JPH0557585B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrostatic image developer used for developing an electrostatic latent image formed in electrophotography, electrostatic recording, electrostatic printing, etc., and this electrostatic image developer. Electrostatic image developing method for developing an electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor using an image developer, and these electrostatic image developers and electrostatic image developing method The present invention relates to an image forming method for forming an image using an electrostatic image developer and an electrostatic image developer suitable for developing a negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor. The present invention relates to an electrostatic image developing method and an image forming method. [Background of the Invention] Generally, in electrophotography, a photoreceptor having a photosensitive layer made of a photoconductive material is given a uniform electrostatic charge, and then image exposure is performed to create an electrostatic latent on the surface of the photoreceptor. An image is formed, and this electrostatic latent image is developed with a developer to form a toner image. After the obtained toner image is transferred to a transfer material such as paper,
A copy image is formed by fixing by heating or pressure. Examples of the photoconductive material used to form the photosensitive layer of the photoreceptor include inorganic photoconductive materials such as selenium, zinc oxide, and cadmium sulfide, and organic photoconductive materials made of high molecular compounds or low molecular weight compounds such as polyvinyl carbazole. There are known materials such as carbonaceous materials.
However, although photoreceptors having photosensitive layers formed from these photoconductive materials have one advantage in forming electrostatic latent images, they also have drawbacks specific to various photoreceptors. have. For example, in a photoreceptor having a photosensitive layer formed of selenium, the photosensitive layer easily crystallizes due to heat or metal compounds contained in the developer or transfer material, deteriorating its properties, resulting in an electrostatic latent image. There is a problem that the potential of the image decreases, resulting in a decrease in image density or partial image blanking. In addition, under high humidity environmental conditions, the photoconductivity of the photosensitive layer decreases and static charges remain in the non-image areas of the photoreceptor, resulting in fogging and making it difficult to obtain clear images. First, under high humidity environmental conditions, good images cannot be formed many times and durability is low. Additionally, photoreceptors having a photosensitive layer formed of cadmium sulfide or a photoreceptor having a photosensitive layer formed of zinc oxide typically have a photoconductive material, ie, cadmium sulfide or zinc oxide, dispersed in a binder resin. A photosensitive layer is formed, but it is quite difficult to uniformly disperse such a photoconductive material in the form of fine particles in a binder resin, and as a result, the resulting photoreceptor has low sensitivity and is unsuitable for high-speed copying. In addition, the photosensitive layer tends to deteriorate early in the corona charging process or exposure process that is normally used to form an electrostatic latent image, and therefore it is difficult to maintain a good image quality over a long period of time. Furthermore, under high-humidity environmental conditions, the characteristics of the photosensitive layer change due to moisture, making it impossible to obtain the desired electrostatic latent image potential, resulting in low image density. There is a problem. On the other hand, organic photoreceptors having a photosensitive layer formed from a polymeric photoconductive material typified by polyvinylcarbazole have good film-forming properties and can be manufactured at low cost. It has been attracting attention in recent years due to its advantages such as non-toxicity, but on the other hand, it has low sensitivity and is prone to early deterioration during the corona charging process or exposure process, resulting in poor durability. Since the sensitivity or charge retention ability tends to change, it is still inferior to a photoreceptor having a photosensitive layer made of an inorganic photoconductive material, and the development of a high-performance photoconductive material is desired. On the other hand, in order to overcome the above problems, in recent years,
It has been proposed to use low molecular weight organic photoconductive materials. Since low molecular weight organic photoconductive materials generally have good dispersibility in binder resins, the resulting photosensitive layer has the organic photoconductive materials uniformly dispersed in the form of fine particles, resulting in a high sensitivity. A relatively high photoreceptor can be obtained, and by forming the photosensitive layer by dispersing an organic photoconductive material in a binder resin,
Film-forming properties are improved, and photoreceptors can therefore be manufactured with high productivity.In addition, there are many types of low-molecular-weight photoconductive materials that can be used, and therefore, it is possible to use appropriately selected low-molecular-weight photoconductive materials. By using the photoreceptor, it is possible to obtain a photoreceptor having better performance than conventional ones. Thus, an organic photoreceptor having a photosensitive layer formed of a low molecular weight organic photoconductive material is more preferable than conventional photoreceptors. However, since organic photoconductive materials usually exhibit photoconductivity through the movement of positive charges, it is difficult to form photoconductive materials on the surface of an organic photoreceptor that has a photosensitive layer formed from the organic photoconductive material. The polarity of the electrostatic latent image is preferably negative. In order to develop a negative electrostatic latent image, it is necessary to use a developer containing positively charged toner. However, in the conventionally widely used photoreceptor having a photosensitive layer made of selenium, etc., the polarity of the electrostatic latent image formed on the surface is positive, so it is difficult to develop the electrostatic latent image. Developers containing negatively charged toner are used, and considerable research and development efforts have been made on developing agents containing negatively charged toner. Research and development of developers containing toner is still lagging behind, and the reality is that a developer containing a sufficiently positively charged toner has not been obtained. On the other hand, wet developing methods and dry developing methods are known as methods for developing electrostatic latent images. The former wet development method uses a liquid developer, which has the problem of emitting a bad odor, and also requires high energy to dry the transfer material, making high-speed copying difficult. The latter dry developing method does not have such problems and can be preferably used as a developing method for electrostatic latent images. The developer used in the dry development method is a so-called one-component developer consisting only of a magnetic toner containing a magnetic substance, and a so-called two-component developer consisting of a non-magnetic toner that does not contain a magnetic substance and a magnetic carrier. type developer is known. The former one-component developer consists only of magnetic toner and does not have a carrier, so there is some frictional electrification caused by the toners and the height of the toner and the developing sleeve or developer layer placed in the developing device is controlled. The toner is charged by frictional charging with the regulation blade, etc., and as a result, both positively charged toner and negatively charged toner exist.
Moreover, since the amount of triboelectric charge is small, there is basically a problem that development tends to be unstable. Specifically, for example, toner may adhere to non-image areas on the photoreceptor, causing fog on the final fixed image, or
Alternatively, there is a problem that an insufficient amount of toner adheres to the image area on the photoreceptor, resulting in a low density of the final fixed image. In addition, the magnetic material used in magnetic toner usually has hydrophilic properties, and since this hydrophilic magnetic material is often contained in an exposed state on the surface of toner particles, the toner becomes triboelectrically charged due to moisture. Charge tends to leak, and in a high-humidity atmosphere, the electrostatic transfer to the transfer paper normally used as a transfer material becomes defective during the transfer process, resulting in a low toner transfer rate to the transfer paper. As a result, there are problems in that the density of the final fixed image decreases and image blanking occurs. In addition, since the magnetic material used in magnetic toner usually has negative chargeability, it is difficult to positively charge the magnetic toner with an appropriate amount of charge.
