JP4028114B2 - Developer and image forming apparatus - Google Patents

Description

【００８７】
【表２】

【００８８】
【発明の効果】
本発明によれば、ルチル／アナターゼ混晶型酸化チタンを外添することにより、優れた帯電安定性、流動性、及び耐久安定性を有する現像剤が得られる。
【００８９】
また、本発明の現像剤に、さらに疎水性シリカと併用することにより、流動性及び帯電性がより良好となる。
【図面の簡単な説明】
【図１】 本発明に用いられるルチル／アナターゼ混晶型酸化チタンのＸ線回折測定結果を表すグラフ図
【図２】 ルチル型酸化チタンのＸ線回折測定結果を表すグラフ図
【図３】 アナターゼ型酸化チタンのＸ線回折測定結果を表すグラフ図
【図４】 本発明の現像剤を適用し得る現像装置の一例を表す該略図
【符号の説明】
１…感光体
２…現像剤容器
３…現像剤
４…多極マグネルットロール
５…現像スリーブ
６…規制ブレード
７…電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developer for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and more particularly to a developer for full-color recording.
[0002]
[Prior art]
In an electrophotographic apparatus or an electrostatic recording apparatus, a toner and a carrier are conventionally used to visualize an electrostatic latent image formed on an electrostatic image holding body from a photosensitive member or a dielectric. A component-based development method and a one-component development method using a toner having a carrier function are widely used.
[0003]
In general, a toner used in such an electrophotographic development method is obtained by melt-mixing a colorant and other additives in a thermoplastic resin and uniformly dispersing the mixture, and then finely pulverizing and classifying the solidified product. Manufactured as colored fine particles.
[0004]
In electrophotographic apparatuses or electrostatic recording apparatuses, development from mono-color to full-color recording has progressed. In general, all three color toners, yellow, cyan, and magenta, are used to reproduce all colors. Came to do.
[0005]
In this method, an electrostatic latent image is formed by irradiating light from an original on a photoconductor through a color separation filter having a complementary color relationship with the color of the toner, and then developing and transferring the toner. Hold on a support. This process is sequentially performed a plurality of times for each color, and the final full-color image is obtained by one-time fixing after superimposing the toner on the same support while aligning the registration.
[0006]
In the case of a developing method using a so-called two-component developer in which a developer is composed of a toner and a carrier, the toner is charged to a required charge amount and charge polarity by friction with the carrier, and electrostatic attraction is used. The electrostatic image is developed with toner. The toner needs to have good frictional charging characteristics determined mainly by the relationship with the carrier.
[0007]
As means for imparting charging stability, fluidity, durability stability and the like to the toner, proposals have been made to add fine particles called external additives to the surface of the toner particles.
[0008]
For example, it has been proposed to add a charge control agent such as chargeable fine particles to the toner, use resin fine powder having a polarity opposite to that of the toner, or add a fluorine-containing compound to the developer.
[0009]
For example, titanium oxide is used as an abrasive and a fluidizing agent, or has been surface-treated with titanium oxide fine particles to impart positive chargeability to the toner. Further, it is used in combination with hydrophobic silica to suppress the charge amount of silica. In addition, it has been proposed to use anatase-type titanium oxide, titanium oxide treated with alkyltrialkoxysilane, amorphous hydrophobic titanium oxide, rutile-type titanium oxide, or the like as a charge control agent.
[0010]
However, even if any external additive is added, satisfactory charging stability, fluidity, durability stability and the like are not obtained.
[0011]
Further, since the color toner does not contain a conductive substance such as magnetic powder or carbon black like black toner, it is difficult to leak frictional charges, and the charge amount of the toner tends to increase without stabilization.
[0012]
Also, full-color toners are 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.
[0013]
In order to improve such chargeability, all materials constituting the toner and developer, such as a charge control agent added to the toner, a fluidity imparting agent, a binder resin, and further, a core agent and a coating agent of the carrier, etc. In order to achieve excellent triboelectric charging properties, studies have been made.
[0014]
In the case of a color toner, it is known that metal oxide fine particles such as titanium oxide that do not affect the hue of the toner are externally added to the toner surface. However, satisfactory chargeability was not obtained.
