JP2835990B2 - toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a toner for developing an electrostatic image in electrostatic printing or the like.

[0002]

2. Description of the Related Art It is well known in the art to form and develop an image on the surface of a photoconductive material by electrostatic means.

That is, US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-2
A number of methods are known, such as Japanese Patent No. 4748, but generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the toner is called a toner on the latent image. A toner image corresponding to an electrostatic latent image is formed by attaching an extremely finely pulverized inspection material.

Then, if necessary, the toner is transferred to the surface of an image support such as paper, and then fixed by heating, pressurizing or solvent vapor to obtain a copy. When a step of transferring a toner image is provided, a step for removing residual toner is usually provided.

[0005] A developing method for visualizing an electric latent image by using a toner is described in, for example, a powder cloud method described in US Pat. No. 2,221,776, and US Pat. No. 2,618,55.
No. 2,874,063, a magnetic brush method, and a conductive property described in 3,909,258. A method using a magnetic toner is known.

As a toner applied to these developing methods, a toner obtained by mixing and dispersing a colorant in a thermoplastic resin and then pulverizing the same is used. As the thermoplastic resin, a polystyrene resin is the most common, but a polyester resin, an epoxy resin, an acrylic resin, a urethane resin, or the like is also used. As a coloring agent, carbon black is most widely used, and in the case of a magnetic toner, iron oxide black magnetic powder is often used. In the case of using a so-called two-component developer, the toner is usually glass beads,
It is used by being mixed with carrier particles such as iron powder.

[0007] The toner image on the final copy image forming member such as paper is permanently fixed on the support by heat, pressure or the like. Conventionally, this fixing step has often been performed by heat.

When a step of transferring a toner image is provided, a step for removing residual toner on the photoreceptor is usually provided.

In recent years, the development of monocolor copying to full-color copying in copying machines and the like has been rapidly progressing, and the study and commercialization of two-color copying machines and full-color copying machines have been greatly increased. For example, “Journal of the Society of Electrophotography,” Vol.
22, no. 1 (1983) and "Journal of the Institute of Electrophotography" Vo
l 25, No. 1, P52 (1986).

[0010] However, full color electrophotography which is not practically compared with the real thing like a television, a photograph, and a color print, and which is regarded as a color image which is more beautifully processed than the real thing, is now in practical use. The images are not always satisfactory.

[0011] Color image formation by full-color electrophotography generally reproduces all colors using three primary color toners of yellow, magenta, and cyan.

In the method, first, an electrostatic latent image is formed on a photoconductive layer by passing light from a document through a color separation light transmission filter having a complementary color relationship with the color of the toner, and then the toner is developed and transferred. Hold on the support. This process is sequentially performed a plurality of times, and while the registration is being performed, the toner is overlaid on the same support, and the final full-color image is obtained by one-time fixing.

Generally, in the case of a so-called two-component developing system in which a developer is composed of a toner and a carrier, the developer charges the toner to a required charge amount and charge polarity by friction with the carrier, and utilizes electrostatic attraction. Therefore, in order to obtain a good visible image, it is necessary for the toner to have good triboelectric charging properties mainly determined by the relationship with the carrier.

[0014] To solve the above-mentioned problems, search for a carrier core agent and a carrier coating agent and optimization of the coating amount, or study of a charge control agent and a fluidity imparting agent to be added to the toner, and further, a binder as a base Many studies have been made to achieve excellent triboelectrification in all materials constituting a developer, such as improvement of the developer.

For example, Japanese Patent Publication No. 52-25656 discloses a technique for adding a charge auxiliary agent such as chargeable fine particles to a toner.
JP-A-56-64352 and JP-A-61-160760 each add a fine resin powder having a polarity opposite to that of a toner to a developer.
Techniques for obtaining stable triboelectric charging properties have been proposed, and many charging aids have been developed today.

