JPH0145913B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic method for developing an electrostatic latent image using charged colored particles, and a developer used in the electrophotographic method. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Specification, Special Publication No. 42-23910 and Special Publication No. 43
A number of methods are known, as described in Japanese Patent Application No. 24748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the photoreceptor is A latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper and then fixed by heating, pressure, solvent vapor, etc. to obtain a copy. Various methods are also known for visualizing electrical latent images using toner. For example, the magnetic brush method described in US Pat. No. 2,874,096, the cascade development method described in US Pat. No. 2,618,522, and the powder cloud method and fur brush development method described in US Pat. No. 2,221,776, Many development methods are known, such as liquid development. The developed toner image is transferred and fixed onto a transfer material such as paper as necessary. Methods for fixing toner images include heating and melting the toner using a heater or heated roller to fuse and solidify it to the support, softening or dissolving the binder resin of the toner with an organic solvent, and fixing it to the support, and applying pressure. A method of fixing toner on a support by using a method is known. The toner used here has conventionally been a fine powder in which dyes and pigments are dispersed in natural or synthetic resin. Additionally, third substances may be added for various purposes. For example, in order to improve the developability of the developer, fluidity improvers such as colloidal silica, alumina, and talc powder, and substances with charge control properties such as dyes and pigments are used as charge control agents. Additionally, as durability progresses, the toner becomes excessively charged due to repeated friction and is strongly electrostatically attracted to the carrier or developing sleeve, preventing it from being peeled off by the developing electric field and preventing new toner from being charged. Therefore, in order to release a portion of the charge from the excessively charged toner, carbon black, fine metal powder, or fine metal oxide powder is externally added, or a surfactant or a polar solvent is sprayed. In addition, abrasives and lubricants such as Teflon powder, cerium oxide, vinylidene fluoride, and molybdenum disulfide are used to prevent toner from filming on the photosensitive plate or from sticking to the carrier or developing sleeve. used in conjunction with In this way, various substances are added to the developer for various purposes. The presence of these additives affects the performance of the developer, so an appropriate content rate must be determined, but during storage or durability, the additives deteriorate or are consumed outside the developing system. The desired performance may not be achieved.
For example, in the case of liquid development, the developer consists of toner, an inert non-polar liquid medium, and a charge control agent, but the charge control agent is exhausted by the toner during storage and must be replenished. There are things that must happen. Also,
Even in the dry development method, hydrophobic colloidal silica is often externally added as a fluidity improver, and it is very effective, but it deteriorates when subjected to large shearing forces in the developer and deteriorates. It may destabilize developability. Recently, a method of fixing toner under pressure has attracted attention in terms of energy saving, pollution-free, and immediacy of copying, and US Pat. No. 3,269,626,
There are proposals such as in Japanese Patent Publication No. 15876/1983, but because pressure-fixable toner uses a soft adhesive substance, it has very high cohesiveness, and although it is important to add a fluidity improver, it is not necessary to add external additives. The fine particles of the fluidity improver are incorporated into the binder resin of the toner, resulting in poor fluidity of the toner, resulting in a short lifespan. In order to recover the initial performance by externally adding a new fluidity improver, the concentration of the external additive in the replenishing toner should be made higher than the concentration of the external additive in the developer at the start of durability, or the external additive should be added as appropriate. It is possible to replenish additives into the developer, but this would be time-consuming and complicated, resulting in problems such as curling of paper due to high fixing pressure, excessive light selection of paper, changes in paper thickness, and fixing devices. Currently, hard toner binder resins are used at the expense of overlapping. An object of the present invention is to provide an electrophotographic method which has stable developing performance such as chargeability even after repeated use and has excellent durability. Another object of the present invention is to provide an electrophotographic developer that has stable developing performance such as chargeability even after repeated use and has excellent durability. Another object of the present invention is to provide an electrophotographic developer that does not deteriorate during storage and has excellent storage stability. Specifically, the present invention is an electrophotographic developer containing a toner and a microcapsule type additive, and the microcapsule type additive includes a fluidity improver, a charge control agent, or a conductive agent. The present invention relates to an electrophotographic developer, wherein the fluidity improver, the charge control