JPS62148970A - Insulating magnetic dry developer - Google Patents

Abstract

PURPOSE:To obtain a magnetic developer which obviates the fall of an image density, increases the image density, is hardly affected by an environmental change and can prevent the flow and disturbance of the image by incorporating a negative chargeable insulating toner contg. prescribed components, cerium particles having prescribed characteristics and pulverized silicon oxide particles subjected to a hydrophobing treatment into the developer. CONSTITUTION:The insulating magnetic dry developer which contains the negative chargeable insulating toner contg. at least a binder resin, magnetic material and zinc org. complex compd., the cerium oxide particles having 1.0-4.0mum volume mean grain size, <=0.5wt% heating loss up to 100 deg.C, and <=15m<2>/g BET specific surface area by a gaseous nitrogen adsorption method and essentially consisting of CeO2 and the negative chargeable pulverized silicon oxide particles subjected to the hydrophobing treatment is pred. The amt. of the zinc org. complex compd. to be added is 0.1-10wt% per the weight of the binder resin. The contents of the cerium oxide particles and the pulverized silicon oxide particles are respectively 0.1-5 and 0.01-3pts.wt. per 100pts.wt. magnetic toner particles.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an insulated outer magnetic tel dry developer for developing latent images in electronic IJ printing, static printing, static 7L printing, and the like. More specifically, in a developer for direct or indirect electrophotographic development, a toner that is uniformly strongly negatively charged, a negatively charged hydrophobic silica, and an insulating magnetic material containing at least specific cerium oxide particles is used. Regarding dry developer. Previously, regarding electrophotography, US Patent No. 2.297.
No. 691 Specification 1j-Equity (1?i 42-239104
Publication (U.S. Patent No. 3,666.363), Japanese Patent Publication No. 43-247448 (U.S. Patent No. 407136)
As described in No. 1 Specification) etc., the photoconductive layer I-
By performing one full charge and exposing a light image according to the original, the charge in the exposed area is extinguished and a 14% image is formed. Development is carried out by allowing a fine powder detection substance, so-called toner, to adhere to the static latent image. 1. toner is attracted to the electrostatic latent image depending on the amount of charge on the photoconductive layer, forming a toner image with shading. This toner image is transferred to a support surface such as paper or 41 as necessary, and then heated and pressed. It is permanently affixed to the supporting surface using a heated pressure roller or the like. Alternatively, if it is desired to omit the toner image transfer step, the toner image can be fixed to the photoconductor layer. In addition to the fixing methods described above, other means such as solvent treatment or coating treatment can also be used. There are many known developing methods for electrophotography, including a developing method that uses carrier particles and toner as a two-component developer, such as the gascade developing method described in U.S. Pat. No. 2,618,552, and U.S. Pat. No. 2,874,06
The magnetic brush method described in the specification of No. 3 has been widely used. All of these methods are excellent methods in which good images can be obtained relatively stably, but on the other hand, they have common problems associated with two-component developers, such as deterioration of the carrier and fluctuations in the mixing ratio of toner and carrier. In order to avoid such problems, various development methods have been proposed that use a one-component developer containing less carrier than toner. Among them, magnetic +
As an example of a method using a developer consisting of a single particle of I, for example, US Pat. I have a suggestion. This is a cylindrical n-conductor toner 11 holder (sleeve) with magnetism 41 inside.
11 supports a magnetic developer and brings it into contact with an electrostatic image to develop it. At this time, a conductive path is formed between the recording medium surface and the sleeve surface by the i-toner particles in the developing device, and charges are led from the sleeve to the toner particles through this conductive path, and between the electrostatic image and the image area. The toner particles 1f are developed in the image area by the Coulomb force. This developing method using conductive magnetic toner is an excellent method that avoids the problems associated with conventional one-component developing methods.
