JP2002318466A - Electrostatic latent image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing toner having uniform distribution of the charge amount, showing stable electrification characteristics without decreasing the triboelectrification charge amount and without performing a charge-up, and having excellent fluidity, environmental dependence and durability characteristics. SOLUTION: Both of anatase titanium oxide having from 10 to <200 nm average particle size and rutile titanium oxide having from 200 to <500 nm average particle size are externally added to the toner particles to prepare the electrostatic latent image developing toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic method, an electrostatic recording method,
The present invention relates to an electrostatic latent image developing toner used in a developing process such as an electrostatic printing method.

[0002]

2. Description of the Related Art In dry electrophotography, toner particles used for converting an electrostatic latent image into a visible image generally include a thermoplastic binder resin (binder resin), a charge control agent, and magnetic particles. After preliminary mixing with the additives, the mixture is subjected to melt-kneading, pulverizing, and classifying steps to produce toner particles having a desired particle diameter. In the toner particles, a certain amount of positive or negative charge is accumulated on the particle surface by frictional charging, and the charged particles are used for developing an electrostatic latent image.
Here, it is necessary that the electric charge accumulated on the toner particle surface due to the triboelectric charging be either positive or negative depending on the type of photoconductive photoconductor used for forming the electrostatic latent image. In this case, the amount of charge needs to be sufficient to more accurately visualize the electrostatic latent image. For this reason, it is common to mix and disperse a charge controlling agent or a conductive substance in a binder resin to control the charge and the amount of charge on the surface of the toner particles, and to control inorganic fine particles such as silica, aluminum oxide, titanium oxide and zinc oxide. Powder is generally added. However, these inorganic fine powders
Because it is generally hydrophilic, depending on environmental conditions such as humidity,
There has been a problem that the charging characteristics of the toner particles are likely to change greatly.

In order to prevent the influence of such environmental conditions, the surface of these inorganic fine powders is treated with a hydrophobizing agent or a polar group is introduced.

For example, Japanese Patent Application Laid-Open No. 52-135739 proposes a technique using a metal oxide surface-treated with an aminosilane coupling agent to introduce a polar group. Japanese Patent Application Laid-Open No. 10-3177 proposes to use a titanium compound treated with a silane coupling agent. In addition, Japanese Patent Application Laid-Open No. 5-181306
Japanese Patent Application Laid-Open No. H11-163873 proposes an electrostatic latent image developer in which abrasive particles such as alumina and zirconia are fixed to the surface of toner base particles and the ratio of the particle diameter of the toner base particles to the particle size of the abrasive particles is controlled. Have been. According to these electrostatic latent image developers, an excellent polishing effect can be obtained on the surface of the photoconductor, and there is no need to incorporate a large system such as a cleaning brush.
The apparatus can be reduced in size, and is effective against image deletion, image density, fog, and the like. However, Japanese Patent Application Laid-Open No. 52-135
In the developer disclosed in Japanese Patent No. 739, since the aminosilane coupling agent is hydrophilic, there has been a problem that the fluidity and charging characteristics of the toner are significantly reduced in a high-temperature and high-humidity environment. Further, the titanium compound disclosed in Japanese Patent Application Laid-Open No. 10-3177 has a problem that it causes extreme charge-up, makes the charge amount distribution non-uniform, and causes problems such as a decrease in image density and fog. . Furthermore, the electrostatic latent image developer disclosed in Japanese Patent Application Laid-Open No. 5-181306 can exert a predetermined polishing ability on the surface of the photoreceptor, but has unstable charging characteristics, The durability characteristics of the toner were not always satisfactory.

Further, Japanese Patent Application Laid-Open No. 62-113158,
JP-A-64-62667 and JP-A-5-18
No. 8633 discloses a toner to which hydrophobic silica and titanium oxide (anatase type) are externally added.
However, such a toner has a problem that the titanium oxide (anatase type) is buried in the toner due to friction and the charging characteristics become unstable.

Therefore, Japanese Patent Application Laid-Open No. 2000-128534 discloses a hydrophobic oxidizing treatment in which the surface of a rutile type titanium oxide partially containing hydrous titanium oxide and / or anatase type titanium oxide is treated with a silane coupling agent. A toner using titanium as an external additive is disclosed. And the major axis diameter of the hydrophobic titanium oxide is 0.02 to 0.1 μm,
The axial ratio is set to 2 to 8 to prevent the toner from being embedded in the toner. However, such a hydrophobic titanium oxide is not easy to produce, and has a low bulk density,
There has been a problem that it is still difficult to exhibit stable charging characteristics.

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention
As a result of diligent studies of conventional problems, anatase-type titanium oxide having a predetermined average particle size is added in order to exert polishing power, and rutile-type oxidation having a predetermined average particle size is provided in order to sharpen the charge amount distribution. The present inventors have found that the addition of titanium makes it possible to solve the problem of the toner for developing an electrostatic latent image by superimposing them, thereby completing the present invention. That is, an object of the present invention is to provide a uniform charge amount distribution, exhibit a stable charge characteristic without lowering the triboelectric charge amount and without charging up, and have excellent fluidity, environmental dependency, and durability characteristics. And a method for manufacturing the same.

[0008]

According to the present invention, both an anatase-type titanium oxide having an average particle size of less than 10 to 200 nm and a rutile-type titanium oxide having an average particle size of less than 200 to 500 nm are used as toner particles. In response, an electrostatic latent image developing toner characterized by being subjected to an external addition process is provided,
The above-mentioned problem can be solved. That is, by the action of anatase type titanium oxide having a predetermined average particle diameter, it is possible to obtain a toner for developing an electrostatic latent image excellent in fluidity, environment dependency, and durability. In addition, due to the function of rutile type titanium oxide having a predetermined average particle diameter, the electrostatic charge distribution of the toner is uniform, and the electrostatic latent charge exhibits stable charging characteristics without reducing the triboelectric charge amount and without charging up. An image developing toner can be obtained.

