JP4176029B2 - Electrophotographic carrier, developer, image forming method, storage container, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a carrier, a developer, an image forming method, a storage container, an image forming apparatus, and a process cartridge used for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like.

  In general, in an image forming method such as electrophotography or electrostatic photography, an electrostatic latent image formed on a latent image carrier is developed with toner. As a method for developing an electrostatic latent image, a carrier is used. There are known a method of using a one-component developer not containing a toner and a method of using a two-component developer obtained by mixing a toner and a carrier.

  Up to now, there has been a large demand for space saving and cost reduction, and small printers, facsimiles, etc. have adopted a one-component development system, and printers, copiers, multifunction devices, etc. that require high speed and high image quality. In many cases, the two-component development method is adopted because of requirements such as toner charging stability and start-up property and long-term stability of image quality.

  Although the former one-component developing system has the advantage of being easily miniaturized, since the toner is charged using a charging member such as a blade or a roller, the tribocharging property is difficult to stabilize, and the charging member tends to deteriorate. Therefore, there is a problem that the life as an image forming apparatus is extremely short. On the other hand, the latter two-component development system can obtain a stable and good image, but has a problem that image fluctuation occurs due to carrier deterioration when used for a long time.

  Particularly in recent years, colorization of output images has progressed, and the demand for higher image quality and stabilization of image quality has become stronger than ever. Further enhancement of durability of the two-component developer is desired.

  The granular carrier used in such a two-component development system is such that toner filming on the carrier surface is prevented, carrier uniform surface formation, surface oxidation prevention, developer life extension, photoconductor carrier scratches or For the purpose of protection from abrasion, control of charge polarity, adjustment of charge amount, and the like, a hard and high-strength coating layer is usually provided by coating with a suitable resin material.

  For example, one coated with a specific resin material (Patent Document 1), one in which various additives are added to the coating layer (Patent Document 2), and one having an additive attached to the carrier surface (Patent Document 2) Patent Document 3) and those using a coating film containing conductive particles larger than the coating film thickness (Patent Document 4) are disclosed.

  Patent Document 5 describes that a benzoguanamine-n-butyl alcohol-formaldehyde copolymer is used as a main component for a carrier coating material, and Patent Document 6 describes a carrier coating with a cross-linked product of a melamine resin and an acrylic resin. The use as a material is described.

  However, the durability is still insufficient even when the above coating material is used, and there are problems such as spent on the carrier surface of the toner, destabilization of the charge amount associated therewith, and resistance reduction due to scraping of the coating resin, etc. Although a good image can be obtained in the initial stage, the image quality of the copied image decreases as the number of copies increases, so further improvement is required. According to Patent Document 7, the particle size and the binder resin film are required. It has been reported that these problems can be solved by defining the relationship of thickness and the resistivity of particles.

However, the effect described in Patent Document 7 is certainly more remarkable than the conventional ones, but the demand for the durability of recent developers is further increased, and further improvement is desired. Yes.

In recent years, both copiers and printers have many demands for space saving, and in response to this demand, measures have been taken to reduce the fixing portion by omitting fixing oil or by applying a small amount. In this case, since the toner has a toner configuration including a release agent, there is a great demand for a carrier having high durability even in combination with a toner including a release agent.
JP 58-108548 A JP 54-1555048 A JP-A-5-273789 JP-A-9-160304 JP-A-8-6307 Japanese Patent No. 2683624 JP 2001-188388 A

  The object of the present invention has been made in view of the above circumstances, and is to provide a more durable two-component developer carrier. Particularly, it is to provide a two-component developer carrier that is highly durable even in combination with a toner containing a release agent.

Means for solving the above problems are as follows.
(1) In a carrier having a coating film having at least a binder resin and particles, the particle diameter (D) and the film thickness (h) of the coating film have a relationship of 1 <[D / h] <10, An electrophotographic carrier, wherein the particles are surface-treated with one or more silane coupling agents represented by the following general formula (1) and having an oxyethylene unit and an alkyl group.