Therefore, there is a large proportion of toner of opposite polarity, which results in a lower density in the final fixed image, and also causes problems such as unevenness and missing images. On the other hand, the latter two-component developer is composed of toner and a carrier, and the carrier has the function of charging the toner to a desired polarity, so it is possible to charge the toner with an appropriate polarity and an appropriate charge. It is possible to impart a triboelectric charge depending on the amount, and it is possible to obtain a developer having much superior triboelectric chargeability compared to the one-component developer described above. Also,
By selecting a carrier having desired characteristics, it is possible to control the amount of charge on the toner to a considerable extent. However, in order to obtain a good final fixed image, it is not enough that the developer has good triboelectric chargeability, and particles of the developer to which triboelectric charge has been applied do not aggregate in the developing device. It is necessary that the film be transported to the developing space in good condition without any damage. For example, in the magnetic brush development method, a developer that has been given a triboelectric charge by being stirred in a developing device is supported on the developing sleeve in the form of a thin layer arranged in a uniform brush shape. It is necessary for the developer layer having the same shape to be stably transported to the development space while retaining its shape. For example, in a one-component developer, since it consists only of magnetic toner and does not have a carrier, the magnetic toner has strong magnetic cohesive force and electrostatic cohesive force. There is a problem in that the fluidity of the developer is reduced, and as a result, it is difficult to carry the magnetic toner on the developing sleeve in the form of a thin layer arranged in a uniform brush shape. In addition, since the magnetic toner tends to form agglomerates, frictional electrification between the magnetic toners or between the magnetic toner and the wall, regulating blade, developing sleeve, etc. inside the developing device is not achieved properly. As a result, there is a problem that the final fixed image becomes unclear with a lot of fog. Furthermore, for example, in a two-component developer, if the toner tends to aggregate and form clumps due to electrostatic cohesive force, it becomes difficult to disperse the toner particles in the carrier particles at a uniform concentration.
As a result, the triboelectricity between the toner and the carrier decreases, and the proportion of toner with low triboelectricity increases.In the developing process, toner adheres to non-image areas on the photoreceptor, causing fog in the final fixed image. death,
In addition, there is a large amount of weakly charged toner, and the electrostatic adhesion between the toner and the carrier is small. Therefore, in the magnetic brush development method, the toner particles attached to the carrier particles are rotated by the magnetic force. When conveyed to the developing space, the toner particles scatter due to the centrifugal force caused by the rotation of the carrier particles, and as a result, they contaminate various devices such as the charger and exposure optical system installed in the copying machine, and the final fixation is interrupted. There is a problem that image defects such as image unevenness and image blanking occur in the image. However, in conventional negatively charged toners, fine silica particles having a smaller diameter than the toner particles are mixed with the toner particles to attach the fine silica particles to the surface of the toner particles, thereby preventing the toner from clumping. This is done to obtain high liquidity. However, conventionally used silica fine particles have strong negative chargeability, so when obtaining a positively chargeable toner, if silica fine particles are mixed with the toner and attached to the surface of the toner particles, the resulting toner will be negatively charged. There is a problem in that it becomes chargeable, and as a result, becomes the same polarity as the negative electrostatic latent image formed on the photoreceptor, making it impossible to carry out electrostatic development. The following technologies have been developed to solve these problems. (1) Technology using positively charged fine particles treated with a silane coupling agent (see JP-A-53-66235, JP-A-56-123550, and JP-B-Sho 53-22447). (2) Technology using positively charged fine particles treated with silicone oil (Japanese Unexamined Patent Publication No. 1983-60754,
(See Publication No. 59-187359). [Problems to be Solved by the Invention] However, as in techniques (1) and (2) above, positively charged fine particles treated with a silane coupling agent or silicone oil are used and mixed with the toner. Even if they are attached to the surface of the toner particles, when subjected to physical force such as stirring in the developing device, the fine particles will scatter from the surface of the toner particles, and as a result, the toner will not have an appropriate amount of charge. The fine particles that are not positively triboelectrically charged and scattered become attached physically or electrostatically to the inner wall of the developing device, the developing sleeve disposed inside the developing device, the regulating blade, the carrier particle surface, etc., and the toner If the triboelectricity is inhibited and the accumulation due to adhesion of fine particles becomes excessive, the fine particles and toner particles will be triboelectrically charged, and the toner particles will be charged with opposite polarity, that is, negatively charged, and as a result, the toner will scatter. There are problems in that the inside of the apparatus becomes contaminated, and in the final fixed image, fogging occurs and the image density decreases, resulting in an unclear image. Further, when image formation is repeated many times, the image gradually becomes less clear, resulting in a defective image at an early stage, resulting in low durability. In particular, when using fine particles treated with a silane coupling agent, it is difficult to completely cover the surface of the fine particles with the silane coupling agent, and as a result, negatively charged sites and hydrophilic sites of the fine particles remain. , the positive chargeability of the toner decreases due to the remaining amount of negatively chargeable sites, and furthermore, the toner becomes negatively chargeable, causing a lot of fogging in the final fixed image. As a result, it becomes susceptible to the effects of humidity, and as a result, when environmental conditions change, the triboelectric charging ability becomes unstable, resulting in the inside of the device being contaminated by toner scattering, and fogging occurring in the final fixed image. Further, there are problems in that the image density decreases due to a decrease in the transfer rate in the transfer process, and image unevenness occurs due to toner scattering, resulting in an unclear image. In addition, especially when using fine particles treated with silicone oil, the surface of the fine particles is covered with a sticky oily substance, so such fine particles are mixed with the toner to coat the surface of the toner particles. It is difficult to improve the fluidity of the toner even if it is attached to the toner, physical aggregation may occur due to silicone oil, and fine particles may adhere to the inner wall of the developing device, the developing sleeve, the regulating blade, etc. to reduce the positive chargeability of the toner,
As a result, there is a problem in that the developability is lowered, contamination occurs due to toner scattering, and the final fixed image becomes unclear with a lot of fog and image gaps. In addition, in the image forming process, the toner image formed on the surface of the photoreceptor through the development process is subjected to a transfer process, and in this transfer process, it is transferred to a transfer material made of ordinary paper or the like. As the transfer means, it is preferable to use electrostatic transfer means that utilizes electrostatic force. However, as in the techniques (1) and (2) above, the toner formed on the surface of the photoreceptor is developed with a toner composed of fine particles treated with a silane coupling agent or silicone oil. It is difficult to transfer images well using electrostatic transfer means due to insufficient charge and strong adhesion to the surface of the photoreceptor.
As a result, there are problems in that image unevenness and image missing occur in the final fixed image, and image density decreases. Further, the photoconductor after the toner image has been transferred in the transfer process is then subjected to a cleaning process, and in this cleaning process, the toner remaining on the surface of the photoconductor after the transfer process is removed, and the surface of the photoconductor is cleaned. Cleaned. However, as in the techniques (1) and (2) above, toners constructed using fine particles treated with a silane coupling agent or silicone oil,
Due to the strong physical and electrostatic adhesion force to the surface of the photoconductor, it is difficult to completely clean the residual toner, and as a result, some toner remains on the photoconductor and is not used for the next image formation. have a negative impact,
There is a problem that the image becomes unclear. Further, the transfer material onto which the toner image has been transferred in the transfer step is subjected to a fixing step, and the toner image is heated or pressurized by a heat roller to be fixed to the transfer material, thereby forming a final fixed image. However, as in the techniques (1) and (2) above, toner composed of fine particles treated with a silane coupling agent or silicone oil tends to transfer and adhere to the surface of the heated roller. As a result, the so-called offset phenomenon occurs, in which the toner that has adhered to the heat roller is transferred again to the transfer material that is sent next, staining the image.Also, when the toner that has adhered to the heat roller solidifies, this causes the heat roller to become stained. There is a problem that the surface is damaged and the durability of the heat roller is significantly reduced. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its objects are (1) to provide an electrostatic image developer having good positive chargeability and excellent moisture resistance; (2) To provide an electrostatic image developing method capable of satisfactorily developing a negative electrostatic latent image formed on an organic photoconductive photoreceptor without scattering of developer particles; (3) To provide an image forming method that can stably form images of high image density, fog-free, and good image quality many times without being affected by environmental conditions. [Means for Solving the Problems] The electrostatic image developer of the present invention has its surface treated with a silane coupling agent having an epoxy group, and further contains an amino compound represented by the following general formula (1). Consisting of silica fine particles treated with 1
0.1 to 5% by weight of inorganic fine particles (hereinafter also referred to as "specific inorganic fine particles") having an average particle size of 5 to 500 mμ and a specific surface area of 20 to 500 m ² /g by BET method are mixed into the toner. It is characterized by: General formula (1) (R ¹ , R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 9 or less carbon atoms, n
represents an integer from 1 to 4. ) The electrostatic image developer of the present invention is a photoreceptor (hereinafter also referred to as "organic photoreceptor") made of an organic photoconductive semiconductor.
