JP2006018129A - Carrier, and developer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier free of wear of its surface in a development unit, causing no toner spent, capable of stably maintaining charge stability over a prolonged period of time, capable of obtaining clear images, capable of improving the durability of the development unit, and superior longer operating lifetime and resource-saving properties, and to provide a developer that uses the carrier. <P>SOLUTION: The developer comprises the carrier comprising a core which becomes a central material, a covering layer formed on a core surface and a plurality of protrusions formed on the surface of the covering layer, and a toner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a carrier for a two-component developer used in an image forming apparatus and a developer using the carrier. More specifically, the carrier has a coating layer formed on the surface, and the toner hardly adheres to the surface and has excellent wear resistance. And a developer using the same.

  In an image forming apparatus, a magnetic brush developing method using a two-component developer composed of a toner and a carrier is known as a method for adhering toner particles to a photoreceptor on which an electrostatic latent image is formed by electrostatic force. .

  In the developing method using a two-component developer, toner particles and carrier particles are stirred by a stirrer inside the developing device, and the surface of each particle is charged to the opposite polarity by friction, and the generated charge is retained. Is in a state. At the time of development, a developer, which is a mixture of toner and carrier, is conveyed to the vicinity of the photosensitive member holding the electrostatic latent image, and the charged toner is attracted to the surface of the photosensitive member by the electrostatic force of the electrostatic latent image. On the other hand, the carrier used for the development is again collected inside the developing device and re-stirred to contribute to the countering of the toner.

  An example of a conventional image forming apparatus will be described with reference to the drawings. FIG. 3 is a cross-sectional view of a main part showing a conventional image forming apparatus. In FIG. 3, 101 is a conventional image forming apparatus such as an electrostatic copying machine or a laser beam printer, and 102 is an image containing a developer (not shown) that is a mixture of a toner and a carrier that has been frictionally charged in advance. A developing device of the forming apparatus 101, a developer stirring roller 103 that stirs the developer during development, and a developer layer 104 that is disposed at a predetermined interval from the magnet roller 105 and adjusts the supply amount of the developer passing through the gap. A forming blade 106 is a photosensitive belt on which an electrostatic latent image has been formed in advance and is disposed opposite to the magnet roller 105.

  The developing method of the conventional image forming apparatus configured as described above will be described below. The developer accommodated in the developing device 102 is agitated by the developer agitation roller 103 during development and is conveyed to the magnet roller 105. As the magnet roller 105 rotates in the direction of the arrow, the developer passes through the gap between the developer layer forming blade 104 and the magnet roller 105 and approaches the photosensitive belt 106 as the magnet roller 105 rotates. When the developer on the surface of the magnet roller 105 approaches the photosensitive belt 106, the photosensitive belt 106 rotates in the direction of the arrow, so that toner contained in the developer is formed on the surface of the photosensitive belt 106. The electrostatic latent image is attracted by static electricity, cuts off the attraction force due to static electricity with the carrier, and adheres to the electrostatic latent image on the surface of the photoreceptor belt 106.

  Next, a conventional developer will be described with reference to the drawings. FIG. 4A is an enlarged schematic cross-sectional view showing a conventional developer, and FIG. 4B is an enlarged schematic cross-sectional view of a C portion in FIG. In FIG. 4, 110 is a conventional two-component developer, 111 is a carrier of the developer 110, 112 is a core to be a core material of the carrier 111, 113 is a surface layer material of the carrier 111 formed on the surface of the core 112, Reference numeral 113 a denotes a surface of the surface layer material 113, and 114 denotes toner of the developer 110 attracted around the carrier 111 by static electricity.

In general, the carrier 111 of the two-component developer 110 has a surface layer material 113 on the surface of a core 112 made of a metal oxide such as magnetite or ferrite for the purpose of providing triboelectric stability and durability. It is covered. However, as the toner 114 and the carrier 111 are agitated and repeatedly collide with each other in the developing unit 102 over a long period of time, the state of the surface 113a of the surface layer material 113 of the carrier 111 changes, and image degradation occurs. Specifically, the surface layer material 113 of the carrier 111 is worn away from the surface 113a, and the surface of the core 112 is exposed, so that the chargeability to the toner 114 is deteriorated and a clear image cannot be obtained, The resin, filler, additive, or the like, which is a component constituting the toner 114, adheres to the surface of the carrier 111. So-called toner spent deteriorates the chargeability of the toner 114, and a clear image cannot be obtained. As a result of the simultaneous wear of the surface layer material 113 on the surface of the carrier 111 and the toner spent, a phenomenon leading to the lifetime of the developer 110 has occurred. Therefore, in order to solve these problems, the coating material used as the surface layer material 113 is based on a resin such as an acrylic resin or a silicone resin in order to improve charging stability and durability as the carrier 111. In addition, various fillers and additives are added. For example, (Patent Document 1) discloses a coating agent for an electrophotographic carrier based on a modified resin and a carrier using the same. Further, (Patent Document 2) discloses an electrophotographic carrier in which the triboelectric stability and durability of the resin coat layer are improved by the resin structure at the time of curing, and a developer using the same.
JP-A-5-224466 JP-A-6-118724

  However, the above conventional techniques have the following problems.

  (1) (Patent Document 1) and (Patent Document 2) improve the charging stability and durability as a carrier. However, in recent years, the image quality has been further stabilized for a long period of time, and the cost of the developing device has been improved. The demand for down could not be satisfied, and there was a problem that the long life of the carrier was lacking.

