JP2001083734A - Toner for developer and developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner having good triboelectric chargeability and fluidity without impairing the color reproducibility and transparency of a full-color image, also having good cleanability, preventing toner filming and giving a clear image free from image fog and traces of toner filming and having sufficient image density. SOLUTION: Fine resin particles obtained by polymerizing a monomer with crystalline titanium dioxide are added as an external additive together with silica to toner matrix particles. The transferability of the external additive is enhanced to diminish a residual toner on a photoreceptor after transfer, cleanability is enhanced to reliably remove the residual toner and the surface of the photoreceptor is refreshed by the polishing effect of the fine resin particles themselves to prevent defective cleaning and toner filming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer toner and a developer used for developing printers, electrophotographic apparatuses, and the like.

[0002]

2. Description of the Related Art In an electrophotographic apparatus or an electrostatic recording apparatus, a toner and a carrier for visualizing an electrostatic latent image formed on an electrostatic image holding member from a photoreceptor or a dielectric are used. In general, a toner used in a two-component developing method using a component developer is prepared by melt-mixing a colorant and other additives in a thermoplastic resin, uniformly dispersing the resultant, and then pulverizing and classifying a solidified product. It is manufactured as colored fine particles having a particle size of In recent years, in electrophotographic devices or electrostatic recording devices, the development from monocolor to full color has progressed,
In general, all colors are reproduced using three color toners of three primary colors, yellow toner, cyan toner, and magenta toner.

In general, in a two-component developer, toner is charged to a required charge amount and charge polarity by friction with a carrier, and is attracted to an electrostatic latent image using electrostatic attraction to develop the toner. Therefore, it is necessary that the toner has good triboelectric charging characteristics determined by the relationship with the carrier.

Further, a full-color toner is required to have excellent transfer characteristics since a multicolor image is reproduced by superimposing toners of respective colors. The transfer characteristics are greatly related to the charge amount of the toner. If the charge amount of the toner is too high, the adhesion of the toner to the photoreceptor becomes strong and the transferability decreases, and the transfer is performed even if the toner charge amount distribution is broad. Sex is reduced. Conversely, if the charge amount of the toner is too low, the toner scatters and the inside of the device is stained, or the image becomes unclear and turbid as a fog on a non-image portion of the support or as a mixed color with another image portion. Would.

In particular, color toners such as yellow toner, cyan toner and magenta toner do not contain conductive substances such as magnetic powder and carbon black like black toner. Therefore, the amount of charge of the toner tends to increase without being stabilized. The charge is easily affected by temperature and humidity, causing problems such as excessive charge under low humidity and insufficient charge under high humidity, making it difficult to maintain a stable charge in all environments. Met.

[0006] To solve the above problem, as a means for imparting charge stability, fluidity, durability stability and the like to the toner of a two-component developer, fine particles called an external additive are conventionally added to the surface of the toner base particles. are doing. In the case of a color toner, it is known that as a conductive substance such as carbon black of a black toner, metal oxide fine particles such as titanium oxide which do not affect the hue of the toner are used as an external additive.

[0007] As an example of using titanium oxide as an external additive, Japanese Patent Application Laid-Open No. 48-47345 discloses an abrasive,
JP-A-52-19535, JP-A-56-1289
JP-A-56-1854 discloses a fluidizing agent as a fluidizing agent.
No. 05 and JP-A-58-216252 disclose a surface-treated titanium oxide for imparting positive chargeability.
JP-A-1157 and JP-A-60-136755 disclose a charge control agent and the like for suppressing the charge amount of silica when used in combination with hydrophobic silica. JP-A-60-11205
No. 2, JP-A-5-188633, anatase-type titanium oxide, JP-A-59-52255, an alkyltrialkoxysilane-treated titanium oxide, and JP-A-7-24497, a rutile-type oxide. Titanium and the like are disclosed.

[0008]

However, when titanium oxide is applied to a color toner as an external additive, the amount of charge of the titanium oxide particles themselves is larger than that of other particles, and the adhesion is high. The toner is not easily transferred and easily remains as a residual toner on the photosensitive member. If the residual toner remains on the photoreceptor, the titanium oxide has a very small particle size of about 10 nm, and is hardly scraped off by the cleaning blade in the cleaning process. There is a problem that subsequent steps such as static elimination, charging, and exposure are adversely affected. Further, when wax or the like is included as an external additive, toner filming occurs on the drum surface while image formation is continued, and thus toner filming marks are formed on the formed image, and the display quality is significantly reduced. There was also a problem.

In view of the foregoing, the present invention has been made to solve the above-mentioned problems, and it is possible to obtain stable charging characteristics and durability stability in a full-color image without impairing color reproducibility and transparency regardless of the environment such as temperature and humidity. To provide a toner and a developer for a developer capable of preventing fogging and scattering of toner to the periphery, preventing defective cleaning of a photoconductor and toner filming, and obtaining a clear and good full-color image. Aim.

[0010]

According to the present invention, as a means for solving the above-mentioned problems, toner base particles containing a binder resin and a colorant, and externally added to the toner base particles in the presence of crystalline titanium oxide The present invention provides a toner for developer having fine resin particles obtained by polymerizing a raw material monomer and hydrophobic silica externally added to the toner base particles.

