JP2022026473A - Image forming apparatus - Google Patents

Abstract

To obtain sufficient adhesive strength while reducing heat quantity to be supplied to a sheet in an adhering step.SOLUTION: An image forming apparatus comprises: image forming means which forms a toner image (53c) on a sheet using printing toner and applies a powder adhesive (Tn) to the sheet; fixing means which heats the toner image formed on the sheet by the image forming means to fix the image to the sheet; folding means (31) which folds the sheet that has passed through the fixing means; and adhering means (32) which heats the sheet folded by the folding means to adhere the folded sheet to each other with the powder adhesive. The folding means has rotating bodies (31a, 31b, 31c, 31d) which contact with the sheet to rotate, the ten-point average roughness Rzjis of the surface of the rotating body is equal to or more than 10 μm.SELECTED DRAWING: Figure 10

Description

The present invention relates to an image forming apparatus that forms an image on a sheet.

Conventionally, when creating documents that require confidentiality and sealing, such as pay slips, prepare preprinted paper coated with adhesive in advance and print variable data on the preprinted paper. , A sealing process was performed as a post-treatment. This method takes time to produce preprinted paper that requires the application of an adhesive, and is inefficient in applications where the required quantity is small.

In Patent Document 1, an image that outputs a document sealed by one device while using plain paper by using an adhesive toner (powder adhesive) in addition to an image forming toner by using an electrophotographic process. We are proposing a forming device. The adhesive toner is designed to melt at a lower temperature than the image forming toner, and is applied to a sheet as a recording medium by being transferred by an electrophotographic process like the image forming toner. After that, the sheets are folded so that the surfaces on which the adhesive toner images are formed face each other, and finally the sheets are adhered by heating with the adhesive surfaces of the sheets in close contact with each other via the adhesive toner. Since this method completes the printing process and the bonding process with one image forming apparatus, it is efficient even in applications where the required quantity is small. Further, the method of adhering by heating and melting the adhesive does not require a strong pressure, and is advantageous for miniaturization and noise reduction of the device.

Japanese Unexamined Patent Publication No. 2006-171607

As described in the above document, when the printing step and the bonding step are performed in one image forming device, a heating device for fixing the image and a heating device for bonding the sheets are used in combination. As a heating element of a heating device, a heating resistor, a halogen lamp, an induction heating mechanism, and the like are known, but since all of them are elements that consume a large amount of power among image forming devices, power saving is required. Further, if the temperature of a heating member such as a heating roller is too high in the bonding step, there is a concern that an image defect called hot offset may occur in which the printed image that should have been fixed is remelted and adheres to the sheet.

Therefore, an object of the present invention is to obtain sufficient adhesive strength while reducing the amount of heat supplied to the sheet in the adhesive process.

The image forming apparatus according to one aspect of the present invention is formed on a sheet by an image forming means for forming a toner image on a sheet using a printing toner and applying a powder adhesive to the sheet, and the image forming means. The fixing means for heating and fixing the toner image to the sheet, the folding means for folding the sheet that has passed through the fixing means, and the sheet folded by the folding means are heated, and the sheets are bonded with the powder adhesive. An image forming apparatus comprising an adhesive means, wherein the folding means has a rotating body that rotates in contact with a sheet, and the ten-point average roughness Rzjis of the surface of the rotating body is 10 μm or more. , Characterized by that.

The image forming apparatus according to another aspect of the present invention is an image forming means for forming a toner image on a sheet using a printing toner and applying a powder adhesive to the sheet, and the image forming means for forming the sheet. A fixing means for heating and fixing the formed toner image to the sheet, a folding means for folding the sheet that has passed through the fixing means, and a sheet folded by the folding means for heating the sheet with the powder adhesive. An image forming apparatus including an adhesive means for adhering, wherein the folding means has a rotating body that rotates in contact with a sheet, and the rotating body has a hollow structure.

The image forming apparatus according to still another aspect of the present invention is an image forming means for forming a toner image on a sheet using a printing toner and applying a powder adhesive to the sheet, and the sheet by the image forming means. The fixing means for heating and fixing the toner image formed on the sheet to the sheet, the folding means for folding the sheet that has passed through the fixing means, and the sheet folded by the folding means for heating the sheet with the powder adhesive. An image forming apparatus comprising an adhesive means for adhering the folding means and a cover portion provided above the folding means and the adhesive means and covering the folding means and the adhesive means when viewed in the direction of gravity. The portion is provided with an opening that communicates the space above the image forming apparatus and the internal space of the image forming apparatus, and the ratio of the opening area of the opening to the area of the cover portion as viewed in the direction of gravity. Is 5% or less.

The image forming apparatus according to still another aspect of the present invention is an image forming means for forming a toner image on a sheet using a printing toner and applying a powder adhesive to the sheet, and the sheet by the image forming means. The fixing means for heating and fixing the toner image formed on the sheet to the sheet, the folding means for folding the sheet that has passed through the fixing means, and the sheet folded by the folding means for heating the sheet with the powder adhesive. An image forming apparatus comprising an adhesive means for adhering the adhesive means, wherein the sheet conveying speed of the adhesive means is slower than the sheet conveying speed of the fixing means, and the folding means is faster than the sheet conveying speed of the adhesive means. After starting to convey the sheet toward the adhesive means at the sheet transfer speed, the sheet transfer speed is reduced to the sheet transfer speed of the adhesive means before the tip of the sheet in the sheet transfer direction reaches the adhesive means. It is characterized by that.

The image forming apparatus according to still another aspect of the present invention is an image forming means for forming a toner image on a sheet using a printing toner and applying a powder adhesive to the sheet, and the sheet by the image forming means. The fixing means for heating and fixing the toner image formed on the sheet to the sheet, the folding means for folding the sheet that has passed through the fixing means, and the sheet folded by the folding means for heating the sheet with the powder adhesive. An image forming apparatus comprising an adhesive means for adhering the above, wherein the powder adhesive is a crystalline material compatible with the binder resin and is heated by the fixing means. The surface temperature of the powder adhesive, which contains a crystalline material that melts into a sheet and is heated by the fixing means after being applied to the sheet, is higher than the crystallization temperature at the time of lowering the temperature of the crystalline material. The folding means folds the sheet.

According to the present invention, sufficient adhesive strength can be obtained while reducing the amount of heat supplied to the sheet in the adhesive process.

The schematic diagram of the image forming apparatus which concerns on Example 1. FIG. The figure for demonstrating the attachment of the post-processing unit to the apparatus main body of the image forming apparatus which concerns on Example 1. FIG. The figure which shows the transport path of the sheet in the image forming apparatus which concerns on Example 1. FIG. The figure which shows the other transfer path of the sheet in the image forming apparatus which concerns on Example 1. FIG. Figures (a to f) for explaining the contents of the folding process which concerns on Example 1. FIG. The perspective view which shows the appearance of the image forming apparatus which concerns on Example 1. FIG. Figures (a to c) illustrate the deliverables output by the image forming apparatus according to the first embodiment. The schematic diagram of the process cartridge which concerns on Example 1. FIG. The schematic diagram of the 1st fixer which concerns on Example 1. FIG. FIG. (A) for explaining the image defect generated in the bonding step and the schematic view (b) of the second fixing device according to the first embodiment. The figure (a) which shows the time change of the temperature of a powder adhesive, and the figure (b) which shows the relationship of the heater temperature at the time of strong adhesion required for strong adhesion. The figure which shows the result of having measured the powder adhesive using the differential scanning calorimetry apparatus. Figures (a to c) for explaining changes in the powder adhesive in the fixing step. The figure (a, b) for demonstrating the change of the powder adhesive in a folding process.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

(Overall equipment configuration)
First, the overall configuration of the image forming apparatus will be described with reference to FIGS. 1, 2, and 6. FIG. 1 shows a cross-sectional configuration of an image forming apparatus 1 including an image forming apparatus main body (hereinafter referred to as an apparatus main body 10) according to the first embodiment and a post-processing unit 30 connected to the apparatus main body 10. It is a schematic diagram. The image forming apparatus 1 is an electrophotographic image forming apparatus (electrophotograph system) composed of an apparatus main body 10 provided with an electrophotographic printing mechanism and a post-processing unit 30 as a sheet processing apparatus.

FIG. 6 is a perspective view showing the appearance of the image forming apparatus 1. The post-processing unit 30 is mounted on the upper part of the apparatus main body 10. The image forming apparatus 1 has a sheet cassette 8 in the lower portion, a tray 20 that can be opened and closed on the right side surface portion, and a first discharge tray 13 on the upper surface portion.

First, the internal configuration of the apparatus main body 10 will be described. As shown in FIG. 1, the apparatus main body 10 includes a sheet cassette 8 as a sheet storage unit for storing a sheet P as a recording medium, an image forming unit 1e as an image forming means, and a first fixing device as a fixing means. 6 and a housing 19 for accommodating these are provided. The apparatus main body 10 has a printing function of forming a toner image on a sheet P fed from a sheet cassette 8 by an image forming unit 1e and producing a printed matter subjected to a fixing process by a first fixing device 6. As the sheet P which is a recording medium, for example, paper is used.

The sheet cassette 8 is inserted into the housing 19 at the lower part of the apparatus main body 10 so as to be retractable, and houses a large number of sheets P. The sheet P housed in the sheet cassette 8 is fed from the sheet cassette 8 by a feeding member such as a feeding roller, and is conveyed by the conveying roller 8a in a state of being separated one by one by a pair of separating rollers. It is also possible to feed the sheets set in the open tray 20 (FIG. 6) one by one.

The image forming unit 1e is a tandem type electrophotographic unit including four process cartridges 7n, 7y, 7m, 7c, a scanner unit 2, and a transfer unit 3. The process cartridge is a unit in which a plurality of parts responsible for the image forming process are integrally exchangeable. The apparatus main body 10 is provided with a cartridge support portion 9 supported by the housing 19, and each process cartridge 7n, 7y, 7m, 7c is a mounting portion 9n, 9y, 9m provided on the cartridge support portion 9. It is detachably attached to 9c. The cartridge support portion 9 may be a tray member that can be pulled out from the housing 19.

Each process cartridge 7n, 7y, 7m, 7c has a substantially common configuration except for the types of powder contained in the four powder accommodating portions 104n, 104y, 104m, 104c. That is, each process cartridge 7n, 7y, 7m, 7c includes a photosensitive drum 101 as an image carrier, a charging roller 102 as a charging device, a powder accommodating portion 104n, 104y, 104m, 104c for accommodating powder, and powder. It includes a developing roller 105 for developing using a body.

