JPH0740148B2 - Positively charging non-magnetic toner for electrostatic image development - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel positively chargeable non-magnetic toner for developing an electrostatic charge image in electrophotography, electrostatic recording, electrostatic printing and the like.

BACKGROUND ART Conventionally, as an electrophotographic method, various methods are described in U.S. Pat.No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748, but in short, they are photoconductive. A uniform electrostatic charge is applied onto the insulating layer, and an electrostatic latent image is formed by irradiating the insulating layer with a light image,
Then, the latent image is developed and visualized by fine powder called toner in the technical field, and if necessary, the powder image is transferred to paper or the like, and then fixed by heating, pressurizing, or solvent vapor.

As a developing method applied to these electrophotographic methods,
It is roughly classified into a dry development method and a wet development method. The former is further divided into a method using a two-component developer and a method using a one-component developer. Among the two-component developing methods, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using a fur, etc., depending on the type of carrier that carries the toner.

The one-component developing method includes a powder cloud method in which toner particles are sprayed, a contact developing method in which toner particles are directly brought into contact with an electrostatic latent image surface for development (contact development, or toner development). (Also referred to as development), a jumping development method in which toner particles are not directly contacted with the electrostatic latent image surface, but the toner particles are charged and fly toward the latent image surface by the electric field of the electrostatic latent image, magnetic conductivity. There is a magnetic dry method in which toner is brought into contact with the electrostatic latent image surface to develop the toner.

As a toner applied to these developing methods, a fine powder in which a dye or a pigment is dispersed in a natural or synthetic resin is conventionally used. For example, particles in which a colorant is dispersed in a binder resin such as polystyrene and finely pulverized to about 1 to 30 μm are used as a toner. As the magnetic toner, one containing magnetic particles such as magnetite instead of or in addition to the above-mentioned dye or pigment is used. In the case of a system using a so-called two-component developer, the toner as described above is usually used by being mixed with carrier particles such as glass beads and iron powder.

Further, positive or negative electric charges are given to the toner in advance depending on the polarity of the electrostatic latent image to be developed.

To impart an electric charge to the toner, it is possible to use only the triboelectric chargeability of the resin, which is a component of the toner, but in this method the toner chargeability is small, so the image obtained by development is easily fogged and is not clear. It will be Therefore, in order to impart a desired triboelectric charging property to the toner, a charge control agent such as a dye or a pigment which enhances the charging property is added.

Examples of charge control agents known in the field of electrophotography today include the following.

(1) There are the following for controlling the toner to be positively charged.

Nigrosine, an azine type dye containing an alkyl group having 2 to 16 carbon atoms (Japanese Examined Patent Publication No. 42-1627), a basic dye (for example, CI Basic Yellow 2 (CIBasic Yellow
2 (CI41000)), C. Eye. basic. Yellow 3 (CIBasic Yellow 3), C. Eye. basic. Red 1 (CIBasic Red 1 (CI45160)), sea. Eye. basic. Red 9 (CIBasic Red 9
(CI42500)), C. Eye. basic. Violet 1 (CIBasic Violet 1 (CI42535)), C.I.
Eye. basic. Violet 3 (CIBasic Violet
3 (CI42555)), C. Eye. basic. Violet 10 (CIBasic Violet 10 (CI45170)), sea. Eye. basic. Violet 14 (CIBasic Vi
olet 14 (CI42510)), sea. Eye. basic. Blue 1 (CIBasic Blue 1 (CI42025)), sea. Eye. basic. Blue 3 (CIBasic Blue 3 (CI51
005), C. Eye. basic. Blue 5 (CIBasic
Blue 5 (CI42140)), sea. Eye. basic. Blue 7 (CIBasic Blue 7 (CI42595)), sea. Eye. basic. Blue 9 (CIBasic Blue 9 (CI52
015)), C. Eye. basic. Blue 24 (CIBas
ic Blue 24 (CI52030)), C. Eye. basic. Blue 25 (CIBasic Blue 25 (CI52025)), sea. Eye. basic. Blue 26 (CIBasic Blue 26
(CI44045)), C. Eye. basic. Green 1 (CIBasic Green 1 (CI42040)), sea. Eye.
basic. CI Basic Green 4 (CI420
00)), CI45170 etc.). Lake pigments of these basic dyes, (as a laker, phosphotungstic acid,
Phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide,
Ferrocyanide), C. Eye. Solvent. Black 3 (CISolvent Black 3 (CI26150)), Hansa Yellow G (CI11680), C.I. Eye. Moldant. Black 11 (CIMordant Black 11), sea. Eye. Pigment. Black 1 (CIPigment Black
1), Gilsonite, asphalt, etc.