Further, various techniques have been devised as a method for adding the charging auxiliary as described above. For example, a method of attaching the toner particles to the surface of the toner particles by electrostatic force or van der Waals force between the toner particles and the charge auxiliary agent is generally used, and a stirrer, a mixer or the like is used. However, in this method, it is not easy to uniformly disperse the additive on the surface of the toner particles, and the presence of the additive which is not attached to the toner particles but aggregates together, that is, in a so-called free state is considered. It is difficult to avoid. This tendency becomes more conspicuous as the specific electrical resistance of the charging aid increases and as the particle size decreases. In such a case, the performance of the toner is affected. For example, the amount of triboelectric charge becomes unstable, the image density is not constant, and the image has a lot of fog.

[0017] Or, if continuous copying or the like is performed, the content of the charging aid changes, and the image quality at the initial stage cannot be maintained.

As another addition method, there is a method in which a charging auxiliary is added in advance together with a binder resin and a colorant at the time of manufacturing a toner. However, it is not easy to make the charge control agent uniform, and it is substantially in the vicinity of the toner particle surface that contributes to the chargeability, and the charge auxiliary agent and the charge control agent present inside the toner particles are charged. Therefore, it is not easy to control the amount of the charge auxiliary agent added and the amount of dispersion on the surface. Also, in the toner obtained by such a method, the triboelectric charge amount of the toner is unstable, and it is not easy to obtain a toner satisfying the developer characteristics as described above. The fact is that satisfactory quality has not been obtained.

In recent years, the demand for higher definition and higher image quality of copying machines has been increasing in the market, and in the technical field, attempts have been made to achieve high image quality and color by reducing the particle size of toner. However, as the particle size becomes smaller, the surface area per unit weight tends to increase, and the amount of charge of the toner tends to increase. In addition, since the charged amount of the toner is large, the adhesion between the toners is strong, the fluidity is reduced, and problems occur in the stability of toner supply and in the application of tribo to the supplied toner.

In the case of a color toner, since it does not contain a magnetic substance or a conductive substance such as carbon black, there is no charge leakage portion, and the amount of charged electricity generally tends to be large. This tendency is more remarkable especially when a polyester binder having high charging performance is used.

In particular, in the case of a color toner, the following properties are strongly desired. (1) In order that the fixed toner does not diffusely reflect light and hinder color reproduction, the toner needs to be in a state of almost complete melting such that the shape of the toner particles cannot be determined. (2) It must be a colored toner having transparency that does not interfere with the toner layers of different colors under the toner layer. (3) Each of the constituent toners must have balanced hue and spectral reflection characteristics and sufficient saturation.

From this point of view, many binder resins have been studied, but a toner satisfying all the above characteristics has not yet been developed. Today, polyester resins are widely used as binder resins for color in the technical field. However, toners made of polyester resins are generally easily affected by temperature and humidity, and have an excessive charge amount under low humidity and high humidity. Under such circumstances, there arises a problem such as insufficient charge amount, and there is an urgent need to develop a color toner having a stable charge amount even in a wide range of environments.

[0023]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic charge which has solved the above-mentioned problems.

That is, an object of the present invention is to provide a toner for electrostatic charge development which is hardly influenced by the environment such as temperature and humidity, exhibits good fluidity, and has always stable triboelectricity.

A further object of the present invention is to provide a toner for electrostatic charge development which has clear image characteristics without fog and has excellent durability stability.

[0026]

According to the present invention, the present invention relates to a method for treating a surface of an aqueous system with a silicone oil or a silicone varnish and then treating the surface with the following general formula (I):

[0027]

Embedded image (Wherein, n is an integer of 4 to 12 and m is an integer of 1 to 3), which contains titanium oxide which has been treated while hydrolyzing in an aqueous system with a coupling agent represented by the following formula: ~ 1
0 μm.

As an example of a toner containing hydrophobic titanium oxide, JP-A-59-52255 has proposed a toner containing titanium oxide treated with an alkyl trialkoxysilane. Although the electrophotographic properties have been improved by the addition of, the surface activity of titanium oxide is inherently small, resulting in the formation of coalesced particles in the processing stage and the non-uniform hydrophobicity. Was not always satisfactory.

