JP2001117265A - Electrophotographic toner, its production and method of forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner and a method of forming an image having excellent developing property and durability which are key factors for a toner of a small particle size and which hardly causes contamination on the base or filming. SOLUTION: The electrophotographic toner is prepared by adding an additive to the mother toner consisting of at least a binder resin and a coloring agent, and the toner has 4.0 to 9.0 μm weight average particle diameter Dv. As for the additive, titania having 2 to 12 aspect ratio is used, and the isolation degree of the titania is 0.5 to 8%. The ratio of Dv to the number average particle diameter Dn satisfies Dv/Dn<=1.3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner applied to an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like. The present invention relates to an electrophotographic toner which is excellent and has less occurrence of background stain and filming, and a method for producing the same and an image forming method.

[0002]

2. Description of the Related Art A conventional electrophotographic method is disclosed in US Pat.
No. 7691, JP-B-42-23910 and JP-B-43-24748, etc., various methods are described. In general, a photoconductive substance is used, and the photoconductive material is formed on a photoconductive support by various means. An electric latent image is formed and then the latent image is developed with toner to obtain a visible image, or, if necessary, a powder image is transferred to paper or the like and then fixed by heating / pressing or solvent vapor. To obtain a visible image.

In recent years, with the rapid spread of OA equipment such as copying machines, facsimile machines and printers using electrophotography,
Demands for higher image quality, higher reproducibility, higher stability, and the like are higher than ever before. On the other hand, it is often practiced to improve the image quality by reducing the particle size of the toner.

Although it is effective to reduce the particle size of the toner to improve the image quality, the charge amount per unit weight is increased, so that the developability is reduced, and the image density is reduced and the durability is reduced. Is likely to deteriorate.

In addition, as the particle size of the toner becomes smaller, the dispersibility of each component of the toner tends to deteriorate, whereby the distribution of the charge amount of the toner becomes uneven and wide, and the non-uniformity of the photoreceptor and the intermediate transfer member is reduced. The amount of toner adhering to the image portion increases, which causes the background stain to increase.

Furthermore, the smaller the particle size of the toner, the stronger the cohesiveness of the toner becomes, thereby lowering the fluidity. Also, in the development of a solid portion, when the coagulated toner is present on a photoreceptor, an intermediate transfer member, etc. Is difficult to be transferred around the aggregated toner, which is likely to cause transfer unevenness and white spots.

In particular, in the case of a color toner, the image area of a document used for copying is generally larger than that of a conventional toner, and a solid image such as a photograph, a catalog, a map, or a painting is also formed on a document. Since there are many cases, the transfer unevenness and white spots greatly deteriorate image quality.

On the other hand, inorganic oxides such as silica and titania are often used as additives used in toners for the purpose of imparting fluidity and heat-resistant storage stability. However, the loose additive that has weak adhesion to the base toner or is not adhered easily migrates onto the photoconductor together with the toner when the electric latent image formed on the photoconductor is developed by the toner, It is often observed that an image remains on the photoconductor after being transferred from the photoconductor to a transfer material such as paper and adheres to the photoconductor without being cleaned. When these additives accumulate on the photoreceptor, filming occurs on the photoreceptor, causing image defects and a decrease in image density of the toner image transferred to the transfer material, resulting in poor durability. In addition, the surface of the photoreceptor may be damaged, thereby shortening the life of the photoreceptor. When an electric latent image on a photoreceptor is developed with toner, these additives may spill out of the developing device and contaminate the inside of a copying machine. The tendency becomes particularly remarkable because the additive becomes difficult to adhere to.

Further, as the toner particle size becomes smaller, the specific surface area of the toner increases, so that it is necessary to increase the amount of the additive. However, this also increases the amount of the free additive.
It causes filming on the photoreceptor and contamination in the apparatus.

[0010] Further, such a toner having a weak adhesion of an additive has a large change in the adhesion state from the initial state when subjected to stress in the developing device. The toner and the charge level are different, and background stain and image density decrease are likely to occur.

