JPH01202764A - Carrier for development of electrostatic latent image and its production - Google Patents

Abstract

PURPOSE:To obtain a carrier for development of electrostatic latent image having appropriately high electric resistance and high durability and being able to secure an amt. of stable triboelectricity by covering particles of core material for the carrier with a resin and sticking fine inorganic particles having reverse polarity of charge fixedly to the surface of the covering layer. CONSTITUTION:Particles of a core material for a carrier are covered with a resin and fine inorganic particles having a polarity reverse to the polarity of the particles are stuck fixedly to the surface of the covering layer. Thus, the resin and the fine inorganic particles are exposed on the surface of the carrier in a state of mixture with each other. Accordingly, a thickness of the covering layer on the surface of the core material of the carrier and a proportion of the covered part can be set optionally basing on a proportion of the core material to the fine particles of the inorganic material to be mixed. Thus, a carrier for the development of electrostatic latent image having high electric resistance as well as having appropriate electroconductivity partly is obtd. Therefore, a carrier having stable amt. of triboelectricity, high durability and high moisture resistance is obtd.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a developer for developing electrostatic latent images in electrophotography, electrostatic recording, and electrostatic printing, and particularly to a developer for electrophotography using a two-component magnetic brush development method. This invention relates to a developer carrier for copying machines and printers, and a method for producing the same. Conventional Technology To obtain an image using an electrophotographic copying machine or printer, the surface of a photoreceptor, which is an image carrier, is first uniformly charged, and then this is exposed to light based on a pattern corresponding to the image on the original, or the output is The contents of the image are written onto the photoreceptor using light to form an electrostatic latent image. Next, the surface of the photoreceptor having this electrostatic latent image is developed (visualized) using a developing device, and the obtained toner image is transferred to a transfer material such as paper. In such a developing device, a magnetic brush made of a magnetic carrier with toner adhered to the surface is formed on the surface of the developing sleeve by magnetic force, and this is brought into sliding contact with the surface of the photoreceptor to develop an electrostatic latent image on the surface of the photoreceptor. The most common method is to Conventionally, such a developer has an average particle size of 20 to 200 μm.
A mixture of a magnetic carrier made of shoulder-sized iron powder particles and an insulating toner having an average particle diameter of about 5 to 20 μm is used. However, the volume specific electrical resistance of the carrier is as low as 08Ωcn+ or less. Therefore, when the toner concentration in the developer decreases due to continuous use or the like, the charge on the electrostatic latent image carrier escapes through the carrier, causing disturbances in the latent image or defects in the image. Further, there is a problem that carriers adhere to the image area of the electrostatic latent image carrier due to charges injected from the developing sleeve. Further, since the carrier particles are hard, if they adhere to the electrostatic latent image on the photoreceptor, the surface of the photoreceptor will be damaged by a blade cleaner or the like when cleaning the surface of the photoreceptor. In order to solve this problem, it has been proposed to coat the carrier surface with resin to increase the electrical resistance of the carrier (for example, Japanese Patent Laid-Open No. 60-66264, Japanese Patent Laid-Open No. 60-662625, JP-A-57-660, JP-A-60-60658, etc.). Problems to be Solved by the Invention Such a carrier is generally obtained by dissolving a resin in a solvent and coating carrier particles with a solution obtained, followed by drying. Therefore, since the particle surface of the carrier is completely covered with resin etc., charge accumulates, making it difficult to control the image quality, and the solvent may remain in the coating layer of the carrier, or the coating film may be thin. There are problems such as low electrical resistance. In order to solve this problem, it is possible to increase the electrical resistance of the carrier by increasing the thickness of the coating film on the surface of the carrier, but such a method requires repeating the coating process many times, which increases costs. is unavoidable. Further, the chargeability of the carrier is very unstable, and the amount of charge increases with repeated copying, resulting in a problem that sufficient image density cannot be obtained. Another problem with the resin coated carrier is that the material of the resin coat must be changed depending on whether it is used in combination with positively charged toner or negatively charged toner. The required charging polarity of the toner varies depending on circumstances such as the polarity of the photoreceptor used and whether the developing system is reverse or forward rotation. - Numerically, two types of developers with positive and negative toner charging polarities are prepared, and a developer with a polarity suitable for the system is selected. However, in such cases, it is necessary to prepare two types of resin coated carriers.
