JP3454257B2 - Toner for developing electrostatic images - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic copying machine in which an image is formed by utilizing an electrophotographic method, an electrostatic recording method, etc.
The present invention relates to toner used for developing an electrostatic latent image in a laser beam printer or the like. More specifically, the present invention relates to an electrophotographic toner having excellent copy quality, durability, and stability.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic copying machine or a laser beam printer using an electrophotographic method, an electrostatic recording apparatus using an electrostatic recording method, etc. have been used to make a copied image or a recorded image (hereinafter, both are combined. , Simply referred to as "copy image") is widely performed. For example, in an electrophotographic copying machine or a laser beam printer using the electrophotographic method, image formation is usually performed as follows. That is, first, an electrostatic latent image carrier made of a photosensitive drum such as amorphous silicon, selenium, or an organic semiconductor is positively or negatively charged by a charger, and then the charged electrostatic latent image carrier is slit exposed. Alternatively, beam exposure is performed to form an electrostatic charge image on the electrostatic latent image carrier. The formed electrostatic charge image is developed by a developer, the toner image after development is transferred to a transfer target such as paper, and the transferred toner image is fixed by a heat roll, a pressure roll or the like to form a copy image. . As a method of developing the electrostatic image,
(A) A two-component dry developing method such as a magnetic brush method or a cascade method using a two-component dry developer containing a carrier such as iron powder or glass powder and a toner containing a resin and a colorant as a main component, ( There are b) a one-component developing method in which development is performed using only toner without using a carrier, and (c) a liquid developing method using an insulating carrier liquid. The two-component developing method is generally a non-magnetic two-component developing method using an insulating non-magnetic toner containing carbon black in the toner as a black developer. The toner used in the two-component developing method and the one-component developing method usually contains a binder resin, a colorant and a charge control agent as components, and if necessary, an additive referred to as an external additive. Colored fine particles.

In these toner components, the charge control agent has the ability to impart triboelectric charging properties to the toner and holds positive or negative charges. As the positively chargeable charge control agent, there are generally quaternary ammonium salts, triphenylmethane dyes and pigments, and nigrosine dyes.
Examples of the negatively chargeable charge control agent generally include metal complexes of monoazo dyes and metal-containing dyes such as chromium-containing organic dyes.

In recent years, as a photoreceptor for an electrophotographic copying machine or a printer, a photoreceptor using an organic photoreceptor has become popular, and a positively chargeable toner is required as a developer for a copying machine or the like using the organic photoreceptor. Has been. Therefore, the positive charge control agent plays a very important role.

However, when the quaternary ammonium salt is used alone, the ability to impart triboelectric charging property to the toner is low, and when repeatedly used in a copying machine or printer for continuous copying, a white background portion called fog appears. An undesired phenomenon such as an increase in background stain (hereinafter referred to as fog) or a decrease in image density occurs.

Further, when the triphenylmethane dyes and pigments are used alone, they have the ability to impart excellent triboelectric charging properties to the toner under low temperature and low humidity and under normal temperature and normal humidity, but the charge amount decreases under high temperature and high humidity. However, an unfavorable phenomenon such as an increase in fog or a decrease in image density occurs.

On the other hand, the nigrosine dye has the ability to impart a relatively excellent triboelectric charging property to the toner,
However, the properties such as triboelectrification performance or thermal performance greatly differ depending on the manufacturing method, and it is difficult to satisfy all the performances required for the toner. Further, the nigrosine-based dye has a problem that it is difficult to uniformly disperse it in the binder resin, and when it is made into a toner, the nigrosine-based dye may be dispersed or poorly distributed. Such a toner does not have a uniform charge amount distribution, and therefore exhibits excellent image characteristics at the initial stage of copying, but fog increases as the number of copies increases. Further, under low temperature and low humidity, the proportion of the toner having a high charge amount becomes excessive, and a wavy pattern due to the toner is generated on the sleeve surface, which may appear in an image.

Furthermore, the toner is kept at a high temperature for a long time (40 to 5).
(0 ° C.), the surface condition of the toner causes a change with time to deteriorate the quality of the copied image, and is a numerical value indicating the ratio of the amount of the toner transferred to a transfer target such as paper. Of the toner and scattering of toner inside the copying machine or printer. That is, the image quality is excellent in the freshly manufactured state, the fog is small, the transfer rate of the toner is high, and the toner scattering in the machine is small. As the number of copied sheets increases, the fog increases, the transfer rate of the toner significantly decreases, and the scattering in the machine further increases. The decrease in the transfer rate is not only an economical disadvantage that a large amount of toner is used due to the fact that the proportion of toner actually transferred is low, but also a large amount of untransferred toner remains on the image carrier and excessively collects in the collecting section. This may cause the toner to fly or cause the toner to fly inside the machine. Therefore, the transfer rate is important as the required quality of toner.

