JPS63200163A - Toner for development of electrostatic image - Google Patents

Abstract

PURPOSE:To obtain a picture image having high quality by incorporating at least a colorant, a charge regulating material and a compd. having a specified unit structure into a binder resin. CONSTITUTION:A colorant, a charge regulating material, and a compd. having a unit structure expressed by the formula I are incorporated into a binder resin. In the formula, R is an organo group; M is a metal; (m) is a valency of the metal. The M-O-B structure of this compd. is considered to have an important function as a positive charge regulating material. Accordingly, there is no restriction concerning the kind of the organo group bonding to the metal atom, but such group which serves to improve the affinity to the binder resin and increases the charge density of the metal atom is preferred. By this constitution, a positively charged toner capable of stabilizing the quantity of frictional electric charge and having a sharp and uniform distribution of frictional electric charge is obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. More specifically, it relates to a developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a positively charged toner that is uniformly and strongly positively charged, visualizes a negative electrostatic charge, and provides a high quality image in a photographic development method.

[Conventional technology]

Conventionally, as an electrophotographic method, U.S. Patent No. 2゜297.69
Specification No. 1, Japanese Patent Publication No. 42-23910 (U.S. Patent No. 3,666.383), Japanese Patent Publication No. 43-247
Publication No. 48 (U.S. Patent No. 4,071,361)
Many methods are known, such as, but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is transferred to developer powder (hereinafter referred to as toner). ), and after transferring the toner image to a transfer material such as paper as necessary, it is fixed by heat, pressure, a pressurized heat constant roller, solvent vapor, etc. to obtain a copy. In addition, if there is a step of transferring a toner image, usually
A step is provided to remove residual toner on the photoreceptor.

A developing method that visualizes an electrical latent image using toner is patented in the United States! The magnetic brush method described in No. 2.874.063-fir, the cascade development method described in No. 2.618,552, and No. 2,22.
The powder cloud method described in US Pat. No. 3,909,258 and the method using conductive magnetic toner are known.

As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Positive charge control agents used in such dry developing toners include, for example, generally quaternary and ammonium compounds and organic dyes, particularly basic dyes and their salts, and nigrosine base and nigrosine are often used as positive charge control agents. It is used as an agent.

These are usually added to a thermoplastic resin, dispersed in a heated melt, finely pulverized, and adjusted to an appropriate particle size as necessary before use.

However, these charge control agents tend to cause development in which charge controllability is deteriorated due to mechanical shock, friction, changes in temperature and humidity conditions, and the like.

Therefore, when a toner containing these as a charge control agent is used for development in a copying machine, the toner may deteriorate during durability as the number of copies increases.

Furthermore, since it is extremely difficult to uniformly disperse these charge control agents in a thermoplastic resin, there is a problem in that there is a difference in the amount of frictional charge between toner particles obtained by crushing them. There is. For this reason, various methods have been used to achieve more uniform dispersion. For example, basic nigrosine dyes are used by forming salts with higher fatty acids in order to improve their compatibility with thermoplastic resins, but unreacted fatty acids or salt dispersion products are often exposed on the toner surface. This contaminates the carrier or toner carrier, causing a decrease in the fluidity of the toner, fog, and a decrease in image density. Alternatively, in order to improve the dispersion of these charge control agents into the resin, a method has been adopted in which charge control agent powder and resin powder are mechanically pulverized and mixed beforehand and then hot melt kneaded. The reality is that poor dispersion cannot be avoided, and that sufficient uniformity of charge has not yet been achieved for practical use.

In addition, amino groups are introduced into the binder resin by copolymerization or graft polymerization with a positively chargeable polymer such as dimethylaminoethyl methacrylate, and by making the binder resin itself positively chargeable, the toner is uniformly distributed. Attempts have also been made to provide a similar charge. However, the positive chargeability of the binder resin as described above is not yet sufficiently stable, and the magnitude of the frictional force exerted between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves may vary. It is extremely difficult to always give a constant and stable positive charge to the toner because it varies greatly depending on the friction probability and the friction probability. Copied images obtained with toner having unstable positive chargeability and having only a low frictional charge amount are prone to fogging and scattering. On the other hand, if an excessive amount of triboelectrostatic charge is maintained, the image will be rough and only a low density image will be obtained.

Recently, as the demand for improved image quality has increased, image forming apparatuses such as electrophotographic printers that use digital image signals are being used. When using conventional positively chargeable toner, the non-uniformity of charge that tends to occur on the surface of toner particles between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves can be solved digitally. It has become clear that a particular problem arises when developing an electrostatic latent image formed using a static image signal, and a developer having a more uniform charge has been desired.