Quaternary ammonium salts such as benzylmethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, organotin compounds such as dibutyltin oxide, metal salts of higher fatty acids, glass, mica, inorganic fine powders such as zinc oxide, EDTA, Metal complexes of acetylacetone, etc.

Polyamine resins such as amino group-containing vinyl polymers and amino group-containing condensation polymers.

(2) There are the following for controlling the toner to be negatively charged.

Japanese Patent Publication No. 41-20153, 43-27596, 44-6397, 45-
Metal complex salts of monoazo dyes described in No. 26478 and the like.

JP-B-55-42752, 58-41508, 59-7384, 59-
Salicylic acid, naphthoic acid, described in No. 7385,
A metal complex of dicarboxylic acid such as Co, Cr and Fe.

Sulfonated copper phthalocyanine pigment.

Styrene oligomer with nitro group and halogen introduced. Chlorinated paraffin, melamine resin, etc.

However, as described above, the use of conventional charge control agents still has many problems to be improved. That is,
Many of these charge control agents are derived from dyes and pigments, and generally have a complicated structure, inconsistent properties, poor stability, and strong coloring properties. Recently, some of the proposed ones are different in system from the ones mentioned above, but none of them are superior in overall performance to those of the dye / pigment system, and despite many disadvantages as described below, In most cases, dye-pigment type charge control agents are used.

That is, these charge control agents are usually added to a thermoplastic resin which is also a binder resin, and are contained in a toner prepared through processes such as thermal melting dispersion, pulverization and classification. In the process, the dye / pigment type charge control agent described above often causes a problem. For example, as described above, these charge control agents are poor in stability as substances, and are easily decomposed or deteriorated by decomposition during thermal kneading, mechanical shock, friction, changes in temperature and humidity conditions, etc. The phenomenon that the property deteriorates is likely to occur. Further, when a toner containing these dyes and pigments as a charge control agent is developed in a copying machine, the charge control agent decomposes or deteriorates as the number of times of copying increases, causing deterioration of the toner during repeated copying operations. There is.

Further, since it is extremely difficult to uniformly disperse these charge control agents in the thermoplastic resin, there is a fatal problem that a difference in the triboelectric charge amount between the toner particles obtained by pulverization causes a difference. Have Therefore, various methods have heretofore been used to make the dispersion more uniform. For example,
The basic nigrosine dye is used by forming a salt with a higher fatty acid in order to improve the compatibility with the thermoplastic resin.
Often, unreacted fatty acid or salt dispersion product is exposed on the toner surface and contaminates the carrier or the toner carrier, causing a decrease in toner fluidity, fog, and a decrease in image density. . Alternatively, in order to improve the dispersion of these charge control agents in the resin, a method of mechanically pulverizing and mixing the charge control agent powder and the resin powder in advance and then hot-melt kneading is used. However, the original poor dispersion cannot be avoided, and in the current situation, sufficient charge uniformity for practical use has not yet been obtained.

In addition, most of the substances generally known as charge control agents have a dark color, and thus there is a problem that they cannot be contained in a vivid chromatic color developer.

Further, many charge control agents are hydrophilic, and due to poor dispersion in these resins, the dye is exposed on the toner surface when pulverized after melt kneading. Therefore, when the toner is used under high humidity conditions, there is a problem that a high quality image cannot be obtained because the charge control agent is hydrophilic.

Thus, when the conventional charge control agent is used in the toner,
Between toner particles, or between toner and carrier,
The charge amount generated on the surface of the toner particles varies between the toner carrier such as the toner and the sleeve, and troubles such as development fog, toner scattering and carrier contamination are likely to occur. Further, this obstacle appears as a remarkable phenomenon when the number of times of copying is increased, which is not suitable for a copying machine.

Further, under high humidity conditions, the transfer efficiency of toner images is significantly reduced, and many of them cannot be used. Even at room temperature and normal humidity, when the toner is stored for a long period of time, it deteriorates due to instability of the charge control agent used and often becomes unusable due to poor chargeability.

