JP4007530B2 - Multicolor image forming method and multicolor image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multicolor image forming method and a multicolor image forming apparatus for recording an image on paper or a resin film by an electrophotographic method, such as a printer, a facsimile machine, and a copying machine. The present invention relates to a color image forming method and a multicolor image forming apparatus.
[0002]
[Prior art]
Image formation by electrophotography is generally performed by developing an electrostatic latent image with toner to make it visible, and transferring the toner image obtained by development onto a sheet. The toner used for such image formation is usually produced by pulverizing and classifying a composition containing a binder resin and a colorant.
[0003]
As the binder resin used for the toner, a polyester resin having excellent transparency is used particularly for forming a multicolor image. However, since the polyester resin has a hydrophilic group, the moisture resistance is low and the chargeability of the toner is lowered. I will let you. For this reason, when an image is formed using a toner containing a polyester resin as a binder resin, there is a problem in that fog occurs and a high-quality image cannot be obtained particularly under high temperature and high humidity.
[0004]
On the other hand, in order to impart fluidity and uniform chargeability to the toner, silica fine powder is added to the toner, but since the silica fine powder has hydrophilicity, it absorbs moisture in the air, As a result, the toner aggregates and the chargeability is lowered.
[0005]
In order to solve such problems, it has been proposed to add a silica fine powder hydrophobized to the toner. For example, Japanese Patent Publication No. 7-120068 discloses that as a toner external additive, silica treated with hexamethyldisilazane (HMDS) is further subjected to spray treatment with dimethyl silicone oil. Has been.
[0006]
Japanese Examined Patent Publication No. 7-113783 describes a method of using, as an external additive of toner, a silicate fine powder treated with a silane coupling agent and further treated with various silicone oils. .
[0007]
However, even if the silica fine powder hydrophobized in this way is used, its effect is insufficient, and it has not been possible to prevent a decrease in toner chargeability, particularly under high humidity conditions.
[0008]
In recent years, small and inexpensive copiers and printers have been sold and are also used in ordinary households. Under these circumstances, normal temperature and humidity, high temperature and high humidity, low temperature It is desired to obtain high-quality images even under various environments such as low humidity.
[0009]
[Problems of the prior art]
As described above, conventionally, toners externally added with silica hydrophobized by various processing methods using various processing agents have been proposed. However, even such toner is insufficient to solve the deterioration of image quality under high temperature and high humidity. That is, even when toner with externally added hydrophobized silica is used, such toner has poor transferability. For example, when 6000 sheets are printed, voids (white background due to non-transfer of toner) may occur in the solid portion, Fog is generated under humidity.
[0010]
In particular, in a tandem color image forming apparatus in which a plurality of developing devices are arranged side by side, toner images of respective colors are sequentially superimposed and transferred onto a sheet, but transfer efficiency of toner used in a downstream developing device is particularly low. There was a problem.
[0011]
The present invention has been made under such circumstances, and is a multicolor image forming method capable of forming a high-quality image with good transferability at the time of overlap transfer and preventing occurrence of fog and voids. Another object is to provide a multicolor image forming apparatus.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention sequentially supplies a predetermined color toner corresponding to each image carrier onto a plurality of image carriers on which electrostatic latent images are formed. A multicolor image forming method for developing the electrostatic latent image and forming a multicolor image by sequentially transferring the color toner image formed by the development onto a transfer material each time it is developed, Each color toner is toner particle Silicone oil of 0.02 to 0.5 parts by weight per 100 parts by weight Addition do it Completion Among the plurality of image carriers arranged side by side, a color toner for developing an electrostatic latent image on an image carrier disposed downstream is provided. Against toner particles Silicone oil Addition The amount of the color toner that develops the electrostatic latent image on the image carrier disposed on the upstream side. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image of the image carrier disposed on the most downstream side is more than the amount. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image of the image carrier having the largest amount disposed on the most upstream side. Against toner particles Silicone oil Addition Provided is a multicolor image forming method characterized by having the least amount.
[0013]
The present invention also provides a plurality of image carriers each having an electrostatic latent image formed on the surface thereof, and a plurality of developing units that respectively form predetermined color toner images on the plurality of image carriers. A transfer unit that circulates and transfers a transfer material to each of the plurality of image carriers, and a color toner image on the image carrier is sequentially transferred onto the transfer material that is transferred to the image carrier by the transfer unit. A tandem type multi-color image forming apparatus comprising a plurality of transfer means and a fixing means for thermally fixing a toner image transferred onto the transfer material, wherein each color toner used in the plurality of developing means includes: toner particle Silicone oil of 0.02 to 0.5 parts by weight per 100 parts by weight Addition do it Completion Among the plurality of image carriers arranged side by side, a color toner for developing an electrostatic latent image on an image carrier disposed downstream is provided. Against toner particles Silicone oil Addition The amount of the color toner that develops the electrostatic latent image on the image carrier disposed on the upstream side. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image of the image carrier disposed on the most downstream side is more than the amount. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image of the image carrier having the largest amount disposed on the most upstream side. Against toner particles Silicone oil Addition Provided is a multicolor image forming apparatus characterized by having the smallest amount.