The negative electrostatic latent image formed on the surface of the image forming apparatus is characterized in that the negative electrostatic latent image formed on the surface of the image forming apparatus is developed using an electrostatic image developer mixed with the specific inorganic fine particles. The image forming method of the present invention includes a latent image forming step of forming a negative electrostatic latent image on the surface of the organic photoreceptor, and an electrostatic image development step in which the electrostatic latent image is mixed with the specific inorganic fine particles. a development step in which the toner image obtained by development is electrostatically transferred to a transfer material; and a cleaning step in which the developer remaining on the surface of the organic photoreceptor is cleaned with a cleaning blade after the transfer step. and a fixing step of heating and fixing the toner image on the transfer material using a heat roller fixing device having a heat roller coated with a fluorocarbon resin or a silicone resin. . [Operations and Effects of the Invention] Since the electrostatic image developer of the present invention contains specific inorganic fine particles, it has good positive chargeability and excellent moisture resistance. That is, by treating the surface of inorganic fine particles with a silane coupling agent having an epoxy group,
The silane coupling agent having an epoxy group binds to the hydrophilic site and the negatively charged site on the surface of the inorganic fine particles and is firmly held on the surface, resulting in a silane coupling agent having an epoxy group. This imparts hydrophobicity to the inorganic fine particles, and by further treating the surface of the inorganic fine particles with a specific amino compound, the inorganic fine particles are given positive chargeability, and as a result, even under high humidity environmental conditions, the inorganic fine particles become hydrophobic. Positive chargeability by the fine particles is stably exhibited, and a developer with excellent positive chargeability can be obtained. In addition, the specific inorganic fine particles mentioned above have good adhesion to the developer and are firmly held by the developer particles, so that when the developer is stirred in the developing device, This prevents inorganic fine particles from transferring and adhering to the inner wall of the developing device, the developing sleeve, the regulating blade, etc., and as a result, the developer exhibits stable positive chargeability even when the image forming process is performed multiple times. Become. Since the specific inorganic fine particles impart high fluidity to the developer, the developer particles do not aggregate and are triboelectrically charged in a stable state. According to the electrostatic image developing method of the present invention, an electrostatic image developer containing the above-mentioned specific inorganic fine particles can be used to
Since the negative electrostatic latent image formed on the surface of the photoreceptor made of an organic photoconductive semiconductor is developed, the organic photoreceptor can be easily processed without sacrificing the advantages of organic photoreceptors such as low production cost and non-toxicity. A negative electrostatic latent image formed on the image can be developed satisfactorily without scattering of developer particles. In other words, since the above-mentioned developer has excellent positive chargeability, it becomes positively charged with an appropriate amount of charge, and therefore, the developer particles are stably held in the development sleeve and enter the development space. This makes it possible to prevent contamination caused by scattering of developer particles.
In addition, as mentioned above, the fluidity of the developer is excellent, so it is possible to form a magnetic brush of uniform and uniform developer on the developing sleeve, and therefore good development can be achieved using the magnetic brush development method. It becomes possible to do so. According to the image forming method of the present invention, since the electrostatic image developer is a mixture of the above-mentioned specific inorganic fine particles and has excellent positive chargeability, the non-image on the organic photoreceptor is As a result, it is possible to obtain a clear final fixed image without fogging. In addition, since the specific inorganic fine particles give the developer suitable releasability, the physical adhesion to the surface of the organic photoreceptor is small. Transfer can be performed, and it is possible to form a clear image with high image density and no image unevenness. In addition, as described above, the transferability of the developer is good, so only a small amount of developer remains on the organic photoreceptor after the transfer process, making it easy to clean the remaining developer in the cleaning process. Moreover, as mentioned above, the developer has good mold releasability, so the adhesion of the developer to the organic photoreceptor is small, and as a result, the developer can be easily cleaned using a cleaning blade. becomes possible. Furthermore, since the cleaning properties of the developer are good, good cleaning can be achieved with a small pressure contact force of the cleaning blade against the organic photoreceptor. This prevents the characteristics of the organic photoreceptor from prematurely deteriorating due to surface friction, and the service life of the organic photoreceptor can be significantly extended. In addition, in the fixing process, the specific inorganic fine particles are present between the surface of the molten developer and the heat roller, so that a mold release effect is obtained by the specific inorganic fine particles, and the developer is transferred to the heat roller. It also prevents developer from accumulating in the minute grooves of the heat roller.
Since the heat roller is coated with a fluorine-based resin or a silicone-based resin, transfer and adhesion of the developer to the heat roller is further prevented, and as a result, image staining caused by the offset phenomenon can be prevented. Furthermore, since the surface of the specific inorganic fine particles is covered with a silane coupling agent having an epoxy group and further covered with a specific amino compound, there is less risk of the surface of the heat roller being damaged by the specific inorganic fine particles. , it becomes possible to significantly extend the service life of the heat roller, and excellent offset resistance can be stably obtained over a long period of time. [Specific constitution of the invention] The electrostatic image developer of the present invention has a surface treated with a silane coupling agent having an epoxy group, and is further mixed with inorganic fine particles treated with a specific amino compound. . Specifically, the following compounds can be used as the epoxy group-containing silane coupling agent. Exemplary compounds (1) ("SH6040", manufactured by Toray Silicone) Exemplary compounds (2) Exemplary compounds (3) Exemplary compounds (4) (“KBM463”, manufactured by Shin-Etsu Silicone Co., Ltd.) The specific amino compound has the general formula (1) (R ¹ , R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 9 or less carbon atoms, n
represents an integer from 1 to 4. ), such as diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, hexamethylenediamine, trimethylhexamethylenediamine, bis-( (hexamethylene)triamine, etc. can be used. In the present invention, the surface of inorganic fine particles is first treated with a silane coupling agent having an epoxy group, and then the surface treated with the silane coupling agent having an epoxy group is further treated with a specific amino compound. By treating the surface of the inorganic fine particles in this order, the treated inorganic fine particles have good hydrophobicity and good positive chargeability. In other words, by first treating the surface of the inorganic fine particles with a silane coupling agent having an epoxy group, the silane coupling agent having an epoxy group binds to the hydrophilic site or negatively charged site of the inorganic fine particle, and this becomes strong. As a result, the epoxy group-containing silane coupling agent imparts hydrophobicity to the inorganic fine particles, and by further treating the hydrophobically imparted surface with a specific amino compound, the inorganic particles become The amino compound is surely present in the outermost layer of the fine particles, and since the amino compound is reactive with the silane coupling agent having an epoxy group, the amino compound is firmly retained. As a result, the amino compound imparts positive chargeability to the inorganic fine particles, resulting in the inorganic fine particles having excellent impact strength, moisture resistance, mold releasability, and positive chargeability. Silica fine particles are used as the inorganic fine particles whose surfaces are treated with the epoxy group-containing silane coupling agent and further with a specific amino compound. The inorganic fine particles have an average particle size of primary particles (particles separated into individual unit particles) within a range of 5 mμ to 500 mμ. Silica fine particles are fine particles having Si-O-Si bonds, and may be manufactured by either a dry method or a wet method, but those manufactured by a dry method are preferable, and in particular, silicon halogen compounds. Preferably, the silica particles are silica particles produced by vapor phase oxidation. In addition, as fine silica particles,
In addition to silicon dioxide (silica), fine particles may be made of silicates such as aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate, and magnesium silicate.