On the other hand, if the adhesion to the base toner is too strong, the additive is embedded in the toner, the proportion of fine particles which can function effectively decreases, and the fluidity also decreases. Therefore, in order to obtain desired toner characteristics, it is necessary to further increase the amount of addition. However, excessive addition increases the amount of unadhered and released additives, so that the ratio of migration to the photoreceptor and adhesion increases, and This causes factors such as filming of the photoconductor, image defects, and a decrease in durability.

In order to solve the above problems, it is conceivable to increase the molecular weight of the binder resin so that the additive is not embedded. However, in the case of a black toner, this lowers the low-temperature fixability, and in the case of a color toner, it increases the heat-fusibility at the time of fixing and heating, lowers the viscosity, and lowers the gloss and transparency of the black toner. However, a resin having a high molecular weight has a high softening temperature, and even if the fixing temperature is set high, the viscosity does not decrease, and sufficient gloss and transparency cannot be obtained.

For the reasons described above, the toner having a small particle size has excellent developing properties and durability, which are particularly remarkable.
At present, no electrophotographic toner has been obtained with less occurrence of background staining and filming.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art. More specifically, the present invention is excellent in developability and durability, which are problems in a toner having a small particle diameter, and furthermore, it is possible to prevent background contamination and the like. An object of the present invention is to provide an electrophotographic toner with less occurrence of filming and the like, a method of manufacturing the same, and an image forming method.

[0015]

SUMMARY and effects of the Invention The present invention, at least a binder resin, electrophotographic weight average comprising additive was added to the mother toner comprising a colorant diameter D _V is 4.0~9.0μm The toner for use in the present invention is characterized in that at least titania having an aspect ratio of 2 to 12 is used as an additive, and the liberation of titania is 0.5 to 8%.

The toner for electrophotography of the present invention is characterized in that at least titania having an aspect ratio of 2 to 12 is used as an additive, and the aspect ratio is particularly preferably 5 to 10.

Titania having an aspect ratio of 2 to 12 has a higher specific surface area than spherical titania, so that the probability of contact with the base toner increases, and the contact area increases. As a result, fluidity is improved, and background dirt and toner scattering are reduced.

Further, since the adhesion is improved, the contact between the base toner having high adhesiveness and the photoreceptor, the developing roller, the carrier and the sleeve is suppressed, so that the filming and spent of the toner are reduced. .

Further, when the particle size of the toner is reduced, the surface area per unit weight increases, and excessive charging due to rubbing is liable to occur. On the other hand, by adding titania having an aspect ratio of 2 to 12, titania having higher conductivity than the binder resin adheres to the surface of the base toner, and the specific surface area is higher than that of the spherical titania. Due to the large area, excessive charge rise of the toner is suppressed, and the image density is stable even with the lapse of time. In addition, under high temperature and high humidity, while maintaining the charge amount of the toner required for development, the toner particle surface The charge uniformity of the toner, the charge exchange between toner particles is accelerated, the charge speed is improved, and the charge distribution can be sharpened. As a result, the dependence of the charge on the toner environment is greatly improved. Can be suppressed.

Here, the aspect ratio is a ratio of the diameter of the long axis to the short axis, and the diameter of the long axis and the short axis are measured by a transmission electron microscope. Here, each of the 100 particles is measured. The average of the ratio between the major axis and the minor axis of the particles was defined as the aspect ratio.

The toner for electrophotography of the present invention is characterized in that the liberation of titania is 0.5 to 8%, and particularly preferably, the liberation of titania is 0.5 to 5%.

If the release rate of titania is higher than 8%, the released titania adheres to the photoreceptor, the developing roller and the carrier, and causes a development trouble such as filming of the photoreceptor and the developing roller and defective cleaning. Cheap.

Further, the liberated titania easily contaminates the carrier surface and lowers the charge imparting ability of the carrier itself, so that it is liable to cause background fouling due to poor charging of the developer and a decrease in developability.

On the other hand, if the release ratio of titania is lower than 0.5%, the additive hardly adheres to the base toner and is embedded in the surface of the base toner, so that sufficient fluidity cannot be obtained.

Conversely, if the release rate of titania is in the range of 0.5 to 5%, filming of the photoreceptor and the developing roller and adhesion to the carrier do not occur. Obtainable.