On the other hand, since the toner is conductive, there is a problem in that it is difficult to electrostatically transfer the developed image from the recording medium to the final support member such as plain paper. For this reason, methods for developing electrostatically transferable magnetic toners having high electrical resistance or electrical insulation of 100 cm or more have been proposed. For example, US Pat. No. 4,336,318 proposes a developing method using magnetic toner having electrical insulation properties. Also, British patent 1,503
．． No. 560 proposes a method of developing an electrostatic latent image with toner in which the magnetic material is exposed. In a developing method using an insulating magnetic developer that does not contain carrier particles, a tripoelectric charge is attached to the toner particles by friction between the toner particles and a toner carrier (i.e., a developing sleeve) and/or friction between toner particles. , I'm looking forward to it. When a two-component developer containing a carrier is used, it is possible for the toner particles to obtain a large amount of tripocharge due to the frequent frictional contact with the carrier, which is much larger in quantity, and the stirring action of the carrier. Since it is difficult to obtain triplicate charges in two-component developers, a charge control agent is usually contained in the toner particles. In addition, unlike the -component developers, these -component developers do not have carrier particles that also play the role of picking up the toner, so they tend to aggregate in the developing device. It is added as an external additive. In the case of a fluidizing agent or silicon oxide fine particles, since the silicon oxide fine particles themselves have negative charge properties, they can serve as a good auxiliary agent for holding negative charges for negatively charged toners. However, since toner has a negative market and silicon oxide fine particles also have the same negative charge, an electrostatic repulsive force acts, and it is difficult for silicon oxide particles to attach well to i-toner. As a result, low image density and a remarkable 1'/difference phenomenon of image density occurred especially in the early stages of operation of the machine. The object of the present invention is to provide an insulating magnetic developer that eliminates the image flicker phenomenon that occurs with conventional ~ component developers containing negatively charged insulating magnetic toners. A further object of the present invention is to provide an insulating magnetic +1 developer that forms and rjs multiple q images with high image density. It is an object of the present invention to provide an insulating magnetic developer that is not easily affected by the effects of the film.A further object of the present invention is to prevent the formation of a coating on the surface of an image carrier, which is the cause of image holes. The purpose is to provide 1p of insulation+11 magnetic developer.In other words, the invention is to provide 1p of insulation+11 magnetic developer.
Insulating magnetic toner particles and a volume average particle size of 1.0 to 4.
Met m, the heating force φ to JOOoC is 0.5 wt-d% or less (), and the BET surface area by gas adsorption method is 15 m', /g' or more, and 11 Ce 02
) and 1 particle of seriform j1 as an ingredient. The present invention relates to an insulated +1 magnetic dry developer characterized in that it contains d-hydrated silicon oxide fine particles with a negative charge of +1. In the present invention, in order to improve the load marketability characteristic +J1 of the insulated outer magnetic sensor 11 (this I[iI lead organic rust compound is dispersed in the second resin). The zinc 411 airframe compound used is a load'municipal system?J
For example, zinc complex type monoamine is 100,000,000 or more.
There are lead complexes, etc., which are used in China and Germany, or can be used by combining 2 weighing amounts of 1-115. Normally, considering the blocking property and the offset resistance f'l, 1% is added to the OL based on the stone resin. In addition, examples of the 1111 lead organic compound include acetylacetate, zinc complex compound, EDTA zinc complex compound, and a7 torani+l.

[There are also IF lead lead body compounds, zinc picolinate complex compounds, etc. Negatively charged insulating magnetic toner to which zinc oxide (body compound) is added has improved triboelectric charging characteristics due to rubbing, but on the other hand, cohesiveness develops and Mf mobility tends to be low. Therefore, in the present invention, water-casting treated silicon oxide imitation particles are added to the developer as a fluidizing agent.The casting-treated silicon oxide fine particles impart fluidity to the toner particles, and
It supports negative chargeability and also acts as an abrasive during cleaning. The surface is treated with a ring agent or silicone oil and has excellent temperature resistance. In the present invention, the hydrophobized silicon particles used are preferably [7] Select 14 out of 20 pieces using a microscope and measure their diameter by 1llll.