Those containing 85% by weight or more of SiO ₂ are preferred. As a method for treating the surface of the inorganic fine particles with a silane coupling agent having an epoxy group and further with a specific amino compound, known techniques can be used and there are no particular limitations. Specifically, it can be processed as follows. (1) A method in which inorganic fine particles are dispersed in a solution of a silane coupling agent having an epoxy group dissolved in a solvent, the solvent is removed by filtration or spray drying, and then the method is cured by heating, or a fluidized bed is used. The surface of the inorganic fine particles is coated using a method such as spray coating a solution of a compound having an epoxy group in a solvent on the inorganic fine particles using a device, and then heating and drying to remove the solvent and harden the film. is treated with a silane coupling agent having epoxy groups. (2) Next, in the same manner as above, the surface of the inorganic fine particles treated with the epoxy group-containing silane coupling agent is further treated with a specific amino compound. The particle size of the inorganic fine particles obtained in this manner, the surface of which has been treated with a silane coupling agent having an epoxy group and then with an amino compound, is 1.
The average particle size of the secondary particles is within the range of 5 mμ to 500 mμ. In addition, the specific surface area by BET method is 20
~500m ² /g. If the average particle diameter is too small or the specific surface area is too large, the inorganic particles may easily slip through during cleaning using, for example, a blade-type cleaning device, resulting in poor cleaning. On the other hand, when the average particle diameter is too large or the specific surface area is too small, the fluidity of the developer decreases, resulting in poor developability, which may result in a decrease in image density or the occurrence of image unevenness. When constituting a one-component developer, the specific inorganic fine particles are added to and mixed with the magnetic toner particles from the outside, and are contained in a state where they are attached or implanted onto the surface of the magnetic toner particles. . In addition, when forming a two-component developer, the specific inorganic fine particles are added to and mixed with the non-magnetic toner particles from the outside, so that they are attached or implanted onto the surface of the non-magnetic toner particles. A carrier is further mixed into this. The mixing ratio of the specific inorganic fine particles is determined based on the toner.
The content is 0.1 to 5% by weight, preferably 0.1 to 2% by weight. When the mixing ratio of the specific inorganic fine particles is too small, the fluidity of the developer may decrease, and as a result, the triboelectric charging properties of the toner become poor, and an appropriate amount of positive charge is applied to the toner. This may result in fogging or image unevenness. Furthermore, when the mixing ratio is too large, some of the specific inorganic fine particles may exist in a free state from the toner particles, and as a result, the free specific inorganic fine particles may adhere to and transfer to the carrier particles, or It adheres and accumulates on the inner wall of the developing device, the developing sleeve, the regulating blade, etc., and eventually the triboelectric charging properties of the toner become poor, making it difficult to apply an appropriate amount of positive charge to the toner, resulting in fogging and image formation. A decrease in concentration may occur. The electrostatic image developer of the present invention may basically be a one-component developer consisting only of magnetic toner, or a two-component developer consisting of a non-magnetic toner and a magnetic carrier. It's okay, but
In particular, a two-component developer is preferred. The non-magnetic toner is a particle powder containing a colorant and other additives in a binder, and the magnetic toner is a particle powder containing a colorant, a magnetic substance, and other additives in a binder. It is a particulate powder made up of The average particle size of the toner is usually preferably about 5 to 20 μm.
Other additives include, for example, a fixability improver,
A charge control agent, a cleaning property improving agent, etc. can be used. The binder for the toner is not particularly limited, and resins conventionally used for this type of use can be used. Specifically, for example, polystyrene resins, copolymers obtained from at least two or more monomers selected from styrene monomers, acrylic ester monomers, and methacrylic ester monomers, polystyrene-butadiene Resin, polyester resin, epoxy resin, polyamide resin, polyurethane resin, etc. can be used. Among these, at least two or more monomers selected from polystyrene resins, styrene monomers, acrylic ester monomers, and methacrylic ester monomers are preferred as those that do not inhibit the positive chargeability of the toner. The resulting copolymer can be preferably used. Examples of coloring agents include carbon black, phthalocyanine blue, benzine yellow, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, malachite green oxalate, and lamp black. , rose bengal, and other dyes and pigments can be used. These substances may be used alone or in combination, and the content of the colorant is usually preferably 1 to 15% by weight of the toner. Examples of fixability improvers include polyolefins, fatty acid metal salts, fatty acid esters and fatty acid ester waxes, higher fatty acids, higher alcohols, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, silicone varnishes, and aliphatic waxes. Fluorocarbon or the like can be used. As the charge control agent, for example, a metal complex dye or the like can be used. As the cleaning property improver, for example, fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer particles such as methyl methacrylate particles and styrene particles can be used. When the toner is a magnetic toner, a magnetic material is contained in the binder. This magnetic material is preferably contained in the binder in the form of a fine powder having an average particle size of 0.1 to 1 mμ, and is uniformly dispersed in the binder.
In addition, the content ratio of magnetic material is usually 100% of the toner.
It is preferably 10 to 70 parts by weight, particularly preferably 20 to 50 parts by weight. Such magnetic materials include iron, ferrite, magnetite, and other ferromagnetic metals or alloys such as cobalt and nickel, or compounds containing these elements, and materials that do not contain ferromagnetic elements but are subjected to appropriate heat treatment. As a result, alloys that exhibit ferromagnetism can be used, such as alloys called Heusler alloys containing manganese and copper such as manganese-copper-aluminum, manganese-copper-tin, chromium dioxide, and others. . When the electrostatic image developer of the present invention is a two-component developer, the carrier used in combination with the non-magnetic toner is not particularly limited. Specifically, carriers made of magnetic particles, resin-coated carriers made by coating the surface of magnetic particles with a specific resin, or magnetic fine particle dispersion made by dispersing fine magnetic particles in resin particles. A mold carrier or the like can be used. Examples of magnetic materials used in carriers include iron, ferrite, magnetite, and other magnetic materials.