As an attempt to improve these drawbacks,
Type and amount of colorant, amount of charge control agent, type and amount of external additive such as fluidizer and abrasive, manufacturing conditions, and in the case of two-component developer, particle size distribution of carrier particles and Although selection of materials such as resistance and selection of coating agent and improvement of combination have been made, the present situation is that satisfactory results are not always obtained.

[0010]

As described above, although the nigrosine dye is a relatively excellent charge control agent, it also has various problems. These problems are solved, the chargeability is sufficiently high, the temperature and humidity dependence during development is low, the toner properties are not deteriorated by heat stress before use, the dispersibility in the binder resin is good, and the development properties are good. There is a demand for a charge control agent which is excellent in durability and durability and a positively chargeable toner containing the same.

An object of the present invention is to provide a toner for developing an electrostatic image which solves the above problems. That is, the object of the present invention is that the triboelectric charge amount of the toner is high and stable,
An object of the present invention is to provide an electrostatic charge image developing toner that does not cause a phenomenon such as an increase in fog or a decrease in image density.

Another object of the present invention is to provide a toner for developing an electrostatic charge image, in which the triboelectric charge amount of the toner is stable without being affected by changes in temperature and humidity, and the phenomena such as fog increase and image density decrease do not occur. To provide.

It is another object of the present invention to provide a toner for developing an electrostatic charge image which does not cause a phenomenon such as an increase in fog or a decrease in image density when used repeatedly and continuously by a copying machine or printer. It is in.

Another object of the present invention is to prevent fog from increasing even when the toner undergoes aging due to being left in a high temperature environment.
There is no decrease in the transfer rate and no scattering within the machine.
An object of the present invention is to provide an excellent electrostatic charge image developing toner having durability and stability.

A further object of the present invention is that the nigrosine dye is uniformly dispersed or compatible with the binder resin, and when the toner is made into a toner, the nigrosine dye is not dispersed or poorly distributed in the binder resin, and the toner is Is to provide an electrostatic charge image developing toner that is uniformly and positively charged.

The inventors of the present invention have stabilized the charging characteristics of the toner, improved the stability of the development characteristics, made permanent measures against the change of the toner over time, and exhibited good dispersibility and dispersibility in the binder resin for the nigrosine dye. As a result of earnest studies for obtaining the above, a toner containing a Nigrosine dye having a Fe content of 1.0% by weight or less as a charge control agent was found to solve the above problems, and the present invention was achieved. It is a thing.

[0017]

Specifically, the present invention relates to the following inventions (1) to (7). (1) In a toner for developing an electrostatic charge image containing at least a binder resin, a colorant and a nigrosine dye, the nigrosine dye undergoes a base treatment by adding aniline, water and sodium hydroxide to crude nigrosine, and occurs at that time. Fe content removed by centrifuging iron hydroxide is 1.0 wt%
A toner for developing an electrostatic charge image, comprising the following nigrosine dye. (2) The toner for developing an electrostatic charge image according to (1), wherein the toner is a magnetic toner. (3) The toner for developing an electrostatic charge image according to (1), wherein the toner is a non-magnetic toner. (4) The content of the nigrosine dye is 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin, for developing an electrostatic image according to any one of (1) to (3). toner. (5) The volume average particle size of the nigrosine dye is 1 to 20 μm.
The toner for developing an electrostatic charge image according to any one of (1) to (4), wherein the toner is m. (6) The toner for developing an electrostatic charge image according to any one of (1) to (5), wherein the hydrophobized inorganic fine powder is externally added as a fluidizing agent. (7) The toner for developing an electrostatic charge image according to any one of (1) to (6), wherein the toner has a positive charging property.

[0018]

The present invention will be described in more detail below. The nigrosine dye of the present invention is produced, for example, by the following method. Aniline and aniline hydrochloride are used as raw materials in the presence of ferric chloride with nitrobenzene at 160 to 180 ° C.
Crude nigrosine is obtained by oxidation and reaction with. The Fe content at this time is about 4 to 6% when calculated from the residue. By adding aniline, water and sodium hydroxide to this crude nigrosine, nigrosine is subjected to a base treatment, iron chloride is dissolved and precipitated as iron hydroxide (Fe (OH) _n ) and sodium chloride is generated. At this time, sodium chloride is dissolved in the aqueous phase. By removing these iron hydroxides using a centrifugal separator such as a screw decanter or a sharp press, the amount of Fe in the dried nigrosine dye can be reduced and adjusted. Sodium chloride in the aqueous phase can be removed by separating the aqueous phase.
Finally, the nigrosine dye may be finely pulverized to a desired particle size using a pulverizer such as a jet mill.