The present inventors have conducted intensive studies on stabilizing the chargeability of the toner. As a result, after treating a specific silicone oil or silicone varnish in an aqueous system, the specific coupling agent was hydrolyzed in the aqueous system. It has been found that the treated titanium oxide having an average particle size of 0.01 to 0.2 μm and a degree of hydrophobicity of 40 to 80% can be subjected to a uniform hydrophobic treatment and that there is no coalescence between the particles. It has been found that the obtained toner is extremely effective in stabilizing charging and imparting fluidity.

The purpose of this was to seal the functional groups of titanium oxide remaining after treatment with silicone oil or silicone varnish with a coupling agent. Or it was found to be very high due to being treated with silicon varnish. The reason for this is not clear yet, but since the organic treatment has been performed in advance, the affinity between the site other than the reactive group of the coupling agent and the lipophilic site on the titanium oxide surface is good, and the reaction efficiency is improved. It is presumed that this is the case.

Therefore, in the present invention, a coupling agent can be selected in a very wide range from a low viscosity to a high viscosity, which is very effective in imparting charging ability and fluidity.

In the general formula (I), n is from 3 to 12, preferably from 4 to 4, in the coupling agent according to the present invention.
10 is good, and m is 1 to 3, preferably 1 to 2.

Here, n in the general formula of the coupling agent
Is smaller than 3, the treatment becomes easy, but the hydrophobicity cannot be sufficiently achieved. If n is larger than 12, the hydrophobicity is sufficient, but the coalescence of the titanium oxide particles increases, and the ability to impart fluidity is reduced.

On the other hand, if m is larger than 3, the reactivity is lowered and the hydrophobic treatment is not sufficiently performed.

The processing amount of silicon oil or silicon varnish is 0.1 to 1 with respect to 100 parts by weight of titanium oxide.
0 parts by weight, preferably 1 to 7 parts by weight, and the treatment amount of the coupling agent is 5 to 100 parts by weight of titanium oxide.
The amount may be 30 parts by weight, and the degree of hydrophobicity may be 40 to 80%, preferably 50 to 80%.

That is, if the degree of hydrophobicity is less than 40%, the amount of charge is greatly reduced due to long-term storage under high humidity, and a mechanism for promoting charging on the hard side is required, which complicates the apparatus. When the degree of conversion exceeds 80%, it becomes difficult to control the charging of titanium oxide itself, and as a result, the toner is charged up under low humidity.

Further, the particle size of the particles is set at 0.1 from the viewpoint of imparting fluidity.
01 to 0.2 μm is good. If the particle size is larger than 0.2 μm, toner charging due to poor fluidity becomes non-uniform, resulting in toner scattering and fogging. Also, 0.0
If the thickness is smaller than 1 μm, the toner is easily embedded on the toner surface, the toner deteriorates quickly, and the durability decreases. This tendency is more remarkable in the sharp-melt color toner used in the present invention.

In the present invention, the titanium oxide is treated with a silicone oil or a varnish while mechanically dispersing the titanium oxide in an aqueous system so as to have a primary particle diameter, and further hydrolyzing the coupling agent. The treatment method is effective and is preferable in that no solvent is used.

The silicone oil used in the present invention is not particularly limited, but has the general formula

[0040]

Embedded image (R ₁ and R ₂ are CH ₃ or OH) dimethylpolysiloxane type represented by the general formula

[0041]

Embedded image A methylhydrogenpolysiloxane type represented by the general formula

[0042]

Embedded image And a methylphenylpolysiloxane type represented by Further, if necessary, alkyl modification,
Amino modification, epoxy modification, epoxy / polyether modification, carboxyl modification, mercapto modification, alcohol modification, fluorine modification and the like may be performed.

The silicone oil preferably has a viscosity at 25 ° C. of 50 to 1000 centistokes. If it is less than 50 centistokes, the volatile component is large, and the treatment effect is not long lasting.

If it exceeds 1,000 centistokes, it becomes difficult to perform uniform treatment in an aqueous system, and the treatment efficiency is extremely deteriorated.

The silicone varnish used in the present invention is also 2
It does not matter if the viscosity at 5 ° C. is 50 to 1000 centistokes.