The titania release rate was measured by the following equation using PT1000 manufactured by Yokogawa Electric Corporation.

Release rate of titania

(Equation 1) T ¹ : count number of Ti element which did not emit light simultaneously with C element T ² : count number of Ti element which emitted light simultaneously with C element

The measurement conditions at this time are shown below. Analysis wavelength: Ti element: 334.900 nm C element: 247.860 nm Spectroscope used: Ti element: No. 1 or No. 2 (blaze wavelength: 2
50 nm) C element: No. 3 or No. 4 (blaze wavelength: 40
0 nm) Measurement gas: O ₂ 0.1% He gas Number of C elements detected in one scan: 500 to 1500 Noise cut level: 1.5 or less Sort time: 20 digits

Here, the main component of the C element is a parent toner, and even when titania surface-treated with a silane coupling agent or the like is used as an additive, the substantial addition amount is at most several parts by weight. Since the amount of C element detected by the silane coupling agent is almost insignificant compared to that of the base toner, the liberation rate of titania used as an additive can be obtained from the above equation.

Here, the added amount of titania is preferably 0.1 to 2.5 parts by weight with respect to the base toner.
Particularly preferably, it is 0.2 to 2.0 parts by weight.

If the addition amount is less than 0.1 parts by weight, the fluidity of the toner is reduced, so that sufficient chargeability cannot be obtained, which tends to cause background stain and toner scattering.

Further, when a solid image is output, transfer unevenness and white spots are likely to occur on the image, making it difficult to obtain a uniform solid image.

When the amount is more than 2.5 parts by weight, although the fluidity is improved, poor cleaning of the photoreceptor such as chattering and turning up of the blade and filming on the photoreceptor due to additives released from the toner are liable to occur. As a result, the durability of the cleaning blade and the photoconductor decreases. Furthermore, toner dust tends to occur in a thin line portion called a transfer dust, and this tendency becomes more remarkable particularly when two or more colors of toner are developed in a superposed manner as in a color thin line.

Further, when used as a color toner, if a large amount of titania is contained, when a toner image formed on a transparent sheet is projected by an overhead projector, the projected image is blurred, and a clear projected image is formed. It is difficult to obtain.

Here, there are various methods for measuring the amount of titania to be added, but it is generally determined by X-ray fluorescence analysis. That is, a calibration curve was prepared by a fluorescent X-ray analysis method for a toner with a known addition amount of titania, and the addition amount of titania was determined using this calibration curve.

The average primary particle size of the titania used in the present invention is 0.002 to 0.1 from the viewpoint of imparting fluidity.
μm, preferably 0.005 to 0.05 μm.

When the average primary particle diameter is smaller than 0.002 μm, the additives are easily embedded in the surface of the base toner, and the durability tends to be reduced. This tendency is more remarkable when used for a color toner having a sharp melt property. On the other hand, if it is smaller than 0.002 μm, aggregation of titania tends to occur easily, and it becomes difficult to obtain the desired fluidity.

When the average primary particle diameter is larger than 0.1 μm, the fluidity of the toner is reduced, so that a sufficient chargeability cannot be obtained, which is liable to cause background contamination and toner scattering.
Here, the particle size of titania was measured with a transmission electron microscope.

Further, the titania used in the present invention is:
It is preferable that the surface is treated with a hydrophobizing agent or the like. This surface treatment makes it possible to impart sufficient fluidity to the toner. Here, typical examples of the hydrophobizing agent include the following.

Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, chloromethyldimethyl Chlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinylmethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxy Propyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyltri Lorosilane, decyltrichlorosilane, nonyltrichlorosilane, (4-t-propylphenyl) trichlorosilane, (4-t-butylphenyl) trichlorosilane, dibentyldichlorosilane, dihexyldichlorosilane, dioctyldichlorosilane, dinonyldichlorosilane, Didecyldichlorosilane, didodecyldichlorosilane, dihexadecyldichlorosilane, (4-
(t-butylphenyl) octyldichlorosilane, dioctyldichlorosilane, didecenyldichlorosilane, dinonenyldichlorosilane, di-2-ethylhexyldichlorosilane, di-3,3-dimethylbentyldichlorosilane, trihexylchlorosilane, trioctylchlorosilane , Tridecylchlorosilane, dioctylmethylchlorosilane, octyldimethylchlorosilane, (4-t-propylphenyl) diethylchlorosilane, isobutyltrimethoxysilane, methyltrimethoxysilane, octyltrimethoxysilane, trimethoxy (3,3,3-trifluoropropyl ) Silane, hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane, hexatolyldisilazane and the like.