Furthermore, when a conventional charge control agent is used for a toner, the charge control agent itself adheres to the surface of the photoconductor due to long-term use, or the presence of the charge control agent promotes the adhesion of the toner (the occurrence of a filming phenomenon). In many cases, the cleaning process of the copying machine is inconvenient, such as adversely affecting the latent image formation, causing scratches on the surface of the photoconductor or a cleaning member such as a cleaning blade, or promoting wear of the member.

Furthermore, when a conventional charge control agent is used in a toner, it often causes a great influence on the heat melting property of the toner and deteriorates the fixing performance. In particular, there are inconveniences such as deterioration of high-temperature offset performance, increase of sticking property of paper or the like to a roller at the time of heat roll fixing, and reduction of durable life of the roller.

As described above, many problems are observed in the conventional charge control agents, and it is strongly requested in the technical field to solve these problems, and many improved techniques have been proposed so far. The reality is that we have not yet found anything practically satisfying.

OBJECT OF THE INVENTION It is a general object of the present invention to provide a new technique for positive polarity charge control of toner which overcomes these problems.

A more specific object of the present invention is that the triboelectric charge amount of positive polarity is stable such as between toner particles or between toner and carrier, between toner and a toner carrier such as a sleeve in the case of one-component development, and It is intended to provide a positively chargeable non-magnetic toner having a triboelectric charge amount distribution which is sharp and uniform and which can be controlled to a charge amount suitable for a developing system used.

Still another object is a developer that faithfully develops and transfers a latent image, that is, adhesion of toner in the background area at the time of development, that is, no fog or toner scattering around the edge of the latent image, The purpose of the present invention is to provide a positively chargeable non-magnetic toner having high image density and good halftone reproducibility.

Still another object is to provide a positively chargeable non-magnetic toner that maintains the initial properties even when continuously used for a long period of time and does not cause aggregation or change in charging properties.

Still another object is to positively charge non-magnetic toner that reproduces a stable image that is not affected by changes in temperature and humidity, especially for transfer efficiency that does not cause scattering or transfer omission during transfer at high humidity and low humidity. It is to provide a highly positively charging non-magnetic toner.

Still another object is to provide a positively chargeable non-magnetic toner having a bright chromatic color.

Still another object is to provide a positively chargeable non-magnetic toner excellent in storage stability that maintains initial properties even after long-term storage.

Still another object is to provide a positively chargeable non-magnetic toner which does not stain, wear or scratch the electrostatic latent image surface and can be easily cleaned.

Still another object is to provide a positively chargeable non-magnetic toner having good fixing characteristics, particularly a positively chargeable non-magnetic toner having no problem in high temperature offset and the like.

SUMMARY OF THE INVENTION The present invention relates to a positively chargeable non-magnetic toner for developing an electrostatic charge image, which contains a binder resin, a colorant, a wax and an ammonium borofluoride salt represented by the following general formula.

(However, R _{1 to} R ₄ in the formula represent an alkyl group or an aralkyl group, one of which is an alkyl group having 16 or more carbon atoms.) The represented ammonium borofluoride salt not only exhibits excellent positive charge controllability when contained in the toner, but is stable under heating and use over time, has little hygroscopicity, and is essentially colorless. The present invention has been completed by finding that it has a very effective characteristic for achieving the above-mentioned object, that is, that it is a light color.

Hereinafter, the present invention will be described in more detail. In the following description, “part” and “%” representing the quantitative ratio are based on weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the ammonium borofluoride salt used as the charge control agent, R _{1 to} R ₄ in the above general formula are each an alkyl group or an aralkyl group, and one of them has 16 or more carbon atoms. And an alkyl group of.

More specifically, the following are typical examples of the ammonium borofluoride salt represented by the above general formula.

[Compound example] These ammonium borofluoride salts are synthesized by a known method. That is, when the corresponding halogenated quaternary ammonium salt is dissolved in an appropriate solvent and borofluoric acid (HBF ₄ ) is added dropwise thereto, a white precipitate of ammonium borofluoride is easily obtained. More specifically, for example, the compound of the above example (1) is obtained by adding an aqueous solution of heptadecylbenzylmethylammonium chloride (for example, manufactured by Tokyo Chemical Industry Co., Ltd.) to an aqueous solution of borofluoric acid (for example, manufactured by Kishida Chemical Co., Ltd.). Is added dropwise and the resulting white precipitate is separated to obtain a white powder.