[0014]
In the multicolor image forming method and multicolor image forming apparatus of the present invention configured as described above, each color toner Added to the toner particles The silicone oil is preferably selected from the group consisting of dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl-modified silicone oil, and fluorine-modified silicone oil.
[0015]
Preferably, the plurality of transfer units respectively corresponding to the plurality of image carriers arranged side by side are contact-type transfer units arranged so as to press the transfer material against the corresponding image carriers.
[0016]
In the toner used in the multicolor image forming method and the multicolor image forming apparatus of the present invention, it is preferable to use a polyester resin as the binder resin.
[0017]
In the present invention, the toner Added to the particles As the silicone oil, one selected from the group consisting of dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl-modified silicone oil, and fluorine-modified silicone oil can be used. Silicone oil is 1-30cm ² It is desirable to have a kinematic viscosity of / s.
[0018]
toner Against particles Silicone oil Addition The lowest amount of toner used for upstream development Addition Amount is toner particle 0.02 to 0.14 parts by weight per 100 parts by weight, the highest amount of toner used for downstream development Addition The amount is preferably 0.2 to 0.5 parts by weight. Toner Against particles Silicone oil Addition The amount should not always increase stepwise from the upstream side to the downstream side, and if it does not decrease, the silicone oil between the toners used for adjacent development and transfer Addition The amount may be the same.
[0019]
For example, in a configuration in which four image carriers are arranged side by side, the toner used in the most downstream development and transfer Against toner particles Silicone oil Addition The highest amount of toner used in the most upstream development and transfer Against toner particles Silicone oil Addition The amount of toner used in the middle two developments and transfers is the lowest. Against toner particles Silicone oil Addition The amount is a value between the two and may be the same.
[0020]
A known charge control agent may be added to the toner according to the present invention as necessary. Examples of the charge control agent include a quaternary ammonium salt and a salt-forming compound thereof for obtaining a positively chargeable toner, and a metal complex or a metal complex salt of salicylic acid or alkylsalicylic acid for obtaining a negatively charged toner, Boron-containing potassium salt compounds are preferred. The addition amount of these charge control agents is preferably in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the toner.
[0021]
Further, various waxes may be added to the toner according to the present invention as a release agent for improving thermal characteristics. Further, in the toner of the present invention, inorganic oxide fine particles such as silica, titania and alumina as a fluidity improver may be added in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the toner.
[0022]
The toner according to the present invention can be manufactured by various manufacturing methods. Generally, it can be manufactured by the following manufacturing method.
First, a resin, a colorant, and, if necessary, a charge control agent, wax, a fluidity improver and the like are uniformly mixed by a Henschel mixer or the like. Next, this mixture is melt-kneaded using a kneader, an extruder, a roll mill or the like.
[0023]
Next, the kneaded material is coarsely pulverized using a hammer mill, a cutter mill, or the like, and then finely pulverized using a jet mill, a type 1 mill, or the like. Thereafter, the finely pulverized product is classified by a DS (dispersion classifier), a zigzag classifier or the like. The average particle size of the toner obtained by classification is preferably 3 to 18 μm.
[0024]
Thereafter, a silicone oil is added to the classified toner particles to produce a toner. In some cases, silica may be added to the toner using a Henschel Kimiser. Silica may have a surface hydrophobized using silicone oil or the like.
[0025]
As described above, according to the present invention, among the plurality of image carriers arranged side by side, the color toner for developing the electrostatic latent image of the image carrier disposed on the downstream side is developed. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image on the image carrier disposed upstream. Against toner particles Silicone oil Addition Since the amount is larger than the amount, the transferability when transferring a plurality of color toners is improved, the generation of voids is reduced, and a multicolor image that is faithful to the original and is clear and has good color reproducibility can be obtained. Is possible.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be shown to describe the present invention more specifically.
FIG. 1 schematically shows an internal configuration of a color image forming apparatus according to an embodiment of the present invention. First, the overall configuration of the color image forming apparatus will be described with reference to FIG.
[0027]
As shown in FIG. 1, the color image forming apparatus (main body apparatus) 30 is provided with an open / close tray 31 on the rear surface (left side in the figure), and is detachable from the front of the main body apparatus (right side in the figure) at the lower part. A paper cassette 32 is provided. A large number of sheets are placed and stored in the sheet cassette 32.
[0028]
The main body device 30 includes an upper lid 33 on its upper surface. Although not shown in the drawing, a power switch, a liquid crystal display device, a plurality of input keys and the like are disposed on the side of the front portion of the upper lid 33. The upper lid 33 forms a paper discharge tray 34 together with the rear upper surface of the main body device 30 at the rear part.