That is, when the image signal is a digital signal, the latent image is formed by a collection of dots with a constant potential, and solid areas, halftone areas, and light areas are each expressed by changing the density of the dots. Therefore, if any part is binary, it will basically be formed from an electrostatic latent image of approximately the same potential.

Furthermore, recently there has been a growing demand for improved image quality, and it has become necessary to improve gradation reproducibility by using a three-value or four-value multi-value dither method instead of the black-and-white binary dither method described above. This multi-level dithering method is useful when removing false contours that tend to occur in highlight areas, or when simultaneously reproducing an image containing a mixture of halftones and line images. This technology is also essential when reducing the size and improving resolution.

The concept of dither matrix in multilevel dither method is explained first.
This will be explained with reference to FIGS. (a) and (b). Figure 1 (
a) is a 2×2 ternary dither matrix, which includes areas St, 52 . S3 represents three density levels of white, gray, and black, respectively. In addition, FIG. 1(b) is a 2×2 four-value dither matrix, with areas St, S2°S
3. S4 represents four density levels of white, light gray, dark gray, and black, respectively.

The dot size is, for example, 16 dots/mm.

2(a), (b) and 3(a), (b) are exposure intensity distributions when performing ternary recording in an optical scanning type electrophotographic printer.

FIG. 3(a) and the corresponding potential distributions of the electrostatic latent image in FIG. 2(b) and FIG. 3(b) are shown. Second
The broken lines in Figures (a) and 3(a) represent the signal output for outputting a light beam to form a multivalued latent image, and Figure 2(a) shows the brightness that controls the laser output. Through modulation, the gray level corresponding to S2 in FIG. 1(a) (hereinafter referred to as M level) and the black level corresponding to 53 (hereinafter referred to as H level)
This is a method to obtain the level). For example, the M level can be obtained with a laser output that is 1/2 that of the H level.

′! Figure J3 (a) shows a method of obtaining the M level and H level by pulse width modulation that controls the laser output time.

This can be obtained, for example, by setting the pulse width of the M level to 1/2 that of the H level. Figure 2 (a) and Figure 3 (
The potential distribution of a latent image created by a light beam having the exposure intensity distribution shown in a) is as shown in FIGS. 2(b) and 3(b). The latent image contrast of the level tends to be smaller than that of the H level due to a decrease in the MTF of the latent image. Therefore, this M-level image density becomes almost the same gray as the image density after the M-level development shown in FIG. 2(b) by brightness modulation.

Figure 4 shows the development characteristics (Vs
-Dp characteristics), and Fig. 2(b) and Fig. 3(
In order to reproduce the M level and H level latent images (respective potential contrasts are represented by ■ and ■) in b), especially H
If the level cannot be set sufficiently high, a Vs-Dp characteristic (indicated by a solid line in the figure) with a relatively large gamma (inclination of image density with respect to latent image potential) is required. However, when conventional toners or developers for developing analog latent images are used, they often tend to exhibit development characteristics as shown by the solid line (3), which causes various problems. Further, when developing a latent image expressed by the density of digital dots, more precise control of this Vs-Dp convex curve is required than in a conventional analog latent image. One is that in order to develop a digital latent image, it is necessary to make the slope (gamma) of the Vs-Dp convex curve larger than before, and it is also necessary to control this slope so that it does not fluctuate.

A conventional charge control agent was used. The non-uniformity of charge generated in the toner becomes an obstacle to increasing the slope of the Vs-Dp convex curve, and also tends to cause a state of fluctuation. If the slope of the Vs-Dp convex curve is small, H level dots will not be reproduced at a sufficiently high density. Also, the density difference between the H level and the M level cannot be reproduced sufficiently, or the potential at the edge of the dot is lower than that at the center, as shown in Figure 20 and Figure 3.
This causes problems such as poor image sharpness at the edges of the dots, resulting in a defective image with low image density, lack of sharpness, and low resolution. Further, this non-uniformity of charge causes fluctuations in the Vs-09 curve when copying is repeated a large number of times or due to changes in the environment of use, resulting in the above-mentioned problems.

In addition, recently, OPC photoreceptors have been made more durable, and positively chargeable toners are being applied to machines that are faster than conventional ones. In this case, a positively chargeable toner or a developer containing the same is required, which has high durability and can withstand a larger number of copies than conventional ones, not only for developing digital latent images but also for developing analog latent images. Ru.