The -order average grain 1γ is 05W or higher, the order is 1, and the average grain size is 3K or less. There is a dry method or a wet method for producing 11 gamma oxidized silicon imitates.In the case of the present invention, it is preferable to use the dry method I]. The hydrophobized silicon oxide fine No. 17 is preferably meta,
Hydrophobic silicon oxide fine particles having a degree of methanol hydrophobicity of 40% or more as measured by a nol titration test are used. Anhydrous silicon oxide (silica) is a typical example of the silicic acid fine powder to be hydrophobized. In addition, hydrophobized silicic acid 1N such as silicic acid resistant aluminum, silicate sl/sr'y L, silicic acid Kari J\, silicic acid Bugnesium, and zinc silicate can be applied. The amount of silicon oxide treated with divine wood is 001 to 3 layers per 100 layers of resistant toner.
2 cities) will be moderated. Examples of the hydrophobizing agent (a) organic silicon compound) used for surface hydration treatment include Hekiyoko methyl, /Silaza/, Tristylinlano, (1) Methylchlorosilane, Trimeo IL/Etoki,・Nran、Jimeirujijirorunra 7・Methylto 11guchi Jresila/, allyldimethylchlorosilane・, 7lylphenyldichlorosilane,
Hel'zyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane. β-Chlorethyltrichlorosilane, chloromethyldimethylchlorosilane, organosilylmercaptan, trimethylsilylmercaptan, triorga, nosilyl acrylate, vinyldimethylace[+disilane, dimethylethoxysilane, dimethyldimethoxysilano, diphenylshedkinsilano, hexamethyldineloxane , 1.
3-dihynylated I-ramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane centers per molecule, each of which is bonded to one Si at the end of the unit. There are dimethylpolyuroxanes containing hydroxyl groups. These are used in 81 combinations in one or two weighing quantities. These hydrophobized silicon oxide fine particles (@aqueous silica) are commercially available, such as R972, R-974, and R- manufactured by Aerosil.
976, RY-130, RY-200, RY-30
0, R-812; T-340 manufactured by Talco. Examples include T-500. Hydrophobization treatment When the degree of hydrophobization of shaft-based silica, which is a silicon oxide imitation grain, is hydrophobized to a degree of 40% or more as determined by the methanol drop test. The amount of triboelectric charge of the developer containing such fine silica powder becomes sharper and exhibits more uniform negative chargeability.
It's so sad. Here, the methanol titration test confirms the degree of hydrophobization of the silica fine powder having a hydrophobized surface. In order to evaluate the degree of hydrophobicity of the treated silica fine powder, the methanol titration test prescribed in the present invention is carried out as follows. Add 0.2 g of Rica fine powder to 50 mfl of water in a 250 mM Erlenmeyer flask. Methanol is titrated from the Hulet until the total amount of silica is 1/lf1. At this time, the solution in the flask is constantly stirred using a magnetic cooler. The end point is observed when the entire amount of fine silica powder is suspended in the liquid, and the degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached. An insulating magnetic toner whose negatively charged properties have been improved by the addition of a zinc organic complex compound has a strong tendency for silicon oxide particles to be easily attached to the toner particles due to electrostatic repulsion with the hydrophobically treated silicon oxide fine particles having negatively charged properties. Therefore, in the present invention, a specific oxidation cell 91. The particles are mixed into the developer. In the present invention, C, e02, which is one of the constituent components of the developer, is 1. The cerium oxide particles used as a component (not more than 50% by weight) have a volume f average particle diameter of 1.0 to 4.0 pLm (preferably 1.5 to 3.5 pLm) as measured using an Elzone Color/Tar.