In order to solve the above-mentioned problems, the present invention provides toner base particles containing a binder resin and a colorant, and polymerization of raw material monomers in the presence of crystalline titanium oxide which is externally added to the toner base particles. The developer toner having fine resin particles obtained by performing the above and hydrophobic silica externally added to the toner base particles, before and after external addition of the fine resin particles and the hydrophobic silica, The ratio B / A of the 50% average diameter A corresponding to 50% of the cumulative number of all toner particles and the 10% average diameter B corresponding to 10% as the number particle size distribution with respect to the equivalent circle diameter after the 40-80%, 3 after external addition
0% or less, and a developer having a circularity of 0.85 or less is 3.0% or less before external addition and 8.0% or less after external addition.

In order to solve the above-mentioned problems, the present invention provides toner base particles containing a binder resin and a colorant, and polymerization of raw material monomers in the presence of crystalline titanium oxide which is externally added to the toner base particles. In the developer toner having fine resin particles obtained by performing, and hydrophobic silica externally added to the toner base particles,
The number particle size distribution with respect to the equivalent circle diameter before and after external addition of the fine resin particles and the hydrophobic silica is 50% corresponding to 50% of the cumulative number of all toner particles.
The ratio B /% of the% average diameter A to the 10% average diameter B corresponding to 10%
A is 40-80% before external addition and 5-2 after external addition.
5%, and a ratio of a circularity of 0.85 or less is 3.0% or less before external addition and 1.0 to 6.0% after external addition.

[0013] The present invention also provides, as a means for solving the above-mentioned problems, toner base particles containing a binder resin and a colorant, and polymerization of the raw material monomer in the presence of crystalline titanium oxide which is externally added to the toner base particles. The present invention provides a developer having fine resin particles obtained by performing the above, hydrophobic silica externally added to the toner base particles, and a silicone resin-coated carrier.

In order to solve the above-mentioned problems, the present invention provides toner base particles containing a binder resin and a colorant, and polymerization of raw material monomers in the presence of crystalline titanium oxide which is externally added to the toner base particles. In a developer having fine resin particles obtained by performing the above, hydrophobic silica externally added to the toner base particles, and a silicone resin-coated carrier, before externally adding the fine resin particles and the hydrophobic silica, And the ratio B / A of the 50% average diameter A corresponding to 50% of the cumulative number of all toner particles and the 10% average diameter B corresponding to 10% as the number particle size distribution with respect to the circle equivalent diameter after external addition. 40-80 before external addition
%, A developer having a circularity of 0.85 or less after external addition is 3.0% or less before external addition and 8.0% or less after external addition.

Further, the present invention provides a means for solving the above-mentioned problems, in which toner base particles containing a binder resin and a colorant, and polymerization of a raw material monomer which is externally added to the toner base particles in the presence of crystalline titanium oxide. In a developer having fine resin particles obtained by performing the above, hydrophobic silica externally added to the toner base particles, and a silicone resin-coated carrier, before externally adding the fine resin particles and the hydrophobic silica, And the ratio B / A of the 50% average diameter A corresponding to 50% of the cumulative number of all toner particles and the 10% average diameter B corresponding to 10% as the number particle size distribution with respect to the circle equivalent diameter after external addition. 40-80 before external addition
%, The ratio of the circularity of 0.85 or less after the external addition is 3.0% or less before the external addition and 1.0 to 6.0% after the external addition. provide.

Accordingly, the present invention provides a good and stable triboelectric charging regardless of the temperature and humidity environment by externally adding fine resin particles comprising a monomer containing crystalline titanium oxide to toner base particles. A good image quality can be obtained, a sufficient image density can be obtained, and fouling and fogging due to toner scattering can be prevented, and the cleaning property of the photoconductor is improved, and further, toner filming is prevented to obtain a clear and high quality color image. Things.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described. The present invention provides a toner having a stable triboelectric charge regardless of environment by polymerizing crystalline titanium oxide with a monomer to form fine resin particles and substantially increasing the particle size of the crystalline titanium oxide. To reduce residual toner on the photoreceptor, improve the cleaning performance of the toner remaining on the photoreceptor, and further effectively polish the photoreceptor surface to effectively scrape off toner filming. Things.

Next, an embodiment of the present invention will be described.
First, fine resin particles obtained by polymerizing crystalline titanium oxide with a monomer are, for example, various kinds of emulsion polymerization, soap-free emulsion polymerization, suspension polymerization, and the like in the presence of fine particles of crystalline titanium oxide. It is produced by a polymerization method. The soap-free emulsion polymerization method is a formulation in which an emulsifier is removed from an emulsion polymerization system.Initiator radicals generated in the aqueous phase combine with slightly soluble monomers in the aqueous phase, and the insoluble fine resin particles are eventually dissolved. Form. The fine resin particles produced by this polymerization method are generally preferred because they have a narrower particle size distribution than the emulsion polymerization method.

The size of the fine resin particles is such that the average particle size is 0.1.
Those having a thickness of 1 to 2.0 μm, preferably 0.2 to 1.0 μm are used. If the particle size of the fine resin particles is small, the crystalline titanium oxide is not sufficiently dispersed in the fine resin particles during polymerization. On the other hand, if the particle diameter of the fine resin particles is large, it is difficult to uniformly attach the resin particles to the surface of the toner base particles.