Of the four powder accommodating portions, the three powder accommodating portions 104y, 104m, 104c on the right side of the figure are toners (first powder, powder developer) for forming a visible image on the sheet P. As a result, yellow, magenta, and cyan printing toners Ty, Tm, and Tc are contained, respectively. On the other hand, the powder adhesive Tn, which is a toner (second powder) for performing an adhesive treatment after printing, is contained in the powder accommodating portion 104n on the leftmost side in the drawing. The powder accommodating portions 104y, 104m, and 104c are all examples of the first accommodating portion for accommodating the printing toner, and the powder accommodating portion 104n is an example of the second accommodating portion for accommodating the powder adhesive. Further, the process cartridges 7y, 7m, and 7c are all examples of the first process unit that forms a toner image using printing toner, and the process cartridge 7n forms an image of a powder adhesive with a predetermined coating pattern. This is an example of the second process unit.

In this embodiment, when printing a black image such as text, it is represented by process black on which yellow (Ty), magenta (Tm), and cyan (Tc) toners are superimposed. However, for example, a fifth process cartridge using black printing toner may be added to the image forming unit 1e so that the black image can be expressed by the black printing toner. Not limited to this, the type and number of printing toners can be changed according to the application of the image forming apparatus 1.

The scanner unit 2 is arranged below the process cartridges 7n, 7y, 7m, 7c and above the sheet cassette 8. The scanner unit 2 is the exposure means of the present embodiment in which the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, 7c is irradiated with the laser beam G to write an electrostatic latent image.

The transfer unit 3 includes a transfer belt 3a as an intermediate transfer body (secondary image carrier). The transfer belt 3a is a belt member wound around the secondary transfer inner roller 3b and the tension roller 3c, and faces the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, 7c on the outer peripheral surface. On the inner peripheral side of the transfer belt 3a, the primary transfer roller 4 is arranged at a position corresponding to each photosensitive drum 101. Further, a secondary transfer roller 5 as a transfer means is arranged at a position facing the secondary transfer inner roller 3b. The transfer nip 5N between the secondary transfer roller 5 and the transfer belt 3a is a transfer unit (secondary transfer unit) on which the toner image is transferred from the transfer belt 3a to the sheet P.

The first fixing device 6 is arranged above the secondary transfer roller 5. FIG. 9 is a detailed view of the first fuser 6. The first fixing device 6 is a pressure roller 6b that forms a fixing nip 6N together with a cylindrical fixing film (endless belt) 6a, a heater 6a1 that contacts the inner surface of the fixing film 6a, and a heater 6a1 via the fixing film 6a. And have. The fixing film 6a and the pressure roller 6b function as a pair of rotating bodies (first pair of rotating bodies) that rotate by sandwiching the sheet P. The fixing film 6a has a base layer having a thickness of 30 to 70 μm, which is made of a heat-resistant resin such as polyimide, polyamide, PEEK, or a metal such as stainless steel. The fixing film 6a is provided with an elastic layer having a thickness of 0.1 to 1 mm made of silicone rubber or the like and a release layer having a thickness of 5 to 30 μm made of a fluororesin such as PFA or PTFE on the base layer. .. The surface layer of the fixing film 6a becomes a surface in contact with the molten toner and the powder adhesive, and the surface of the toner after the fixing step is leveled according to the shape of the surface of the fixing film 6a as described later.

The pressure roller 6b is a mold release made of a core metal 6b1 made of iron, aluminum or the like, an elastic layer 6b2 having a thickness of 2 to 4 mm made of silicone rubber or the like, and a fluororesin such as PFA or PTFE provided on the outermost surface. With a layer.

The heater 6a1 as a heating means (first heating means) insulates a thin plate-shaped substrate 6a11 mainly made of ceramics made of alumina or the like from a heat generating resistor 6a12 such as Ag / Pd (silver-palladium) that generates heat by energization. It has a protective layer (glass layer in this embodiment) 6a13. A temperature detecting element 6a2 such as a thermistor is in contact with the substrate 6a11, and is connected to the CPU 6a3 as a control unit mounted on the image forming apparatus 1. The heater 6a1 raises the temperature by supplying power to the heat generation resistor 6a12. The temperature rise is detected by the temperature detection element 6a2, and the CPU 6a3 controls the energization of the heat generation resistor 6a12 via the triac 6a4. For example, when the detection temperature of the temperature detection element 6a2 is lower than the predetermined set temperature, the amount of electric power supplied to the heat generating resistor 6a12 is increased so that the heater 6a1 rises, and when the temperature is higher than the set temperature, the amount of electric power is decreased so as to lower the temperature. By controlling, the heater 6a1 is kept at a constant temperature.

The heater 6a1 is held by a holding member 6a5 made of a heat-resistant resin such as LCP (liquid crystal polymer). The holding member 6a5 also has a guide function for guiding the rotation of the fixing film 6a. The holding member 6a5 is subjected to a force in a direction approaching the pressure roller 6b from a spring (not shown) attached to the metal stay 6a6. The pressurizing roller 6b is pressed in the heater 6a1 direction via the fixing film 6a at a total pressure of 10 to 30 kgf by a pressurizing means such as a spring member (not shown). As a result, a fixing nip 6N having a width of 5 to 11 mm in the sheet transport direction is formed between the pressure roller 6b and the heater 6a1 and the holding member 6a5 constituting the nip portion forming unit.

The pressurizing roller 6b receives power from a motor (not shown) and rotates in the direction of arrow r1 in FIG. Then, as the pressure roller 6b rotates, the fixing film 6a is driven and rotated. The sheet P supporting the unfixed toner image is together with the fixing film 6a while the surface (image surface) supporting the toner image of the sheet P and the powder adhesive Tn in the fixing nip 6N is brought into close contact with the outer surface of the fixing film 6a. The fixing nip 6N is transported in the sheet transport direction. As a feature of this configuration, the heat capacity of the fixing film and the heater is particularly small, and the holding member 6a5 is also made of a material having high heat insulating properties, so that the surface of the fixing film 6a can be heated to a high temperature faster with a small amount of heat supply. Is.

The housing 19 is provided with a discharge port 12 (first discharge port) which is an opening for discharging the sheet P from the apparatus main body 10, and a discharge unit 34 is arranged in the discharge port 12. .. The discharge unit 34, which is the discharge means of the present embodiment, uses a so-called triple roller having a first discharge roller 34a, an intermediate roller 34b, and a second discharge roller 34c. Further, a switching guide 33, which is a flap-shaped guide for switching the transport path of the sheet P, is provided between the first fixing device 6 and the discharging unit 34. The switching guide 33 is rotatable around the shaft portion 33a so that the tip 33b reciprocates in the direction of the arrow c in the drawing.

The apparatus main body 10 is provided with a mechanism for performing double-sided printing. A motor (not shown) is connected to the discharge unit 34 so that the intermediate roller 34b can rotate in the forward and reverse directions. Further, a double-sided transport path 1r is provided as a transport path connected in a loop to the main transport path 1 m. The sheet P whose image is formed on the first surface while passing through the main transport path 1 m is sandwiched and transported by the first discharge roller 34a and the intermediate roller 34b by the switching guide 33 (broken line position) rotated clockwise. .. After the rear end of the sheet P in the traveling direction passes through the switching guide 33, the intermediate roller 34b reverses as the switching guide 33 rotates counterclockwise (solid line position), and the sheet P is reversely conveyed to the double-sided transfer path 1r. Will be done. Then, while the sheet P passes through the main transport path 1 m again with the front and back reversed, an image is formed on the second surface of the sheet P. The sheet P after double-sided printing is guided by the switching guide 33 (solid line position) rotated counterclockwise, sandwiched and conveyed by the intermediate roller 34b and the second discharge roller 34c, and discharged from the apparatus main body 10.

Further, the transfer path passing through the transfer roller 8a, the transfer nip 5N, and the fixing nip 6N in the apparatus main body 10 constitutes a main transfer path 1 m in which an image is formed on the sheet P. The main transport path 1 m is horizontal to the image forming unit 1e when viewed from the main scanning direction at the time of image formation (the width direction of the sheet perpendicular to the transport direction of the sheet transported along the main transport path 1 m). It extends from the bottom to the top through one side. In other words, the apparatus main body 10 of this embodiment is a so-called vertical transport type (vertical pass type) printer in which the main transport path 1 m extends in a substantially vertical direction. When viewed in the vertical direction, the first discharge tray 13, the intermediate pass 15, and the sheet cassette 8 overlap each other. Therefore, the moving direction of the sheet when the discharging unit 34 discharges the sheet P in the horizontal direction is opposite to the moving direction of the sheet when the sheet P is fed from the sheet cassette 8 in the horizontal direction.

Further, from the viewpoint of FIG. 1 (when viewed in the main scanning direction at the time of image formation), the horizontal occupied range of the main body portion of the post-processing unit 30 excluding the second discharge tray 35 is the occupied range of the apparatus main body 10. It is preferable that it fits in. By accommodating the post-processing unit 30 in the space above the apparatus main body 10 in this way, the sheet transport path in the case of performing adhesive printing is compared with the arrangement in which the apparatus main body 10 and the post-processing unit 30 are arranged side by side (the first described later). 2 routes) can be designed short. As a result, the sheet P discharged from the apparatus main body 10 through the first fixing device 6 is immediately introduced into the post-treatment unit 30, and the heat of the sheet P heated in the fixing step is released as much as possible. You can enter the folding process and the bonding process without any. As will be described later, by allowing the sheet P to retain the heat supplied in the fixing process as much as possible, it is possible to reduce the energy consumption in the bonding process.

(Post-processing unit)
As shown in FIG. 2, the post-processing unit 30 is attached to the upper part of the apparatus main body 10. In the post-processing unit 30, the folding device 31 as a folding means and the second fixing device 32 as an adhesive means (second fixing means) are housed in a housing (second housing) 39 and integrated. It is a post-processing unit that has been used.

The configuration of the second fuser 32 in this embodiment is the same as that of the first fuser 6 as shown in FIG. 10 (b). The sheet P, which has a tubular heating film (endless belt) 32b and a pressure roller 32a and is folded by the folding device 31, is subjected to an adhesive nip 32N (second fixing) which is a nip portion of the heating film 32b and the pressure roller 32a. Nip) to hold and transport. The heating film 32b and the pressure roller 32a function as a pair of rotating bodies (second pair of rotating bodies) that rotate while sandwiching the sheet P. Similar to the first fuser 6, a heater 32b1 and a temperature detecting element 32b2 as heating means are provided on the inner surface side of the heating film 32b. The sheet P is sandwiched and conveyed by the adhesive nip 32N by the driven rotation of the heating film 32b driven by the pressure roller 32a that rotates in the direction of the arrow r2. In the process, the sheet P is heated and pressurized, so that the powder adhesive Tn applied to the sheet P is softened again, and the sheet P is adhered in a folded state.