In addition, titanate-based coupling agents and aluminum-based coupling agents can also be used.

The electrophotographic toner of the present invention further includes
Contains other additives in addition to the above-mentioned titanium oxide
You can also. Such additives include, for example, S
iO _Two, Al_TwoO_Three, MgO, CuO, ZnO, SnO_Two,
CeO_Two, Fe_TwoO_Three, BaO, CaO, K_TwoO (Ti
O_Two), Al_TwoO_Three・ 2SiO_Two, CaCO_Three, MgCO_Three,
BaSO4, MgSO_Four, MoS_Two, Silicon carbide, nitride
Such as boron, carbon black, graphite, and fluorinated graphite
Which inorganic fine powder, polystyrene, polycarbonate, poly
Limethyl methacrylate, polyvinylidene fluoride, etc.
Polymer fine powder and the like;
More than seeds can be used as they are or after surface treatment
Wear.

[0043] In addition, the electrophotographic toner of the present invention, D _V / D _n is 1.3, which is the ratio of the weight-average diameter D _V and the number average diameter D _n
Preferably less, particularly preferably, D _V / D _n
Is 1.25 or less.

When D _V / D _n exceeds 1.3, the toner having a large particle diameter, which is excellent in developability, is selectively developed, and the toner having a small particle diameter tends to stay in the developing machine for a long time. , The developability gradually decreases, and the durability also deteriorates.

In addition, since the toner having such a small particle diameter has strong cohesiveness and low fluidity, uneven transfer and white spots particularly in a solid image, and missing during transfer in a thin line portion are liable to occur. It is likely to cause background contamination, toner scattering and filming on the photoconductor. Further, these toners having strong cohesiveness tend to have insufficient contact charge with the carrier, and have a low charge rising property, which further causes background contamination and toner scattering.

Further, when D _V / D _n exceeds 1.3 in the copying of the solid portion, the toner having the large particle size and the small particle size toner around the large particle size toner are added to the developed solid portion. However, the toner having a small particle diameter existing around the toner having a large particle diameter is difficult to be transferred, which is not preferable because it causes transfer unevenness and white spots.

Further, in the color toner, particularly in the halftone portion, the glossiness is high in the portion where the large particle size toner is fixed, and the glossiness is low in the portion where the small particle size toner is fixed, and the color toner is developed. Since the gloss of the image varies depending on the particle size of the toner, it causes a reduction in image quality due to uneven gloss.

As the binder resin used in the toner of the present invention, all known resins can be used. For example, polystyrene, poly-p-styrene, a homopolymer of styrene such as polyvinyltoluene and a substituted product thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene -Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic Acid butyl copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer,
Styrene-maleic acid ester copolymer, styrene-based copolymer such as polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, Rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin and the like can be used alone or in combination.

As the colorant used in the toner of the present invention, known dyes and pigments can be used. Examples of yellow colorants include naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, loess, graphite, titanium yellow, polyazo yellow, oil yellow, Hansa yellow, (GR, A,
RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Benzimidazolone Yellow, Isoindolinone yellow and the like.

Examples of the red colorant include red iron red, red lead, red lead, cadmium red, cadmium mercury red, antimony red, permanent red 4
R, para red, fire red, para chloro ortho nitroaniline red, lysole fast scarlet G, brilliant fast scarlet, brilliant carmine BS, permanent red (F2R, F4R,
FRL, FRLL, F4RH), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lisor Rubin GX, Permanent Red (F5R, FBB), Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Museum, Eosin Lake, Rhodamine Lake B,
Rhodamine lake Y, alizarin lake, thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, polyazo red,
Chrome vermilion, benzidine orange, perinone orange, oil orange and the like.