Further, in constituting the toner for developing an electrostatic latent image of the present invention, the addition ratio of anatase type titanium oxide and rutile type titanium oxide is 10:90 to 90:
It is preferable to set the value in the range of 10. With this configuration, it is possible to effectively exhibit both functions of the anatase-type titanium oxide and the rutile-type titanium oxide to obtain a toner for developing an electrostatic latent image exhibiting excellent environment dependency and charging characteristics. Can be.

In constituting the toner for developing an electrostatic latent image of the present invention, the total addition amount of anatase-type titanium oxide and rutile-type titanium oxide is set to 0.1% with respect to toner particles.
It is preferable to set the value in the range of 5 to 5% by weight. With this configuration, it is possible to effectively exhibit both functions of the anatase-type titanium oxide and the rutile-type titanium oxide to obtain a toner for developing an electrostatic latent image exhibiting excellent environment dependency and charging characteristics. Can be.

When the toner for developing an electrostatic latent image of the present invention is used for an organic photoreceptor (OPC photoreceptor), the volume resistivity of anatase-type titanium oxide and rutile-type titanium oxide are respectively determined. 1 × 10 ⁴ -1 × 1
0 to a value within the range of ¹⁵ Omega · cm, when used in an amorphous silicon photosensitive member (a-Si photosensitive member), respectively 1 × 10 ¹ ~ anatase titanium oxide and rutile-type titanium oxide volume resistivity of It is preferable that the value be in the range of 1 × 10 ⁷ Ω · cm. With this configuration, regardless of whether the electrostatic latent image developing toner is used for the OPC photoconductor or the a-Si photoconductor, the anatase type titanium oxide and the rutile are used. It is possible to obtain a toner for developing an electrostatic latent image exhibiting excellent environmental dependency and charging characteristics by effectively exhibiting both functions of the titanium oxide.

In constituting the toner for developing an electrostatic latent image of the present invention, it is preferable that the rutile type titanium oxide and the anatase type titanium oxide are each surface-treated with a titanate coupling agent. As described above, since the titanium oxide is subjected to the hydrophobic treatment with the titanate-based coupling agent, it is possible to obtain a toner for developing an electrostatic latent image which is hardly affected by ambient humidity conditions.

In constituting the toner for developing an electrostatic latent image of the present invention, it is preferable that the toner is applied to a printer equipped with an organic photoreceptor (OPC photoreceptor). That is,
Since the toner for developing an electrostatic latent image of the present invention is excellent in both positive chargeability and negative chargeability, it is suitable for a printer equipped with an OPC photosensitive member, for example, an image forming apparatus 1 as shown in FIG. Can be used for More specifically, in the image forming apparatus 1, the developing device 10, the transfer roller 19, the cleaning blade 13, and the charging unit 8 are arranged around the amorphous silicon photoreceptor 9 rotating clockwise along the rotation direction. It is arranged. In the example of the image forming apparatus 1 as shown in FIG. 1, a developing roller 32 is provided in the developing device 10, and the surface of the developing roller 32 is separated from the surface of the amorphous silicon photoreceptor 9 by a predetermined distance. And the toner container 31
Thus, a predetermined amount of toner can be supplied as needed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention relates to an anatase type titanium oxide having an average particle diameter of 10 to less than 200 nm,
An electrostatic latent image developing toner characterized in that both of rutile titanium oxide having an average particle diameter of 200 to less than 500 nm are externally added to toner particles. Hereinafter, the toner particles and the external additive will be roughly described. 1. Toner Particles (1) Binder Resin Type 1 The type of binder resin used in the toner of the present invention is not particularly limited, and examples thereof include a styrene resin, an acrylic resin, a styrene-acryl copolymer, and a polyethylene resin. Use thermoplastic resin such as resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether resin, N-vinyl resin, and styrene-butadiene resin. Is preferred.

More specifically, the polystyrene resin may be a homopolymer of styrene or a copolymer with another copolymerizable monomer copolymerizable with styrene. Examples of such copolymerized monomers include p-chlorostyrene; vinylnaphthalene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; and vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dotesyl acrylate, n-octyl acrylate, acrylic acid (Meth) acrylates such as 2-chloroethyl, phenyl acrylate, α-methyl methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; and other acrylates such as acrylonitrile, methacrylonitrile, and acrylamide. Acrylic acid derivatives, vinyl methyl ether, vinyl ethers such as vinyl isobutyl ether; vinyl methyl ketone, vinyl ethyl ketone, vinyl ketones such as methyl isopropenyl ketone; N- vinyl pyrrole, N- vinyl carbazole, N- vinyl indole,
N-vinyl compounds such as N-vinylpyrrolidene are exemplified. These can be used alone and copolymerized with a styrene monomer, or two or more of them can be copolymerized with a styrene monomer.

As the polyester-based resin, any resin obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be suitably used.

Such alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-
Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5
-Pentanediol, 1,6-hexanediol, 1,
Diols such as 4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol;
Bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexane tetrol, 1,4-
Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,2 4-butanetriol, trimethylolethane, trimethylolpropane, 1,
3,5, -trihydroxymethylbenzene and the like are exemplified.