Further, the post-processing unit 30 is provided with a first discharge tray 13 that rotatably holds the tray switching guide 13a, an intermediate path 15, and a second discharge tray 35. The first discharge tray 13 is provided on the upper surface of the post-processing unit 30, and is located on the upper surface (FIG. 1) of the entire image forming apparatus 1. The functions of each part included in the post-processing unit 30 will be described later.

Further, as shown in FIG. 6, the internal space of the image forming apparatus 1 and the upper part of the image forming apparatus 1 are formed in the top surface portion (region 39a shown by the dotted line) of the cover member covering the upper part of the second fixing device 32 which is a heat source. Three 4 mm × 150 mm slits are formed as an opening 38 that communicates with the space. The area of the region 39a seen in the direction of gravity is 460 mm × 160 mm. The aperture ratio of the opening 38 with respect to the top surface of the cover member (the ratio of the total opening area of the slits to the area of the region 39a) is about 2.4%. The aperture ratio of the opening 38 is preferably about 0.1% to 5%. The opening 38 is designed to reduce the amount of air discharged in the vicinity of the fuser and to allow warm air to easily stay in the region below the region 39a, as compared with the fuser used for heat fixing of a normal image in an image forming apparatus. There is. The reason will be explained below.

It is known that water evaporates from the sheet to generate water vapor around the normal fuser, and the air around the fuser is designed so that it is easily discharged as a measure against dew condensation. However, in the case of the second fixing device 32 according to the present embodiment, since water is released from the sheet when the fixing step (first heating step) by the first fixing device 6 is completed, adhesion by the second fixing device 32 is performed. It usually does not occur that a large amount of water vapor is generated after the step (second heating step). Therefore, the risk of dew condensation is lower in the second fuser 32 than in the first fuser 6, and even if the opening ratio of the top surface portion (region 39a) of the cover member is lowered, no problem occurs.

Then, by lowering the opening ratio of the top surface portion of the cover member, the air warmed by the second fixing device 32 can be retained inside the post-treatment unit 30 and reused for warming the folding device 31. can. As will be described later, if the temperature of the roller member in contact with the sheet in the folding device 31 is high, it is advantageous in reducing the energy consumption in the bonding process.

The post-processing unit 30 has a positioning portion (for example, a convex shape that engages with the concave portion of the housing 19) for positioning the housing 39 with respect to the housing 19 (first housing) of the apparatus main body 10. It is provided. Further, the post-processing unit 30 is provided with a drive source and a control unit separate from the device main body 10, and the connector 36 of the post-processing unit 30 and the connector 37 of the device main body 10 are coupled to the device main body 10. It is electrically connected. As a result, the post-processing unit 30 is in a state of operating based on a command from the control unit provided in the device main body 10 by using the electric power supplied through the device main body 10.

(Process cartridge)
As described above, the process cartridges 7n, 7y, 7m, and 7c have substantially the same configuration except for the types of powder contained in the four powder accommodating portions 104n, 104y, 104m, 104c. There is. Here, the process cartridge 7n will be described as a representative. FIG. 8 is a cross-sectional view showing a schematic configuration of the process cartridge 7n. The process cartridge 7n includes a photoconductor unit CC including a photosensitive drum 101 and the like, and a developing unit DT including a developing roller 105 and the like.

A photosensitive drum 101, which is an electrophotographic photosensitive member (image carrier) formed in a drum shape, is rotatably attached to the photoconductor unit CC via a bearing (not shown). Further, the photosensitive drum 101 is rotationally driven in the clockwise direction (arrow w) in the figure during an image forming operation by receiving a driving force of a motor as a driving means (driving source) (not shown). Further, in the photoconductor unit CC, a charging roller 102 for charging the photosensitive drum 101 and a cleaning member 103 are arranged around the photosensitive drum 101.

The developing unit DT is provided with a developing roller 105 as a developing agent carrier that comes into contact with the photosensitive drum 101 and rotates in the counterclockwise direction (arrow d) in the drawing. The developing roller 105 and the photosensitive drum 101 rotate so that their surfaces move in the same direction at the facing portion (contact portion).

Further, the developing unit DT is arranged with a developing agent supply roller (hereinafter, simply referred to as “supply roller 106”) as a developing agent supplying member that rotates in the clockwise direction (arrow e) in the drawing. The supply roller 106 and the developing roller 105 rotate so that their surfaces move in the same direction at the facing portion (contact portion). The supply roller 106 supplies a powder adhesive (printing toner in the case of process cartridges 7y, 7m, 7c) onto the developing roller 105. At the same time, the supply roller 106 acts to strip the powder adhesive (printing toner in the case of the process cartridges 7y, 7m, 7c) remaining on the developing roller 105 from the developing roller 105. Further, the developing unit DT is used as a developing agent regulating member that regulates the layer thickness of the powder adhesive (printing toner in the case of process cartridges 7y, 7m, 7c) supplied on the developing roller 105 by the supplying roller 106. The developing blade 107 of the above is arranged.

The powder adhesive (printing toner in the case of process cartridges 7y, 7m, 7c) is stored as powder in the powder accommodating portion 104n. Further, a transport member 108 rotatably supported is provided in the powder accommodating portion 104n. The transport member 108 rotates in the clockwise direction (arrow f) in the drawing to agitate the powder stored in the powder accommodating portion 104n, and the developing chamber 109 provided with the developing roller 105 and the supply roller 106. Transport the powder to.

Here, it is also possible to separate the photoconductor unit CC and the developing unit DT into a photoconductor unit cartridge and a developing unit cartridge so that they can be attached to and detached from the image forming apparatus main body. Further, apart from the process cartridge having the photoconductor and the developer carrier, it is also possible to have only the powder accommodating portion 104 and the transport member 108, and to configure the powder cartridge as a detachable powder cartridge to the main body of the apparatus.

(Printing toner)
As the printing toners Tm, Tc, and Ty of this embodiment, conventionally known printing toners can be used. Among them, a printing toner using a thermoplastic resin as a binder resin is preferable. The thermoplastic resin is not particularly limited, and those used for conventional printing toners such as polyester resin, vinyl resin, acrylic resin, and styrene acrylic resin can be used. A plurality of these resins may be contained. Among them, a printing toner using a styrene acrylic resin is more preferable. Further, the printing toner (printing developer) may contain a colorant, a magnetic substance, a charge control agent, a wax, and an external additive.

(Powder adhesive)
Further, as the powder adhesive Tn of this example, a powder adhesive containing a thermoplastic resin can be used as the binder resin. The thermoplastic resin is not particularly limited, and is not particularly limited, such as polyester resin, vinyl resin, acrylic resin, styrene acrylic resin, polyethylene, polypropylene, polyolefin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, etc. Examples of the known thermoplastic resin of the above. A plurality of these resins may be contained.

Further, the powder adhesive Tn preferably further contains a crystalline material having compatibility with the binder resin. Examples of the crystalline material include known crystalline resins such as crystalline polyester resin and crystalline vinyl resin, ester wax which is an ester of alcohol and acid, and hydrocarbon wax such as paraffin wax. Known waxes can be used. A crystalline resin and wax may be used in combination. These crystalline materials act as a plasticizer that imparts plasticity to the powder adhesive Tn when heated. That is, the crystalline material dispersed in the binder resin in a crystalline state at room temperature instantly melts when the powder adhesive Tn is heated and is compatible with the binder resin, thereby causing deformation of the powder adhesive Tn. It has the effect of facilitating.

Further, the powder adhesive Tn may contain a colorant. As the colorant, known colorants such as a black colorant, a yellow colorant, a magenta colorant, and a cyan colorant can be used. The content of the colorant in the powder adhesive is preferably 1.0% by mass or less, and more preferably 0.1% by mass or less. Further, the powder adhesive Tn may contain a magnetic substance, a charge control agent, a wax, and an external additive.

In order to form an adhesive portion with a powder adhesive on the sheet P by using an electrophotographic method, the weight average particle size of the powder adhesive Tn is preferably 5.0 μm or more and 30 μm or less, preferably 6.0 μm or more. It is more preferably 20 μm or less. A printing toner may be used as the powder adhesive Tn as long as it satisfies the adhesiveness.

(Manufacturing example of powder adhesive)
Hereinafter, a method for producing the powder adhesive Tn will be illustrated. The powder adhesive Tn according to this production example contains an ester wax and a hydrocarbon wax as a crystalline material having compatibility with a binder resin (styrene-butyl acrylate copolymer and polyester resin).

First, the following materials were prepared.
-Styrene 75.0 parts-n-butyl acrylate 25.0 parts-Polyester resin 4.0 parts (weight average molecular weight (Mw) 20000, glass transition temperature (Tg) 75 ° C., acid value 8.2 mgKOH / g amorphous Sexual polyester resin)
・ Ethylene glycol distearate 14.0 parts (ester wax obtained by esterifying ethylene glycol and stearic acid)
・ Hydrocarbon wax (HNP-9, manufactured by Nippon Seiro) 2.0 parts ・ Divinylbenzene 0.5 parts

The mixture of the above materials was kept warm at 60 ° C., and T.I. K. Using a homomixer (manufactured by Tokushu Kagaku Kogyo Co., Ltd.), the mixture was stirred at 500 rpm and uniformly dissolved to prepare a polymerizable monomer composition.

On the other hand, 850.0 parts of 0.10 mol / L-Na ₃ PO ₄ aqueous solution and 8.0 parts of 10% hydrochloric acid were added to a container equipped with a high-speed stirrer Clairemix (manufactured by M-Technique) to increase the rotation speed. The temperature was adjusted to 15000 rpm and heated to 70 ° C. To this, 127.5 parts of a 1.0 mol / L-CaCl ₂ aqueous solution was added to prepare an aqueous medium containing a calcium phosphate compound.

After putting the above-mentioned polymerizable monomer composition into an aqueous medium, 7.0 parts of T-butylperoxypivalate as a polymerization initiator is added, and the mixture is prepared for 10 minutes while maintaining the rotation speed of 15,000 rpm. Grained. Then, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and the mixture was reacted at 70 ° C. for 5 hours while refluxing, and then the liquid temperature was set to 85 ° C., and the reaction was further carried out for 2 hours.

After completion of the polymerization reaction, the obtained slurry was cooled, and hydrochloric acid was further added to the slurry to adjust the pH to 1.4, and the mixture was stirred for 1 hour to dissolve the calcium phosphate salt. Then, it was washed with three times the amount of water of the slurry, filtered, dried, and then classified to obtain powder adhesive particles.