This causes an increase in costs. On the other hand, the toner is carried along with the carrier to the electrostatic latent image area by the developing sleeve, and is then separated from the carrier surface and electrostatically adheres to the latent image area to visualize the latent image. At this time, since a so-called edge effect exists, it is not possible to obtain a negative-like black background over a wide area only by self-biasing using a latent image, and it is necessary to control the image quality by applying a bias voltage from the outside. That is, in order to apply a -like and effective bias electric field, it is desirable to impart partial conductivity to the carrier surface. However, conventionally, it has not been possible to obtain a carrier that has high electrical resistance as a whole and is partially conductive. That is, when iron powder, ferrite, or the like is used as a carrier and used as it is without any treatment, it is possible to apply a bias voltage, but the electrical resistance value is low and the life as a carrier is short. The present invention provides a carrier for developing electrostatic latent images that has a moderately high electrical resistance, can ensure a stable amount of triboelectric charge, is partially conductive, and has excellent durability, and the carrier. The purpose is to provide a manufacturing method. Another object of the present invention is to provide a carrier that can be used with toner systems of two types of polarity, positive and negative, and a method for producing the carrier. Means for Solving the Problems The present invention provides an electrostatic latent image characterized in that carrier core material particles are coated with a resin, and inorganic fine particles having opposite charge polarity are fixed to the surface of the coating layer. The present invention provides a developing carrier and a method for producing the same. The carrier for developing electrostatic latent images obtained in the present invention is composed of carrier core particles coated with a resin and inorganic fine particles having a charge polarity opposite to that of the resin and fixed to the resin coating layer. In order to manufacture the carrier of the present invention, which is characterized in that the resin and inorganic fine particles are mixed and exposed on the carrier surface, first, the carrier core particles are coated with a resin and an intermediate coat layer is formed. form. To form such an intermediate coat layer, the resin is dissolved in a solvent in the same manner as in the production of known coated carriers, and the resulting solution is coated on carrier core particles by spray drying, fluidized bed, transfer fluidized bed, etc., and dried. do. Alternatively, in order to coat the carrier core material with polymer particles, van der Waals forces and By the action of electrostatic force, polymer particles are attached to the surface of the carrier core material to form a coating layer of fine particles, and then heated and melted, or the polymer particles are softened by a local temperature increase caused by mechanical impact force, etc. Alternatively, a part of the polymer may be dissolved in a solvent, or a resin may be dispersed in a solvent and then spray-dried to form a film using a spray drying method to obtain a carrier having an intermediate coat layer. Next, inorganic fine particles having a charge polarity opposite to that of the coat layer are fixed to the surface of the carrier having the obtained intermediate coat layer (resin coat carrier). Such fixation can be achieved either by adding the resin-coated carrier to the inorganic fine particles and mechanically mixing them in the same way as in the formation of the intermediate coat layer to adhere the fine particles, and then melting and fixing the intermediate layer by heating, or by fixing the intermediate layer by heating it. The particles are fixed by dissolving them in a solvent to form a coating layer made of inorganic fine particles on the surface of the coated carrier. It should be noted that the heating means used for fixing the particles is not particularly limited. By further stirring or applying pressure during melting, the fixation of the coated particles becomes more uniform and reliable. Further, the immobilization may be performed in the presence of an inert gas such as nitrogen. The coated carrier thus obtained is sieved to remove aggregates and used as a carrier. According to the method of the present invention, a powder consisting of a carrier core material with a large particle size and a polymer fine particle powder with a small particle size, preferably mechanically crushed fine particles, are mixed to form large particles by mechanochemical action. An intermediate coating layer of small particles is formed on the surface to further fix inorganic fine particles, and the carrier core material is coated using powder with small particle size. According to the present invention, the thickness of the coating layer on the surface of the carrier core material and the ratio of the coating portion can be arbitrarily set by adjusting the mixing ratio of the carrier core material and the fine particle powder, making it possible to easily create a carrier with high resistance. It can be prepared. Furthermore, since the present invention directly coats the carrier core material using powder, a stable coating layer can be easily obtained at low cost. Furthermore, the carrier of the present invention has excellent durability because no solvent remains in the coating layer and no pores are formed due to evaporation of the solvent. Carrier core materials that can be used in the present invention include metals such as iron, nickel, and cobalt, and alloys thereof, metal oxides such as iron oxide and ferrite, and composite core materials whose main components are resin and magnetic powder. , and mixtures thereof. Commercially available carrier core materials include:
For example, FMC-6 (manufactured by TDK Corporation);''-25
0HR (manufactured by Nippon Iron Powder Co., Ltd.), X-012 (manufactured by Fuji Electrochemical Co., Ltd.), KG-200 (manufactured by Kanto Denka Co., Ltd.), K
Examples include G-201 (manufactured by Kanto Denka Co., Ltd.) and KM-200 (manufactured by Kanto Denka Co., Ltd.), but are not particularly limited. These core material particles have a particle size of 20 to 200 μm, preferably 30 μm.