A ferromagnetic metal or alloy such as cobalt or nickel, or a compound containing these elements can be used. The average particle size of the carrier is usually preferably about 10 to 500 μm, especially
It is preferably 20 to 200 μm. If the average particle size of the carrier is too small, an electrostatic latent image, that is, a phenomenon in which carrier particles adhere to the image area, may occur, resulting in a defective image.If the average particle size of the carrier is too large, the toner may be rubbed The surface area for charging becomes smaller, and as a result, the amount of poorly charged toner increases and image unevenness may occur. Next, the electrostatic image developing method of the present invention will be explained. In the electrostatic image developing method of the present invention, a negative electrostatic latent image formed on the surface of an organic photoreceptor is transferred to an electrostatic image developer (hereinafter referred to as "specific developer ) to form a toner image. The organic photoreceptor is usually constructed by laminating a photosensitive layer containing a photoconductive semiconductor made of an organic compound on a conductive support. The photosensitive layer is
The photoconductive semiconductor may be composed only of a photoconductive semiconductor made of an organic compound, or the photoconductive semiconductor may be dispersed and contained in a binder made of a resin. The photosensitive layer includes a carrier generation layer containing a carrier generation substance that absorbs visible light and generates charged carriers, and a carrier generation layer that transports either or both of positive and negative carriers generated in this carrier generation layer. and a carrier transport layer containing a carrier transport substance that
It is preferable to use a so-called functionally separated photosensitive layer. In this way, by assigning the two basic functions necessary for the photosensitive layer, namely carrier generation and carrier transport, to separate layers, the range of materials that can be used in the composition of the photosensitive layer is widened, and each It becomes possible to independently select a material or material system that performs the function optimally, and by doing so, it achieves the various properties required in the image forming process, such as high surface potential when charged and charge retention ability. It becomes possible to construct an organic photoreceptor having excellent properties such as being large, having high photosensitivity, and being highly stable in repeated use. Examples of carrier generating substances in the photosensitive layer include anthrone pigments, perylene derivatives,
Phthalocyanine pigments, azo dyes, indigoid dyes, etc. can be used. In addition, examples of carrier transport substances include carbazole derivatives,
Oxadiazole derivatives, triarylamine derivatives, polyarylalkane derivatives, hydrazone derivatives, pyrazoline derivatives, stilbene derivatives,
Styryl triarylamine derivatives and the like can be used. The thickness of the carrier generation layer is usually 0.01
The thickness of the carrier transport layer is preferably 1 to 30 μm. When forming a photosensitive layer by dispersing a photoconductive semiconductor made of an organic compound in a binder made of a resin, examples of the resin that can be used as the binder include polyethylene, polypropylene, acrylic resin, methacrylic resin, chloride resin, etc. Vinyl resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, addition polymerization type resin, polyaddition type resin, polycondensation type resin, and these Copolymer resins containing two or more of the repeating units of the resin, such as vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, styrene-acrylic copolymer resins, etc. Examples include insulating resins, and polymeric organic semiconductors such as poly-N-vinylcarbazole. In the organic photoreceptor, the conductive support is
For example, metal sheets made of aluminum, nickel, copper, zinc, palladium, silver, indium, tin, platinum, gold, stainless steel, steel, brass, etc. can be used. The specific structure of the organic photoreceptor is not particularly limited, and various structures can be adopted. Also, the surface potential when charged is, for example, -400 to -
An organic photoreceptor having a voltage of 1000V can be particularly preferably used. FIG. 1 is an explanatory diagram showing an example of a developing device that can be suitably used to carry out the electrostatic image developing method of the present invention. 10 is an organic photoreceptor, and this organic photoreceptor 10
has the shape of a rotating drum that rotates in the direction of arrow X, and is constructed by laminating a photosensitive layer 10B containing an organic photoconductive semiconductor on a cylindrical conductive support 10A made of aluminum, for example. ing. A charger and an exposure optical system (not shown) are arranged upstream of the development space 24. First, the charger sets the surface of the organic photoreceptor 10 to be developed at a voltage of, for example, -400 to -1000V.
The light image of the document is then projected onto the developed surface of the organic photoreceptor 10 by an exposure optical system (not shown), so that the developed surface corresponds to the document. An electrostatic latent image is formed, and the electrostatic latent image is moved to the development space 24, where the electrostatic latent image is developed. Reference numeral 11 denotes a developing sleeve. This developing sleeve 11 is made of a non-magnetic material such as aluminum and has a rotating drum shape, and a magnet body 12 is disposed inside this developing sleeve 11. This magnet body 12 consists of a plurality of N and S magnetic poles arranged along the circumference of the developing sleeve 11. These developing sleeve 11 and magnet body 12 constitute a developer transport carrier, and in one specific example,
The developing sleeve 11 is rotated to move, for example, in the direction of arrow Y, that is, in the same direction as the moving direction of the organic photoreceptor 10 in the developing space 24, and the magnet body 12 is fixed, for example. In the present invention, the rotation direction of the developing sleeve 11 is not particularly limited, and the magnet body 12 may be rotated in an appropriate direction. The N and S magnetic poles constituting the magnet body 12 are magnetized so that the magnetic flux density on the surface of the developing sleeve is usually about 500 to 1,500 Gauss, and the particles of the developer 22 are distributed on the surface of the developing sleeve 11 by the magnetic force. A developer layer (magnetic brush) 23 is formed in which the developer layer (magnetic brush) is made to stand up like a brush. Reference numeral 13 denotes a regulating blade, which is made of a magnetic or non-magnetic material and is used to regulate the height and amount of the developer layer 23 reaching the developing space 24. 14 is a cleaning blade, and this cleaning blade 14 is
This is for scraping and removing the developer remaining on the surface of the developing sleeve 11 after development. The surface of the developing sleeve 11 that has been cleaned by the cleaning blade 14 comes into contact with the developer 22 again in the developer reservoir 15, and a new magnetic brush is formed on the surface, and after this magnetic brush is regulated by the regulating blade 13, it enters the developing space. 24. 15 is a developer reservoir, and 16 is an agitating screw. In the developer reservoir 15, the toner and carrier constituting the developer 22 are mixed and dispersed by the agitating screw 16, thereby making the toner concentration uniform. . Furthermore, while the carrier of the developer 22 is used repeatedly, the toner is consumed every time development is performed, so the toner hopper 1
New toner No. 7 is appropriately replenished into the developer reservoir 15 by a supply roller 18 having a recessed portion on its surface. 19 is a bias power supply, 20 is a protection resistor,
A bias voltage necessary for development is applied to the developing sleeve 11 by the bias power supply 19 via the protective resistor 20. This bias voltage is, for example, 50~
A DC voltage of about 500V is preferable. In developing an electrostatic latent image, it is preferable that the tip of the magnetic brush make shallow contact with the surface of the organic photoreceptor 10 in order to achieve uniform development. The distance between them (Hcut) is preferably about 0.8 times the gap (Dsd) between the organic photoreceptor 10 and the developing sleeve 11 in the developing space 24. Further, it is preferable that the gap (Dsd) is, for example, 0.1 to 4.0 mm. When the gap (Dsd) is too small, the developability may deteriorate, while when the gap (Dsd) is too large, toner scattering tends to occur and the image may become unclear. In the apparatus configured as above, the developing sleeve 1
1 rotates, the magnitude and direction of the magnetic field on its surface sequentially change, so the carrier particles in the magnetic brush formed on the surface of the developing sleeve 11 are
The developing sleeve 11 is moved into the developing space 24 while rotating and vibrating, following the rotational movement of the developing sleeve 11.
As a result, the toner particles adhering to the surface of the carrier particles due to electrostatic force are transported to the developing space 24. Next, the image forming method of the present invention will be explained. In the image forming method of the present invention, a negative electrostatic latent image is formed on the surface of the organic photoreceptor (latent image forming step), and this electrostatic latent image is developed with the specific developer (developing step). , the toner image obtained by development is electrostatically transferred to a transfer material (transfer step), and the toner image on the transfer material is contact-heated with a heat roller coated with a fluorine-based resin or a silicone-based resin. The developer is fixed (fixing step) to form a fixed visible image, and the developer remaining on the surface of the organic photoreceptor after the transfer step is cleaned with a cleaning blade (cleaning step) to clean the surface of the organic photoreceptor. Return to original clean state. In the latent image forming step, the surface of the organic photoreceptor is charged to a uniform negative potential (charging step);
Next, an optical image of the document is projected onto the surface of the charged organic photoreceptor (exposure step), thereby forming an electrostatic latent image made of electrostatic charges on the surface of the organic photoreceptor. Specifically, in the charging step, the entire image forming area on the surface of the organic photoreceptor is heated to a temperature of -400 to -, for example, using a corona charger.