Fe content in the nigrosine dye is 1.0%
It is important that: When the Fe content is more than 1.0%, the conductivity of the nigrosine dye becomes high, and the charge retention ability decreases. When the charge retention ability is reduced, the original function as a charge control agent is reduced, which reduces the charge amount as toner,
Problems such as an increase in fog, a decrease in image density, and scattering in the machine will occur.

Further, most of the remaining Fe component exists in the state of iron hydroxide, which makes the nigrosine dye extremely unstable. This is iron hydroxide is Fe
Fe remains in the state of (OH) ₂ and Fe (OH) _3.
(OH) ₂ is easily oxidized when exposed to air, and the dried one gradually generates hydrogen and changes to Fe ₃ O ₄ . Further, Fe (OH) ₃ is positively charged, but as it is dehydrated, it is oxidized and changed to Fe ₂ O ₃ , which weakens the polarity. As described above, the nigrosine dye is easily affected by moisture and air due to the residual iron hydroxide, and the chargeability of the dye changes. It is this Fe (OH) ₂ that deteriorates in quality due to aging when left in a high temperature environment.
It is speculated that this is largely due to the fact that the oxidation of the remaining Fe (OH) ₃ and Fe (OH) ₃ is accelerated by high temperature.

Further, the presence of iron hydroxide in the nigrosine dye makes it difficult to uniformly distribute it in the binder resin. This is because iron hydroxide in the nigrosine dye is present in a granular form, and the particles serve as nuclei to facilitate aggregation. Therefore, it becomes difficult to uniformly disperse and distribute the nigrosine dye in the binder resin. Particularly, when the Fe content in the nigrosine dye is more than 1.0% by weight, the amount of particles increases, and the dispersibility of nigrosine in the toner is impaired. In this case, there is a difference in the nigrosine content between the toner mother particles obtained by classification and fine powder finer than that (hereinafter referred to as classification fine powder), resulting in unevenness. Furthermore, it becomes difficult to control the content of the charge control agent even when the classified fine powder is recycled as a raw material again.

From these facts, Fe in the nigrosine dye
By setting the content to 1.0% by weight or less, the nigrosine dye can be stabilized, its resistance can be adjusted, and the aggregate in nigrosine can be removed. As a result, the toner can have good image characteristics, stability over time, and dispersibility for recycling.

The Fe content in the nigrosine dye is
You can easily find the residue by
It Among the raw materials used in the synthesis of nigrosine dye
Iron remains as the only component remaining after combustion
Is. That is, it is possible to obtain the Fe content from the residual rate.
it can. At this time, the residue is Fe₂O₃Because this
More Fe₂O₃To calculate the Fe content
it can. This is Fe (OH) in nigrosine₂In the air
Touch Fe₃ O_FourAfter changing to
Finally Fe₂O₃Becoming Fe (OH)₃Is
Fe when dehydrated ₂O₃Because it is guided by
is there. For example, about 5g of Nigrosine dye sample in a crucible
Weigh it, set the electric furnace to 800 ℃, and leave it in the air for about 2 hours.
Leave it to burn completely and measure the weight of the residue after cooling.
By doing so, the residual rate [%] is obtained. Then left
What is obtained is Fe₂O₃So this is F
It is sufficient to calculate the content by converting it into e. Fe₂O ₃Molecule
The amount is 159.7, of which the atomic weight of Fe is 55.85.
Therefore, Fe ₂Has an atomic weight of 111.7.
From this Fe₂O₃The ratio of Fe in it is 69.9%
It 69.9% of the residue rate becomes the Fe content.

The particle size of the nigrosine dye in the electrostatic image developing toner of the present invention is preferably 1 to 20 μm in terms of volume average particle size. With this particle size, dispersion and distribution in the binder resin can be improved. As a result, uneven distribution of the charge control agent in the toner does not occur, and the toner can hold a uniform and stable charge. Volume average particle size is 20
If it exceeds μm, it becomes difficult to perform good dispersion / distribution in the binder resin. That is, the content of nigrosine in the classified fine powder becomes larger than that in the toner mother particles, and it becomes impossible to maintain a constant content of nigrosine when recycled and used again as a raw material. On the other hand, if it is smaller than 1 μm, the specific surface area of the nigrosine dye becomes large, which causes an excessive increase in the charge amount of the toner, resulting in a decrease in image density and a thick layer on the developer carrying member. There may be problems such as the generation of wave patterns.