~100 μm is used. When the particle size of the carrier core material is smaller than 20 μl, the transportability and charging performance are poor, and the carrier tends to adhere to the photoreceptor, making it difficult to use. On the other hand, if the particle size of the core material particles is larger than 200 μm, the image obtained using such a carrier will have a rough and rough texture. According to the present invention, even if a carrier core material having a small particle size of about 30 to 80 μm is used, a uniform coating layer can be obtained, and a carrier with stable electrical resistance and chargeability can be obtained. The intermediate coat resin coated on the carrier includes vinyl resin, styrene resin, acrylic resin,
Methacrylic resins, polyester resins, epoxy resins, rosin-modified phenol-formalin resins, cellulose resins, polyether resins, silicone resins, fluororesins, etc. can be used, and mixtures thereof may also be used. Furthermore, when resin particles are directly mixed with core material particles and fixed by heating, resin particles obtained by coarsely pulverizing, then finely pulverizing and classifying are preferable. The softening point of the polymer used for the intermediate coat is preferably about 80 to 140°C. The layer thickness of the carrier core Murakami intermediate coat layer is 0.5 to 5 μl.
is preferred. Next, the inorganic fine particles to be fixed to the surface of the intermediate coat layer have a chargeability opposite to that of the intermediate coat layer, and the average charge level of the intermediate coat layer and the inorganic fine particles is approximately between the positively charged toner and the negatively charged toner. The one that is located is the best. A semiconductive material having an electrical resistance value of 10' to 10I0Ω·C, more preferably 105 to 10’Ω·C is preferable. The positively charged toner and negatively charged toner mentioned here refer to general toners, such as toners made of materials containing styrene acrylic resin, carbon black, a charge control agent, and optionally additives such as wax. Can be mentioned. As the charge control agent, a nigrosine dye is used for positively charged toners, and a chromium-containing metal dye is used for negatively charged toners. Regarding the number of dyes contained, resin 10
2 to 8 parts by weight is common compared to 0 parts by weight. In addition,
In order to describe the chargeability of carriers, standard positive and negative toners are shown here, but toners are not limited to these compositions, and may include chargeable resins with polar groups or charge control agents other than the dyes mentioned above. It may be a toner that has substantially the same charge level as the above-mentioned positive and negative toners. Next, the inorganic fine particles combined with each intermediate layer will be described. For the intermediate layer made of a resin having (-) chargeability such as polyester, Fe-Zn-based ferrite fine particles, F, which are inorganic fine particles having (+) chargeability, are used.
e-Mg type ferrite fine particles are preferable. In addition, these divalent metals of Zn1Mg may be used alone or in combination,
Further, it may be used in combination with other divalent metals that are commonly used in ferrite. Among the ferrite fine particles, F is particularly preferable.
Examples include e-Zn-based ferrite fine particles. The particles have high (+) chargeability, are stable, have good compatibility with polyester resins, and are relatively inexpensive. As a method for producing ferrite fine particles, for example, Japanese Patent Application Laid-Open No. 55-654
Examples include methods described in Japanese Patent Publication No. 06 and Japanese Patent Publication No. 57-19055, but are not limited thereto. In addition, examples of other inorganic fine particles that are compatible with the resin intermediate layer having a chargeability of <(-), such as polyester, include neutral (p
Examples include magnetite fine particles H6-8). This is considered to be because the magnetite fine particles exhibit relatively (+) chargeability. In addition, to measure the pH of metal oxide fine particles, put each metal oxide fine particle in ion exchange water in an amount of 100 g/(2), stir, then let stand, measure the pH of the supernatant, and measure the amount of residual alkali or acid. In addition, the resin exhibiting (=) charging property is not limited to polyester resins, and examples thereof include fluorine acrylic resins, polyethylene resins, polypropylene resins, etc. The preferred polyester resins used in the present invention are , can be obtained by a polycondensation reaction of a diol having a bisphenol structure and a polyhydric carboxylic acid or its anhydride.The diol has the following general formula (1) [wherein R is ethylene or propylene, A and B is a positive integer, and the average value of the sum is 2 to 7.] Etherified bisphenol represented by the formula B is a positive integer, and the average value of the sum is 2 to 7. It may be a polyester resin manufactured by containing up to about 10 mol%. Examples of polyols without a bisphenol structure include ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, neopentyl glycol, sorbitol, etc. Aliphatic polyols include cyclic polyols such as sorbitan. Examples of polycarboxylic acids include fumaric acid, maleic acid, maleic anhydride, phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, trimellitic acid, Examples include trimellitic anhydride, alkylsuccinic acid, alkenylsuccinic acid, etc. In the polycondensation reaction, usually no reaction solvent is used, or an organic inert solvent such as benzene, toluene, xylene, etc. is used, and the catalyst For example, tin oxide, zinc oxide, titanium oxide, dibutyltin dilaurate, etc. are used.The ratio of the number of hydroxyl groups in the diol composition to the number of carboxyl groups in the polycarboxylic acid composition is:
It is generally between about 1.2 and 0.8, but is not particularly limited. When synthesizing polyester, it is preferable to sample a portion of the reaction product over time, measure the softening point, and stop the reaction when the desired softening point is reached. In addition, the softening point here means the ring and ball softening point measured according to the measuring method prescribed|regulated to ASTM-E-51T, and is 80-180 degreeC in this invention. Furthermore, the acrylic resin used in the present invention has the following general formula (■): CHt = CC00Rt (II) [wherein <R is hydrogen, methyl, and R1 is CnH-n-+ (however,
n is an integer of t-tS), an acid group, a hydroxyl group, or a phenyl group]. Examples of such acrylic resins include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, and tert acrylate.