[0015]
For example, rutile-type titanium oxide has a small surface activity and has not been sufficiently hydrophobized. In addition, it was possible to increase the degree of hydrophobicity by using a large amount of treatment agent or using a high-viscosity treatment agent. It was inferior in fluidity because it could not be sufficiently hydrophobized, such as being non-uniform. Further, when used together with silica to supplement fluidity, there is a problem that the charging characteristics of the toner are impaired.
[0016]
Further, for example, Japanese Patent Application Laid-Open No. Hei 9 (1998) discloses a method in which the surface of rutile type titanium oxide is subjected to surface treatment with an inorganic oxide and then subjected to an organic treatment to make it hydrophobic so that particles are less likely to coalesce and can be treated uniformly and in one hour. Although it is disclosed in Japanese Patent Application Publication No. 7-244497, the degree of hydrophobicity is limited to 80%, and it is difficult to obtain a degree of hydrophobicity higher than that.
[0017]
Anatase-type titanium oxide has problems such as low volume resistivity, quick charge leakage under high humidity, and unstable charging.
[0018]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a developer having good charging stability, fluidity, and durability stability.
[0019]
[Means for solving the problems]
The present invention relates to a toner particle containing a colorant and a binder resin, a hydrolyzed rutile / anatase mixed crystal titanium oxide externally added on the toner particle, and a rutile titanium oxide. Or A developer containing a mixture with anatase-type titanium oxide is provided.
The present invention also provides an image carrier,
Toner particles provided on the image carrier and containing a colorant and a binder resin; as well as Hydrophobized rutile / anatase mixed crystal titanium oxide and rutile titanium oxide externally added on the toner particles Or A developer containing a developer containing a mixture with anatase-type titanium oxide, and developing the electrostatic latent image formed on the surface of the image carrier with the developer to form a developer image; Image forming apparatus I will provide a .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The developer of the present invention includes a toner in which a rutile / anatase mixed crystal type titanium oxide subjected to a hydrophobic treatment is externally added to toner particles containing a colorant and a binder resin.
[0021]
The rutile / anatase mixed type titanium oxide used in the present invention compensates for the disadvantages of both the rutile type titanium oxide and the anatase type titanium oxide, and is uniform and sufficient without causing coalescence between particles by a simple method. Can be hydrophobized and has a suitable volume resistivity. Such a hydrophobized rutile / anatase mixed crystal type titanium oxide is well dispersed in the developer, provides excellent fluidity, and provides excellent triboelectric charging properties with environmental stability. At the same time, a developer that is extremely durable against friction with a charge imparting member such as a carrier can be obtained.
[0022]
Furthermore, according to the present invention, an image having clear image characteristics can be obtained by using such a developer.
[0023]
Preferably, hydrophobic silica is further added to the developer of the present invention. By adding hydrophobic silica, fluidity and chargeability are improved. The rutile / anatase mixed crystal type titanium oxide used in the present invention does not cause problems such as impairing the charging characteristics of the developer even when used in combination with hydrophobic silica.
[0024]
The rutile / anatase mixed crystal type titanium oxide subjected to the hydrophobization treatment is preferably contained in the toner particles in an amount of 0.02 to 3.0% by weight.
[0025]
It is also possible to externally add rutile type and anatase type titanium oxide, which could not be used conventionally, into the developer together with the rutile / anatase mixed crystal type titanium oxide.
[0026]
When mixing a hydrolyzed rutile / anatase mixed type titanium oxide and a rutile or anatase type titanium oxide having a different degree of hydrophobization, the mixing ratio is 1: 8 to 1: 1. The toner particles are contained in an amount of 0.02 to 3.0% by weight, and the ratio of the rutile type to the anatase type in the mixture is preferably 5:95 to 90:10. Further, the degree of hydrophobicity of the rutile / anatase mixed crystal type titanium oxide is preferably larger than the degree of hydrophobicity of the rutile type or anatase type titanium oxide.
[0027]
The rutile / anatase mixed crystal titanium oxide used in the present invention can be preferably obtained by a dry method. For example, a volatile titanium compound such as titanium alkoxide is used as a raw material, vaporized or atomized, and then heated to 300 to 800 ° C. Titanium oxide can be obtained by decomposing at a temperature to form titanium oxide fine particles, and cooling in as short a time as possible to a temperature (preferably 100 ° C. or less) at which titanium fine particles are not reunited immediately after decomposition.