The organic photoreceptor is charged to a potential of about 1000 V, and in the exposure process, a light source, a reflecting mirror, a lens, etc. are provided on the surface of the organic photoreceptor whose surface is charged to a uniform negative potential by the charging process. A reflected light image or a transmitted light image of the original is formed by an exposure optical system, thereby forming a negative electrostatic latent image corresponding to the original on the surface of the organic photoreceptor. In the transfer step, an electrostatic transfer method can be preferably used. Specifically, for example, a transfer device that generates an alternating current corona discharge is placed so as to face an organic photoreceptor through a transfer material, and an alternating current corona discharge is applied to the transfer material from the back side of the organic photoreceptor. The toner carried on the surface of the transfer material is transferred to the surface of the transfer material. In the cleaning step, a cleaning blade is used. This cleaning blade is preferably made of urethane rubber, for example, and in this case, cleaning performance and durability are improved. The cleaning blade is usually placed in a state in which it is lightly and elastically pressed against the surface of the photoreceptor, and cleaning is accomplished by scraping off toner remaining on the surface of the photoreceptor. In order to facilitate cleaning, it is preferable to add a static elimination process to neutralize the surface of the organic photoreceptor before the cleaning process. This static elimination step can be performed, for example, using a static eliminator that generates AC corona discharge. In the fixing step, fixing is performed by a contact heating method using a heat roller fixing device having a heat roller coated with a fluorocarbon resin or a silicone resin. A heat roller fixing device usually includes a heat roller, a backup roller disposed in opposition to the heat roller, and a heat source for heating the heat roller, or a cleaning roller is further disposed in opposition to the heat roller. It consists of Specifically, the heat roller is made by coating a core material made of metal such as iron or aluminum with a coating layer made of a fluorocarbon resin or silicone resin such as Teflon (polytetrafluoroethylene manufactured by Dupont) on the surface of the core material. It is preferable to use the one provided and configured. Further, as the back-up roller, one which is constructed by providing a coating layer made of silicone rubber or the like on the surface of a metal core material can be preferably used. FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be suitably used to carry out the image forming method of the present invention. Reference numeral 30 denotes a cabinet, and at the top of the cabinet 30 there are provided a glass document table 32 on which a document 31 is placed, and a platen cover 33 that covers the document 31. Cabinet 3
A paper feed tray 41 on which transfer paper 40 is set is provided at one end of the printer 0, and a paper discharge tray 42 is provided at the other end.
is provided. 43 and 44 are paper feed rollers, and 45 is a paper discharge roller. Reference numeral 50 denotes an organic photoreceptor for forming a negative electrostatic latent image, and this organic photoreceptor 50 has a rotating drum shape. Around the organic photoreceptor 50, from the upstream side to the downstream side in the rotational direction,
In order, a corona charger 51, an exposure optical system 52, a magnetic brush developer 53, an electrostatic transfer device 54, and a separator 5.
5. A blade type cleaning device 56 is arranged. The exposure optical system 52 includes a light source 61 and a first mirror.
62, a second mirror unit 64 consisting of a pair of mirrors arranged in order along the optical path from the first mirror unit 63 to the organic photoreceptor 50, and a lens 65.
It consists of a mirror 66 and a dichroic mirror 67. The first mirror unit 63 is movably provided below the document placing table 32 so as to be scanned with respect to the document placing table 32, and the second mirror unit 64 is arranged to move from the document scanning point to the organic photoreceptor 50. The first mirror unit 63 is provided movably in accordance with the moving speed of the first mirror unit 63 so as to maintain a constant optical path length. When the original 31 placed on the original placing table 32 is illuminated by the slit-shaped illumination light scanned by the exposure optical system 52, the slit-shaped reflected light image of the original 31 sequentially formed by scanning is rotated. The images are sequentially projected onto the developing surface of the moving organic photoreceptor 50. 70 is a contact heating type heat roller fixing device;
This heat roller fixing device 70 has a heater 7 inside it.
3 is arranged, and this heat roller 7
1 and a backup roller 72 disposed so as to be in contact with the roller 1. In the above apparatus, the surface to be developed of the organic photoreceptor 50 is charged to a uniform negative potential by the corona charger 51, and then imagewise exposed by the exposure optical system 52 to the surface to be developed of the organic photoreceptor 50. A negative electrostatic latent image corresponding to the original is formed. This negative electrostatic latent image is then developed by the magnetic brush developing device 53 to form a toner image corresponding to the original. The toner image on the organic photoreceptor 50 is electrostatically transferred onto the transfer paper 40 by the electrostatic transfer device 54, and the toner image on the transfer paper 40 is heated and fixed by the heat roller fixing device 70 to form a fixed image. On the other hand, the surface of the organic photoreceptor 50 that has passed through the electrostatic transfer device 54 is rubbed by a blade-type cleaning device 56, and the toner remaining on the surface is scraped off, resulting in the original clean surface. In addition, it is subjected to the charging process by the corona charger 51 again. [Specific Examples] Specific examples and comparative examples of the present invention will be described below, but the present invention is not limited to these examples. (Production of inorganic fine particles) (1) Inorganic fine particles A (for the present invention) 20 parts by weight of the above-mentioned exemplary compound (1), which is a silane coupling agent having an epoxy group, is dissolved in 80 parts by weight of hexane, and the first treatment is carried out. A liquid was prepared. Next, 100 parts by weight of silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) was placed in a mixer, and while rotating, 100 parts by weight of the above-mentioned first treatment liquid was gradually added dropwise. These were placed in a flask and heated and dried for 1 hour while stirring, thereby obtaining inorganic fine particles whose surfaces were treated with a silane coupling agent having an epoxy group. Then, 20 parts by weight of hexamethylene diamine, which is an amino compound, was dissolved in 80 parts by weight of ethanol to prepare a second treatment liquid. 100 parts by weight of inorganic fine particles whose surfaces were treated with the epoxy group-containing silane coupling agent,
The particles were treated in the same manner as above using 100 parts by weight of the second treatment liquid to obtain inorganic fine particles whose surfaces were further treated with an amino compound. These are referred to as "inorganic fine particles A." This inorganic fine particle A is
The average particle diameter of the primary particles was 12 mμ, and the specific surface area by BET method was 96 m ² /g. (2) Inorganic fine particles B (for the present invention) A first treatment liquid was prepared by dissolving 15 parts by weight of the above-mentioned exemplary compound (2), which is a silane coupling agent having an epoxy group, in 85 parts by weight of hexane. Next, the same process as in the production of inorganic fine particles A was performed except that 100 parts by weight of this first treatment liquid was used to obtain inorganic fine particles whose surfaces were treated with a silane coupling agent having an epoxy group. Then, 15 parts by weight of diethylenetriamine, which is an amino compound, was dissolved in 85 parts by weight of ethanol.
