JPH04260061A - Method for recording image - Google Patents

Abstract

PURPOSE:To offer an image recording method that fogging is prevented from being generated and a high-quality image whose density and resolution re excellent can be obtained. CONSTITUTION:As for the image recording method that an electrostatic charge image is formed on a carrier consisting of an organic photoconductive material having a negative electrostatic charge characteristic and the image is formed by sticking non-magnetic and one-component toner, which is carried through a developing roll formed cylindrical of an electorical conductive material, on the non-image part of the carrier, the non-magnetic and one-component toner obtained by adding the fluidization agent whose frictional electrification amount is -10 to -100muc/g by 0.01 to 1.5 pts.wt. is used.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to forming an electrostatic charge image on a carrier by means of electrophotography, electrostatic printing, etc. The present invention relates to an image recording method using so-called reversal development in which an image is formed by depositing toner.

0002

[Prior Art] Conventionally, in electrophotography, electrostatic printing, etc., an electrostatic charge image is formed on the surface of a photoreceptor by various means, and this electrostatic charge image is developed with toner to produce a visible toner image. Usually, this toner image is transferred to plain paper or the like and then fixed to obtain a final image.

[0003] Next, a general method for developing an electrostatic image is a magnetic brush method. In this magnetic brush method, a carrier such as iron powder or ferrite powder and a toner mainly composed of a resin and a colorant are used. Conventionally, a method using a two-component developer which is a powder mixture of However, when using the above two-component developer, the mixing ratio of toner and carrier (toner concentration)
Since the image quality will not be stable unless strictly controlled, a means of controlling the toner concentration is required, and there are also drawbacks such as the surface of the carrier becoming contaminated with toner during long-term use and the triboelectric charging ability of the carrier being reduced. .

[0004] In order to eliminate these drawbacks, a one-component developing method using a magnetic toner mainly composed of resin and magnetic powder has been developed and put into practical use. In this one-component development method, insulating magnetic toner is often used to obtain good transferability (for example, as disclosed in Japanese Patent Laid-Open No. 53-3
(See Publication No. 1136). Also, various methods have been proposed for developing methods, but a method in which toner is triboelectrically charged by friction between toners or friction between toner and a sleeve or the like is often used.

However, the developing method that utilizes toner triboelectric charging has the drawback that the toner tends to aggregate and the image quality tends to change depending on environmental conditions. Furthermore, since the magnetic toner contains about 20 to 70% by weight of magnetic powder such as magnetite, it has a drawback that its fixing properties are inferior to those of the two-component developer.

[0006] As a solution to the above-mentioned drawbacks,
Image recording methods using only non-magnetic one-component toner have also appeared.

FIG. 1 is an explanatory diagram of the main parts of an example of a developing device using non-magnetic one-component toner. In Figure 1,
1 is a developing roll, which is formed into a cylindrical shape from a non-magnetic metal material such as aluminum or stainless steel;
It is rotatably provided at the lower part of the toner tank 3 that accommodates the toner 2 . 4 is a blade made of flexible material;
It is fixed to the toner tank 3 and disposed such that its free end is in surface contact with the surface of the developing roll 1 and slidably engaged therewith. A bias voltage source 5 is connected to the developing roll 1, and the developing roll 1 is disposed facing a photoreceptor 6, which is made of an organic photoconductive material having a negative charge polarity and carries an electrostatic image, with a slight distance therebetween. Arrows indicate developing roll 1 and photoreceptor 6
indicates the direction of rotation.

With the above configuration, when the developing roll 1 is rotated in the direction of the arrow, the toner 2 in the toner tank 3 is charged to a negative polarity by the blade 4, and a thin layer is formed on the surface of the developing roll 1 by electrostatic force. The electrostatic charge image (not shown) formed on the surface of the photoreceptor 6 is transferred to the photoconductor 6, and a bias voltage lower than the potential of the electrostatic charge image is applied to the developing roll 1. It adheres to the non-image areas of (1) and can perform so-called reversal development.

