JP2005331596A - Rubber latex dip apparatus for elastic roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber latex dip apparatus for elastic roller for dipping into rubber latex, when forming a rubber latex layer for an elastic roller which is represented by an electrifying roller and also suppressing outside diameter deflection. <P>SOLUTION: The rubber latex dip apparatus 30 for the elastic roller is provided with a dip tank 31, containing rubber latex solution 6 and a liquid current forming means ejecting rubber latex skim, produced on the liquid surface by only having the surface layer flow outside the dip tank 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber latex dip device used for forming a rubber latex layer of an elastic roller such as a charging roller used in an electrostatic latent image process in a copying machine, a printer, etc., in particular, a layer thickness. It is related with what can form uniformly.

  Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, first, the surface of the photosensitive member is uniformly charged, and an image is projected from the optical system to the photosensitive member to erase the charged portion. An electrostatic latent image is obtained by an electrostatic latent image process for forming a latent image, and then the electrostatic latent image is visualized as a toner image by adhesion of toner, and by transferring the toner image to a recording medium such as paper, The method of printing is taken.

  In order to charge the surface of the photosensitive member, a contact charging method for charging the surface of the photosensitive member by applying an elastic roller to the photosensitive member and applying a voltage to the elastic roller while rotating them is widely implemented. ing. The elastic roller used in this contact charging method is called a charging roller. For example, a material such as rubber or urethane foam is injected into a mold or extruded from an extruder to form an elastic layer around the shaft. The resistance adjustment layer is formed on the outside of the elastic layer in the radial direction by dip-coating a solution prepared by adding a conductive agent to a resin such as urethane, acrylic urethane, acrylic ester, nylon, or a synthetic rubber such as NBR to adjust the resistance value. It is also known that a skin layer is formed by dip coating a resin solution obtained by dissolving a resin such as acrylic, urethane, or nylon in an organic solvent or water on the outside (see, for example, Patent Document 1). .)

  In such a charging roller, by forming the elastic layer by dip coating, all layers are formed by dip coating, and attempts to reduce the investment cost of manufacturing equipment are being studied. In Japanese Patent Application No. 2004-13988, the applicant has proposed a method of manufacturing an elastic roller in which an elastic layer is formed by dipping in a rubber latex solution and solidifying.

  On the other hand, with regard to the resistance adjustment layer and skin layer formed by dip coating, if these layer thicknesses are thick, it is necessary to repeatedly apply the conventional method repeatedly, which reduces productivity. As a solution to this problem, the applicant proposed in Japanese Patent Application No. 2004-14170 a method of manufacturing an elastic roller in which at least one of these layers is formed by coagulating rubber latex.

  The outline of these proposals for coagulating rubber latex to form a layer will be described below. FIG. 1 is a cross-sectional view showing, as an example, a charging roller used to charge the surface of a photoreceptor of an elastic roller formed by the proposed manufacturing method. The charging roller 10 includes a shaft 1, an elastic layer 2 disposed around the shaft 1, a skin layer 4 that forms a roller peripheral surface, and a resistance adjustment layer provided between the elastic layer 2 and the skin layer 4. It consists of three. Here, the shaft 1 is a portion that is pivotally supported by an electrophotographic apparatus such as a printer, and is made of metal or plastic.

  One or more of the elastic layer 2, the resistance adjusting layer 3, and the skin layer 4 can be formed by coagulating rubber latex, but the elastic layer 2 is formed using a rubber latex coagulation method as an example. The process at that time will be described. FIG. 2 is a process diagram showing a flow of a process for manufacturing the charging roller 10. This manufacturing process includes a shaft supply process 21 for preparing and supplying the shaft 1, and rubber latex is dip-solidified around the shaft 1. The elastic layer forming step 22 for forming the elastic layer 2, the resistance adjusting layer forming step 24 for forming the resistance adjusting layer 3 by dipping the paint on the radially outer side of the elastic layer 2, The charging roller 10 having a skin layer forming step 26 for dipping the paint to form the skin layer 4 and a skin layer drying step 27 for forcibly drying the skin layer 4 and finishing the last skin layer drying step 27 is as follows. The process is moved to, for example, an inspection process.

