JP2009282265A - Developing device, image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which does not have the toner scraping properties degrade from a developing roller by a toner supply roller with passage of time, even when using a toner with a form close to a spherical shape. <P>SOLUTION: The image forming apparatus comprises: a developing roller 73, made of an elastic member for visualizing an electrostatic latent image formed on an image carrier, by supplying a single component toner; a toner supply roller 72 for supplying a toner to the developing roller 73; and a doctor blade 74 which is to be contacted with the developing roller 73 for processing the toner layer on the developing roller 73 into a thin layer. When the single component toner particles are projected onto a plane, the average value of the roundness defined by the circumferential length of a circle of the same projection area/the circumferential length of the toner particle is in a range of 0.95-1.0, and the toner supply roller is made of a foaming object, with the density of 150-200 kg/m<SP>3</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device used for a copying machine, a printer, a FAX, and the like and an image forming apparatus including the developing device.

  In recent years, there has been an increasing demand for speeding up the color output of color printers, and the number of image forming apparatuses configured to form a color image by arranging a plurality of color image forming units in parallel has increased. An example of a conventional image forming apparatus is shown in FIG. This image forming apparatus is configured to transfer a color image from the image carrier 500 to the intermediate transfer belt 501 at the primary transfer unit, and to transfer the color image onto the transfer paper at the secondary transfer unit 502. Of course, a configuration in which a color image is directly transferred from the image carrier 500 onto a transfer sheet is also possible. A color printer, which is one of image forming apparatuses, often uses a configuration in which the developing unit 503 and the image carrier unit 511 are integrated so that the user can easily replace the unit. By using a one-component developing device for the developing unit 503, the size and cost of the device can be reduced. By making the developing unit 503 vertically long, a necessary amount of toner can be accommodated, and the machine width in the horizontal width direction in the drawing can be shortened. In FIG. 8, after charging the image carrier 500 with the charging roller 504, it is exposed by a writing optical system (not shown) to form a latent image, and a toner image is formed by a one-component developing device and transferred to the intermediate transfer belt 501. To do. The toner images of the respective colors are superimposed on the intermediate transfer belt 501, transferred to a transfer sheet conveyed by a paper conveyance unit (not shown) in the secondary transfer unit 502, and the toner image is fixed on the transfer sheet by a fixing unit 505. .

  Next, the developing unit 503 will be described. A developing container 506 of the developing unit 503 shown in FIG. 10 contains a predetermined amount of non-magnetic one-component toner T, and the toner is supplied to a toner supply roller 507 made of a foam disposed at the lower part of the developing container. Supplied. The toner supply roller 507 and the developing roller 508 rotate at a predetermined linear speed ratio in the direction of the arrow in the drawing, and supply toner from the toner supply roller 507 to the developing roller 508. The developing roller 508 has elasticity, and has toner transportability by attaching coarse particles to the surface layer or by roughening the surface layer itself. The toner adhering to the developing roller 508 is frictionally charged at the nip portion (doctor nip portion) between the doctor blade 509 that is a toner layer regulating member and the developing roller 508, and becomes negative polarity. The toner that has passed through the nip forms a toner layer having a predetermined thickness on the developing roller 508. Since more toner than necessary is attached to the developing roller 508 before the nip portion, excess toner is blocked by the doctor blade 509 and returns to the toner supply roller 507 side. At this time, if the weight of the toner is applied to the developing roller 508 side, the circulation property of the toner in front of the doctor blade 509 is lowered. For this reason, the developing unit 503 in FIG. 9 is provided with a pressure relief plate 510 for releasing the toner so that the weight of the toner is not applied to the developing roller 508 at the front portion of the doctor blade 509.

  The electrostatic latent image on the image carrier is developed at the developing nip portion by the uniform toner layer on the developing roller 508 after passing through the doctor nip portion. Toner that has not been used for development is scraped off from the developing roller 508 at the nip with the toner supply roller 507. If the scraping effect is small, a development history remains in the toner layer on the developing roller 508, and a history in the previous development remains after passing through the doctor blade, so that an afterimage of the pitch of the developing roller 508 becomes a problem. Further, the toner remaining without being scraped off is strongly adhered to the developing roller 508, and therefore passes again through the doctor blade 509, and the toner in a portion where there is no image remains attached to the developing roller 508, and the toner at the doctor blade 509 is removed. It continues to receive stress and deteriorates, causing blade sticking and developing roller filming.

  Recently, there is a strong demand for higher image quality in a color image forming apparatus using a one-component developing device that is small and suitable for cost reduction. For this reason, in a one-component developing device, it is necessary to reduce the particle size of the toner to improve the image quality. The mainstream is to reduce the particle size of the toner using polymerized toner, and the particle size distribution can be made sharper than that of the pulverized toner. Further, since the polymerized toner is nearly spherical as compared with the pulverized toner, there is an advantage that the transfer rate is increased by optimizing the additive. However, when using a nearly spherical toner in a one-component developing device, it is necessary to improve the toner transportability of the developing roller 508, and it is necessary to roughen the developing roller surface layer. When the surface layer of the developing roller 508 is roughened, there is a problem that the toner scraping property of the toner supply roller 507 is lowered. In particular, the scraping property of the toner tends to be lower with the passage of time than the initial stage.

  As the toner supply roller 507, a sponge roller or a brush roller is used. The sponge roller and the brush roller exhibit different characteristics such as materials, charging characteristics, surface resistance, and load torque, and also have different effects. As an invention in which the brush roller is improved and the scraping performance is maintained over time, the one disclosed in Patent Document 1 is known. In this patent document, the toner gradually enters the sponge due to the contact pressure between the developing roller and the toner supply sponge roller, the sponge is enlarged, the pressure with the developing roller changes, and the driving load torque increases. The effect is described.