Further, in the present invention, the treated titanium oxide has a light transmittance of 40% at a light length of 400 nm when dispersed in an ethanol solvent at a solid concentration of 0.1%.
This is one of the features.

That is, when the titanium oxide of the present invention is used as a full-color toner, if the transmittance with respect to visible light is poor, the projected image of the OHP is blurred and a clear image cannot be obtained.

The transmittance in the present invention was measured by UV2200 manufactured by Shimadzu Corporation.

The toner has a weight average particle diameter of 5 to 10 μm.
Even when the particle size is reduced, the titanium oxide of the present invention is suitable. When the particle size of the toner is reduced, the surface area per weight increases, and excessive charging due to rubbing is likely to occur. On the other hand, titanium oxide fine particles which can control charging and impart fluidity have a great effect.

The toner according to the present invention may contain a charge control agent for stabilizing the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable. Examples of the negative charge control agent in this case include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid). When the negative charge control agent is blended with the toner, 0.1 to 12 parts by weight per 100 parts by weight of the binder resin is used.
It is advisable to add 0.5 parts by weight, preferably 0.5 to 8 parts by weight.

When a two-component developer is prepared by mixing with the toner according to the present invention, the mixing ratio is preferably 2 to 10% by weight, and more preferably 3 to 9% by weight, as the toner concentration in the developer. Results are obtained. If the toner concentration is less than 2% by weight, the image density becomes too low to be practical and 10% by weight.
Exceeding fog increases fog and in-machine scattering and shortens the useful life of the developer.

As the colorant used in the present invention, known dyes and pigments such as phthalocyanine blue, indaslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hanza yellow, permanent yellow and benzidine yellow are widely used. can do. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to reflect sensitively on the permeability of the OHP film.

Additives may be added to the toner of the present invention as needed as long as the properties of the toner are not impaired. Examples of such additives include Teflon, zinc stearate, and polyvinylidene fluoride. Lubricants, fixing aids (eg, low molecular weight polyethylene, low molecular weight polypropylene, etc.), and organic resin particles.

In the production of the toner of the present invention, the constituent materials are kneaded well by a hot kneader such as a hot roll, kneader, extruder or the like, and then mechanically pulverized and classified to obtain a toner. After dispersing a material such as a colorant in the method obtained by spray drying, or
After mixing the predetermined material with the monomer that should constitute the binder resin,
Each method such as a polymerization toner production method of obtaining a toner by polymerizing this emulsion suspension can be applied.

As the binder used in the colorant-containing resin particles of the present invention, various material resins conventionally known as electrophotographic toner binder resins are used.

For example, styrene-based copolymers such as polystyrene, styrene-butadiene copolymer and styrene-acrylic copolymer, and ethylene-based copolymers such as polyethylene, ethylene-vinyl acetate copolymer and ethylene-vinyl alcohol copolymer Copolymer, phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, maleic acid resin and the like. In addition, the production method of any resin is not particularly limited.

The effect of the present invention is remarkable when a polyester resin having a high negative chargeability is used among these resins. That is, the polyester-based resin has excellent fixability and is suitable for a color toner, but has a high negative charging ability and tends to be excessively charged. A toner is obtained.

In particular, the following equation

[0059]

Embedded image (Wherein R is an ethylene or propylene group, x, y
Is an integer of 1 or more, respectively, and the average value of x + y is 2 to 10. A) a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid) Acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) are more preferred because they have sharp melting properties.

When the toner of the present invention is used as a two-component developer using a carrier, an electrically insulating resin is used as a coating resin on the surface of the carrier, but is appropriately selected depending on the toner material and the carrier core material. . In the present invention, at least one monomer selected from at least an acrylic acid (or an ester thereof) monomer and a methacrylic acid (or an ester thereof) monomer in order to improve the adhesion to the carrier core material surface. Must be contained.
In particular, when a polyester resin particle having a high negative chargeability is used as the toner material, it is preferable to further form a copolymer with a styrene monomer for the purpose of stabilizing the charge, and the copolymerization weight ratio of the styrene monomer is preferable. Is preferably 5 to 70% by weight.