-butyl, amyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate,
Dodecyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, n- methacrylate Alkyl acrylates or alkyl methacrylates such as octyl, decyl methacrylate, dodecyl methacrylate, and stearyl methacrylate; Phenyl acrylates such as cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, benzyl acrylate, and benzyl methacrylate; phenyl methacrylate, etc.; hydroxyl acrylate or methacrylate such as β-hydroxyethyl acrylate, diethylene glycol acrylate, polyethylene glycol acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, diethylene glycol methacrylate, polyethylene glycol methacrylate; or It may be a single type of methacrylic acid, acrylic acid, or the like or a copolymer of two or more types. In addition, styrene such as styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-dodecylstyrene, etc. It may be a derivative or a copolymer with vinyl acetate, vinylnaphthalene, vinyl methyl ether, vinyl ethyl ether, etc., and is not particularly limited. The polymerization method is not particularly limited, such as solution polymerization, suspension polymerization, and bulk polymerization. When used as a polymerization initiator, examples include benzoyl peroxide, lauroyl peroxide, 2.2'-azobisisobutyronitrile, 2.2'-azobis-(2゜4-dimethylvaleronitrile), etc. . On the other hand, compared to styrene acrylic and acrylic (+)
An acidic (pH 4 to
6) Magnetite fine particles are preferred. These inorganic fine particles have particle diameters of 0 and O1 to 8 μm. If the particle size is larger than 8μ, a good coating layer will not be formed on the surface of the carrier core material;
If it is smaller than the shoulder, it will be difficult to disintegrate the -order aggregate and the dispersibility will be poor. The mixing ratio of the carrier core material and the inorganic fine particles is 0.05 to 30 parts by weight of the inorganic fine particles to 100 parts by weight of the carrier core material.
Parts by weight, preferably 0.5 to 15 parts by weight. If the proportion of the inorganic fine particles is less than 0.05 parts by weight, the effect of the inorganic fine particles will not be noticeable and the chargeability of positive and negative toners will be poor, while if it is more than 30 parts by weight, aggregates of inorganic fine particles will be mixed. Undesirable. Therefore, it is preferable that the inorganic particles have an electrical resistance value of to'-10'' ΩcII+ or less.A specific device that can be used to fix the inorganic fine particles by adding the intermediate coat layer is a stirrer. Autoclave with spiral flow (manufactured by Freund Sangyo Co., Ltd.),
Typical spray drying equipment, impact reforming machines combined with thermal treatment (for example, Nara Hybridizer (manufactured by Nara Kikai Seisakusho Co., Ltd.), Ong Mill (manufactured by Hosokawa Micron), Mechano Mill (manufactured by Kaida Seiko Co., Ltd.)), etc. It will be done. In this way, the inorganic fine particles fixed on the coated carrier form a strong coating layer, impart appropriate conductivity to the carrier, and are effective in preventing charge accumulation on the carrier. The electrical resistance of the obtained carrier is 107 to 10149 cm, preferably 108 to 10'3 Ωcm. Therefore, a particularly preferable carrier obtained by the method of the present invention is as follows: (1) The surface of the carrier core material particles is coated with a resin, and the surface of the coating layer has a charge polarity opposite to that, and an electrical resistance value of 1.
It is a carrier characterized by fixing inorganic fine particles having a resistance of 05 to 1010 Ω・CjI or less, and the average charge level of the carrier is approximately between the charge levels of positively charged toner and negatively charged toner, and it is a positively charged toner type. and negatively charged toner systems. (2) The carrier according to item 1 above, wherein the resin is a polyester resin and the inorganic fine particles are Fe-Zn ferrite fine particles. (3) The polyester resin [wherein R is ethylene or propylene, each AlB is an integer of 1 or more, and the average value of A+H is 2
~7] It is obtained by cocondensation polymerization with a diol component represented by the formula and a carboxylic acid component consisting of a divalent carboxylic acid or a lower alkyl ester thereof, and has a softening point of 80 to 180°C and an acid value (A
2. The carrier according to item 2, wherein V) is 10 to 50. (4) The carrier according to item 1 above, wherein the resin is a polyester resin and the inorganic fine particles are neutral (pH 6 to 8) metal oxide fine particles. R3 (5) Acrylic resin CHt = CCOORx [
In the formula, R1 is hydrogen, a methyl group, and Rt is Cn Ht n
*l (where n is an integer of 1 to 18), or an acid group, a hydroxyl group, or a phenyl group], and the inorganic fine particles are acidic (pH 4 to 6).