As the carboxylic acid component, divalent or trivalent carboxylic acids, acid anhydrides of these carboxylic acids, or lower alkyl esters of these carboxylic acids are used. More specifically, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n
Divalent carboxylic acids such as octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid); 2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-
Examples thereof include trivalent or higher carboxylic acids such as cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

Molecular Weight Distribution The binder resin preferably has at least two or more molecular weight distribution peaks (low molecular weight peak and high molecular weight peak) in the weight average molecular weight measured by gel permeation chromatography (GPC). Specifically, the low molecular weight peak is 3,000 to
Binder resins having a molecular weight in the range of 20,000 and another high molecular weight peak in the range of 3 × 10 ⁵ to 15 × 10 ⁵ are preferred. The reason is that when the low molecular weight peak is within the above range, the fixability of the toner for developing an electrostatic latent image is improved. Conversely, the low molecular weight peak is 3,
If the value is less than 000, an offset is likely to occur at the time of fixing, and the storage stability of the toner for developing an electrostatic latent image at a use environment temperature (5 to 50 ° C.) is reduced, which may cause caking. Because there is. On the other hand, when the high molecular weight peak is within the above range, the offset property of the toner for developing an electrostatic latent image is improved. Conversely, when the high molecular weight peak exceeds 20,000, the binder resin This is because the compatibility between the polymer and the charge control agent may decrease, and uniform dispersion may not be obtained. Therefore, fog, contamination of the photoreceptor, poor fixing and the like may easily occur.

Further, in the binder resin, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 10 or more. The reason for this is that if the ratio of Mw / Mn is less than 10,
This is because the fixing property and the offset property of the toner for developing an electrostatic latent image may deteriorate, and both characteristics may not be sufficiently satisfied.

Crosslinking Structure The binder resin is preferably a thermoplastic resin from the viewpoint of good fixability, but the amount of the crosslinking component (gel amount) measured using a Soxhlet extractor is 10% by weight or less.
More preferably, if the value is within the range of 0.1 to 10% by weight, the resin may be a curable resin. By introducing a partially crosslinked structure in this way, the storage stability, form retention, and durability of the toner can be further improved without lowering the fixing property. Therefore, it is not necessary to use 100% by weight of a thermoplastic resin as a binder resin of the toner, and it is preferable to add a cross-linking agent or partially use a thermosetting resin.

Examples of such thermosetting resins include epoxy resins and cyanate resins. More specifically, bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, novolak epoxy resins, One type of alkylene ether type epoxy resin, cycloaliphatic type epoxy resin, cyanate resin and the like may be used alone or in combination of two or more types.

Functional Group It is preferable that the binder resin has a functional group in order to improve the dispersibility of the magnetic particles. Examples of such a functional group include at least one selected from a hydrokoxy (hydroxyl) group, a carboxyl group, an amino group, and a glycidoxy (epoxy) group. Incidentally, whether the binder resin has these functional groups,
It can be confirmed using an FT-IR device, and the content of the functional group can be quantified using a titration method.

Glass Transition Point The glass transition point of the binder resin is preferably set to a value within the range of 55 to 70 ° C. The reason is that when the glass transition point of the binder resin is lower than 55 ° C.,
This is because the obtained toners for developing an electrostatic latent image may be fused to each other and storage stability may be reduced. On the other hand, when the glass transition point of the binder resin exceeds 70 ° C., the fixability of the toner may be poor. Therefore, the glass transition point of the binder resin is more preferably set to a value in the range of 58 to 68 ° C, and further preferably to a value in the range of 60 to 66 ° C.

The glass transition point of the binder resin is as follows:
Using a differential scanning calorimeter (DSC), it can be determined from the point of change in specific heat.

Softening Point When the binder resin is crystalline, its melting point (or softening point) is preferably set to a value within the range of 110 to 150 ° C. The reason is that if the melting point (or softening point) of the binder resin is lower than 110 ° C., the obtained toners may be fused to each other and storage stability may be reduced. On the other hand, if the melting point (or softening point) of the binder resin exceeds 150 ° C., the fixability of the toner may be significantly reduced. Therefore, the melting point (or softening point) of the binder resin is set to 115 to 145 ° C.
Is more preferably in the range of 120 to 14
More preferably, the value is in the range of 0 ° C. In addition,
The melting point (or softening point) of the binder resin is determined by a melting peak position measured using a differential scanning calorimeter (DSC),
It can be obtained from the falling ball method.

(2) Wax In the toner of the present invention, it is preferable to add a wax in order to improve the fixability and the offset property and to reduce the rejection rate of the reading device. here,
The type of wax to be added is not particularly limited, and examples thereof include polyethylene wax, polypropylene wax, Teflon (registered trademark) -based wax (fluorine-based wax), Fischer-Tropsch wax, paraffin wax, ester wax, and montan. It is preferable to use wax, rice wax or the like. Further, these waxes may be used in combination. By adding such a wax, the offset property can be improved, and image smearing can be more efficiently prevented. The Fischer-Tropsch wax is a straight-chain hydrocarbon compound having a small number of iso-structure molecules and side chains, produced by utilizing the Fischer-Tropsch reaction, which is a catalytic hydrogenation reaction of carbon monoxide.

Further, among the Fischer-Tropsch waxes, the weight average molecular weight is a value of 1,000 or more,
Further, those having an endothermic bottom peak by DSC in the range of 100 to 120 ° C are more preferable. Examples of such a Fischer-Tropsch wax include Sasol wax C1 (high molecular weight grade obtained by crystallization of H1, endothermic bottom peak: 106.5) available from Sasol.
° C), Sasol wax C105 (refined product of C1 by a fractionation method, endothermic bottom peak: 102.1 ° C), Sasol wax SPRAY (fine particle product of C105, endothermic bottom peak: 102.1 ° C) and the like. .

The amount of the wax added is not particularly limited. For example, when the total amount of the toner for developing an electrostatic latent image is 100% by weight, the amount of the wax added is 1 to 100% by weight. It is preferred that the value be in the range of 5% by weight. The reason is that the amount of the wax added is 1% by weight.
When the amount is less than 5%, it may not be possible to efficiently prevent the offset property reduction and image smearing from occurring. On the other hand, when the added amount of the wax exceeds 5% by weight,
This is because the toner for developing an electrostatic latent image may be fused to each other and storage stability may be reduced.