  FIG. 3 is a process diagram showing the details of the process of forming the elastic layer 2 by the rubber latex coagulation method. First, in the latex undercoat process 22a, the latex dip tank containing the liquid of rubber latex emulsified in water is used. After immersing the shaft 1 serving as a base and applying a primer to the peripheral surface of the shaft 1, the undercoated shaft 1 is placed in a coagulant dip tank containing a coagulant solution in the coagulant dip coating step 22b. Immerse and coat the outside of the shaft 1 with a coagulant. Here, the undercoat latex functions as an adhesive for adhering the coagulant to the shaft 1.

  The shaft 1 coated with the coagulant is dried at room temperature by applying air, and then immersed in a rubber latex solution contained in a dip tank in a latex dip coating step 22c. At this time, the acidic coagulant and the alkali rubber latex cause an acid-alkali reaction, and the rubber latex gels and coagulates with this reaction.

  After the latex dip coating step 22c, in order to remove the water generated by the acid-alkali reaction, in the low-temperature drying step 22d, the temperature of the roller in the middle of formation is kept at, for example, about 40 ° C., followed by the acid-alkali reaction. In order to remove the salt generated in step 2, the salt is removed by washing it with water having a low salt concentration in the washing step 22e. The step of removing the salt is necessary because if the salt is not removed, the salt remains in the roller as a foreign substance and precipitates on the surface of the roller during use, causing contamination of the photoreceptor. Thereafter, the charging roller is transferred to the high temperature drying step 24f, and dried at a high temperature of, for example, about 70 to 80 degrees to evaporate water and vulcanize the latex to complete the formation of the elastic layer 2.

  FIG. 4 is a conceptual diagram showing a method of forming a rubber latex layer using a conventionally known dip device in the latex dip coating step 22c among the above steps. The dip device 80 overflows from an overflow dip tank 81 that contains the rubber latex solution 6, a circulation pump 84 that replenishes the inflow port 81 </ b> B provided in the lower part of the dip tank 81, and an upper surface 81 </ b> A of the dip tank 81. An overflow liquid receiving tank 82 for temporarily receiving the solution and a solution storage tank 83 for storing the solution from the overflow liquid receiving tank 82 are configured. The circulation pump 84 pumps up the solution from the solution storage tank 83 and circulates it. Composed.

  The dip device 80 configured in this way always keeps the liquid level from overflowing from the upper surface 81A of the dip tank 81, so that the liquid level can be kept constant, and the skim generated on the liquid level is discharged and immersed. When the substrate is pulled up, it can be prevented from adhering as a foreign substance.

In order to form a rubber latex layer using the dip device 80, one end of the shaft 1 on which the coagulant layer 7 has already been formed is gripped by the roller gripping member 8, and the shaft 1 is in a vertical posture. And then immersed in the rubber latex solution 6 accommodated in the dip tank 81, and then left in the solution 6 for a predetermined time to react the rubber latex of the solution with the coagulant to form a rubber latex layer. Can be formed.
JP 2003-131474 A

  However, when the elastic layer of the rubber latex layer is formed on the shaft 1 using the dip device 80, the thickness of the rubber latex layer is reduced by the solution flow in the dip tank 81 generated to overflow the solution. It has been found that there is a problem that the outer diameter becomes uneven in the circumferential direction and the outer diameter fluctuation exceeds the required range.

  The present invention has been made in view of such problems, and when forming a rubber latex layer of an elastic roller typified by a charging roller, it is possible to dip the rubber latex and to reduce the outer diameter fluctuation. An object of the present invention is to provide a rubber latex dip device for an elastic roller that can be suppressed.

(1) In the present invention, a coagulant layer is formed on the outer peripheral surface of a cylindrical substrate including a shaft, the substrate is dipped in a rubber latex solution, and a rubber latex layer is disposed outside the cylindrical substrate. In a rubber latex dip device used to produce an elastic roller,
A rubber latex dip device for an elastic roller comprising a dip tank for storing a rubber latex solution and a liquid flow forming means for discharging only the surface layer and discharging a rubber latex skim generated on the liquid surface to the outside of the dip tank. .