The content of nigrosine in the toner can be quantified by absorbance analysis (wavelength: 567 nm).
A standard curve with a known amount of nigrosine dissolved in chloroform can be used to create a calibration curve to determine the nigrosine content of the unknown sample. By determining the content of the nigrosine in the toner mother particles, the classified fine powder, and the toner chip before fine pulverization by this quantitative analysis, the distributability of the nigrosine dye into the toner can be quantified. It can be seen that the dispersibility is good if there is almost no difference in the amount of nigrosine among the toner mother particles, the classified fine powder and the toner chips. On the other hand, it can be confirmed that when the difference in the content of nigrosine between the toner mother particles and the classified fine powder is large, poor distribution occurs.

The method of adding the nigrosine dye in the present invention to the toner includes a method of adding it inside the toner mother particles and a method of adding it externally. The method of adding to the inside of the toner mother particles is a general and preferable method.

The amount of nigrosine dye used in the toner is
It is determined according to the intended performance of the toner, and is not uniquely limited, but is used in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin,
5.0 parts by weight is preferable for maintaining excellent chargeability.

In the present invention, in combination with the nigrosine dye, any of those conventionally used as a charge control agent can be used as an auxiliary agent. In the present invention, a positive charge control agent is mainly used, and a fatty acid metal derivative, a triphenylmethane dye, a quaternary ammonium salt (for example, tributylbenzylammonium-1-hydroxy-4-naphthosulfone) is used in combination with a nigrosine dye. Acid salt, tetrabutylbenzyl ammonium tetrafluoroborate), diorganotin oxide (eg, dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide), diorganotin borate (dibutyltin borate, dioctyltin borate, dicyclohexyltin borate), etc. be able to.

As the colorant used in the present invention, it is possible to use any of the dyes and pigments conventionally used as colorants for toners. Examples of such known dyes and pigments include carbon black, lamp black, iron black, ultramarine blue, aniline blue (C.I. No. 50405), calconyl blue (C.I. No. Acess Blue3), Chrome Yellow (CI No. 14090), Ultramarine Blue (CI No. 77103), Methylene Blue Chloride (CI No 52015), Phthalocyanine Blue (CI No. 74160), DuPont Oil Red. (C.I. No. 26015), quinoline yellow (C.I. No. 47005), malachite green oxalate (C.I. No. 4200), lamp black (C.I. No. 77266), rose. Dyes or pigments such as Bengal (C.I. 45435) and mixtures thereof. . These colorants are usually added in an amount of 0.1 to 20 parts by weight, preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the binder resin.

When the electrostatic image developing toner of the present invention is used as a magnetic toner, magnetic materials that can be used include iron oxides such as magnetite, maghemite, and ferrite, or compounds of divalent metal and iron oxide, iron, cobalt, Metals such as nickel or aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium of these metals,
Examples thereof include powders of alloys of metals such as manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof. These magnetic materials have an average particle size of 0.05 to 2.0.
μm, preferably 0.1 to 0.5 μm, and the amount of the binder resin 1 contained in the magnetic toner is 1 μm.
5 to 150 parts by weight, preferably 10 to 100 parts by weight
~ 120 parts by weight. If necessary, a magnetic material and a colorant may be used in combination. As a colorant,
For example, carbon black, copper phthalocyanine, iron black, etc. are used.

Specific examples of the binder resin used in the toner of the present invention include styrene polymers such as polystyrene, poly-p-chlorostyrene, and homopolymers of substituted styrenes such as polyvinyltoluene. Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic copolymer, styrene-α-chloromethacrylic acid methyl ester Copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl ethyl ether copolymer, styrene-
Vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene diethylaminoethyl acrylate copolymer, styrene- Styrene-based copolymers such as butyl acrylate-diethylaminoethyl methacrylate copolymer, cross-linked styrene-based copolymers, etc .; polyester resins such as aliphatic dicarboxylic acids, aromatic dicarboxylic acids, aromatic dialcohols, diphenols Polyester resin having a monomer selected from the structural units as a structural unit, cross-linked polyester resin, etc .; other polyvinyl chloride, phenol resin, modified phenol resin, malein resin, rosin modified maleic resin, polyvinyl acetate Silicone resins, polyurethane resins, polyamide resins, epoxy resins, polyvinyl butyral, rosin, modified rosin, terpene resin, xylene resin, aliphatic or aliphatic hydrocarbon resins, and petroleum resins.

Examples of the acrylic monomer used in the styrene acrylic copolymer include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate,
(Meth) such as butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, etc.
Acrylic acid esters can be mentioned, and further, as a monomer that can be used together with them, maleic acid half esters such as acrylonitrile, methacrylonitrile, acrylamide, maleic acid, and butyl maleate, or diesters, vinyl acetate, chloride. Examples thereof include vinyl ethers such as vinyl, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone.