JP 2005-189405 A

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that even when toner having a nearly spherical shape is used, the toner scraping property from the developing roller by the toner supply roller does not deteriorate over time. It is an object of the present invention to provide an apparatus and an image forming apparatus including the apparatus.

The features of the present invention, which is a means for solving the above problems, are listed below.
The developing device of the present invention includes a developing roller made of an elastic body that supplies a one-component toner to an electrostatic latent image formed on an image carrier and visualizes the toner, a toner supply roller that supplies toner to the developing roller, In an image forming apparatus having a toner layer regulating member that is in contact with the developing roller and has a toner layer on the developing roller as a thin layer, when one-component toner particles are projected onto a plane, the circumference of an equivalent circle having the same projected area The average value of the circularity defined by the length / perimeter of the toner particles is in the range of 0.95 to 1.0, the toner supply roller is made of a foam, and the density of the foam is 150 to 200 kg / m. It is ³ , It is characterized by the above-mentioned.
Further, in the developing device of the present invention, the toner layer regulating member is a metal flat plate and has a bent portion, the bent portion abuts on the developing roller, and the toner layer regulating member in the radial cross section of the developing roller. When the radius of curvature of the contact portion of the member with the developing roller is R, R ≧ 0.5.
The developing device of the present invention is further characterized in that the arithmetic average roughness Ra of the surface of the developing roller is 1.5 to 2.5.
Further, in the developing device of the present invention, the material of the foam is acrylic resin, polyethylene resin, polyester resin, polyurethane resin, polysulfonic acid resin, epoxy resin, phenol resin, styrene resin, nylon resin, polyvinyl chloride, Resins such as alkyd resin, silicone resin, urea resin, melamine resin, fluorine resin, polybutadiene, butadiene styrene rubber, butadiene acrylonitrile rubber, polychloroprene, polyisoprene, chlorosulfonated polyethylene, polyisobutylene, isobutylene isoprene rubber, acrylic rubber And at least one copolymer selected from synthetic rubbers such as urethane rubber, polysulfide-based synthetic rubber, fluorine rubber, and silicone rubber.
The developing device of the present invention is further characterized in that the foam contains a polarity control agent.
Further, in the developing device of the present invention, the polarity control agent is at least one selected from a coupling agent, a resin modified with a coupling agent, an ionic dye / pigment or an organometallic compound, a resin, and a modified silicone oil. It is a seed.
An image forming apparatus according to the present invention includes any one of the developing devices described above.

In the developing device and the image forming apparatus including the developing device as the means for solving the problem, when the individual particles of the one-component toner are projected onto a plane, they are defined by the circumference of an equivalent circle having the same projected area / the circumference of each particle. The average value of the circularity is in the range of 0.95 to 1.0, and the toner supply roller is made of a foam, and the density of the foam is 150 to 200 kg / m ³ , so a nearly spherical toner is used. Even in this case, the toner scraping property from the developing roller by the toner supply roller can be maintained over time. As a result, blade sticking and developing roller filming do not occur. Further, when the bending radius R of the doctor blade is 0.5 mm or more, sufficient toner transportability is ensured without increasing the roughness of the developing roller surface even for toner having an average circularity of 0.95 or more. It is possible.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 shows an image forming apparatus including an embodiment of the developing device of the present invention. In the image forming apparatus main body, yellow (Y), magenta (M), cyan (C), and black (K) image carriers (also referred to as photoconductors) 1Y, M, C, and K are arranged in parallel. It is arranged. That is, this image forming apparatus is a tandem type color laser copying machine. The image forming apparatus main body includes a printer unit 100 and a paper feeding device 200 on which the printer unit 100 is placed. The pressure plate open / close scanner includes a scanner unit main body 300 fixed on the printer unit 100 and an automatic document feeder 400 rotatably provided on the scanner unit main body 300.
The printer unit 100 forms an image including four process cartridges 18Y, 18M, 18C, and 18K for forming an image of each color of yellow (Y), magenta (M), cyan (C), and black (K). A unit 20 is provided. Y, M, C, and K added after the numbers of the respective symbols indicate members for yellow, magenta, cyan, and black. In addition to the process cartridges 18Y, 18M, 18C, and 18K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a belt fixing type fixing device 25, and the like are disposed.

  When copying a document, the user sets, for example, a bundle of sheet documents on the document table 30 of the automatic document feeder 400. Alternatively, one original is placed on the contact glass 32. When placing the sheets one by one on the contact glass 32, first, the automatic document feeder 400 is rotated upward with respect to the scanner unit main body 300 to expose the contact glass 32. Thereafter, the document is placed on the contact glass 32, and then the automatic document feeder 400 is rotated downward to sandwich the document with the contact glass 32.

