ferrite carrier, magnetite granulation carrier, resin carrier, etc. When making a coated carrier, the current technology is to coat the surface with a solution method to provide charge control and wear resistance improvement. However, the composition is not uniform and the film thickness is not uniform, and reproducibility is poor due to poor adhesion of the coating material. Further, in an image formed by a developer using such a carrier, density unevenness, uncharged toner, fogging, and the like, the sensitivity of the toner concentration sensor changes due to poor fluidity in the developing machine, and therefore the carrier There is a problem that the toner specific density is unstable.

The electrophotographic developer of the present invention is for solving the above problems, and it is an object of the present invention to provide an electrophotographic developer having an appropriate charge amount level and wear resistance by combining a toner and a carrier. It is intended.

<Means for Solving the Problems> The present invention is one in which a polymerized film is formed in advance by forming a plasma polymerized film on each powder surface of each of a toner and a carrier used for a developer for electrophotography and modified. Is.

Thus, both the toner and the carrier modified by forming the plasma-polymerized film can be mixed in a predetermined ratio to obtain a developer having a required charge amount.

In addition, "plasma polymerization" is a case where an organic gas is used as an introduction gas and is made into plasma while being sent to a reactor to form an organic polymer thin film.

 The present invention will be described in detail below.

Coating by plasma polymerization is carried out by a method in which a gaseous monomer is directly polymerized on the surface of a core material of powder of toner or carrier and resin coating is performed. As the polymerization device, for example, a bell jar type of internal electrode type, a cross type,
It is possible to apply by applying an external electrode type cylindrical device or the like.

FIG. 1 is an example of a bell jar type plasma polymerization apparatus. As a reactor of the plasma polymerization device, a vibrating plate provided on the electrode below the upper and lower two parallel plate electrodes 12 in the bell jar 11.
13 Place the toner or carrier powder on top of the
After the inside of 11 is evacuated by the vacuum pump 15, the bell jar is
A proper amount of a gaseous monomer gas is flown into the inside of the gas 11 through the gas introduction pipe 14, and the vibration is transmitted to the powder of the toner or the carrier as the core material by the vibrating plate 13. This vibrating operation causes the powder in the vibrating dish 13 to begin to fluidize. Next, high-frequency power is supplied to the upper and lower parallel plate electrodes 12 to generate plasma, and the monomers are polymerized in the bell jar 11. At this time, the powder is constantly fluidized and tumbled by vibration while coating the polymerized film, so that the polymerization uniformly proceeds on the surface of the core material and the plasma polymerized film is uniformly coated. The monomer is not limited to a gaseous monomer at room temperature and atmospheric pressure, but may be a liquid monomer. When liquid monomer is used as a raw material, it is practically useful in terms of cylinder, piping, and price.
The raw material container containing the liquid is heated from the outside, vaporized and introduced into the reactor through a pipe.

The film forming rate on the powder surface varies depending on the plasma operating conditions such as the degree of vacuum, the applied voltage, the distance between the electrodes, the substrate temperature, the type of monomer, the flow rate and the flow pattern in the polymerization apparatus. It is necessary to find the optimum conditions for the film formation structure and the film formation rate formed on the powder surface in a timely manner according to various monomers.

Generally, carriers of iron powder or ferrite have low surface energy, poor compatibility with resin, and weak adhesion even if wet coating can be performed, so cracking and cracking will occur if stirring is strong in the developing device. However, according to the present invention, the adhesion between the plasma-coated powder and the polymer is improved and improved, and the life as a carrier is extended.

As raw material monomers used in the present invention, tetrafluoroethylene, heterofluorobenzene, perfluorobenzene, pentafluorobenzene, perfluoropyridine, perfluoromethylcyclohexane, hexafluoropropene, hexamethyldisiloxane, triethoxyvinylsilane, diallyldimethylsilane. , Methane, ethane, propane, n-butane, i-butane, propylene, acrylonitrile, propionitrile, propylamine, arylamine, ethylene, allene, acetylene, ethylene oxide, benzene, toluene, xylene, hexane, cyclohexane, acrylic acid, Examples include but are not limited to methacrylic acid, chlorobenzene, nitrotoluene, styrene and derivatives.