In general, ammonium borofluoride has an average particle size of 10 to
It is preferable that the toner has a particle size in the range of 0.01 μ, particularly 2 to 0.1 μ for use in toner preparation.

The toner of the present invention can be obtained by blending the above ammonium borofluoride salt into a toner (fine colored powder) containing a binder resin, a colorant and a wax as essential components. As a form of compounding, either a so-called internal addition form in which the toner is uniformly or encapsulated in a toner or a so-called external addition form in which the toner is mixed and attached to the toner can be adopted.

When internally added, the amount of ammonium borofluoride salt used is
The type of the binder resin, the presence or absence of additives used as necessary, it is determined by the toner manufacturing method including the dispersion method, it is not limited in general, preferably 100 weight of the binder resin It is used in the range of 0.1 to 10 parts by weight (more preferably 0.5 to 5 parts by weight) per part.

If necessary, a conventionally known charge control agent can be used in combination with the charge control agent according to the present invention.

The binder resin of the toner includes homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and their substitution products; styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-
Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-methylmethacrylate copolymer, styrene-ethylmethacrylate copolymer, styrene-butylmethacrylate copolymer, styrene-α-chloromethylmethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl Ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid Copolymer, styrene Styrene copolymers such as maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester,
Examples thereof include polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin and phenol resin, which can be used alone or in combination.

As the colorant, carbon black, lamp black,
Ultramarine, Nigrosine Dye, Aniline Blue, Phthalocyanine Blue, Phthalocyanine Green, Hansa Yellow G, Rhodamine 6G Lake, Calco Oil Blue, Chrome Yellow, Quinacridone, Benzidine Yellow, Rose Bengal, Triarylmethane Dye, Monoazo, Disazo Dyes and Pigments Conventionally known dyes and pigments may be used alone or in combination.

Examples of the wax include low molecular weight polyethylene wax and low molecular weight polypropylene wax used in Examples described later.

Further, the toner of the present invention may be mixed with additives other than the above if necessary. Examples of the additives include lubricants such as Teflon and zinc stearate, fluidity imparting agents such as colloidal silica and aluminum oxide, and anti-caking agents.

To prepare the toner for developing an electrostatic image of the present invention, the ammonium borofluoride salt according to the present invention is used as a binder resin as described above, a wax and a pigment or dye as a colorant, and additives as required. Is thoroughly mixed with a ball mill or other mixing machine, and then melted and kneaded with a heat kneader such as a heating roll, kneader, or extruder to disperse or dissolve the pigment or dye in the resin to make them compatible with each other. After cooling and solidification, pulverization and classification can be performed to obtain a toner having an average particle size of 5 to 20 μm. Alternatively, a method in which the material is dispersed in a binder resin solution and then spray-dried, or a predetermined material is mixed with a monomer to form the binder resin to form an emulsified suspension and then polymerized A method such as a polymerization method for obtaining a toner and a toner manufacturing method can be applied.

The toner produced by these methods can be used for development for developing an electrostatic charge image in electrophotography, electrostatic recording, electrostatic printing and the like by a conventionally known means.

EFFECTS OF THE INVENTION As described above, the toner of the present invention containing an ammonium borofluoride salt as a charge control agent has a uniform positive triboelectric charge amount between toner particles, and the charge amount is easily controlled. Further, the toner is extremely stable without deteriorating during use so that the triboelectric charge amount does not vary or decrease. Therefore, the above-mentioned obstacles such as developing fog, toner scattering, contamination of electrophotographic photosensitive material and copying machine are eliminated, and toner aggregation, agglomeration and low temperature fluidity during storage, which have been major problems in the prior art, are eliminated. It is a toner that does not cause a phenomenon and withstands long-term storage, and has excellent abrasion resistance, fixing property, and adhesiveness of a toner image.

The excellent effect of such a toner is that when it is used in a repetitive transfer type copying system in which the operations of charging, exposing, developing and transferring are continuously repeated, the effect is further expanded. Further, since there is little color tone disorder due to ammonium borofluoride salt, it is possible to form a color image of excellent color when used as a color electrophotographic toner.

Hereinafter, the present invention will be described more specifically by way of examples.