As the cross-linking agent used for producing the above-mentioned cross-linked styrenic polymer, a compound mainly having two or more unsaturated bonds can be mentioned, and specific examples thereof include divinylbenzene and divinyl. Aromatic divinyl compounds such as naphthalene; Carboxylic esters having two or more unsaturated bonds such as ethylene glycol diacrylate and ethylene glycol dimethacrylate; Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and unsaturated A compound having three or more bonds can be used alone or in a mixture. The cross-linking agent is used in an amount of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on 100 parts by weight of the binder resin.

These resins can be used alone or in combination of two or more kinds. Of these resins, styrene polymers and polyester resins are preferable because they exhibit particularly excellent charging characteristics. The molecular weight distribution measured by GPC (gel permeation chromatography) has at least one peak in the region of 1x10 ³ to 5x10 ⁴ and at least one peak or shoulder in the region of 10 ⁵ or more. Such a molecular weight can be obtained by using a styrene-based copolymer that has the above-mentioned styrene-based copolymer, further two or more kinds of resins, for example, a combination of the styrene resin and a styrene-acryl-based copolymer, or a combination of two or more kinds of the styrene-acryl-based copolymer. A resin composition having a distribution is preferable from the viewpoint of toner pulverizability and fixing property.

Further, when the pressure fixing method is used, a binder resin for pressure toner can be used. Examples of such resins include polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin and other waxes.

To the toner of the present invention, an additive such as a release agent which is conventionally used in the production of toner can be added as long as it does not have a substantial adverse effect. As the releasing agent, for example, an aliphatic hydrocarbon that improves the releasing property (offset prevention property) at the time of heat roll fixing,
Examples thereof include fatty acid metal salts, higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, and various waxes. Among these, the weight average molecular weight is 1
000 to 10,000, low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax,
Waxes such as carnauba wax, sazol wax and paraffin wax are preferred. These are usually 0.5-
It is added to the toner in an amount of about 5% by weight.

As the external additive used in the toner of the present invention, a fluidizing agent, an abrasive, a conductivity-imparting agent, a lubricant and the like can be used. As the base material of the fluidizing agent used in the present invention, for example, fine powder of silica, alumina, titania, magnesia, amorphous silicon-aluminum co-oxide, amorphous silicon-titanium co-oxide, etc. is used. You can Further, the fluidizing agent as an external additive has not only the purpose of imparting fluidity to the toner, but also the role of imparting and controlling the charging property of the toner. That is, the external additive adheres to the outermost surface of the toner, and thus has a great influence on the charging property of the toner.

The particles used as the fluidizing agent can be used as they are without surface treatment.
In some cases, environmental stability may be impaired due to hygroscopicity, and the fluidizing agent may adhere to the surface of the photoconductor drum to cause filming, resulting in image defects. Regarding the problem that the environmental stability due to hygroscopicity is impaired, in a high humidity environment, the fluidizing agent is affected by water, causing charge decay of the toner, causing fog on the image, and causing the toner to fly inside the machine. Will be. Therefore, the surface treatment of the particles used for the fluidizing agent is performed,
It is preferably hydrophobic. Further, by selecting a treating agent used for the surface treatment, it is possible to adjust and control the chargeability of the toner by making it have desired polarities of positive polarity and negative polarity, and stabilize the toner. It is necessary to select the surface treatment agent to be used. Examples of the surface treatment agent for the fluidizing agent used in the present invention include organoalkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane, dimethyldichlorosilane, trimethylchlorosilane, octadecyltrichlorosilane, and organochlorosilanes such as t-butyldimethylchlorosilane. , Silazanes such as hexamethyldisilazane, organoaminosilanes such as bis (dimethylamino) dimethylsilane, and silicone oil compounds can be used.

As the silicone oil type compound, straight silicone oil such as dimethyl silicone oil, methylphenyl silicone oil and methyl hydrogen silicone oil, or modified silicone oil can be used. The modifying group used in the modified silicone oil includes a methylstyrene group, a long-chain alkyl group, a polyether group, a carbinol group, an amino group, an epoxy group,
Examples thereof include a carboxyl group, a higher fatty acid group, a mercapto group and a methacryl group. Silicone oil has excellent releasability and slidability, and thus has the effect of preventing toner components from adhering to the surface of the photosensitive drum and filming.