[0029]
Inside the main unit 30, a flat loop-shaped paper transport belt (hereinafter simply referred to as a belt) 35 is disposed at substantially the center so as to extend in the front-rear direction. And the driven roller 37. The belt 35 is driven by a driving roller 36 and circulates in a counterclockwise direction indicated by an arrow R in the figure. Four photosensitive drums 38 (38a, 38b, 38c, 38d) are arranged side by side in a multistage manner in the paper transport direction (from the right to the left in the figure) along the upper circulation portion of the belt 35.
[0030]
These photosensitive drums 38 (38a, 38b, 38c, 38d) are respectively surrounded (hereinafter, only the peripheral devices around the photosensitive drum 38d are typically shown with reference numerals), cleaner 41, initialization charging A roller 42, a writing head 43, and a developing device 44 (44d) are arranged. A contact-type sheet transfer device 39 presses against the photosensitive drum 38 via the belt 35 to form a transfer portion. Note that developing units 44a, 44b, and 44c are arranged for the photosensitive drums 38a, 38b, and 38c, respectively.
[0031]
The developing device (developing hopper) 44 (44d) includes a developing roller 45 rotatably supported at a lower opening portion thereof. The developing roller 45 is in contact with the peripheral surface of the photosensitive drum 38 to form a developing portion. The writing head 43 is disposed on the back surface of the upper lid 33 via a support member 46, and ascends and descends in an arc as the upper lid 33 is opened and closed, and descends when the upper lid 33 is closed to initialize charging. It is positioned between the roller 42 and the developing roller 45 to form a recording portion.
[0032]
A suction roller 47 is pressed against the driven roller 37 via the belt 35 at the upstream end portion of the upper circulation portion of the belt 35, thereby forming a paper carry-in portion. The suction roller 47 presses the belt 35 while applying a suction bias to the paper carried into the paper carry-in section, and electrostatically sucks the paper onto the belt 35.
[0033]
Each of the developing devices from the developing device 44a to the developing device 44d corresponding to the photosensitive drum 38d with respect to the photosensitive drum 38a at the most upstream side in the sheet conveying direction has three subtractive colors M (magenta), C (cyan), Each color toner of Y (yellow) and Bk (black) is accommodated. Each of these color toners contains silicone oil, and the silicone oil content of the toner contained in the downstream developer unit is higher than the silicone oil content of the toner contained in the upstream developer unit. Is adjusted to be higher.
[0034]
A standby roll pair 48 is disposed further upstream of the belt 35 in the conveying direction (right side in the figure), and a paper feed guide path 49 is disposed below the standby roll pair 48. A feed roll pair 51 is disposed at the lower end of the paper feed guide path 49. Is arranged. The aforementioned paper feed end of the paper cassette 32 is located upstream (downward) of the pair of feed rolls 51. A paper feed roller 52 is disposed above the paper feed end of the paper cassette 32. The paper feeding roller 52 takes out one sheet of the uppermost sheet stored in the paper cassette 32 every rotation and feeds it to the feeding roll pair 51.
[0035]
On the other hand, a fixing device 53, a paper discharge roll pair 54, and a switching lever 55 are provided downstream of the belt 35 in the paper conveyance direction (left side in the figure). The fixing device 53 includes a pressure roller, a fixing roller, a heat generating roller, a paper separation claw, a peripheral surface cleaning device, an oil application member, a thermistor, and the like assembled in a heat insulating casing, and a toner image transferred onto the paper. Is fixed on the paper.
[0036]
When the switching lever 55 is in the lower position as shown in the figure, the sheet is guided to the paper discharge tray 34 via the upper discharge path 56 and the paper discharge roll pair 57. On the other hand, when rotating upward, the sheet is guided to the open / close tray 31 formed on the rear surface of the main body apparatus.
[0037]
Between the belt 35 and the paper cassette 32, an electrical component 58 on which a circuit board can be mounted is disposed, and a control device composed of a plurality of electronic components is mounted on the circuit board.
[0038]
The control unit is composed of a controller unit and an engine unit. The controller unit includes a CPU (Central Processing Unit), ROM (Read Only Memory), EEPROM (Rewritable Read Memory), Frame Memory, Image Data Transfer Circuit, etc. It prepares, analyzes print data inputted from a host computer or the like, creates print data, and transfers it to the engine unit.
[0039]
The engine unit is equipped with a CPU, ROM, etc., and data and command signals from the controller unit, temperature sensor output, paper detection sensor output, etc. are input to its input side, and a motor (not shown) is driven on the output side. A motor driver for driving, a clutch driver for switching a drive system for transmitting the drive of the motor to each part, a print driver for driving the write head 43 based on the print data, an initialization charging roller 42, a developing roller 45, a transfer device, A bias power supply driver for supplying a predetermined bias voltage to the suction roller 47, a toner supply roller, a doctor blade, a developing unit scooping sheet, and the like, which will be described later, are connected. The engine unit drives and controls each unit based on data and command signals from the controller unit, the output of the temperature sensor, the output of the paper detection sensor, and the like.