Then, silica fine particles (number average particle size of primary particles: 10 nm, BET) treated with dimethyl silicone oil (20% by mass) as an external additive to hydrophobicize 100.0 parts of the powder adhesive particles. Specific surface area: 170 m ² / g) 2.0 parts were added. Then, the powder adhesive particles to which the silica fine particles were added were mixed with Mitsui Henchel Mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.) at 3000 rpm for 15 minutes to obtain a powder adhesive. The weight average particle size of the obtained powder adhesive was 6.8 μm.

(Measurement method of glass transition temperature (Tg))
The glass transition temperature (Tg) of the powder adhesive Tn can be measured using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments). The melting point of indium and zinc is used for temperature correction of the device detection unit, and the heat of fusion of indium is used for the correction of calorific value.

Specifically, 1 mg of a sample is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference. Using the modulation measurement mode, the measurement is performed in the range of 0 ° C. to 100 ° C. at a heating rate of 1 ° C./min and a temperature modulation condition of ± 0.6 ° C./60 seconds. Since the specific heat change is obtained in the heating process, the intersection of the line between the midpoint of the baseline before and after the specific heat change and the differential thermal curve is defined as the glass transition temperature (Tg). The glass transition temperature (Tg) of the obtained powder adhesive Tn was 52 ° C.

(Manufacturing example of printing toner)
Next, a method for manufacturing the printing toners Ty, Tm, and Tc will be illustrated. First, the following materials were prepared.
・ Styrene 60.0 parts ・ Colorant 6.5 parts (CI Pigment Blue 15: 3, manufactured by Dainichiseika Co., Ltd.)

The above material was put into an attritor (manufactured by Mitsui Miike Machinery Co., Ltd.) and further dispersed using zirconia particles having a diameter of 1.7 mm at 220 rpm for 5 hours to obtain a pigment dispersion liquid.

In addition, the following materials were prepared.
・ Styrene 15.0 parts ・ n-butyl acrylate 25.0 parts ・ Polyester resin 4.0 parts (weight average molecular weight (Mw) 20000, glass transition temperature (Tg) 75 ° C., acid value 8.2 mgKOH / g polyester resin )
・ Behenic behenic acid 12.0 parts (ester wax obtained by esterifying behenic acid and behenic alcohol)
・ 0.5 part of divinylbenzene

The above materials were mixed and added to the pigment dispersion. The resulting mixture was kept warm at 60 ° C. to T.I. K. Using a homomixer (manufactured by Tokushu Kagaku Kogyo Co., Ltd.), the mixture was stirred at 500 rpm and uniformly dissolved and dispersed to prepare a polymerizable monomer composition.

On the other hand, 850.0 parts of 0.10 mol / L-Na ₃ PO ₄ aqueous solution and 8.0 parts of 10% hydrochloric acid were added to a container equipped with a high-speed stirrer Clairemix (manufactured by M-Technique) to increase the rotation speed. The temperature was adjusted to 15000 rpm and heated to 70 ° C. To this, 127.5 parts of a 1.0 mol / L-CaCl ₂ aqueous solution was added to prepare an aqueous medium containing a calcium phosphate compound.

After putting the above-mentioned polymerizable monomer composition into an aqueous medium, 7.0 parts of T-butylperoxypivalate as a polymerization initiator is added, and the mixture is prepared for 10 minutes while maintaining the rotation speed of 15,000 rpm. Grained. Then, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and the mixture was reacted at 70 ° C. for 5 hours while refluxing, and then the liquid temperature was set to 85 ° C., and the reaction was further carried out for 2 hours.

After completion of the polymerization reaction, the obtained slurry was cooled, and hydrochloric acid was further added to the slurry to adjust the pH to 1.4, and the mixture was stirred for 1 hour to dissolve the calcium phosphate salt. Then, it was washed with three times the amount of water of the slurry, filtered, dried, and then classified to obtain toner particles.

After that, silica fine particles (number average particle size of primary particles: 10 nm, BET specific surface area) were hydrophobically treated with dimethyl silicone oil (20% by mass) as an external additive with respect to 100.0 parts of toner particles. : 170 m ² / g) 2.0 parts were added. Then, the toner particles to which silica fine particles were added were mixed with Mitsui Henschel Mixer (manufactured by Mitsui Miike Machinery Co., Ltd.) at 3000 rpm for 15 minutes to obtain toner. The weight average particle size of the obtained printing toner was 6.5 μm.

(Measuring method of weight average particle size)
The weight average particle diameters of the printing toners Ty, Tm, Tc and the powder adhesive Tn are calculated as follows. As the measuring device, a precision particle size distribution measuring device “Coulter Counter MulDisizer 3” (registered trademark, manufactured by Beckman Coulter) equipped with a 100 μm aperture tube by the pore electric resistance method is used. For the setting of measurement conditions and the analysis of measurement data, the attached dedicated software "Beckman Coulter MulSizer 3 Version 3.51" (manufactured by Beckman Coulter) is used. The measurement is performed with 25,000 effective measurement channels.

As the electrolytic aqueous solution used for the measurement, one in which special grade sodium chloride is dissolved in ion-exchanged water so that the concentration becomes 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter) can be used.

Before performing measurement and analysis, set the dedicated software as follows. On the "Change standard measurement method (SOM)" screen of the dedicated software, set the total count number in the control mode to 50,000 particles, measure once, and set the Kd value to "standard particles 10.0 μm" (Beckman Coulter). The value obtained by using (manufactured by) is set. By pressing the "threshold / noise level measurement button", the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, and the electrolyte to ISOTON II, and check "Flash of aperture tube after measurement". On the "Pulse to particle size conversion setting" screen of the dedicated software, set the bin spacing to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

The specific measurement method is as follows.
(1) Put 200 mL of the electrolytic aqueous solution in a 250 mL round bottom beaker made of glass exclusively for MulSizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "flash of the aperture tube" function of the dedicated software.
(2) Put 30 mL of the electrolytic aqueous solution in a 100 mL flat-bottomed beaker made of glass. Among them, as a dispersant, "Contaminone N" (a 10% by mass aqueous solution of a neutral detergent for cleaning a pH 7 precision measuring instrument consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, Wako Pure Chemical Industries, Ltd. Is diluted 3 times by mass with ion-exchanged water, and 0.3 mL of the diluted solution is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with the phase shifted by 180 degrees, and an ultrasonic disperser "Ultrasonic Dispersion System TeTora 150" (manufactured by Nikkei Bios) with an electrical output of 120 W is prepared. Put 3.3 L of ion-exchanged water in the water tank of the ultrasonic disperser, and add 2 mL of contaminationon N to this water tank.
(4) The beaker of (2) above is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic solution in the beaker is maximized.
(5) With the electrolytic aqueous solution in the beaker of (4) above being irradiated with ultrasonic waves, toner or powder adhesive is added little by little to the electrolytic aqueous solution so as to be 10 mg, and dispersed. Then, the ultrasonic dispersion processing is continued for another 60 seconds. For ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10 ° C. or higher and 40 ° C. or lower.
(6) The electrolytic aqueous solution of (5) above, in which toner or powder adhesive is dispersed, is dropped onto the round bottom beaker of (1) above installed in the sample stand, and the measured concentration becomes 5%. To prepare. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle size is calculated.

(Operation during image formation)
Next, the image forming operation performed by the image forming apparatus 1 of this embodiment will be described with reference to FIGS. 1 to 8. 3 and 4 are diagrams showing a sheet transport path in the image forming apparatus 1. 5 (a to f) are diagrams for explaining the contents of the folding process. 7 (a to c) are views showing a process in which the image forming apparatus 1 creates a paper bag which is a bag-shaped adhesive printed matter from one sheet P. FIG. 7 (a) shows an image formed on the first surface of the sheet P with the printing toner, and FIG. 7 (b) shows a pattern of applying the powder adhesive to the second surface of the sheet P, FIG. 7 (c). Represents a paper bag that is output as a deliverable after the bonding process.

When the image data to be printed and the print execution command are input to the image forming apparatus 1, the control unit of the image forming apparatus 1 conveys the sheet P to form an image, and if necessary, a post-processing unit. A series of operations (image forming operation) for performing post-processing according to 30 is started. In the image forming operation, first, as shown in FIG. 1, the sheets P are fed one by one from the sheet cassette 8 and conveyed toward the transfer nip 5N via the transfer roller 8a.

The image forming apparatus 1 of the present embodiment conveys the sheet at a speed (process speed) of 210 mm / sec, and forms an image or applies a powder adhesive to the sheet at a printing speed of 40 single-sided printing sheets per minute. It can be carried out. When creating the paper bag shown in FIG. 7 (c), since image formation or powder adhesive is applied to the first and second surfaces of the sheet P, it is possible to continuously create the paper bag at a pace of about 20 copies per minute. be.

In parallel with the feeding of the sheet P, the process cartridges 7n, 7y, 7m, and 7c are sequentially driven, and the photosensitive drum 101 is rotationally driven in the clockwise direction (arrow w) in the figure at a surface speed of 210 mm / sec. At this time, the photosensitive drum 101 is uniformly charged on the surface by the charging roller 102. Further, the scanner unit 2 irradiates the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, 7c with the laser beam G modulated based on the image data to form an electrostatic latent image on the surface of the photosensitive drum 101. .. Specifically, the scanner unit 2 irradiates the photosensitive drum 101 of the process cartridges 7y, 7m, and 7c with laser light G in order to form an electrostatic latent image at a position corresponding to the image 53c shown in FIG. 7A. .. Next, the electrostatic latent image on the photosensitive drum 101 is developed as a toner image by the printing toner supported on the developing rollers 105 of the process cartridges 7y, 7m, and 7c.

The transfer belt 3a rotates at a speed of 210 mm / sec in the counterclockwise direction (arrow v) in the figure. The toner images formed in the process cartridges 7y, 7m, and 7c are primarily transferred from the photosensitive drum 101 to the transfer belt 3a by the electric field formed between the photosensitive drum 101 and the primary transfer roller 4.

Here, as shown in FIG. 1, the process cartridge 7n using the powder adhesive Tn is located most upstream among the four process cartridges in the rotation direction of the transfer belt 3a. Further, the yellow, magenta, and cyan process cartridges 7y, 7m, and 7c are arranged in this order from the process cartridge 7n toward the downstream side in the rotation direction of the transfer belt 3a. Therefore, when four types of toner images are overlapped on the transfer belt 3a, the powder adhesive Tn becomes the lowest layer (the layer in contact with the transfer belt 3a), and yellow (Ty), magenta (Tm), and cyan (Tc) are placed on the lowermost layer. ) The printing toners are stacked in order.