As the external additives other than the fluidizing agent used in the present invention, the following publicly known lubricants, abrasives, conductivity-imparting agents and the like can be used. Examples of lubricants include polytetrafluoroethylene and zinc stearate,
Examples of the abrasive include fine powders of strontium titanate, calcium titanate, barium titanate, calcium carbonate, chromium oxide, silicon carbide, tungsten carbide, silicon nitride and the like. These abrasives have the effect of removing the toner component deposits and filming substances on the surface of the photoconductor drum by polishing and shaving them, and are used together with the fluidizing agent surface-treated with the silicone oil. Therefore, a great effect can be found. A metal oxide such as tin oxide may be added as the conductivity-imparting agent. However, these examples are merely examples, and what is added and mixed in the electrophotographic developer of the present invention is not limited to those specifically exemplified above.

The toner mother particles used in the present invention are prepared by premixing the above-mentioned toner constituents with a dry blender, a Henschel mixer, a ball mill, etc., and thereafter, this mixture is heated roll, kneader, uniaxial or biaxial extruded. It is preferable that the kneaded product is melt-kneaded by a heat kneader such as a ruder, the obtained kneaded product is cooled, pulverized, and, if necessary, classified into a desired particle size. However, the manufacturing method of the toner mother particles used in the present invention is not limited to this kneading and pulverizing method, for example, a method of dispersing the toner constituent material in the binder resin solution, and then spray drying,
Alternatively, any of conventionally known methods such as a method of obtaining a toner mother particle by polymerizing an emulsion suspension by mixing a predetermined material with a monomer that constitutes the binder resin may be used. Of course. The volume average particle diameter of the toner base particles used in the present invention is preferably 3 to 35 μm, more preferably 5 to 25 μm. In the case of small-sized toner mother particles, the particle size is about 4 to 15 μm.

In order to finally manufacture a toner, it is necessary to add and mix an external additive to the toner mother particles obtained above. Generally, an external additive is added to the toner mother particles and mixed using a Henschel mixer, a super mixer or the like. Even in this mixing step, the quality and characteristics of the toner greatly change depending on the process conditions. The controllable factors in this mixing process include the amount of filling in the mixer, the number of revolutions,
Examples include mixing time. Since the mixing conditions of the toner base particles and the external additive have a great influence on the adhesion state of the external additive on the surface of the toner base particles, it is preferable to appropriately adjust the mixing conditions.

As a final step after adding and mixing the external additive, the toner is manufactured through a sieving step for the purpose of removing foreign matters in the toner. As the type of sieve, a vibration sieving machine, an ultrasonic vibration sieving machine, a gyro shifter, or the like can be used.
At that time, since the mesh size and type of the mesh used for the sieve affect the quality of the toner, it is preferable to adjust the conditions appropriately.

The toner for developing an electrostatic image of the present invention can be used as a two-component developer together with a carrier. The carrier used with the toner of the present invention may be any conventionally used carrier, for example, ferromagnetic metal such as iron powder or alloy powder of ferromagnetic metal, nickel, copper, zinc, magnesium, barium, etc. Ferrite powder, magnetite powder and the like composed of elements are preferred. These carriers are styrene / acrylic copolymer, styrene / methacrylate copolymer,
It may be coated with a resin such as a styrene polymer, a silicone resin, a fluorine-containing resin or a mixture thereof. As a method of coating the carrier with a resin, a resin for coating is dissolved in a solvent, and this is coated on the core particles by a dipping method, a spray method, a fluidized bed method, etc., dried and then heated if necessary. Any known method such as a method of curing the film can be used. The average particle size of carrier particles is usually 1
Those having a thickness of 5 to 500 μm, preferably 20 to 300 μm can be used.

[0045]

EXAMPLES The present invention will be described in more detail with reference to production examples, examples and comparative examples, but the embodiments of the present invention are not limited to these examples. In the following, all parts are parts by weight.

[Production Example of Nigrosine Dye] 160 with nitrobenzene in the presence of aniline, hydrochloric acid and ferric chloride.
Oxidation and reaction were carried out at ˜180 ° C. to obtain crude nigrosine (this crude nigrosine contains the residue of ferric chloride).
Then, aniline, water and sodium hydroxide were added to the crude nigrosine, and the precipitates of nigrosine and iron hydroxide were separated by centrifugal separation with a screw decanter to remove the iron hydroxide precipitate. The obtained liquid is further washed with water and the liquid is dried,
Nigrosine dye was obtained by crushing. The Nigrosine dyes obtained are summarized in Table 1. The Fe content was adjusted by centrifuging conditions, and the volume average particle size was adjusted by changing pulverization conditions.