The crystalline titanium oxide includes rutile type, anatase type and rutile / anatase mixed type, and the production method is also classified into a dry method and a wet method. Among them, the rutile / anatase mixed type is synthesized by a dry method. Anatase-rich rutile / anatase mixed titanium oxide is preferred.

It is preferable that the fine resin particles contain 10% to 50% by weight of crystalline titanium oxide based on 100% by weight of the raw material monomer. If the amount of the crystalline titanium oxide is small, the original effect of dispersing the crystalline titanium oxide in the fine resin particles cannot be obtained. If the amount of crystalline titanium oxide is large, sufficient dispersibility cannot be secured.

The material used as the raw material monomer for the fine resin particles is not particularly limited, and homopolymers or copolymers of various vinyl monomers exemplified below and polymer blends thereof may be used. It is preferable to use a styrene-based polymer or a styrene-methacryl-based polymer.

Examples of the vinyl monomer include styrene, o-methylstyrene, m-methylstyrene, p-
Methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert-
Butylstyrene, pn-hexylstyrene, pn-
Octylstyrene, pn-nonylstyrene, pn-
Styrene such as decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, and derivatives thereof are mentioned, and among them, styrene is most preferred.

Other vinyl monomers include, for example,
Vinyl acetate, vinyl propionate, vinyl benzoate,
Vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-acrylate
Octyl, dodecyl acrylate, 2-ethylhexyl acrylate, steanyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-methyl methacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate Α-ethylene aliphatic monocarboxylic acid esters such as isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate , Acrylonitrile, methacrylonitrile, (meth) acrylic acid derivatives such as acrylamide, vinyl ethers such as vinyl ethyl ether, vinyl methyl ketone, vinyl hex Vinyl ketones such as silketone and methyl isopropenyl ketone, N-vinylpyrrole, N
-N-vinyl compounds such as vinylcarbazole, N-vinylindole and N-vinylpyrrolidone, and vinylnaphthalenes.

In the present invention, the fine resin particles may contain an offset preventing agent. Examples of the anti-offset agent to be contained in the fine resin particles include polyolefin-based wax, for example, low molecular weight polypropylene, low molecular weight polyethylene, oxidized polypropylene, oxidized polyethylene, and the like.

In addition, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, plant waxes such as candelilla wax, carnauba wax, rice wax, water wax, jojoba oil, petroleum waxes such as paraffin wax and petrilactam, and montan Synthesis of modified waxes such as wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives, silicone oils such as dimethyl silicone oil and phenylmethyl silicone oil, and other various fatty acids, acid amides, acid imides, esters, and ketones. If it is a wax, it may be used together with a mixture of these various waxes.

The amount of the wax component, which is an anti-offset agent, added to the fine resin particles is 0.1 to 20 parts by weight, more preferably 1 to 15 parts by weight, per 100 parts by weight of the fine resin particles.
Parts by weight. If the amount of the wax component is small, the effect as an offset preventing agent cannot be obtained. On the other hand, if the added amount of the wax component is large, sufficient dispersion cannot be performed, and an excessive amount of the wax component is eluted, and when added to the toner, the storage stability of the toner is reduced, or the surface of the photoconductor is filled during development. And the display quality is degraded.

In the present invention, the fine resin particles may contain a charge control agent. Examples of the charge control agent to be contained in the fine resin particles include negative polarity control agents such as metal chelates of alkyl salicylic acid, chlorinated polyesters, polyesters with excess acid groups, chlorinated polyolefins, metal salts of fatty acids, and fatty acid soaps. .

The amount of the charge control agent added to the fine resin particles is
0.001 to 10 based on 100 parts by weight of the fine resin particles
Parts by weight, preferably 0.01 to 5 parts by weight. If the amount is small, the effect as a charge control agent cannot be obtained.
If the addition amount is large, the charge control agent may peel off from the fine resin particles and contaminate the surface of the carrier, or may be mixed in the developer and impair the charge stability during long-term use.

As an external additive to the toner base particles,
In addition to the fine resin particles containing crystalline titanium oxide in the monomer of the present invention, silica fine particles, metal oxide fine particles, a cleaning aid and the like are used. Examples of the silica fine particles include silicon dioxide, aluminum silicate, sodium silicate, potassium silicate, zinc silicate, and magnesium silicate. Examples of the metal oxide fine particles include zinc oxide, titanium oxide, aluminum oxide, zirconium oxide, strontium titanate, and barium titanate.

Examples of the cleaning aid include fine resin powders such as polymethyl methacrylate, polyvinylidene fluoride and polytetrafluoroethylene. These external additives may have been subjected to a surface treatment such as hydrophobicization. As a means for mixing the external additives,
Although a known mixing device can be used, for example, it is desirable to use a high-speed flow type mixing device. Examples of the high-speed fluid mixer include a Henschel mixer, a super mixer, and a micro speed mixer. Alternatively, a hybridizer, a homogenizer, a kryptron system, a turbo mill, or the like may be used.

The toner base particles serving as the core agent to which the fine resin particles and the silica fine particles are externally added are produced by using a binder resin and a coloring agent, for example, as follows. First, at least 100 parts by weight of a binder resin and 1 to 10 parts by weight of a colorant are mixed and dispersed by using a high-speed fluid mixer such as a Henschel mixer. Next, the mixture is heated and melt-kneaded using a pressure kneader, a roll or the like. The obtained mixture is roughly pulverized using a hammer mill, a jet mill or the like. Then, after fine pulverization using a jet mill or the like,
Several μm to several tens μm of toner base particles by air classification
The toner of the present invention is obtained by classifying into a desired particle size of about m and mixing with an external additive by a high-speed fluidizing mixer or the like.