[However, at least one of X, Y, and Z is halogen or alkoxy (methoxy, ethoxy, etc.). R represents an alkyl group. n is an integer of 0-10. m is an integer of 2 to 20]
(2) In a carrier having a coating film having at least a binder resin and particles, the particle diameter (D) and the film thickness (h) of the coating film are in a relationship of 1 <[D / h] <10, The electrophotographic carrier characterized in that the coating film contains one or more silane coupling agents represented by the general formula (1) or (2) and having an oxyethylene unit and an alkyl group. .
(3) In a carrier having a coating film having at least a binder resin and particles, the relationship between the particle diameter (D) of the particles and the film thickness (h) of the coating film is 1 <[D / h] <10 The particles are surface-treated with one or more silane coupling agents having an oxyethylene unit represented by the general formula (1) or (2) and an alkyl group, and the coating film Containing one or more silane coupling agents having an oxyethylene unit represented by the general formula (1) or (2) and an alkyl group.
(4) The electrophotographic carrier according to any one of (1) to (3), wherein the resistivity of the particles is 10 ¹² (Ω · cm) or more and 10 ¹⁶ (Ω · cm) or less.
(5) The carrier for electrophotography according to (1) to (4), wherein the particles are alumina and / or silica.
(6) The electrophotographic carrier according to any one of (1) to (5), wherein the content of the particles is 40 to 95 wt% of the coating film composition component.
(7) The electrophotographic carrier according to (1) to (6), wherein the binder resin has a thickness of 0.05 to 1.00 μm.
(8) The binder resin for electrophotography according to any one of (1) to (7), wherein the binder resin contains at least a resin obtained by cross-linking an acrylic resin and an amino resin or / and a silicon resin. Career.
(9) An electrophotographic developer comprising: a toner comprising at least a binder resin and a pigment; and the electrophotographic carrier described in (1) to (8).
(10) The electrophotographic developer according to (9), wherein the toner contains a release agent.
(11) An image forming method using the electrophotographic developer according to (9) or (10).
(12) A multicolor image forming method using the electrophotographic developer according to (9) or (10).
(13) A developer storage container containing the electrophotographic developer according to (9) or (10).
(14) An image forming apparatus comprising the developer container according to (13).
(15) An image forming apparatus using the electrophotographic developer according to (9) or (10).
(16) A process cartridge using the electrophotographic developer according to (9) or (10).

  According to the present invention, conventional problems can be solved, and the following image forming method, developer storage container, image forming apparatus, and process cartridge can be provided.

1. In a carrier having a coat film having at least a binder resin and particles, the particle diameter (D) and the film thickness (h) of the coat film have a relationship of 1 <[D / h] <10, and the particles Is surface-treated with one or more silane coupling agents having an oxyethylene unit and an alkyl group represented by the general formula (1) or (2). Further, film scraping of the portion where the particles are present is suppressed, the charging function is stable over a long period of time, and a two-component developing carrier that is more durable than the conventional one can be obtained.
2. In a carrier having a coating film having at least a binder resin and particles, the particle diameter (D) and the film thickness (h) of the coating film are in a relationship of 1 <[D / h] <10. When the film contains one or more silane coupling agents represented by the general formula (1) or (2) and having an oxyethylene unit and an alkyl group, desorption of the particles, Film scraping of the portion where the particles are present is suppressed, the charging function is stable over a long period of time, and a two-component developing carrier that is more durable than the conventional one can be obtained.
3. In a carrier having a coat film having at least a binder resin and particles, the particle diameter (D) and the film thickness (h) of the coat film have a relationship of 1 <[D / h] <10, and the particles Is represented by the general formula (1) or (2) and is surface-treated with one or more silane coupling agents having an oxyethylene unit and an alkyl group, and the coating film is By containing one or more silane coupling agents represented by the general formula (1) or (2) having an oxyethylene unit and an alkyl group, the charging function is further stabilized over a long period of time. It is possible to obtain a two-component developing carrier having higher durability.
4). When the particle has a resistivity of 10 ¹² (Ω · cm) or more and 10 ¹⁶ or less (Ω · cm), even if the particle has a contact with the core material and is exposed on the surface, charge leakage Therefore, more stable chargeability can be obtained.
5. When the particles are alumina or / and silica, the effects when used as a protective material for the coating film resin and a surface shape adjusting material can be obtained more remarkably.
6). When the content of the particles is 40 to 95 wt% of the coating film composition component, the effects on durability and charging function are remarkable.
7). Sufficient durability can be obtained when the thickness of the coating film is 0.05 μm to 1.00 μm.
8). When the binder resin contains at least a resin obtained by cross-linking an acrylic resin and an amino resin or / and a silicon resin, the charge amount imparting ability is remarkably improved.
9. With the electrophotographic carrier, a two-component developer having higher durability than conventional one can be obtained.
10. By using the toner containing the electrophotographic carrier and the release agent, a two-component developer for an oilless image forming apparatus having higher durability than the conventional one can be obtained.
11. By using the two-component developer, an image forming method having higher durability than the conventional one can be obtained.
12 By using the two-component developer, a multicolor image forming method having higher durability than the conventional one can be obtained.
13. By storing the two-component developer, a developer storage container is provided. It is suitable for replenishing the developer, and a good image can be obtained over a long period of time.
14 By mounting the developer container, an image forming apparatus having higher durability than the conventional one can be obtained.
15. By using the two-component developer, an image forming apparatus having higher durability than the conventional one can be provided.
16. By using the two-component developer, a process cartridge having higher durability than the conventional one can be provided.