Examples of the monomer for the coating resin of the carrier core material usable in the present invention include:
For example, styrene monomer, chlorostyrene monomer, α
-Methylstyrene monomer, styrene-chlorostyrene monomer and the like. Examples of the acrylic monomer include, for example, acrylate monomer (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer, octyl acrylate monomer, phenyl acrylate monomer) And methacrylic acid ester monomers (methyl methacrylate monomer, ethyl methacrylate monomer, butyl methacrylate monomer, phenyl methacrylate monomer).

The carrier core material (magnetic particles) used in the present invention includes, for example, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earths and the like, and their alloys or oxides, which are not oxidized or surface oxidized. Things can be used.
Also, there is no particular restriction on the manufacturing method.

Next, an example of an image forming apparatus for performing non-magnetic one-component development using the toner of the present invention will be described. However, the present invention is not necessarily limited to this. In FIG.
2 shows an apparatus for developing an electrostatic image formed on a latent image holding member. Reference numeral 1 denotes a latent image holding member, and a latent image is formed by an electrophotographic process unit or an electrostatic recording unit (not shown). 2
Denotes a developer carrier, which is formed of a nonmagnetic sleeve made of aluminum, stainless steel, or the like. The non-magnetic one-component color toner is stored in the hopper 3 and is supplied by the supply roller 4 onto the developer carrier. The supply roller 4 also removes the toner on the developer carrier after development. The toner supplied on the developer carrier is uniformly and thinly applied by the developer application blade 5.
The effective contact pressure between the developer coating blade and the developer carrier is 3 to 250 g / cm, preferably 10 to 120 g / cm, as the linear pressure in the sleeve generatrix direction. If the contact pressure is less than 3 g / cm, it becomes difficult to apply the toner uniformly, and the charge amount distribution of the toner becomes broad, causing fogging and scattering. On the other hand, if the contact pressure exceeds 250 g / cm, a large pressure is applied to the toner, so that the toners are undesirably aggregated or pulverized. By adjusting the contact pressure to 3 to 250 g / cm, it becomes possible to loosen the agglomeration peculiar to the small particle size toner, and it is possible to instantly increase the charge amount of the toner. The developer coating blade is preferably made of a material of a triboelectric series suitable for charging the toner to a desired polarity.

In the present invention, silicone rubber, urethane rubber, styrene-butadiene rubber and the like are preferred. Further, it may be coated with a polyamide resin or the like. Use of a conductive rubber or the like is preferable because the toner can be prevented from being excessively charged.

In the system proposed in the present invention in which a thin layer of toner is coated on a developer carrier by a blade, the thickness of the toner layer on the developer carrier is adjusted to obtain a sufficient image density. It is necessary to make the length of the gap between the developer carrier and the latent image holding body smaller than the gap length, and to apply an alternating electric field to this gap. That is, by applying an alternating electric field or a developing bias in which a DC electric field is superimposed on the alternating electric field between the developer carrier and the latent image carrier by the bias power source 6 shown in FIG. The transfer of the toner onto the body is facilitated, and a higher quality image can be obtained.

Hereinafter, the measuring method of the present invention will be described. (1) Toner particle size measurement: The particle size distribution can be measured by various methods. In the present invention, the measurement was performed using a Coulter counter.

That is, a Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting the number average distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were connected. The electrolyte is 1% sodium chloride.
% NaCl aqueous solution is prepared. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution.
Add 5 ml, and further add 2-20 mg of the measurement sample.
The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of the toner were measured using the Coulter Counter TA-II, using a 100 μm aperture as the aperture. The volume distribution and number distribution of 〜40 μm were calculated. Then, according to the present invention, the weight-average weight average diameter (D
4) (The median value of each channel is taken as a representative value for each channel), the amount of weight-based coarse powder (1
6.0 μm or more), and the number-based fine powder number (5.04 μm or less) determined from the number distribution. (2) Hydrophobicity measurement: The methanol titration test is an experimental test for confirming the hydrophobicity of a titanium oxide fine powder having a hydrophobized surface.