As the binder resin, there can be used a copolymer of styrene and its substituent or an acrylic resin which has been conventionally used as a binder resin for toner base particles. Examples of the copolymer of styrene and its substituted product include, for example, polystyrene homopolymer,
Hydrogenated styrene resin, styrene-isobutylene copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene-styrene terpolymer, acrylonitrile-styrene-acrylic ester terpolymer, styrene-acrylonitrile copolymer, Acrylonitrile
Acrylic rubber-styrene terpolymer, acrylonitrile-chlorinated polystyrene-styrene terpolymer, acrylonitrile-EVA-styrene terpolymer, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer Styrene-butadiene rubber, styrene-maleic acid ester copolymer, styrene-isobutylene copolymer, styrene-maleic anhydride copolymer and the like.

As the acrylic resin, for example,
Polyacrylate, polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, polyglycidyl methacrylate, polyfluorinated acrylate, styrene-methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-ethyl acrylate copolymer And the like.

In addition, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, phenol resin, urea resin, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, aliphatic Alternatively, an alicyclic hydrocarbon resin, an aromatic petroleum resin, chlorinated paraffin, paraffin wax, or the like can be used alone or as a mixture.

As the coloring agent, organic or inorganic pigments or dyes are used. For example, First Yellow G, Benzidine Yellow, Indofast Orange,
Irgazine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Lisor Red 2
G, lake red C, rhodamine FB, rhodamine B lake, phthalocyanine blue, pigment blue, brilliant green B, phthalocyanine green, quinacridone, and the like can be used, and these can be used alone or in combination.

The toner base particles after the classification have a particle diameter corresponding to a cumulative number of all toner base particles of 50%.
The ratio B / A of the 0% average diameter A and the 10% average diameter B which is the particle diameter corresponding to the cumulative number of 10% is 40 to 80%, preferably 55 to 75%, and the circularity is 0.85 or less. (Refer to the number% of particles having a circularity of 0.85 or less).
0% or less, preferably 0.5 to 3.0%.

The ratio of 50% average diameter A to 10% average diameter B, B /
The fact that A is large means that the particle size distribution is narrow as shown in FIG. 1, for example, and that the ratio B / A is small is that the particle size distribution is wide as shown in FIG. Means that there are many.

When B / A is less than 40%, the ratio of fine particles, particularly particles having a particle size of 5 μm or less, becomes extremely large.
In this case, when the toner is developed and adheres to the photoconductor,
Microparticles have a higher charge amount of the particles than others and have high adhesion, so they are not easily transferred to transfer paper during transfer,
The toner remains on the photoconductor as residual toner. Since such fine particles are not easily scraped off by the cleaning blade even in the cleaning step, they adversely affect subsequent steps such as charge removal, charging, and exposure. Further, when such fine particles contain an additive such as wax, the content is relatively larger than that of other particles. Come out (drum film mink)
Etc. appear as deterioration of display quality.

On the other hand, when the ratio B / A exceeds 80%, it is difficult to control the production conditions, the production yield is remarkably reduced, and the cost is undesirably increased. Next, when the circularity is 1.0
Means that the shape of the toner is circular, that is, spherical. A circularity of 0.85 or less means that the shape of the toner is extremely irregular, and is close to an elliptical sphere. When the shape of the toner particles is extremely irregular, the fluidity decreases and the degree of aggregation increases. Such a toner cannot be subjected to development and, even if developed, does not have long-term durability. In addition, the toner tends to be crushed by friction and impact between the toner and the developing device member, and the fine particles tend to increase. Therefore, the proportion of particles having a circularity of 0.85 or less should be as small as possible and should be 3.0% or less.

However, after the external additive containing the fine resin particles is mixed with the toner base particles, the cumulative number of all toner particles is 50% average diameter A corresponding to 50% and the cumulative number is 10%. %, Which is the particle diameter corresponding to 10%
Ratio B / A of 30% or less, preferably 5 to 25%, and the ratio of circularity of 0.85 or less should be 8.0% or less, preferably 1.0 to 6.0%. Good.

When the toner base particles are mixed with the external additive containing the fine resin particles of the present invention, the particle size distribution based on the number of all the toner particles to be a mixture is determined by the toner base particles and the external additive particles. Is the sum of the respective particle size distributions, and a distribution having a peak of each particle size. That is, for example, as shown in FIG. 3, the particle size distribution has a peak of two or more particle sizes, and the apparent particle size distribution has a broader shape with smaller particle size, indicating that the number of fine resin particles is large. .

However, the fine resin particles containing crystalline titanium oxide in at least the monomer of the present invention are relatively flexible and have low adhesiveness, so that they do not damage the photosensitive member, the electrostatic recording member, and the cleaning blade. If the ratio B / A of the 50% average diameter A to the 10% average diameter B is less than 30%, it is possible to increase the cleaning efficiency, prevent toner filming, and obtain an image with high display quality over a long period of time. good.