[0028]
Examples of the raw material for titanium oxide used in the present invention include titanium alkoxides such as titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetrabutoxide, and diethoxytitanium oxide, titanium tetrachloride, titanium tetrabromide, etc. Examples thereof include volatile titanium compounds such as titanium halides, trihalogenated monoalkoxytitanium, dihalogenated dialkoxytitanium, and monohalogenated trialkoxytitanium.
[0029]
After vaporizing or atomizing the volatile titanium compound, an oxygen-hydrogen containing gas is required to perform decomposition.
[0030]
As the hydrophobizing agent for titanium oxide used in the present invention, a coupling agent is preferable, and examples thereof include a silane coupling agent and a titanium coupling agent. Particularly preferably used is a silane coupling agent, which has the following general formula Rm-Si-Yn
R: Alcooxy group
m: an integer from 1 to 3
Y: hydrocarbon group including alkyl group, vinyl group, glycidoxy group, methacryl group n: an integer of 1 to 3
For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyl Examples include dimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.
[0031]
The amount of hydrophobic treatment is preferably 3 to 40% by weight with respect to 100% by weight of titanium oxide, and the degree of hydrophobicity is preferably 80 to 98%.
[0032]
If the degree of hydrophobicity is less than 80%, the decrease in charge amount due to standing for a long time under high humidity becomes large, and the treatment with the degree of hydrophobicity exceeding 98% is practically difficult. It can be done by using a large amount of treatment agent or using a highly viscous treatment agent, but it takes a long time for the hydrophobization treatment, and coalescence particles are produced at the hydrophobization stage. It becomes difficult to control the charging of the titanium oxide itself, and as a result, the developer is charged up under low humidity.
[0033]
The hydrophobization treatment is appropriately performed by, for example, immersing the titanium oxide fine particles in a solution containing a coupling agent and drying, or spraying a solution containing the coupling agent on the titanium oxide fine particles and drying. You can choose to do it.
[0034]
As another method of hydrophobizing, when titanium oxide is generated and rapidly cooled, the titanium oxide fine particles after thermal decomposition are treated with a hydrophobizing agent together with an inert gas refrigerant such as nitrogen gas to be hydrophobized. A method is also illustrated.
[0035]
Moreover, the preferable water content of the hydrolyzed rutile / anatase mixed crystal type titanium oxide used in the present invention is 1.0% or less, and the preferable BET specific surface area is 60 to 75 m. ² / G, a preferred particle size is 0.01 to 0.1 μm, a preferred bulk density is 75 to 110 g / l, and a preferred volume resistivity is 10 ⁸ -10 ¹¹ Ωcm.
[0036]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
[0037]
First, the manufacture example of the titanium oxide used for this invention is shown.
[0038]
Production example 1 of titanium oxide
The rutile-anatase mixed crystal type titanium oxide was obtained by a dry process, that is, a volatile titanium compound was hydrolyzed in a high-temperature gas phase, and the reaction product was rapidly cooled. Specifically, 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 ° C. is supplied to the burner and burned at a flame temperature of 300 to 800 ° C. for hydrolysis. The reaction product was immediately cooled at 100 ° C. for 30 seconds.
[0039]
As a result, crystalline titanium dioxide having an average primary particle diameter of 0.015 μm was obtained. The crystal form of the titanium dioxide was rutile type 10% and anatase type 90%.
[0040]
Next, 200 g of this titanium oxide powder is placed in a separable flask having an internal volume of 5 liters, and 20 g of hexyltrimethoxysilane is mixed well in a nitrogen gas atmosphere while mixing. Thus, titanium oxide A having a hydrophobicity of 90% was obtained.
[0041]
Various measurements and evaluations were performed on the obtained titanium oxide.
[0042]
The crystal form of titanium oxide was identified by X-ray diffraction. Apparently, peaks indicating anatase type (101) and rutile type (110) were observed in the same particle.
[0043]
In FIG. 1, the graph showing the X-ray-diffraction measurement result of the titanium oxide A is shown. As shown in the figure, the ratio of the anatase type (101) and the rutile type (110) was determined by the areas of the peaks 11 and 12, respectively, and was 90:10.