JL), and the specific surface area by BET method is 15 m', /
g or less, and the temperature is roughly 20℃2 and the relative humidity is 90% or more]
- The material whose loss on heating up to 100° C. after being left for 72 hours in an environment of 0.5 wt% or less is used. The volume average particle size measurement in the present invention was carried out using an Erran counter using a 24 pm orifice. The Erran counter is similar in principle to the Coulter counter, but by having a large number of divided channels and using a small diameter orifice, it is possible to
It is possible to more accurately measure fine particle size fractions in the μm range. In addition, the measurement of the specific surface area by the BET method in the present invention is carried out using an automatic specific surface area measurement device, in which nitrogen gas (N2) is adsorbed onto a powder sample, and the amount of gas changed and sample * (heavy oil In the present invention, the heating loss to loOoo is measured by placing the particles in a desiccator (temperature: 20° C., relative humidity: 90% or higher) with humidity adjusted with ammonium chloride saturated solution. After leaving it for 72 hours, take about 50 mg as a sample and measure it without using a carrier gas, for example, using a DTA-TG (manufactured by Rigaku's Juuki, differential type differential thermal balance). The oxidized cellular J1 in the present invention contains CeO2 as a component [7] and also functions as an abrasive. Cerium oxide sludge is mixed in an amount of 0 to 5 parts per 100 parts of magnetic toner. Note that the CeO2 content of 4% is 50 tons v%.
If it is below, the ability as an abrasive during cleaning I will be low. Cerium oxide 1, in fact, contains a solubilized product of rank elements such as praseoxylate and lanthanum due to the manufacturing source 1. For example, a commercially available product is Mireek T (manufactured by 11 Metal Chogyo ■). Mireek (manufactured by Ikinzoku ■Gyo Co., Ltd.). ROXM-1 (manufactured by Tohoku Metal Chemical Ball Co., Ltd.). ROX M-3 (manufactured by Tohoku Konku Kagaku Ball). I can give you a hat. The oxidized seri internal particles used in the present invention have a volume average particle size of 1 to 4 ml as described above.
i When using cerium oxide J-grain r with an average particle diameter of 1μ or more, cerium oxide 1. As a result of the agglomeration of Koma''?f, the behavior as free particles (1) becomes low, and as a result, the IW stirring ability becomes low. 1) When the particle size is used, the gap between the hydrophobized silicon oxide fine particles 0') and the particles 1a becomes large, resulting in a low F ability to dissociate aggregates and agitation ability of the silica imitation particles. 7, the initial image density IW is low and the ability to suppress the γ-difference phenomenon is also reduced.Similarly, the heating speed outside the range specified by the present invention is 16 and the BET surface area is 1. In the case of cerium oxide 1X particles, the moisture resistance is inferior to that of cerium liquefaction itself, and the effect of the cerium oxide 1.97 particles contained in the present invention is also low. Sericum liquefaction is normal cerium hydroxide,
It can be produced by firing at a higher temperature than the firing temperature of 100%, pulverizing it, and then classifying it more strictly than conventionally. By adding specific cerium infusate particles to a negatively charged insulating toner containing a zinc 411 body compound and a hydrophobized silicon infusate material: (r), hydrophobized silicon infusate imitation particles E exhibits a strong negative 6.1 electric property, and for negatively charged insulating magnetic toner, it plays a good role not only as a fluidizing agent but also as a charging agent [1]. This can be inferred from the fact that when hydrophobic silicon oxide fine particles are added to a developer, the density is significantly lower than that of a developer without the addition.Also, in terms of the amount of developed grain, the hydrophobically treated silicon oxide fine particles When the toner is sufficiently stirred, the silicified silicon oxide fine particles are well dispersed between the toner particles, and the charge is sufficiently transferred to the toner.This allows the initial concentration to be reduced. 1. In the first direction, the prevention of standing up particles is achieved.When observed under a microscope, many aggregated toner souls and agglomerates of silicon oxide fine particles can be seen in the developer that does not contain cerium oxide particles. Seriu I
- In developers containing particles, such agglomerates are not observed or are very few. Furthermore, between the two, the latter promotes extremely good flow P1, and from this it can be understood that the cerium oxide particles have a function as a microdisperser that disperses fine silicon oxide powder into the toner well. I can do it. Observation of the toner surface depending on the presence or absence of small grains and cerium oxide particles shows that the adhesion state of the silicon oxide fine particles adhering to the toner is different from the early stage, and in the developer containing cerium oxide particles, the oxygen silicon present on the toner surface is The form of the fine powder is extremely finely dispersed, and it is observed that it is evenly distributed on the surface of the toner, whereas in a developer that does not contain particles of cerium oxide, fine particles of silicon oxide are distributed on a part of the surface of the toner. It is found that cerium oxide is unevenly distributed in a form similar to agglomerates.
