JP2005181658A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which exhibits a good low-temperature fixability even for a halftone image, is high in the generation temperature of a high-temperature offset, hardly causes offset and realizes uniform toner coating on a developer carrier and provides an image free from unevenness. <P>SOLUTION: The toner contains a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit, wherein the binder resin of the toner contains a component having a composition and a molecular weight which selectively dissolve in three solvents of THF, ethyl acetate and chloroform in specified amounts and a developer layer thickness regulating member is formed of a tabular ferromagnetic substance of ≤0.5 mm in the thickness of its front end facing a magnetic field generating means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a developing device and an image forming apparatus used in a recording method using an electrophotographic method, an electrostatic recording method, and an electrostatic printing method.

  Many electrophotographic methods are known as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. In general, a photoconductive material is used to form an electrostatic charge image on a photoreceptor by various means, and then the electrostatic charge image is developed with toner, and a toner image is formed on a transfer material such as paper as necessary. After the toner is transferred, the toner image is fixed on the transfer material by heating, pressure, heating and pressurization or solvent vapor. An example of such an image forming apparatus is shown in FIG. In the apparatus shown in FIG. 5, an electrostatic latent image is formed on the surface of the image carrier 10 by a charging device, an image exposure device, or the like (both not shown). The image carrier 10 is rotated to a position facing the toner carrier 21 of the developing device 19.

  The toner carrier 21 is a cylindrical member made of a conductive material such as metal. The toner carrier 21 holds the toner 30 in the toner containing portion 20 by a magnet 22 serving as a magnetic field generating means disposed inside, and is indicated by an arrow L. The toner 30 is conveyed to the vicinity of the electrostatic latent image on the image carrier 10 by rotating in the direction.

  This toner 30 is a magnetic toner, and is restrained by a magnetic field formed between the magnet 22 and the toner coat forming means 23 composed of a ferromagnetic material when being carried on the toner carrier 21 and transported. The surface of the body 21 is coated with a predetermined thickness, and in the toner coat forming process, the toner is given a charge of a predetermined polarity by frictional charging.

  Then, the magnetic toner 30 coated on the surface of the toner carrier 21 is applied to the surface of the image carrier 10 according to the electric field formed between the electrostatic latent image formed on the surface of the image carrier 10 and the toner carrier 21. Transferred to the electrostatic latent image to become a toner image, and transferred onto the transfer material 12 by the transfer means 11 of an electrostatic transfer system.

  In the image forming apparatus configured as described above, in order to improve the uniformity of the density of the halftone image, it is necessary to stably form a thin and uniform toner coat on the surface of the toner carrier 21. It is.

  In addition, various methods and apparatuses have been developed for the process of fixing the toner image, which is the final process described above, to a sheet as a transfer material. The most common method at present is a pressure heating method using a fixed heating heater via a heat roller or a heat-resistant film. The pressure heating method using a heating roller fixes the toner image by allowing the surface of the heat roller having releasability to the toner and the toner image surface of the fixing sheet to contact each other under pressure while passing through the fixing sheet. It is.

  In this method, the surface of the heat roller and the toner image on the fixing sheet come into contact with each other under pressure, so that the thermal efficiency when fusing the toner image on the fixing sheet is extremely good, and the fixing is performed quickly. Can do. Since the surface of the heating roller and the toner image are in contact with each other under a molten state and pressure, a part of the toner image adheres to and is transferred to the surface of the fixing roller, which is re-transferred to the next fixing sheet and stains the fixing sheet. The so-called offset phenomenon is greatly affected by the fixing speed and fixing temperature. In general, when the fixing speed is low, the surface temperature of the heating roller is set to be relatively low, and when the fixing speed is high, the surface temperature of the heating roller is set to be relatively high. This is to make the amount of heat applied from the heating roller to the toner to fix the toner substantially constant regardless of the fixing speed. Since the toner image on the fixing sheet has several toner layers, in a system where the fixing speed is particularly high and the surface temperature of the heating roller is high, the toner layer contacting the heating roller and the fixing target The temperature difference from the lowermost toner layer in contact with the sheet becomes large. Therefore, when the surface temperature of the heating roller is high, a phenomenon of high-temperature offset in which the toner on the uppermost layer is transferred to the heating roller is likely to occur, and when the surface temperature of the heating roller is low, the toner on the lowermost layer is sufficiently Since the toner does not melt, the toner is not fixed on the fixing sheet and a phenomenon of low temperature offset is likely to occur. In order to solve this problem, when the fixing speed is high, it is usual to increase the pressure at the time of fixing and anchor the toner to the fixing sheet.

  With this method, the temperature of the heating roller can be lowered to some extent, and the high temperature offset phenomenon of the uppermost toner layer can be prevented. However, since the shearing force applied to the toner becomes very large, a so-called wrapping offset phenomenon occurs in which the fixing sheet is wound around the fixing roller, or separation used for separating the fixing sheet from the fixing roller. The nail separation is likely to appear in the fixed image. Furthermore, since the pressure is high, the line image is crushed at the time of fixing, or the toner is scattered, so that the fixed image tends to deteriorate. Conventionally, vinyl copolymers such as polyester resins and styrene resins are mainly used as binder resins for toners.

  Polyester resins have excellent performance at low temperature fixability, but on the other hand, they have a problem that offset phenomenon is likely to occur at high temperatures. In order to compensate for this problem, attempts have been made to improve the viscoelastic properties by increasing the molecular weight of the polyester resin. In this case, however, there is a problem that the low-temperature fixability is impaired, and pulverization during toner production As a result, the binder resin becomes unsuitable for toner fine particles. Vinyl copolymers such as styrene resins are excellent in high-temperature offset resistance because of their excellent pulverization properties during toner production and easy high molecular weight, but they have a low molecular weight to improve low-temperature fixability. In addition, there is a problem that blocking resistance and developability deteriorate when the glass transition temperature is lowered.