Image quality such as ground blur, reverse fog, and roughness tends to deteriorate in direct proportion to an increase in process speed, and this is particularly noticeable in reverse fog. This development is thought to be due to the fact that as the process speed increases, the opportunities for rubbing between the toner and the toner carrier become smaller and shorter, making it impossible for the toner to obtain sufficient and uniform charging. .

Furthermore, high-end machines often use a method that utilizes static electricity in the step of separating the drum and paper after transferring the image formed on the photoreceptor drum onto transfer paper. In this case, a new process (post charging) is added in which the toner is uniformly charged with the same sign as the developer before the toner is transferred from the photosensitive drum onto the paper. In such an image forming process, when toner is present as fog on the drum, toner that would not be transferred onto the paper in the conventional image forming process is transferred onto the paper due to the newly added charging process. , which appears as fog in the final image.In such an image forming process, it is necessary to control the amount of triboelectric charge more sharply than with conventional toners. At present, it is extremely difficult to use it.

(Problems to be Solved by the Invention) An object of the present invention is to stabilize the amount of triboelectric charge between toner particles, between a toner and a carrier, or between a toner and a toner carrier such as a sleeve in the case of -component development. The object of the present invention is to provide a positively charged toner which has a sharp and uniform triboelectric charge distribution and whose charge amount can be controlled to suit the developing system used.

Another purpose is to develop a toner that is faithful to the digital latent image, that is, the slope of the Vs-09 curve during development is large, and it is possible to increase the density difference between dots, and the edges of the dots are The purpose of the present invention is to provide a toner that reproduces sharp images.

Still another object is to provide a toner that maintains its initial characteristics even when the toner is used continuously over a long period of time, and that does not exhibit fluctuations in the Vs-09 curve.

Still another object is to provide a toner that causes less fog and reverse fog even in an image forming process including post-charging.

Still another object is to provide a toner that reproduces stable images unaffected by changes in temperature and humidity.

Still another object is to provide a toner with excellent storage stability that maintains its initial characteristics even during long-term storage.

[Means and effects for solving the problems] That is, the present invention is characterized in that at least the binder resin 1 has a colorant, a charge control agent, and a unit structure represented by the following general formula [I]. A positively charged electrostatic image developing toner containing the compound.

(R1-M [m]) 3 n/ (m-jri(B
Os) n(f, m, n, 3n/(m-J)
) is a natural number) [I] (However, R represents an organo group, M represents a metal, m is the valence of the metal) The compound having a unit structure represented by the formula [I] used in the present invention is: It is presumed that the M-〇-B structure plays an important role as a positive charge control agent. Therefore, although the organo group bonded to the metal atom is not particularly limited, it has the role of improving the affinity with the binder resin and increasing the charge density of the tin atom. Groups are preferred.

Organo groups include methyl group, ethyl group, butyl group (normal), t-butyl group, and octyl group.

CI'''' C2° alkyl groups such as lauryl group; C6-C2° cyclic alkyl groups such as cyclohexyl group and cyclopentyl group; phenyl group and naphthyl group.

C6-C2° aryl group such as anthryl group; 07-C20 aracyl group such as benzyl group, phenyle group;
C3-C2 acyl groups such as acetyl group and benzoyl group; C2-C2 acyl group such as vinyl group, allyl group, isopropenyl group, etc.
Examples include a C20 alkenyl group; a 02 to C20 alkynyl group such as an ethynyl group and a 2-propynyl group, or a substituent having the above-mentioned group as a basic skeleton.

[I] The positive tribostatic charge control of the compound having the unit structure represented by the formula originates from the M-0 bond. That is, since the electronegativity of the oxygen atom is large, the charge of the M-0 bond is biased toward the oxygen atom, and the charge density of oxygen is high. When designing a charge control agent, it is important to create an electron donor level in the compound by such localization of electrons.
It can be assumed that this is done based on the difference in electronegativity between and O.

Therefore, the difference in electrocathiocity between M and 0 is one of the important elements of the present invention, and is preferably 1.5 or more.

As specific examples of compounds having the structure represented by the general formula [11] as a unit structure, for example, the following may be included.