Examples of the blue colorant include, for example, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, and indanthrene blue (RS, B
C), indigo, ultramarine, navy blue, anthraquinone blue,
Fast Violet B, Methyl Violet Lake,
Cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green And the like.

Examples of the black colorant include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black and aniline black, metal salt azo dyes, metal oxides and composite metal oxides. Can be Further, the black toner may be a combination of a yellow colorant, a red colorant, and a blue colorant, or may be arbitrarily combined with another colorant with a black colorant such as carbon black.

Other coloring agents include titanium oxide, zinc white, lithopone, nigrosine dye, iron black and the like. The content of these coloring agents is usually in the range of 1 to 30% by weight based on the binder resin.

In the toner of the present invention, it is preferable to use a charge control agent mixed (internally added) with toner particles or mixed (externally added) with toner particles. The charge control agent makes it possible to control the amount of charge optimally according to the developing system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the amount of charge.

To control the toner to be positively charged,
Nigrosine and its modifications, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate,
Quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide, diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate, alone or 2
More than one kind can be used in combination.

In order to control the toner to be negatively charged, a salicylic acid metal complex or salt, an organic boron salt, a calixarene-based compound, or the like is used.

Further, in the toner of the present invention, a releasing agent can be contained in order to improve the releasability of the toner from the fixing member at the time of fixing and to improve the fixing property of the toner. .

As the release agent in this case, any known material can be used, but an ester-based or olefin-based wax is particularly preferred as the release agent. Since these release agents are more uniformly dispersed in the binder resin,
It shows excellent offset resistance, and is particularly effective when a polyester resin is used as the binder resin.

Here, the ester wax refers to a wax having an ester bond, and includes natural waxes such as candelilla wax, carnauba wax and rice wax, and the olefin wax includes polyethylene wax. Wax, polypropylene wax, Fischer-Tropsch wax and the like. The content of these release agents is usually 1 to 20% by weight, preferably 2 to 10% by weight, based on the binder resin.

Further, the toner of the present invention contains a magnetic material and can be used as a magnetic toner. Specific magnetic materials include iron oxides such as magnetite, hematite, and ferrite; metals such as cobalt and nickel; and metals and aluminum, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, and calcium. , Manganese, selenium, titanium, tungsten, alloys with metals such as vanadium and mixtures thereof.

These magnetic materials have an average particle size of 0.1 to 2 μm.
and about 200 to 200 parts by weight, particularly preferably 40 to 100 parts by weight of the binder resin.
１５０150 parts by weight.

The toner of the present invention is generally manufactured as follows. (1) The above-mentioned binder resin, pigment or dye as a colorant, or, if necessary, a charge control agent, a lubricant, other additives, and the like are sufficiently mixed by a mixer such as a Henschel mixer. (2) Batch type two rolls, Banbury mixer or continuous twin screw extruder, for example, KTK type 2 manufactured by Kobe Steel Ltd.
Screw extruder, TEM twin screw extruder manufactured by Toshiba Machine Co., Ltd., KC
The twin-screw extruder manufactured by K Company, the PCM twin-screw extruder manufactured by Ikegai Iron Works, the KEX twin-screw extruder manufactured by Kurimoto Iron Works, and the continuous single-screw kneader, such as the co-kneader manufactured by Buss Co. The constituent materials are well kneaded using a kneader. (3) After cooling the kneaded material, coarsely pulverize using a hammer mill or the like, further pulverize using a fine pulverizer using a jet stream or a mechanical pulverizer, using a classifier using a swirling stream or a Coanda effect. The particles are classified to a predetermined particle size by a classifier to obtain a base toner.

The toner of the present invention can be produced by a polymerization method, a capsule method, or the like as other production methods. The outline of these production methods is described below.

(Polymerized toner) (1) A polymerizable monomer, and if necessary, a polymerization initiator, a colorant, and the like are granulated in an aqueous dispersion medium. (2) Classify the granulated monomer composition particles to an appropriate particle size. (3) Polymerize the monomer composition particles having a specified internal particle diameter obtained by the above classification. (4) After performing a suitable treatment to remove the dispersant, the polymerization product obtained above is filtered, washed with water, and dried to obtain a base toner.