The toner image supported on the transfer belt 3a and reached the transfer nip 5N is conveyed along the main transfer path 1 m by the electric field formed between the secondary transfer roller 5 and the secondary transfer inner roller 3b. Secondary transcription to. At that time, the top and bottom of the toner layer are reversed. That is, on the sheet P that has passed through the transfer nip 5n, cyan (Tc), magenta (Tm), and yellow (Ty) printing toners are overlapped from the lowest layer (the layer that contacts the sheet P), and powder is further placed on the sheet P. A layer of adhesive Tn is formed. Therefore, in the toner image transferred to the sheet P, the layer of the powder adhesive Tn becomes the outermost surface.

After that, the sheet P carrying the unfixed toner image is conveyed by sandwiching the fixing nip 6N together with the fixing film 6a while keeping the image surface side of the sheet P in close contact with the outer surface of the fixing film 6a in the fixing nip 6N. The speed of the first fixing device 6 is adjusted so that the surface speed of the pressure roller 6b is 210 mm / sec, and the sheet P is sandwiched and conveyed in synchronization with the transfer process. In this sandwiching and transporting process, the heat of the heater 6a1 is applied to the image surface of the sheet P via the fixing film 6a, and the printing toners Ty, Tm, Tc and the powder adhesive Tn are melted and fixed on the sheet P. .. The sheet P that has passed through the fixing nip 6N is subjected to curvature separation from the fixing film 6a while retaining the fixed toner image, and an image fixed on the sheet P is obtained.

The sheet P is sandwiched and conveyed by the first discharge roller 34a and the intermediate roller 34b by the switching guide 33 rotated in the clockwise direction. After the rear end of the sheet P in the traveling direction passes through the switching guide 33, the switching guide 33 rotates counterclockwise, the intermediate roller 34b reverses, and the sheet P is reversely conveyed to the double-sided transfer path 1r. Then, while the sheet P passes through the main transport path 1 m again with the front and back reversed, the powder adhesive Tn is applied to the second surface of the sheet P in the coating pattern shown in FIG. 7 (b). The process of applying the powder adhesive Tn to the second surface of the sheet P is the process of forming the image 53c on the first surface, except that the powder adhesive Tn is used instead of the printing toners Ty, Tm, and Tc as the developing agent. Is similar to.

It is preferable that the powder adhesive Tn is applied to the second surface rather than the first surface in the double-sided printing operation. This is because if the powder adhesive Tn is applied to the first surface, the powder adhesive Tn is heated in the fixing step of the first surface and then comes into contact with the pressure roller 6b on the opposite side of the fixing film 6a in the fixing step of the second surface. This is because the temperature drops. On the other hand, the powder adhesive Tn applied to the second surface receives heat from the fixing film 6a in the fixing process of the second surface, and can enter the folding process while the temperature is relatively high.

The sheet P discharged from the apparatus main body 10 regardless of single-sided printing or double-sided printing is sandwiched between the intermediate roller 34b and the second discharge roller 34c as shown in FIGS. 3 and 4, and is first held by the tray switching guide 13a. It is transported to the route R1 or the second route R2.

The first path R1 shown in FIG. 3 is a path in which the sheet P that has passed through the first fixing device 6 is discharged to the first discharge tray 13 by the discharge unit 34 in the normal printing mode in which the post-processing unit 30 is not used. .. In the second path R2 shown in FIG. 4, in the adhesive printing mode, the sheet P that has passed through the first fixing device 6 is discharged to the second discharging tray 35 via the discharging unit 34, the folding device 31, and the second fixing device 32. It is a route to be done.

An intermediate path 15 is provided between the first fixing device 6 and the folding device 31 in the second path R2. The intermediate path 15 is a sheet transport path passing through the upper surface portion (top surface portion) of the image forming apparatus 1, and extends substantially parallel to the first discharge tray 13 on the lower side of the first discharge tray 13. No opening is provided in the area from the tray switching guide 13a to the folding device 31 in the sheet transport direction, so that the heat of the sheet P is not discharged into the air as much as possible. The intermediate pass 15 and the first discharge tray 13 are inclined upward in the vertical direction toward the folding machine 31 in the horizontal direction. Therefore, the inlet of the folding device 31 (the following guide roller pair (31c, 31d)) is located vertically above the outlet of the apparatus main body 10 (the nip of the intermediate roller 34b and the second discharge roller 34c).

The folding device 31 has four rollers, a first guide roller 31c, a second guide roller 31d, a first folding roller 31a, and a second folding roller 31b, and a pull-in portion 31e. The first guide roller 31c and the second guide roller 31d are a pair of guide rollers that sandwich and transport the sheet P received from the transport path (intermediate path 15 in this embodiment) on the upstream side of the folding device 31. The first folding roller 31a and the second folding roller 31b are a pair of folding rollers that feed out while bending the sheet P. With this configuration, the sheet P is delivered from the discharge unit 34 to the guide roller pair without delay.

Since the second guide roller 31d, which is a rotating body in contact with the sheet, comes into contact with the powder adhesive Tn on the sheet P, the surface is covered with a material having a low thermal conductivity so as not to take away the heat of the powder adhesive Tn as much as possible. Moreover, it is desirable to reduce the contact area by giving an appropriate unevenness to the surface. An EPDM rubber layer was formed on the surface of the second guide roller 31d, and the surface roughness (10-point average roughness Rzjis) was set to 10 μm or more. A surface roughness of 10 μm or more is preferable in order to minimize contact with paper while obtaining a sufficient frictional force. The surface roughness (Rzjis) shown here is a value measured using a surface roughness measuring instrument SE-3400 (trade name) manufactured by Kosaka Research Institute Co., Ltd.

Further, the second guide roller 31d has a hollow structure (a structure in which a space is provided inside the outer peripheral portion in contact with the sheet in the radial direction), so that the heat capacity can be reduced so that the temperature rises quickly with a small amount of heat. desirable. In this embodiment, the core metal of the second guide roller 31d is a pipe-shaped hollow roller having a thickness of 1 mm.

Regarding the three rollers of the first guide roller 31c, the first folding roller 31a, and the second folding roller 31b, which are other examples of the rotating body in contact with the seat, the second guide roller is also used so as not to take away the heat of the seat as much as possible. It has the same configuration as 31d.

The distance M (FIG. 1) from the second discharge roller 34c to the first guide roller 31c in the sheet transport direction along the second path R2 is the total length L (FIG. 5) of the sheet P before the folding process in the transport direction. It is configured to be shorter than (a)). This eliminates the need to provide an additional transfer roller between the second discharge roller 34c and the folding device 31, and prevents the heat of the sheet from being taken away by such a transfer roller.

The folding process by the folding device 31 will be described with reference to FIGS. 5 (a to 5). When the folding process is executed, the first guide roller 31c and the first folding roller 31a rotate in the clockwise direction in the drawing, and the second guide roller 31d and the second folding roller 31b rotate in the counterclockwise direction in the drawing. The rotation speed is 210 mm / sec at the surface speed of each roller when the sheet P is introduced. First, the tip q of the sheet P sent out from the discharge unit 34 is drawn into the guide roller pair (31c, 31d) as shown in FIG. 5A. At this time, since the powder adhesive Tn is applied to the lower surface of the sheet P in the drawing, the powder adhesive Tn comes into contact only with the guide roller 31d. As shown in FIG. 5B, the tip q of the sheet P is guided downward by the guide wall 31f and comes into contact with the first folding roller 31a, and the first folding roller 31a and the second guide roller facing each other are facing each other. It is pulled into 31d and comes into contact with the wall 31g of the pull-in portion 31e.

As the sheet P is pulled in by the guide roller pair (31c, 31d), the tip q advances to the back of the pulling portion 31e while sliding in contact with the wall 31g. Eventually, the tip q abuts on the end 31h of the retractable portion 31e as shown in FIG. 5 (c). The retracting portion 31e forms a space extending substantially parallel to the intermediate path 15 on the lower side of the intermediate path 15, and the sheet P is wound around the second guide roller 31d at the stage of FIG. 5C. It will be bent in a U shape.

When the sheet P is further pulled in by the guide roller pair (31c, 31d) from the state of FIG. 5 (c), deflection begins to occur in the middle abdomen r as shown in FIG. 5 (d). Eventually, as shown in FIG. 5 (e), when the middle abdomen r comes into contact with the second folding roller 31b, it is drawn into the nip portion of the folding roller pair (31a, 31b) by the frictional force received from the second folding roller 31b. Then, as shown in FIG. 5 (f), the sheet P is discharged with the middle abdomen r at the head by the folding roller pair (31a, 31b) in a state of being folded with the middle abdomen r as a crease.

Here, the depth N of the pull-in portion 31e (FIG. 5 (e)), that is, the distance from the nip portion of the folding roller pair (31a, 31b) to the end portion 31h of the pull-in portion 31e is half the total length L of the sheet P. It is set to the length of. As a result, the folding device 31 can execute a process (middle folding) of folding the sheet P in half with a half length. By changing the depth N of the retracting portion 31e, the position of the crease can be arbitrarily changed.

When the sheet P is discharged, the transfer speed (surface speed) of the folding roller pair is decelerated according to the transfer speed of the second fuser 32 just before the sheet P reaches the adhesive nip 32N of the second fuser 32. .. That is, the folding device 31 changes the sheet transfer speed from the sheet transfer speed V1 of the first fuser 6 to the sheet transfer of the second fuser 32 before the tip of the sheet P in the sheet transfer direction reaches the second fuser 32. Decelerate to speed V2. Specifically, since the sheet transfer speed V2 of the second fixing device 32 is 105 mm / sec, the sheet transfer speed of the folding roller pair is reduced from 210 mm / sec to 105 mm / sec. It is desirable that the timing of deceleration is as late as possible, which makes it possible to shorten the time difference from the end of the fixing process to the start of the bonding process. As this time difference is shorter, the heat stored in the sheet P in the fixing step is not dissipated as much as possible, and the bonding step can be started while the temperature of the powder adhesive Tn is high.

The folding device 31 described above is an example of folding means, and for example, a folding mechanism that forms a crease by pressing a blade against the sheet P and pushing it into the nip portion of the roller pair may be used. Further, the content of the folding process is not limited to bi-folding, and for example, a folding mechanism for executing Z-folding or tri-folding may be used. Since the folding device 31 of the present embodiment is composed of a rotating roller and a fixed pull-in portion 31e, the drive mechanism can be simplified as compared with the folding mechanism using a blade that reciprocates. Further, since the folding machine 31 of the present embodiment may be provided with a pull-in portion 31e having a depth N of half the sheet length in addition to the four rollers, the post-processing unit 30 can be downsized. ..