[0040]
Next, the basic operation of the color image forming apparatus 30 described above will be described. First, when the power is turned on and the paper quality, number of sheets, print mode, and other specifications of the paper to be used are input as a key input or a signal from the connected host device, the paper supply roller 52 is rotated once by a drive mechanism (not shown). Then, the paper placed in the paper cassette 32 is fed to the standby roll pair 48 via the feed roll pair 51. The standby roll pair 48 temporarily stops its rotation, and waits for the conveyance timing in a state where the leading end of the sheet is brought into contact with the holding portion formed by the pair of rollers.
[0041]
Subsequently, the drive roller 36 rotates counterclockwise, and the driven roller 37 is driven to rotate in the same counterclockwise direction. As a result, the upper circulation portion of the belt 35 comes into contact with the four photosensitive drums 38a, 38b, 38c, and 38d, and the entire belt 35 circulates in the counterclockwise direction.
[0042]
At the same time, the developing devices 44a, 44b, 44c, 44d and the photosensitive drums 38a, 38b, 38c, 38d are sequentially driven in accordance with the printing timing. The photosensitive drum 38 rotates in the clockwise direction, the initialization charging roller 42 applies a uniform high negative charge to the circumferential surface of the photosensitive drum 38, and the writing head 42 is applied to the circumferential surface of the photosensitive drum 38. Exposure is performed in accordance with the image signal to form a low potential portion. As a result, an electrostatic latent image composed of the high negative potential portion by the initialization and the low negative potential portion by the exposure is formed. The developing roller 45 of the developing unit 44 transfers the toner to the low potential portion of the electrostatic latent image to form a toner image on the circumferential surface of the photosensitive drum 38 (reverse development).
[0043]
A standby roll so that the leading edge of the toner image on the peripheral surface of the most upstream photosensitive drum 38a is rotated and conveyed to a point facing the belt 35 so that the printing start position of the sheet coincides with that point. The pair 48 starts rotating and feeds the paper to the paper carry-in section.
[0044]
The driven roller 37 and the suction roller 47 sandwich and feed the fed paper together with the belt 35. The sheet is attracted to the belt 35 and conveyed to the first transfer unit formed by the photosensitive drum 38a and the transfer unit.
[0045]
The transfer device applies a transfer current output from the transfer bias power source to the sheet via the belt 35. Due to the transfer current applied from the transfer unit, an M (magenta) toner image on the photosensitive drum 38a is transferred to the sheet. Subsequently, a C (cyan) toner image is transferred at the second transfer portion from the upstream formed by the photosensitive drum 38b and the transfer device, and further, 3 from the upstream formed by the photosensitive drum 38c and the transfer device. The toner image of the second transfer portion Y (yellow) is transferred. Then, Bk (black) toner images are sequentially transferred at the most downstream transfer portion formed by the photosensitive drum 38d and the transfer device.
[0046]
In this case, the toner contained in the upstream developing device Against toner particles Silicone oil Addition The amount of toner stored in the developing device downstream of the amount Against toner particles Silicone oil Addition Since the amount is adjusted so as to be high, transferability at the time of overlap transfer is improved.
[0047]
In this way, the sheet on which the four color toner images have been transferred is separated from the belt 35 and carried into the fixing device 53. The fixing device 53 heat-fixes the toner image on the paper. After this image fixing, the paper is discharged by the paper discharge roll pair 54 with the toner image on the rear opening / closing tray 31 or on the upper paper discharge tray 34 with the toner image facing down.
[0048]
FIG. 2 is a side sectional view schematically showing the main part of the developing device 44. The developing device 44 shown in the figure is detachable from the color image forming apparatus 30 and is a developing unit that constitutes one image forming unit together with the drum unit. The developing device 44 includes a housing 61 that also serves as a toner hopper. A developing roller 45 made of a conductive rubber roller is rotatably held in a lower opening of the housing 61, and the toner 62 is accommodated in the housing 61. In addition, a toner stirring member 63 disposed so as to be buried in the toner 62 is provided.
[0049]
Further, a supply roller 64 made of a sponge body is disposed in pressure contact with the developing roller 45 at the lowermost portion of the developing device 44. The developing roller 45 is provided with a metal leaf spring doctor blade 65 in pressure contact with the oblique upper right circumferential surface thereof, and a developing unit scooping sheet (conductive regulation sheet) 66 disposed in contact with the lower circumferential surface. It is installed. The developing unit scooping sheet 66 is provided with a conductive regulation sheet biasing means described later including a bias power supply 71. On both sides of the doctor blade 65, sealing members 67 are provided to isolate the inside and outside of the opening of the housing 61 and prevent the toner 62 from leaking out.