  In particular, when used continuously for a long period of time, the carrier surface deteriorates with time, the chargeability with the toner cannot be kept stable, and the image quality deteriorates.

  The present invention solves the above-described conventional problems, and does not cause the carrier surface to wear or cause toner spent in the developing device, and can reliably maintain charging stability for a long period of time. Providing a carrier with excellent performance, and providing a developer that can obtain a clear image using the carrier, can improve the durability of the developing device, and has long life and resource saving. Objective.

  In order to solve the above problems, a carrier according to the present invention includes a core serving as a core, a coating layer formed on the core surface, and a plurality of convex portions formed on the surface of the coating layer. have.

  As a result, when the toner and the carrier are mixed and stirred inside the developing device, the toner comes into contact with the convex portion of the carrier surface, so that the contact area between the toner and the carrier can be reduced, and the coating layer of the carrier is worn. The toner spent can be improved, and a carrier having excellent long-term stability and reliability can be provided.

  In order to solve the above problems, the developer of the present invention includes a core that is a core material, a coating layer formed on the surface of the core, and a plurality of convex portions formed on the surface of the coating layer. And a toner.

As a result, when the toner and the carrier are mixed and stirred inside the developing device, the toner comes into contact with the convex portion of the carrier surface, so that the contact area between the toner and the carrier can be reduced, and the coating layer of the carrier is worn. Development that can improve toner spent, can provide stable images even after long-term development, and can improve the durability of the developing device. An agent can be provided.

  As described above, according to the carrier of the present invention and the developer using the carrier, the following advantageous effects can be obtained.

According to the invention of claim 1,
(1) By providing a plurality of convex portions on the surface of the carrier coating layer, the contact area where the toner and the carrier coating layer are in direct contact with each other can be reduced, and wear of the carrier coating layer and toner spent can be reduced. A carrier having excellent durability that can be improved can be provided.

According to invention of Claim 2, in addition to the effect of Claim 1,
(1) By covering the core surface of the carrier with a coating layer containing a silicone resin, the releasability of the carrier surface can be improved, the adhesion of the toner can be reduced, and toner spent on the carrier surface can be generated. A highly reliable carrier that can be prevented can be provided.

  (2) Since the coating layer contains a conductive material, the conductivity of the coating layer of the carrier can be adjusted, and the toner can be charged to a predetermined charge amount in frictional charging with the toner, which is excellent in practicality. A carrier can be provided.

According to invention of Claim 3, in addition to the effect of Claim 2,
(1) Since the conductive material is carbon black, the carrier coating layer can be provided with appropriate conductivity, and the coating layer has a smooth surface by having an average particle diameter of 0.05 μm to 5 μm. Can be formed on the surface of the coating layer, and can be formed by holding the convex forming material on the surface of the coating layer, so that the wear of the coating layer of carrier particles and the toner spent can be improved. An excellent carrier can be provided.

According to invention of Claim 4, in addition to the effect of Claim 2 or 3,
(1) By containing 5 to 15 parts by weight of a conductive material with respect to 100 parts by weight of the silicone resin, a coating layer having a uniform thickness can be formed, and the toner has a suitable chargeability. A carrier with excellent productivity and reliability can be provided.

According to the invention described in claim 5, in addition to the effect of any one of claims 2 to 4,
(1) By including 5 to 20 parts by weight of the convex portion forming material with respect to 100 parts by weight of the silicone resin, a coating layer with a uniform thickness can be formed and sufficient for the surface of the coating layer It is possible to provide a carrier having excellent durability and reliability, which can form a large number of convex portions and can effectively improve the wear of the coating layer of the carrier and the toner spent.

According to invention of Claim 6, in addition to the effect of any one of Claims 1 to 5,
(1) Since the convex portion has a surface shape formed in a substantially spherical shape, the shape of the convex portion is stabilized, the contact area between the surface of the carrier coating layer and the toner can be reduced, and the carrier coating It is possible to provide a carrier having excellent durability and reliability capable of improving layer wear and toner spent.

According to the invention described in claim 7, in addition to the effect of any one of claims 2 to 6,
(1) The convex portion forming material is formed on the coating layer formed on the surface of the carrier because the convex portion forming material is a spherical particle having a sphericity of 90% to 99% and an average particle size of 1.5 μm to 10 μm. It is possible to form a plurality of spherical protrusions by simply mixing the toner, which is excellent in productivity and can more reliably prevent direct contact between the toner and the carrier coating layer when mixing and stirring with the toner. Further, it is possible to provide a carrier excellent in durability and low cost that can improve wear of the coating layer of the carrier and toner spent.

According to invention of Claim 8, in addition to the effect of any one of Claims 1 to 7,
(1) Since the coating layer has a surface roughness Rz of 2 μm to 10 μm, the convex forming material can be protruded and held on the surface of the coating layer, and a plurality of smooth convex portions are provided on the coating layer. Therefore, it is possible to reliably prevent the toner and the carrier coating layer from coming into direct contact with each other, improve the wear of the carrier coating layer and the toner spent, and provide a carrier having excellent durability.

According to the invention of claim 9,
(1) By providing a plurality of smooth convex portions on the carrier coating layer and providing an appropriate surface roughness, the contact area between the toner and the carrier coating layer can be reduced, and the carrier coating It can maintain stable chargeability for a long time without causing layer wear or toner spent changes in chargeability, and can stably obtain a clear image even when developing over a long period of time. In addition, it is possible to provide a high-quality, long-life developer and excellent resource-saving developer that can improve the durability of the developing device.