(3) Charge Control Agent In the toner for developing an electrostatic latent image of the present invention, the charge level and the charge start-up characteristic (indicator of whether or not the charge is maintained at a constant charge level in a short time) are significantly improved, and It is preferable to add a charge control agent since characteristics excellent in stability and stability can be obtained. Here, the type of the charge control agent to be added is not particularly limited, and examples thereof include charge control agents having the following positive chargeability and negative chargeability.

Positively Chargeable Charge Control Agent Examples of the positively chargeable charge control agent include nigrosine, a quaternary ammonium salt compound, and a resin type charge control agent in which an amine compound is bonded to a resin. Specifically, pyridazine, pyrimidine, pyrazine as azine compounds,
Orthooxazine, methoxazine, paraoxazine,
Orthothiazine, metathiazine, parathiazine, 1,
2,3-triazine, 1,2,4-triazine, 1,
3,5-triazine, 1,2,4-oxadiazine,
1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5
-Tetrazine, 1,2,3,5-tetrazine, 1,2,
Azin Fast Red FC, Azin Fast Red 12BK, Azin Violet BO, Azin Violet 3G as direct dyes composed of 4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline, and azine compounds , Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW and Azin Deep Black 3R
L, nigrosine as a nigrosine compound, nigrosine salt, nigrosine derivative, nigrosine BK, nigrosine NB, nigrosine Z, metal salts of naphthenic acid or higher fatty acid, alkoxylated amine, alkylamide, quaternary as acidic dyes composed of the nigrosine compound As the ammonium salt, benzylmethylhexyldecylammonium, decyltrimethylammonium chloride and the like may be used alone or in combination of two or more. In particular,
The nigrosine compound is most suitable for a positively chargeable toner for developing an electrostatic latent image since a quicker rise can be obtained.

Further, a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, and the like are mentioned. More specifically, a polystyrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, carboxylic acid Polystyrene resin having a salt, acrylic resin having a carboxylate, styrene-acryl resin having a carboxylate, polyester resin having a carboxylate, polystyrene resin having a carboxyl group, acrylic having a carboxyl group Resins, styrene-acrylic resins having a carboxyl group, polyester resins having a carboxyl group, and the like, alone or in combination of two or more.
In particular, styrene-acrylic resins (styrene-acrylic copolymers) having a quaternary ammonium salt, carboxylate or carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. It is the best charge control agent because it can.

Negatively-chargeable charge control agents As those exhibiting negatively-chargeable properties, for example, organometallic complexes and chelate compounds are effective, and monoazo metal complexes,
There are acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

Addition amount When the total amount of the toner for developing an electrostatic latent image is defined as 100% by weight, the addition amount of the charge control agent is set to a value within the range of 1.5 to 15% by weight. preferable. The reason for this is that if the amount of the charge control agent is less than 1.5% by weight, it is difficult to stably impart charging characteristics to the toner for developing an electrostatic latent image, and the image density becomes low. This is because the durability may be reduced. In addition, dispersion failure is likely to occur, which may cause so-called fogging, or may cause severe photoconductor contamination. On the other hand, if the added amount of the charge control agent exceeds 15% by weight, environmental resistance, particularly poor charging and image failure under high temperature and high humidity, and defects such as photoreceptor contamination may easily occur. . Therefore, since the balance between the charge control function and the durability of the toner for developing an electrostatic latent image is better, the amount of the charge control agent to be added is within the range of 2.0 to 8.0% by weight. It is more preferable to set the value to 3.0 to 7.0.
More preferably, the value is in the range of 0% by weight.

(4) Type of Magnetic Particles In the toner for developing an electrostatic latent image, it is preferable to add magnetic particles in order to control charging characteristics. Examples of such magnetic particles include magnetic particles containing iron oxide (magnetite), iron powder, cobalt powder, nickel powder, and ferrite powder as main components, and iron oxide (magnetite) having ferromagnetism such as cobalt and nickel. Magnetic particles doped with the metals shown can be mentioned. Further, an alloy which does not contain a ferromagnetic element as it is but becomes ferromagnetic when subjected to an appropriate heat treatment, such as chromium dioxide, can be used as the magnetic particles.

The magnetic particles are preferably subjected to a surface treatment using a surface treatment agent such as a titanium-based coupling agent or a silane-based coupling agent. The reason for this is that by performing such a surface treatment, the affinity between the magnetic particles and the binder resin is improved, and the magnetic particles can be more uniformly dispersed in the binder resin. Further, since the magnetic particles are usually hydrophilic, by performing such a surface treatment, it is possible to appropriately make the particles hydrophobic, and as a result, it is possible to improve the moisture resistance of the toner. .

Average Particle Size The average particle size of the magnetic particles is preferably set to a value within the range of 0.1 to 0.5 μm. The reason for this is that if the average particle diameter of such magnetic particles is outside these ranges, it may be difficult to uniformly disperse and uniformly charge the toner particles. Therefore, the average particle diameter of the magnetic particles is more preferably set to a value in the range of 0.15 to 0.45 μm, and more preferably to a value in the range of 0.2 to 0.4 μm. preferable.