[0050]
By the way, the toner 62 in the non-development portion remaining on the peripheral surface of the developing roller 45 after the development on the photosensitive drum 38 is scraped off in the housing 61 to eliminate the development memory. The sliding force of the supply roller 64 varies depending on the adhesion force of the toner 62 to the developing roller 45. That is, a strong rubbing force is required for a toner having a strong adhesive force, but a low rubbing force is sufficient for a toner having a weak adhesive force. It can be said that the adhesion force of the toner 62 to the developing roller 45 is substantially determined by the charging ability of the toner 62. That is, the smaller the triboelectric charge amount, the weaker the adhesive force, and therefore it is easier to scrape off from the developing roller 45.
[0051]
However, the triboelectric charge amount of the toner 62 is closely related to adhesion development (hereinafter referred to as “photosensitive member fogging”) that occurs at the time of development and becomes a problem. It is easy to generate fog. Therefore, in order not to cause such photoconductor fogging, it is necessary to increase the triboelectric charge amount of the toner 62. When the triboelectric charge amount of the toner 62 is increased, the adhesion force to the developing roller 45 is increased, so that it is necessary to apply a strong rubbing force to the supply roller 64.
[0052]
Repeating the rotation for a long time with such a strong rubbing force is not preferable because it causes deterioration of toner characteristics such as a decrease in charging ability and fluidity of the toner. For example, when the charge amount is reduced, the above-described photoreceptor fogging is generated, and when the fluidity is reduced, development loss of halftone printing is generated.
[0053]
In the developing device 44 having such a problem, in one embodiment of the present invention, first, the developing roller 45 is composed of a core metal and a cylindrical semiconductive (10) surrounding the core metal. ⁶ The developing bias of “−250 V” is applied from the bias power source 68 to the core metal. A predetermined amount of silicone oil is applied to the surface of the developing roller 45 as described above.
[0054]
Further, the supply roller 64 is made of a core metal and a cylindrical semiconductive material (10 ⁶ A supply bias of “−500 V” is applied from the bias power source 69 to the core metal.
[0055]
Further, the doctor blade 65 is formed of an elastic metal plate, and a doctor bias of “−500 V” is applied to the doctor blade 65 from the bias power source 69. Then, the developing unit scooping sheet 66 positioned on the upstream side of the supply roller 64 is electrically connected to the conductive member (10 ³ The sheet bias voltage in the range from 0 V (0 volt) to the developing bias voltage of the developing roller 45 is applied by the bias power supply 71 to the Ωcm.
[0056]
As described above, the developing unit scooping sheet 66 is made of a conductive member, and the sheet bias voltage in the range from 0 V to the developing bias voltage of the developing roller 45 is applied to the toner adhering to the developing roller 45. This is because the charge of 62 is reduced. Thereby, even with a weak rubbing force by the supply roller 64, the toner of the non-development portion that has adhered and returned on the developing roller 45 can be easily scraped off.
[0057]
2, for the sake of convenience, the developing bias voltage is applied to the developing roller 45 by a bias power source 68, and the sheet bias voltage is applied to the developing unit scooping sheet 66 by the bias power source 71. Although an example of performing individually is described, it is not necessary to separately provide power supplies in this way. That is, in the actual developing unit configuration in the present invention, for example, a voltage dividing circuit including a resistance element is provided in the unit, and the bias divided into each of the developing roller 45 and the developing unit scooping sheet 66 by the common bias power source of the apparatus main body. A voltage is applied.
[0058]
By using the color image forming apparatus and the image forming process having the above-described apparatus configuration, it is possible to obtain a multi-color image that is improved in transferability at the time of superimposing transfer, is less likely to generate voids, is faithful to a document, and is clear with good color reproducibility. Is possible.
[0059]
【Example】
Hereinafter, examples of the present invention will be shown, and the present invention will be described more specifically.
First, an example of producing a binder resin for toner used in each example will be described.
[0060]
Production Example 1 (Resin A)
Polyoxypropoxypropylene (2,2) -2.2-bis
1050 g of (4-hydroxyphenyl) propane
Polyoxypropoxyethylene (2,2) -2.2-bis
325 g of (4-hydroxyphenyl) propane
330 g of terephthalic acid
240g fumaric acid
Hydroquinone 0.5g
Each of the above compounds was housed in a 4-liter glass flask having a capacity of 2 liters, and a thermometer, a stainless steel stirring rod, a flow-down condenser, and a nitrogen inlet tube were attached to the flask. Next, while flowing nitrogen in an electric heating mantle heater, the reaction was carried out while tracking the acid value while stirring under reduced pressure at the first half of 180 ° C. and the second half of 200 ° C. to produce a polyester. The acid value of the obtained polyester was 27.0 (mgKOH / g).
[0061]
Production Example 2 (Resin B)
Polyoxypropoxypropylene (2,2) -2.2-bis
840 g of (4-hydroxyphenyl) propane
Polyoxypropoxyethylene (2,2) -2.2-bis
195 g of (4-hydroxyphenyl) propane
Terephthalic acid 249g
132 g of fumaric acid
1,2,5-Pensenetricarboxylic acid 29g
Dibutyltin oxide 2g
Hydroquinone 0.5g
Each of the above compounds was reacted using the same apparatus as in Production Example 1 with the same formulation and following the acid value. The acid value of the obtained polyester was 19.0 (mgKOH / g).