  The present invention provides a highly reliable carrier that can stably maintain charging stability for a long period of time without causing the carrier surface to be worn out or causing toner spent inside the developing device. The object was realized by forming a plurality of convex portions on the surface of the coating layer formed on the core surface of the carrier.

  The present invention does not cause changes in chargeability due to wear of the carrier coating layer or toner spent, and can maintain stable chargeability for a long period of time. A coating formed on the core surface of the carrier for the purpose of providing a developer that can stably obtain a clear image and can improve the durability of the developing device and has a long life and resource saving. This was realized by forming a plurality of convex portions on the surface of the layer and reducing the contact area between the toner and the carrier coating layer.

  A first invention made to solve the above problems is a carrier, which is a core as a core, a coating layer formed on the surface of the core, and a plurality of protrusions formed on the surface of the coating layer. And a configuration having a portion.

  This configuration has the following effects.

  (1) Since a coating layer is formed on the surface of the core serving as the core material of the carrier, and a plurality of convex portions are formed on the surface of the coating layer, the toner and the carrier are mixed when the toner and the carrier are mixed and stirred inside the developing device. The contact area with which the coating layer directly contacts can be reduced, wear of the coating layer of the carrier and toner spent can be improved, and a stable image can be obtained for a long period of time.

  Here, conventionally known cores can be used as the core of the carrier. For example, ferromagnetic metals such as iron, cobalt and nickel, and metal oxides such as magnetite and ferrite are suitable. Used for. The particle diameter of these cores is usually 30 μm to 300 μm.

Synthetic resins such as acrylic resin, urethane resin, and fluororesin are preferably used as the main component for forming the coating layer, but the releasability of the surface of the coating layer is particularly good when the coating layer is formed. Is inexpensive, it is desirable to use silicone resin.

  The convex part formed on the surface of the coating layer may be formed in advance by forming a convex part on the core that becomes the core material of the carrier, and may be covered with the coating layer. It may be formed by filling a spherical filler or the like. By forming the surface of the convex portion smoothly, damage due to contact with the toner can be reduced, and the durability is excellent.

  2nd invention made | formed in order to solve the said subject is a carrier as described in 1st invention, Comprising: The said coating layer composition contains a silicone resin, a electrically conductive material, and a convex part formation material. It has the composition to do.

  With this configuration, in addition to the operation of the first invention, the following operation is provided.

  (1) By covering the core surface of the carrier with a coating layer containing a silicone resin, the releasability of the carrier surface can be improved, the adhesion of toner can be reduced, and the toner spent on the carrier surface can be reduced. Can be prevented.

  (2) When the coating layer contains a conductive material, the conductivity of the coating layer of the carrier can be adjusted, and the toner can be charged to a predetermined charge amount during frictional charging with the toner, improving the image quality. Can be made.

  Here, examples of the silicone resin include KR155, KR155, KR201, KR261, KR271, KR280, KR285, KR350 manufactured by Shin-Etsu Silicone, SR2100, SR2101, SR2400, SR2401, SR24010, SR2411 manufactured by Toray Dow Corning Silicone. Commercial products such as these can be used.

  As the conductive material, conventionally known carbon black, carbon fiber, metal powder and the like are preferably used.

  Examples of the convex forming material include resin powders such as silicone rubber powder, nylon powder, and acrylic powder formed in a substantially spherical shape, metal powders such as iron, copper, and aluminum, and ceramic powders such as alumina, silica, and zirconia. Preferably used.

  These need to be properly used depending on the type of the synthetic resin constituting the carrier coating layer. In other words, if the convex portion forming material has poor wettability with respect to the synthetic resin, it cannot be uniformly dispersed in the synthetic resin and a smooth convex portion cannot be formed on the carrier surface. In addition, if the specific gravity of the convex portion forming material is too large compared to the synthetic resin, the convex portion forming material will settle to the bottom of the coating layer when the coating layer is formed, and if the specific gravity of the convex portion forming material is too small, At the time of layer formation, the convex portion forming material floats on the surface of the coating layer, and none of them can form a smooth convex portion on the carrier surface.

  Next, the manufacturing method of the coating layer composition of a carrier is demonstrated. The silicone resin is taken in a hard resin container, and then the conductive material is weighed and charged. Further, a dispersion medium such as zirconia spherical particles is introduced. The container is sealed and dispersed for a predetermined time on a ball mill mount. The dispersion is sampled and the carbon dispersion state is evaluated using a particle gauge. Thereafter, a predetermined amount of the convex portion forming material is charged, and further dispersed and discharged for a predetermined time with a ball mill frame. In order to adjust the viscosity of the dispersion, an appropriate amount of an organic solvent such as toluene is prepared and stirred to obtain a coating layer composition solution.

Next, the manufacturing method of a carrier is demonstrated. A core material to be a core material of the carrier is put into a fluidized bed, and the coating layer composition solution is applied by a spray coating method in a state where the core material is fluidized. The input amount of the coating layer composition solution is 0.7% by weight with respect to the carrier weight. At the time of spray coating, hot air of 80 ° C. is blown into the fluidized bed to dry the surface of the composition coated on the core surface. Thereafter, the core coated with the coating layer composition solution is taken on a stainless steel vat and dried at 200 ° C. for 3 hours to obtain a carrier.

  A third invention made to solve the above problems is the carrier according to the second invention, wherein the conductive material is carbon black having an average particle diameter of 0.05 μm to 5 μm. is doing.