Example 1 Styrene / butyl acrylate copolymer (80/20) 100 parts (Weight average molecular weight Mw: about 300,000) Carbon black (Mitsubishi # 44) 10 parts Low molecular weight polyethylene wax 2 parts Borofluoride of the above example (1) Ammonium salt 2 parts The above materials were well mixed in a blender and then kneaded with a two-roll roller heated to 150 ° C. After allowing the kneaded product to cool naturally, it is roughly crushed with a cutter mill, crushed with a fine crusher using a jet stream, and further classified with an air classifier,
A positively chargeable non-magnetic toner fine powder having a particle size of 5 to 20 μm was obtained.

A developer was prepared by kneading 100 parts of an iron powder carrier having a particle size of 50 to 80 μm with 5 parts of the above toner.

Further, the triboelectric charge amount of the positively chargeable non-magnetic toner in the developer was measured by a usual blow-off method.

Then, a negative electrostatic image is formed on the OPC photosensitive member by a conventionally known electrophotographic method, and this is powder-developed by the magnetic brush method using the above developer to form a toner image, which is transferred to plain paper. Heated and fixed. The obtained transferred image had a sufficiently high density of 1.32, no fog, no toner scattering around the image, and a good image with high resolution was obtained. Transfer images were continuously prepared using the above-mentioned developers and durability was examined. The transferred images after 30,000 sheets were completely achromatic images as compared with the initial images.

Further, during the durability test, the filming phenomenon related to the toner on the photosensitive member was not observed at all, and no problem in the cleaning process was found. Further, at this time, there was no trouble in the fixing step, and at the end of the durability test of 30,000 sheets, the fixing machine was observed, but there were no scratches or damage on the roller, and there was almost no stain due to the offset toner, and there was no problem in practice.

Also, when the environmental conditions were 35 ° C and 85%, the image density was
It was a value of 1.20, which was almost unchanged from room temperature and normal humidity, a clear image was obtained without fogging and scattering, and durability was hardly changed up to 30,000 sheets. Next, when a transfer image was obtained at a low temperature and low humidity of 15% at 10%, the image density was as high as 1.33, and the solid black was developed and transferred very smoothly, and was an excellent image with no scattering or voids. A durability test was conducted under these environmental conditions. Copies were made continuously and at intervals, but the density fluctuation was ± 0.2, which was sufficient for practical use up to 30,000 sheets.

Comparative Example 1 A developer was obtained in the same manner as in Example 1 except that 2 parts of Nigrosine dye (Nigrosine base EX manufactured by Orient Chemical Industry) was used in place of 2 parts of the ammonium borofluoride salt of Example (1) above, and development was carried out. Transfer and fixing were performed, and an image was similarly obtained. Fog was small at room temperature and normal humidity, but the image density was low at 1.06, line drawings were scattered, and solid black was noticeable.
When the durability was examined, the density decreased to 0.83 after 30,000 sheets.

Also, during the durability test, the toner material formed a thin streak-like film on the surface of the photoreceptor from around 10,000 sheets and appeared as lines on the image. This is so-called filming, and it is considered that the charge control agent changes the lubricity of the toner powder.

Further, at the time of endurance, a fixed image was likely to be caught in the fixing roller in the fixing step, and the peeling property from the roller was difficult.

The image density was 0.88 when the image was obtained under the conditions of 35 ℃ and 85%.
It became low and fog, splattering, and rubbing increased. The transfer efficiency was also low at 69%.

The image density was 0.91 when the image was obtained under the condition of 15 ℃ and 10%.
It was low, and scatter, fog, and rubbing were noticeable. Although continuous images were printed, the density became 0.53 after about 30,000 sheets, making it unusable.

Comparative Example 2 Instead of 2 parts of ammonium borofluoride salt of the above Example (1), Example 1 except using 3 parts of ammonium borofluoride salt of
A developer was obtained in the same manner as described above, and development transfer transfer fixing was performed to obtain an image in the same manner.

Detailed results are shown in Tables 1 and 2, but the triboelectric charge amount and the image density were lower than those in Example 1.

Comparative Example 3 Instead of 2 parts of ammonium borofluoride salt of the above Example (1), Example 1 except that 2 parts of ammonium borofluoride salt of
A developer was obtained in the same manner as above, and development, transfer and fixing were carried out to obtain an image in the same manner.

Detailed results are shown in Tables 1 and 2, but the triboelectric charge amount and the image density were lower than those in Example 1.