  Hereinafter, the present invention will be described in more detail. As a result of continuous studies to solve the above-described problems of the prior art, the present inventors have determined that the particle diameter (D) and the binding in a carrier having a coating film having at least a binding resin and particles. The resin film thickness (h) is 1 <[D / h] <10, and the particles are surface-treated with one or more silane coupling agents having an oxyethylene unit and an alkyl group, It was found that the improvement effect was remarkable.

  By including particles in the coating film, a convex portion is formed on the surface of the coating film, so that a strong impact is caused in contact with toner or contact between carriers caused by stirring for tribocharging the developer. Contact can be mitigated. As a result, it is possible to effectively suppress the spent of toner on the carrier, and it is also possible to prevent film abrasion of the binder resin, which is a charging generation location.

However, the convex portions, that is, the portions where the particles exist are alleviated from contact with a strong impact on the binder resin, so that the particles themselves are always easily detached from the coating film.
In addition, even when the particles do not detach from the convex portion, the surface of the particle at the convex portion is exposed or the toner spent at the convex portion is promoted when the film shaving of the convex portion proceeds. Therefore, when used for a long period of time, the charging function of the carrier tends to deteriorate.

  This phenomenon is remarkable particularly in a toner containing a release agent. The release agent used for the toner needs to be present on or near the toner surface in order to exhibit the releasability in the fixing process, and is not completely compatible with the toner binder resin. Material is used. For this reason, in a two-component developer containing a release agent, the toner release agent is likely to be selectively transferred to a carrier, and when a carrier containing particles is used in the coat film, a convex portion where the particles are present. There is a problem that due to the film scraping and the detachment of the particles, the spent portion proceeds and the charging function is lowered.

  Therefore, in order to cope with further high durability, it is necessary to suppress the detachment of the particles, and according to the present inventors, the particles are separated from the silane coupling agent having an oxyethylene unit and an alkyl group. By performing the surface treatment with one kind or two or more kinds, it is possible to suppress the detachment of the particles.

  This is due to the fact that the adhesion between the particles and the binder resin in the coating film is increased, so that the detachment of the particles and the film scraping of the portions where the particles are present are suppressed.

  In particular, in the case of a toner containing a release agent, the adhesion between the particles and the binder resin in the coating film is increased, so that the detachment of the particles and the film scraping of the portions where the particles exist are improved. Since the spent is prevented, the durability is remarkably improved as compared with the case where the particles are not surface-treated.

Further, according to the present inventors, it has been revealed that there is a suitable specific range for [D / h]. When [D / h] is 1 or less, the particles are buried in the binder resin. If it exceeds 10, the particles are likely to be detached.
A preferable range of [D / h] for impact relaxation and desorption prevention is 2 to 7.

  Conventionally, when [D / h] is 2 or more, it is not preferable because sufficient binding force cannot be obtained because the adhesion area between the particles and the binder resin is small, and the particles are easily detached. When the particles are surface-treated with one or more silane coupling agents having an oxyethylene unit and an alkyl group, the adhesion to the binder resin is increased, and [D / h] is 2 or more. However, the particles were not detached, and a convex portion could be formed on the coating film.

  Sufficient durability is obtained when the thickness of the coating film is 0.05 μm to 1.00 μm. When the thickness is 0.05 μm or less, the carrier core material is exposed due to film scraping, which causes carrier adhesion.

  Examples of the silane coupling agent having an oxyethylene unit and an alkyl group of the present invention include silane coupling agents represented by the following formula (1) or (2).

[However, at least one of X, Y, and Z is halogen or alkoxy (methoxy, ethoxy, etc.). R represents an alkyl group. n is an integer of 0-10. m is an integer of 2 to 20, preferably 6 or less. ]

  When the particle is surface-treated with the silane coupling agent, when a hydroxyl group or the like is present on the surface of the particle, the particle reacts with the hydroxyl group and is chemically bonded to the surface. Therefore, the particles preferably have a hydroxyl group on the surface, but these functional groups do not necessarily have to be present because the reactivity of the silane coupling agent is extremely high.