  With this configuration, in addition to the operation of the second invention, the following operation is provided.

  (1) Since the conductive material is carbon black, the carrier coating layer can be provided with appropriate conductivity, and the coating layer has a smooth surface by having an average particle diameter of 0.05 μm to 5 μm. The convex portion can be formed by holding the convex portion forming material on the surface of the coating layer, and the wear of the coating layer of the carrier and the toner spent can be improved.

  Here, examples of carbon black include furnace black, thermal black, and ketjen black. The carbon contained in the coating layer composition is preferably dispersed in an average particle size of 0.05 μm to 5 μm. As the average particle size of carbon becomes smaller than 0.05 μm, processing and handling tend to become difficult, and as the particle size becomes larger than 5 μm, unevenness occurs on the surface of the coating layer due to the carbon particles located near the surface of the coating layer. However, it tends to cause toner spent on the carrier surface during mixing and stirring with the toner, and the chargeability tends to deteriorate, both of which are not preferable. By making the average particle diameter of carbon dispersed in the coating layer of the carrier 5 μm or less, the carbon particles located near the surface of the coating layer can give a smooth shape without roughening the surface of the coating layer. .

  4th invention made | formed in order to solve the said subject is a carrier of any one of 2nd or 3rd invention, Comprising: The said electrically-conductive material is 5 with respect to 100 weight part of said silicone resins. It has the structure contained by weight part-15 weight part.

  With this configuration, in addition to the operation of any one of the second and third inventions, the following operation is provided.

  (1) By containing 5 to 15 parts by weight of a conductive material with respect to 100 parts by weight of the silicone resin, a coating layer having a uniform thickness can be formed, and the toner has a suitable chargeability. The image quality can be improved.

  Here, as the amount of the conductive material becomes less than 5 parts by weight with respect to 100 parts by weight of the silicone resin, the conductivity of the coating layer of the carrier becomes lower than a predetermined value, and a suitable charging property is given to the toner. As the amount exceeds 20 parts by weight, the conductivity of the carrier coating layer becomes higher than a predetermined value, and it becomes impossible to give suitable chargeability to the toner. When the composition is coated on the core surface of the carrier, the fluidity of the composition tends to be lowered, and a coating layer having a uniform thickness tends not to be obtained.

  A fifth invention made to solve the above problems is the carrier according to any one of the second to fourth inventions, wherein the convex portion forming material is used with respect to 100 parts by weight of the silicone resin. Is included in an amount of 5 to 20 parts by weight.

  With this configuration, in addition to the operation of any one of the second to fourth inventions, the following operation is provided.

  (1) By including 5 to 20 parts by weight of the convex portion forming material with respect to 100 parts by weight of the silicone resin, a coating layer with a uniform thickness can be formed and sufficient for the surface of the coating layer A large number of convex portions can be formed, wear of the carrier coating layer and toner spent can be effectively improved, and durability can be improved.

  Here, as the convex portion forming material becomes less than 5 parts by weight with respect to 100 parts by weight of the silicone resin, a sufficient number of convex portions cannot be formed on the surface of the coating layer, and during mixing and stirring with the toner, The toner surface tends to be easily generated on the carrier surface, and the chargeability tends to deteriorate. As the amount exceeds 20 parts by weight, the viscosity of the coating layer composition increases, and the composition is formed when the core surface is coated with the composition. There is a tendency that the fluidity of the product tends to be lowered and a coating layer having a uniform thickness cannot be obtained, both of which are not preferable.

  A sixth invention made to solve the above problem is the carrier according to any one of the first to fifth inventions, wherein the convex portion is formed in a substantially hemispherical surface. It has a configuration with a shape.

  With this configuration, in addition to the operation of any one of the first to fifth inventions, the following operation is provided.

  (1) Since the convex portion has a surface shape formed in a substantially hemispherical shape, the shape of the convex portion is stabilized, and wear of the carrier coating layer and generation of toner spent are prevented over a long period of time. And durability can be improved.

  7th invention made | formed in order to solve the said subject is a carrier of any one of 2nd thru | or 6th invention, Comprising: The said convex-part formation material is 90% of sphericity 90-99. %, Spherical particles formed to have an average particle diameter of 1.5 μm to 10 μm.

  With this configuration, in addition to the operation of any one of the second to sixth inventions, the following operation is provided.

  (1) The convex portion forming material is formed on the coating layer formed on the surface of the carrier because the convex portion forming material is a spherical particle having a sphericity of 90% to 99% and an average particle size of 1.5 μm to 10 μm. A plurality of hemispherical projections can be formed simply by mixing the toner, and it is possible to more reliably prevent the toner and the carrier coating layer from directly contacting each other when mixing and stirring with the toner.

  Here, the sphericity (%) of the spherical particles is {1- (AB) / ((A + B) / 2)} × 100, where A is the major axis of the target particle and B is the minor axis. (%) The measurement is performed by taking an optical microscope or electron micrograph of the target particle and measuring the diameter of the photographed particle.

  As the sphericity of the spherical particles as the convex forming material becomes smaller than 90%, the difference between the major axis and the minor axis becomes too large to form the convex part into a spherical shape. The toner surface tends to cause toner spent, and the chargeability tends to deteriorate. As it exceeds 99%, the yield tends to decrease and the productivity tends to be poor.