A second treatment solution was prepared. 100 parts by weight of inorganic fine particles whose surfaces were treated with the epoxy group-containing silane coupling agent,
The particles were treated in the same manner as above using 100 parts by weight of the second treatment liquid to obtain inorganic fine particles whose surfaces were further treated with an amino compound. These will be referred to as "inorganic fine particles B". This inorganic fine particle B is
The average particle diameter of the primary particles was 7 mμ, and the specific surface area by BET method was 126 m ² /g. (3) Inorganic fine particles C (for the present invention) A first treatment liquid was prepared by dissolving 20 parts by weight of the above-mentioned exemplary compound (4), which is a silane coupling agent having an epoxy group, in 80 parts by weight of toluene. Next, 100 parts by weight of the first treatment liquid and silica fine particles "Aerosil 300" (manufactured by Nippon Aerosil Co., Ltd.) were added.
Except that 100 parts by weight was used, inorganic fine particles whose surfaces were treated with a silane coupling agent having an epoxy group were obtained in the same manner as in the production of inorganic fine particles A. Then, 10 parts by weight of triethylenetetramine, which is an amino compound, was dissolved in 90 parts by weight of ethanol to prepare a second treatment liquid. 100 parts by weight of inorganic fine particles whose surfaces were treated with the epoxy group-containing silane coupling agent,
The particles were treated in the same manner as above using 100 parts by weight of the second treatment liquid to obtain inorganic fine particles whose surfaces were further treated with an amino compound. This will be referred to as "inorganic fine particles C." This inorganic fine particle C is
The average particle diameter of the primary particles was 13 mμ, and the specific surface area by BET method was 75 m ² /g. (4) Inorganic fine particles D (for comparison) Silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated to 100℃, and amino group-containing silicone oil was added to the silica fine particles using isopropyl. Solution dissolved in alcohol (viscosity 1200 cps, amino equivalent
3500) was stirred at high speed while being sprayed at a rate such that the amount of the amino group-containing silicone oil treated was 2.0% by weight, and then dried at a temperature of 150°C, so that the surface was treated with the amino group-containing silicone oil. Inorganic fine particles for comparison were obtained. These are referred to as "inorganic fine particles D." (5) Inorganic fine particles E (for comparison) Silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated at 70°C, and an amino group-containing silane coupling agent was added to the silica fine particles. A solution of γ-aminopropyltriethoxysilane dissolved in alcohol was stirred at high speed while being sprayed at a rate such that the amount of the amino group-containing silane coupling agent treated was 5.0% by weight. Comparative inorganic fine particles were obtained which were dried at 120°C and whose surfaces were treated with an amino group-containing silane coupling agent.
These are referred to as "inorganic fine particles E." (6) Inorganic fine particles F (for comparison) A treatment solution was prepared by dissolving 20 parts by weight of the exemplary compound (1) in the production of inorganic fine particles A and 20 parts by weight of hexamethylene diamine in 160 parts by weight of hexane. , inorganic fine particles A to 100 parts by weight of silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.)
Comparative inorganic fine particles were obtained by processing in the same manner as above. These are referred to as "inorganic fine particles F."<Example1> (1) Production of toner 100 parts by weight of polystyrene-n-butyl acrylate copolymer (copolymerization weight ratio = 82:18) and carbon black "Mogull L" (manufactured by Cabot Co., Ltd.)
10 parts by weight of the dye and 2 parts by weight of the metal-containing dye were mixed in a V-type blender, then melt-kneaded with two rolls, cooled, coarsely ground with a hammer mill, finely ground with a jet mill, and then Classified using a wind classifier to determine the average particle size.
A non-magnetic toner of 11.0 μm was obtained. This is referred to as "toner 1". (2) Production of developer The inorganic fine particles A are added to 50 parts by weight of the above toner 1.
By adding 0.5 parts by weight of and mixing these with a Henschel mixer, inorganic fine particles are attached or implanted onto the surface of the toner particles and retained, and then iron powder "DSP138" (manufactured by Nippon Tetsuko Kogyo Co., Ltd.) is added to these. The electrostatic image developer of the present invention, which is a two-component developer, was obtained by mixing 950 parts by weight of the carrier. This will be referred to as "Developer 1". (3) Live-action test Γ Test 1 (live-action test under normal humidity environment conditions) An organic photoreceptor for forming a negative electrostatic latent image,
A contact type magnetic brush developer, a corona transfer device that generates alternating current corona discharge, a 30φ diameter heat roller whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by Dupont), and a silicone rubber surface layer "KE-1300RTV". ``U-Bix1550MR'' electrophotographic copying machine equipped with a heat roller fixing device made of a back-up roller made by Shin-Etsu Chemical Co., Ltd. and a cleaning device having a cleaning blade made of urethane rubber.
(manufactured by Konishiroku Photo Industry Co., Ltd.) at a temperature of 20
A photocopying test was carried out in which a copy image was continuously formed 30,000 times using the above developer 1 under normal humidity environmental conditions of 60% relative humidity and 60% relative humidity, and the following items were evaluated. The results are shown in Table 1 below. The above-mentioned photoreceptor has a negatively chargeable two-layer photosensitive layer formed using an anthrone-based pigment as a carrier generating substance and a carbazole derivative as a carrier transporting substance, and a rotating drum-shaped aluminum conductive support. It is constructed by laminating layers on the body. The surface potential (highest potential) of the organic photoreceptor when it is charged is -700V, the gap (Dsd) between the photoreceptor and the developing sleeve in the developing space is 0.9 mm, and the distance between the tip of the regulating blade and the developing sleeve ( Hcut) is 0.6 mm, the magnet is fixed, the magnetic flux density on the surface of the developing sleeve is 800 Gauss, and the bias voltage applied to the developing sleeve is a DC voltage of -
It is 100V. Fog This was determined by measuring the relative density of the white background area of the original with a density of 0.0 to the copied image using a "Sakura Densitometer" (manufactured by Konishi Roku Photo Industry Co., Ltd.). Note that the white background reflection density was set to 0.0. The evaluation is ``○'' when the relative concentration is less than 0.01, and 0.03 when it is 0.01 or more.
If it is less than 0.03, it is marked as "△", and if it is 0.03 or more, it is marked as "x". Image Density Using a "Sakura Densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.), the relative density of a white background area with an original density of 0.0 to a copied image was measured. Image quality The reproduced image has three characteristics: image omission, image unevenness, and clarity.
Judgment was made visually from two points. The evaluation was rated "x" if it was poor and had a practical problem, "△" if it was slightly poor but at a practical level, and "○" if it was good. Toner scattering Visually observe the inside of the copier and the copied images,
``○'' indicates that there is almost no toner scattering and is in good condition; ``△'' indicates that some toner scattering is observed but it is at a practical level; ``×'' indicates that there is a lot of toner scattering and there is a problem in practical use. ”. Cleanability After repeated image formation, the surface of the organic photoreceptor was visually observed immediately after being cleaned with a cleaning blade, and judgment was made based on the presence or absence of deposits on the surface of the organic photoreceptor. The evaluation is "○" if there is almost no deposits observed and the product is in good condition, "△" if some deposits are observed but at a practical level, and "△" if a lot of deposits are observed and there is a problem in practical use. was marked as "x". Durability of the fixing device Judgment was made based on the occurrence of offset development, occurrence of paper jams, and staining of the back side of the transfer paper caused by dirt on the heat roller and back-up roller that constitute the fixing device. The evaluation was rated "x" if it was poor and had a practical problem, "△" if it was slightly poor but at a practical level, and "○" if it was good. Γ Test 2 (live-action test under high-humidity environmental conditions) A live-action test was conducted in the same manner, except that the environmental conditions were a high-humidity environment with a temperature of 30°C and a relative humidity of 80%, and each of the above items was evaluated. . The results are shown in Table 2 below. <Example 2> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of inorganic fine particles B was used instead of inorganic fine particles A.