  The surface treatment of the particles with the silane coupling agent can be performed by either a dry method or a wet method. In the case of the dry method, the base metal oxide is charged into a high-speed stirrer such as a Henschel mixer or a super mixer, and the above-mentioned surface treatment solution is dropped or sprayed on the high-speed stirrer while uniformly stirring. Or may be added by spraying, stirred uniformly and then dried.

  In the case of a wet method, the particles and the surface treatment agent are added to a solvent, and after a dispersion treatment using a bead mill such as a ball mill, a coball mill, a sand grind mill, or a pearl mill, the solvent may be evaporated.

  In both methods, it is preferable to perform firing at 100 ° C. to 200 ° C. during or after the treatment to further strengthen the bond between the particles and the silane coupling agent.

  The ratio of the silane coupling agent to the particles in the present invention is influenced by the particle diameter and material (specific gravity) of the particles, the type of the silane coupling agent, etc., but is 0.01% with respect to 100 parts by weight of the particles before treatment. It is preferable that it is -100 weight part, More preferably, it is 3-50 weight part. If it is 0.01 parts by weight or less, sufficient adhesiveness with the binder resin cannot be obtained.

  Moreover, it replaces with surface-treating a silane coupling agent to this particle | grain, and the same effect is acquired even if it contains 1 type, or 2 or more types of a silane coupling agent in a coat film.

  In addition, when these particles are surface-treated and contained in a coating film, the effect is more remarkably exhibited.

  The content of these is desirably 0.01 to 50 parts by weight with respect to 100 parts by weight of the particles. More preferably 0.05 to 40 parts by weight is desirable.

According to the present invention, the resistivity of the particles is 10 ¹² (Ω · cm) or more and 10 ¹⁶ (Ω · cm) or less in order to suppress a decrease in charge amount during storage of the developer over a long period of time. It is valid. This is because when the particle size is 10 ¹² (Ω · cm) or more, even if the particles are exposed on the surface while having contact with the core material, charge leakage can be suppressed, so that stable chargeability can be obtained. .

On the other hand, when the resistivity of the particles is less than 10 ¹² (Ω · cm), since charge leakage cannot be suppressed, it is not preferable because stable chargeability cannot be obtained.

Any particles can be used as long as the particles have a weight average diameter of 10 μm or less and an intrinsic rate of 10 ¹² (Ω · cm) or more. In terms of affinity with the silane coupling agent, silica particles and alumina particles are preferable. As the silica particles and alumina particles, any known particles used as additives for toner can be used, but spherical silica particles or alumina particles having a weight average particle diameter of 1.0 μm or less are particularly preferable.

  Furthermore, when the particles are alumina and the content thereof is in the range of 40 to 95 wt% of the coating film composition component, preferably 70 to 90 wt%, the effect of stabilizing the charging property is remarkable. Similarly, when the particles are silica and the content thereof is in the range of 40 to 95 wt% of the coating film composition component, preferably 70 to 90 wt%, the effect of stabilizing the charging property is remarkable. A mixture of alumina and silica may also be used.

  When the content of the particles is less than 40 wt%, since the proportion of the particles occupies less than the proportion of the binder resin on the surface of the carrier particles, the contact with strong impact on the binder resin is reduced. This is not preferable because sufficient durability cannot be obtained.

  On the other hand, if it is more than 95 wt%, the proportion of the binder resin on the surface of the carrier is too much for the particles to occupy, so the proportion of the binder resin that is the charge generation location becomes insufficient, Insufficient charging ability. In addition, since the amount of particles is too large compared to the amount of binder resin, the ability to hold particles by the binder resin becomes insufficient, and the particles are easily detached, which is not preferable because sufficient durability cannot be obtained.

  Moreover, what contained the electroconductive particle larger than the film thickness of a coat film | membrane mentioned in the said background art in a coat film (patent document 4) differs from this invention about the content rate range of a particle | grain, In those described in Document 4, “0.01 to 50% by weight of the coating resin”, that is, “0.01 to 33.33 wt% of the coating film composition component” in terms of the content calculation method of the present invention. In this case, the durability is improved as compared with the conventional case. However, as described above, since the proportion of the particles occupies less than the proportion of the binder resin on the surface of the carrier particles, it is strong against the binder resin. The effect of alleviating contact with impact is small, and sufficient durability cannot be obtained.

  In the present invention, it is particularly preferable that the binder resin contains a resin obtained by crosslinking an acrylic resin and an amino resin or / and a silicon resin.

  As this amino resin, a conventionally known amino resin can be used. However, the use of guanamine or melamine remarkably improves the charge imparting ability.