  As the average particle diameter of the spherical particles that are the convex portion forming material becomes smaller than 1.5 μm, the convex portion forming material is buried in the coating layer and hardly protrudes to the surface, making it difficult to form a spherical convex portion. As the size exceeds 10 μm, when the carrier and toner are mixed and stirred, the toner easily adheres between the convex portions formed on the surface of the coating layer of the carrier, and the toner spent on the carrier surface. Is generated, and the chargeability tends to be deteriorated.

  An eighth invention made to solve the above problems is the carrier according to any one of the first to seventh inventions, wherein the coating layer has a surface roughness Rz of 2 μm to 10 μm. It has the composition which is provided.

  With this configuration, in addition to the operation of any one of the first to seventh inventions, the following operation is provided.

  (1) Since the coating layer has a surface roughness Rz of 2 μm to 10 μm, the coating layer can be uniformly formed, and the convex forming material can be protruded and held on the surface of the coating layer, A plurality of smooth convex portions can be provided on the coating layer, so that direct contact between the toner and the carrier coating layer can be reliably prevented, and a stable charging property can be obtained.

  Here, the surface roughness Rz is a surface roughness evaluation standard described in JIS handbook 34 metal surface treatment, and in the portion extracted by a reference length from a cross-sectional curve obtained by a surface roughness meter such as a contact type, an average is obtained. The value of the difference between the average value of the highest altitude at the top of the 5th peak and the average value of the altitude at the bottom of the valley from the deepest to the fifth measured in the direction of the vertical magnification from a straight line that is parallel to the line and does not cross the section curve Is expressed in micrometers.

  As the surface roughness Rz of the coating layer becomes smaller than 2 μm, the yield tends to decrease and the productivity tends to be lacking. As the surface roughness becomes larger than 10 μm, the convex portion is lost in the roughness of the surface of the coating layer. It tends to be difficult to form a hemispherical convex portion, which is not preferable.

  A ninth invention made to solve the above problems is a developer, comprising a carrier according to any one of claims 1 to 8 and a toner. Yes.

  This configuration has the following effects.

  (1) By providing a plurality of smooth convex portions on the carrier coating layer and providing an appropriate surface roughness, the contact area between the toner and the carrier coating layer can be reduced, and the carrier coating It does not cause changes in chargeability due to layer wear or toner spent, can maintain stable chargeability for a long period of time, can improve the durability of the developing device, and when developed over a long period of time In addition, a clear image can be stably obtained.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is an enlarged schematic cross-sectional view showing a carrier according to Embodiment 1 of the present invention, and FIG. 1B is an enlarged schematic cross-sectional view of part A in FIG.

In FIG. 1, 11 is a carrier in Embodiment 1 of the present invention, 12 is a ferromagnetic metal such as iron, cobalt, nickel, or a metal oxide such as magnetite or ferrite, and has a substantially spherical shape with a particle size of 30 μm to 300 μm. The core as a core material of the formed carrier 11, 13 is a coating layer of the carrier 11 formed on the surface of the core 12, and 13 a has a substantially hemispherical surface shape that is formed in a plurality so as to protrude from the surface of the coating layer 13. It is a convex part.

  The coating layer 13 is 5 parts by weight to 15 parts by weight of carbon black having an average particle diameter of 0.05 μm to 5 μm, which is a conductive material, and 90% of the sphericity, which is a convex part forming material, with respect to 100 parts by weight of the silicone resin. 99%, resin powder such as silicone rubber powder, nylon powder, acrylic powder, etc. formed to an average particle size of 1.5 μm to 10 μm, metal powder such as iron, copper, aluminum, etc., and ceramic powder such as alumina, silica, zirconia, etc. Were formed by a coating layer composition containing 5 to 20 parts by weight of spherical particles.

  By using a silicone resin as the resin component of the coating layer 13, the surface of the coating layer 13 has good releasability and excellent productivity and low cost.

  As the amount of the conductive material becomes less than 5 parts by weight with respect to 100 parts by weight of the silicone resin, the conductivity of the coating layer 13 of the carrier 11 becomes lower than a predetermined value, and a suitable charging property can be given to the toner. As the amount exceeds 20 parts by weight, the conductivity of the coating layer 13 of the carrier 11 becomes higher than a predetermined value, and it becomes impossible to give suitable chargeability to the toner. It can be seen that the viscosity of the product is increased, and when the composition is coated on the surface of the core 12 of the carrier 11, the fluidity of the composition tends to decrease, and the coating layer 13 having a uniform thickness tends not to be obtained. It was.

  Further, as the average particle diameter of carbon of the carbon black, which is a conductive material, becomes smaller than 0.05 μm, it becomes difficult to process and handle, resulting in poor productivity. It was found that the carbon particles cause irregularities on the surface of the coating layer 13 and easily cause toner spent on the surface of the carrier 11 during mixing and stirring with the toner, resulting in poor chargeability.

  By setting the average particle size of carbon dispersed in the coating layer 13 of the carrier 11 to 5 μm or less, the carbon particles located near the surface of the coating layer 13 do not roughen the surface of the coating layer 13 and have a smooth shape. I found out that

  As the convex forming material becomes less than 5 parts by weight with respect to 100 parts by weight of the silicone resin, a sufficient number of convex parts 13a cannot be formed on the surface of the coating layer 13, and the carrier is mixed during stirring with the toner. The surface of the toner 11 tends to generate toner spent and the chargeability tends to deteriorate. As the amount exceeds 20 parts by weight, the viscosity of the coating layer composition of the carrier 11 increases, and the surface of the core 12 is coated with the composition. At this time, it was found that the fluidity of the composition tends to decrease, and the coating layer 13 having a uniform thickness tends not to be obtained.