agent, or the conductive agent is replenished into the developer from the microcapsule type additive during a development operation. Furthermore, the present invention provides an electrophotographic method in which an electrostatic latent image is visualized using a developer containing a toner and an additive, wherein the additive is a microcapsule type additive; The additive contains a fluidity improver, a charge control agent, or a conductive agent, and the fluidity improver, charge control agent, or conductive agent contained in the capsule-type additive is gradually released during the development operation. , relates to an electrophotographic method characterized in that it is replenished into a developer. In the present invention, the microcapsules contained in the developer actively develop the developer by acting as an encapsulated fluidity improver, charge control agent, or conductive agent to release excess charge from the toner. By gradually releasing substances involved in development properties into the developer, the amount of these additives involved in development properties in the developer is always kept at a constant level, stabilizing the development properties, and improving the developer properties. This aims to extend the lifespan of the product and improve its stability during storage. The release of the contents of the microcapsules can also be achieved by the liquid components or by the diffusion of the liquid within the microcapsule walls in the case of wet development, but generally, the release of the contents of the microcapsules is carried out by the diffusion of the liquid within the walls of the microcapsules in the case of a liquid component. This is done by destroying the microcapsule wall by force. For breaking the microcapsule walls, a separate stirring device having high shear force may be provided. The release of the contents of a microcapsule becomes slower as the wall of the microcapsule becomes thicker, as the degree of hardening of the wall increases, and as the particle size of the microcapsule becomes smaller. By combining capsules, it is possible to adjust the release of the inclusions during the durability period. When the encapsulated material is liquid, the microcapsules of the present invention can be produced by complex coacervation using gelatin/gum arabic, in-situ polymerization using an aminoplast prepolymer, or phase separation using cellulose resin. There are various well-known microencapsulation methods such as the method by which the encapsulation method can be applied, but if the encapsulated material is a powder, the powder is dispersed in a hydrophobic organic solvent in which the powder is insoluble. After making a slurry and dispersing this in-liquid slurry in water to form droplets, a semipermeable capsule wall is formed by interfacial polymerization, and the encapsulated liquid is extracted to the outside of the microcapsule, and then dried to form a powder. A method of making a microcapsule consisting of a capsule wall enclosing a capsule is suitable for the present invention. As the substance to be encapsulated in the microcapsules, colloidal silica or alumina powder is suitable as a fluidity improver, and those having an average primary particle size of 5 to 100 mμ are preferable. In addition, charge control agents include, for example, azo metal-containing dyes and metal bases of salicylic acid in the dry development method, and metal soaps, organic phosphorus compounds, organotin compounds, etc. in the wet development method. Examples of conductive agents that release some of the charge from charged toner include carbon black and aluminum powder, but tin oxide and zinc oxide semiconductors do not affect their performance due to humidity. suitable. The additive-containing microcapsule of the present invention has a weight ratio of the contained additive to the toner in the developer.
It is preferable to mix the additive into the toner in advance at a concentration of 0.05 to 10% by weight, and it can also be externally added to the developer as required. Unlike using it as a liquid, it is easy to handle without scattering powder or wetting the device with liquid. The toner particles used in the present invention are composed of a colorant, a binder resin, and the like. All known binder resins can be used, including monopolymers of styrene and its substituted products such as polystyrene, poly p-chlorostyrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, Styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, Styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α chloromethyl methacrylate copolymer , styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene - Styrenic copolymers such as acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, Polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl petyral, polymide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorine Chemicalized paraffin, paraffin wax, etc. can be used alone or in combination. Furthermore, various dyes and pigments such as carbon black are used in the toner for the purpose of color toning, charge control, etc. It is also used as a one-component magnetic toner by containing magnetic powder. Example 1 A mixture of (colloidal silica Aerosil R-972 (manufactured by Nippon Aerosil Co., Ltd.) 30 parts by weight toluene 100 parts by weight terephthalic acid dichloride 1.6 parts by weight) was dispersed in the following aqueous solution under stirring, and a Oil droplets were formed. Then, 20 ml of a 10% aqueous hexamethylene diamine solution was added dropwise, and stirring was continued for 4 hours. After the reaction is complete, the slurry is filtered, washed with water to remove residual polyvinyl alcohol, and finally washed with MeOH and dried.