(1) [(C4H9)2Sn]s (BOs)
2(2) [(<E)H2S n] 3(BO8) 2(
3) [(Hs CO) 2 S n] s (BOs
) 2(4)[C4Ha, C2Ha Sn]s
(BO3)2ra5) [(C,1(,(=)CH2)
2 S n ko 3 (BO3) (6) [(C2
H8)2 Ti]a (BO3)2(7) [(C
2Hs )2 Pbl s (BO3)2(8)
(C2Hs Ajri s (BOs) 2) In the present invention, the charge control agent combined with the compound having the unit structure represented by the formula [I] has a positive triboelectrification effect on metals such as iron powder. Although any pseudo toner can be used as long as it has a triboelectric charge amount of +2 μc/g or more, and more preferably +5 μc/g or more.

Here, the pseudo toner is obtained by kneading 2 parts of a charge control agent with 100 parts by weight of polystyrene at 130°C for 10 minutes.
It is a powder that has been crushed and passed through a 200 mesh sieve. Further, the amount of charge is the value measured by blow-off method after 1 g of this powder and 9 g of iron powder (200 mesh bath, 300 mesh remaining) were heated for 20 seconds.

Examples of charge control agents that can be used in the present invention include nigrosine, azine dyes containing an alkyl group having 2 to 16 carbon atoms, tetrabutylammonium naphthylsulfonate, and dimethyl-benzyl-hexadecyl ammonium chloride. Quaternary ammonium salts, polyamine resins such as vinyl polymers containing amino groups, condensation polymers containing amino groups, organotin compounds such as dibutyltin oxide, metal complexes such as EDTA and acetylacetone, nitrogen-containing compounds such as guanidine and triazine. and so on.

A toner that uses a combination of a conventional positive charge control agent and a compound having a unit structure represented by the formula [I] has particularly excellent characteristics such that there is no decrease in image density even when used continuously for a long period of time, and the initial It is possible to maintain both high quality awards. This is because [in a toner in which a compound having a unit structure represented by the one-part formula and a conventional charge control agent is combined,
This is presumed to be due to the fact that the amount of triboelectric charge is constant and its distribution is sharp. As a result, it is possible to provide a high-density image that is more durable than conventional toners and has less fog and fog reversal. Also, high temperature (32.5℃, 9℃)
0%), low temperature and low humidity (15° C., 10%), it exhibits excellent triboelectric charging ability and can provide high quality images.

In order to uniformly apply a sufficient amount of triboelectric charge to each toner particle, and to control the amount of triboelectricity with high performance without deteriorating due to durability or long-term continuous use, the present invention [
A combination of a compound having a unit structure represented by formula I and a conventional charge control agent is effective.

Colorants used in the present invention include carbon black, lamp black, iron black 1 ultramarine, aniline blue, phthalocyanine blue, phthalocyanine green, banza yellow G, rhodamine 6G, lake, calco oil blue, chrome yellow, quinacridone, benzidine. Any conventionally known dyes and pigments such as yellow, rose bengal, triallylmethane dyes, monoazo dyes, bisazo dyes and pigments can be used alone or in combination.

As the binder resin used in the present invention, ordinary binder resins are used, such as polystyrene.

Monopolymers of styrene and its substituted products such as polyvinyltoluene: styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-acrylic Styrene-acrylic acid represented by ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate, styrene-2-ethylhexyl acrylate copolymer, etc. Ester copolymer;
Styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate, styrene-diethylaminoethyl methacrylate, styrene-dimethylaminopropyl methacrylate, etc. Styrene-methacrylic acid ester copolymers represented by; styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene Copolymers, styrenic copolymers such as styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic ester copolymers; polymethyl methacrylate, polybutyl Methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin.

Examples include phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, etc., and they can be used alone or in combination.

Among these, styrene resins, acrylic resins, and polyester resins are particularly preferred in consideration of development characteristics.

In particular, as binder resins suitable for pressure fixing, the following can be used alone or in combination.

Polyolefins (low molecular weight polyethylene, low molecular weight polypropylene, oxidized polyethylene, etc.), epoxy resins,
Polyester resin, styrene-butadiene copolymer (monomer ratio 5-30:95-70), olefin copolymer (ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer) , ethylene-methacrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ionomer resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, paraffin wax, micro crystalline wax etc.

Further, when the toner of the present invention is used as a two-component developer, it is used in combination with a carrier powder.

All known carriers can be used in the present invention, such as iron powder.

Examples include magnetic powders such as ferrite powder and nickel powder, glass beads, and those whose surfaces have been treated with resin or the like.

Furthermore, the toner of the present invention can further contain a magnetic material and be used as a magnetic toner. In this case, the magnetic material also serves as a coloring agent. The magnetic materials contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; and aluminum, cobalt, and W4.
lead.