(Capsule Toner) (1) A resin, magnetic powder and the like, if necessary, are kneaded with a kneader or the like to obtain a molten toner core material. (2) The toner core is placed in water and vigorously stirred to produce a fine particle core. (3) The core material fine particles are put into a shell material solution, and a poor solvent is dropped with stirring, and the core material is encapsulated by covering the surface of the core material with the shell material. (4) The capsule obtained above is filtered and dried to obtain a base toner.

Then, the base toner and additives such as inorganic oxides are sufficiently mixed by a mixer such as a Henschel mixer (manufactured by Mitsui Miike), a mechanofusion system (manufactured by Hosokawa Micron), a mechanomill (manufactured by Okada Seiko). And, if necessary, pass through a sieve having an opening of about 150 μm or less,
Aggregates and coarse particles are removed.

Here, the toner for electrophotography of the present invention has a stirring blade peripheral speed of 15 when mixing the base toner and the additive.
~ 35 m / sec. , And the mixing time of the base toner and the additive is at least 50 sec. It is preferable that it is above.

When the peripheral speed of the stirring blade is 15 m / sec. If lower, or the mixing time of the base toner and the additive is 50 seconds.
c. If shorter, insufficient mixing will take place.
The additives are not uniformly mixed, and the released additives adhere to the photoreceptor, the developing roller and the carrier, and are likely to cause development troubles such as filming of the photoreceptor and the developing roller. It becomes easy to cause background soiling and deterioration of developability due to defects.

Conversely, when the stirring blade peripheral speed is 35 m / sec. If the value is higher, the additive strongly adheres to the base toner and is easily embedded in the surface of the base toner, so that sufficient fluidity cannot be obtained. In addition, the toner may melt due to heat generated during mixing, and in particular, in the case of a color toner,
Since a softening binder resin having a large amount of low molecular weight components is generally used, the tendency is more remarkable.

The toner for electrophotography according to the present invention is applicable to both one-component toner and two-component toner. When used as a two-component toner, it is used as a mixture with a carrier.

As the carrier that can be used in the present invention, all known carriers such as magnetic powders such as iron powder, ferrite powder and nickel powder, glass beads and the like can be used. Is preferably coated with a resin or the like.

In this case, the resin used is, for example, polyfluorocarbon, polyvinyl chloride, polyvinylidene chloride, phenol resin, polyvinyl acetal, acrylic resin, silicone resin and the like.

As a method of forming the resin layer, a resin may be applied to the surface of the carrier by a spraying method, a dipping method, or the like, as in the related art.

The carrier has an average particle size of usually 10 to 100 μm, preferably 30 to 60 μm.
The amount of the resin used is usually 1 to 10% by weight based on 100 parts by weight of the carrier.

Further, the mixing ratio of the toner and the carrier is generally 0.5 to 0.5 parts per 100 parts by weight of the carrier.
About 7.0 parts by weight is appropriate.

Next, an embodiment of the image forming method according to the present invention will be described. Here, FIG. 1 is an explanatory diagram showing an example of the image forming method according to the present invention. In FIG. 1, reference numeral 1 denotes a photosensitive drum serving as an image bearing member. When the photosensitive drum 1 is driven to rotate in the direction of the arrow, it is not shown in a portion uniformly charged by the charging device 2. Image exposure indicated by an arrow 3 is performed by the exposure unit, and an electrostatic latent image is formed on the photosensitive drum 1. The latent image forming portion reaches the position facing the developing device 5 via the eraser 4 and the electrostatic latent image is visualized as a toner image. On the other hand, the transfer material is conveyed from a paper supply unit (not shown) to an image forming unit via a registration roller 7, and a toner image on the photosensitive drum 1 is transferred by a transfer device 6 having a transfer belt 6a. The transfer material after the transfer is sent to a fixing device (not shown) by the transfer belt 6a, and the toner image is fixed on the transfer material.

After the transfer, the toner remains on the photosensitive drum 1, and the remaining toner is cleaned by the cleaning device 8. Then, the photosensitive drum 1 after cleaning is cleaned of residual charges by the charge removing device 9 to be ready for the next image formation.