When the magnetic particles are applied in a one-component developing system, the amount is preferably in the range of 30 to 70% by weight based on the total amount of the toner particles. The reason for this is
If the amount of the magnetic particles is less than 30% by weight, the durability is reduced and fogging is likely to occur. On the other hand, if the added amount of the magnetic particles exceeds 70% by weight, the image density and durability may be reduced, or the fixability may be significantly reduced. Therefore, when applied to the one-component development system, it is more preferable to set the amount of the magnetic particles to a value within the range of 30 to 60% by weight. On the other hand, when applying to the two-component developing method, it is not necessary to add magnetic particles.
It is preferable to set the value to not more than% by weight. The reason for this is that if the amount of the magnetic particles exceeds 15% by weight, the durability is reduced and fogging is likely to occur. Therefore, when applied to the two-component development system, it is more preferable to set the amount of the magnetic particles to a value within the range of 0 to 10% by weight (however, 0% by weight is not included).

(5) Property improving agent The toner for developing an electrostatic latent image according to the present invention has the following properties in order to improve the fluidity and storage stability of the toner for developing an electrostatic latent image.
It is preferable to add colloidal silica or hydrophobic silica as a property improving agent, or to perform surface treatment using these colloidal silicas. Further, it is preferable that the amount of silica added is determined in consideration of the amount of titanium oxide added. Specifically, it is preferable that the addition amount of silica be a value within the range of 10 to 100% by weight, when the addition amount of titanium oxide is 100% by weight. The reason for this is
When the amount of the silica is less than 10% by weight,
This is because the effect of the addition of silica may not be exhibited. On the other hand, if the addition amount of the silica exceeds 100% by weight, the charging characteristics of the electrophotographic toner may be reduced. Therefore, when the addition amount of silica is 100% by weight, the addition amount of silica is 20 to 90%.
%, More preferably within a range of 30% by weight.
More preferably, the value is in the range of 80% by weight.

(6) Average Particle Size The average particle size of the toner for developing an electrostatic latent image is preferably set to a value within the range of 5 to 12 μm. The reason for this is that if the average particle diameter of the toner for developing an electrostatic latent image is less than 5 μm, the storage stability may be easily reduced. On the other hand, if the average particle size of the toner for developing an electrostatic latent image is larger than 12 μm, the transportability may be reduced, or the fixed image may be unclear. Therefore, the average particle diameter of the toner for developing an electrostatic latent image is more preferably set to a value within the range of 6 to 11 μm.

2. External Additives In the toner of the present invention, the charge amount distribution is uniform, showing stable charging characteristics without lowering the triboelectric charge amount and without charging up, and having fluidity, environmental dependency, and durability. In order to provide an excellent toner for developing an electrostatic latent image, both an anatase-type titanium oxide having an average particle diameter of less than 10 to 200 nm and a rutile-type titanium oxide having an average particle diameter of less than 200 to 500 nm are used as toner particles. It is necessary to perform external addition processing. That is, an anatase-type titanium oxide is added to exert a polishing force, and a rutile-type titanium oxide is added to sharpen a charge amount distribution, so that a synergistic effect is exhibited.

(1) Average particle size of anatase type titanium oxide The average particle size of anatase type titanium oxide is 10 to 200 n.
It is necessary to set the range to less than m. The reason is that the average particle size of such anatase type titanium oxide is 200 nm.
If the above values are obtained, the photoreceptor may be damaged, and dispersion and mixing with the magnetic ink particles may be difficult. However, when the average particle size of the anatase type titanium oxide is less than 10 nm, the polishing power for the photoreceptor decreases, and the fluidity, the environment dependency,
In addition, it may be difficult to provide an electrostatic latent image developing toner having excellent durability. Therefore, it is more preferable to set the average particle diameter of the anatase type titanium oxide to a value within the range of 120 to 180 nm. The average particle size of the anatase type titanium oxide means the average primary particle size when the anatase type titanium oxide is aggregated. The average particle size of the anatase type titanium oxide and the rutile type titanium oxide described below can be measured using a particle counter or the like employing a laser method.

When the electrostatic latent image developing toner is used for an OPC photosensitive member, the volume resistivity of the anatase type titanium oxide is set to 1
The value is preferably in the range of × 10 ⁴ to 1 × 10 ¹⁵ Ω · cm, and when used for a-Si photoreceptor, the volume resistivity of the anatase type titanium oxide is 1 × 10 ¹ to 1 ×.
It is preferable that the value be in the range of 10 ⁷ Ω · cm. The reason for this is that when the electrostatic latent image developing toner is used for the OPC photoreceptor and the volume resistivity of the anatase type titanium oxide falls outside such a range, the electrostatic latent image developing toner is charged. This is because the characteristics are apt to be reduced, causing a decrease in image density, which may result in a blank image. Further, when used for a-Si photoreceptor, if the volume specific resistance of anatase type titanium oxide is 1 × 10 ⁷ Ω · cm or more, the charge amount becomes too high, the charge is increased, and the image density is reversed. In some cases, the durability may be reduced, and furthermore, due to excessive charge-up, when an a-Si photosensitive member is used, discharge breakdown may occur and a black point image may be formed. That's why. Therefore, when the electrostatic latent image developing toner is used for the OPC photoconductor, the volume resistivity of the anatase type titanium oxide is 1 ×
The value is more preferably in the range of 10 ⁵ to 1 × 10 ¹⁴ Ω · cm, and even more preferably in the range of 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm. When the electrostatic latent image developing toner is used for the a-Si photoreceptor, the volume resistivity of the anatase type titanium oxide is 1 × 10 ² to 1 ×.
The value is more preferably in the range of 10 ⁶ Ω · cm, and even more preferably in the range of 1 × 10 ³ to 1 × 10 ⁵ Ω · cm.

The volume resistivity of the anatase type titanium oxide and the rutile type titanium oxide to be described later is ULTRA HI.
GH RESISTANCE METER (Advantest R8340A)
And applying an applied voltage of DC1 while applying a load of 1 kg.
It can be obtained under the condition of 0V.