When the copy start switch is pressed after the document is set in this way, the document reading operation by the scanner unit main body 300 starts. However, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 operates to move the sheet document to the contact glass 32 prior to this document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. The reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, then passes through the imaging lens 35, and finally enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light. When the sheet document is placed on the contact glass 32 by the automatic document feeder 400, the sheet document is discharged to the document discharge unit 31.
In parallel with such document reading operation, each device in each of the process cartridges 18Y, 18M, 18C, 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 start driving. Then, based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled so that Y, M, C, K toner images are formed on the image carriers 1Y, 1M, 1C, 1K. It is formed. These toner images are superimposed and transferred onto the intermediate transfer belt 110 to form a four-color toner image.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding device 200 starts the paper feeding operation. In this paper feeding operation, one of the plurality of paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of paper feeding cassettes 44 provided in multiple stages in the paper bank 43. . When the transfer paper is sent out, the transfer paper is separated one by one by the separation roller 45, and the transfer paper enters the paper feed path 46 one by one. Thereafter, the sheet is conveyed toward the secondary transfer nip by the conveying roller pair 47. On the other hand, paper feed from the manual feed tray 51 may be performed instead of paper feed from the paper feed cassette 44. In this case, the manual paper feed roller 50 is selectively rotated, and the transfer paper is fed into the image forming apparatus by the manual paper feed roller 50. At this time, a plurality of transfer papers are to be transported as a unit by mutual frictional force, but because of the separation roller 52, the transfer papers are transported one by one. In this way, the transfer sheets are fed one by one to the manual feed path 53 of the printer unit 100.

Hereinafter, components of the image forming apparatus (the optical writing unit 21, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25) will be described. The description will be made on the assumption that a full-color image is formed.
First, the optical writing unit 21 will be described. The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of the image carrier 1 with laser light based on image data. As a result, the surface potential of the image carrier 1 uniformly charged by the charging device is attenuated at the portion irradiated with the laser beam. By this attenuation, an electrostatic latent image is formed on the surface of the image carrier 1. The electrostatic latent image formed in this way is developed by the developing units 7Y, 7M, 7C, and 7K to become a toner image.
The toner image formed on the image carrier 1 is primarily transferred to the intermediate transfer belt 110. Since toner remains on the surface of the image carrier 1 after the primary transfer, the surface of the image carrier 1 is cleaned by the cleaning device. Then, after passing through the lubricant application device, the charge is removed by the static eliminator, uniformly charged by the charging device, and returned to the initial state.

  Next, the intermediate transfer unit 17 will be described. The intermediate transfer unit 17 includes an intermediate transfer belt 110 and a belt cleaning device 90. The intermediate transfer unit 17 includes a driven roller 14, a drive roller 15, a secondary transfer roller 16, and four primary transfer rollers 62Y, 62M, 62C, 62K. The intermediate transfer belt 110 is stretched by a plurality of rollers including the driven roller 14. The intermediate transfer belt 110 moves endlessly by the rotation of the driving roller 15 driven by a motor. The four primary transfer rollers 62Y, 62M, 62C, 62K are arranged so as to be in contact with the inner peripheral surface of the intermediate transfer belt 110, respectively, and a primary transfer bias voltage is applied from a power source (not shown). Further, the primary transfer rollers 62Y, 62M, 62C, 62K press the intermediate transfer belt 110 from the inner peripheral surface thereof toward the image carriers 1Y, 1M, 1C, and 1K to form a primary transfer nip. Due to the influence of the primary transfer bias voltage, a primary transfer electric field is formed between the image carrier 1Y, M, C, K and the primary transfer roller 62Y, M, C, K (primary transfer nip).

The Y toner image formed on the image carrier 1Y is primarily transferred to the intermediate transfer belt 110 due to the influence of the primary transfer electric field and nip pressure. M, C, and K toner images formed on the image carriers 1M, 1C, and 1K are sequentially superimposed on the Y toner image. By this superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image), which is a multiple toner image, is formed on the intermediate transfer belt 110.
The four-color toner image transferred to the intermediate transfer belt 110 is transferred to transfer paper at the secondary transfer nip. The intermediate transfer belt 110 in which the toner remains on the surface after passing through the secondary transfer nip is sandwiched between the driven roller 14 and the belt cleaning device 90, where it is cleaned by the belt cleaning device 90.

  Next, the secondary transfer device 22 will be described. The secondary transfer device 22 is provided below the intermediate transfer unit 17. Further, the secondary transfer device 22 includes a paper transport belt 24 stretched by two stretch rollers 23. The paper transport belt 24 moves endlessly as the at least one of the stretching rollers 23 rotates. Of the two stretching rollers 23, the stretching roller 23 disposed on the right side in the drawing is paired with the secondary transfer roller 16 and sandwiches the intermediate transfer belt 110 and the paper transport belt 24. By this sandwiching, the intermediate transfer belt 110 and the paper transport belt 24 come into contact with each other to form a secondary transfer nip. A secondary transfer bias voltage having a polarity opposite to that of the toner is applied to the right tension roller 23. By applying the secondary transfer bias voltage, a secondary transfer electric field in which the toner electrostatically moves from the intermediate transfer belt 110 toward the stretching roller 23 in the secondary transfer nip is formed. Then, the four-color toner image is transferred to the transfer sheet fed to the secondary transfer nip by the registration roller pair 49 so as to be synchronized with the four-color toner image transferred to the intermediate transfer belt 110 due to the influence of the secondary transfer electric field and the nip pressure. Is transcribed. Instead of applying the secondary transfer bias voltage to the stretching roller 23, a method of charging the transfer paper in a non-contact state with a charging charger may be employed.

  In the paper feeding device 200 provided at the lower part of the main body of the image forming apparatus, a plurality of paper feeding cassettes 44 capable of storing a plurality of transfer papers in a bundled state are arranged at intervals in the vertical direction. A paper feed roller 42 is pressed against the uppermost transfer paper of the paper feed cassette 44. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 46.

  A plurality of conveyance roller pairs 47 and a registration roller pair 49 provided near the end of the paper feed path 46 are provided in the paper feed path 46 that receives the transfer paper fed from the paper feed cassette 44. The transfer paper is conveyed toward the registration roller pair 49 via the conveyance roller pair 47. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip with the endless movement of the belt. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the four-color toner image can be transferred in the secondary transfer nip. As a result, the four-color toner image on the intermediate transfer belt 110 is transferred to the transfer paper at the secondary transfer nip. The transfer paper on which the full-color image is printed in this manner is moved along with the endless movement of the paper transport belt 24, and then sent from the paper transport belt 24 to the fixing device 25.