The sheet P folded by the folding device 31 is conveyed to the second fixing device 32, and undergoes an adhesive process of being heated and pressurized while being sandwiched and conveyed by the adhesive nip 32N. The pressure roller 32a of the second fuser 32 is rotationally driven so that the surface speed becomes 105 mm / sec. The sheet P is bonded and conveyed by the adhesive nip 32N and is subjected to an adhesive treatment (second heat fixing to the image surface coated with the powder adhesive), so that the sheet P is adhered in a folded state as shown in FIG. To. That is, when the sheet P passes through the adhesive nip 32N, the powder adhesive Tn on the sheet P is heated and pressed in a softened state again, so that the inner surface of the sheet P is passed through the powder adhesive Tn. They are bonded (bonded) to each other.

As shown in FIG. 4, the sheet P that has undergone the adhesive treatment by the second fixing device 32 is discharged to the left side in the drawing from the discharge port 32c (second discharge port) provided in the housing 39 of the post-treatment unit 30. Will be done. Then, it is stored in the second discharge tray 35 (see FIG. 1) provided on the left side surface of the apparatus main body 10. With the above, the operation of image formation when the sheet P is conveyed through the second path R2 is completed, and the paper bag as the final product shown in FIG. 7 (c) can be obtained. The above is a description of a series of operations during image formation.

As described above, the image forming apparatus 1 of the present embodiment can output the deliverables bonded by the bonding process from the base paper such as blank paper which is not the preprinted paper. The bonding location of the folded sheet P can be changed by the application pattern of the powder adhesive Tn to the sheet P. For example, it is possible to create an envelope for enclosing a document or a semi-adhesive product such as a pay slip that is supposed to be peeled off later. Further, the image recorded by the image forming apparatus 1 using the printing toner can include a format (immutable portion) when preprinted paper is used and a variable portion such as personal information. Further, the image forming apparatus 1 of the present embodiment may be used for the purpose of using the preprinted paper as a recording medium and performing the printing process and the bonding process of the variable portion.

(Hot offset)
Next, problems that may occur when the fixing step (primary fixing step, first heating step) and the bonding step (secondary fixing step, second heating step) are performed in one image forming apparatus 1 will be described. Depending on the temperature and power conditions of the bonding process, an image defect 53d called hot offset as shown in FIG. 10A may occur. When the deliverable 54 is output, the powder adhesive Tn is applied to the inside of the folded sheet P as shown in FIG. 10 (b). In order to obtain sufficient adhesive force for the output product 54, the power supplied to the heater 32b1 of the second fixing device 32 in the bonding step (hereinafter, simply referred to as simply) so that the applied powder adhesive Tn is sufficiently softened. It is necessary to set (referred to as "power supply for the bonding process").

When the power supply in the bonding process is increased, the temperature of the heating film 32b becomes higher. However, when the temperature of the heating film 32b becomes excessively high, the image 53c of the printing toner formed on the surface of the sheet P (that is, in direct contact with the heating film 32b) is excessively melted into a liquid state. Become. It melts into a liquid and its viscosity decreases, and a part of the toner adheres to the heating film 32b from the surface of the sheet P as dirt. The attached stains reattach to the sheet P by rotating the heating film 32b once, and become apparent as the image defect 53d in FIG. 10 (a).

In order to prevent the occurrence of hot offset while ensuring the adhesive strength of the product 54, it is necessary to realize the adhesion via the powder adhesive Tn while avoiding an excessive temperature rise of the heating film 32b. In other words, it is necessary to bond the powder adhesives Tn applied to the adhesive surface of the sheet P to each other while suppressing the amount of heat supplied to the sheet P in the adhesive process.

Further, another reason why the amount of heat supplied to the sheet P in the bonding step should be suppressed is a reduction in power consumption. The first fuser 6 and the second fuser 32 are heat-fixing type heating devices (image heating devices), and execute the process with the highest power consumption in the electrophotographic process. Since the image forming apparatus 1 of this embodiment has two heating devices, one for the fixing process and the other for the bonding process, it is required to save power as much as possible. When the power supply to the device main body 10 and the post-processing unit 30 is covered by one outlet (commercial power supply plug insertion port), there may be restrictions such as the current flowing through the outlet must be kept within 15 A. be.

(Temperature change on the sheet surface after the fixing process)
FIG. 11A shows the time change of the temperature of the sheet surface from the time when the paper used as the sheet P is started to be passed through the first fixing device 6 to the time when the folded surface of the sheet P comes into contact with the paper. The horizontal axis is time and the vertical axis is the temperature measurement result. A thermocouple having a small heat capacity in the temperature detector (for example, a K-type thermocouple with a diameter of 50 μm or less manufactured by Anritsu Keiki Co., Ltd.) is attached to the surface of the sheet P, and the fixing nip 6N of the first fuser 6 is attached to the sheet P. The measurement was performed by passing it through. At that time, the potential difference signal was measured from the thermocouple with a memory high coder manufactured by Hioki Electric Co., Ltd., and the time change of the temperature was obtained.

As can be seen from the graph, the temperature continues to rise at the peak temperature while the measurement area on the sheet surface (the part of the surface facing the fixing film 6a to which the thermocouple is attached) passes through the fixing nip 6N. It has reached a certain temperature of about 110 ° C. (point X). The temperature starts to drop from the moment the measurement region exits the fixing nip 6N, and drops to about 60 ° C. when it enters the folding device 31 (point Y) as shown in FIG. 5 (a). After that, as shown in FIG. 5 (e), the temperature drops to 50 ° C. at the time (point Z) when the sheet P starts to be folded with the surface to which the thermocouple is attached inside.

In the image forming apparatus 1 of the present embodiment, the temperature at the timing of this point Z, that is, the temperature at the timing at which the adhesive surfaces coated with the powder adhesive Tn start to come into contact with each other becomes important. Specifically, the surface temperature of the surface to which the powder adhesive Tn is applied at this time is set higher than, for example, the crystallization temperature of the compatible wax added to the powder adhesive Tn (45 ° C. in this example). Therefore, sufficient bonding strength can be obtained even if the temperature of the bonding process is set low. The reason will be explained below.

The graph of FIG. 11B shows the relationship between the temperature Z [° C.] (horizontal axis) of the powder adhesive at the timing of the start of folding and the heater temperature [° C.] (vertical axis) at the time of bonding required for strong adhesion. .. For the "heater temperature at the time of adhesion required for strong adhesion", the sample sheet P is passed through the image forming apparatus 1 while gradually increasing the setting of the heater temperature of the second fixing device 32, and the product (adhesive printed matter) is repeated. It was determined by outputting and peeling off the obtained product by hand to evaluate the adhesiveness. As an evaluation standard, the level of "a state in which the adhesive surface does not peel off when an external force is applied in the direction of peeling the adhesive surface and the strength of the sheet reaches the limit first" is judged to be OK. Then, the lowest temperature among the heater temperatures of the second fuser 32 that can achieve the adhesiveness evaluated as OK is defined as "the heater temperature at the time of adhesion required for strong adhesion".

While changing the temperature Z of the powder adhesive at the timing of the start of folding, the adhesiveness of the product output through the folding step and the bonding step was repeatedly evaluated. As a result, when the sample was completely cooled to room temperature (20 ° C.) after the fixing step, sufficient adhesiveness could not be obtained unless the heater temperature of the second fixing device 32 was set to 200 ° C. Further, when the temperature Z was raised by gradually shortening the time for cooling the sample after the fixing step, the "heater temperature at the time of bonding required for strong bonding" tended to decrease.

Here, when the transport distance from the first fixing device 6 to the folding device 31 is made very short and the temperature Z of the powder adhesive at the timing of the start of folding is set to 75 ° C., the heater at the time of bonding required for strong bonding is used. The temperature was 160 ° C. Then, when the temperature Z is between 75 ° C and 20 ° C, plotting the heater temperature at the time of bonding required for strong bonding shows that the two are discontinuous at around Z = 45 [° C]. It was found that the straight lines K and L can be approximated.

If the plot points change continuously without having discontinuities, the negative correlation between the heater temperature at the time of bonding required for strong bonding and the temperature Z of the powder adhesive at the timing of the start of folding is It is thought that this can be explained simply by the magnitude relationship of the amount of heat stored. That is, the smaller the amount of heat stored in the sheet P when the sheet P reaches the adhesive nip 32N of the second fixing device 32, the more the powder adhesive Tn is heated to a temperature suitable for adhesion in the bonding step. 2 The temperature of the heater 32b1 of the fuser 32 must be raised. However, since the above-mentioned discontinuity is seen in FIG. 11B, other phenomena occur between the fixing step and the bonding step. The cause of the discontinuity in FIG. 11B can be explained as follows.

(Effect of wax component)
FIG. 12 shows the results of measuring the heat flow of the powder adhesive Tn using a differential scanning calorimetry device “Q1000” (manufactured by TA Instruments). The melting point of indium and zinc is used for temperature correction of the device detection unit, and the heat of fusion of indium is used for the correction of calorific value. Specifically, 1 mg of a sample is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference. Using the modulation measurement mode, measurement is performed in the range of 10 ° C. to 90 ° C. at a heating rate of 20 ° C./min and a temperature-decreasing rate of 20 ° C./min. The curve Qu shows the temperature rise process, and the peak Qu1 (peak due to endothermic heat at the time of melting) of the melting point of the wax appears around 70 ° C. The curve Qd shows the temperature lowering process, and the peak Qd1 of heat generation due to the crystallization of wax appears around 45 ° C.

Generally, when the toner used in the electrophotographic image forming apparatus contains a crystalline material having compatibility with the binder resin, it depends on whether or not the crystalline material is melted and compatible with the binder resin. It is known that the hardness (plasticity) of the toner changes significantly. Also in the powder adhesive Tn according to the present embodiment, the hardness (plasticity) of the powder adhesive Tn greatly changes depending on whether or not the wax contained as the crystalline material is melted. Then, it is considered that the behavior of the powder adhesive Tn in the folding step and the bonding step changes depending on whether or not the wax melted by the fixing treatment by the first fixing device 6 is crystallized by the folding step. That is, it is considered that the boundary of the discontinuity appearing in FIG. 12 is determined by the crystallization temperature of the wax, which is a crystalline material contained in the powder adhesive Tn of this embodiment, when the temperature is lowered.

The "crystallization temperature at the time of temperature decrease" of the crystalline material contained in the powder adhesive Tn can be obtained as the peak temperature (Qd1) of heat generation in the temperature decrease process from the measurement result of the heat flow as shown in FIG. 12, for example. can. When a polymer crystallizes, not only temperature but also time is important as a variable, and in general, the crystallization rate tends to decrease as the molecular weight increases. Therefore, when a polymer such as crystalline polyester is used as the crystalline material, the faster the temperature drop, the lower the crystallization start temperature may be. Therefore, the temperature lowering rate when determining the crystallization temperature at the time of lowering temperature may be set to a rate close to the average temperature lowering rate in the period from the passage of the fixing nip 6N to the arrival of the folding roller pair in the actual image forming apparatus. desirable.