  In order to make effective use of the advantages of these two types of resins and to make up for the drawbacks, several methods of mixing and using these resins have been studied. For example, Japanese Patent Laid-Open No. 54-114245 discloses a toner containing a resin obtained by mixing a polyester resin and a vinyl copolymer. However, since the chemical structure of the polyester resin and the vinyl copolymer are largely different, the compatibility is poor, and it is difficult to satisfy all of the low-temperature fixability, the high-temperature offset resistance, and the blocking resistance. Furthermore, it is difficult to uniformly disperse various additives added at the time of toner production, particularly wax, and not only the toner fixing performance but also developability is likely to occur. This problem becomes remarkable.

  Japanese Patent Application Laid-Open Nos. 56-116043 and 58-159546 disclose a toner containing a polymer obtained by polymerizing a monomer in the presence of a polyester resin. . JP-A-58-102246 and JP-A-1-156759 disclose a toner containing a polymer obtained by polymerizing a vinyl copolymer in the presence of an unsaturated polyester. Yes.

  Japanese Examined Patent Publication No. 8-16796 discloses a toner comprising a block copolymer obtained by esterifying a polyester resin having a specific acid value and a styrene resin having a specific acid value and a molecular weight. Yes. Japanese Patent Application Laid-Open No. 8-54753 discloses a toner in which the binder resin is composed of a condensation polymerization resin and a vinyl resin and has a specific chloroform insoluble content and a peak in a specific molecular weight range. In the above-described binder resin, the condensation polymerization resin and the addition polymerization resin can maintain a stable phase separation state. However, although the high-temperature offset resistance is improved to some extent with toners using these binder resins, the low-temperature fixability of the toner is still insufficient, and when the toner contains wax, the dispersion state of the wax is reduced. It is difficult to control. When a toner is used, there are still problems to be improved not only in low-temperature fixability but also in developability.

  JP-A-62-195681 and JP-A-62-195682 describe a developer composition for electrophotography comprising a vinyl resin-containing polyester resin containing a specific amount of vinyl resin relative to the polyester resin. doing. However, the binder resin used in these electrophotographic developer compositions is a mixture in which a vinyl resin is dispersed and mixed in a polyester resin, and satisfies the low temperature fixability and the high temperature offset resistance. It is difficult. Further, both the copying machine and the printer are required to improve image resolution and sharpness. For this purpose, it is effective to reduce the toner particle size.

  Toner with a smaller particle size has a relatively large amount of colorant (magnetic material) contained in the toner, making it difficult to maintain the low-temperature fixability of the toner, and developing properties are more severely restricted than before. become. The decrease in the low-temperature fixability of the toner is remarkable in the halftone portion. According to the inventor's study, the amount of toner that forms an image in the halftone portion is relatively small compared to the solid black portion, and a medium to high speed machine using a heat roll fixing device and This is remarkable in a medium to low speed machine using a pressure heating and fixing method using a fixed heating heater through a heat resistant film.

  Furthermore, recording apparatuses such as printers, copiers, and fax machines using electrophotographic technology are increasingly required to be smaller, faster, and more durable. Among them, once offset toner adheres and accumulates on the pressure roller facing the heat roll in the heat roll fixing method or on the pressure roller facing the heat resistant film in the pressure heating method. There is a phenomenon called "Roller dirt". If this phenomenon progresses and the accumulation amount increases, the paper is wound around the pressure roller and causes jamming. On the other hand, there is a demand for simplifying the fixing device and realizing high durability by removing the cleaning member that removes the offset toner in order to reduce the size. Therefore, in order to suppress the occurrence of the above-mentioned jam and realize the above-mentioned requirement, improvement of this pressure roller dirt is required.

  Therefore, even a toner having a small particle size with an increased content of a colorant (especially a magnetic substance) or a halftone image exhibits good low-temperature fixability, a high temperature offset generation temperature, and a toner that is difficult to offset In a toner containing a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit, a binder resin for the toner is required. Has been proposed to contain a certain amount of a component having a composition and molecular weight that can be selectively dissolved in three solvents of tetrahydrofuran (THF), ethyl acetate, and chloroform. The hybrid resin component described here means a resin in which a vinyl polymer unit and a polyester unit are chemically bonded. Specifically, a polyester unit and a vinyl polymer unit obtained by polymerizing a monomer having a carboxylic acid ester group such as (meth) acrylic acid ester are formed by a transesterification reaction, preferably a vinyl polymer. Is used to form a graft copolymer (or block copolymer) having a backbone polymer and a polyester unit as a branch polymer.

  The above proposal will be described in detail below.

  The amount of component insoluble in tetrahydrofuran (THF) indicates a large amount of molecular weight in the polyester unit of the polyester resin or hybrid resin, which represents the low temperature fixability of the toner. Moreover, when the component soluble in THF has a specific molecular weight and a specific molecular weight component, it has better low-temperature fixability. For this reason, the binder resin preferably contains 15 to 50% by weight of (W2) insoluble in THF, preferably 20 to 45% by weight, and more preferably 25 to 40% by weight. good. When the THF insoluble content is less than 15% by weight, the high temperature offset occurrence temperature of the toner is lowered, the hot offset resistance and the toner storage stability are deteriorated, and the THF insoluble content exceeds 50% by weight. In addition, the low-temperature fixability of the toner deteriorates.