  Also, a conventionally known silicon resin can be used as the silicon resin. In addition to the resins listed here, resins generally used as carrier coating resins can be used, and of course, they may be used in combination with the above resins. For example, polystyrene resin, poly (meth) acrylic resin, polyolefin resin, polyamide resin, polycarbonate resin, polyether resin, polysulfinic acid resin, polyester resin, epoxy resin, polybutyral resin, urea Resins, urethane / urea resins, polyethylene resins, Teflon (registered trademark) resins, and other thermoplastic resins and thermosetting resins, and mixtures thereof, as well as copolymers, block polymers, and graft weights of these resins Examples include, but are not limited to, coalescence and polymer blends.

  It is good to use what has Tg of resin as these raw materials of 20-100 degreeC, Preferably it is 25-80 degreeC. When the Tg of the resin is within this range, the resin has an appropriate elasticity. When the coating film is formed using the resin, the friction between the toner and the carrier in the stirring for tribocharging the developer. Alternatively, in the case of contact with a strong impact on the binder resin due to friction between the carriers, the impact can be absorbed, and the coating film can be maintained without being damaged.

  Moreover, when Tg is 20 ° C. or lower, the binder resin is blocked even at room temperature, which is not preferable because the storage stability is poor and it cannot be used practically. On the other hand, when Tg is 100 ° C. or higher, the binder resin is hard and brittle, and the impact cannot be absorbed, and the binder resin is scraped from the brittleness and the particles can be retained. Therefore, it is not preferable because it is easily detached.

  In the present invention, if necessary, conductive fine particles may be present in the coating film as a resistance adjusting agent. The conductive fine particles are also treated in the same manner as the above-mentioned particles. It doesn't matter. This treatment stabilizes the dispersion state of the conductive fine particles in the coat film. In particular, in the case of colored conductive fine particles, it is possible to suppress color stains of the color developer.

  Examples of the conductive fine particles used in the present invention include metals and alloys thereof, metal oxides, metal and metal oxides deposited on the surface of plastic particles, and carbon black. Examples of metals and alloys include aluminum, zinc, copper, chromium, nickel, stainless steel, and silver, and alloys thereof. Examples of metal oxides include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and oxide. Examples thereof include bismuth, tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide. These can be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion. In the present invention, among the conductive particles as described above, it is particularly preferable to use a metal oxide in terms of transparency. Among these, tin oxide, indium oxide, indium oxide doped with tin, and tin oxide doped with antimony are more preferable.

  Any carbon black that is generally used for carriers or toners can be used.

  As a carrier core material, a carrier core having a size of at least 15 μm (weight average particle diameter) is used from the viewpoint of preventing carrier adhesion (scattering) to the electrostatic latent image carrier to prevent occurrence of carrier streaks, etc. From the standpoint of preventing image quality degradation, a maximum of 100 μm is used.

  Specific materials that are known as two-component carriers for electrophotography, such as ferrite, magnetite, iron, nickel, etc., may be appropriately selected according to the use and purpose of use of the carrier.

  The carrier of the present invention is used as a two-component developer composed of toner, but the composed toner may be black toner or multicolor toner used in the multicolor image forming method.

  The image forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an image forming apparatus in which a container filled with a developer using the electrophotographic carrier of the present invention is mounted, and a developing section (within a main body of the image forming apparatus) 1), a developer storage container (2) filled with a developer using the electrophotographic carrier of the present invention replenished to the developing section (1), and a developer feed means (3) for connecting the two. FIG.

  In FIG. 1, the developing section (1) is a development filled with a developer using the electrophotographic carrier of the present invention containing a liquid two-component developer (D) formed by mixing a toner and a carrier. The developing roller (7) includes a housing (4), first and second stirring screws (5) and (6) for stirring and mixing the developer (D), and a developing roller (7). Is disposed to face the photosensitive member (8) of the latent image carrier. The photoconductor (8) is rotationally driven in the direction indicated by the arrow, and an electrostatic latent image is formed on the surface thereof. Reference numeral (26) in the drawing denotes a cap fitted on the connecting member (24) with or without the filter (25). Around the photosensitive member (8), other well-known units such as a charging unit, an exposure unit, a transfer unit, a charge removing unit, and a cleaning unit (not shown) are arranged.

  As the first and second agitating screws (5) and (6) rotate, the developer (D) in the developing housing (4) is agitated, and the toner is triboelectrically charged with opposite polarity to the carrier. . The developer (D) is supplied to the peripheral surface of the developing roller (7) that is rotationally driven in the direction of the arrow, and the supplied developer is carried on the peripheral surface of the developing roller (7). It is conveyed in the rotation direction by the rotation of 7).