Hereinafter, the behavior of the powder adhesive Tn during adhesive printing will be described. FIG. 13A shows a state in which the powder adhesive Tn is transferred onto the paper as the sheet P. FIG. 13B shows how the state of the powder adhesive Tn is changed by the first fixing device 6 in the fixing step. In the fixing nip 6N of the first fixing device 6, the heat of the heater 6a1 is applied to the powder adhesive Tn through the fixing film 6a, and the temperature of the powder adhesive Tn rises to, for example, 120 ° C., so that the powder adhesive Tn Becomes liquid. At this time, the wax as a crystalline material contained in the powder adhesive Tn is in a state of being melted and compatible with the binder resin. As a result of the powder adhesive Tn melted in a liquid state being pressed against the fixing film 6a at the fixing nip 6N, a layer of the adhesive Tn1 that wets the surface of the paper is formed so as to imitate the concaveness of the surface of the paper (even out the unevenness). Will be done.

After the sheet P has passed through the first fixing device 6, the adhesive Tn1 is solidified while filling the unevenness between the papers as shown in FIG. 13 (c), and the cellulose and the adhesive Tn1 have a sufficient contact area. By having, an intermolecular attractive force (Van der Waals force) is generated. Further, the solidified adhesive Tn1 is three-dimensionally entangled with the fibers of the paper, so that an overall mechanical bond (anchor effect) can be obtained between the adhesive and the paper. Further, since the surface of the adhesive Tn1 is leveled with the fixing film 6a while passing through the fixing nip 6N, the surface of the adhesive Tn1 after passing through the nip is the surface of the fixing film 6a (in this embodiment, the mold release of the fluororesin). The surface roughness is as smooth as that of the layer).

FIG. 14A shows a state in which the sheet P is folded so that the adhesive surfaces P1 and P2 coated with the adhesive Tn2 face each other by the folding device 31 (see FIG. 5E). The paper as the sheet P is sandwiched and pressed by the first folding roller 31a and the second folding roller 31b constituting the folding roller pair. It is considered that the discontinuity of the straight lines K and L appearing in FIG. 11B is caused by whether or not the surfaces of the adhesive Tn2 are deformed by the pressure of the folding roller pair and can be sufficiently adhered to each other. Hereinafter, the case where the adhesive Tn1 has cooled and lost its plasticity by the start of the folding step and the case where the adhesive Tn1 has maintained its plasticity will be described separately.

First, consider the case where the adhesive Tn1 has cooled and lost its plasticity by the start of the folding process. In this case, since the adhesive Tn2 has a high hardness, the adhesive Tn2 on the adhesive surfaces P1 and P2 is not easily deformed even when pressed by the folding roller pair, and the adhesive Tn2 is not easily deformed as shown in FIG. 14 (a). A gap remains between the surfaces of. When the sheet P is heated by the second fuser 32, the sheet P is supplied with heat from the heater 32b1 from the side of either the adhesive surface P1 or P2 via the heating film 32b (FIG. 10B). .. At this time, the gap shown in FIG. 14A hinders smooth heat conduction from one adhesive surface side to the other adhesive surface side. Therefore, in order to re-plasticize the adhesives Tn2 on the adhesive surfaces P1 and P2 on both sides to obtain sufficient adhesiveness, it is necessary to supply a large amount of heat in a short time in the adhesive process.

On the other hand, when the hardness of the adhesive Tn2 is low at the time of starting folding by the folding roller pair, the adhesive Tn2 on the adhesive surfaces P1 and P2 is deformed relatively easily by being pressed by the folding roller pair. As shown in 14 (b), the surfaces of the adhesive Tn3 are in close contact with each other. In this case, the heat supplied from the heater 32b1 via the heating film 32b is smoothly transferred from one adhesive surface side to the other adhesive surface side. As a result, as compared with the state shown in FIG. 14 (b), at least sufficient adhesiveness can be obtained with the amount of heat supplied in the bonding step.

In the straight line K on the lower temperature side than the discontinuity in FIG. 11B, the adhesive cooled and the wax crystallized by the time the sheet P reached the folding device 31, and the wax crystallized at the time of the start of folding by the folding device 31. It is probable that the hardness of the adhesive was high. As a result, even after being folded by the folding roller pair, a gap remains between the adhesives, and the heater temperature at the time of bonding required for strong adhesion increases.

On the other hand, in the straight line L on the high temperature side of the discontinuity in FIG. 11B, the temperature drop until the sheet P reaches the folding device 31 is small, and the wax is basically melted and compatible with the binder resin. It is probable that the state of doing was maintained. In this state, since the plasticity of the adhesive is maintained by the plasticizing action of the wax, the adhesives adhere to each other relatively easily when folded by the folding roller pair. As a result, it is considered that the heater temperature at the time of bonding required for strong bonding is lower than the temperature on the straight line extrapolated by the straight line K. As described above, regarding the temperature Z of the powder adhesive at the timing of the start of folding, the heater temperature at the time of adhesion required for strong adhesion (straight line of FIG. 11 (b)) is defined at around 45 ° C., which is the crystallization temperature of the wax. Explain the mechanism by which K and L) are discontinuous.

As described above, by folding the wax as a crystalline material before crystallizing and bringing the surfaces of the adhesive into close contact with each other, the heater temperature in the bonding process is kept as low as possible while maintaining sufficient adhesive strength. Obtainable. By keeping the heater temperature low, it is possible to reduce the possibility of hot offset of the image formed by the printing toner. In addition, the power consumption of the bonding process can be reduced.

In order to realize this, it is effective to shorten the elapsed time from the fixing process to the folding process. This makes it possible to perform the folding process while a larger portion of the heat stored in the sheet remains in the fixing process. Further, it is effective to reduce the amount of heat taken from the sheet by the member (particularly, the folding roller pair) that comes into contact with the sheet between the fixing process and the folding process. Specifically, in this embodiment, the following configurations are combined.
(A) By appropriately roughening the surface roughness of the folding roller pair to reduce the contact area with the sheet, the amount of heat taken from the sheet by the folding roller pair is reduced.
(B) By making the folding roller pair a hollow structure to reduce the heat capacity, the amount of heat taken from the sheet by the folding roller pair is reduced.
(C) By setting the opening ratio of the top surface portion (region 39a in FIG. 6) of the cover member covering the upper surface of the post-processing unit 30 on which the folding device 31 is mounted to 5% or less, the area around the folding roller pair is warm. It retains air and reduces the amount of heat that the folding roller pair takes from the seat.
(D) The sheet transport speed is maintained as much as possible from the time when the sheet passes through the first fuser 6 until just before the tip of the sheet reaches the adhesive nip 32N of the second fuser 32, and the tip of the sheet is the adhesive nip. Immediately before reaching 32N, the sheet transfer speed is reduced. As a result, the elapsed time from the fixing step to the folding step can be shortened, and the heat stored in the sheet in the fixing step can be utilized.

In addition, in order to perform the folding step in a state where the plasticity of the powder adhesive Tn is maintained, the above (a) to (d) may be used alone or in combination of two or more. That is, the sheet in the section from the fixing step to the folding step depends on the properties of the crystalline material that imparts plasticity to the powder adhesive (particularly, the crystallization temperature at the time of lowering the temperature), the temperature setting of the first fixing device 6, and the like. It is only necessary to consider how much the cooling should be suppressed.

In Example 1, as a method of performing the folding process in a state where the plasticity of the powder adhesive is maintained, the molten state of the wax as a crystalline material is maintained by retaining the heat supplied to the sheet in the fixing process as much as possible. Explained to maintain. In this example, a method for preparing a crystalline material is examined so that the plasticity of the crystalline material is maintained even at a lower temperature. Hereinafter, it is assumed that the elements having the same reference numerals as those of the first embodiment have substantially the same configuration and operation as those of the first embodiment, and the parts different from those of the first embodiment will be described.

An example of manufacturing the powder adhesive according to this embodiment will be described. Similar to the powder adhesive Tn of Example 1, this powder adhesive is contained in the powder storage portion 104n of the image forming apparatus 1 and is applied to the sheet by an electrophotographic process when producing an adhesive printed matter. be.

(Production example of crystalline polyester dispersion)
In a beaker with a stirrer, 100.0 parts ethyl acetate, 30.0 parts crystalline polyester (condensation of 1,10-decanediol and sebacic acid, number average molecular weight (Mn) 7200, melting point 72 ° C), 0.3 part of 0.1 mol / L sodium hydroxide, and 0.2 part of anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and heated to 60.0 ° C. Then, stirring was continued until it was completely dissolved. While further stirring, 90.0 parts of ion-exchanged water was gradually added, emulsified in phase, and the solvent was removed to obtain a crystalline polyester dispersion (solid content concentration: 20% by mass).

(Production example of amorphous polyester)
First, the following materials were prepared.
・ Telephthalic acid 30.0 parts ・ Isophthalic acid 10.0 parts ・ Sebasic acid 15.0 parts ・ Dodecenyl succinic acid 20.0 parts ・ Trimellitic acid 6.9 parts ・ Bisphenol A ethylene oxide (2 mol) adduct 70.0 Part ・ Bisphenol A propylene oxide (2 mol) adduct 90.0 part ・ Dibutyltin oxide 0.1 part

The above material was placed in a heat-dried two-necked flask, and nitrogen gas was introduced into the container to maintain an inert atmosphere and the temperature was raised while stirring. Then, the polycondensation reaction was carried out at 150 to 230 ° C. for about 13 hours, and then the pressure was gradually reduced at 210 to 250 ° C. to obtain an amorphous polyester. The obtained amorphous polyester had a number average molecular weight (Mn) of 19,400, a weight average molecular weight (Mw) of 85,000, and a glass transition temperature (Tg) of 58 ° C.

(Production example of amorphous resin dispersion)
An amorphous resin particle dispersion was obtained in the same manner as in the production example of the crystalline polyester dispersion except that the above crystalline polyester was changed to the amorphous polyester.

(Production example of wax dispersion)
The following materials were prepared.
・ Behenic behenate (melting point 72 ° C) 50.0 parts ・ Anionic surfactant 0.3 parts (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK)
・ 150.0 parts of ion-exchanged water

The above was mixed, heated to 95 ° C., and dispersed using a homogenizer (Ultratalax T50 manufactured by IKA). Then, it was dispersed with a manton-goulin high-pressure homogenizer (manufactured by Gorin) to prepare a wax dispersion (solid content concentration: 20% by mass) in which wax particles were dispersed.