The toner base particles before mixing the external additives are
When the external additive of the present invention is mixed, the circularity distribution based on the number of all the toner particles to be a mixture is such that the external additive particles are adhered and mixed on the surface of the toner base particles, and the circularity is apparent. Lower, indicating that irregular particles increased. However, the fine resin particles containing crystalline titanium oxide in at least the monomer of the present invention attached to the surface of the toner base particles are relatively flexible and have low adhesion, and thus damage the photoconductor, the electrostatic recording medium, and the cleaning blade. Cleaning efficiency can be increased without causing toner contamination, and a high-quality image can be obtained over a long period of time. It may be more. However, as little as possible is better, and it must be 8.0% or less.

The toner of the present invention thus obtained is
It can be applied to all known developing methods. For example, a cascade method, a magnetic brush method, a two-component developing method such as a microtoning method, a conductive one-component developing method, an insulating one-component developing method,
Non-magnetic one-component development, such as a one-component development method containing a magnetic substance, such as a jumping development method, a powder cloud method, a fur brush method, and being conveyed to a developing unit by being electrostatically held on a toner carrier and developed. The law can be raised.

Next, a production example of crystallized titanium oxide contained in the fine resin particles will be described. The crystallized titanium oxide is not limited to this.

(Production Example 1 of Titanium Oxide) A mixed gas of 2% by volume of titanium tetrachloride, 4% by volume of hydrogen gas and 94% by volume of air vaporized at 150.degree.
Hydrolysis is performed by burning at 00 to 800 ° C, and the reaction product is immediately cooled at a temperature of 100 ° C for 30 seconds. As a result, crystalline titanium dioxide A having an average primary particle diameter of 15 nm and shown in (Table 1) was obtained. This titanium dioxide A
Was 10% rutile type and 90% anatase type.

(Production Example 2 of Titanium Oxide) To a 0.5 mol / L aqueous solution of titanium tetrachloride, ammonium water was added at room temperature until the pH reached 3.5, followed by heating to 80 ° C. For 30 minutes to obtain a neutralized precipitate. Next, the precipitate was filtered and washed, and the obtained cake was dispersed again in water to form a slurry, and the pH of the slurry was adjusted to 7.0 by adding ammonium water. Then, it was filtered, washed and dried at a temperature of 110 ° C. The obtained dried product was fired at 530 ° C. for 1 hour to obtain crystalline titanium dioxide B having an average primary particle diameter of 15 nm and shown in (Table 1). The crystal form of this titanium dioxide B was rutile type 80% and anatase type 20%.

(Production Example 3 of Titanium Oxide) To a dispersion slurry of orthotitanic acid having a titanium dioxide concentration of 60 g / liter, 40% by weight of hydrochloric acid based on titanium dioxide was added, followed by heating to the boiling point and holding for 3 hours. After that, it was washed by filtration.
The obtained cake was dried at a temperature of 110 ° C., baked at 800 ° C. for 1 hour, pulverized with an Ishikawa-type rai mill, and crystallized with a mean primary particle diameter of 0.010 μm as shown in Table 1 below. Titanium C was obtained. The crystal form of this titanium dioxide C was 100% rutile.

[Table 1] Next, a production example of fine resin particles obtained by polymerizing crystalline titanium oxide with a monomer will be described. The fine resin particles are not limited to these.

(Production Example 1 of Fine Resin Particles) 80 parts of methyl methacrylate, 20 parts of butyl methacrylate, 200 parts of distilled water, and 20 parts of titanium oxide A shown in (Production Example 1 of titanium oxide) in a four-neck flask having a capacity of 5 liters And 0.6 parts of potassium persulfate, 4 parts of polyoxyethylene nonylphenyl, and 1 part of sodium lauryl saalphenol were added as initiators, and a thermometer, a stainless steel stirring rod,
A falling condenser and a nitrogen inlet tube were attached, and the emulsion polymerization reaction was carried out at 80 ° C. for 4 hours in a nitrogen gas stream.
℃, filtered and dried, average particle size 0.1μm
Of fine resin particles A according to the present invention. The glass transition point of the fine resin particles A was 108 ° C.

(Preparation Example 2 of Fine Resin Particles) Fine resin particles B having an average particle diameter of 0.1 μm were obtained in the same manner as in (Preparation Example 1 of fine resin particles) except that titanium oxide A was not added.

(Production Example 3 of Fine Resin Particles) In the same apparatus as in (Production Example 1 of Fine Resin Particles), 0.3 parts of 2,2′-azobis (2-amidinopropane) dibasic acid and 8 parts of distilled water were added.
00 parts, methyl methacrylate 200 parts, titanium oxide B
20 parts were added, and the emulsion polymerization reaction was carried out at 70 ° C. for 3 hours in a nitrogen gas stream. Thereafter, the liquid temperature was cooled to 20 ° C., followed by filtration and drying to obtain fine resin particles of the present invention having an average particle diameter of 0.4 μm. C was obtained. The glass transition point of the fine resin particles C is 105
° C.

Next, a production example of toner base particles will be described. The toner base particles are not limited to these.

(Toner Base Particle a) Polyester Resin 10
0 parts by weight, 5 parts by weight of a phthalocyanine pigment, 2 parts by weight of a gold-containing dye, and 5 parts by weight of a natural wax are preliminarily mixed with a Henschel mixer, heated and melt-kneaded with an extruder, cooled, pulverized with a jet mill, and then classified with an air classifier. The toner base particles a having a volume average particle diameter of 8 μm and a particle diameter of 4 to 14 μm were obtained. As shown in Table 2, the particle size distribution and the circularity distribution of the toner base particles a were such that the 50% average diameter A was 7.0 μm.
m, 10% average diameter B is 4.6 μm, ratio B / A is 65.7.
%, And the ratio of circularity of 0.85 or less was 1.36%.