[0062]
Production Example 3 (Resin C)
Polyoxypropoxypropylene (2,2) -2.2-bis
578 g of (4-hydroxyphenyl) propane
Polyoxypropoxyethylene (2,2) -2.2-bis
176 g of (4-hydroxyphenyl) propane
72g of trimethylolpropane
472 g of isophthalic acid
Each of the above compounds was reacted using the same apparatus as in Production Example 1 with the same formulation and following the acid value. The acid value of the obtained polyester was 16.0 (mgKOH / g).
[0063]
Production Example 4 (Resin D)
Polyoxypropoxypropylene (2,2) -2.2-bis
770 g of (4-hydroxyphenyl) propane
Polyoxypropoxyethylene (2,2) -2.2-bis
720 g of (4-hydroxyphenyl) propane
690 g of terephthalic acid
120 g of tri-n-ethylhexyl 1,2,4benzenetricarboxylate
The above compound was subjected to the reaction using the same apparatus as in Production Example 1 with the same formulation and following the acid value. The acid value of the obtained polyester was 2.1 (mgKOH / g).
[0064]
Example 1
In the color image forming apparatus shown in FIG. 1, the silicone oil content of each color toner used in the developing unit on the downstream side in the transfer material conveyance direction, corresponding to each of the four image carriers, is supplied to the developing unit disposed upstream. Each color toner prepared as in Example 1-A, Example 1-B, Example 1-C, and Example 1-D so as to be larger than the silicone oil content of the toner to be used is treated as follows. Created by.
[0065]
Example 1-A
100 parts by weight of a polyester resin (resin A: acid value 27.0 mgKOH / g), 1.5 parts by weight of a charge control agent (LR-147 manufactured by Nippon Carlit Co., Ltd.), 2.0 parts by weight of a polypropylene resin, and a color pigment (red pigment) : Pig.Red 57: 1) 3.0 parts by weight are mixed with a Henschel mixer, melt-kneaded with a hot roll mill, cooled, coarsely pulverized with a hammer mill, and then finely pulverized with an air jet method. Dispersion was performed using a dispersion classifier to obtain a classified product having a particle size of 5 to 20 μm.
[0066]
100 parts by weight of this classified product, and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF96-500cs) (kinematic viscosity 5 cm ² / S) 0.14 part by weight was mixed with a Henschel mixer to obtain a toner powder treated with silicone oil.
[0067]
To 100 parts by weight of this toner powder, 1.5 parts by weight of silicon oxide fine powder (manufactured by Nippon Aerosil Co., Ltd .: RX-50) was further mixed with a Henschel mixer to obtain a red toner.
[0068]
Example 1-B
100 parts by weight of a polyester resin (resin A: acid value 27.0 mgKOH / g), 1.5 parts by weight of a charge control agent (LR-147 manufactured by Nippon Carlit), 2.0 parts by weight of a polypropylene resin, and a color pigment (copper b) Phthalocyanine: Pig.Blue 15: 3) 3.0 parts by weight are mixed with a Henschel mixer, melt-kneaded with a hot roll mill, cooled, coarsely ground with a hammer mill, and then finely ground with an air jet system. Then, the mixture was dispersed with a dispersion classifier to obtain a classified product having a particle size of 5 to 20 μm.
[0069]
100 parts by weight of this classified product, and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF96-500cs) (kinematic viscosity 5 cm ² / S) 0.16 part by weight was mixed with a Henschel mixer to obtain a toner powder treated with silicone oil.
[0070]
To 100 parts by weight of this toner powder, 1.5 parts by weight of silicon oxide fine powder (manufactured by Nippon Aerosil Co., Ltd .: RX-50) was further mixed with a Henschel mixer to obtain a blue toner.
[0071]
Example 1-C
100 parts by weight of a polyester resin (resin A: acid value 27.0 mgKOH / g), 1.5 parts by weight of a charge control agent (LR-147 manufactured by Nippon Carlit Co., Ltd.), 2.0 parts by weight of a polypropylene resin, and a color pigment (yellow pigment) , Disazo Yellow: Pig. Y-17) 3.0 parts by weight are mixed with a Henschel mixer, melt-kneaded with a hot roll mill, cooled, coarsely pulverized with a hammer mill, and then finely divided with an air jet method. The mixture was pulverized and dispersed with a dispersion classifier to obtain a classified product having a particle size of 5 to 20 μm.
[0072]
100 parts by weight of this classified product, and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF96-500cs) (kinematic viscosity 5 cm ² / S) 0.18 part by weight was mixed with a Henschel mixer to obtain a toner powder treated with silicone oil.