  The THF soluble component has a main peak in a molecular weight region of 4000 to 9000, preferably in a molecular weight region of 5000 to 8500, and more preferably in a molecular weight distribution measured by gel permeation chromatography (GPC). Is preferably in a region having a molecular weight of 5000 to 8000. When the main peak is in a region having a molecular weight of less than 4000, the hot offset resistance of the toner may be deteriorated, and when the main peak is in a region having a molecular weight of more than 9000, the low-temperature fixability of the toner may be impaired. This is because it is not preferable. The component (A1) having a molecular weight of 500 to less than 10,000 is preferably contained in an amount of 35.0 to 65.0%, preferably 37.0 to 60.0%, more preferably 40.0 to 55. It is good to contain 0.0%. When the content of the component in the molecular weight region of 500 to less than 10,000 is less than 35.0%, the low-temperature fixability of the toner may deteriorate, and when it exceeds 65.0%, the toner is stored. This is because the properties may be deteriorated. The component (A2) having a molecular weight of 10,000 to less than 100,000 is preferably contained in an amount of 25.0 to 45.0%, preferably 27.0 to 42.0%, more preferably 30.0 to It is good to contain 40.0%.

  When the content of the component in the region having a molecular weight of 10,000 to less than 100,000 is less than 25.0%, the hot offset resistance of the toner may deteriorate, and when it exceeds 45.0%, the toner This is because the low-temperature fixability of the toner may deteriorate. The component (A3) having a molecular weight of 100,000 or more is preferably contained in an amount of 10.0 to 30.0%, preferably 12.0 to 25.0%, more preferably 15.0 to 22.0. % Content is good. When the content of the component in the region having a molecular weight of 100,000 or more is less than 10.0%, the hot offset resistance of the toner may deteriorate, and when it exceeds 30.0%, the toner is fixed at low temperature. This is because the properties may be deteriorated. The value of the ratio (A1 / A2) is preferably 1.05 to 2.00, preferably 1.10 to 1.90, more preferably 1.15 to 1.80. When the ratio (A1 / A2) is less than 1.05, the low temperature fixability of the toner may be deteriorated, and when it exceeds 2.00, the hot offset resistance of the toner may be deteriorated. This is because there is not.

  The amount of components unnecessary for ethyl acetate indicates the amount of a large molecular weight in the vinyl polymer unit of vinyl resin or hybrid resin, and not only toner fixability but also stable developability (for example, image density, fog, etc.) The dispersion state of the wax has a significant influence on imparting to the toner. The binder resin may contain 2 to 60% by weight of ethyl acetate insoluble (W4), preferably 5 to 50% by weight, and more preferably 10 to 40% by weight. If the ethyl acetate insoluble content is less than 2% by weight, there is a problem with the hot offset resistance of the toner, and it becomes difficult to control the dispersion amount of the wax contained in the toner. May decrease, which is not preferable. When the content of the ethyl acetate insoluble is more than 60% by weight, there is a problem in the low-temperature fixability of the toner, and the fog may become high due to durability, which is not preferable.

  The amount of components insoluble in chloroform is the amount of a component having a very large molecular weight of the vinyl resin, a component having a very large molecular weight in the polyester resin, and a component having a very large molecular weight in the hybrid resin component. Although closely related to the high temperature offset generation temperature, it is further related to a phenomenon (cleaning failure) in which the toner is fixed on the photosensitive member or the toner is not cleaned by a cleaning member such as a blade. The binder resin may contain 10 to 45% by weight of chloroform-insoluble component (W6), preferably 15 to 40% by weight, and more preferably 17 to 37% by weight. When the content of insoluble chloroform is less than 10% by weight, not only is there a problem with hot offset resistance, but fusion may occur, which is not preferable. When the content of the chloroform-insoluble component exceeds 45% by weight, not only a problem occurs in the low-temperature fixability of the toner but also a cleaning failure may occur, which is not preferable. The ethyl acetate insoluble component contains a component that dissolves in chloroform and an unnecessary component, and the ratio of the ethyl acetate insoluble component (W4) to the chloroform insoluble component (W6) contributes to durable image density. The ratio (W4 / W6) should be 1.1 to 4.0, preferably 1.2 to 3.5, and more preferably 1.5 to 3.0. Is good. In any case where the ratio (W4 / W6) is less than 1.1 or more than 4.0, the image density decreases due to durability.

  In the above toner, the wax is uniformly dispersed in the binder resin, the fixing property is good, the anti-offset property, the blocking resistance, and the durability of a large number of sheets under normal temperature low humidity or high temperature high humidity. Although it is excellent, it has a strong negative charge compared to a developer using polyester resin as a binder resin, so when used as a negative toner, the toner coat on the developer carrier due to overcharging becomes uneven. Unevenness is likely to occur in the image.

  The present invention has been made in view of the above problems. The object of the present invention is that the toner is used and the fixing property is good, the anti-offset property, the anti-blocking property, and the large number under normal temperature low humidity or high temperature high humidity. An object of the present invention is to provide a developing device and an image forming apparatus in which a toner coat on a developer carrying member due to overcharging is uniform and an image is not uneven even when used as a negative toner while maintaining sheet durability and the like.