(Comparative Toner Base Particles b) In (Toner Base Particles a), the volume average particle diameter was 8 μm by changing the pulverization and classification conditions.
m, and comparative toner base particles b having a particle size of 4 to 14 μm were obtained.
The particle size distribution and circularity distribution of the comparative toner base particles b are as follows:
As shown in (Table 2), the 50% average diameter A was 5.1 μm,
The 0% average diameter B was 1.3 μm, the ratio B / A was 25.4%, and the ratio of circularity was 0.85 or less was 5.54%.

Next, a toner in which an external additive is added to the above toner base particles will be described.

(Toner A) Toner A was obtained by mixing 1.0 part by weight of fine resin particles A and 2.5 parts by weight of hydrophobic silica with 100 parts by weight of toner base particles a by a high-speed mixer. As shown in Table 2, the particle size distribution and the circularity distribution of the toner A are such that the 50% average diameter A is 5.7 μm and the 10% average diameter B
Is 0.8 μm, the ratio B / A is 14.0%, and the circularity is 0.85.
The following ratio was 4.91%.

(Toner B) Toner B was obtained by mixing 1.0 part by weight of fine resin particles C and 2.5 parts by weight of hydrophobic silica with 100 parts by weight of toner base particles a by a high-speed mixer. As shown in Table 2, the particle size distribution and the circularity distribution of the toner B are such that the 50% average diameter A is 6.2 μm and the 10% average diameter B is
Is 0.8 μm, the ratio B / A is 12.9%, and the circularity is 0.85.
The following ratio was 3.09%.

(Toner C) 200 g of the fine resin particles A are placed in a separable flask having a content of 5 liters, and while mixing, 20 g of hexyltrimethoxysilane is mixed well in a nitrogen gas atmosphere. The temperature was lowered to obtain hydrophobic treated fine resin particles A ′ having a hydrophobicity of 70%. Thereafter, 0.5 parts by weight of the hydrophobic fine resin particles A ′ and 2.5 parts by weight of hydrophobic silica are mixed with 100 parts by weight of the toner base particles a by a high-speed mixer, and the toner C is mixed.
I got The particle size distribution and circularity distribution of this toner C are as follows:
As shown in (Table 2), the 50% average diameter A was 6.2 μm,
The 0% average diameter B was 1.4 μm, the ratio B / A was 22.5%, and the ratio of circularity was 0.85 or less was 2.26%.

(Toner D) In (Toner C), titanium oxide B is used instead of fine resin particles A containing titanium oxide A.
Was similarly subjected to hydrophobic treatment to obtain hydrophobic treated fine resin particles C ′ having a degree of hydrophobicity of 65%. In the same manner, toner D was obtained. The particle size distribution and the circularity distribution of the toner D are as shown in Table 2 and the 50% average diameter A
Is 6.2 μm, 10% average diameter B is 0.8 μm, ratio B / A
Was 12.9% and the ratio of circularity 0.85 or less was 3.09%. (Comparative Toner E) (Example 1)
Comparative toner E was obtained in the same manner as in (Example 1) except that fine resin particles B containing no titanium oxide were used instead of fine resin particles A containing. As shown in Table 2, the particle size distribution and the circularity distribution of the comparative toner E were as follows: 50% average diameter A was 1.4 μm, 10% average diameter B was 0.8 μm, and the ratio B /
A is 57.1% and the ratio of circularity is 0.85 or less 6.42%
It became.

(Comparative Toner F) (Example 1)
Example 1 except that comparative toner base particles b were used instead of toner base particles a, and titanium oxide C having 100% rutile crystal was used instead of fine resin particles A containing titanium oxide A.
(Comparative Toner F) was obtained in the same manner as described above. As shown in Table 2, the particle size distribution and the circularity distribution of the comparative toner F are as follows: 50% average diameter A is 8.1 μm, and 10% average diameter B is 0.8 μm.
μm, the ratio B / A was 9.9%, and the ratio of circularity was 0.85 or less was 6.28%.

[Table 2] Further, a ferrite having a particle diameter of about 50 μm coated with a silicone resin as a carrier was used for each of the toners A to F,
8 parts by weight of each of the above toners A to F were added to 100 parts by weight of the carrier, and then mixed by a V blender for 30 minutes to obtain each developer.

Each of the developers of Examples 1 to 3 and Comparative Example produced as described above was used by using a commercially available Toshiba copier (product name: Primage 251) having an image forming section shown in FIG. A copy test was performed. FIG. 4 is a schematic diagram showing the configuration of the image forming unit 10.
2. Exposure unit 13, developing device 14, transfer device 16, stripper 1.
7, the cleaning device 18 and the static eliminator 20 are sequentially arranged along the rotation in the direction of the arrow x.

The toner container 22 of the developing device 14 contains a developer 23 composed of toner and carrier.
A multi-pole magnet roll 24 is provided on the photosensitive drum 11 side.
And a developing sleeve 25 mounted on the outer periphery thereof. The carrier of the developer 23 adheres to the surface of the developing sleeve 25 by the magnetic force of the multipolar magnet roller 24,
The toner adheres to the carrier surface to form a toner layer. The multi-pole magnet roller 24 is fixed, the developing sleeve 25 is rotated in the direction of the arrow y, and the developer 23 is conveyed at any time according to this rotation.