Comparative Example 4 Instead of 2 parts of ammonium borofluoride salt of the above Example (1), Example 1 except that 2 parts of ammonium borofluoride salt of
A developer was obtained in the same manner as above, and development, transfer and fixing were carried out to obtain an image in the same manner.

The detailed results are shown in Tables 1 and 2, but the triboelectric charge amount and the image density were slightly lower than those in Example 1.

Example 2 Styrene / butyl acrylate (80/20) copolymer 100 parts (Average molecular weight Mw: about 300,000) Copper phthalocyanine blue pigment 5 parts Low molecular weight polypropylene wax 2 parts 2 parts ammonium borofluoride salt of the above example (1) The above materials were well mixed with a blender and then kneaded with two rolls heated to 150 ° C. After allowing the kneaded product to cool naturally, it is roughly crushed with a cutter mill, crushed with a fine crusher using a jet stream, and further classified with an air classifier to obtain toner fine powder with a particle size of 5 to 20μ. Obtained.

Further, the triboelectric charge amount of the toner was measured by a usual blow-off method.

Next, 100 parts of the toner was mixed with 50 parts of magnetic particles having a particle size of 50 to 80 μm to obtain a developer.

This developer is stored in the developer container 1 of the developing device shown in the accompanying drawings.
And developed. That is, in this apparatus, a cylindrical toner carrier 2 made of stainless steel, the surface of which is roughened so as to substantially close the container, is accommodated in the lower opening of the container 1, which has a peripheral speed of 66 mm in the direction of arrow a. /
Rotated in seconds. On the other hand, an iron blade 3 having a tip at a position of 200 μm from the sleeve surface is arranged at the outlet of the sleeve 1 on the downstream side in the rotation direction of the sleeve 1, and a fixed magnet 4 is arranged in the sleeve 2. The N pole, which is the main magnetic pole, is arranged so that the angle θ between the line connecting the sleeve and the sleeve center and the sleeve center and the blade 3 tip is 30 °. Under such a condition, as the sleeve 2 rotates, the magnetic brush 5 is formed in the container 1 by the magnetic particles contained in the developer, and the magnetic brush 6 is preferentially distributed above the toner 6. Is taken in and supplied to the surface of the sleeve 2 and circulates along the periphery of the sleeve 2 below the container 1 to form a thin layer 16 of toner on the surface of the sleeve 2 which has passed the blade 3.

In this example, the thickness thus formed is about 80 μm.
Approximately 30 in the development area (closest area) due to the thin toner layer
-600V, -1500V in dark areas on the photoconductor drum 7 facing each other at a distance of 0 μm and rotating in the direction of arrow b at a peripheral speed of about 60 mm / sec
The negative electrostatic image of was developed. At this time, the frequency of 80
A bias voltage having a peak-to-peak value of 1.4 KV and a center value of -300 V was applied between the sleeve 2 and the photosensitive drum 7 at 0 Hz.

When images were printed in this way, good images with a vivid blue color were obtained, and after printing 1,500 sheets, even if the toner / magnetic particle ratio was 10 parts / 50 parts, almost all images were printed. No change in density was observed, and after that, while replenishing toner, 3
A good image was obtained even when images were printed up to 10,000 sheets.

Room temperature-normal humidity (25 ° C, 60% R
H), high temperature and high humidity (35 ℃, 85% RH), low temperature and low humidity (15 ℃, 10
The results of the evaluation of (% RH) under various environmental conditions are summarized in Tables 1 and 2 below.

[Brief description of drawings]

The drawing is a schematic cross-sectional view of an example of a developing device suitable for applying the toner according to the present invention. 1 ... Developer container, 2 ... Toner carrier, 3 ... Doctor blade, 4 ... Fixed magnet, 5 ... Magnetic brush, 6 ...
... toner, 7 ... electrostatic latent image carrier, 16 ... thin layer toner.

Claims (2)

[Claims] 1. A positively chargeable non-magnetic toner for developing an electrostatic charge image, which comprises a binder resin, a colorant, a wax and an ammonium borofluoride salt represented by the following general formula. (However, R _{1 to} R ₄ in the formula represent an alkyl group or an aralkyl group, and any one of them is an alkyl group having 16 or more carbon atoms.) 2. The binder resin comprises a styrene-based copolymer,
Claim 1 wherein the wax comprises a low molecular weight polyethylene wax or a low molecular weight polypropylene wax.
Item 4. A positively chargeable non-magnetic toner for developing an electrostatic charge image according to item.