(2) Rutile-type titanium oxide average particle diameter The average particle diameter of rutile-type titanium oxide is 200 to 500 nm.
It is necessary to set the value within the range of less than. The reason is that the average particle size of such rutile type titanium oxide is 500 n.
If it exceeds m, uniform charging characteristics may be exhibited, or dispersion and mixing with magnetic ink particles may be difficult. On the other hand, when the average particle diameter of the rutile-type titanium oxide is less than 200 nm, uniform charging characteristics may be exhibited and aggregation may be easily caused. Therefore, it is more preferable to set the average particle diameter of the rutile type titanium oxide to a value within the range of 200 to 300 nm.

When the electrostatic latent image developing toner is used for an OPC photosensitive member, the volume resistivity of the rutile type titanium oxide is set to 1 × 1.
0 ⁴ is preferably set to a value within the range of ^{~1 × 10 15 Ω · cm,} a-Si when used in the photosensitive body, the volume resistivity of the rutile type titanium oxide ¹ × 10 1 ~1 × 10 ⁷ Ω
It is preferable that the value be in the range of cm. The reason for this is
When the electrostatic latent image developing toner is used for the OPC photoreceptor, if the volume resistivity of the rutile type titanium oxide falls outside such a range, the charging characteristics of the electrostatic latent image developing toner deteriorate. This is because the image density tends to be low and the image density may be reduced, resulting in a blank image. Also, a
-When used for a Si photoreceptor, if the volume resistivity of the rutile type titanium oxide is 1 × 10 ⁷ Ω · cm or more, the charge amount is too high, the charge is increased, and the image density is reduced. Or the durability may be reduced. Further, due to excessive charge-up, a-Si
This is because when a photoconductor is used, discharge breakdown may occur and a black spot image may be formed. Therefore, when the electrostatic latent image developing toner is used for the OPC photoreceptor, the volume resistivity of the rutile type titanium oxide is 1 × 10 ⁵ to 1 × 10 ^14.
More preferably, the value is within the range of Ω · cm.
More preferably, the value is in the range of 10 ⁶ to 1 × 10 ¹³ Ω · cm. Further, the toner for developing an electrostatic latent image is a-S
When used for an i photoreceptor, the volume resistivity of the rutile type titanium oxide is more preferably set to a value within the range of 1 × 10 ² to 1 × 10 ⁶ Ω · cm, and 1 × 10 ³ to 1 ×. 10 ⁵ Ω
More preferably, the value is in the range of cm.

(3) Surface Treatment The above-mentioned titanium oxide may be subjected to a surface treatment with a surface treating agent such as a titanate coupling agent or a silane coupling agent. That is, since the anatase-type titanium oxide and the rutile-type titanium oxide are generally hydrophilic, it is preferable to treat their surfaces with a titanate-based coupling agent or the like to make them hydrophobic.

(4) Addition ratio The addition ratio of the anatase type titanium oxide and the rutile type titanium oxide is set in a weight ratio of 10:90 to 90:10 with respect to the electrostatic latent image developing toner. It is preferable to use a value. The reason for this is that the amount of added anatase type titanium oxide is 10% of the total amount of the toner for developing an electrostatic latent image.
If the value is less than 90% (relatively, the value of rutile-type titanium oxide is 90% or more), polishing is insufficient, image flow occurs at high temperature and high humidity, and image defects may occur. On the other hand, when the added amount of the anatase type titanium oxide is 90% or more (relatively, the value of the rutile type titanium oxide is less than 10%) with respect to the total amount of the electrostatic latent image developing toner, This is because the charge amount of the toner for developing an electrostatic latent image exceeds an appropriate value, causing charge-up, broadening the charge amount distribution, and as a result, lowering the image density and deteriorating the durability. . Therefore, it is preferable that the addition ratio of the anatase type titanium oxide and the rutile type titanium oxide be a value within a range of 20:80 to 80:20 by weight, and a value within a range of 30:70 to 70:30. More preferably,

Here, with reference to FIGS. 2 to 5, the relationship between the addition ratio of anatase-type titanium oxide / rutile-type titanium oxide and the charging characteristics, image density, fogging property, and image flow property will be described. The horizontal axis of FIG. 2 shows the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide, and the vertical axis of FIG. 2 shows the charge amount (μC / g). It is. The initial charge (μC / g) is shown by a solid line, and the charge after durability (μC / g) is shown by a dotted line. As can be easily understood from FIG. 2, when the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide is in the range of 10/90 to 90/10, the initial charge amount and the charge amount after durability are also increased. However, when the addition ratio (weight ratio) is 95/5 to 100/0, the value of the charge amount increases, and moreover, charge-up occurs in which the value changes greatly after endurance. Therefore, in order to stabilize the initial charge amount and the charge amount after endurance, it is effective to set the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide to 90/10 or less. Understood.

The horizontal axis of FIG. 3 shows the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide, and the vertical axis of FIG. 3 shows the image density (−). Taken and shown. The initial image density (-) is shown by a solid line, and the image density (-) after durability is shown by a dotted line. As can be easily understood from FIG. 3, the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide is 1
In the range of 0/90 to 90/10, an image density of about 1.40 can be obtained both at the initial stage and after the endurance, and the image density is stable, but the addition ratio (weight ratio) is 95/5 to 100/0. Then, the image density is reduced to about 1.2 to 1.3 both at the initial stage and after the endurance. Therefore, in order to stabilize the image density at the initial stage and after the endurance, anatase type titanium oxide /
The addition ratio (weight ratio) of rutile-type titanium oxide is 90/10
It is understood that the following values are effective.