) The carrier according to item 1 above is a metal oxide fine particle. In the case of the above-mentioned combination of inorganic fine particles and resin-coated intermediate layer, it was possible to impart an optimal charging fi (10 to 20 μC/9) to both positively charged toner and negatively charged toner with good rise. , The reason is presumed as follows. First of all, the average charge level of the resin intermediate layer and the inorganic fine particles is approximately equal to the median value of the charge level of the (+) toner and the charge level of the (-) toner. Second, the electrical resistance value of the inorganic fine particles is 105 to 10I0Ω・c
m is relatively low compared to resin, and charges in the carrier do not accumulate more than necessary. Third, a micro-distributed electric field is generated between the resin intermediate layer and the inorganic particles distributed like islands on its surface, and charge exchange occurs between the inorganic particles and the toner by injection in addition to triboelectric charging. Although the mechanism is not clear, the start-up of toner charging habit,
This seems to be advantageous for saturation. Because of these characteristics, the carrier having the coat layer of the present invention is excellent in providing stable charge to both positive and negative toners. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

[Career evaluation]

The physical properties of the carriers obtained in Examples and Comparative Examples were measured and evaluated by the following method. (1) Carrier particle size The carrier particle size is Microtrac model 7995-
10SRA (manufactured by Nikkiso Co., Ltd.) was used to determine the average particle diameter. (2) Measurement of electrical resistance of carrier The electrical resistance was measured as follows: Place the sample so that it has a diameter of 50 mm, a mass of 895.4 g, an electrode with a diameter of 20 mm, and an inner diameter of 38 mm.
A guard electrode with an outer diameter of 42 mm (mm1) was placed thereon, and the test was carried out after 1 minute of applying a DC voltage of 500 V. The measurement environment is a temperature of 25 degrees V.
At a C1 relative humidity of 55±5%, measurements were repeated five times and averaged. (3) Frictional charging properties and printing durability test [Toner preparation] (-) Chargeable toner glass transition point 60'C) Carbon black 5 (manufactured by Mitsubishi Kasei Corporation: MA#8) (+) Chargeable toner glass (Transition point: 60°C) The above materials were thoroughly mixed in a ball mill, and then kneaded on three rolls heated to 140°C. After the kneaded material was left to cool, it was coarsely ground using a feather mill and further finely ground using a jet mill. Thereafter, air classification was performed to obtain a fine powder with an average particle size of 13 μm. The respective polar toners are hereinafter referred to as toner A ((-) chargeable toner) and toner B ((+) chargeability toner). The average particle size of the toner can be measured using a Coulter counter.
(manufactured by Coulter Counter) to measure the relative weight distribution by particle size in a 100 μl aperture tube. (When Toner A is used) 48 g of Toner A and 552 g of carrier are placed in an IQ polyethylene container, and mixed and stirred by rotating on a stand for 5 hours. Using this, a printing durability test of 50,000 copies was conducted using a copying machine EP-870 (manufactured by Minolta Camera Co., Ltd.) having a sleeve rotation type developer. (When Toner B is Used) 50 g of Toner 8 and 450 g of carrier are placed in an IQ polyethylene container, and mixed and stirred by rotating on a stand for 5 hours. Using this, a printing durability test of 50,000 sheets was conducted using a copying machine EP-470Z (manufactured by Minolta Camera Co., Ltd.) having a sleeve rotation type developer. Using Toner A and Toner B, the amount of charge was measured at the initial stage and during the printing durability test (1,000 sheets, 5,000 sheets, to, 000 sheets, 30,000 sheets, and 50,000 sheets). Furthermore, image fog during the printing durability test was visually observed and ranked based on the following image quality evaluation criteria. ◎: No fogging even when printing 50,000 sheets ○: Almost no fogging for commercial use △: Fogging is noticeable but is acceptable for practical use. ×: Fog is noticeable and is not practical. Table 1 (Inorganic particles) a Ferrite MFP-2TDK Co., Ltd. b Ferrite MFP-4TDK Co., Ltd. C Ferrite X703
Fuji Electrochemical Co., Ltd. Example 1 (i) Production of coat carrier (a) Bisphenol type polyester resin (softening point 123°C,
Glass transition point 65°C, AV21.0HV43, Mn
: 7.600. Mw: 18L400) was finely pulverized using a jet pulverizer and then classified using an air classifier to obtain polymer particles having an average particle size of 2.8 μm. Next, iron powder T E F V 250/400 (manufactured by Nippon Tetsuko Co., Ltd., average particle size 50μ, electrical resistance 3.2X1) was used.