[0078]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these. The parts in the examples represent parts by weight.

Production Example 1 of Base Toner Binder resin Polyester resin 70 parts Styrene-acrylic resin 30 parts Colorant carbon black 10 parts Charge control agent Fe-containing azo dye 2 parts Release agent Carnauba wax 5 parts

The above-mentioned materials were mixed by a Henschel mixer, and then melt-kneaded by a biaxial kneader heated to 140 ° C. The kneaded material is cooled with water, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then, using an air classifier, the following weight average diameter D _V , number average diameter D _n , and D _V
/ D _n was obtained. Weight average diameter D _V number average diameter _{D n D V / D n 7.2μm} 5.3μm 1.36

Preparation Example 2 of Base Toner The same materials as in Preparation Example 1 were mixed with a Henschel mixer and then melt-kneaded with a biaxial kneader heated to 140 ° C. After water-cooling the kneaded material, coarsely pulverized with a cutter mill,
After pulverizing with a fine pulverizer using a jet stream, a parent toner having the following weight average diameter D _V , number average diameter D _n , and D _V / D _n was obtained using an air classifier. Weight average diameter D _V number average diameter _{D n D V / D n 7.0μm} 5.7μm 1.23

Here, the particle size distribution of the toner can be measured by various methods. In the present invention, the measurement was performed using a Coulter Multisizer. That is, an interface that outputs a number distribution and a volume distribution using a Coulter Multisizer IIe type (manufactured by Coulter) as a measuring device.
(Manufactured by Nikkaki) and a personal computer were connected, and a 1% aqueous NaCl solution was prepared using primary grade sodium chloride as an electrolyte.

The measuring method is as follows.
In 150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant,
Further, 2 to 20 mg of a measurement sample is added, and about 1
Dispersion processing was performed for ~ 3 minutes.

Further, in another beaker, the electrolytic aqueous solution 100 was added.
２００200 ml, the sample dispersion was added to the mixture to a predetermined concentration, and the average of 50,000 particles was measured using the Coulter Multisizer IIe with a 100 μm aperture as an aperture. Was.

Example 1 Base Toner Production Example 1 100 parts Additive Titania (aspect ratio: 3.5, average primary particle size: 0.015 μm) 1.2 parts was stirred by a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain the electrophotographic toner of Example 1.

Example 2 Base Toner Production Example 1 100 parts Additive Titania (aspect ratio: 7.4, average primary particle size: 0.015 μm) 1.2 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain an electrophotographic toner of Example 2.

Example 3 Base Toner Production Example 1 100 parts Additive Titania (aspect ratio: 2.7, average primary particle size: 0.015 μm) 0.7 part was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain an electrophotographic toner of Example 3.

Example 4 Base toner Production Example 2 100 parts Additive Titania (aspect ratio: 4.7, average primary particle size: 0.015 μm) 1.2 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain an electrophotographic toner of Example 4.

Comparative Example 1 Base Toner Production Example 1 100 parts Additive Titania (aspect ratio: 1.5, average primary particle size: 0.015 μm) 1.2 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain an electrophotographic toner of Comparative Example 1.

Comparative Example 2 Base Toner Production Example 1 100 parts Additive Titania (aspect ratio: 13.0, average primary particle size: 0.015 μm) 1.2 parts by a Henschel mixer, stirring blade peripheral speed was 25 m /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having a mesh size of 150 μm to obtain an electrophotographic toner of Comparative Example 2.

Comparative Example 3 Base toner Production Example 1 100 parts Additive Titania (aspect ratio: 3.5, average primary particle diameter: 0.015 μm) 2.7 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having an opening of 150 μm to obtain an electrophotographic toner of Comparative Example 3.

Comparative Example 4 Base toner Production Example 1 100 parts Additive Titania (aspect ratio: 7.4, average primary particle size: 0.015 μm) 1.2 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 25 m. /
sec. Is set to be mixed for 20 seconds, and then air sieved with a sieve having an aperture of 150 μm.
An electrophotographic toner of Comparative Example 4 was obtained.