[0047]

[Table 1]

[Example 1] (Component) (Blending amount) Styrene acrylic copolymer 100 parts Magnetic material (magnetite) 70 parts Low molecular weight polypropylene 2.5 parts Nigrosine dye (A) (particle size 6.1 μm) 2. 5 parts After uniformly mixing the above materials, kneading was performed to obtain chips, and the chips were crushed and classified to obtain positively chargeable toner mother particles having an average particle size of 10.5 μm. Next, the toner mother particles 1
0.3 parts of silica fine powder treated with dimethyldichlorosilane and 0.5 part of tungsten carbide fine powder were added to and mixed with 00 parts of the mixture to obtain a positively chargeable magnetic toner.
Using this toner, a commercially available copying machine NP-3050 (manufactured by Canon Inc.) was used at room temperature and normal humidity (23 ° C., 50% RH),
High temperature and high humidity (30 ℃, 85% RH), low temperature and low humidity (10 ℃,
The actual shooting test was performed under the environment of 20% RH. In any of the environments, a good solid black image without fog was obtained from the initial stage of development. Further, while replenishing the toner, the image output of 10,000 sheets was evaluated, and as with the initial image, a good image without problems could be obtained. Further, the contents of the nigrosine dye in the toner mother particles and the toner fine powder particles obtained by classification were measured. The measurement results are summarized in Table 2. There was almost no difference in the content of the nigrosine dye in the toner mother particles and the classified fine powder, and the distributability of the nigrosine dye was excellent.

[0049]

[Table 2]

[Example 2] Instead of the nigrosine dye (A) used in Example 1, a nigrosine dye (B) (particle size 7.
A positively chargeable magnetic toner was obtained in the same manner as in Example 1 except that 2 μm) was used. Using this toner, a commercially available copying machine NP-3050 (manufactured by Canon Inc.) was used at room temperature and normal humidity (2
3 ℃, 50% RH, high temperature and high humidity (30 ℃, 85% R)
H), a low temperature and low humidity (10 ° C., 20% RH) environment. In any of the environments, a good solid black image without fog was obtained from the initial stage of development. Further, while replenishing the toner, the image output of 10,000 sheets was evaluated, and as with the initial image, a good image without problems could be obtained. Further, there was almost no difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder, and the distributability of the nigrosine dye was excellent.

Comparative Example 1 The nigrosine dye (A) used in Example 1 was replaced with the nigrosine dye (C) (particle size 8.9 μm).
A positively chargeable magnetic toner was obtained in the same manner as in Example 1 except that Using this toner, a real-image copying test was conducted in the same manner as in Example 1. As a result, room temperature and normal humidity (23 ° C., 50%
Under the condition of RH, high temperature and high humidity (3
The image density decreased after passing over 1,000 sheets at 0 ° C. and 85% RH. Further, there was a difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder.

Comparative Example 2 The nigrosine dye (A) used in Example 1 was replaced with the nigrosine dye (D) (particle size 9.1 μm).
A positively chargeable magnetic toner was obtained in the same manner as in Example 1 except that Using this positively chargeable magnetic toner, the same real-image test as in Example 1 was conducted.
At around 3 ° C and 50% RH)
Under high temperature and high humidity (30 ° C., 85% RH), after about 500 sheets, the image density decreased. Further, there was a difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder.

[Example 3] (Component) (Blending amount) Styrene acrylic copolymer 100 parts Carbon black 9 parts Low molecular weight polypropylene 5 parts Nigrosine dye (A) 2 parts The above materials are uniformly mixed and then kneaded into chips. Then, the chips were pulverized and classified to obtain positively chargeable toner mother particles having an average particle size of 11.7 μm. Next, the toner mother particles 1
0.3 parts of positively chargeable hydrophobic silica fine powder to 00 parts,
And 0.5 parts of tungsten carbide fine powder,
By mixing, a positively chargeable non-magnetic toner was obtained. 6 parts of the obtained toner and 100 parts of a carrier coated with a silicone resin having an average particle diameter of 60 μm were mixed using a ball mill to prepare a developer. Next, using the toner and the developer, a commercial copying machine Rheo Dry 4550 (manufactured by Toshiba Corp.) was used to perform an actual copying test in an environment of normal temperature and normal humidity (23 ° C., 50% RH). At this time, the toner was heated in a dryer at 50 ° C. for 72 hours in order to facilitate confirmation of changes with time.
When the obtained toner and developer were used, fog was small even after 10,000 sheets were actually photographed, the image density was stable, and toner scattering in the machine was not observed. Further, there was almost no difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder, and the distributability of the nigrosine dye was excellent.

Example 4 A positively chargeable non-magnetic toner and a developer are obtained in the same manner as in Example 3 except that the nigrosine dye (A) used in Example 3 is replaced with the nigrosine dye (B). It was Using this toner and developer, the same actual copying test as in Example 3 was conducted. At this time, the toner was dried in a dryer at 50 ° C. for 7 days in order to facilitate confirmation of change over time.
It heated under the condition of 2 hours. When the obtained toner and developer were used, fog was small even after 10,000 actual copies,
The image density was stable, and no toner was scattered inside the machine. Further, there was almost no difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder, and the distributability of the nigrosine dye was excellent.