Finally, the fixing device 25 will be described. The fixing device 25 includes a belt unit which is a device that moves the fixing belt 26 endlessly while being stretched by two rollers, and a pressure roller 27 that presses the fixing belt 26. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed by the pressure roller 27 includes a heat source (not shown) inside, and heats the fixing belt 26 by the heat generated by the roller. The heated fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.
The transfer sheet on which the fixing process has been performed by the fixing device 25 is discharged to a stack portion 57 protruding from the left side plate in the figure of the printer housing, or is formed on the other side in order to form a toner image. Return to the next transfer nip.

  FIG. 2 shows details of the developing unit 7. A developing container 71 of the developing unit 7 shown in FIG. 2 contains a predetermined amount of non-magnetic one-component toner T, and supplies a sponge-like toner made of a foam disposed under the developing container 71. The toner T is supplied to the roller 72. The toner supply roller 72 and the development roller 73 rotate at a predetermined linear velocity ratio in the direction of the arrow in the drawing, and the toner is supplied from the toner supply roller 72 to the development roller 73. The surface layer of the developing roller 73 is made of an elastic member, and adhesion of toner is enhanced by attaching coarse particles to the elastic member or roughening the elastic member itself. The toner adhering to the developing roller 73 is frictionally charged at the nip portion between the doctor blade 74, which is a toner layer regulating member, and the developing roller 73, and becomes negative polarity. Then, a toner layer having a predetermined thickness is formed on the developing roller 73 by the toner that has passed through the blade nip portion. In front of the blade nip portion, more toner than necessary is attached to the developing roller 73, so that excess toner is blocked by the doctor blade 74 and returns to the toner supply roller 72 side. At this time, if the weight of the toner is applied to the developing roller 73 side, the circulation property of the toner in front of the doctor blade 74 is lowered. For this reason, in the developing unit 7 of the present embodiment, a pressure relief plate 75 is provided on the front portion of the doctor blade 74 so as to allow toner to escape from the surface of the developing roller so that the weight of the toner is not applied to the developing roller 73.

The doctor blade 74 is a metal flat plate and has a bent portion. The bent portion contacts the developing roller 73, and the curvature of the contact portion of the doctor blade 74 with the developing roller 73 in the radial cross section of the developing roller 73. When the radius is R, R ≧ 0.5.
When one-component toner particles are projected onto a plane,
The average value of the circularity defined by the circumference of the equivalent circle having the same projected area / the circumference of the toner particles is in the range of 0.95 to 1.0, and the toner supply roller 72 is made of a foam. The density is 150 to 200 kg / m ³ . The reason for setting it to 150 kg / m ³ or more is that the scraping performance of the toner is maintained over time. The reason why it is set to 200 kg / m ³ or less is that the cells are not easily filled with toner even over time, and the scraping performance is maintained.

  Examples of the sponge-like surface agent for the toner supply roller 72 include acrylic resin, polyethylene resin, polyester resin, polyurethane resin, polysulfonic acid resin, epoxy resin, phenol resin, styrene resin, nylon resin, polyvinyl chloride, alkyd resin, Resins such as silicone resin, urea resin, melamine resin, fluorine resin, polybutadiene, butadiene styrene rubber, butadiene acrylonitrile rubber, polychloroprene, polyisoprene, chlorosulfonated polyethylene, polyisobutylene, isobutylene isoprene rubber, acrylic rubber, urethane rubber Synthetic rubbers such as polysulfide-based synthetic rubber, fluorine rubber, and silicone rubber can be used. Of course, these resins can be used alone, as well as those obtained by copolymerizing the constituent components of these resins in monomer units, and moreover, two or more combinations such as a polymer material composed of a combination of urethane and acrylic. Can also be used. These surface layer resins may be coated or coated by using an extruder or the like in addition to a method of dissolving and dispersing in an appropriate solvent and coating as a paint.

Further, a polarity control agent for controlling the toner having a reverse polarity due to charge injection or discharge during transfer to a negative polarity may be applied to the surface layer of the toner supply roller 72. The polarity control agent can be applied by a method of dispersing and mixing the roller surface layer, a method of coating the roller surface layer by means such as dipping, and the like. Examples of such polarity control agents include coupling agents, resins modified with coupling agents, ionic dyes and pigments, organometallic compounds, resins, and modified silicone oils. A coupling agent having stable controllability is preferred.
Examples of the coupling agent include silane coupling agents, titanate coupling agents, and aluminum coupling agents. Specific examples are shown below.
Examples of the silane coupling agent include trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, and the like. It is done.

The following two types of toner are put in the developing unit 7 shown in FIG. 2 under certain conditions, and the amount of toner adhering per unit area on the developing roller 73 when the apparatus is driven for about 30 seconds. The measured values are shown in FIG.
One type of toner (referred to as toner A) is a toner with an average particle size of 5.8 μm produced by a pulverization method, and the other type (referred to as toner B) is a toner with an average particle size of 5.3 μm produced by a polymerization method. is there. The average circularity of each toner is toner A: 0.93 and toner B: 0.96. The average circularity of 1.0 is a perfect circular shape on the projection surface, and the smaller the circularity value, the more different from the spherical shape. The pulverized toner usually has a shape with an average circularity of 0.93 or less, but a polymer toner can produce a toner with an average circularity of 0.95 or more.