(Manufacturing example of powder adhesive)
The following materials were prepared.
・ Amorphous resin dispersion (solid content 20% by mass) 150.0 parts ・ Crystalline polyester dispersion (solid content 20% by mass) 65.0 parts ・ Wax dispersion (solid content 20% by mass) 20.0 parts

The above materials were put into a beaker, adjusted so that the total number of copies of water was 250, and then the temperature was adjusted to 30.0 ° C. Then, the mixture was mixed by stirring at 5000 rpm for 1 minute using a homogenizer (Ultratarax T50 manufactured by IKA).

Further, as a flocculant, 10.0 parts of a 2.0 mass% aqueous solution of aluminum chloride, which is a polyvalent metal compound, was gradually added. The raw material dispersion was transferred to a polymerization kettle equipped with a stirrer and a thermometer, heated to 50.0 ° C. with a mantle heater, and stirred to promote the growth of aggregated particles.

After 60 minutes had passed, 200.0 parts of a 5.0 mass% aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare an aggregated particle dispersion. Subsequently, the aggregated particle dispersion was adjusted to pH 8.0 using a 0.1 mol / L sodium hydroxide aqueous solution, and then the aggregated particle dispersion was heated to 80.0 ° C. and left for 180 minutes to allow the aggregated particles. We went to unite.

After 180 minutes, a powder adhesive particle dispersion liquid in which the powder adhesive particles were dispersed was obtained. After cooling to 40 ° C. or lower at a temperature lowering rate of 300 ° C./min, the powder adhesive particle dispersion was filtered and washed with ion-exchanged water, and the powder adhesive particles were taken out. The obtained powder adhesive particles were dried in an oven at 40 ° C. for 24 hours to obtain powder adhesive particles.

0.5 parts of sol-gel silica having a particle diameter of 100 nm and silica fine particles having an average particle size of 12 nm are treated with silicone oil on 100 parts of powder adhesive particles, and the BET specific surface area value after the treatment is 120 m2 / 0.8 parts of hydrophobic silica fine particles of g were added. Then, FM mixer (manufactured by Nippon Coke Industries Co., Ltd.) was used for mixing to obtain a powder adhesive. The glass transition temperature of the obtained powder adhesive was 49 ° C., and the weight average particle size was 5.8 μm.

In the powder adhesive obtained by the above method, the crystalline polyester acts as a plasticizer that imparts plasticity to the powder adhesive when heated. In other words, the crystalline polyester functions as the crystalline material of this example. That is, when the powder adhesive, which is an aggregate of the crystalline polyester and the amorphous resin, is heated, the crystalline polyester melts and is compatible with the amorphous resin, so that the powder adhesive can be easily deformed. Has the effect of making it.

Then, in the case of the powder adhesive of this example, crystallization of crystalline polyester occurs even if the temperature of the adhesive is lowered to a temperature lower than the crystallization temperature (about 45 ° C.) of the wax of Example 1 after the fixing treatment. do not have. That is, when the graph of FIG. 12 is drawn, the temperature at which the straight lines K and L are discontinuous becomes a lower value (for example, 5 ° C. or less). In this case, when the powder adhesive of this example is used, the plasticity of the adhesive is maintained even if the surface temperature of the adhesive drops to, for example, room temperature after the fixing treatment. Therefore, the surfaces of the adhesive can be relatively easily adhered to each other in the folding step, and sufficient adhesive strength can be obtained while reducing the amount of heat supplied to the sheet in the bonding step.

Further, in this embodiment, it is sufficient to reduce the amount of heat supplied to the sheet in the bonding process without providing the configuration ((a) to (d) above) for retaining the heat supplied to the sheet in the fixing process. Since it is possible to obtain a high degree of adhesive strength, there is an advantage that the degree of design freedom is increased. However, it is also possible to use both a method of lowering the crystallization temperature of the crystalline material contained in the powder adhesive when the temperature is lowered and a method of retaining the heat supplied to the sheet in the fixing step.

(Other embodiments)
In Examples 1 and 2, a film-type image heating device having excellent quick startability is adopted as the first fixing device 6 and the second fixing device 32, but the configuration of the image heating device is not limited to this. For example, an image heating device of a type that heats the toner and the powder adhesive on the sheet P via a heating roller that is in pressure contact with the pressure rollers 6b and 32a may be used as the first fixing device 6 and / or the second fixing device 32. good. The heating roller has, for example, an elastic layer such as silicone rubber and a release layer such as fluororesin formed on the outer peripheral portion of a metal cylinder. Further, the nip forming unit in the film method is not limited to the one in which the heater directly contacts the inner surface of the film, but the heater is configured to contact the film via a sheet material having high thermal conductivity such as iron alloy or aluminum. May be good. Further, the heating means is not limited to the one using a heat generation resistor, and may be, for example, a halogen lamp or an induction heating mechanism.

1 ... Image forming apparatus / 1e ... Image forming means (image forming unit) / 6 ... Fixing means (first fixing device) / 31 ... Folding means (folding device) / 31a, 31b ... Rotating body, roller member (first folding) Roller, 2nd folding roller) / 32 ... Adhesive means (2nd fixing device) / Tn ... Powder adhesive / Ty, Tm, Tc ... Printing toner

Claims (13)

An image forming means for forming a toner image on a sheet using printing toner and applying a powder adhesive to the sheet.
A fixing means for heating and fixing the toner image formed on the sheet by the image forming means to the sheet.
A folding means for folding the sheet that has passed through the fixing means, and a folding means.
An adhesive means for heating a sheet folded by the folding means and adhering the sheet with the powder adhesive,
It is an image forming apparatus equipped with
The folding means has a rotating body that rotates in contact with the sheet.
The ten-point average roughness Rzjis of the surface of the rotating body is 10 μm or more.
An image forming apparatus characterized in that. The rotating body has a hollow structure.
The image forming apparatus according to claim 1. An image forming means for forming a toner image on a sheet using printing toner and applying a powder adhesive to the sheet.
A fixing means for heating and fixing the toner image formed on the sheet by the image forming means to the sheet.
A folding means for folding the sheet that has passed through the fixing means, and a folding means.
An adhesive means for heating a sheet folded by the folding means and adhering the sheet with the powder adhesive,
It is an image forming apparatus equipped with
The folding means has a rotating body that rotates in contact with the sheet.
The rotating body has a hollow structure.
An image forming apparatus characterized in that. The rotating body is a roller member that sandwiches and rotates the sheet and conveys the sheet while folding it so that the surface to which the powder adhesive is applied is on the inside.
The image forming apparatus according to any one of claims 1 to 3. A cover portion provided above the folding means and the bonding means and covering the folding means and the bonding means when viewed in the direction of gravity is further provided.
The cover portion is provided with an opening for communicating the space above the image forming apparatus and the internal space of the image forming apparatus.
The ratio of the opening area of the opening to the area of the cover as seen in the direction of gravity is 5% or less.
The image forming apparatus according to any one of claims 1 to 4. An image forming means for forming a toner image on a sheet using printing toner and applying a powder adhesive to the sheet.
A fixing means for heating and fixing the toner image formed on the sheet by the image forming means to the sheet.
A folding means for folding the sheet that has passed through the fixing means, and a folding means.
An adhesive means for heating a sheet folded by the folding means and adhering the sheet with the powder adhesive,
A cover portion provided above the folding means and the adhesive means and covering the folding means and the adhesive means when viewed in the direction of gravity.
It is an image forming apparatus equipped with
The cover portion is provided with an opening for communicating the space above the image forming apparatus and the internal space of the image forming apparatus.
The ratio of the opening area of the opening to the area of the cover as seen in the direction of gravity is 5% or less.
An image forming apparatus characterized in that. The sheet transport speed of the adhesive means is slower than the sheet transport speed of the fixing means.
The folding means said that after starting to convey a sheet toward the adhesive means at a sheet transfer speed faster than the sheet transfer speed of the adhesive means, and before the tip of the sheet in the sheet transfer direction reaches the adhesive means. Decrease the sheet transfer speed to the sheet transfer speed of the adhesive means,
The image forming apparatus according to any one of claims 1 to 6. An image forming means for forming a toner image on a sheet using printing toner and applying a powder adhesive to the sheet.
A fixing means for heating and fixing the toner image formed on the sheet by the image forming means to the sheet.
A folding means for folding the sheet that has passed through the fixing means, and a folding means.
An adhesive means for heating a sheet folded by the folding means and adhering the sheet with the powder adhesive,
It is an image forming apparatus equipped with
The sheet transport speed of the adhesive means is slower than the sheet transport speed of the fixing means.
The folding means said that after starting to convey a sheet toward the adhesive means at a sheet transfer speed faster than the sheet transfer speed of the adhesive means, and before the tip of the sheet in the sheet transfer direction reaches the adhesive means. Decrease the sheet transfer speed to the sheet transfer speed of the adhesive means,
An image forming apparatus characterized in that. The sheet transfer speed of the fixing means is V1,
Assuming that the sheet transport speed of the adhesive means is V2,
The sheet is conveyed at the speed of V1 from the time the sheet passes through the fixing means until the sheet conveying speed of the folding means is reduced.
The folding means reduces the sheet transport speed from V1 to V2 before the tip of the sheet in the sheet transport direction reaches the bonding means.
The image forming apparatus according to claim 7 or 8. The powder adhesive contains a binder resin and a crystalline material that is compatible with the binder resin and melts when heated by the fixing means.
The folding means folds the sheet in a state where the surface temperature of the powder adhesive heated by the fixing means after being applied to the sheet is higher than the crystallization temperature at the time of lowering the temperature of the crystalline material.
The image forming apparatus according to any one of claims 1 to 9. An image forming means for forming a toner image on a sheet using printing toner and applying a powder adhesive to the sheet.
A fixing means for heating and fixing the toner image formed on the sheet by the image forming means to the sheet.
A folding means for folding the sheet that has passed through the fixing means, and a folding means.
An adhesive means for heating a sheet folded by the folding means and adhering the sheet with the powder adhesive,
It is an image forming apparatus equipped with
The powder adhesive contains a binder resin and a crystalline material that is compatible with the binder resin and melts when heated by the fixing means.
The folding means folds the sheet in a state where the surface temperature of the powder adhesive heated by the fixing means after being applied to the sheet is higher than the crystallization temperature at the time of lowering the temperature of the crystalline material.
An image forming apparatus characterized in that. The crystalline material comprises an ester wax or a hydrocarbon wax.
The image forming apparatus according to claim 10 or 11. The crystalline material comprises a crystalline resin.
The image forming apparatus according to any one of claims 10 to 12, characterized in that.

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