0 BΩcm, true specific gravity 7.6)) and 3 parts by weight of the polymer particles were mixed for 5 minutes at 10.00 Orpm using a multi-blender mill (manufactured by Nippon Seiki Seisakusho Co., Ltd.), and then mixed with a stirrer. Autoclave TA
S-1 (manufactured by Pressure Glass Industry Co., Ltd.). This was stirred for 3 hours (700 rpm) at a temperature of 200°C under nitrogen pressure (30 kg/am”), and the resulting particles were sieved (sieve opening = 105 μm) to remove aggregates and coated. Carrier (a) was obtained. (ii) Coating of inorganic particles 1000 parts by weight of the coated carrier (a) and inorganic particles (e) (magnetic powder EPT-1000, Toda Kogyo Co., Ltd.)
(manufactured by Nippon Seiki Co., Ltd.) for 10 minutes at 2,000 rpm using a homogenizer (manufactured by Nippon Seiki Co., Ltd.), and then treated in an autoclave in the same manner as above. The obtained particles were similarly sieved to obtain carrier (2). Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 2 1000 parts by weight of the coat carrier (a) of Example 1 (i) and inorganic particles (a) (ferrite MFP-2, TD
2 parts by weight of K Co., Ltd.) was added to Mechano Mill (Kaida Seiko Co., Ltd.).
After mixing for 10 minutes at 400 rpm using
Heat treatment was performed using an instant heat treatment device. The obtained particles were sieved (105 μj+) to remove aggregates, and the carrier
I got it. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 3 (i) Production of coated carrier (b) Ferrite carrier FMC-6 (average particle size 44μ shoulder, T
Example 1(i) was prepared using 1000 parts by weight of DK Co., Ltd. and 30 parts by weight of polymethyl methacrylate MP-5000 (average particle size 0.4μ, manufactured by Soken Kagaku Co., Ltd.).
A coated carrier (b) was obtained in the same manner as above. (ii) Coating of inorganic particles The carrier (b) and inorganic particles (d) were coated for 10 minutes using a multi-blender mill (manufactured by Nippon Seiki Seisakusho Co., Ltd.).
．． The mixture was mixed for 5 minutes at 00 rpm, and then inserted into an autoclave TAS-1 (manufactured by Pressure Glass Industry Co., Ltd.) equipped with a stirrer. This was stirred for 3 hours (700 rpm) at a temperature of 200°C under nitrogen pressure (30 kg/cm'), and the resulting particles were sieved (sieve opening = 105 μml) to remove aggregates and carrier Obtained. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 4 Carrier (2) was obtained in the same manner as in Example 3 using the materials shown in Table 2. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 5 Ferrite carrier F-250I (R (average particle size 50μ
By the same method as in Example 3 using 1000 parts by weight of epoxy resin EP-13 (particle size 2 to 10μ, manufactured by Toshiku Co., Ltd.) and inorganic particles (f). , got a career ■. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 6 Ferrite carrier X-012 (average particle size 50 μm, manufactured by Fuji Electrochemical Co., Ltd.) 1000 parts by weight, polystyrene N
Carrier (2) was obtained in the same manner as in Example 3 using 30 parts by weight of PP-82460(A)-03 (average particle size: 3 μR1, manufactured by Japan Synthetic Rubber Co., Ltd.) and inorganic particles (b). Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 7 Ferrite carrier FMC-6 (manufactured by TDK Corporation) was coated with fluorine acrylic resin Modeiper F210 (average particle size 50μ dust, electrical resistance 6.7x 1)
Carrier ① was obtained in the same manner as in Example 3 using 0'1 Ωam) and inorganic particles (c). Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 8 Polyester resin Tufton NEIIIO (Kao Corporation)
Ferrite carrier F-25 was used as a carrier core material after uniformly dispersing the ferrite carrier
0HR (average particle size 50μl, electrical resistance 3.50xlO'
ΩCl11, manufactured by Nippon Iron Powder Co., Ltd.) was added. This was spray-dried using a spray drying method, and the carrier surface was coated with polyester resin (average particle size: 53 μm).
