JP2009198757A - Heat roller, fixing device, and printer - Google Patents

Abstract

A heat roller, a fixing device, and a printing device capable of improving the aesthetic appearance after printing are provided.
A heat roller of the present invention has a release layer. The surface of the release layer 14 is polished. A peeling claw 31 for peeling the recording sheet P is brought into contact with the surface of the release layer 14. The heat roller 11 melts unfixed toner and fixes it on the recording sheet P. The surface of the release layer 14 has a glossiness of 18 to 27%.
[Selection] Figure 2

Description

  The present invention relates to a heat roller, a fixing device, and a printing device.

  For example, an electrophotographic printing apparatus includes a fixing device, and the fixing device includes a heat roller. The heat roller is composed of a cylindrical metal core roller made of metal such as aluminum, an elastic layer made of silicone rubber or the like provided on the circumferential surface of the metal core roller, and a fluororesin provided on the surface layer of the elastic layer. And a halogen heater disposed in the cored bar roller.

  The release layer is formed by means such as providing a tube made of a fluororesin or the like on the elastic layer.

  In the printing apparatus, the heat roller is disposed on the printing surface side of a recording sheet such as paper, and applies a conveying force to the recording sheet. A pressure roller is disposed on the opposite side of the heat roller with the recording sheet interposed therebetween, and the pressure roller presses the recording sheet toward the heat roller. In the heat roller, a release claw for peeling the recording sheet is brought into contact with the release layer, and unfixed toner is melted and fixed on the recording sheet.

  Furthermore, in Patent Document 1, a heat roller material in which a tube is provided on an elastic layer is brought into contact with an abrasive material in which abrasive grains are applied to a film-like substrate, and is rotated. Thus, the release layer is polished.

JP 2004-205991 A

  However, according to the test results of the inventors, there are cases where streak-like rubbing traces and shine are generated on the recording sheet after printing depending on the heat roller.

  The present invention has been made in view of the above-described conventional situation, and it is an object to be solved to provide a heat roller, a fixing device, and a printing device that can improve the appearance after printing.

  The inventors have intensively studied to solve the above problems, and have found that rubbing traces and shine lines are based on peeling nails and the like. The inventors have also found that these rubbing marks and shine can be made difficult to occur depending on the glossiness of the surface of the release layer. Thus, the following present invention was completed.

The heat roller of the present invention has a release layer in which the surface is polished and a release claw for peeling the recording sheet comes into contact with the surface, and melts unfixed toner and fixes it to the recording sheet. Laura,
The surface of the release layer has a glossiness of 18 to 27%.

  According to the test results of the inventors, when the glossiness is 18% or more, streak-like gloss (decreased unevenness) hardly occurs on the printed recording sheet, and when the glossiness is 27% or less, there is a rubbing trace. Not likely to occur. On the contrary, if the glossiness is less than 18%, the printed recording sheet is liable to cause unevenness, and if the glossiness exceeds 27%, rubbing marks are generated.

  Therefore, according to the heat roller of the present invention, it is possible to improve the appearance of the recording sheet after printing.

  According to the test results of the inventors, the effect of the present invention can be exhibited if the glossiness is 18 to 27% at least at the contact portion with the peeling claw and at both sides of 10 mm.

  More preferably, the surface of the release layer has a glossiness of 23% or more. According to the test results of the inventors, when the glossiness is 23% or more, no unevenness occurs in the printed recording sheet.

  The surface of the release layer preferably has Rz of 1.25 μm or more (Claim 3). According to the confirmation of the inventors, the fact that the toner transferred to the recording sheet easily adheres to the heat roller at the same time depends on the surface roughness of the surface of the release layer. The surface roughness referred to here is not the entire uneven surface of the heat roller but the polished convex portion. The polished convex portion appears white in the micrograph. When the surface roughness of the polished convex portion is small, the toner transferred to the recording sheet easily adheres to the heat roller at the time of fixing. For this reason, the peeling claw or the like strongly slidably contacts the molten toner on the recording sheet at the contact portion, and the recording sheet is likely to be rubbed. According to the test results of the inventors, when the Rz is 1.25 μm or more, no rub marks are generated on the recording sheet after printing. This is because if Rz is 1.25 μm or more, the toner transferred to the recording sheet is difficult to adhere to the heat roller at the same time during fixing. A practical upper limit is Rz 4 μm.