  Next, the amount of the conveyed developer is regulated by the doctor blade (9), and the regulated developer is conveyed to the development area between the photosensitive member (8) and the developing roller (7), where The toner in the developer is electrostatically transferred to the electrostatic latent image on the surface of the photoreceptor, and the electrostatic latent image is visualized as a toner image.

Next, the process cartridge of the present invention will be described.
FIG. 2 shows a schematic configuration of an image forming apparatus having a process cartridge having the developer of the present invention. In FIG. 2, (31) shows the entire process cartridge, (32) shows a photosensitive member, (33) shows charging means, (34) shows developing means, and (35) shows cleaning means.

  In the present invention, a plurality of components such as the above-described photoreceptor (32), charging means (33), developing means (34), and cleaning means (35) are integrated as a process cartridge. The process cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

  In the image forming apparatus having the process cartridge having the two-component developer of the present invention, the photosensitive member is rotationally driven at a predetermined peripheral speed. In the rotation process, the photosensitive member is uniformly charged with a predetermined positive or negative potential on its peripheral surface by the charging unit, and then image exposure light from an image exposing unit such as slit exposure or laser beam scanning exposure. In this way, an electrostatic latent image is sequentially formed on the circumferential surface of the photosensitive member, and the formed electrostatic latent image is then toner developed by the developing means, and the developed toner image is exposed from the paper feeding unit. The transfer unit sequentially transfers the image to the transfer material fed in synchronization with the rotation of the photosensitive member between the transfer unit and the transfer unit. The transfer material that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means, and fixed on the image, and printed out as a copy (copy). The surface of the photoconductor after the image transfer is cleaned by removing the transfer residual toner by a cleaning means, and after being further neutralized, it is repeatedly used for image formation.

Hereinafter, methods for measuring various physical property values defined in the present invention will be described.
<Measurement of particle size>
The method for measuring the particle diameter of the particles defined in the present invention is not particularly limited, but a known general method is used, and for example, it is measured by a particle size distribution measuring apparatus of a laser scattering method or a centrifugal sedimentation method. Moreover, a particle size means a weight average diameter.

<Measurement of coating film thickness>
The measurement of the film thickness of the coating film defined in the present invention can observe the coating film covering the carrier surface by observing the cross section of the carrier with a transmission electron microscope. The thickness of the coat film is used.

<Measurement of resistivity>
A portion shown as 47 of the measurement cell A shown in FIG. 3 is filled with the sample, the lower electrode 41 and the upper electrode 42 are connected so as to be in contact therewith, and a voltage is applied between the electrodes. The current flowing at that time is measured to determine the resistivity. In this method, since the object to be measured is a powder, the filling rate changes, and the resistivity may change due to the change. The resistivity measurement conditions in the present invention were such that the contact area S between the filled particles and the electrode was about 2.3 cm ² , the thickness was about 1 mm, the load on the upper electrode 2 was 275 g, and the applied voltage was 100V.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these.

<Synthesis of silane coupling agent>
Silane coupling agents A and B having an oxyethylene structure and a long-chain alkyl group were synthesized by the following route.
(Synthesis of silane coupling agent A)

(Synthesis of silane coupling agent B)

(Example of toner production)
<Toner Production Example 1>
Black toner 1
Water 1200 parts Phthalocyanine green water-containing cake (solid content 30%) 200 parts Carbon black (MA60, manufactured by Mitsubishi Chemical Corporation) 540 parts Stir well with a flasher. Add 1200 parts of epoxy resin (Mn; 3500) here, knead at 150 ° C. for 30 minutes, add 1000 parts of xylene, knead for 1 hour, remove water and xylene, roll cooled and pulverized with pulverizer, master batch pigment Got.
next,
Epoxy resin (Mn; 3500) 100 parts Masterbatch 5 parts
3,5-di-t-butylsalicylic acid zinc salt 4 parts (Bontron E84, Orient Chemical)
The above materials were mixed with a mixer and then melt kneaded with a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization and classification were performed to obtain black particles having a weight average particle diameter of 7.8 μm. Further, 0.5 parts by weight of hydrophobic silica and 0.5 parts by weight of hydrophobic titanium oxide are added to 100 parts by weight of the colored particles, mixed with a Henschel mixer, passed through a sieve, and black toner 1 is obtained. Obtained.

<Toner Production Example 2>
Black toner 2
In Toner Production Example 1, everything was produced in the same manner as in Production Example 1 except that 5 parts of carnauba wax was added.