[0009]

[Problems to be Solved by the Invention] In the conventional non-magnetic one-component developing device described above, the developing toner is made by adding a small amount of hydrophobic silica to the surface of toner particles mainly consisting of a binding resin and a colorant. Generally, a toner having a negative charge polarity is used. In this case, hydrophobic silica is added as a fluidity modifier or fluidizing agent for toner particles.

However, since the hydrophobic silica used as the fluidizing agent has a inherently large amount of triboelectric charge (-300 to -1000 μc/g), toners containing hydrophobic silica as a fluidizing agent When used, there is a problem that strongly negatively charged toner or positively charged toner adheres to the unexposed portions of the electrostatic image, which tends to cause background fog and deteriorate image quality.

[0011] The present invention solves the problems existing in the above-mentioned prior art, and provides an image recording method that can prevent the occurrence of background fog and obtain high-quality images with excellent image density and resolution. With the goal.

0012

[Means for Solving the Problems] In order to achieve the above object, in the present invention, an electrostatic charge image is formed on a carrier made of an organic photoconductive material having negative charging characteristics, and In an image recording method in which an image is formed by attaching non-magnetic one-component toner conveyed via a cylindrical developing roll made of a conductive material to an image area, the amount of triboelectric charge is -10 to -100 μc. /g of superplasticizer to 0.0
A technical measure was adopted in which a non-magnetic one-component toner containing 1 to 1.5 parts by weight was used. As such a fluidizing agent, for example, Al2 O3 (alumina)
, TiO2 (titanium oxide) can be used.

In the present invention, if the amount of triboelectric charge of the fluidizing agent exceeds -100 .mu.c/g, it is disadvantageous because background fog occurs and the image quality deteriorates. In addition, the amount of triboelectric charge mentioned above is −
If it is less than 10 μc/g, the toner and the fluidizing agent will separate and a sufficient fluidizing effect will not be obtained, which is not preferable.

Next, if the amount of the fluidizing agent added is less than 0.01 part by weight, the effect of modifying the fluidity of the toner is still insufficient, while if it exceeds 1.5 parts by weight, the amount of triboelectrification of the toner will decrease. This is undesirable because it becomes large and causes ground fog.

[0015] Examples of the binding resin to be contained in the toner used in the present invention include polystyrene, styrene/butadiene copolymer, styrene/acrylic ester copolymer, styrene/methacrylic ester copolymer, and the like. Known toner resins such as styrene resins, epoxy resins, and polyester resins can be used alone or in combination.

[0016] As the coloring agent, carbon black,
Known pigments or dyes such as chrome yellow, Hansa yellow, benzidine yellow, rose red red, aniline red, phthalocyanine blue, aniline blue, nigrosine dye, and aniline black can be used. Note that the content is preferably 3 to 10% by weight.

[0017] The toner used in the present invention may contain other additives such as a charge control agent, a mold release agent, and a filler in addition to the above-mentioned binder resin and colorant. Charge control agents include nigrosine dyes, reaction products of nigrosine dyes and carboxyl group-containing resins, triphenylmethane dyes, metal-containing (Cr) azo dyes, etc. Release agents include polypropylene, polyethylene, paraffin wax, carnauba. Examples of the wax, amide wax, etc., and fillers include inorganic fine powders such as calcium carbonate, talc, and clay. The contents of the above additives are appropriately selected depending on the properties required of the toner, but generally the charge control agent is 1 to 5% by weight, the release agent is 1 to 5% by weight, and the filler is 1 to 5% by weight. It is usually 10% by weight.

The toner used in the present invention can be manufactured by known means such as a pulverization method and a spray drying method. When using the pulverization method, the raw materials are premixed using a ball mill, dry mixer, etc., and then mixed with a kneader,
It is obtained by heating and kneading with a roll or the like, cooling and solidifying, pulverizing with a jet mill or the like, and then classifying. Note that the average particle diameter of the toner is preferably in the range of 5 to 20 μm from the viewpoint of image quality.