  The surface of the release layer preferably has a height difference of 43 μm or less. The difference in height here is the difference in height between the convex portion and the concave portion after being polished. When the height difference is large, the heat roller is rubbed by the peeling claw or the like, and is easily worn, and only the contact portion that is in contact with the peeling claw or the like is further polished to become a smooth state. In this case, the difference in height between the contact portion and the non-contact portion becomes large, and the surface shape of the heat roller is transferred during toner fixing. As a result, the smooth surface of the abutting portion is transferred to the toner, resulting in uneven spots. According to the test results of the inventors, the height difference is 43 μm or less, and it is difficult for uneven spots to occur on the printed recording sheet.

  More preferably, the surface of the release layer has a height difference of 30 μm or less. According to the test results of the inventors, the height difference is 30 μm or less, and no unevenness occurs in the printed recording sheet. When the height difference is reduced to 10 μm, the glossiness becomes 35% or more, and as a result, a rubbing trace is generated. Therefore, the lower limit is preferably 10 μm.

  The fixing device according to the present invention includes the heat roller (claim 6). If this fixing device is employed in a printing apparatus, the aesthetic appearance after printing by the printing apparatus can be improved.

  The printing apparatus of the present invention includes the fixing device (claim 7). According to this printing apparatus, the aesthetics after printing can be improved.

  A first embodiment in which the present invention is embodied in an electrophotographic printing apparatus, a so-called laser printer, will be described below with reference to the drawings.

1. Configuration and Operation of Laser Printer As shown in FIG. 1, this laser printer is installed with the upper side of the paper as the upper side in the direction of gravity, and is normally used with the right side of the paper as the front side.

  The laser printer includes a substantially rectangular parallelepiped casing 1, a sheet feeding unit 2 installed in the casing 1, and an image forming unit 3 that forms an image on a sheet conveyed by the sheet feeding unit 2. Yes. The image forming unit 3 includes a scanner unit 4, a plurality of developing cartridges 5, and a fixing device 6. The image forming unit 3 according to the first embodiment is a so-called direct tandem type capable of color printing.

  The fixing device 6 is disposed on the downstream side of the photosensitive drum of the developing cartridge 5 on the most downstream side in the sheet conveyance direction, and is detachably assembled from the housing 1. The fixing device 6 includes a heat roller 11 and a pressure roller 21 in a case 10.

  As shown in FIGS. 2 and 3, the heat roller 11 includes a cylindrical cored bar roller 12 made of aluminum, an elastic layer 13 provided on the circumferential surface of the cored bar roller 12, and a surface layer of the elastic layer 13. It has a release layer 14 provided and a halogen heater 15 disposed in a cored bar roller.

  The elastic layer 13 is formed by means such as applying silicone rubber or the like to the circumferential surface of the cored bar roller 12. The release layer 14 is formed by means such as providing a tube on the elastic layer 13. The heat roller material provided with the tube is polished by automatic polishing. The abrasive is obtained by applying abrasive grains such as alumina and silicon carbide to a film-like substrate. The release layer 14 was polished by contacting the abrasive while rotating the heat roller material by the power of a motor or the like. Thus, the heat roller 11 was obtained. Here, the release layer 14 may be polished by contacting the abrasive while manually rotating the heat roller material.

  In the laser printer, the heat roller 11 is disposed on the printing surface side of the recording sheet P. A pressure roller 21 is disposed on the opposite side of the heat roller 11 with the recording sheet P interposed therebetween.

  The pressure roller 21 includes a rotating shaft 22 made of a metal such as aluminum, and an elastic layer 23 that is elastically deformable such as silicone rubber provided on a circumferential surface of the rotating shaft 22.

  As shown in FIG. 3, the case 10 of the fixing device 6 is provided with a peeling claw 31 for peeling the recording sheet P and a thermistor 32 for detecting the temperature of the heat roller 11. The release claw 31 and the thermistor 32 are in contact with the release layer 14.