The transport amount of the developer 23 is regulated by a regulating blade 26. Reference numeral 27 denotes a power source for applying a developing bias. The toner 23 adheres to the electrostatic latent image on the photosensitive drum 11 from the developing sleeve 25 by electrostatic attraction at a location where the photosensitive drum 11 and the developing sleeve 25 approach. Development takes place. Reference numerals 28 and 30 denote stirring rollers that stir and transport the developer 13 in the toner container 12 and frictionally charge the toner.

The cleaning device 18 has a cleaning blade 31 having elasticity and a toner auger 32 for conveying the residual toner collected by the cleaning blade 31.

Here, the charge amount of the toner was measured by a blow-off powder charge amount measuring device, Model TB-220, manufactured by Toshiba Chemical Corporation. The T / C concentration ratio, which is the concentration ratio of the toner to the carrier, was determined by measuring the weight when a certain amount of the developer was removed by blowing air. Image density was measured with a Macbeth densitometer. Flowability was measured by a powder tester. Environmental characteristics are low temperature and low humidity (10 ℃,
(20% RH), high temperature and high humidity (30 ° C., 80% RH), room temperature and room humidity (20 ° C., 50% RH). The toner scattering was evaluated by observing the area around the developing device inside the copying apparatus.

The copy test was performed on 10k sheets at low temperature and low humidity.
10k copies were made at high temperature and high humidity, and 30k copies were made at room temperature and room humidity.

The poor cleaning was evaluated by observing a thin ghost-like image formed on the formed image.

The toner filming was evaluated by observing toner spots and streaks generated when copying white paper.

As a result, the evaluation results as shown in Table 3 were obtained for the developers of Examples 1 to 3 and Comparative Example. In the evaluation, ○ means no problem at all, △ means somehow usable, and × means not usable.

[Table 3] That is, each of the developers of Examples 1 to 3 maintains a good charge amount from the initial stage of the toner to the end of a predetermined number of copies, and has good T / C density ratio, good image density, etc. In addition, a high display quality can be obtained, the surroundings are not stained by toner scattering, and the residual toner on the photoconductor 11 can be surely removed by the cleaning blade 31. As a result, toner filming on the surface of the photoconductor 11 can be achieved. It could be prevented and showed excellent characteristics.

On the other hand, since the fine resin particles B do not contain the titanium oxide A, the developer of the comparative example has an unstable charging characteristic, is inferior in fluidity due to silica, and is in an initial state of the toner. Although a good charge amount could be obtained and usable, the T / C density ratio decreased with an increase in the number of copies, and a sufficient image density could not be obtained. Cause contamination of the surrounding area,
Furthermore, ghost-like images due to poor cleaning are seen, and streaks due to toner filming occur.
Display quality has declined.

According to this structure, fine resin particles are formed by incorporating crystalline titanium oxide such as rutile / anatase mixed type titanium oxide A or titanium oxide B into a monomer body and externally added to toner base particles. By doing so, it is possible to increase the substantial particle size of the crystalline titanium oxide, improve the transferability, and improve the transferability as compared with the conventional case where crystalline titanium oxide is externally added as a simple substance. The residual amount on the surface of the photoconductor 11 can be reduced, and the toner remaining on the photoconductor 11 by the cleaning blade 31 can be reliably removed. As a result, toner filming on the photoconductor 11 can be prevented.

Since the fine resin particles have a polishing effect on the surface of the photoconductor 11 due to the enlargement of the particle size, even if toner filming occurs on the surface of the photoconductor 11 to some extent, it can be scraped off by polishing the amorphous resin particles. Further, toner filming can be prevented. Therefore, display quality is not deteriorated due to defective cleaning or traces of toner filming.
In addition, since the toner in the developer maintains stable triboelectric charging and good fluidity, it prevents image fogging and filming marks, has a sufficient image density, and may cause contamination due to toner scattering. Clear and good images can be obtained.

The present invention is not limited to the above-described embodiment, and can be variously changed in design. For example, the crystalline titanium oxide contained in the monomer may be a rutile type simple substance or an anatase type simple substance, or may be a rutile type titanium oxide. The mixing ratio of the anatase type and the anatase type is arbitrary, and the particle size of the fine resin is also optional as long as it can maintain good cleaning properties and can be uniformly added to the surface of the toner base particles.

[0075]

As described above, according to the present invention, stable triboelectric charging and good fluidity of a toner are impaired by externally adding fine resin particles containing crystalline titanium oxide to a monomer. Without any problem, the transferability of the toner is improved, the residual toner remaining on the surface of the photoreceptor after transfer is reduced, and the cleaning performance of the toner is improved, the residual toner is reliably removed, and the polishing effect of fine resin particles is further improved. To refresh the surface of the photoreceptor. Therefore, it is possible to prevent toner filming from occurring due to defective cleaning, prevent image deterioration due to toner filming marks, obtain a clear full-color image having a sufficient image density, and improve display quality.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing an example of a particle size distribution and an accumulated number when a ratio B / A of a 50% average diameter A and a 10% average diameter B of the particles of the embodiment of the present invention is large.