The horizontal axis of FIG. 4 shows the addition ratio (weight ratio) of anatase type titanium oxide / rutile type titanium oxide, and the vertical axis of FIG.
(Relative value) is shown. The initial evaluation of fog (relative value) is shown by a solid line, and the evaluation of fog after durability (relative value) is shown by a dotted line. The evaluation score of fog was calculated by setting the evaluation of fog to 3 points, the evaluation of fog to 1 point, and the evaluation of fog x to 0 points. As can be easily understood from FIG. 4, if the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide is in the range of 10/90 to 90/10,
The evaluation point of the fog property is stable at 3 points both at the initial stage and after the endurance, but the addition ratio (weight ratio) is 95/5 to 100/0.
, The evaluation point of the fogging property is reduced to about 0 to 1 both at the initial stage and after the endurance. Therefore, in order to improve the fog properties at the initial stage and after the durability, it is effective to set the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide to 90/10 or less. Is understood.

The horizontal axis of FIG. 5 shows the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide, and the vertical axis of FIG.
(Relative value) is shown. In addition, evaluation of image flowability
Are evaluated as three points, the evaluation 像 of the image flowability is set as one point, and the evaluation of the image flowability × is set as 0 point, and the evaluation points of the fogging property are calculated. As can be easily understood from FIG. 5, if the addition ratio (weight ratio) of anatase-type titanium oxide / rutile-type titanium oxide is in the range of 10/90 to 90/10,
The evaluation point of image flowability was stable at 3 points both at the initial stage and after the endurance, but the addition ratio (weight ratio) was 5/95 to 0/100.
In this case, the evaluation point of image flowability is lowered to about 0 to 1 both at the initial stage and after the endurance. Therefore, in order to improve the image flowability at the initial stage and after the endurance, it is effective to set the addition ratio (weight ratio) of anatase type titanium oxide / rutile type titanium oxide to a value of 10/90 or more. It is understood that.

(5) Addition amount The total addition amount of the anatase type titanium oxide and the rutile type titanium oxide is a value within the range of 0.5 to 5% by weight based on the total amount of the toner particles. It is preferable that The reason for this is that if the total amount is less than 0.5% by weight, the polishing effect on the photoreceptor becomes insufficient, or image flow occurs at high temperature and high humidity.
This is because an image defect may occur. on the other hand,
If the total amount is 5% by weight or more, the fluidity of the toner for developing an electrostatic latent image is extremely deteriorated, so that the image density and durability may be reduced. Therefore, it is more preferable that the total amount of anatase-type titanium oxide and rutile-type titanium oxide is set to a value in the range of 0.6 to 4.5% by weight, and more preferably in a range of 0.7 to 4.3% by weight. Is more preferable.

[0054]

Hereinafter, the present invention will be described in more detail with reference to examples. Needless to say, the following description is an exemplification of the present invention, and the scope of the present invention is not limited to the following description without any particular reason. Example 1 (1) Production of Toner for Developing Electrostatic Latent Image A mixture of styrene / acrylic resin, polyethylene wax and charge controlling agent was melt-kneaded by a twin-screw extruder so as to have the following composition. This was cooled, pulverized and classified to obtain toner particles having an average particle diameter of 7 μm. Anatase-type titanium oxide (average particle size 150 n
m, volume specific resistance 5 × 10 ⁴ Ω · cm) and rutile type titanium oxide (average particle diameter 250 nm, volume specific resistance 5 × 10 4
⁴ Ω · cm) was added so as to be 2% by weight in total (10 parts by weight / 90 parts by weight), and further, 0.5% by weight of silica fine particles (SiO ₂ ) was externally added. This was designated as No. 1 electrostatic latent image developing toner. Styrene / acrylic resin 96 parts by weight Polyethylene wax 3 parts by weight Charge control agent 1 part by weight Anatase type titanium oxide 0.2 parts by weight Rutile type titanium oxide 1.8 parts by weight Silica fine particles 0.5 part by weight

(2) Evaluation of Toner for Developing Electrostatic Latent Image Charging Characteristics A mixture of 5 parts by weight of the obtained toner for developing an electrostatic latent image and 100 parts by weight of a ferrite carrier was mixed in a normal environment (20 ° C., 65
% RH), and the charge amount (μC / g) when frictionally charged under the conditions of 60 minutes was measured using a blow-off powder charge amount measurement device (manufactured by Toshiba Chemical Corporation) as the initial charge amount. In addition, Kyocera's page printer (FS-
3750), the charge amount of the toner for developing an electrostatic latent image after continuous printing of 100,000 sheets of A4 paper is defined as the charge amount after durability, and similarly using a blow-off powder charge amount measuring device. It was measured.

Image Characteristics The obtained toner for developing an electrostatic latent image was evaluated for image characteristics using the above-mentioned FS-3750. That is, the normal environment
(20 ° C., 65% RH), an image evaluation pattern was printed at the initial stage to obtain an initial image, and a solid image density was measured by a Macbeth reflection densitometer. At the same time, the fogging property was visually checked according to the following criteria. Then, FS-3 described above
Using 750, continuous printing of 100,000 sheets of A4 paper was performed, an image evaluation pattern was printed to make a durable image, and the solid image density was measured with a Macbeth reflection densitometer. At the same time,
The fogging property was visually observed according to the following criteria. ：: No fog occurred. Δ: Some fogging has occurred. X: Remarkable fog is generated.

Image Flow Property The image flow property of the obtained electrostatic latent image developing toner was evaluated. That is, using the above-mentioned FS-3750, continuous printing of 5,000 sheets of A4 paper was performed in a normal environment (20 ° C., 65% RH). Thereafter, it was left under a high-temperature and high-humidity environment (33 ° C., 85% RH) for a day and a night, and an image evaluation pattern was printed. ：: No image deletion was observed at all, and the image evaluation pattern was accurately reproduced. Δ: Image flow was slightly recognized, and part of the image evaluation pattern was not reproduced. X: Remarkable image flow was slightly recognized, and the reproducibility of the image evaluation pattern was poor.