[0073]
To 100 parts by weight of this toner powder, 1.5 parts by weight of silicon oxide fine powder (manufactured by Nippon Aerosil Co., Ltd .: RX-50) was further mixed with a Henschel mixer to obtain a yellow toner.
[0074]
Example 1-D
100 parts by weight of a polyester resin (resin A: acid value 27.0 mgKOH / g), 1.5 parts by weight of a charge control agent (T-77 manufactured by Hodogaya Chemical Co., Ltd.), 2.0 parts by weight of a polypropylene resin, and a black pigment (carbon black) : Monarch 880) 4.0 parts by weight are mixed with a Henschel mixer, melt-kneaded with a continuous extruder, cooled, coarsely pulverized with a hammer mill, then finely pulverized with an air jet method and dispersed. Dispersion was carried out with a formula classifier to obtain a classified product having a particle size of 5 to 20 μm.
[0075]
100 parts by weight of this classified product, and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF96-500cs) (kinematic viscosity 5 cm ² / S) 0.2 part by weight was mixed with a Henschel mixer to obtain a toner powder treated with silicone oil.
[0076]
To 100 parts by weight of this toner powder, 1.5 parts by weight of silicon oxide fine powder (manufactured by Nippon Aerosil Co., Ltd .: RX-50) was further mixed with a Henschel mixer to obtain a black toner.
[0077]
Using the above red toner, blue toner, yellow toner, and black toner, when 6,000 sheets were printed with a color printer (Color Page Presto N4-612: Casio Co., Ltd.), the transferability in overlap transfer was good and voids were generated. There was no image output, and an image output faithful to the original and clear and having good color reproducibility was obtained.
[0078]
Further, when printing was performed in an environment of high temperature and high humidity of 32.5 ° C. and 80 RH%, a good image was obtained. Furthermore, when printing was performed in an environment of 10.5 ° C. and 20 RH%, a good image was obtained.
[0079]
Example 2
A red toner, a blue toner, a yellow toner, and a black toner were produced in the same manner as in Example 1 except that the resin B was replaced by resin B (acid value: 19.0 mgKOH / g) instead of resin A. .
[0080]
When 6,000 sheets of these toners are printed with a color printer (Color Page Presto N4-612: Casio Co., Ltd.), the transferability in the overlay transfer is good, there are no voids, and the color reproduction is faithful to the original and clear. Image output with good characteristics was obtained.
[0081]
Further, when printing was performed in an environment of high temperature and high humidity of 32.5 ° C. and 80 RH%, a good image was obtained. Furthermore, when printing was performed in an environment of 10.5 ° C. and 20 RH%, a good image was obtained.
[0082]
Example 3
A red toner, a blue toner, a yellow toner, and a black toner were produced in the same manner as in Example 1 except that the resin C was replaced with resin C (acid value: 16.0 mgKOH / g) instead of resin A. .
[0083]
When 6,000 sheets of these toners are printed with a color printer (Color Page Presto N4-612: Casio Co., Ltd.), the transferability in the overlay transfer is good, there are no voids, and the color reproduction is faithful to the original and clear. Image output with good characteristics was obtained.
[0084]
Further, when printing was performed in an environment of high temperature and high humidity of 32.5 ° C. and 80 RH%, a good image was obtained. Furthermore, when printing was performed in an environment of 10.5 ° C. and 20 RH%, a good image was obtained.
[0085]
Example 4
A red toner, a blue toner, a yellow toner, and a black toner were produced in the same manner as in Example 1 except that the resin D was replaced with a resin D (acid value: 2.1 mgKOH / g) instead of the resin A. .
[0086]
When 6,000 sheets of these toners are printed with a color printer (Color Page Presto N4-612: Casio Co., Ltd.), the transferability in the overlay transfer is good, there are no voids, and the color reproduction is faithful to the original and clear. Image output with good characteristics was obtained.
[0087]
Further, when printing was performed in an environment of high temperature and high humidity of 32.5 ° C. and 80 RH%, a good image was obtained. Furthermore, when printing was performed in an environment of 10.5 ° C. and 20 RH%, a good image was obtained.
[0088]
Example 5
The addition amount of silicone oil was adjusted to 0.12 parts by weight for red toner, 0.14 parts by weight for blue toner, 0.14 parts by weight for yellow toner, and 0.16 parts by weight for black toner, In the same manner as in Example 1, red toner, blue toner, yellow toner, and black toner were produced.
[0089]
When 6,000 sheets of these toners are printed with a color printer (Color Page Presto N4-612: Casio Co., Ltd.), the transferability in the overlay transfer is good, there are no voids, and the color reproduction is faithful to the original and clear. Image output with good characteristics was obtained.
[0090]
Further, when printing was performed in an environment of high temperature and high humidity of 32.5 ° C. and 80 RH%, a good image was obtained. Furthermore, when printing was performed in an environment of 10.5 ° C. and 20 RH%, a good image was obtained.