To achieve the above objective,
(1) A developer having toner contained in a developer container is carried on the developer carrier by a magnetic field generating means inside the developer carrier, and a developer layer thickness regulating member is provided on the developer carrier. In the developing device that forms a developer layer and transports it to a development area facing the latent image carrier, develops the latent image on the latent image carrier with a developer, and visualizes the latent image carrier as the toner. Using at least a colorant, a binder resin and a wax, and the binder resin of the toner includes:
(A) a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit;
(B) 10-hour Soxhlet extraction using tetrahydrofuran (THF) as a solvent, containing 50 to 85 wt% (W1) of a THF-soluble component and 15 to 50 wt% (W2) of a THF-insoluble component,
(C) 10-hour Soxhlet extraction using ethyl acetate as a solvent, containing 40 to 98% by weight (W3) of an ethyl acetate soluble component, 2 to 60% by weight (W4) of an ethyl acetate insoluble component,
(D) Soxhlet extraction for 10 hours using chloroform as a solvent, containing 55 to 90% by weight (W5) of a chloroform-soluble component and 10 to 45% by weight (W6) of a chloroform-insoluble component,
(E) The value of W4 / W6 is 1.1 to 4.0,
(F) The molecular weight distribution of the THF-soluble component measured by gel permeation chromatography (GPC) has a main peak in the region of molecular weight 4000 to 9000, and the component in the region of molecular weight 500 to less than 10,000 is 35.0 to It is 65.0% (A1), the component in the region having a molecular weight of 10,000 to less than 100,000 is 25.0 to 45.0% (A2), and the component having a molecular weight of 100,000 or more is 10.0 to 30.0. % (A3), the value of A1 / A2 is 1.05 to 2.00,
A force that causes the developer to rise in a direction perpendicular to the developer carrier due to a facing corner of the developer layer thickness regulating member to the developer carrier and a magnetic field formed by the magnetic field generation unit is provided. A developing device comprising the developer layer thickness regulating member having a larger cohesive force than the developer on the developer carrying member.

  (2) The developer carrier has a base and a coating layer provided on the base, and the coating layer contains at least a binder resin, a conductive substance, and a quaternary ammonium salt compound. The developing device according to claim 1, wherein the binder resin includes at least one of an amino group, ═NH or —NH— in the structure.

  (3) The developer layer thickness regulating member is a member formed of a plate-like ferromagnetic material having a thickness of 0.1 mm or more and 0.5 mm or less at a tip facing the developer carrier. The developing device according to claim 1.

  The developer layer thickness regulating member is further developed as the developer layer thickness regulating member is further downstream from a corner on the downstream side in the rotation direction of the developer carrier among the opposing corners of the developer layer thickness regulating member to the developer carrier. 4. The developing device according to claim 1, wherein the layer thickness regulating member is a member formed so as to be separated from the developer carrying member.

  Therefore, according to the present invention, in a toner including a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit, the toner binder resin is tetrahydrofuran (THF). By using a toner containing a certain amount of a component having a composition and molecular weight that can be selectively dissolved in three solvents, ethyl acetate, and chloroform, the particle size of the colorant (particularly magnetic material) has been increased and the particle size has been reduced. Both toner and halftone images exhibit good low-temperature fixability, high temperature offset generation temperature is high, offset is difficult, and the thickness of the tip of the developer layer thickness regulating member facing the magnetic field generating means is 0 .Because it is a member made of a plate-like ferromagnetic material of 5 mm or less, the toner is restricted strongly at the toner restricting portion. Can enables good toner coat on the developer carrying member, a uniform image can be obtained.

  As described above, the present invention relates to a toner including a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit. (THF), ethyl acetate, and chloroform, a small particle size in which the content of the colorant (particularly the magnetic substance) is increased by using a toner containing a certain amount of a component having a composition and molecular weight that selectively dissolves in three solvents. Even if the toner is a halftoned image, it exhibits good low-temperature fixability, has a high temperature offset generation temperature, is difficult to offset, and the thickness of the tip of the developer layer thickness regulating member facing the magnetic field generating means Is a member made of a plate-like ferromagnetic material with a thickness of 0.5 mm or less. It is possible, it is possible to good toner coat on the developer carrying member, a uniform image can be obtained.

(Example 1)
An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a main part of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes an image carrier such as an a-Si photosensitive drum, and the image carrier 10 is rotatably arranged in the direction of an arrow K. Accordingly, the electrostatic latent image formed on the surface of the image carrier 10 by a charging device, an image exposure device, or the like (none of which is shown) is combined with the toner carrier 2 of the developing device 1 by the rotation of the image carrier 10. Carried to the opposite position.

  The toner carrier 2 in the present embodiment is a cylindrical member made of a conductive material such as aluminum and is rotatably arranged in the direction of an arrow L. Inside, a magnet 22 serving as a magnetic field generating means is fixedly arranged. It is installed.

  Further, the toner carrier 2 is formed by the base 40 of the toner carrier 2 being aluminum and the surface being formed by a phenol resin 41 in which carbon fibers 42 are dispersed. The carbon fiber content is suitably about 10 wt% to 60 wt% with respect to the resin. The volume resistivity of the resin layer in which carbon fibers are dispersed is appropriately about 1 to 100 Ωcm.

  As the toner 30 in the present embodiment, a toner produced by the following process is used.

1. Manufacture of low cross-linking resin composition-Terephthalic acid: 5.0 mol
-Succinic acid derivative represented by formula (1-3): 1.0 mol
-Trimellitic anhydride: 1.0 mol
・ PO-BPA: 7.0 mol
・ EO-BPA: 3.0 mol
The polyester monomer is charged into an autoclave together with an esterification catalyst, and is heated to 210 ° C. according to a conventional method while reducing pressure in a nitrogen atmosphere with a pressure reducing device, a water separator, a nitrogen gas introducing device, a temperature measuring device, and a stirring device. The polyester resin having a low crosslinking degree was obtained by performing the condensation polymerization reaction.

  Next, 80 parts by weight of the polyester resin obtained here, 16 parts by weight of styrene, 4 parts by weight of 2-ethylhexyl acrylate, and 0.3 parts by weight of dibutyltin oxide as an esterification catalyst were added to 50 parts by weight of xylene. It melted and swollen by heating to ° C. Under a nitrogen atmosphere, a solution obtained by dissolving 1 part by weight of t-butyl hydroperoxide as a radical polymerization initiator in 10 parts by weight of xylene was dropped over about 30 minutes. The temperature was further maintained for 10 hours to complete the radical polymerization reaction. Further, by depressurizing while heating and removing the solvent, a low cross-linking degree polyester resin, a vinyl polymer and a low cross-linking degree resin composition comprising a polyester unit and a hybrid resin component having a vinyl polymer unit are obtained. Obtained.