[0044]
The degree of hydrophobicity can be measured by the following method. 50 ml of water was put into a 200 ml beaker, and 0.2 g of silica or titanium oxide was further added. Then, while gently stirring with a magnetic stirrer, add methanol from the burette where the tip was immersed in water at the time of dropping, and the floating silica or titanium oxide began to sink, and the number of ml of methanol dropped when completely sinking was read. The following formula (1)
Hydrophobicity = (ml of methanol dropped) / (50 + ml of methanol dropped) × 100 (1)
It is requested from. In this case, methanol acts as a surfactant, and the silica or titanium oxide that floats as methanol is dropped is dispersed in water via methanol, so the higher the degree of hydrophobicity, the more hydrophobic the silica or titanium oxide. It can be said that the degree of conversion is high.
[0045]
The specific surface area means a BET specific surface area, and was measured here by a nitrogen adsorption method. For example, measurement was performed using a canter soap QS-16 type (manufactured by Kantachrome) using a flow-type nitrogen adsorption BET one-point method. That is, N ₂ Degas for 15 minutes at 200 ° C. under 100% gas flow, cool sample to liquid nitrogen temperature, He / N ₂ (N ₂ 30%) Flowing mixed gas, N ₂ N adsorbed at room temperature after adsorbing ₂ And desorbed N ₂ Was obtained by a thermal conductivity detector, and the total surface area calculated thereby was expressed as a ratio to 1 g of the dry mass of the sample.
[0046]
The water content means the Karl Fischer water content, and is measured by a constant voltage polarization voltage titration method using a Karl Fischer titrator. For example, it can be measured by a volumetric titration moisture measuring device KF-06 manufactured by Mitsubishi Chemical Corporation. That is, 10 μl of pure water is precisely weighed with a microsyringe, and the water content (mg) per ml of Karl Fischer reagent is calculated from the reagent titration necessary to remove this water. Next, 100 to 200 mg of a measurement sample is precisely weighed and sufficiently dispersed in a measurement flask with a magnetic stirrer for 5 minutes. After dispersion, measurement is started, and the titer (ml) of the Karl Fischer reagent required for titration is integrated to calculate the water content and water content according to the following formulas (1) and (13). Expressed quantity.
[0047]
Water content (mg) = reagent consumption (ml) × reagent titer (mgH ₂ O / ml) (2)
Moisture content (%) = (water content (mg)) / (sample amount (mg)) × 100 (3)
The bulk density means a light bulk density and a heavy bulk density, and was measured using a powder tester (manufactured by Hosokawa Micron). For the light bulk density, a sieve having an aperture of 710 μm is installed on a vibration table, and a measuring cup (capacity: 100 cc) whose weight has been measured in advance is placed immediately below the sieve. Next, an appropriate amount of sample was gently put on the sieve, the start button was pushed, the scale of the rheostat was gradually raised from 0, the shaking table was vibrated, and the sample was allowed to flow out into the measuring cup. When the heaped sample was filled in the cup, the vibration was stopped, and the upper surface of the heaped cup was ground with a blade and precisely weighed with a balance. The light bulk density was calculated by the following formula (4).
[0048]
Light bulk density (g / cm ² ) = (Sample mass (g)) / 100 (4)
Also, add a cap to the cup and gently place the sample up to the top of the cap. The powder tester was switched to tapping, the cup was placed on the tapping holder, the start button was pressed, and tapping was performed 180 times. If the sample fell below the top of the cup, the sample was added and continued. After tapping, the cap was gently removed from the cup, and the excess sample on the cup was ground with a blade and precisely weighed with a balance. The heavy bulk density is calculated by the same formula as the light bulk density. The particle diameter was observed with a transmission electron microscope, and the average particle diameter was determined by measuring the diameter of about 1000 particles in the field of view.
[0049]
The above measurement results are shown in Table 1-1 below.
[0050]
Production example 2 of titanium oxide
Rutile-type titanium oxide can be obtained by a wet method, that is, by purification through a chemical reaction or crystal growth in the liquid phase. Examples of the wet method include a sulfuric acid method and a hydrochloric acid method. Here, it manufactured by the hydrochloric acid method.