  The heat roller 11 is energized to the halogen heater 15 while being driven. Thereby, a conveyance force is applied to the recording sheet P. At this time, the pressure roller 21 presses the recording sheet P toward the heat roller 11. The heat roller 11 melts unfixed toner and fixes it on the recording sheet P.

2. Test Various tests were performed on the heat roller 11 of the laser printer, and a test was performed to determine whether streaky rubbing marks and shine were generated on the printed paper. Each of the heat rollers 11 has different grain sizes of abrasive grains in the abrasive material between # 1000 and # 6000.

2.1 Glossiness Glossiness was measured as follows. The measuring device is “Gloss Meter VG2000” manufactured by Nippon Denshoku Industries Co., Ltd. As shown in FIG. 4, a plate-like measurement attachment 41 having a slit 41a formed at the center is prepared, and this measurement attachment 41 is placed on the measurement window of the measuring device, and the axis of each heat roller 11 is arranged in the longitudinal direction of the slit 41a. The directions were matched. In this state, each heat roller 11 was fixed, and as shown in FIG. 5, the light L was irradiated from the measuring device within the plane including the axis of each heat roller 11. The angle that the light L makes with the axis of each heat roller 11 is 75 °. The measuring device measures the glossiness (%), which is the ratio of the incident light quantity as the denominator and the reflected light quantity as the numerator.

2.2 Surface Roughness The heat roller material provided with the tube has irregularities as shown in FIG. 6, and the convex portion 141 appears white and the concave portion 142 appears black in the micrograph. As shown in FIG. 7, the heat roller 11 obtained by polishing the heat roller material also has irregularities, and in the micrograph, the convex portion 143 appears white and the concave portion 144 appears black. In the heat roller 11 after polishing, the ratio of the convex portions 143 is larger than that in the heat roller material before polishing. The surface roughness Rz (μm) is not for the entire uneven surface of each heat roller 11 but for the polished convex portion 143.

2.3 Height Difference The height difference (μm) is the difference in height between the polished convex portion 143 and the concave portion 144.

2.4 Other conditions The pressure of the heat roller 11 and the pressure roller 21 is about 0.01358 kgf / mm ² , the heating temperature of the heat roller 11 is 160 to 220 ° C., and the pressure of the peeling claw 31 is Is 3 to 15 kgf / mm ² . The elastic layer 13 of the heat roller 11 is made of silicone rubber having a thickness of 0.2 to 1.0 mm. The release layer 14 has a thickness of 30 to 50 μm. The print image is obtained by painting the recording sheet P. The surface resistivity of the release layer 14 is 10 ⁷ Ω or more and 10 ¹⁴ Ω or less. The toner is a non-magnetic type having a melt flow rate at 125 ° C. of 1 kg / min or more and 10 kg / min or less, and has a multilayer structure (specifically, a two-layer structure). belongs to. Incidentally, this toner is composed of a material whose outer surface layer is harder than the inner surface.

2.5 Results Table 1 shows the results of whether or not streak-like rubbing traces (claw marks) were generated when various heat rollers 11 having different glossiness and Rz were used. The result 1 is that the heating temperature of the heat roller 11 is 220 ° C, and the result 2 is that the heating temperature of the heat roller 11 is 195 ° C. The numerical value given in the results 1 and 2 is the length of the rubbing trace. ○ indicates that no streak-like rubbing trace was generated, Δ indicates that a streak-shaped rubbing trace was generated shortly, and x indicates that a streak-shaped rubbing trace was generated long.

  In addition, Table 2 shows the results of whether or not streaky shine (shine unevenness) occurred when various heat rollers 11 having different glossiness and height difference were used. ○ indicates that even if the viewing angle of the printed recording sheet P is changed, the unevenness cannot be seen. Δ indicates that the viewing angle is viewed obliquely when the viewing angle of the printed recording sheet P is oblique. The angle at which the subsequent recording sheet P is viewed Indicates that the unevenness is noticeable without changing the viewing angle.