[0055] A quaternary ammonium salt was added to the material used in Example 3 in combination, and a positively chargeable non-magnetic toner and a developer were obtained in the same manner as in Example 3. Using this toner and developer, the same actual copying test as in Example 3 was conducted. At this time, the toner is placed in a drier in order to facilitate confirmation of the change over time and identify it.
The mixture was heated under the conditions of ° C and 72 hours. When the obtained toner and developer were used, fog was small even after 10,000 sheets were actually photographed, the image density was stable, and toner scattering in the machine was not observed. Further, there was almost no difference in the content of the nigrosine dye in the toner mother particles and the toner fine powder particles obtained by classification, and the dispersibility of the nigrosine dye was excellent.

Comparative Example 3 A positively chargeable non-magnetic toner and a developer were prepared in the same manner as in Example 3 except that the nigrosine dye (A) used in Example 3 was replaced with the nigrosine dye (C). Obtained. Using this toner and developer, the same actual copying test as in Example 3 was conducted. At this time, the toner is placed in a drier in order to facilitate confirmation of the change over time and identify it.
The mixture was heated under the conditions of ° C and 72 hours. When the obtained toner and developer were used, normal temperature and humidity (23 ° C, 50% R
Under H), it was as good as in Example 3 until after 2,000 actual copies, but after that, fog increased and toner scattering inside the machine became noticeable. The test was stopped after 3000 sheets were printed. Also,
There was a difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder.

Comparative Example 4 A positively chargeable non-magnetic toner and a developer were prepared in the same manner as in Example 3 except that the nigrosine dye (A) used in Example 3 was replaced with the nigrosine dye (D). Obtained. Using this toner and developer, the same actual copying test as in Example 3 was conducted. At this time, the toner is placed in a drier in order to facilitate confirmation of the change over time and identify it.
The mixture was heated under the conditions of ° C and 72 hours. When the obtained toner and developer were used, normal temperature and humidity (23 ° C, 50% R
Under H), there was a lot of fog from the beginning and scattering was seen inside the aircraft. Further, there was a difference in the content of the nigrosine dye in the toner mother particles obtained by classification and the classified fine powder.

[0058]

EFFECT OF THE INVENTION By using a nigrosine dye having a specific composition, the toner has a high triboelectric charge amount and is stable, and further, the fog is increased and the image density is lowered without being affected by changes in temperature and humidity. An excellent electrostatic image developing toner in which no phenomenon occurs is obtained.

Furthermore, when repeatedly continuously copying with a copying machine or printer, fog does not increase, image density decreases, and toner components do not adhere to the surface of the photoconductor.
Even if it is subjected to aging due to being left at high temperature, fog does not increase, the transfer rate of toner does not decrease, and it does not scatter in the copying machine or printer. Excellent durability and stability. An image developing toner was obtained.

Further, the nigrosine dye is uniformly dispersed or compatible in the binder resin, and when the toner is formed into a toner, the distribution failure of nigrosine is not caused, and the toner is uniformly and positively charged. Got

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-102269 (JP, A) JP-A-9-87535 (JP, A) JP-A-6-230611 (JP, A) JP-A-1- 219848 (JP, A) JP 52-135336 (JP, A) JP 60-118851 (JP, A) JP 59-200258 (JP, A) JP 2001-11055 (JP, A) (JP 58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08-9/097

Claims (7)

(57) [Claims] 1. At least a binder resin, a colorant, and a negro.
In the toner for developing electrostatic images containing a thin dye, two
Grosine dye is used to convert crude nigrosine to aniline, water, and hydroxy.
Base treatment by adding sodium chloride, which occurs at that time
The Fe content of the iron hydroxide removed by centrifugation is 1.
A toner for developing an electrostatic charge image , which comprises 0% by weight or less of a nigrosine dye . 2. The toner for developing an electrostatic charge image according to claim 1, wherein the toner is a magnetic toner. 3. The toner for developing an electrostatic charge image according to claim 1, wherein the toner is a non-magnetic toner. 4. The content of the nigrosine dye is equal to that of the binder resin 1.
The toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the amount is 0.1 to 10 parts by weight with respect to 00 parts by weight. 5. The volume average particle diameter of the nigrosine dye is 1
The toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the toner has a particle size of -20 μm. 6. The toner for developing an electrostatic charge image according to claim 1, wherein the hydrophobically treated inorganic fine powder is externally added as a fluidizing agent. 7. The toner for developing an electrostatic charge image according to claim 1, wherein the toner has a positive charging property.