[0051]
First, after adding 40 wt% hydrochloric acid to titanium dioxide in a dispersion slurry of orthotitanic acid having a titanium dioxide concentration of 60 g / liter, the mixture was heated to the boiling point and maintained for 3 hours, and then filtered and washed.
[0052]
The obtained cake was dried at 110 ° C., calcined at 800 ° C. for 1 hour, and pulverized with an Ishikawa-type cracker to obtain crystalline titanium dioxide having an average primary particle size of 0.010 μm. A graph showing the result of X-ray diffraction analysis of the obtained titanium oxide B is shown in FIG. As shown in the figure, since the peak 13 appears only in the rutile type (110), it was found that the rutile type (110) was 100%.
[0053]
Next, in the same manner as in Production Example 1, titanium oxide B having a hydrophobicity of 50% was obtained.
[0054]
Moreover, about the obtained titanium oxide B, the same measurement and evaluation as the manufacture example 1 were performed. The results are shown in Table 1-1 below.
[0055]
Production example 3 of titanium oxide
Anatase-type titanium oxide is obtained by a wet method as in Production Example 2. Ammonia water is added to 100 g / liter of an aqueous titanium tetrachloride solution substantially free of sulfate ions at room temperature until the pH reaches 3.5, followed by heating to 80 ° C. and holding for 30 minutes to neutralize the precipitate. Got.
[0056]
Next, the precipitate was filtered and washed, and then the obtained cake was dispersed again in water to form a slurry, and ammonia water was added to adjust the pH to 7.0.
[0057]
It was then filtered, washed and dried at a temperature of 110 ° C. The mixture was formed at 800 ° C. for 1 hour and pulverized with an Ishikawa-type cracker to obtain crystalline titanium dioxide having an average primary particle size of 0.020 μm.
[0058]
A graph showing the result of X-ray diffraction analysis of the obtained titanium oxide B is shown in FIG. As shown, peak 14 is Anatase type (101) Appears only in the crystal form, Anatase type (101) Was found to be 100%.
[0059]
The crystal form of the titanium dioxide was anatase type 100%.
[0060]
Next, in the same manner as in Production Example 1, titanium oxide C having a hydrophobization degree of 60% was obtained.
[0061]
Further, the obtained titanium oxide C was subjected to the same measurement and evaluation as in Production Example 1. The results are shown in Table 1-1 below.
[0062]
As the binder resin used in the present invention, there can be used a copolymer of styrene and its substitute, and an acrylic resin, which are conventionally used as a binder resin for toner.
[0063]
Examples of the styrene and substituted copolymers thereof include polystyrene homopolymers, hydrogenated styrene resins, styrene-isobutylene copolymers, styrene-butadiene copolymers, acrylonitrile-butadiene-styrene terpolymers, Acrylonitrile-styrene-acrylic acid ester terpolymer, styrene-acrylonitrile copolymer, acrylonitrile-acrylic rubber-styrene terpolymer, acrylonitrile-chlorinated polystyrene-styrene terpolymer, acrylonitrile-EVA-styrene Ternary copolymer, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene rubber, styrene-maleic acid ester copolymer, styrene-isobutylene copolymer, styrene-maleic anhydride Such polymers may be mentioned.
[0064]
Examples of the acrylic resin include polyacrylate, polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, polyglycidyl methacrylate, polyfluorinated acrylate, styrene-methacrylate copolymer, and styrene-butyl methacrylate copolymer. And styrene-ethyl acrylate copolymer.
[0065]
In addition, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, phenol resin, urea resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic Aromatic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be used alone or in combination.
[0066]
Examples of the colorant used in the present invention include carbon black, organic or inorganic pigments and dyes. There are no special restrictions, but for carbon black, acetylene black, furnace black, thermal black, channel black, ketjen black, etc. Facial dyes include, for example, First Yellow G, Benzidine Yellow, Indian Fast Orange, Irgadine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Resol Red 2G, Raked C, Rhodamine FB, Rhodamine B Lake, Phthalocyanine Blue, pigment blue, brilliant green B, phthalocyanine green, quinacridone, etc. These may be used alone or in combination. As the mixing and dispersing means, a wet dispersion method using a high-speed dissolver, roll mill, ball mill or the like, a melt kneading method using a roll, a pressure kneader, an internal mixer, a screw type extruder, or the like can be used. As a means for coarse pulverization, for example, a hammer mill, a cutter mill, a jet mill, a roller mill, a ball mill, or the like can be used. Moreover, as a means for finely pulverizing the coarsely pulverized product, a jet mill, a high-speed rotary pulverizer, or the like can be used. As a means for classifying the finely pulverized product, an airflow classifier or the like can be used.