A solid powder of microcapsules containing colloidal silica was obtained. (Polyvinyl alcohol 30 parts by weight Water 1000 parts by weight Sodium hydrogen carbonate 5 parts) Example 2 Polyethylene wax 50 parts by weight Charge control agent 2 parts by weight Magnetic material 50 parts by weight The above mixture was heated on a roll mill to 130°C. After cooling, the mixture was kneaded and crushed using a zigzag classifier to obtain a toner with an average particle size of 10 μm. Next, Example 1 was applied to 100 parts by weight of this toner.
A developer was obtained by mixing 1.2 parts by weight of microcapsules. Apply this developer to an electronic copying machine (manufactured by Canon, product name).
NP-120 (fixing pressure 25 kg/cm) was used for copy durability, and the maximum image density was within 1.2 ± 0.2 from the initial to 100,000 copies, and the images were clear. Comparative Example 1 The same procedure as Example 2 was carried out except that a fine powder of colloidal silica that was not microencapsulated was used instead of the colloidal silica-containing microcapsules, but the initial maximum image density exceeded 1.5. However, as the image density increased with durability, the image density decreased to below 0.5 after 10,000 sheets, and at the same time, areas where no toner was deposited appeared on the developing sleeve due to toner aggregation. Example 3 Example 1 was added to the developer of Comparative Example 1 after running for 10,000 sheets.
When we sprinkled 1.2 parts by weight of colloidal silica-containing microcapsules manufactured by Co., Ltd. and made 100 more copies, the areas on the developing sleeve where toner did not stick disappeared and the maximum image density recovered to 1.0. After that, the maximum image density reached 1.2 after 600 copies, and maintained at 1.2±0.2 until a total of 100,000 copies were taken.
The images were also clear. Example 4 20 g of gelatin having an isoelectric point of 8 was well dispersed in 160 g of cold water and then heated to 50° C. to completely dissolve it.
Next, 120 g of Isopar H 10% solution of polyaminopolybutenyl succinimide (trade name: Oloa 1200 manufactured by Caronite Chemical - charge control agent for wet development) was added to this aqueous gelatin solution using a homomixer (manufactured by Tokushu Kika Kogyo) for 30 minutes. The mixture was stirred and floated to obtain an emulsion of 30 to 100μ. Next, 20 g of gum arabic was dissolved in 160 g of water in the same manner as gelatin, and mixed with the emulsion solution with stirring. Then 20% NaOH
The aqueous solution was added dropwise to bring the pH value of the system to 10. After adding 500 g of 50°C warm water and stirring for 30 minutes, a 20% aqueous sulfuric acid solution was gradually added dropwise to lower the pH value of the system to 4.4. A gelatin-gum arabic composite layer was precipitated around the polyaminopolybutenyl succinimide-isopar solution droplets through phase separation.
When the gelatin-gum arabic composite layer, which was cooled to 5°C within 30 minutes, gelled, 3.8 g of a 30% formalin aqueous solution was added and stirred at that temperature for 30 minutes, then raised to 50°C for another 2 hours. Stirring was continued to harden the gelatin-gum arabic composite layer. After drying the obtained microcapsules by repeated filtration and water washing, gelatin containing a polyaminopolybutenyl succinimide-isopar solution was prepared.
A solid powder of gum arabic composite microcapsules was obtained. Example 5 Super Betsukasite 1126 (rosin modified phenol) 50 parts by weight AC polyethylene #6 (low molecular weight polyethylene)
50 parts by weight Regal 400R (carbon black) 15 parts by weight 250 ml of Isopar H After mixing the above substances, heat and confirm that they are completely and uniformly dispersed in a solution form. Mix with 500 ml of separately cooled Isopar H to finely disperse. This liquid was dispersed for 24 hours using a ball mill, and then an additional 500 ml of Isopar was added to form a condenser. Add 10 ml of the polyaminopolybutenyl succinimide-Isopar solution to the above condenser 1, and further add polyaminopolybutenyl succinimide-Isopar solution encapsulated gelatin prepared in Example 4.
Gum arabic composite microcapsules 20gr were added as a replenisher. Add 200ml of this replenisher to Isopar 2.