, in a developer containing particles, cerium oxide wax containing silicon oxide fine particles around cerium oxide granules.
- is observed, so the oxidized seri 611 particles are able to loosen and disperse the agglomerates of such silicon oxide fine particles 1.
Further, it acts as a carrier for the silicon oxide fine particles, and the toner plays a role of supplying the silicon oxide fine particles. Therefore, 61. In the relationship between the load-charged toner and the load-heavy silicon oxide, the effect is particularly on the negatively charged silicon oxide fine particles, which dissolves their agglomeration and quickly transfers the negatively charged toner to the negatively charged toner. It is believed to supply fine grains of silicon oxide treated with wood. The reason why the cerium oxide particles act selectively on the silicon oxide fine particles rather than on the toner is probably because the silicon oxide fine particles have potentially higher negative charging ability than the toner. At the same time, the particle size of silicon oxide fine particles is closer to that of cerium oxide particles than that of toner, and JIE A11l
be done. These effects can occur, for example, if left unused for a long period of time.
In contrast, negatively charged toner and negatively charged silicon oxide imitation particles tend to separate (easily cause agglomeration, which may cause deterioration of the special P1, or to improve this, it is necessary to stir and mix the toner and silicon oxide fine particles again. If the IJ is left in the developing device, it is necessary to wait for it to be gradually recovered by an agitation device or the like in the developing device. On the other hand, in the present invention, in the case of a developer containing a specific cerium oxide (R), silicon oxide fine particles are quickly supplied into the negatively charged fI toner by the action of such a stirring device and cerium oxide particles, so that almost no deterioration occurs. This is consistent with the fact that the phenomenon of cerium oxide S71. It is desirable that the triho 7F charge of itself is low, and it is particularly undesirable to be strongly negatively charged.
It is preferable to have a triboelectric charging property of IQ+<1.5 when expressed in c/g). I. Riho' city freight is determined as follows. FIG. 1 is an explanatory diagram of an apparatus for determining the amount of tripoelectric charge of a sample particle r. First, A.
Trial to determine llI*1 particle capacitor 1J7-(200
~300 meshes) in a weight ratio of 1:9 (developer)
Add about 4g and cover with metal lid 4. At this time, the roux of the entire measurement container 2 is measured to be wl (g). Next, in the suction device 1 (at least the part in contact with the measurement container 2 is an insulator), suck from the suction " ] 7 and adjust the air volume control valve 6 to set the pressure cuff of the vacuum gauge 5 to 0 mmHg. In this state, it is sufficient ( Suction is performed for about 1 minute) to remove the sample particles. At this time, the potential of the electrometer 9 is V (volt). Here, 8 is a capacitor and the container is C (μF).