In the present invention, argon, hydrogen, nitrogen, air or the like can be used as an entrained gas used in plasma polymerization.

<Operation> In the toner and carrier constituting the electrophotographic developer according to the present invention, a thin film of a polymer substance having chargeability or abrasion resistance is formed on the powder surface of the toner and carrier by plasma polymerization. . Therefore, even if the toner of the core material does not contain the charge control agent or does not have the charging function, the triboelectric charging function is exhibited by the plasma polymerization.

Further, the carrier not only has improved charge controllability, but also has a stronger adhesive force than the coating by the solution method, so that it can withstand agitation in the developing device.

Therefore, if a developer in which the toner and the carrier that are appropriately plasma-polymerized are combined is manufactured, it can be adjusted to an arbitrary charge amount level, and the developer can be stabilized and the image can be stabilized.

Depending on the composition of the plasma polymerized film applied to the surface of the toner, the charge control agent may not be mixed in the core of the toner, and the carrier may have a sufficient function as a developer without the plasma polymerized film. Is also possible.

<Example> Next, the present invention will be described with reference to an example. The following parts indicate weight ratios.

Example 1 50 g of a carrier (Dowa iron powder non-coated ferrite carrier F-100) was placed on a vibrating dish in a plasma polymerization apparatus,
It was evacuated with a vacuum pump, vibrated and stirred. Tetrafluoroethylene was introduced from the gas introduction part, the degree of vacuum in the reactor was maintained at 0.1 Torr, and a high frequency power supply was turned on to perform glow discharge. After glow discharge for 2 hours, a uniform polymer film was formed on the powder surface.

Repeat the above operation 5 times to get 25 coated carriers.
I made 0g.

On the other hand, toner has a compounding ratio 11 μm toner was prepared by kneading and pulverizing. 20 g of this toner was placed on a vibrating dish, hexamethyldisiloxane as a raw material monomer was introduced into a bell jar, and glow discharge was performed for 1 hour to coat the powder surface. Other operations were performed in the same manner as in the case of the carrier.

As described above, 235.5 g and 12.5 g of the toner and the plasma-coated carrier were respectively taken and uniformly mixed to obtain a developer having a toner concentration of 5%.

The charge rising characteristics of the obtained developer were measured by the magnet blow-off method (see JP-A-57-186176). The polarity of the toner obtained here was positive. Further, as compared with Comparative Examples 1 to 5 described later, a clear difference in charging characteristics was observed between the toner and carrier with and without plasma coating, and the developer of the combination of toner and carrier with plasma coating was observed. Was the desired charge level.

Further, when an image was printed using a copying machine, a clear image was obtained without a low image density, uneven density, or fogging, and there was no deterioration of the carrier. (See FIG. 2) Example 2 50 g of a carrier (the same as in Example 1) was placed on a plate on a vibrating substrate in a plasma polymerization apparatus, and exhausted to 10 ⁻⁵ Torr with a vacuum pump as in Example 1. did. Hexamethyldisiloxane was introduced into the polymerization apparatus as a coating material, glow discharge was again generated under a pressure condition of 1 Torr, the vibrating substrate was operated, and polymerization was carried out for about 1 hour. The above operation was repeated 5 times to prepare 250 g of a coated carrier.

As the toner, the same plasma uncoated product as in Example 1 was used,
Tetrafluoroethylene as a monomer raw material was introduced into a bell jar, and glow discharge was performed for 1 hour to coat the toner surface. Other operating conditions are the same as the carrier.

A developer was prepared using the toner and carrier obtained as described above, and the charging characteristics were measured. The charging polarity of the obtained toner was negative. As is clear from Comparative Examples 1 to 5, the difference in charging characteristics between the plasma-uncoated products is large.