Magnesium, tin, zinc, antimony, beryllium,
Bismuth, cadmium, calcium.

Manganese, selenium, titanium, tungsten.

Examples include alloys of metals such as vanadium and mixtures thereof.

These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm, and are contained in the toner in an amount of about 20 to 200 parts by weight per 100 parts by weight of the resin component, particularly preferably 100 parts by weight of the resin component. 40 to 150 parts by weight.

Further, it can be used in combination with conventionally known charge control agents as long as it does not adversely affect the developer of the present invention.

Further, when the developer of the present invention is mixed with additives as necessary, better results can be obtained. Examples of additives include lubricants such as Teflon and zinc stearate, abrasives such as cerium oxide and silicon carbide, and colloidal silica.

Flow agents such as aluminum oxide, anti-caking agents or, for example, carbon black.

Examples include conductivity imparting agents such as tin oxide, fixing aids such as low molecular weight polyethylene, and anti-offset agents. Further, a small amount of white fine particles of opposite polarity can be used as a developability improver.

To prepare the electrostatic image developing toner according to the present invention, the charge control agent according to the present invention is a vinyl-based charge control agent.

A non-vinyl thermoplastic resin, a pigment or dye as a coloring agent, and if necessary, a magnetic material, additives, etc. are thoroughly mixed in a ball mill or other mixer, and then heated in a heat kneading machine such as a heated roll, kneader, or extruder. A pigment or dye is dispersed or dissolved in the resin by melting, kneading, and kneading to make the resins compatible with each other, and after cooling and solidifying, it is crushed and classified to obtain a toner with an average particle size of 5 to 20 μm. I can do it.

Alternatively, the material can be obtained by dispersing the material in a binder resin solution and then spray-drying it, or by mixing the specified material with the monomers that should constitute the binder resin to form an emulsified suspension and then polymerizing it. A polymerization method to obtain a toner, a method of forming a capsule toner consisting of a core and a shell, etc. can be applied.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but these are not intended to limit the present invention in any way. Note that all parts in the following formulations are parts by weight.

Example 1 The above materials were thoroughly mixed using a printer and then kneaded using two rolls heated to 150°C. After the kneaded material was left to cool naturally, it was roughly pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain black fine powder with a number average particle size of 10μ. Obtained. The fine powder 100
0.4 part of fine silica powder was mixed in a sample mill to prepare a toner.

Images of this developer were obtained using an electrophotographic printer using an amorphous silicon photoreceptor and evaluated. In addition, when measured by the blow-off method, the tribo value of the developer was +10.3 μc.
/g.

FIG. 5 shows an embodiment of an electrophotographic printer to which the developer of the present invention can be applied. The electrical signal input to the laser modulation unit 1 is output as a modulated laser beam, and is scanned in the longitudinal direction of the photosensitive drum 4 by the scanner mirror 2 and f/θ lens 3. The photosensitive drum 4 rotates in the direction of the arrow, making it possible to scan the laser beam two-dimensionally.

As a photoreceptor, amorphous silicon, selenium, CdS
, an organic photoreceptor, etc. are used, and are sensitized to have sensitivity to the wavelength (780 nm to 800 nm) of a semiconductor laser, for example. In this embodiment, an amorphous silicon photoreceptor is used as such a photoreceptor, and after leveling the potential on the surface of the photoreceptor with an AC static eliminator 5, it is charged to 380V with a charger 6. Thereafter, laser beam exposure is performed to form a dot latent image on the photoreceptor by an image scanning method using a ternary dither method. The ternary M level is shown in Figure 3 (a).
It is formed by pulse width modulation of laser light.

The latent image potential was 250V at H level and 120V at M level.

Such a dot latent image was reversely developed by a one-component insulating magnetic toner developer 9 (or 11) containing a developer containing the above-mentioned toner. At this time, a developing bias of 280 V was applied as a DC component.

The thus developed image was then transferred onto the transfer paper 12 by the transfer charger 11 and fixed onto the transfer paper 12 by the fixing device 13. Further, toner remaining on the photosensitive drum 4 without being transferred is collected by a cleaner 14. The image thus formed on the transfer paper has an H level of 1.37.
The M level was 0.61, and the image density in the solid area was sufficiently high, the dots were sharp, and the photographic image, which serves as a guide for halftone reproduction, was also clearly reproduced. Also, after copying 100,000 sheets repeatedly, the H level fluctuation was ±0.0.
7 or less 2M level fluctuation is within ±0.15, Vs
- No major changes were required in the Dp characteristics. moreover,
When the environmental conditions were set to 35° C., 85% and 15° C., 10%, good images were obtained in both cases, similar to those at room temperature, and no major changes were observed even after repeated use of 100,000 sheets.