The parameter on the horizontal axis in FIG. 3 is the arithmetic average roughness Ra of the developing roller surface. As can be seen from the graph, when the toner A and the toner B are compared, in the case of the same Ra value, the toner B having a higher degree of circularity has a lower toner adhesion amount on the developing roller.
In general, in the case of a nearly spherical toner, it is necessary to increase the toner conveying force by roughening the surface of the developing roller in order to obtain a desired toner adhesion amount. However, when the surface roughness of the developing roller increases, the toner scraping performance on the developing roller by the toner supply roller decreases. That is, there is a trade-off relationship. In the present invention, as confirmed from the experimental results described later, the present inventors have found a condition that allows even a nearly spherical toner to adhere a sufficient amount of toner to the developing roller.
The polymerized toner (toner B) can be produced using a suspension polymerization method, an emulsion polymerization method, or the like. Hereinafter, these toner production methods and materials, additives, and the like used in the production methods will be described.

(Suspension polymerization method)
A colorant, a release agent and the like are dispersed in an oil-soluble polymerization initiator and a polymerizable monomer, and then emulsified and dispersed by an emulsification method described later in an aqueous medium containing a surfactant and other solid dispersants. Thereafter, a polymerization reaction is performed to form particles, and excess surfactant and the like are washed away to obtain toner particles.
Polymerizable monomers such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, acrylamide, methacrylamide, diacetone Functional groups can be introduced on the surface of toner particles by using a part of acrylate or methacrylate such as acrylamide or these methylol compounds, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine, dimethylaminoethyl methacrylate and other amino groups. .
Further, by selecting a dispersant having an acid group or a basic group as the dispersant to be used, the dispersant can be adsorbed and left on the particle surface to introduce a functional group.

(Emulsion polymerization aggregation method)
A water-soluble polymerization initiator and a polymerizable monomer are emulsified in water using a surfactant, and a latex is synthesized by an ordinary emulsion polymerization technique. Separately, a dispersion in which a colorant, a release agent and the like are dispersed in an aqueous medium is prepared, and after mixing, the toner is aggregated to a toner size and heat-fused to obtain a toner.
A functional group can be introduced onto the surface of the toner particles by using a latex similar to the monomer that can be used in the suspension polymerization method.

(Surfactant)
In common with any toner production method, a dispersion stabilizer such as a surfactant and resin fine particles is appropriately added when forming the particles. These are added for the purpose of controlling the toner particle size.
Among these, surfactants are examples of those that affect the chargeability of the toner after particle formation.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned. Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

Further, as the cationic surfactant, aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent F-300 (Neos), and the like.
In particular, by using the fluorine-containing quaternary ammonium salt compound represented by the general formula (1), it is possible to obtain a stable developer with little change in charge amount when the environment changes.

(In the formula, X, Y, R1 to R4, r and s each represent the following: X: —SO2— or —CO—, R1, R2, R3, R4: hydrogen atom, carbon number of 1 to 10; Lower alkyl group or aryl group, Y: I or Br, r, s: an integer of 1-20.)

In the present invention, the charging characteristics can be stabilized by defining the washing temperature so that the amount of the surfactant remaining in the toner particles is a certain value or less.
In the toner according to the present invention, the base particles are produced by the following raw materials and production methods, for example.

(Modified polyester)
The toner according to the present invention contains a modified polyester (i) as a binder resin. The modified polyester (i) refers to a state in which a bonding group other than an ester bond is present in the polyester resin, or resin components having different configurations are bonded to the polyester resin by a covalent bond, an ionic bond, or the like. Specifically, the polyester terminal is modified by introducing a functional group such as a carboxylic acid group or an isocyanate group that reacts with a hydroxyl group into the polyester terminal and further reacting with an active hydrogen-containing compound.

  Examples of the modified polyester (i) include urea-modified polyester obtained by a reaction between a polyester prepolymer (A) having an isocyanate group and amines (B). As the polyester prepolymer (A) having an isocyanate group, a polycondensate of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC) and a polyester having an active hydrogen group, and a polyvalent isocyanate compound (PIC) And those reacted with. Examples of the active hydrogen group possessed by the polyester include a hydroxyl group (alcoholic hydroxyl group and phenolic hydroxyl group), an amino group, a carboxyl group, a mercapto group, and the like. Among these, an alcoholic hydroxyl group is preferable.

The urea-modified polyester is produced as follows.
Examples of the polyhydric alcohol compound (PO) include a dihydric alcohol (DIO) and a trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) and a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acids B1 to B5 blocked (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.). Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated. The urea-modified polyester may contain a urethane bond as well as a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

The modified polyester (i) used in the present invention is produced by a one-shot method or a prepolymer method. The weight average molecular weight of the modified polyester (i) is usually 10,000 or more, preferably 20,000 to 10,000,000, more preferably 30,000 to 1,000,000. The peak molecular weight at this time is preferably 1000 to 10000, and if it is less than 1000, the elongation reaction hardly occurs and the elasticity of the toner is small, and as a result, the hot offset resistance deteriorates. On the other hand, when it exceeds 10,000, the problem in production becomes high in the deterioration of fixability, particle formation and pulverization. The number average molecular weight of the modified polyester (i) is not particularly limited when the unmodified polyester (ii) described later is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. (I) When used alone, the number average molecular weight is usually 20000 or less, preferably 1000 to 10000, and more preferably 2000 to 8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color device are deteriorated.
In the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B) to obtain the modified polyester (i), a reaction terminator is used as necessary to adjust the molecular weight of the resulting urea-modified polyester. be able to. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those blocked (ketimine compounds).