[0019]

[Function] With the above configuration, it is possible to appropriately set the amount of triboelectric charge of the toner while ensuring the predetermined action of the fluidizing agent, and it is possible to form a high-quality image without background fog.

[0020]

[Example] First, 77 parts by weight of styrene-acrylic copolymer (Himer SBM600 manufactured by Sanyo Chemical), 10 parts by weight of carbon black (#50 manufactured by Mitsubishi Chemical), and low molecular weight polypropylene (Viscol 550P manufactured by Sanyo Chemical)
), 2 parts by weight of a charge control agent (Bontron E81 manufactured by Orient Chemical Co., Ltd.), and 8 parts by weight of CaCO3 (NS#2500 manufactured by Nitto Funka Kogyo Co., Ltd.) were dry mixed, heated and mixed in a kneader, cooled and solidified, and then mixed in a jet mill. It was crushed and classified to produce a toner having a particle size of 5 to 25 μm. This toner contains Al2 O3, TiO2 and S.
iO2 (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) was externally added in the amounts shown in Table 1 to prepare a non-magnetic one-component developer.

[0021] Carriers for these external additives (manufactured by Hitachi Metals)
KBN100 ferrite carrier, 74-149μm
) against the blow-off method (Toshiba Chemical TB-
200 model)), the amount of triboelectrification is determined by adjusting the external additive concentration to 2.
When set to 0% by weight, Al2O3 is -50μc/g
, TiO2 -80μc/g, SiO2 -400
It was μc/g. In addition, the amount of triboelectric charge in Table 1 is calculated using the same ferrite carrier and a toner concentration of 5.0% by weight.
Shows the value when .

[0022]

[Table 1]

Using the non-magnetic one-component developer described above and using the developing device shown in FIG.
Electrostatic charge image (surface potential -
550 V, residual potential -80 V), and the resulting visible image was transferred onto plain paper, followed by heat roll fixing (fixing temperature 165°C, fixing pressure 1 kg/cm2), and the resulting image was evaluated. The results are also listed in Table 1.

In the above development, the photoreceptor 6 shown in FIG. 1 is rotated at a circumferential speed of 50 mm/sec, and the developing roll 1 is rotated at a circumferential speed of 125 mm/sec. The thickness of the film was set to 0.1 mm, and contact development was performed. Further, a bias voltage of -450 V DC was applied to the developing roll 1.

As is clear from Table 1, first, No. In No. 3, the amount of triboelectric charge was too large, so fogging was observed. This is due to the fact that SiO2 has a large inherent triboelectric charge as described above. On the other hand, N
o. 1 and no. In No. 2, a high-quality image without fogging was obtained.

Next, the influence of the amount of fluidizing agent added will be described. First, No. 1 with no Al2 O3 added. In No. 4, the fluidity was poor, the transportability on the developing roll 1 was reduced, and uneven development occurred. Further, the image density remained at 1.20, which was a level that was problematic for practical use. On the other hand, Al2
No. 2 with 2.0% by weight of O3 added. In 11,
A phenomenon was observed in which background fog occurred and excessive Al2O3 was scattered from the developing roll 1, contaminating the inside of the developing device. On the other hand, No. 4~No. In No. 10, a good image was obtained without fogging.

[0027]

[Effects of the Invention] Since the present invention has the structure and operation as described above, it is possible to prevent the occurrence of fog while ensuring the predetermined action of the fluidizing agent, and to produce high-quality images with excellent image density and resolution. It has the effect of being able to obtain

[Brief explanation of the drawing]

FIG. 1 is an explanatory view of the main parts of an example of a developing device that uses non-magnetic one-component toner.

[Explanation of symbols]

1 Developing roll 2 Toner

Claims (1)

[Claims] 1. An electrostatic charge image is formed on a carrier made of an organic photoconductive material having negative charging characteristics, and a developing roll formed in a cylindrical shape made of a conductive material is placed in a non-image area of the carrier. In an image recording method in which an image is formed by adhering non-magnetic one-component toner conveyed through
．． An image recording method characterized by using a non-magnetic one-component toner containing 5 parts by weight.