The amount of spray in the entire measurement container after suction is defined as the weight W2 (g). The trypocharge amount (μC/g) of this sample particle is calculated as shown in formula F. Ij4 L, Al11 constant conditions are 23℃150%RH
shall be. In addition, the carrier (iron powder) used for measurement is 200 to 30
Although the carrier is 0 mesh, in order to eliminate errors, the carrier is sufficiently suctioned with a steam suction device, and the carrier that passes through the 400 mesh screen is removed before being mixed with the sample particles. As the binder resin for the toner used in the present invention, any known binder resin can be used. For example, polystyrene L・N, polyp-
Chlorstyrene, polystyrene, poly(hinyl), etc., styrene and its substituted compounds in the middle, methylene-p-chlorostyrene? Coalescence, styrene-propylene copolymer, styrene-hinyltoluene copolymer, nutyrene-hinylnaphthalene copolymer, styrene-acrylic methyl copolymer, styrene-acrylic ethyl copolymer 1f, styrene-
acrylic butyl copolymer, styrene/methacrylic octyl copolymer, styrene/methacrylate ethyl copolymer, styrene/butyl methacrylate copolymer, styrene-α-chloromethacrylate copolymer Styrene-acrylonitrile J (polymer, styrene-acrylonitrile methyl ether polymer, styrene-acrylonitrile ethyl ether copolymer,
Styrene-hinyl methyl ketone, polymer, styrene-isoprene copolymer, styrene-7crylonitrile mono/dene copolymer, styrene-maleic acid copolymer, styrene-maleic acid hafester, lI [combined, Su4 Shi・7・-ma'/Ia esterba polymer '9's streak/Polymer to yarn; Pojl Methyl Methyl V-1, Polybutyl Methacrylate 1, Poly 1! Hinyl L, polyl
Hinyl 1i1 acid, polyethylene 1/one, polypropylene, polyester 1 polyurethane, epoxy resin, polyhinyl butyral, boriamy I, polyacrylic resin, rosin, modified +'l rosin, terpeno resin, phenolic resin, aliphatic resin They can be used alone or in combination, such as alicyclic hyal, hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraine, and wax. Among them, styrene dead phase (1h, styrene-acrylic) t-butyester resin, styrene-metallic ester resin and U-polyester resin are preferable in terms of developability and durability. The particles W containing the magnetic PI material on the side of the fixing resin and turned into afro magnetic toner have a volume of 11 uniformly 1 nia.
Lines 5-30. It's cute. Load city t' according to the present invention
+ Insulating toner retains trifocal charge and provides sufficient development.
In order to check the electrostatic transfer properties, the number is 1010Ω'cm.
1 or more, preferably 1QI3Ω・cm or more 1 (preferably z negative resistance is 1.1 ferromagnetic material as the magnetic material contained in I) C and alloys containing these, magnetite ,-\Makuito,
Compounds such as iron such as ferrite, cobalt, nickel manganese, and other ferromagnetic alloys 1 can be used as appropriate. The particle size is 100-800mpif, preferably 300mpif.
-500m JL, preferably 1 part from 30 to 100 tons per 100 tons of camellia resin, more preferably l:j:
It is preferable to contain 40 to 90 parts. Furthermore, in the magnetic toner according to the present invention, the surface]
0, I, -10 ton M for the binder resin lOOΦ.