2. Production of highly crosslinked resin composition-Terephthalic acid: 2.0 mol
-Succinic acid derivative represented by formula (1-3): 4.0 mol
-Trimellitic anhydride: 4.0 mol
・ PO-BPA: 10.0 mol
-EO-BPA: 4.1 mol
The polyester monomer is charged into an autoclave together with an esterification catalyst, and equipped with a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device, and a stirring device, and heated to 210 ° C. in a nitrogen atmosphere under reduced pressure. By performing a condensation polymerization reaction, a highly crosslinked polyester resin was obtained.

  Next, 50 parts by weight of xylene, 80 parts by weight of the polyester resin obtained here, 10 parts by weight of styrene, 10 parts by weight of 2-ethylhexyl acrylate, 0.01 part by weight of divinylbenzene and 0.3 parts of dibutyltin oxide as an esterification catalyst. Part by weight was added and heated to 110 ° C. to dissolve and swell. Under a nitrogen atmosphere, a solution obtained by dissolving 1 part by weight of t-butyl hydroperoxide as a radical polymerization initiator in 10 parts by weight of xylene was dropped over about 30 minutes. The temperature was further maintained for 10 hours to complete the radical polymerization reaction. Further, by depressurizing while heating and removing the solvent, a highly crosslinked resin composition comprising a highly crosslinked polyester resin, a vinyl polymer and a hybrid resin component having a polyester unit and a vinyl polymer unit was obtained. .

3. Production of binder resin 60 parts by weight of a low crosslinking resin composition, 30 parts by weight of a high crosslinking resin composition, 5 parts by weight of styrene, 5 parts by weight of 2-ethylhexyl acrylate and 0.01 part by weight of divinylbenzene are added to 100 parts by weight of xylene. It was added and heated to 110 ° C. to swell and dissolve. Under a nitrogen atmosphere, a solution obtained by dissolving 1 part by weight of t-butyl hydroperoxide as a radical polymerization initiator in 10 parts by weight of xylene was dropped over about 30 minutes. The temperature was further maintained for 10 hours to complete the radical polymerization reaction. Further, by depressurizing while heating and removing the solvent, it comprises a low-crosslinking polyester resin, a high-crosslinking polyester resin, a vinyl polymerization method, and a hybrid resin component having a polyester unit and a vinyl polymer unit. A binder resin containing about 28% by weight of insoluble matter was obtained.

4). Production of toner: Binder resin: 100 parts by weight Azo-based iron complex compound (1): 2 parts by weight Magnetic iron oxide: 100 parts by weight (average particle size 0.2 μm, Hc 9.5 kA / m (120 oersted), σs = 75 Am ² / kg (75 emu / g), σr = 6 Am ² / kg (6 emu / g))
Wax (1): 5 parts by weight The above mixture was melt-kneaded with a biaxial extruder heated to 130 ° C., and the cooled mixture was coarsely pulverized with a hammer mill. The coarsely pulverized product was finely pulverized with a jet mill, and the obtained finely pulverized product was classified with an air classifier to obtain an externally added toner having a weight average diameter of 6.8 μm.

  Using this non-added toner, the soluble component and insoluble content of tetrahydrofuran (THF), ethyl acetate and chloroform contained in the binder resin were quantified by Soxhlet extraction, and the resin composition excluding the mixed wax was The THF-insoluble matter (W2) is 31% by weight, the ethyl acetate-insoluble matter (W4) is 34% by weight, the chloroform-insoluble matter (W6) is 15% by weight, and the ratio (W4 / W6) is 2. The chloroform insoluble matter (W6A) in the THF insoluble matter (W2) was 6.7% by weight, and the chloroform insoluble matter (W6B) in the ethyl acetate insoluble matter (W4) was 8.3% by weight. It was.

  When the molecular weight of the soluble component (W1) of tetrahydrofuran was measured by GPC, the molecular weight of the main peak was 4400, the component (A1) in the region having a molecular weight of 500 to less than 10,000 was 48.9%, and the molecular weight was 10,000 or more 10 The component (A2) in the region of less than 10,000 was 26.7%, the component (A3) in the region of molecular weight of 100,000 or more was 24.4%, and the ratio (A1 / A2) was 1.83.

To 100 parts by weight of the non-externally added toner, 1.0 part by weight of hydrophobic dry silica (BET = 200 m ² / g) was externally added using a Hensial mixer to obtain externally added toner 30.

  The toner 30 accommodated in the toner accommodating portion 20 is constrained by a magnetic field formed between the magnet 22 and the toner coat forming means 3 made of a ferromagnetic material, and is coated on the surface of the toner carrier 2. In this coat forming process, the toner rubs against the surface of the toner carrier 2 configured as described above, and is charged by frictional charging. However, in the toner 30 of this embodiment, compared with a normal developer using a polyester resin as a binder resin, the toner aggregates due to overcharging, and the toner coat on the toner carrier 2 becomes non-uniform. I understood.

  Here, the magnetic field formed by the magnet 22 and the toner coat forming means 3 and the binding force of the toner by the magnetic field will be described in detail.

  FIG. 6 shows a circumferential magnetic flux density distribution (vertical component Br) formed by the magnet 22.