Furthermore, this developer was stored for half a year, but there were no major changes in its initial characteristics.

Furthermore, fogging and reverse fogging were not a problem throughout the durability test.

Example 2 The above materials were kneaded, pulverized and classified in the same manner as in Example 1 to obtain a sepia colored fine powder with a number average particle size of 9 μm. The fine powder 10
0 part and 0.5 part of silica fine powder are mixed in a sample mill,
I used it as a toner.

The obtained sepia image showed a value of 1.32 at H level and 0.59 at M level, the image density in the solid area was sufficiently high, the dots were sharp, and it was considered a photographic image as a guide for reproduction of halftones. was also beautifully reproduced. , I made 100,000 copies repeatedly, but the H level fluctuation was within ±0.07.
The variation in the M level was within ±0.15, and no practical change was observed in the Vs-Dp characteristics. Furthermore, when the environmental conditions were set to 35° C., 85% and 15° C., 10%, both exhibited a good sepia color similar to that at room temperature.

Example 3 The above materials were thoroughly mixed in a blender and then kneaded with a two-wood roll heated to 150°C. After allowing the kneaded mixture to cool naturally, it is coarsely pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a fine powder with a particle size of 5 to 20μ (toner). ) was obtained. To this fine powder, 0% of the positively chargeable silica fine powder used in Example 1 was added.
．． 4 wt% was added externally.

A developer was prepared by mixing 5 parts of the externally added fine powder with 100 parts of iron powder carrier having an average particle size of 50 to 80 microns.

Next, by a conventionally known electrophotographic method on the OPC5 light body,
A negative electrostatic image was formed, and this was powder-developed using the above-mentioned developer using a magnetic brush method to create a toner image, which was transferred to plain paper and heat-fixed.

The resulting transferred image had a sufficiently high density of 1.38, had no fogging, and had no toner scattering around the image, resulting in a good image with high resolution.

Further, during durability, the above-mentioned filming phenomenon related to toner on the photoreceptor was not observed at all, and no problems were found in the cleaning process. Also, there was no trouble in the fixing process at this time, ioo, oo.

At the end of the sheet durability test, the fuser was observed, and there were no scratches or damage to the rollers, and there was almost no staining due to offset toner, so there were no practical problems at all.

Further, when the environmental conditions were set to 35° C. and 85%, the image density was 1.30 at room temperature, which was a value with almost no change, and a clear image was obtained without fogging or scattering.

Next, when a transferred image was obtained at 15° C. and 10% low temperature and low humidity, the image density was as high as 1.31, solid black was developed and transferred extremely smoothly, and the image was excellent with no scattering or hollow spots.

Example 4 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After the kneaded material was allowed to cool naturally, it was roughly pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a black fine powder with a number average particle size of 1 μm. Obtained.

0.4 parts by weight of the positively charged silica fine powder used in Example 1 was added to 100 parts by weight of the above fine powder to prepare a developer. Using this developer, an image was obtained and evaluated in the same manner as in Example 1, and as in Example 1, good results were obtained.

[Brief explanation of the drawing]

Figures 1(a) and (b) are diagrams showing the concept of a multivalued dither matrix, and Figures 2(a) and (b) and Figure 3(a) are diagrams showing the concept of a multilevel dither matrix.
) and (b) are diagrams showing characteristic graphs showing the exposure intensity distribution and the potential distribution of an electrostatic latent image when performing three-value recording;
The figure is a graph showing the development characteristics of a multivalued latent image, and FIG. 5 is a diagram schematically showing a specific example of an electrophotographic printer to which the toner of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Laser modulation unit, 2... Scanner mirror, 4... Photosensitive drum, 5... AC static eliminator, 6... Charger, 9... Developer, 11... Transfer Charger.

Claims (1)

[Claims] (1) A toner for developing an electrostatic image, characterized in that the binder resin contains at least a colorant, a charge control agent, and a compound having a unit structure represented by the following general formula [I]. (Rl-M[m])3n/(ml)(BO_3)n(
l, m, n, 3n/(ml) are natural numbers) [I] (However, R represents an organo group, M represents a metal. m is the valence of the metal)