[0067]
In the present invention, if necessary, a wax for improving the anti-offset characteristic, a charge control agent for controlling the triboelectric charge amount, and the like can be blended. Examples of the charge control agent include negative polarity control agents such as alkyl salicylic acid metal chelates, chlorinated polyesters, acid group excess polyesters, chlorinated polyolefins, fatty acid metal salts, and fatty acid soaps.
[0068]
As the external additive, silica fine particles, metal oxide fine particles, cleaning aids and the like are used in addition to the titanium oxide of the present invention. Examples of the silica fine particles include silicon dioxide, aluminum silicate, sodium silicate, potassium silicate, zinc silicate, magnesium silicate and the like. Examples of the metal oxide fine particles include zinc 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 are preferably those subjected to surface treatment such as hydrophobization.
[0069]
As a means for mixing the external additive comprising the hydrophobic titanium oxide and the hydrophobic silica of the present invention, a known mixing apparatus can be used, but it is desirable to use, for example, a high-speed flow type mixing apparatus. Examples of the high-speed fluid mixing device include a Henschel mixer, a super mixer, and a micro speed mixer.
[0070]
The developer according to the present invention is produced, for example, as follows using a binder resin and a colorant.
[0071]
First, at least 100 parts by weight of the binder resin and 1 to 10 parts by weight of the colorant are mixed and dispersed 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 coarsely pulverized using a hammer mill, a jet mill or the like. Next, the mixture is finely pulverized using a jet mill or the like, and then classified to a desired particle size by an air classification method or the like, and then mixed with an external additive and a high-speed fluidized mixer to obtain the developer of the present invention. .
[0072]
The developer of the present invention thus obtained can be applied to all known development methods. For example, two-component development methods such as cascade method, magnetic brush method, microtoning method, conductive one-component development method, insulating one-component development method, one-component development method containing magnetic materials such as jumping development method, powder cloud And a non-magnetic one-component developing method in which the toner is electrostatically held on the developer carrying member and conveyed to the developing portion to be developed.
[0073]
The developer of the present invention can be applied to, for example, a copying machine having a two-component developing device having the configuration shown in FIG. In the following examples, using the copying machine shown in FIG. 4, an image was printed, and the change in the charge amount of the developer, the change in the toner density ratio (T / C), and the change in the image density (ID) were evaluated. .
[0074]
In FIG. 4, an electrostatic charge image is formed on the photosensitive drum 1. A toner container 2 in the vicinity of the photosensitive drum 1 contains toner and a carrier (developer) 3, and a multipolar magnet roll 4 and a developing sleeve 5 mounted on the outer periphery thereof are installed on the photosensitive drum 1 side. Has been. The carrier of the developer 3 adheres to the surface of the developing sleeve 5 by the magnetic force of the multipolar magnet roller 4, and toner particles adhere to the carrier surface to form a toner layer. In FIG. 4, the multipolar magnet roller is fixed, the developing sleeve is rotated counterclockwise, and the developer 3 is conveyed as needed. Further, the conveyance amount of the developer 3 is regulated by the regulation blade 6. At the same time, the photosensitive drum 1 is rotated clockwise, and a bias is applied from the power source 7 at a location where the developing sleeve 5 and the photosensitive drum 1 approach each other, and the electrostatic sleeve is applied to the photosensitive drum 1 from the developing sleeve 5 by electrostatic attraction. The toner 3 adheres to the electrostatic charge image and development is performed.
[0075]
Example 1 2 Comparative Examples 1 to 3
A toner was prepared with the following composition.