11 electrical resistance 1.9 x 10" Ωcm) was obtained. Using the coated carrier and inorganic particles (a), a carrier (2) was obtained in the same manner as in Example 3. The physical properties of the carrier and the results of the printing durability test were The results are shown in Table 2. Example 9 A coated carrier (average particle size: 53μ , electrical resistance 7.86xlO”Ωcm
) was obtained. A carrier (2) was obtained in the same manner as in Example 3 using the coated carrier and inorganic particles (e). Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 1O A ferrite carrier coated with an acrylic resin F 1 41-3040 manufactured by Nippon Tetsuko Co., Ltd. Carrier
(Average particle size 50μ, electrical resistance 3.50×107Ωcm
, manufactured by Nippon Tetsuko Co., Ltd.) as carrier ■. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Comparative Example 2 F99- whose surface was coated with acrylic modified silicone resin
3040 (average particle size 52μ, electrical resistance 1.40X1
0"Qc+n, manufactured by Nippon Tetsuko Co., Ltd.) is used as Carrier ■. The physical properties of the carrier and the results of the printing durability test are shown in Table 2. Comparative Example 3 Polyester resin Tufton NEIIIO (Kao Corporation)
Ferrite carrier F-25 was used as a carrier core material after uniformly dispersing the ferrite carrier
0HR (average particle size 50μ, electrical resistance 3.50X10'
Ωcan, manufactured by Nippon Tetsuko Co., Ltd.) was added. This was spray-dried using a spray-drying method to obtain coated carrier XII [(average particle size 53 μl, electrical resistance 1.9×10”ΩCff1) whose carrier surface was coated with polyester resin. Physical properties and printing durability test of the carrier The results are shown in Table 2. Comparative Example 4 100 parts by weight of ferrite MFP-2 (manufactured by TDK Corporation) and bisphenol type polyester resin (softening point 1
23℃, glass transition point 65℃, AV; 21, OHV,
43, Mn: 7,600, Mw: 188°4
00) 40 parts were uniformly dispersed in a toluene solvent by high shear stirring. Add to this the above iron powder + IJ as a core material.
7TEFV250/400 (average particle size 50 μy 1 true Kita weight 7.6, manufactured by Nippon Tetsuko Co., Ltd.) was added, spray-dried using the spray dry method, and the carrier surface was coated with polyester resin to form carrier XIV. Obtained. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Comparative Example 5 Iron powder carrier TEFV250/40 without coating
0 (manufactured by Nippon Iron Powder (Madhi)) was used as Carrier X■. Table 2 shows the physical properties of the carrier and the results of the printing durability test. Example 11 Bisphenol type polyester resin (softening point 123°C,
A toluene solution (glass transition point: 65°C, A-V: 21) (
2%) was adjusted. Next, the core material ferrite F-250H
R (average particle size 50μ, electrical resistance 3.50X107ΩO
R, manufactured by Nippon Steel Powder Co., Ltd.) was sprayed at a pressure of 3 using Subira Coater 5P-40 (manufactured by Kaida Seiko Co., Ltd.).
, 5 kg7cm”, spray amount 401F/min,
The treatment was carried out at a temperature of 50°C for 120 minutes. A coated carrier (A) was obtained by removing aggregates from the obtained particles using a sieve (sieve opening = 105 μII). 400 parts by weight of the coat carrier (A) and Fe-Zn ferrite fine particles MP'P-2 (5,21X1011Ω
・Cj! 4 parts by weight of T-D-K Co., Ltd.) was added to Ongmill A.
M-20F" (manufactured by Hosokawa Micron Co., Ltd.) at a rotation speed of 1000 rprA for 40 minutes. Aggregates were removed from the obtained carrier particles using a sieve (sieve opening: 105 μR) to obtain carrier (i). The physical properties of the carrier and the results of the printing durability test are shown in Table 3. Example 12 Bisphenol type polyester resin (softening point 13 picoC,
(glass transition point: 68° C., A-V: 28) was finely pulverized using a jet pulverizer to obtain resin particles with a particle size of 3.4 μm. Next, 400 parts by weight of the core material ferrite of Example 11 and 40 parts by weight of fine particles of polyester resin were mixed into Ongmill AM-20F (
Using Hosokawa Micron Co., Ltd.), the rotation speed was 150O.