  The magnetic field shown in FIG. 6 is only for magnets. FIG. 7 shows the magnetic field in the vicinity of the toner coat forming means 3 when the toner coat forming means 3 is opposed to this. As shown in FIG. 7, the magnetic field is concentrated on the toner coat forming means three corners a, and there is almost no magnetic field in the flat part b. The presence of the flat part b weakens the magnetic field concentration at the corner part a as compared with the case where there is no flat part b. For this reason, the toner is toner-to-toner and the toner and toner carrier 2 as in the toner 30 used in the present invention. And the toner coat becomes non-uniform due to the presence of the flat portion b.

In order to explain in more detail, FIG. 8 shows the state of toner spikes at the toner restricting portion of the flat plate blade as the conventional example and the knife edge blade as the present embodiment as the toner coat forming means 3, Make a comparison. In the figure, I is when a conventional flat blade is used, and II is when a knife edge blade is used. As shown in FIG. 8, in the case of the conventional flat blade, the magnetic field to the corners is weakened, so the force to make the toner rise is weak, and the toner and the toner carrier 2 or the cohesive force between the toners. Since it becomes weak, toner coat formation may not be performed well. In other words, the most important thing is a toner that easily aggregates due to overcharging like the toner used in this embodiment.
The force to make the toner spike> The toner coat forming means 3 is formed into a knife edge so that the cohesive force between the toner and the toner carrier 2 and the cohesive force between the toners are established. By doing so, the toner coat becomes normal.

Here, an example of a model experiment is shown. The force F1 that makes toner pop up is
F1 = αηB1 where α is a constant, η is a constant determined by the toner coat forming means 3, and B1 is a magnetic flux density of the magnet 22.

Further, the cohesion force F2 of the toner is
F2 = βB2, where B is a constant, and B2 is a limit magnetic flux density at which the toner does not cause a magnetic rearrangement phenomenon (rising).

  B2 is a flat electromagnet (10 cm × 10 cm in this case) that is infinitely large compared to the size of the toner, and an iron flat plate, which is a ferromagnetic material, is separated by 240 μm at the opposite part. This is the limit magnetic flux density that does not cause the rearrangement phenomenon when the toner is scattered in the meantime and the magnetic force of the electromagnet is increased, and is a value unique to the toner. The toner used in this example is 200 mT, The toner using polyester resin as a binder resin was 90 mT. Even if the toner is different, in order to satisfy F1> F2, it is necessary to increase η or B1, but it is very difficult to achieve this by increasing only B1, such as cost and manufacturing method. Therefore, it is necessary to raise η, and in order to raise η, it is necessary to make the toner coat forming means 3 into a knife edge.

  With the following configuration, η was increased and F1> F2 was achieved.

  In the present embodiment, the toner coat forming means 3 is formed of ferromagnetic iron, the thickness of the portion supported by the toner container 20 is 1.6 mm, and the tip of the portion facing the toner carrier 2 is formed. The toner coat forming means 3 was formed so as to have a thickness of 0.3 mm, and the tip of the toner coat forming means 3 was disposed so as to face the magnetic pole of the magnet 22.

  The toner coat forming means 3 is formed between the toner coat forming means 3 and the toner carrier 2 by using a shape in which the tip is sharply cut, as compared with the case of using a conventional flat toner coat forming means. Since the magnetic field to be concentrated is concentrated in a narrow area, the toner regulation power is strengthened. For this reason, in the configuration of the present embodiment, even when the toner 30 as described above is used, it is possible to perform a strong restriction on the toner 30 at the toner restriction portion, and the toner coat becomes uniform.

  FIG. 3 a shows the time dependency of the toner coat amount obtained by this embodiment. In FIG. 3, b is the time dependence of the toner coat amount obtained by the conventional apparatus (flat blade) shown in FIG. 5, and c is a conventional developer using polyester resin as a binder resin by the conventional apparatus shown in FIG. It depends on the amount of toner coating.

  As is apparent from FIG. 3, the toner coat of this embodiment is uniform. As a result, it is possible to obtain a toner coat having a very high uniformity such that the density of the halftone image is sufficiently uniform even with the toner 30 of the present embodiment, and at the same time, the fixing property is good, and the offset resistance, The blocking property and durability of a large number of sheets under normal temperature and low humidity or high temperature and high humidity can be maintained.

  Thus, the toner 30 coated on the surface of the toner carrier 2 adheres to the surface of the image carrier 10 in accordance with the electric field formed between the electrostatic latent image formed on the surface of the image carrier 10 and the toner carrier 2. After the toner image is formed, the toner image is satisfactorily transferred to the transfer material 12 by the transfer charging device 11.

  In the present embodiment, the thickness of only the tip of the toner coat forming means 3 is reduced, and the supported portion of the toner coat forming means 3 is thicker than the tip. This is to ensure linearity, and is not limited to the values and shapes described above as long as the linearity is maintained.

  For example, as the toner coat forming means 3 in the present invention, toner coat forming means 52 to 55 whose tip shapes are formed as shown in FIG. 4 may be used, and when these toner coat forming means are used. However, the effect similar to the above can be obtained. However, if the magnetic field is weakened as the toner coat forming means 3 used in the present embodiment is moved to the downstream side of the toner coat regulation, the concentration of the magnetic field at the corner on the downstream side is weakened, but the upstream side Magnetic fields were more concentrated on the corners, and toner coating was likely to be performed normally. Moreover, regarding the thickness of the tip, it was found that good results were obtained when the thickness was 0.5 mm or less and 0.1 mm or more.

  A method for determining the solvent-soluble component of the toner of the present invention and measuring other physical properties will be described below.