This will be referred to as "Developer 2". A photographic test was carried out in the same manner as in Example 1, except that this developer 2 was used, and evaluations were made in the same manner. The results are shown in Tables 1 and 2 below. <Example 3> A developer was obtained in the same manner as in Example 1, except that 0.6 parts by weight of inorganic fine particles C was used instead of inorganic fine particles A.
This will be referred to as "Developer 3". A photographic test was carried out in the same manner as in Example 1, except that this developer 3 was used, and evaluations were made in the same manner. The results are shown in Tables 1 and 2 below. <Comparative Example 1> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of Comparative Inorganic Fine Particles D was used instead of Inorganic Fine Particles A in producing the developer of Example 1. . This is referred to as "comparative developer 1." A photographic photographic test was carried out in the same manner as in Example 1, except that this comparative developer 1 was used, and evaluations were made in the same manner. The results are shown in Tables 1 and 2 below. <Comparative Example 2> A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of comparative inorganic fine particles E was used instead of inorganic fine particles A in producing the developer of Example 1. . This is referred to as "comparative developer 2." A photographic test was carried out in the same manner as in Example 1, except that this comparative developer 2 was used, and evaluations were made in the same manner. The results are shown in Tables 1 and 2 below. <Comparative Example 3> Inorganic fine particles A in the production of developer of Example 1
A developer was obtained in the same manner as in Example 1, except that 0.4 parts by weight of comparative inorganic fine particles F was used instead. This is referred to as "comparative developer 3." A photographic test was carried out in the same manner as in Example 1, except that this comparative developer 3 was used, and evaluations were made in the same manner. The results are shown in Tables 1 and 2 below.

【table】

[Table] As can be understood from the results in Tables 1 and 2, according to the developers 1 to 3 of the present invention, the toner has good triboelectric chargeability and fluidity. The negative electrostatic latent image formed on the organic photoreceptor by the magnetic brush development method can be developed well without toner scattering, and in the transfer process, the electrostatic transfer means can achieve a high transfer rate. In addition, in the cleaning process, a cleaning blade with a simple structure can perform good cleaning, and in the fixing process, a hot roller fixing device can perform good fixing without causing offset phenomenon. As a result, it is possible to form a good image with clear image quality without fogging, image missing, or image unevenness, and with high image density. Even when performing the image forming process many times, the heat roller and back-up roller in the heat roller fixing device do not get dirty, and the usable life of the roller is significantly extended.
Furthermore, good images can be stably formed even under high humidity environmental conditions. On the other hand, according to Comparative Developer 1, since comparative inorganic fine particles D whose surfaces were treated with amino group-containing silicone oil are used, the triboelectric charging properties of the toner are poor, resulting in a lot of fogging. This results in an unclear image with low image density. Furthermore, when the image forming process is repeated many times, the image becomes increasingly blurred and becomes a defective image at an early stage. In addition, according to Comparative Developer 2, since comparative inorganic fine particles E whose surfaces were treated with an amino group-containing silane coupling agent are used, the surface of the inorganic fine particles is completely coated with the amino group-containing silane coupling agent. Therefore, the negatively charged sites and hydrophilic sites of the inorganic fine particles remain, resulting in poor triboelectric charging properties of the toner, resulting in an unclear image with a lot of fog and low image density. Furthermore, the triboelectric charging properties become unstable due to the influence of humidity, and therefore, under high humidity environmental conditions, fogging occurs significantly, image density decreases considerably, and images become significantly blurred. Furthermore, according to Comparative Developer 3, since the coupling agent having an epoxy group and the amino compound are treated simultaneously, the reaction between the epoxy group and the amine occurs preferentially, producing a reaction product having a hydroxyl group, and the inorganic fine particles F There are many hydroxyl groups on the surface of the toner, which reduces the positive chargeability and makes it more susceptible to humidity.As a result, the triboelectricity of the toner becomes poor, resulting in an unclear image with a lot of fog and low image density. Become. In addition, triboelectric charging properties rapidly and unstablely decrease due to the influence of humidity, and as a result, under high-humidity environmental conditions, significant fogging occurs, image density decreases considerably, and images become unclear. It becomes noticeable. Furthermore, the reaction products tend to cause contamination, which contaminates the surface of the photoreceptor and the fixing roller, reducing cleaning performance and durability of the fixing device. Furthermore, when we conducted a continuous photographing test for 50,000 times using Developers 1 to 3 according to the present invention and applying the developing method according to the present invention, we found that Table 1 and 2
Good results similar to those shown in the table were obtained. In addition, when we conducted a continuous photographing test over 70,000 times using the developers 1 to 3 according to the present invention and applying the image forming method according to the present invention, the same good results as shown in Tables 1 and 2 were obtained. was gotten.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an electrostatic image developing apparatus that can be suitably used to carry out the electrostatic image developing method of the present invention, and FIG. FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be suitably used for the purpose of the present invention. 10...organic photoreceptor, 10A...conductive support, 10B...photosensitive layer, 11...developing sleeve,
12... Magnet body, 13... Regulation blade, 23...
...Developer layer (magnetic brush), 24...Development space,
30...cabinet, 31...manuscript, 32...
Original stage, 40...Transfer paper, 50...Organic photoreceptor, 51...Corona charger, 52...Exposure optical system, 53...Magnetic brush developer, 54...Electrostatic transfer device, 56... Blade type cleaning device, 70
...Heat roller fuser.

Claims (1)

[Scope of Claims] 1 Consists of silica fine particles whose surface has been treated with a silane coupling agent having an epoxy group and further treated with an amino compound represented by the following general formula (1), Particle size is 5~
500mμ, specific surface area by BET method is 20-500m ² /g
An electrostatic image developer comprising 0.1 to 5% by weight of inorganic fine particles mixed with a toner. General formula (1) (R ¹ , R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 9 or less carbon atoms, n
represents an integer from 1 to 4. ) 2 A negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor is treated with a silane coupling agent having an epoxy group, and then further treated with the following general formula (1). Consisting of silica fine particles treated with the amino compound shown, 1
Inorganic fine particles with an average particle size of 5 to 500 mμ and a specific surface area of 20 to 500 m ² /g by BET method,
An electrostatic image developing method characterized by developing with an electrostatic image developer mixed with a toner in an amount of 0.1 to 5% by weight. General formula (1) (R ¹ , R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 9 or less carbon atoms, n
represents an integer from 1 to 4. ) 3 A latent image forming step of forming a negative electrostatic latent image on the surface of a photoreceptor made of an organic photoconductive semiconductor, and a step of forming a negative electrostatic latent image on the surface of the photoreceptor, and treating the surface of the electrostatic latent image with a silane coupling agent having an epoxy group. Taue,
Furthermore, inorganic fine particles are made of silica fine particles treated with an amino compound represented by the following general formula (1), and have an average primary particle diameter of 5 to 500 mμ and a specific surface area of 20 to 500 m ² /g by the BET method. , toner
A development step of developing with an electrostatic image developer mixed with 0.1 to 5% by weight, a transfer step of electrostatically transferring the toner image obtained by development to a transfer material, and a surface of the photoreceptor after the transfer step. The toner image on the transfer material is heated and fixed by a heat roller fixing device having a heat roller coated with fluorine resin or silicone resin. An image forming method comprising: a fixing step. General formula (1) (R ¹ , R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 9 or less carbon atoms, n
represents an integer from 1 to 4. )