Comparative Example 5 Base toner Production Example 1 100 parts Additive Titania (aspect ratio: 7.1, average primary particle diameter: 0.015 μm) 1.2 parts was stirred with a Henschel mixer at a stirring blade peripheral speed of 10 m. /
sec. And then mix for 100 seconds,
Thereafter, air sieving was further performed with a sieve having a mesh size of 150 μm to obtain a toner for electrophotography of Comparative Example 5. The release rate of titania was measured for the electrophotographic toners of these examples and comparative examples. Table 1 shows the results.

Manufacture of carrier Core material 100 parts of Cu-Zn ferrite (average particle diameter 45 μm) Coating material Silicone resin (SR-2411, solid content 20% by weight, manufactured by Dow Corning Toray Silicone Co., Ltd.) 2 parts 100 parts of core material On the other hand, 1.2 parts of the coating material was coated using a fluidized bed, and baked at 210 ° C. for 2 hours to obtain a carrier coated with the above resin.

Production of Developer Examples 1 to 4 and Comparative Examples 1 to
5 parts of each of the toners obtained in 5 and 95 parts of the above carrier were mixed with a Turbula mixer to obtain an electrophotographic developer.
Further, the toner for electrophotography and the developer for electrophotography of these Examples and Comparative Examples were prepared by using commercially available copying machines (imageMioM).
F6550, manufactured by Ricoh Co., Ltd.), and 50,000 sheets were continuously copied under normal temperature / humidity environment, and the following various evaluations were made. Table 1 shows the results.
Here, ◎, ◎, Δ, and × in Table 1 are obtained by evaluating each of the evaluation items on a four-point scale. , X indicate levels having practical problems.

Evaluation 1: Image Density The image density was evaluated by measuring the image of the solid portion with a Macbeth densitometer RD918 at the initial stage and after continuous copying of 50,000 sheets, and evaluating the difference from the image density of the same portion in the initial image. did. Here, it is shown that the lower the image density, the lower the durability. Table 1 shows the results.

Evaluation 2: Background dirt The background dirt was evaluated at the initial stage and after continuous copying of 50,000 sheets.
The degree of occurrence of background contamination in the non-image area was visually evaluated in four stages. Table 1 shows the results.

Evaluation 3: Toner Scattering Toner scattering was evaluated in four stages visually at the initial stage and after continuous copying of 50,000 sheets. Table 1 shows the results.

Evaluation 4: Filming Filming was evaluated after continuous copying of 50,000 sheets.
The degree of filming of the photoreceptor was visually evaluated in four stages. Table 1 shows the results.

[0100]

[Table 1]

[0101]

As described above, according to the present invention, a toner for electrophotography which is excellent in developability and durability, which are the problems of a toner having a small particle diameter, and has little occurrence of background stain and filming, and the production thereof. A method and an image forming method are provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming method according to an embodiment of the present invention.

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Yoichiro Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masahide Yamashita 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Kazuto Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Keiko Shiraishi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company F-term (reference) 2H005 AA08 AB10 CB07 EA05 EA10

Claims (6)

[Claims] 1. A least a binder resin, the weight comprising an additive added to the toner base consisting of colorants average diameter D _V of 4.0
In an electrophotographic toner having a particle size of about 9.0 μm, titania having an aspect ratio of at least 2 to 12 is used as an additive.
% For electrophotography. 2. The electrophotographic toner according to claim 1, wherein the titania has an aspect ratio of 5 to 10. 3. The electrophotographic toner according to claim 1, wherein the release rate of titania is 0.5 to 5%. Wherein the ratio of the weight-average diameter D _V and the number average diameter D _n is D
The electrophotographic toner according to claim 1, wherein _V / D _n ≦ 1.3. 5. A stirring blade having a peripheral speed of 15 to 35 m / sec when mixing a base toner and an additive. And the mixing time of the base toner and the additive is at least 50 sec.
The method for producing an electrophotographic toner according to claim 1, wherein: 6. A developing means for applying a toner to an electrostatic latent image formed on an image carrier to form a visible image, and applying a toner image formed by development of the developing means to a transfer material electrostatically. In an image forming method having at least transfer means for transferring to
An image forming method using the toner for electrophotography according to claim 1.