(Unmodified polyester)
In the present invention, not only the modified polyester (i) is used alone, but also the unmodified polyester (ii) can be contained as a binder resin component together with the (i). By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color device are improved, which is preferable to the single use. Examples of (ii) include polycondensates of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC), which are the same as the polyester component (i), and preferred ones are also the same as (i). . Further, (ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, for example, may be modified with a urethane bond. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, the polyester component (i) and (ii) preferably have similar compositions. In the case of containing (ii), the weight ratio of (i) to (ii) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75, Particularly preferred is 7/93 to 20/80. If the weight ratio of (i) is less than 5%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The peak molecular weight of (ii) is 1000-10000 normally, Preferably it is 2000-8000, More preferably, it is 2000-5000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. As for the acid value of (ii), 1-5 are preferable, More preferably, it is 2-4. Since a high acid value wax is used for the wax, a low acid value of the binder resin component leads to chargeability and high volume resistance, so it is easy to match a toner used for a two-component developer.

  The glass transition point (Tg) of the binder resin is usually 35 to 70 ° C., preferably 55 to 65 ° C. If the temperature is lower than 35 ° C., the heat-resistant storage stability of the toner deteriorates, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the toner of the present invention tends to have good heat storage stability even when the glass transition point is low, as compared with known polyester-based toners. Show.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salt or compound, tungsten simple substance or compound, fluorine activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenol-condensate E-89 (above, manufactured by Orient Chemical Co., Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, manufactured by Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY
VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (manufactured by Carlit Japan) , Copper phthalocyanine, perylene, quinacridone, azo pigments, and other high molecular compounds having a functional group such as a sulfonic acid group, a carboxyl group, and a quaternary ammonium salt. Of these, substances that control the negative polarity of the toner are particularly preferably used. The amount of the charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline and petrolatum. And petroleum wax. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melted and kneaded together with the master batch and the binder resin, and of course, may be added when dissolved and dispersed in the organic solvent.

(External additive)
As the external additive, inorganic fine particles such as a metal oxide, a metal carbide, a metal nitride, and a metal carbonate can be used. Specifically, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide Cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.
Furthermore, organic fine particles can be used as the external additive. Specifically, polymer-based fine particles, for example, polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, methacrylic acid ester, acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine, nylon, heat Polymer particles made of a curable resin may be used.

Further, the external additive used in the toner of the present invention can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents that may contain alkyl groups, fluorinated alkyl groups, titanate coupling agents, coupling agents such as aluminum coupling agents, silicone oils, higher fatty acids, fluorine compounds and the like are preferable surface treatment agents. Can be mentioned.
In particular, a silane coupling agent which is an example of a coupling agent is used for improving the degree of hydrophobicity and fluidity. Specifically, as the silane coupling agent, chlorosilane, alkoxysilane, silazane, special silylating agent and the like can be used, and alkoxysilane is more preferable. Examples of the alkoxysilane include vinyltrimethoxysilane, propyltrimethoxysilane, I-butyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, and n-dodecyltrimethoxy. A silane etc. can be mentioned.
As the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane or the like can be used, and fluorine-containing siloxane or the like may be used.
The fluorine compound is preferably an organosilicon compound having a fluorine atom, such as 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, 3,3,3-trifluoropropyl. Trimethoxysilane, methyl-3,3,3-trifluoropropyldichlorosilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3,3,4,4,5,5,6,6,6- Nonafluorohexylmethyldichlorosilane and the like can be mentioned.
Further, examples of higher fatty acids include stearic acid, oleic acid, palmitic acid, and linoleic acid, and metal salts of these higher fatty acids may be used. Specific examples include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate, zinc oleate, manganese oleate, zinc palmitate, zinc linoleate, and calcium linoleate.

In the toner of the present invention, the external additive is dry mixing in which inorganic / organic fine particles such as hydrophobic silica fine powder are externally added in a mixer together with a mixed medium such as glass beads. For mixing external additives, a general mixer is used, but it is preferable to equip a jacket or the like to adjust the internal temperature. The external additive is appropriately added at the beginning or in the middle. Examples of the mixer include a V-type mixer, a rocking mixer, a Roedige mixer, a Nauter mixer, and a Henschel mixer.
In addition, wet mixing is used in which the toner is externally added in an aqueous and / or alcohol solvent. In this wet mixing, an external additive is added to a toner dispersed in an aqueous solvent and adhered to the toner surface. Further, when the external additive has been subjected to a hydrophobic treatment, it may be dispersed after a small amount of alcohol or the like is used in combination to lower the interfacial tension to facilitate wetting. Thereafter, the solvent can be removed by heating and fixed to prevent desorption. As a result, the external additive can be uniformly dispersed on the toner surface. Further, when the toner and the external additive are dispersed in the aqueous solvent, the external additive can be uniformly dispersed on the toner surface by adding the surfactant. Further, it is preferable to use an external additive or a surfactant having a polarity opposite to that of the toner.

Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.
(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium used for dispersion emulsification may be water alone, alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may contain an organic solvent such as
The amount of the aqueous medium used for the dispersion emulsification with respect to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.

Further, in order to improve dispersion in the aqueous medium used for dispersion emulsification, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.
Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

Further, as the cationic surfactant, aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent F-300 (Neos), and the like.
In particular, by using the fluorine-containing quaternary ammonium salt compound represented by the general formula (1), it is possible to obtain a stable developer with little change in charge amount when the environment changes.