(1) Quantitative determination of toner insoluble components such as tetrahydrofuran (THF), ethyl acetate, and chloroform 2 g of toner (TW1) was precisely weighed (TW1), placed in a cylindrical filter paper (for example, No. 86R manufactured by Toyo Roshi Kaisha, Ltd.), and passed through a Soxhlet extractor. 200 ml is used. Reflux for 10 hours using an oil bath whose temperature is adjusted to about 120 ° C. The component soluble in THF (W1) can be quantified by concentrating and drying the THF, followed by vacuum drying at 60 ° C. for 24 hours. When the THF-insoluble component (W2) of the toner is quantified, it is calculated from the THF-insoluble component (TW2) other than the binder resin such as a colorant (magnetic material) by the following formula.

同様にして、溶媒を酢酸エチル及びクロロホルムに変更することにより、それぞれの溶媒に対する結着樹脂の可溶成分及び不溶成分を定量することができる。

Similarly, by changing the solvent to ethyl acetate and chloroform, the soluble component and insoluble component of the binder resin in each solvent can be quantified.

  An example of a Soxhlet extraction apparatus is shown in FIG.

  The THF 62 contained in the container 61 is heated and vaporized by the heater 63, and the vaporized THF is guided to the cooler 65 through the pipe 64. The cooler 65 is constantly cooled by cooling water 66. The THF cooled and liquefied by the cooler 65 accumulates in the storage unit 68 having the cylindrical filter paper 67, and when the liquid level of THF becomes higher than the middle tube 69, the THF is discharged from the storage unit to the container 61. The toner or resin contained in the cylindrical filter paper 67 is extracted by circulating THF.

Measurement of molecular weight distribution of binder resin raw material or toner binder resin The molecular weight of the chromatogram by GPC is measured under the following conditions.

The column is stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min. When the sample is a binder resin raw material, a material obtained by passing the binder resin raw material through a roll mill (130 ° C., 15 minutes) is used. When the sample is toner, the toner is dissolved in THF, filtered through a 0.2 μm filter, and the filtrate is used as a sample. Measurement is performed by injecting 50 to 200 μl of a THF sample solution of a resin adjusted to a sample concentration of 0.05 to 0.6% by weight. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Or a molecular weight of 6 × 10 ² , 2.9 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3 manufactured by Toyo Soda Kogyo Co., Ltd. .9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ are used, and it is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

As the column, in order to accurately measure the molecular weight region of 10 ^{3 to} 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, μ-styragel 500, 10 ³ , manufactured by Waters, A combination of 10 ⁴ and 10 ^{5 and} a combination of shodex KA801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK are preferable.

(Example 2)
In this embodiment, the toner carrier 2 is matched with the toner used in the present invention, and a more stable toner coat than that in the first embodiment is achieved.

  The toner carrier 2 used in the present example has a base and a conductive coating layer. On the surface of the base, a conductive substance, a quaternary ammonium salt compound that is positively charged with respect to iron powder, and A resin coating layer formed of a resin composition containing at least an amino group or a resin containing at least one of = NH and -NH- in the structure is provided. Hereinafter, an example of a resin coating layer (hereinafter also simply referred to as a coating layer) on the surface of the toner carrier 2 used in this embodiment will be described. As a binder resin that is a film forming material, it contains a quaternary ammonium salt compound that itself has a positive chargeability with respect to iron powder, and contains at least one of an amino group or = NH, -NH- in the structure. By using the binder resin, the negative chargeability of the binder resin itself of the coating layer increases, and the charge amount of the negatively chargeable toner can be controlled. Therefore, the coating layer formed on a cylindrical substrate made of metal or the like Is formed on the outer periphery of the cylindrical substrate with a resin containing at least one of an amino group or = NH, -NH- in the structure, which is a binder resin, and a conductive substance is contained in the coating layer. Yes. In some cases, a solid lubricant may be contained together with the conductive substance.

  Here, the relationship between the toner 30 and the coating layer in the developing device 1 will be described. Since the toner 30 used in the present invention has a strong negative chargeability as compared with a developer using a conventional polyester resin as a binder resin, toner coating unevenness is likely to occur on the toner carrier 2 due to overcharging. Therefore, if the toner carrier 2 provided with the coating layer is used, the amount of triboelectric charge imparted to the negatively chargeable toner can be controlled by the amount of addition of the quaternary ammonium salt compound. Can be effectively prevented and the toner 30 can be firmly adhered to the toner carrier 2. Furthermore, since the mechanical strength and wear resistance of the coating layer itself are improved compared to the case where the conventional charge imparting particles are added, it can withstand long-term durability and provide a good image stably for a long time. Is possible. As the quaternary ammonium salt compound having the above-mentioned function suitably used in the present invention, any compound may be used as long as it has a positive chargeability with respect to iron powder. And the compounds represented.

前述の一般式において、Ｘ⁻の酸イオンの具体例としては、有機硫酸イオン、有機スルホン酸イオン、有機リン酸イオン、モリブデン酸イオン、タングステン酸イオン、モリブデン原子或いはタングステン原子を含むヘテロポリ酸等が好ましく用いられる。構造中にアミノ基或いは＝ＮＨ、−ＮＨ−の少なくとも１つを含む樹脂に、本発明で用いる特定の第４級アンモニウム塩化合物を添加した樹脂組成物を使用して被覆層を形成すると、先に述べたように、結着樹脂である。構造中にアミノ基或いは＝ＮＨ、−ＮＨ−の少なくとも１つを含む樹脂を硬化させて被覆層を形成した場合に、該第４級アンモニウム塩化合物が樹脂の構造中に取り込まれる。このため、前記したネガ性シリカ粒子或いはネガ性テフロン（登録商標）粒子等のような粒子添加系の場合と異なり、部分的にではなく、被覆層全体として負帯電性現像剤に対しては過剰な負帯電付与性が抑制される。更に、粒子添加系の被膜と異なり、加工性が損なわれたり、被覆層の強度低下を生じることもない。