  Further, as the sphericity of the spherical particles as the convex portion forming material becomes smaller than 90%, the difference between the major axis and the minor axis becomes too large to form the convex portion 13a into a hemispherical shape, and the toner and During mixing and stirring, it was found that the toner spent on the surface of the carrier 12 tends to be caused and the chargeability tends to deteriorate, and as it exceeds 99%, the yield tends to decrease and the productivity tends to be lacking.

  As the average particle diameter of the spherical particles as the convex portion forming material becomes smaller than 1.5 μm, the convex portion forming material is buried in the coating layer 13 and hardly protrudes to the surface, and the spherical convex portion 13a can be formed. There is a tendency to become difficult, and as it becomes larger than 10 μm, when the carrier 11 and the toner are mixed and stirred, the toner easily adheres between the convex portions 13 a formed on the surface of the coating layer 13 of the carrier 11. It has been found that toner spent is generated on the surface and the chargeability tends to deteriorate.

  The surface roughness Rz of the coating layer was 2 μm to 10 μm. As the surface roughness Rz of the coating layer 13 becomes smaller than 2 μm, the yield tends to decrease and the productivity tends to be lacking, and as the surface roughness Rz becomes larger than 10 μm, the convex portion 13a is included in the surface roughness of the coating layer 13. It turns out that it tends to be difficult to form an independent spherical convex portion 13a.

  The developer using the carrier according to the first embodiment formed as described above will be described below with reference to the drawings.

  FIG. 2A is an enlarged schematic cross-sectional view showing a developer using a carrier in Embodiment 1 of the present invention, and FIG. 2B is an enlarged schematic cross-sectional view of a B part in FIG.

  In FIG. 2, 14 is a toner attracted around the carrier 11 by static electricity, and 20 is a two-component developer using the carrier 11 according to Embodiment 1 of the present invention.

  When the toner 14 and the carrier 11 are mixed and stirred inside the developing device, the toner 14 comes into contact with the convex portion 14 on the surface of the carrier 11, so that the toner 14 can be prevented from coming into direct contact with the coating layer 13 of the carrier 11, Wear of the coating layer 13 of the carrier 11 can be reduced, and generation of toner spent can be suppressed.

  As described above, the carrier and the developer using the carrier according to the first embodiment of the present invention are configured, and thus have the following effects.

  (1) Since the coating layer 13 is formed on the surface of the core 12 serving as the core material of the carrier 11 and a plurality of convex portions 13a are formed on the surface of the coating layer 13, the toner 14 and the carrier 11 are mixed and stirred inside the developing device. In this case, the contact area where the toner 14 and the coating layer 13 of the carrier 11 are in direct contact with each other can be reduced, wear of the coating layer 13 of the carrier 11 and toner spent can be improved, and stable for a long period of time. An image can be obtained.

  (2) By covering the surface of the core 12 of the carrier 11 with the coating layer 13 containing the silicone resin, the releasability of the surface of the carrier 11 can be improved and the adhesion of the toner 14 can be reduced. Further, toner spent on the surface of the carrier 11 can be prevented.

  (3) Since the coating layer 13 includes a conductive material, the conductivity of the coating layer 13 of the carrier 11 can be adjusted, and the toner 14 can be charged to a predetermined charge amount in frictional charging with the toner 14. , Image quality can be improved.

  (4) When the conductive material is carbon black, it is possible to impart appropriate conductivity to the coating layer 13 of the carrier 11, and the average particle size of 0.05 μm to 5 μm allows the coating layer 13 to The surface can be formed smoothly, the convex portion 13a can be formed by holding the convex portion forming material on the surface of the coating layer 13, and the wear of the coating layer 13 of the carrier 11 and the toner spent can be improved. it can.

  (5) By containing 5 parts by weight to 15 parts by weight of the conductive material with respect to 100 parts by weight of the silicone resin, the coating layer 13 having a uniform thickness can be formed, and the toner 14 can be charged appropriately. The image quality can be improved.

(6) The convex layer forming material is included in an amount of 5 to 20 parts by weight with respect to 100 parts by weight of the silicone resin, whereby the coating layer 13 having a uniform thickness can be formed and the surface of the coating layer 13 A sufficient number of convex portions 13a can be formed, wear of the coating layer 13 of the carrier 11 and toner spent can be effectively improved, and durability can be improved.

  (7) Since the convex portion 13a has a surface shape formed in a substantially hemispherical shape, the shape of the convex portion 13a is stabilized, and wear of the coating layer 13 of the carrier 11 and generation of toner spent over a long period of time. Can be prevented, and durability can be improved.

  (8) Since the convex portion forming material is a spherical particle having a sphericity of 90% to 99% and an average particle size of 1.5 μm to 10 μm, the convex portion is formed on the coating layer 13 formed on the surface of the carrier 11. A plurality of spherical convex portions 13a can be formed simply by mixing the forming material, and the toner 14 and the coating layer 13 of the carrier 11 are more reliably prevented from coming into direct contact with the toner 14 when mixed and stirred. be able to.

  (9) Since the coating layer 13 has a surface roughness Rz of 2 μm to 10 μm, the coating layer 13 can be formed uniformly, and a convex forming material is protruded and held on the surface of the coating layer 13. The coating layer 13 can be provided with a plurality of smooth convex portions 13a, and the toner 14 and the coating layer 13a of the carrier 11 can be reliably prevented from coming into direct contact with each other, and a stable charging property can be obtained. it can.