(In the formula, X, Y, R1 to R4, r and s each represent the following: X: —SO2— or —CO—, R1, R2, R3, R4: hydrogen atom, carbon number of 1 to 10; Lower alkyl group or aryl group, Y: I or Br, r, s: integer of 1-20)

As the resin fine particles, any resin can be used as long as it can form an aqueous dispersion, and it may be a thermoplastic resin or a thermosetting resin. Examples thereof include vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin, two or more of the above resins may be used in combination.
Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained. For example, vinyl resins are polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid-acrylic acid esters. Examples thereof include resins such as a polymer, a styrene-acrylonitrile copolymer, a styrene-maleic anhydride copolymer, and a styrene- (meth) acrylic acid copolymer. The average particle size of the resin fine particles is 5 to 200 nm, preferably 20 to 300 nm. In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after strong stirring in a certain temperature range, toner base particles can be produced by removing the solvent. When a dispersion stabilizer that is soluble in an acid or alkali such as calcium phosphate is used, the calcium phosphate is dissolved from the toner base particles by a method such as dissolving the calcium phosphate with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.
The end point of washing is to collect a small amount of filter cake before drying, add ion exchange water at 1 ° C. to 10 ° C., more preferably 1 ° C. to 5 ° C. of the toner Tg, (After 10 minutes at 12,000 rpm), the mixture is filtered under reduced pressure, washed with water and dried until the specific conductivity of the filtrate is 60 μS / cm or less, more preferably 35 μS / cm or less. .

5) Toner is obtained by externally adding inorganic fine particles such as silica fine particles and titanium oxide fine particles to the toner base particles obtained above.
The external addition of the inorganic fine particles is performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

(Average circularity)
Further, the toner B of the present embodiment has an average circularity of 0.95 or more. Toner having a high degree of circularity is easily affected by the developing electric field, and is developed faithfully along the electric field of the electrostatic latent image. When reproducing minute latent image dots, fine line reproducibility is enhanced by dense and uniform development. In addition, toner with a high degree of circularity has a smooth and moderate fluidity, so it is easily affected by the electric field, and easily transfers faithfully along the electric field, resulting in a high transfer rate and high-quality images. Can be obtained. However, if the average circularity of the toner is less than 0.95, faithful development and transfer with a high transfer rate cannot be performed, so the average circularity is preferably 0.95 or more.

Next, toner scraping performance by the toner supply roller will be described. During the output of all solid images, almost 100% of the toner layer on the developing roller moves onto the image bearing member 1 at the nip portion between the image bearing member 1 and the developing roller 73 as shown in FIG.
In the figure, the shaded portion is a toner layer, which is actually a very thin layer, but in FIG. 4 it is shown as a thick layer for easy understanding as a schematic diagram. Since almost no toner remains at the position B indicated by the arrow, the toner layer at the position A indicated by the arrow is supplied from the toner supply roller 72 and passes through the doctor blade 74 only once. On the other hand, when the developing roller 73 is rotating in the blank paper portion, as shown in FIG. 5, the toner remains at the position B and is scraped once by the toner supply roller 72, and another toner is supplied. The At this time, if almost 100% of the toner is scraped off by the toner supply roller 72, the toner at the position A is only the toner supplied from the toner supply roller 72 as in the case of outputting all the solids. When the toner adhesion amount on the developing roller 73 at the position A is measured, the amount of all solid output and the amount of blank paper are almost the same. On the other hand, if the scraping property of the toner supply roller 72 is low, the newly supplied toner is added to the toner that is not scraped off and remains on the developing roller 73, and therefore the toner adhesion amount at the position A Increases compared to the case of full solid output, and the difference increases as the scraping property decreases.

  FIG. 6 shows the toner adhesion amount on the developing roller when the white paper is driven for 1 hour under a certain developing unit condition using the toner produced by the polymerization method for one hour under the condition of the white paper and when the solid image is output. Indicates. As shown in the drawing, it can be seen that the difference in the toner adhesion amount between the blank paper after 1 hour driving and the full solid output becomes very large, and the scraping property by the toner supply roller is lowered with time. This is considered to be because the toner on the surface of the toner supply roller, which is a foam, is considerably clogged with time, making it difficult to scrape off the toner on the developing roller. For this reason, it is considered that the toner adhesion amount on the developing roller at the time of blank paper and the output of all solids coincides with the initial time and with time, and when the fluctuation is small, it is considered that the scraping property does not deteriorate even with time. Factors that may be effective for scraping properties were set as control factors at the time of all solid output and at the initial time and time, and orthogonal experiments were performed to evaluate the toner adhesion amount on the developing roller with the desired characteristics of quality engineering. When the result was analyzed, the cause-effect diagram of the SN ratio was the result of FIG.

In FIG. 7, the levels of the factors A, B, and C are indicated as the first, second, and third levels, respectively. The density level of the sponge portion of the toner supply roller is 100 kg / m ³ , 150 kg / m ³ , and 200 kg / m ³ . As can be seen from the figure, the effect of the density of the sponge portion of the toner supply roller is larger than that of other factors, and it can be seen that a large gain can be obtained by setting the density to 150 kg / m ³ . The high density of the foam means that the cell diameter is small and the number of cells per unit volume is large, and it is considered that the cells are not easily filled with toner even over time, and the scraping performance is maintained.