The "methanol titration test" defined herein for evaluating the degree of hydrophobicity of the treated fine titanium oxide powder is carried out as follows. 0.2 g of the test titanium oxide fine powder was added to 50 m of water in a 250 ml Erlenmeyer flask.
Add to l. Methanol is titrated from the burette until all of the titanium oxide is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed as the entire amount of titanium oxide fine powder is suspended in the liquid, and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water at the end point.

Hereinafter, the present invention will be described in detail with reference to examples.

[0070]

【Example】

(Production Example 1 of Titanium Oxide) Hydrophilic titanium oxide fine particles (particle diameter: 0.05 μm, BET: 120 m ² / g) were mixed and stirred in an aqueous system, and as a treatment agent, dimethylpolysiloxane having a viscosity of 500 centistokes at 25 ° C. was used. Was dispersed in an aqueous system to form an emulsion, and the mixture was added and mixed so as to be 5% of the titanium oxide fine particles in terms of solid content so that the particles did not coalesce.
%, An average particle diameter of 0.05 μm, and titanium oxide fine particles a having a transmittance of 50% at 400 nm were obtained.

(Production Example 2 of Titanium Oxide) Titanium oxide a
Are mixed and stirred in water, and nC ₈ H ₁₇ —Si— (OCH
₃ ) Disperse ₃ into an aqueous system to form an emulsion, and add and mix the treating agent to the titanium oxide fine particles so that the solid content is 20% by weight so that the particles do not coalesce, and then dry and crush. 70% hydrophobicity, average particle size 0.05 μm, 40
Titanium oxide b having a transmittance of 55% at 0 nm was obtained.

(Production Examples 3 and 4 of Titanium Oxide) In Production Example 2, n-C ₆ H ₁₃ -Si-
_{(OCH 3) 3, n-} C 10 H 21 -Si- (OCH 3) 3
Respectively, using a degree of hydrophobicity of 60% and an average particle size of 0.
05 μm, titanium oxide c having a transmittance of 60% at 400 nm, a hydrophobicity of 70%, and an average particle diameter of 0.05 μm.
m, titanium oxide d having a transmittance of 50% at 400 nm was obtained.

(Production Example 5 of Titanium Oxide) The procedure of Production Example 1 was repeated except that 25% by weight of dimethylpolysiloxane was used.
m, titanium oxide e having a transmittance of 40% at 400 nm was obtained.

(Production Example 6 of Titanium Oxide) Production Example 2 except that the hydrophilic titanium oxide of Production Example 1 was further sintered at a high temperature.
In the same manner as described above, the degree of hydrophobicity is 80%, the average particle size is 0.3 μm,
Titanium oxide f having a transmittance of 5% at 400 nm was obtained.

(Production Example 7 of Titanium Oxide) Oxidation having a hydrophobicity of 45%, an average particle diameter of 0.05 μm, and a transmittance of 60% at 400 nm was conducted in the same manner as in Production Example 2, except that the treating agent was used at 10% by weight. Titanium g was obtained.

Example 1 Polyester resin obtained by condensation of 100 parts of propoxylated bisphenol and fumaric acid 4 parts of phthalocyanine pigment 4 parts of chromium complex of di-tert-butylsalicylic acid 4 parts were sufficiently premixed with a Henschel mixer, and 3 parts of The mixture was melt-kneaded at least twice with a roll mill, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by a fine pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to select a particle size of 2 to 10 μm so as to have the particle size distribution of the present invention, thereby obtaining colorant-containing resin particles.

The particles were mixed with 1.0% of titanium oxide b using a Henschel mixer to obtain a cyan toner. This cyan toner had a weight average diameter of 8.2 μm.

To 5 parts of this toner, a copolymer (weight average molecular weight: 200,000) composed of 75% methyl methacrylate and 25% butyl acrylate was used.
m, 4.2% 35% or less, 35% 40% 9.5%,
Cu—Zn— having a particle size distribution of not less than 74 μm and 0.2%
A carrier in which 0.5% of an Fe-based ferrite carrier was coated was mixed to make a total amount of 100 parts to prepare a developer.