In the foregoing general formula, X ^- Specific examples of the acid ions, organic sulfate ions, organic sulfonate ions, organic phosphate ions, molybdate ions, tungstate ions, such as heteropoly acid containing molybdenum atoms or tungsten atoms Preferably used. When a coating layer is formed using a resin composition in which a specific quaternary ammonium salt compound used in the present invention is added to a resin containing at least one of an amino group or ═NH, —NH— in the structure, As described above, it is a binder resin. When a resin containing at least one of an amino group or = NH or -NH- is cured in the structure to form a coating layer, the quaternary ammonium salt compound is incorporated into the resin structure. For this reason, unlike the case of the particle addition system such as the negative silica particles or the negative Teflon (registered trademark) particles as described above, the coating layer as a whole is excessive in comparison with the negatively chargeable developer. The negative charge imparting property is suppressed. Further, unlike the particle-added coating, the processability is not impaired and the strength of the coating layer is not reduced.

  Accordingly, it is possible to provide a good image by using the developing device 1 having the toner carrier 2 provided with the coating layer formed using the binder resin. Furthermore, a stable image can be provided even in long-term durability.

  A method for manufacturing the toner carrier 2 used in this example will be described below.

Carbon 20 parts by mass Graphite 80 parts by mass A phenol resin produced using ammonia as a catalyst (solid content 50%)
480 parts by weight Quaternary ammonium salt compound (1) 60 parts by weight Methanol 160 parts by weight Sand mill the above materials with zirconia particles of φ2 mm for 3 hours, then separate the zirconia particles by sieving, and adjust the solid content to 30% with methanol Paint (c (carbon) / GF (graphite) / B (phenolic resin) / P (quaternary ammonium salt compound) = 0.2 / 0.8 / 2.4 / 0.6). This paint was sprayed to form a 10 μm film on an A1 cylinder having a diameter of 24.5 mm, and then heated and cured at 150 ° C./30 minutes with a hot air drier to produce a developer carrier.

  When the toner carrier 2 was used, a better toner coat was obtained.

1 is a cross-sectional view of a main part of an image forming apparatus according to an embodiment of the present invention. It is the schematic which shows one specific example of the Soxhlet extraction apparatus used for Soxhlet extraction. It is a figure which shows the difference of the toner coat on the toner carrier 2 in one Embodiment of this invention, and a prior art. It is a figure which shows the example of the cross-sectional shape of the toner control member of this invention. It is a principal part sectional view of a conventional image forming apparatus. It is the schematic of the magnetic field which the magnet 22 forms. 3 is a schematic diagram of a magnetic field formed by a magnet 22 and toner coat forming means 3. FIG. FIG. 6 is a schematic diagram showing how toner rises at a toner regulating portion with a flat blade and a knife edge blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing device 2 Toner carrier 3,52-55 Toner coat formation means 10 Image carrier 11 Transfer charging device (transfer means)
12 Transfer material 20 Toner container 22 Magnet (magnetic field generating means)
30 Toner

Claims (4)

A developer having toner contained in a developer container is carried on the developer carrier by magnetic field generating means inside the developer carrier, and a developer layer is regulated on the developer carrier by a developer layer thickness regulating member. In the developing device for transporting to a development area facing the latent image carrier, developing the latent image on the latent image carrier with a developer, and forming a visible image,
As the toner, a toner containing at least a colorant, a binder resin and a wax is used, and the binder resin of the toner includes:
(A) a vinyl resin, a polyester resin, and a hybrid resin component having a vinyl polymer unit and a polyester unit;
(B) 10-hour Soxhlet extraction using tetrahydrofuran (THF) as a solvent, containing 50 to 85 wt% (W1) of a THF-soluble component and 15 to 50 wt% (W2) of a THF-insoluble component,
(C) 10-hour Soxhlet extraction using ethyl acetate as a solvent, containing 40 to 98% by weight (W3) of an ethyl acetate soluble component, 2 to 60% by weight (W4) of an ethyl acetate insoluble component,
(D) Soxhlet extraction for 10 hours using chloroform as a solvent, containing 55 to 90% by weight (W5) of a chloroform-soluble component and 10 to 45% by weight (W6) of a chloroform-insoluble component,
(E) The value of W4 / W6 is 1.1 to 4.0,
(F) The molecular weight distribution of the THF-soluble component measured by gel permeation chromatography (GPC) has a main peak in the region of molecular weight 4000 to 9000, and the component in the region of molecular weight 500 to less than 10,000 is 35.0 to It is 65.0% (A1), the component in the region having a molecular weight of 10,000 to less than 100,000 is 25.0 to 45.0% (A2), and the component having a molecular weight of 100,000 or more is 10.0 to 30.0. % (A3), the value of A1 / A2 is 1.05 to 2.00,
The developer layer thickness regulating member is provided so that a magnetic restraining force for vertically arranging the developer on the surface of the developer carrying member is larger than a cohesive force of the developer on the developer carrying member. A developing device.   The developer carrier has a substrate and a coating layer provided on the substrate, and the coating layer contains at least a binder resin, a conductive substance, and a quaternary ammonium salt compound. The developing device according to claim 1, wherein the binder resin includes at least one of an amino group, ═NH or —NH— in the structure.   2. The developer layer thickness regulating member is a member formed of a plate-shaped ferromagnetic material having a thickness of 0.1 mm or more and 0.5 mm or less at a tip facing the developer carrying member. 2. The developing device according to 2.   The developer layer thickness regulating member is further developed as the developer layer thickness regulating member is further downstream from a corner on the downstream side in the rotation direction of the developer carrier among the opposing corners of the developer layer thickness regulating member to the developer carrier. 4. The developing device according to claim 1, wherein the layer thickness regulating member is a member formed so as to be separated from the developer carrying member.

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