FIG. 2 is a characteristic diagram showing an example of a particle size distribution and an accumulated number when the ratio B / A of the 50% average diameter A and the 10% average diameter B of the particles according to the embodiment of the present invention is small.

FIG. 3 shows the particle size distribution and the cumulative number when the ratio B / A of the 50% average diameter A and the 10% average diameter B of all the particles obtained by mixing the toner base particles with the external additive is large in the embodiment of the present invention. FIG. 4 is a characteristic diagram showing an example.

FIG. 4 is a schematic configuration diagram showing an image forming unit of a copying machine used for a developer copy test according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Image forming part 11 ... Photoreceptor 12 ... Charging device 13 ... Exposure part 14 ... Developing device 16 ... Transfer device 17 ... Peeling device 18 ... Cleaning device 20 ... Removal machine 31 ... Cleaning blade

Claims (16)

[Claims] 1. A toner base particle containing a binder resin and a colorant, and fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, And hydrophobic silica externally added to the toner base particles. 2. A toner base particle containing a binder resin and a colorant, fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, And a hydrophobic silica externally added to the toner base particles, wherein the fine resin particles and the hydrophobic silica before and after externally added as a number particle size distribution with respect to a circle equivalent diameter, 50 corresponding to 50% of the cumulative number of all toner particles
The ratio B /% of the% average diameter A to the 10% average diameter B corresponding to 10%
A: 40-80% before external addition, 30% after external addition
A developer having a circularity of 0.85 or less, 3.0% or less before external addition, and 8.0% or less after external addition. 3. A toner base particle containing a binder resin and a colorant, and fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, In the developer toner having hydrophobic silica externally added to the toner base particles, the number particle size distribution with respect to the equivalent circle diameter before and after externally adding the fine resin particles and the hydrophobic silica, 50 corresponding to 50% of the cumulative number of toner particles
The ratio B /% of the% average diameter A to the 10% average diameter B corresponding to 10%
A is 40-80% before external addition and 5-2 after external addition.
5% and a ratio of circularity of 0.85 or less is 3.0% or less before external addition and 1.0 to 6.0% after external addition. 4. The developer toner according to claim 1, wherein the crystalline titanium oxide is a rutile / anatase mixed type titanium oxide. 5. The developer toner according to claim 1, wherein the raw material monomer is a vinyl monomer, and fine resin particles are obtained by soap-free emulsion polymerization. 6. With respect to 100% by weight of a raw material monomer,
Rutile / anatase mixed type titanium oxide 10% by weight to 5%
The developer toner according to claim 5, wherein 0% by weight is contained. 7. The fine resin particles have an average particle diameter of 0.1 to 0.1.
The developer toner according to claim 1, wherein the thickness of the toner is 2 μm. 8. The fine resin particles have a glass transition temperature of room temperature or higher, and are based on 100% by weight of the toner base particles.
The toner for a developer according to claim 7, wherein the toner is contained in an amount of 0.1 to 3.0% by weight. 9. A toner base particle containing a binder resin and a colorant, and fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, A developer comprising: hydrophobic silica externally added to toner base particles; and a carrier coated with a silicone resin. 10. A toner base particle containing a binder resin and a colorant, and fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, In a developer having hydrophobic silica externally added to toner base particles and a silicone resin-coated carrier, the number particle size with respect to the circle equivalent diameter before and after externally adding the fine resin particles and the hydrophobic silica As a distribution, 50 corresponding to 50% of the cumulative number of all toner particles
The ratio B /% of the% average diameter A to the 10% average diameter B corresponding to 10%
A: 40-80% before external addition, 30% after external addition
A developer having a circularity of 0.85 or less before and 3.0% or less after external addition and 8.0% or less after external addition. 11. A toner base particle containing a binder resin and a colorant, fine resin particles externally added to the toner base particle and obtained by polymerizing a raw material monomer in the presence of crystalline titanium oxide, In a developer having hydrophobic silica externally added to toner base particles and a silicone resin-coated carrier, the number particle size with respect to the circle equivalent diameter before and after externally adding the fine resin particles and the hydrophobic silica As a distribution, 50 corresponding to 50% of the cumulative number of all toner particles
The ratio B /% of the% average diameter A to the 10% average diameter B corresponding to 10%
A is 40-80% before external addition and 5-2 after external addition.
5%, wherein the ratio of circularity of 0.85 or less is 3.0% or less before external addition and 1.0 to 6.0% after external addition. 12. The method according to claim 9, wherein the crystalline titanium oxide is a rutile / anatase mixed type titanium oxide.
The developer according to any one of claims 1 to 11. 13. The developer according to claim 9, wherein the raw material monomer is a vinyl monomer and fine resin particles are obtained by soap-free emulsion polymerization. 14. Rutile / anatase mixed type titanium oxide 10% by weight based on 100% by weight of raw material monomer
2. The composition according to claim 1, wherein the content is about 50% by weight.
4. The developer according to 3. 15. The fine resin particles have an average particle diameter of 0.1.
15. The structure according to claim 9, wherein the thickness is about 2 μm.
The developer according to any one of the above. 16. The fine resin particles have a glass transition temperature of room temperature or higher and have a glass transition temperature of 100% by weight based on the toner base particles.
The developer according to claim 15, wherein the developer is contained in an amount of 0.1 to 3.0% by weight.