As can be seen from FIG. 3, even with toner B having a circularity of 0.95 or more, a desired toner adhesion amount can be obtained by roughening the surface of the developing roller. However, in the contact development, if the surface of the developing roller is large, the graininess of the halftone portion is lowered due to the influence. Therefore, the toner must be attached to the desired developing roller without increasing the roughness of the developing roller surface.
Therefore, as the characteristics of the initial toner adhesion amount after blank paper, the above-mentioned toner and development unit are used, and a factor that may affect the toner adhesion amount is set as a control factor. Asked. FIG. 8 shows the result.
The levels of factors D and E are described as the first, second and third levels. It can be seen that the developing roller surface roughness Ra has the most significant difference, but the blade bending R also has a significant difference. In the pulverized toner, other factors have a significant difference with respect to the toner adhesion amount, but the effect of the other factors is small for toner having a high degree of circularity. Therefore, a desired toner adhesion amount can be obtained without increasing the roughness of the developing roller by setting the blade bend R to 0.5 mm or more even for toner with high circularity.

That is, in the above-described embodiment, when each particle of the one-component toner is projected onto a plane, the average value of the circularity defined by the circumference of the equivalent circle having the same projected area / the circumference of each particle is 0. The toner supply roller is in the range of 95 to 1.0, and the toner supply roller is made of a foam. The density of the foam is 150 to 200 kg / m ³ , so even when a nearly spherical toner is used, The toner scraping property from the developing roller can be maintained. As a result, blade sticking and developing roller filming do not occur. Further, when the bending radius R of the doctor blade is 0.5 mm or more, sufficient toner transportability is ensured without increasing the roughness of the developing roller surface even for toner having an average circularity of 0.95 or more. It is possible.

FIG. 1 is an explanatory view showing a first embodiment of the image forming apparatus of the present invention. FIG. 2 is an explanatory diagram showing details of the developing unit of FIG. FIG. 3 is a graph showing the results of measuring the toner adhesion amount on the developing roller using two types of toner. FIG. 4 is an explanatory diagram showing the flow of toner conveyance when the toner moves from the developing roller to the image carrier. FIG. 5 is an explanatory diagram showing the flow of toner conveyance when the toner does not move from the developing roller to the image carrier. FIG. 6 is an explanatory diagram showing the amount of toner adhering to the developing roller at the initial time and time of blank paper and solid image. FIG. 7 is a graph showing the relationship between the toner adhesion amount desired characteristic SN ratio on the developing roller and each factor. FIG. 8 is a graph showing the relationship between the average toner adhesion amount process on the developing roller and each factor. FIG. 9 is an explanatory diagram showing a main part of a conventional image forming apparatus. FIG. 10 is an explanatory view showing a conventional developing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 7 Developing unit 71 Developing container 72 Toner supply roller 73 Developing roller 74 Doctor blade 75 Pressure relief plate 14 Drive roller 15 Drive roller 16 Secondary transfer roller 17 Intermediate transfer unit 18 Process cartridge 20 Image forming unit 21 Optical writing Unit 22 Secondary transfer device 23 Tension roller 24 Paper transport belt 25 Fixing device 26 Fixing belt 27 Pressure roller 30 Document table 31 Document delivery unit 32 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Reading sensor 42 Paper feed roller 43 Paper bank 44 Paper feed cassette 45 Separation roller 46 Paper feed path 47 Transport roller pair 49 Registration roller pair 50 Manual paper feed roller 51 Manual feed tray 52 Separation roller 53 Manual paper feed path 57 Stack section 62 Primary Transfer roller 90 Belt cleaning device 100 Printer unit 110 Intermediate transfer belt 200 Paper feed device 300 Scanner unit body 400 Automatic document feeder 500 Image carrier 501 Intermediate transfer belt 502 Secondary transfer unit 503 Development unit 504 Charging roller 505 Fixing unit 506 Development Container 507 Toner supply roller 508 Developing roller 509 Doctor blade 510 Pressure relief plate 511 Image carrier unit T Toner

Claims (7)

A developing roller made of an elastic body that supplies a one-component toner to an electrostatic latent image formed on the image bearing member so as to be visualized;
A toner supply roller for supplying toner to the developing roller;
A toner layer regulating member that contacts the developing roller and makes the toner layer on the developing roller a thin layer;
In a developing device having
When one-component toner particles are projected onto a flat surface,
The average value of the circularity defined by the circumference of the equivalent circle having the same projected area / the circumference of the toner particles is in the range of 0.95 to 1.0,
The toner supply roller is made of a foam, and the density of the foam is 150 to 200 kg / m ³ . The developing device according to claim 1,
The toner layer regulating member is a metal flat plate and has a bent portion,
The bent portion contacts the developing roller,
When the radius of curvature of the contact portion of the toner layer regulating member with the developing roller in the radial cross section of the developing roller is R,
A developing device, wherein R ≧ 0.5. The developing device according to claim 1,
The developing device characterized in that the arithmetic average roughness Ra of the surface of the developing roller is 1.5 to 2.5. The developing device according to claim 1,
The foam material is acrylic resin, polyethylene resin, polyester resin, polyurethane resin, polysulfonic acid resin, epoxy resin, phenol resin, styrene resin, nylon resin, polyvinyl chloride, alkyd resin, silicone resin, urea resin, melamine resin Resins such as fluororesin, polybutadiene, butadiene styrene rubber, butadiene acrylonitrile rubber, polychloroprene, polyisoprene, chlorosulfonated polyethylene, polyisobutylene, isobutylene isoprene rubber, acrylic rubber, urethane rubber, polysulfide-based synthetic rubber, fluorine A developing device comprising at least one or more copolymers selected from synthetic rubbers such as rubber and silicone rubber. The developing device according to claim 4,
A developing device, wherein the foam contains a polarity control agent. The developing device according to claim 5,
The developing device, wherein the polarity control agent is at least one selected from a coupling agent, a resin modified with the coupling agent, an ionic dye / pigment, an organometallic compound, a resin, and a modified silicone oil. An image forming apparatus comprising the developing device according to claim 1.

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