It was used as a diluted developer. When this developer was applied to a liquid development type transfer copying machine NP-6 (manufactured by Canon Inc.), it was found that very clear and high density (Dmax =
1.2) images were obtained. Add the above replenisher at 50°C.
When a developer was prepared in the same manner from a sample stored for several months and an image was produced in the same manner, the image density and good image quality remained the same as those newly prepared. Comparative Example 2 From a compactor prepared in the same manner as in Example 5,
A replenisher and a developer were prepared in the same manner as in Example 4, except that the gelatin-gum arabic composite microcapsules encapsulating the polyaminopolybutenylsuccinimide-isopar solution prepared in Example 4 were not added.
When this developer was applied to NP-6, a very clear and high density image (Dmax=1.2) was obtained.
When the replenisher was stored at 50°C for one month, a developer was prepared in the same manner as in Example 5, and an image was produced using NP-6. Only after adding 0.5 ml of polyaminopolybutenyl succinimide-isopar solution per solution, the original performance was finally exhibited. In order to compensate for this deterioration of the replenisher in advance, it is necessary to add at least 30 ml of polyaminopolybutenyl succinimide-isopar solution to the replenisher. All I could get was smudging and inferior images. Comparative Example 3 When image printing was performed using the toner prepared in Example 7 in the same manner as in Example 7 except that microcapsules containing conductive tin oxide were not added, the image density was low at room temperature and humidity. The decrease was very slight, but at extremely low humidity of 15° C. and 5% RH, it dropped to less than 0.5 after 10,000 to 20,000 sheets were printed, resulting in extremely sharp image quality. At this time, when a developer was added to the toner in an amount of 1% by weight of conductive tin oxide, the image density was restored to 1.0 and the edges became less noticeable. Under the same conditions, at the start of durability, 1
Even if % by weight of conductive tin oxide was added and the same toner was replenished during durability, the image density began to decrease after 30,000 to 40,000 sheets were printed. When the external addition amount of conductive tin oxide was increased to 4% by weight under the same conditions, the image density was initially low at 0.7, reached 0.9 from 8,000 to 10,000 sheets, and then remained almost constant. Ta. Comparing this result with the result of Example 7, the results are as follows. Example 6 A microorganism containing conductive tin oxide with a particle size of 10 to 100μ was prepared in the same manner as in Example 1, except that 20 parts by weight of conductive tin oxide and 40 parts by weight of toluene were used instead of 30 parts by weight of colloidal silica. Got the capsule. Example 7 Styrene-dimethylaminoethyl methacrylate copolymer 20 parts by weight Styrene-butadiene copolymer 80 parts by weight Carbon black 3 parts by weight The above materials were heated and kneaded in a roll mill, cooled and pulverized to form a toner with a particle size of 20 μm or less. I got it. A replenishing developer was prepared by adding 20 gr of the conductive tin oxide-encapsulating microcapsules prepared in Example 6 to 1 kg of this toner. 900 gr of iron oxide powder was added to 100 gr of this replenishment developer and mixed to prepare a starting developer. When this developer was applied to NP-8500 (manufactured by Canon Inc.) and images were produced continuously on 100,000 sheets while replenishing the above-mentioned replenishment developer, the image density was as high as the initial one (Dmax = 1.1), maintaining good image quality. This result remains unchanged even in an extremely low humidity environment of 15°C and 5% RH. 【table】

Claims (1)

[Scope of Claims] 1. An electrophotographic developer containing a toner and a microcapsule-type additive, the microcapsule-type additive containing a fluidity improver, a charge control agent, or a charge conductive agent. An electrophotographic developer, wherein the fluidity improver, the charge control agent, or the conductive agent is replenished into the developer from the microcapsule type additive during operation. 2 In an electrophotographic method in which an electrostatic latent image is visualized using a developer containing a toner and an additive, the additive is a microcapsule type additive, and the microcapsule type additive improves fluidity. a fluidity improver, which contains a charge control agent or a charge conductive agent, and is encapsulated in the capsule-type additive during the development operation;
An electrophotographic method characterized by gradually releasing a charge control agent or a conductive agent and replenishing it into a developer.