[0091]
Comparative Example 1
The addition amount of silicone oil was adjusted to 0.16 parts by weight for red toner, 0.14 parts by weight for blue toner, 0.12 parts by weight for yellow toner, and 0.12 parts by weight for black toner, respectively. In the same manner as in Example 1, red toner, blue toner, yellow toner, and black toner were produced.
[0092]
When 6,000 sheets of these toners were printed by a color printer (Color Page Presto N4-612: Casio Co., Ltd.), voids occurred and an image output with poor color reproducibility was produced. In particular, the transferability of black toner was poor, and the image was low in image density of black toner.
[0093]
Further, when printing was performed in a high temperature and high humidity environment of 32.5 ° C. and 80 RH%, the number of voids increased and an image output with extremely poor color reproducibility was obtained.
[0094]
【The invention's effect】
As described above in detail, according to the present invention, among the plurality of image carriers arranged side by side, the color toner for developing the electrostatic latent image of the image carrier disposed on the downstream side is developed. Against toner particles Silicone oil Addition The amount of color toner that develops the electrostatic latent image on the image carrier disposed upstream. Against toner particles Silicone oil Addition Since the amount is larger than the amount, the transferability when transferring a plurality of color toners is improved, the generation of voids is reduced, and a multicolor image that is faithful to the original and is clear and has good color reproducibility can be obtained. Is possible.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an internal configuration of a color image forming apparatus according to an embodiment of the present invention.
2 is a side sectional view schematically showing a main part of a developing device of the color image forming apparatus of FIG. 1;
[Explanation of symbols]
30. Color image forming apparatus
31 ... Opening and closing tray
32. Paper cassette
33 ... Upper lid
34 ... Output tray
35. Paper transport belt
36 ... Driving roller
37. Followed roller
38, 38a, 38b, 38c, 38d ... photosensitive drum
39. Sheet transfer device
41 ... cleaner
42. Initializing charging roller
43 ... Writing head
44a, 44b, 44c, 44d ... developing devices.

Claims (4)

An electrostatic latent image is formed on each surface, a predetermined color toner corresponding to each image carrier is sequentially supplied onto a plurality of image carriers arranged side by side, the electrostatic latent image is developed, and A multi-color image forming method for forming a multi-color image by sequentially transferring a color toner image formed by development onto a transfer material each time it is developed,
The respective color toners, Ri formed by adding 0.02 part by weight or more 0.5 parts by weight of silicone oil relative to 100 parts by weight of the toner particles, among the plurality of image bearing members which are the parallel, downstream The amount of silicone oil added to the toner particles of the color toner that develops the electrostatic latent image of the image carrier disposed on the image carrier is relative to the toner particles of the color toner that develops the electrostatic latent image of the image carrier disposed on the upstream side . silicone oil added amount or more, and static on the most downstream side is disposed most upstream end silicone oil amount to the toner particles of the color toner for developing an electrostatic latent image arranged image carrier the image bearing member A multicolor image forming method characterized in that the amount of silicone oil added to the toner particles of color toner for developing an electrostatic latent image is the smallest. The silicone oil that will be added to the toner particles of each color toner is dimethyl silicone oil, alkyl-modified silicone oil, alpha-methylstyrene-modified silicone oil, wherein is selected from the group consisting of chlorophenyl-modified silicone oil and fluorine-modified silicone oil Item 4. The multicolor image forming method according to Item 1. An electrostatic latent image is formed on each surface, and a plurality of image carriers arranged side by side;
A plurality of developing means for forming predetermined color toner images respectively on the plurality of image carriers;
A conveying unit that circulates to convey a transfer material to each of the plurality of image carriers;
A plurality of transfer means for sequentially transferring the color toner images on the image carrier onto the transfer material conveyed to the image carrier by the transport means;
A tandem-type multicolor image forming apparatus comprising a fixing unit that thermally fixes a toner image transferred onto the transfer material,
Each color toner used in the plurality of developing means, formed SQLDESC_BASE_TABLE_NAME This added 0.02 part by weight or more 0.5 parts by weight of silicone oil relative to 100 parts by weight of the toner particles, a plurality of image carriers that are the parallel The amount of silicone oil added to the toner particles of the color toner that develops the electrostatic latent image on the image carrier disposed downstream of the body develops the electrostatic latent image on the image carrier disposed upstream. silicone oil added amount or more with respect to the toner particles of the color toner is disposed most upstream end silicone oil amount and the toner particles of the color toner for developing an electrostatic latent image arranged image carrier on the most downstream side A multicolor image forming apparatus characterized in that the amount of silicone oil added to the toner particles of the color toner for developing the electrostatic latent image on the image bearing member is the smallest.   The plurality of transfer units respectively corresponding to the plurality of image carriers arranged side by side are contact-type copying units arranged so as to press the transfer material against the corresponding image carriers. Item 4. The multicolor image forming apparatus according to Item 3.

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