Further, it was confirmed that a clear image was obtained by displaying an image. (See FIG. 2) <Comparative Example 1> The carrier is plasma-coated with the same tetrafluoroethylene as in Example 1, and the toner is a powder obtained by a kneading / pulverization method in which no polymer coating by plasma polymerization is applied (Example 1). The same powder) was used to make a developer having a toner concentration of 5%. Although the toner had a positive polarity, the charge amount level was low, the image surface was fogged, and the toner was often scattered from the developing machine. (See FIG. 2) <Comparative Example 2> The same hexamethyldisiloxane as in Example 2 was plasma-coated as a carrier, and the toner was the same non-coated product as in Comparative Example 1. This carrier toner was combined to form a developer having a toner concentration of 5%. Although the polarity of the obtained toner was negative, the charge amount level was low, the image was fogged, and the scattering was large. (See FIG. 2) <Comparative Example 3> The carrier used was the same non-coated ferrite as that shown in Example 1, and the toner was the same plasma-coated tetrafluoroethylene as in Example 2, and the toner concentration was 5%. I made a developer. The toner polarity of this developer was negative, and the image was fogged and not clear. (See FIG. 2) <Comparative Example 4> The same non-coated ferrite as in Comparative Example 3 was used as the carrier, and the hexamethyldisiloxane of Example 1 was plasma-coated as the toner to prepare a developer having a toner concentration of 5%. It was The toner polarity was positive, but the charge level was too low and fogging and scattering occurred. (See FIG. 2) <Comparative Example 5> The same non-coated ferrite as in Comparative Example 3 was used as the carrier, and the same non-coated product as in Comparative Example 1 was used as the toner to prepare a developer having a toner concentration of 5%. The charge level is low,
No clear image was obtained. (See FIG. 2) According to FIG. 2, in the range of stirring rotation speed 20 or less, Example 1 has a large charge amount of +5 to 9 and Example 2 has a small charge amount of −4 to −10. This is completely different from those having a charge amount near 0 in Comparative Examples 1 to 5.

<Effects of the Invention> The present invention forms a thin film of a polymer substance by preliminarily performing plasma polymerization on the powder surfaces of toner and carrier,
It is possible to obtain an electrophotographic developer comprising a carrier in which the charge amount level of the developer obtained by combining the toner and the carrier can be appropriately adjusted and which can withstand a strong stirring force.

[Brief description of drawings]

FIG. 1 is a schematic view of a bell jar type plasma polymerization apparatus used in the present invention. FIG. 2 is a graph showing the relationship between the number of revolutions of stirring and revolution of the mixture of toner and carrier and the amount of charge per unit weight in the developers of this example and comparative examples. 11 ... Bell jar 12 ... Plate electrode 13 ... Vibration plate 14 ... Gas inlet tube 15 ... Vacuum pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 9/10 351 (72) Inventor Shigeo Matsuyama No. 3 Soba-cho, Shizuoka-shi, Shizuoka Company Tomoegawa Paper Mill Technical Research Institute (72) Inventor Akihiro Sano No. 3 Somune-cho, Shizuoka City, Shizuoka Prefecture Tomoegawa Paper Mill Technical Research Institute (72) Inventor Shigeru Ebioka Shizuoka-shi Somune-cho, Shizuoka Prefecture No. 3 No. 1 at Tagawagawa Paper Research Laboratory (56) Reference JP 62-8169 (JP, A) JP 62-257175 (JP, A) JP 62-14167 (JP, A)

Claims (2)

[Claims] 1. A toner powder and a carrier powder constituting a core material are formed by plasma polymerization to form a polymerized film, and are blended in combination so as to maintain a desired charge amount. Electrophotographic developer. 2. The electrophotographic developer according to claim 1, wherein the toner constituting the core material is made by a kneading pulverization method or a polymerization method.