<Surface treatment particle production example 1>
Alumina particles 1
To a solution consisting of 10 parts by weight of silane coupling agent A and 300 parts by weight of methanol, 100 parts by weight of alumina (0.3 μm, resistivity 10 ¹⁴ Ω · cm) particles were added and stirred for 2 hours, followed by filtration to remove the solvent. Thereafter, drying was performed at 140 ° C. for 2 hours to obtain alumina particles 1 surface-treated with the silane coupling agent A.

<Carrier production example 1>
Career 1
Acrylic resin solution (solid content 50% by weight) 80 parts Guanamin solution (solid content 77% by weight) 25 parts Alumina particles 1 230 parts Toluene 1300 parts Butyl cellosolve 1300 parts Prepared. A sintered ferrite powder [Mn ferrite: average particle size: 35 μm (manufactured by Powdertech Co., Ltd.)] is used as a core material, and the above-mentioned coating film forming solution is spiral coater (Okada Seiko Co., Ltd.) so that the film thickness is 0.15 μm on the core material surface. Applied and dried. The obtained carrier was baked by standing in an electric furnace at 300 ° C. for 2 hours to cause a crosslinking reaction of the binder resin. After cooling, the ferrite powder bulk was pulverized using a sieve having an opening of 100 μm, and carrier 1 was obtained.

<Carrier production example 2>
Career 2
Acrylic resin solution (solid content 50% by weight) 80 parts Guanamin solution (solid content 77% by weight) 25 parts Alumina particles (0.3 μm, resistivity 10 ¹⁴ Ω · cm) 230 parts Silane coupling agent A 1 part Toluene 1300 parts 1300 parts of butyl cellosolve Except having changed into the above-mentioned prescription, everything was manufactured similarly to carrier manufacture example 1, and carrier 2 was obtained.

<Carrier Production Example 3>
Career 3
A carrier 3 was obtained in the same manner as in Production Example 2 except that the alumina particles described in Carrier Production Example 2 were changed to the surface-treated alumina particles 1 described in Carrier Production Example 1.

<Carrier Production Example 4>
Carrier 4
Acrylic resin solution (solid content 50 wt%) 80 parts Guanamine solution (solid content 77 wt%) 25 parts of alumina particles (0.3 [mu] m, resistivity 10 ¹⁴ Ω · cm) in 230 parts of toluene 1300 parts Butyl cellosolve 1300 parts The above formulation A carrier 4 was obtained in the same manner as in Carrier Production Example 1 except that the carrier was changed.

<Example 1>
The carrier 1 and the black toner 1 were placed in a ball mill and mixed for 10 minutes so that the toner concentration would be 7% to obtain a developer. This developer and black toner 1 were set in a commercially available digital full-color copying machine (imageColor 2800 manufactured by Ricoh Co., Ltd.), and 1,000,000 sheets were evaluated for running. Table 1 shows the results of calculating the amount of charge reduction and the amount of resistance reduction of the carrier after the running.

  The amount of charge reduction referred to here is a 95% by weight of the initial carrier mixed with a toner at a ratio of 5% by weight and triboelectrically charged to a general blow-off method [manufactured by Toshiba Chemical Co., Ltd .: TB- 200], the amount of charge (Q2) measured by the same method as that described above for the carrier obtained by removing the toner in the developer after running by the blow-off device from the charge amount (Q1) measured in step 200]. This is the amount subtracted, and the target value is 7.0 (μc / g) or less. Further, since the cause of the decrease in the charge amount is the toner spent on the carrier surface, the decrease in the charge amount can be suppressed by reducing the toner spent.

  The amount of resistance decrease is a value obtained by converting an initial carrier into a resistance measurement parallel electrode: an electrode having a gap of 2 mm, applying a DC 200V and measuring a resistance value after 30 seconds with a high resist meter into a volume resistivity ( R1) is the amount obtained by subtracting the value (R2) measured by the same method as the resistance measuring method from the carrier that can remove the toner in the developer after running by the blow-off device. The value is 2.0 [Log (Ω · cm)] or less. In addition, since the cause of the resistance reduction is scraping of the binder resin film of the carrier, the resistance reduction amount can be suppressed by reducing the film scraping.

<Example 2>
Evaluations were made in the same manner as in Example 1 except that the black toner 1 of Example 1 was changed to black toner 2. The evaluation results are shown in Table 1.

<Example 3>
Evaluations were made in the same manner as in Example 2 except that carrier 1 in Example 2 was changed to carrier 2. The evaluation results are shown in Table 1.

<Example 4>
Evaluations were made in the same manner as in Example 2 except that the carrier 1 in Example 2 was changed to the carrier 3. The evaluation results are shown in Table 1.