  (10) Use a developer 20 in which a plurality of smooth convex portions 13a are provided on the coating layer 13 of the carrier 11 and the contact area between the toner 14 and the coating layer 13 is reduced by giving an appropriate surface roughness. Therefore, it is possible to maintain a stable chargeability for a long period of time without causing wear of the coating layer 13 of the carrier 11 or a change in chargeability due to toner spent, and to improve the durability of the developing device. Even when development is performed over a wide range, a clear image can be stably obtained, and resource saving is excellent.

  Examples of the present invention will be described below.

  First, a method for producing a carrier coating layer composition will be described.

  As a resin component of the composition for forming the coating layer, 500 g of silicone resin SR-2411 (solid content 20%) (resin component 100 g) manufactured by Toray Dow Corning Silicone Co., Ltd. is placed in a 2 L hard resin container, and then conductive A predetermined amount (see (Table 2) and (Table 3)) of a medium thermal carbon manufactured by Huber was weighed and added as a material. Furthermore, 500 cc cups were charged using φ5 mm zirconia spherical particles as dispersion media. Thereafter, the container was sealed and dispersed for a predetermined time on a ball mill mount. The dispersion was sampled, and the carbon dispersion state was evaluated using a particle gauge having a full scale of 25 μm. Thereafter, a predetermined amount (see (Table 2) and (Table 3)) of spherical particles as the convex portion forming material was charged, and further dispersed and discharged for a predetermined time with a ball mill mount. Then, in order to adjust the viscosity of the dispersion, an appropriate amount of toluene, which is an organic solvent, was prepared and stirred to obtain a coating layer composition solution for forming a carrier coating layer.

  Spherical silica with 99% sphericity (Admafine manufactured by Admatech Co., Ltd.), glass beads with 90% sphericity (hollow glass beads manufactured by Toshiba Ballotini Co., Ltd.), irregular shape with 70% sphericity Silica (Silisia manufactured by Fuji Silysia Chemical Co., Ltd.) was used. The characteristics of the convex forming materials C1 to C5 are shown in (Table 1).

  Next, the method for producing the carrier of the present invention will be described.

  A commercially available ferrite carrier (FL-150T, manufactured by Powdertech Co., Ltd.) was used as the core material to be the core material of the carrier. 2 kg of the core material was charged into the fluidized bed, and the coating layer composition solution was applied by a spray coating method with the core material flowing. The input amount of the composition was 0.7% by weight with respect to the carrier weight. Moreover, at the time of spray coating, warm air of 80 ° C. was blown into the fluidized bed to dry the surface of the composition coated on the carrier surface. Thereafter, the core material coated with the composition was placed on a stainless steel vat and dried at 200 ° C. for 3 hours to obtain a carrier.

  A developability test was performed using the carrier thus prepared.

  As the developer used in the test, the above-mentioned carrier and our toner (product number FCS1970) were blended, and the blending ratio was 5%. 600 g of this developer was weighed out in a developing device, and mounted on a printer WORKIO DP-3010 manufactured by our company, and a developability test was performed.

  The evaluation items performed in the developability test were evaluation of initial and initial charge amounts and fog after printing 120,000 sheets, and wear of the carrier coating layer by electron microscope observation. The charge amount was evaluated using a blow-off friction charge measuring device (manufactured by Toshiba Chemical Corporation).

  9.5 g of carrier and 0.5 g of toner are placed in a 100 ml polyethylene container, and this container is rotated on a rotating table at a speed of 300 revolutions per minute for 5 minutes. Thereafter, about 1 g of the carrier / toner mixture is taken out. This was applied to a blow-off triboelectric charge measuring device, and the measured charge amount converted to 1 g of toner was taken as the charge amount.

  About fog, the absolute density of fog generated on a white background portion of the paper was measured with a white meter using a white meter MODELZ-1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.).

  The developability test results of Examples and Comparative Examples will be described below.

  The coating layer compositions and properties of the carriers used in the examples and comparative examples, and the evaluation results are shown in (Table 2) and (Table 3).

  Example 1 A coating layer composition was prepared using a silicone resin, a conductive material, and a convex portion forming material C1. The average particle diameter of the spherical particles contained in the prepared composition is 1.5 μm, the sphericity is 99%, the change in charge amount and fog after printing 120,000 sheets is small, and the surface of the coating layer The condition was also good.

(Example 2) A coating layer composition was prepared using a silicone resin, a conductive material and a convex portion forming material C3. The spherical particles contained in the prepared composition have an average particle size of 10 μm, a sphericity of 90%, little change in charge amount and fog after printing 120,000 sheets, and the surface state of the coating layer is also It was good.

  (Example 3) A coating layer composition was prepared using a silicone resin, a conductive material and a convex portion forming material C1. The average particle diameter of the spherical particles contained in the prepared composition is 1.5 μm, the sphericity is 99%, the change in charge amount and fog after printing 120,000 sheets is small, and the surface of the coating layer The condition was also good.

  (Example 4) A coating layer composition was prepared using a silicone resin, a conductive material, and a convex portion forming material C3. The spherical particles contained in the prepared composition have an average particle size of 10 μm, a sphericity of 90%, little change in charge amount and fog after printing 120,000 sheets, and the surface state of the coating layer is also It was good.