[0076]
100 parts by weight of polyester resin
5 parts by weight of phthalocyanine pigment
Metal dye 2 parts by weight
1 part by weight of low molecular weight polypropylene wax
The material of the above formulation was heated and melted and kneaded with an extruder, cooled, pulverized with a jet mill, and classified with an air classifier to obtain toner particles having a mean particle size of 8 μm and a particle size of 4 to 14 μm. To 100 parts by weight of the toner, 0.5 parts by weight of hydrophobic silica and 2.0 parts by weight of various titanium oxides shown in Tables 1-1 and 1-2 below are mixed by a high-speed mixer. F was obtained.
[0077]
Here, as the titanium oxide, a developer using the titanium oxide A of Production Example 1 is used. Reference example 1 The developer using the titanium oxide B of Production Example 2 is Comparative Example 1, the developer using the titanium oxide C of Production Example 3 is Comparative Example 2, and the developer using a mixture of titanium oxide A and titanium oxide B is used. Example 1 A developer using a mixture of titanium oxide A and titanium oxide C was used in Example 2, and a developer using a mixture of titanium oxide B and titanium oxide C was used as Comparative Example 3.
[0078]
Further, as the carrier, ferrite having a particle diameter of about 50 μm coated with a silicone resin was used as a carrier, and 8 parts by weight of each toner composition was added to 100 parts by weight of the carrier. Next, the mixture was mixed for 30 minutes with a V blender to obtain a developer.
[0079]
The results of the copy test are shown in Table 1-1 and Table 1-2 below. In the copy test, 5000 sheets were copied at low temperature and low humidity (10 ° C, 20% RH), 10,000 sheets at high temperature and high humidity (30 ° C, 80% RH), and 30000 copies at room temperature (20 ° C, 50% RH). Went.
[0080]
In addition, (circle) in each evaluation is favorable with no problem at all, and (triangle | delta) can be used somehow. X means that it cannot be used.
[0081]
The charge amount was measured with a blow-off powder charge amount measuring device TB-220 manufactured by Toshiba Chemical Corporation.
[0082]
The T / C concentration ratio was determined by measuring the weight when a certain amount of developer toner was removed by blowing with air.
[0083]
Image density was measured with a Macbeth densitometer.
[0084]
The fluidity was measured with a powder tester. Environmental characteristics were measured at low temperature and low humidity (10 ° C., 20% RH), high temperature and high humidity (30 ° C., 80% RH), and room temperature room humidity (20 ° C., 50% RH).
[0085]
Toner scattering was evaluated by observing the periphery of the developing device inside the copying apparatus.
[0086]
[Table 1]

[0087]
[Table 2]

[0088]
【The invention's effect】
According to the present invention, a developer having excellent charging stability, fluidity, and durability stability can be obtained by externally adding rutile / anatase mixed crystal type titanium oxide.
[0089]
Further, when the developer of the present invention is further used in combination with hydrophobic silica, fluidity and chargeability are further improved.
[Brief description of the drawings]
FIG. 1 is a graph showing the results of X-ray diffraction measurement of rutile / anatase mixed crystal titanium oxide used in the present invention.
FIG. 2 is a graph showing the results of X-ray diffraction measurement of rutile titanium oxide.
FIG. 3 is a graph showing the results of X-ray diffraction measurement of anatase-type titanium oxide.
FIG. 4 is a schematic diagram showing an example of a developing device to which the developer of the present invention can be applied.
[Explanation of symbols]
1 ... Photoconductor
2 ... Developer container
3 ... Developer
4 ... Multi-pole Magnelt roll
5. Development sleeve
6 ... Regulator blade
7 ... Power supply

Claims (3)

A mixture of toner particles containing a colorant and a binder resin, a hydrolyzed rutile / anatase mixed crystal type titanium oxide externally added on the toner particles, and a rutile type titanium oxide or anatase type titanium oxide. Contains developer.   The developer according to claim 1, wherein the ratio of the rutile type and the anatase type in the mixture is 5:95 to 90:10. An image carrier;
Toner particles provided on the image carrier and containing a colorant and a binder resin, and a hydrolyzed rutile / anatase mixed crystal type titanium oxide and a rutile type titanium oxide externally added on the toner particles Or a developer containing a developer containing a mixture with anatase-type titanium oxide, and forming a developer image by visualizing the electrostatic latent image formed on the surface of the image carrier with the developer. An image forming apparatus provided.

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