From Table 2, it can be seen that if the glossiness is 18% or more, the unevenness in the recording sheet P after printing is hardly generated, and if the glossiness is 23% or more, the unevenness in the recording sheet P after printing does not occur. . On the contrary, if the glossiness is less than 18%, the printed recording sheet P will be uneven. Further, it can be seen from Table 1 that if the glossiness is 27% or less, no rubbing trace is generated at a heating temperature of 220 ° C., and no rubbing trace is generated at a heating temperature of 195 ° C. On the contrary, if the glossiness exceeds 27%, rubbing traces are generated. When the glossiness exceeds 27%, when a thin sheet of 60 g / m ² is used as a recording sheet, there is a problem that the thin paper is easily wound around the heat roller 11.

(1) If the gloss is less than 18%, the surface of the release layer 14 becomes rough. In this way, when the surface of the release layer 14 is rough, only the contact portion with which the peeling claw 31 contacts is easily worn out of the surface of the release layer 14 and is in a further polished state. It becomes extremely smooth compared to the contact area. In this way, when only the contact portion becomes extremely smooth as compared to the non-contact portion, this smooth shape is transferred to the toner during fixing, resulting in shine unevenness.

(2) When polishing to a state where the glossiness exceeds 27%, the surface of the release layer 14 becomes smooth. Thus, when the surface of the release layer 14 is in a smooth state, the recording sheet P is likely to be attracted to the heat roller 11. As described above, when the recording sheet P is easily attracted to the heat roller 11, the peeling claw 31 and the recording sheet P are in strong contact with each other, and the recording sheet P is easily rubbed.

  Further, when Rz is 1.25 μm or more, no rubbing trace is generated at a heating temperature of 220 ° C., and rubbing trace is hardly generated at a heating temperature of 195 ° C. When Rz is 1.50 μm or more, no rubbing trace is produced at both heating temperatures. This is because the toner transferred to the recording sheet P is difficult to adhere to the heat roller 11 at the time of fixing.

  Further, when the difference in height is 43 μm or less, it is difficult to generate the unevenness, and when the difference in height is 30 μm or less, the unevenness does not occur.

  Therefore, according to the heat roller of this invention, it turns out that the beauty | look of the recording sheet after printing can be improved.

  In the above, the present invention has been described with reference to the first embodiment. However, the present invention is not limited to the first embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the spirit of the present invention. .

  The present invention is applicable to a printing apparatus.

1 is a schematic cross-sectional view of a laser printer of Example 1. FIG. It is sectional drawing of the axis-perpendicular direction of the heat roller and pressure roller of Example 1. It is sectional drawing of the axial direction of the heat roller of Example 1, and a pressure roller. FIG. 4 is a cross-sectional view in the direction perpendicular to the axis showing a method for measuring the glossiness in connection with the test of Example 1. It is sectional drawing of the axial direction which concerns on the test of Example 1 and shows the measuring method of glossiness. In connection with the test of Example 1, FIG. (A) is a schematic plan view showing an enlarged surface of a heat roller material before polishing, and FIG. (B) is a cross-sectional view taken along the line BB in FIG. In connection with the test of Example 1, FIG. (A) is a schematic plan view showing an enlarged surface of the heat roller after polishing, and FIG. (B) is a cross-sectional view taken along the line BB in FIG.

Explanation of symbols

P ... Recording sheet 31 ... Peeling claw 32 ... Temperature detection member (thermistor)
14 ... Release layer 11 ... Heat roller 6 ... Fixing device

Claims (7)

A heat roller having a release layer that has a surface that is polished and a peeling claw for peeling the recording sheet in contact with the surface, and that melts unfixed toner and fixes the recording sheet to the recording sheet,
The heat roller according to claim 1, wherein the surface of the release layer has a glossiness of 18 to 27%.   The heat roller according to claim 1, wherein the surface of the release layer has a glossiness of 23% or more.   The heat roller according to claim 1, wherein the surface of the release layer has an Rz of 1.25 μm or more.   The heat roller according to claim 1, wherein the surface of the release layer has a height difference of 43 μm or less.   The heat roller according to claim 4, wherein the surface of the release layer has a height difference of 30 μm or less.   A fixing device comprising the heat roller according to claim 1.   A printing apparatus comprising the fixing device according to claim 6.

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