  (Comparative example 1) The coating layer composition which does not contain a convex part formation material was produced using the silicone resin and the electrically conductive material. Changes in the numerical values of the charge amount and fog after printing 120,000 sheets were large, and abrasion on the surface of the coating layer was observed. This is because the convex portion was not formed on the surface of the coating layer by not including the convex portion forming material.

  (Comparative Example 2) A coating layer composition was prepared using a silicone resin, a conductive material, and a convex portion forming material C1. When the particle size of the conductive material was too large, the dispersion of the conductive material was insufficient, surface roughness was generated in the coating layer, and a uniform coating layer was not obtained, and the subsequent evaluation was stopped.

  (Comparative example 3) The coating layer composition was produced using the silicone resin, the electrically conductive material, and the convex formation material C2. The average particle size of the spherical particles contained in the prepared composition is 0.3 μm, the sphericity is 99%, the change in charge amount and fog after printing 120,000 sheets is large, Abrasion was observed. This is because the convex portion forming material was buried in the coating layer and the spherical convex portion was not formed because the average particle diameter of the spherical particles of the convex portion forming material was as small as 0.3 μm.

  (Comparative example 4) The coating layer composition was produced using the silicone resin, the electrically conductive material, and the convex formation material C4. The spherical particles contained in the prepared composition have an average particle diameter of 45 μm and a sphericity of 90%. The amount of charge and fog after printing 120,000 sheets are large, and the surface of the coating layer is observed. Then, the traces of toner spent and spherical particles were observed. This is because the average particle diameter of the spherical particles of the convex portion forming material is as large as 45 μm, so that the gap between the convex portions and the convex portions is excessively opened, and the toner easily adheres.

  (Comparative Example 5) A coating layer composition was prepared using a silicone resin, a conductive material, and a convex portion forming material C5. The spherical particles contained in the prepared composition have an average particle size of 1.4 μm, a sphericity of 70%, a large change in charge amount and fog after printing 120,000 sheets, and the surface of the coating layer In this observation, toner spent and wear were observed. This is because the difference between the major axis and the minor axis of the spherical particles becomes too large to form the convex portion in a spherical shape.

  (Comparative example 6) The coating layer composition was produced using the silicone resin, the electrically conductive material, and the convex part formation material C1. The average particle size of the spherical particles contained in the prepared composition is 1.5 μm, the sphericity is 99%, the change in charge amount and fog after printing 120,000 sheets is large, and the surface of the coating layer Wear was observed. This is because the convex portion forming material is 30 parts by weight with respect to 100 parts by weight of the resin component, the viscosity of the coating layer composition increases, and the fluidity of the composition decreases when the composition is coated on the core surface. This is because it was easy to obtain a coating layer having a uniform thickness.

From the above results, according to the carrier of the present invention and the developer using the same, the carrier surface does not wear or cause toner spent inside the developing unit, and is stably charged for a long period of time. It was found that a clear image can be obtained.

  The present invention relates to a carrier for a two-component developer used in an image forming apparatus and a developer using the carrier, and the carrier surface does not wear or cause toner spent in the developing unit and is stable for a long period of time. Providing a carrier with excellent reliability capable of maintaining charging stability and using it, a clear image can be obtained, and the durability of the developing device can be improved. The present invention realizes the provision of a developer having excellent properties, and can satisfy the recent demands for long-term stabilization of image quality and cost reduction of the developing device.

(A) Enlarged schematic cross-sectional view showing the carrier in Embodiment 1 of the present invention, (b) A-part enlarged schematic cross-sectional view in (a) (A) Enlarged schematic cross-sectional view showing a developer using the carrier in Embodiment 1 of the present invention, (b) B-part enlarged schematic cross-sectional view in (a) Cross-sectional view of main parts showing a conventional image forming apparatus (A) Enlarged schematic cross-sectional view showing a conventional developer, (b) C-part enlarged schematic cross-sectional view in (a)

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Carrier 12 Core 13 Cover layer 13a Convex part 14 Toner 20 Developer 101 Conventional image forming apparatus 102 Developer 103 Developer stirring roller 104 Developer layer forming blade 105 Magnet roller 106 Photoreceptor belt 110 Conventional two-component development Agent 111 Carrier 112 Core 113 Surface layer material 113a Surface 114 Toner

Claims (9)

A carrier comprising: a core as a core material; a coating layer formed on the surface of the core; and a plurality of convex portions formed on the surface of the coating layer. The carrier according to claim 1, wherein the coating layer composition contains a silicone resin, a conductive material, and a convex portion forming material. The carrier according to claim 2, wherein the conductive material is carbon black having an average particle diameter of 0.05 μm to 5 μm. The carrier according to claim 2 or 3, wherein the conductive material is contained in an amount of 5 to 15 parts by weight with respect to 100 parts by weight of the silicone resin. 5. The carrier according to claim 2, wherein 5 to 20 parts by weight of the convex forming material is contained with respect to 100 parts by weight of the silicone resin. The carrier according to any one of claims 1 to 5, wherein the convex portion has a surface shape formed in a substantially hemispherical shape. The said convex-part formation material is a spherical particle formed in 90%-99% of sphericity, and an average particle diameter of 1.5 micrometers-10 micrometers, It is any one of the Claims 2 thru | or 6 characterized by the above-mentioned. Career. The carrier according to any one of claims 1 to 7, wherein the coating layer has a surface roughness Rz of 2 µm to 10 µm. A developer comprising the carrier according to any one of claims 1 to 8 and a toner.

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