Using this developer, a commercially available plain paper color copying machine (Color Laser Copier 500, manufactured by Canon Inc.) was used to set the development contrast to 300 V and at 23 ° C./65%
Imaged below. The obtained image is Macbeth RD9
The reflection density was measured using an SPI filter on a Model 18 (the same applies to the following image density measurement method). The image density was as high as 1.51 and clear without any fog. The OHP projection image was also clear and clear. Thereafter, 10,000 copies were further made, during which the density fluctuation was as small as 0.08, and the fog and sharpness were the same as those at the initial stage. Under low temperature and low humidity (20 ℃,
(10% RH), the development contrast was set to 300 V, and image formation was performed. The image density was as high as 1.46, suggesting that the present invention was effective in controlling the charge amount under low humidity. ing.

Further, even under high temperature and high humidity (30 ° C./80%)
Similarly, when the development contrast was set to 300 V and an image was formed, an image having a very stable and excellent image density of 1.55 was obtained.

Further, 23 ° C./60% RH, 20 ° C./10
%, 30 ° C./80%, no abnormality was observed in the initial image after being left for one month in each environment.

Example 2 Example 2 was repeated except that titanium oxide c was used instead of titanium oxide b.
Although the image density slightly increased to 1.54 to 1.61 at 0%, good results were obtained.

Example 3 Example 3 was repeated, except that titanium oxide d was used instead of titanium oxide b.
At 0%, the image density slightly decreased to 1.40 to 1.46, but good results were obtained.

Comparative Example 1 The procedure of Example 1 was repeated, except that titanium oxide a was used instead of titanium oxide b.
At 0%, the image density increased to 1.70, and fog was slightly observed.

Comparative Example 2 The same procedure as in Example 1 was carried out except that titanium oxide e was used instead of titanium oxide b in Example 1, and the result was 30 ° C. /
When left at 80% for one month, the image density increased to 1.75, and fog and toner scattering were slightly observed.

Comparative Example 3 The same procedure as in Example 1 was carried out except that titanium oxide f was used instead of titanium oxide b in Example 1, resulting in a decrease in fluidity and image quality, and a reduction in OHP projection image. The clarity has deteriorated.

Example 4 A developing device of a commercially available color copying machine (Color Laser Copier 500, manufactured by Canon) was modified as shown in FIG. 1 and 3,000 sheets were printed in the same manner as in Example 1 except that no carrier was used. When image formation was performed, the image density was 1.47 to 1.51 at 20 ° C./10%, 1.50 to 1.53 at 23 ° C./65%, and 1.50 at 30 ° C./80%. １．５1.57, a good result was obtained.

Example 5 The same procedures as in Example 1 were carried out except that titanium oxide g was used, and the image density was 1.56-1.30 at 30 ° C./80%.
Good results were obtained although it was as high as 65.

[0089]

According to the present invention, by improving the fine oxide particles, particularly by using titanium oxide treated with a coupling agent having a specific structure, it is possible to stabilize the charge in various environments, and to improve the charge stability. It shows fluidity and achieves high image quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of a developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 latent image holder 2 developer carrier 3 hopper 4 supply roller 5 developer coating blade 6 power supply

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-345169 (JP, A) JP-A-61-257662 (JP, A) JP-A-5-72797 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. After surface treatment with silicone oil or silicone varnish in an aqueous system, the following general formula (I): (Wherein, n is an integer of 3 to 12 and m is an integer of 1 to 3), and contains titanium oxide which has been treated while hydrolyzing in an aqueous system with a coupling agent represented by the following formula: ~ 1
0 μm. 2. The processing amount of said silicon oil or silicon varnish is 0.1 to 100 parts by weight of titanium oxide.
2. The toner according to claim 1, wherein the amount of the coupling agent is 5 to 30 parts by weight based on 100 parts by weight of the titanium oxide. 3. The method according to claim 1, wherein the titanium oxide has an average particle size of 0.01 to
3. The toner according to claim 1, wherein the toner has a hydrophobicity of 40 to 80% and a light transmittance at a wavelength of 400 nm of 40% or more.