It is very preferable to add part C (0.5-8 i g part). The toner of the present invention is prepared by kneading 44 toner particles using a heat roll, kneader, extruder, etc., and then mechanically crushing and classifying the toner. (Method 1) Alternatively, a method in which a material such as magnetic powder is dispersed in a binder resin solution and then spray-dried; A polymerization method in which a toner is produced by polymerizing an intermediate in a suspension prepared by mixing a specified material with a dispersion stabilizer and adding it to an aqueous medium containing a dispersion stabilizer, and a toner manufacturing method, etc. The method can be applied.Also, recently, microencapsulated toner has been proposed for the purpose of separating the functions of toner, etc., but the present invention can be applied by satisfying the requirements of the present invention.Furthermore, the present invention can be applied. As a method for mixing the inorganic and all-inorganic fine powder, there may be used a known mixing machine, such as a V-type mixer, a rotary container mixer such as a tarpaulin mixer, a ribbon type, a screw type, a single-rotation blade type, or other fixed type mixers. Container-type lj@plywood can be used as appropriate.Also, 1.7 of the three components may be mixed at once during mixing, or they may be mixed in an order taking into consideration the properties of the toner. Furthermore, it is also possible to further mix a known fourth component. For example, polyethylene fluoride, polyhynyldene fluoride, fatty acid metal salts, various ω polishing agents, etc. The present invention will be described in Examples and Comparative Examples below. Although the present invention is not limited in any way by Jt-specific explanation, Example 1 The four components of the formulation described in 1-1 were melt-blended, cooled, and then crushed and classified to obtain particles with a particle size of 5 to 5. 20. (Volume/average particle size approximately 12p,) c7
) Insulating magnetic 1ner (?lt% resistance (+n10150・
c, m). To 100 parts by weight of the obtained insulating magnetic toner were added cerium oxide particles containing about 65% of eroded IW, 0.4 double contact area of hydrophobic silica with an average primary particle size of 0.15μ, and 80% by weight of CeO2 component. [Elzone Power/Tar(
(manufactured by Particle Data Co., Ltd.) by volume average particle size 2.
74 River, loss on heating up to 100°C after moisture absorption: 0.14% by weight, BET specific surface area: 3 as measured by automatic fl+1 determination device 2200 model (manufactured by Shimaoki Seisakusho) by nitrogen gas adsorption
．． A developer was prepared by mixing 1 weight part (6 m2/g). When this developer was applied to a commercially available threaded paper copying machine (NP-400 manufactured by Canon) and images were obtained by continuously copying 500 sheets, the reflection density of the images was 1 as shown in the graph in the accompanying drawing.
1.38゜20th 1.37.50th 1.37,
100th sheet 1.40, 500th sheet 1.40 and first 1111
The image density during copying was stable (1.39 in terms of reflection density throughout), and an extremely clear image was obtained without fogging. (32,5°C 190%) and low temperature low i5i! (15°
Even under an environment of 0.010%), the developing characteristics were as good as those under normal temperature and normal humidity. Examples 2 to 6 Cerium oxide was prepared in the same manner as in Example 1, except that cerium liquefaction particles Y shown in Table 1 below were used. A developer was prepared. The results of the image forming test conducted in the same manner as in Example 1 are shown in Table 2. Table 1 Example 7 A developer was prepared in the same manner as in Example 1, except that 0.4i part of hydrophobic silica with a hydrophobic composition of about 50 and an average primary particle size of 0.25 was used. . The results of the image formation test are shown in Table 2. Example 8 Styrene-2-methylpentyl mekuri L--1-copolymer (Jt-combination@quantity ratio 6:4; Mw=
A developer was prepared in the same manner as in Example 1, except that 100 parts by weight of 260.000) was used. The results of the image formation test are shown in Table 2. Example 9 Styrene-n-butyl methacrylate as a binder
Maleic acid monobutyrate copolymer (copolymerization ratio 60:3
A developer was prepared in the same manner as in Example 1, except that 100 mw (5:5; Mw = 350.0OO) was used. The results of the image formation test are shown in Table 2. Example 10 A developer was prepared in the same manner as in Example except that 2 parts by weight of alkyl salicylbutyroZn complex was used as a charge control agent. The results of the image formation test are shown in Table 2. Comparative Example 1 100 overlapping parts of the magnetic toner prepared in Example 1 without blending cerium oxide particles with hydrophobization of about 65% and average primary particle size of 0. , l 5. A developer was prepared by mixing with 0.4 type part of hydrophobic silica, and an image forming test was conducted in the same manner as in Example 1. As shown in the graph in the attached drawing, the reflection density was 1.
l 3, 20th sheet 1.03, 50th sheet 0.88.1
00th sheet 0.91. , 5.00 sheets, 141.11, and the image density was low, and a falling phenomenon was observed. Comparative Example 2 To 100 parts by weight of the magnetic toner prepared in Example 1, 0.00% of non-hydrophobicized silica with a degree of arborization of O5 and an average particle size of 0.25 μm was added.