[0058]

[Table 1]

[0059]

[Table 2]

Examples 2 to 7 and Comparative Examples 1 and 2 (1) Preparation of Toner for Developing Electrostatic Latent Image The effect of the addition ratio of anatase-type titanium oxide and rutile-type titanium oxide having a predetermined particle size was examined. did. Therefore, a toner for developing an electrostatic latent image was prepared in the same manner as in Example 1, except that the addition ratio was as shown in Table 1.

(2) Evaluation of the electrostatic latent image developing toner The obtained electrostatic latent image developing toner was evaluated in the same manner as in Example 1. Table 2 shows the obtained results. As can be easily understood from the results, by using a mixture of anatase type titanium oxide and rutile type titanium oxide having a predetermined particle size,
It was confirmed that a toner for developing an electrostatic latent image having a good balance in the charging characteristics, image characteristics, and image flow characteristics was obtained.

Comparative Examples 3 to 5 (1) Preparation of Toner for Developing an Electrostatic Latent Image In Comparative Example 3, an anatase type titanium oxide having an average particle size of less than 10 nm and a rutile type oxide having an average particle size of less than 200 nm were used. The effect of mixing with titanium was studied. In Comparative Example 4, the effect of mixing anatase-type titanium oxide having an average particle diameter of less than 10 nm with rutile-type titanium oxide having an average particle diameter of less than 200 to 500 nm was examined. In Comparative Example 5, the effect of mixing anatase-type titanium oxide having an average particle diameter of less than 10 to 200 nm with rutile-type titanium oxide having an average particle diameter of less than 200 nm was examined. Therefore, a toner for developing an electrostatic latent image was prepared in the same manner as in Example 1, except that anatase-type titanium oxide and rutile-type titanium oxide having different average particle diameters were used.

(2) Evaluation of the toner for developing an electrostatic latent image The obtained toner for developing an electrostatic latent image was evaluated in the same manner as in Example 1. Table 3 shows the obtained results. For reference,
The results of Example 1 are also shown. As can be easily understood from the results, if the anatase-type titanium oxide and the rutile-type titanium oxide having a predetermined particle size are not mixed and used, the electrostatic characteristics with good balance in the charging characteristics, image characteristics, and image flow characteristics are obtained. It was confirmed that a latent image developing toner could not be obtained.

[0064]

[Table 3]

[0065]

As is apparent from the above description, according to the toner for developing an electrostatic latent image of the present invention, both anatase type titanium oxide and rutile type titanium oxide having a predetermined average particle diameter are used as toner particles. Durability,
By imparting charging characteristics with excellent stability, high-quality images can be stably obtained at any temperature and humidity. Further, the toner for developing an electrostatic latent image according to the present invention has an excellent polishing force, so that an image defect due to image deletion does not occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus to which an electrostatic latent image developing toner of the present invention is applied.

FIG. 2 is a diagram provided to explain the relationship between the addition ratio of anatase-type titanium oxide / rutile-type titanium oxide and charging characteristics.

FIG. 3 is a diagram provided for explaining a relationship between an addition ratio of anatase-type titanium oxide / rutile-type titanium oxide and image density.

FIG. 4 is a diagram provided for explaining the relationship between the addition ratio of anatase-type titanium oxide / rutile-type titanium oxide and fog resistance.

FIG. 5 is a diagram provided for explaining a relationship between an addition ratio of anatase-type titanium oxide / rutile-type titanium oxide and image flowability.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Polygon mirror 5 Optical transmission mechanism 7 Top door 9 Photoconductor 10 Developing device 31 Toner container 32 Developing roller 33 Supply roller 39 Toner sensor 47 Display part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Masaki Ishii 704, Matabe, Noshino, Tamashi-cho, Tamaki-cho, Mie Prefecture 19 Within Kyocera Corporation's Mie Plant, Tamaki Block (72) Inventor Noriya Okamoto Tamaki-cho, Mie Prefecture 704 Nobashita Matabei 19 F-term (reference) in Tamaki block, Mie Plant, Kyocera Corporation 2H005 AA08 CA25 CB07 EA01 EA05 EA07 2H068 AA21 DA00

Claims (6)

[Claims] An anatase type titanium oxide having an average particle size of less than 10 to 200 nm and an average particle size of 200 to 500
A toner for developing an electrostatic latent image, wherein both of rutile-type titanium oxide having a particle diameter of less than 10 nm and toner particles are externally added to toner particles. 2. The weight ratio of the anatase type titanium oxide to the rutile type titanium oxide is from 10:90 to 9: 9.
2. A value within a range of 0:10.
3. The toner for developing an electrostatic latent image according to item 1. 3. The toner according to claim 1, wherein the total amount of the anatase type titanium oxide and the rutile type titanium oxide is in a range of 0.5 to 5% by weight based on the toner particles. 3. The toner for developing an electrostatic latent image according to 1 or 2. 4. When the electrostatic latent image developing toner is used for an organic photoreceptor, the anatase type titanium oxide and the rutile type titanium oxide each have a volume resistivity of 1 × 1.
0 ⁴ within a range of ~1 × 10 ¹⁵ Ω · cm, amorphous silicon in the case of using the photoreceptor, the anatase type titanium oxide and rutile titanium oxide having a volume resistivity of each 1 × 10 ¹ to 1 The electrostatic latent image developing toner according to any one of claims 1 to 3, wherein the toner has a value within a range of × 10 ⁷ Ω · cm. 5. The surface treatment of the rutile-type titanium oxide and the anatase-type titanium oxide, respectively, with a titanate-based coupling agent.
The toner for developing an electrostatic latent image according to any one of the above items. 6. The electrostatic latent image developing toner according to claim 1, which is applied to a printer equipped with an organic photoreceptor.