Processed for 45 minutes at rpm. The obtained particles are sieved (
Aggregates were removed using a sieve with a diameter of 105 μm to obtain a coated carrier (B). 350 parts by weight of the coat carrier (B) and Fa-Mg ferrite fine particles X-703 (4.28 x 107 Ω·c
x, pH 7, manufactured by Fuji Electrochemical Co., Ltd.) was treated in the same manner as in Example 11. The obtained carrier (ii
Table 3 shows the physical properties and printing durability test results of ). Example 13 The polyester resin of Example 11 was replaced with styrene-Agril copolymer resin Hymer SBM-73F (manufactured by Kochu Kasei Kogyo Co., Ltd.), and toluene/methyl ethyl ketone = 70
A coated carrier (C) was obtained in the same manner as in Example 11 using the core material ferrite of Example 11 by adjusting the concentration to 3% with a mixed solution of /30. Next, 350 parts by weight of the coat carrier (C) and acidic magnetite fine particles RB-BL (2°15X1
0"9cmSpH4, 7 parts by weight of Titanium Kogyo Co., Ltd. was treated in the same manner as in Example 11. The physical properties of the obtained carrier (iii) and the results of the printing durability test are shown in Table 3. Examples 14 Using 400 parts by weight of the core material ferrite of Example 11, polymethyl methacrylate resin MP-1000 (particle size 0.4μ1) was used instead of the polyester resin fine particles of Example 12.
1 (glass transition point: 120° C.) and treated with Ongmill AM-20F (manufactured by Hosokawa Micron Co., Ltd.) at a rotational speed of 170 rpm for 60 minutes. A coated carrier (D) was obtained by removing aggregates from the obtained particles using a sieve (sieve opening: 105 μjI). Next, 500 parts by weight of the coat carrier (D) and acidic magnetite fine particles RB-BL (2,15X10'
25 parts by weight of Ω·Cx, pi-(4, manufactured by Titanium Kogyo Co., Ltd.) were mixed for 10 minutes at 110,000 rpm using a multi-breeder mill (manufactured by Nippon Seiki Seisakusho Co., Ltd.). Then, the number of revolutions was 4 in a rotary electric furnace (manufactured by Toho Electric Co., Ltd.).
The carrier particles were treated at 120° C. for 2 hours and aggregates were removed using a sieve (sieve opening = 105 μm) to obtain carrier (iv). Table 3 shows the physical properties of the carrier and the results of the printing durability test. Example 15 350 parts by weight of the coat carrier (A) of Example 11 and magnetite fine particles EPT-1000 (5,35X10'Ω
cx, manufactured by Toda Kogyo Co., Ltd.) 3.5 parts by weight was added to Ongmill A.
The treatment was carried out using M-20F (manufactured by Hosokawa Micron Co., Ltd.) at a rotational speed of 100 rpm for 40 minutes. Aggregates were removed from the obtained carrier particles using a sieve (sieve opening: 105 μm) to obtain a carrier (v). Table 3 shows the physical properties of the carrier and the results of the printing durability test. Example 16 Core coated carrier F99-3040 (average particle size 50
μ shoulder, electrical resistance value 3.91
(2,15x 101IQcrt, pH 4, manufactured by Titanium Kogyo Co., Ltd.) 14 parts by weight was treated in the same manner as in Example 6. Table 3 shows the physical properties of the obtained carrier (vi) and the results of the printing durability test. Comparative Example 6 Uncoated carrier F-250HR (average particle size 50μ1
1 electrical resistance 3.50xlO7Ωam, manufactured by Nippon Tetsuko Co., Ltd. (carrier vi). The physical properties and the results of the printing durability test are shown in Table 3. Comparative Example 7 A carrier (A) obtained by coating the ferrite carrier F-250HR of Example II with a polyester resin was used (
Career vi). Table 3 shows the physical properties and printing durability test results. Comparative Example 8 Styrene-acrylic copolymer resin Hymer S of Example 13
BM-73F' coated ferrite carrier (C) was used (carrier ix). Table 3 shows the physical properties and printing durability test results. Comparative Example 9 400 parts by weight of the coat carrier (a) of Example 11 and acidic magnetite fine particles RB-BL (2,15×10 8 Ω
cIII, pH 4, manufactured by Titanium Kogyo Co., Ltd. (12 parts by weight) was treated in the same manner as in Example 5. Career obtained (
Table 3 shows the physical properties and printing durability of X). Effect of Moxibustion The carrier of the present invention has polymers and inorganic fine particles with different charging polarities exposed on the carrier surface, and has high electrical resistance and moderate conductivity in parts, so the charge builds up quickly. Moreover, it has stable triboelectric charging properties, does not accumulate charge even after long-term use, and can provide a stable amount of charge to the toner, eliminating the carrier phenomenon. Furthermore, the carrier of the present invention has excellent durability and moisture resistance because no solvent remains in the coating layer and no pores are formed due to evaporation of the solvent. Patent applicant: Minolta Camera Co., Ltd.

Claims (2)

[Claims] (1) A method for producing a carrier for developing electrostatic latent images, which comprises coating carrier core particles with a resin, and fixing inorganic fine particles having opposite charge polarity to the surface of the coating layer. (2) A carrier for developing an electrostatic latent image obtained by coating carrier core particles with a resin and fixing inorganic fine particles having opposite charging polarity to the surface of the coating layer.