4frJ part and volume average t! 'I diameter 3
．． 25 IL, heating reduction at 1001'O after moisture absorption ji+
2.3 tons %, specific surface area by BET method 39. om2
/g (outside the specified range of the present invention) of CeO2 of 63.2
A developer was prepared by mixing with 1 part by weight of cerium oxide particles containing % by weight. As is clear from the graph shown in the attached drawing, the number of copies is 50~
At the point of 100 sheets, a noticeable drop in price was observed. Comparative Example 3 Volume average particle size 1647z by Elsohn, 1 after moisture absorption
Specific surface area according to BE"IIJ: 8.1 m 2
/g Softened Japanese seri 9 containing 5I% of CeO2
Example 1 except that 1 part by weight of 11 particles was used.
A developer was prepared in the same manner as above. The test results are shown in Table 2. Comparative Example 4 Volume average particle size of 1.47 particles by Elune, 1 after moisture absorption
Heating star reduction 150@φ% at 00℃, by BET method. L
I4 surface area 18.1 m 2 / g
A developer was obtained in the same manner as in Example 1, except for using 1 part by weight of cerium oxide particles containing 80% by volume. The test results are shown in Table 2. Comparative Example 5 CeO2 having a volumetric average particle diameter of 4: 52 p, heating at 100'C after moisture absorption, i4% by weight, and a specific surface area of 1.8 m2/g by BET method was 51,
A developer was prepared in the same manner as in Example 1, except that one part of the cerium oxide particles containing 8 parts by weight was used. The test results are shown in Table 2. Comparative Example 6 Elsohn volume average particle size 0.91μ, 1 after moisture absorption
CeO2 with a specific surface area of 9.5 m 2 / g by heating decay rate 0.08 modified v% 1 BET method at 00°C is 72.
A developer was prepared in the same manner as in Example 1, except for using cerium oxide containing 5% by weight and 1 f-1 early part. The test results are shown in Table 2. 1L Comparative Example 7 A developer was obtained in the same manner as in Example 1, except that 0.4 i part of non-hydrophobized silica with a degree of hydrophobization of o, qi uniform particle size of 1o, and t5μ was used. The test results are shown in Table 2. In Examples 2 to IO in Table 2, there was virtually no initial rise in image density, the reflection rate was stable from the beginning to the end, and extremely clear images without fog were obtained. -7, the initial image density also decreased significantly, and from the initial to the 50th sheet, the density decreased by about 0.3 or more per reflection density in all cases, and in the examples of the present invention. Compared to the case with Capri, the image quality was noticeable, blurry, and with poor resolution. This reveals that the effect of the developer of the present invention is very significant.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an apparatus for measuring the amount of tripo charge. FIG. 2 shows Example 1. 3 is a graph showing the relationship between the number of durable sheets and image reflection density for the developers of Comparative Examples 1 and 2. ! -------Suction machine, 2-------1 measurement container. 3 ----m-screen, 7 ----1--suction [''. 8 ------- Capacitor

Claims (2)

[Claims] (1) Negatively charged insulating magnetic toner particles containing at least a binder resin, a magnetic substance, and a zinc organic complex compound, having a volume average particle diameter of 1.0 to 4.0 μm, and having a heating loss of up to 100°C. 0.5% by weight or less, a BET specific surface area measured by nitrogen gas adsorption method of 15 m^2/g or less, and cerium oxide particles whose main component is CeO_2, and negatively charged hydrophobized silicon oxide fine particles. An insulating magnetic dry type developer comprising: (2) Claim 1 containing 0.1 to 5 parts by weight of cerium oxide particles and 0.01 to 3 parts by weight of hydrophobized silicon oxide particles per 100 parts by weight of negatively charged insulating magnetic toner particles. The insulating magnetic dry developer described in .