<Comparative Example 1>
Evaluations were made in the same manner as in Example 1 except that the carrier 1 in Example 1 was changed to the carrier 4. The evaluation results are shown in Table 1.

<Comparative example 2>
All the evaluations were made in the same manner as in Example 2 except that the carrier 2 in Example 2 was changed to the carrier 4. The evaluation results are shown in Tables 1 and 2.

  From Table 2, it can be seen that by using the carrier of the present invention, an effect of improving the durability as compared with the conventional carrier can be obtained. Further, it can be seen that the effect of improving the durability is remarkable as compared with the conventional carrier, particularly in combination with a toner containing a release agent.

  In the present invention, a carrier and a two-component developer used for electrostatic image development in electrophotography, electrostatic recording, electrostatic printing, and the like can provide a developer that is more stable for a longer time than before. In addition, since it is more durable than conventional ones, the load on the environment can be reduced.

1 shows a container filled with an electrophotographic developer of the present invention and an image forming apparatus equipped with the container. A conceptual explanatory view of a process cartridge is shown. FIG. 3 is a conceptual explanatory diagram of a resistivity measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing part 2 Developer storage container 3 Developer delivery means 4 Developing housing 5 Stirring screw 6 Stirring screw 7 Developing roller 8 Photoconductor 9 Doctor blade 24 Connection member 25 Filter 26 Cap D Developer 31 Entire process cartridge 32 Photosensitive Body 33 charging means 34 developing means 35 cleaning means

41 Lower electrode 42 Upper electrode 43 Insulator 44 Ammeter 45 Voltmeter 46 Constant voltage device 47 Sample 48 Guide ring A Measurement cell

Claims (16)

In a carrier having a coat film having at least a binder resin and particles, the particle diameter (D) of the particles and the film thickness (h) of the coat film have a relationship of 1 <[D / h] <10, The particles are surface-treated with one or more silane coupling agents represented by the following general formula (1) or (2) and having an oxyethylene unit and an alkyl group. Photo carrier.

[However, at least one of X, Y, and Z is halogen or alkoxy (methoxy, ethoxy, etc.). R represents an alkyl group. n is an integer of 0-10. m is an integer of 2 to 20] In a carrier having a coat film having at least a binder resin and particles, the particle diameter (D) of the particles and the film thickness (h) of the coat film have a relationship of 1 <[D / h] <10, The coating film contains one or more silane coupling agents represented by the following general formula (1) or (2) and having an oxyethylene unit and an alkyl group. Career.

[However, at least one of X, Y, and Z is halogen or alkoxy (methoxy, ethoxy, etc.). R represents an alkyl group. n is an integer of 0-10. m is an integer of 2 to 20] In a carrier having a coat film having at least a binder resin and particles, the particle diameter (D) of the particles and the film thickness (h) of the coat film have a relationship of 1 <[D / h] <10, It said particles represented by the following general formula (1) or (2), which is surface treated with one or more silane coupling agent having an oxyethylene unit and an alkyl group, the coating film is represented by the following general formula (1) or (2), electrophotographic carrier which is characterized in that it contains one or more silane coupling agent having an oxyethylene unit and an alkyl group.

[However, at least one of X, Y, and Z is halogen or alkoxy (methoxy, ethoxy, etc.). R represents an alkyl group. n is an integer of 0-10. m is an integer of 2 to 20]
The electrophotographic carrier according to claim 1, wherein the resistivity of the particles is 10 ¹² (Ω · cm) or more and 10 ¹⁶ (Ω · cm) or less.   The electrophotographic carrier according to claim 1, wherein the particles are alumina and / or silica.   6. The electrophotographic carrier according to claim 1, wherein the content of the particles is 40 to 95 wt% of the coating film composition component.   The electrophotographic carrier according to claim 1, wherein the binder resin has a thickness of 0.05 μm to 1.00 μm.   The carrier for electrophotography according to any one of claims 1 to 7, wherein the binder resin contains at least a resin obtained by cross-linking an acrylic resin and an amino resin or / and a silicon resin. .   An electrophotographic developer comprising: a toner comprising at least a binder resin and a pigment; and the electrophotographic carrier according to claim 1.   The electrophotographic developer according to claim 9, wherein the toner contains a release agent.   11. An image forming method using the electrophotographic developer according to claim 9.   A multicolor image forming method using the electrophotographic developer according to claim 9.   11. A developer storage container in which the electrophotographic developer according to claim 9 or 10 is stored.   An image forming apparatus comprising the developer storage container according to claim 13.   An image forming apparatus using the electrophotographic developer according to claim 9.   A process cartridge using the electrophotographic developer according to claim 9 or 10.

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