  (2) In the present invention, in (1), the liquid flow forming means is provided on the inflow weir provided on the wall surface on the upstream side of the surface layer flow and on the wall surface on the downstream side of the surface layer flow. A rubber latex dip device for an elastic roller comprising an outflow weir having a height and a surface layer flow generation tank that communicates with a dip tank via the inflow weir and holds the liquid level at a position higher than the inflow weir. .

  (3) According to the present invention, in (2), the surface flow generation tank is configured to communicate with the dip tank also through the outflow weir, and the rubber latex skim is discharged from the discharged surface flow into the surface flow generation tank. It is a rubber latex dip device for an elastic roller provided with a filter to be removed and an underwater fan that lowers the liquid level on the side adjacent to the outflow weir and raises the liquid level on the side adjacent to the inflow weir.

  (4) The present invention relates to (2), a filter for removing rubber latex skim from the discharged surface flow, a storage tank for storing the remaining solution from which rubber latex skim has been removed, and this solution from the storage tank. A rubber latex dip device for an elastic roller comprising a recirculation pump for recirculating to the surface flow generation tank.

  According to the invention of (1), it comprises a dip tank containing a rubber latex solution, and a liquid flow forming means for discharging only the surface layer and discharging the rubber latex skim generated on the liquid surface outside the dip tank. This means that the forced flow generation means for generating a liquid flow other than the surface flow is also excluded. First, by suppressing the flow inside the solution, the rubber latex layer resulting from this flow Secondly, the liquid flow forming means forms a surface flow that discharges the rubber latex skim generated on the liquid surface to the outside of the dip tank, so that the immersed substrate is removed from the solution. It is possible to prevent the rubber latex skim from adhering and becoming a foreign substance when pulled up.

  According to the invention of (2), the liquid flow forming means is provided on the inflow weir provided on the wall surface on the upstream side of the surface flow and on the wall surface on the downstream side of the surface layer flow, and has a height equal to or less than that of the inflow weir. And an outflow weir, and a surface layer generation tank that communicates with the dip tank via the inflow weir and holds the liquid level at a higher position than the inflow weir. A flow can be formed, and the flow can be kept only on the surface layer so that the liquid flow inside the solution is not affected.

  According to the invention of (3), the surface layer flow generation tank is configured to communicate with the dip tank also through the outflow weir, and the surface layer flow generation tank is configured to remove the rubber latex skim from the discharged surface layer flow. And an underwater fan that lowers the liquid level on the side adjacent to the outflow weir and raises the liquid level on the side adjacent to the inflow weir, so that the solution can be reused while removing the rubber latex skim. In addition, the surface layer flow can be generated with a simple configuration.

  According to the invention of (4), the filter for removing the rubber latex skim from the discharged surface flow, the storage tank for storing the remaining solution from which the rubber latex skim has been removed, and the surface flow from the storage tank. A recirculation pump that recirculates to the production tank is provided, so that the solution can be reused while removing the rubber latex skim, and the storage tank for storing the remaining solution is separated from the surface flow production tank. Since it is provided, it is possible to independently control the liquid level of the surface flow generation tank, and this enables fine control of the flow velocity of the surface flow.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The rubber latex dip device of the first embodiment is used in a latex dip coating process 22c in which the elastic layer 2 of the charging roller 10 shown in FIG. 1 is formed by solidifying rubber latex. FIG. 5 (a) is a cross-sectional view showing the rubber latex dipping device, and FIG. 5 (b) is a cross-sectional view corresponding to the bb cross section of FIG. 5 (a).

The rubber latex dipping device 30 is for dipping rubber latex on the shaft 1 on which the coagulant layer 7 is formed. The rubber latex dipping device 30 stores a rubber latex solution 6 and a surface flow F of the rubber latex solution 6. And a liquid flow forming means for discharging the rubber latex skim generated on the liquid surface to the outside of the dip tank. The liquid flow forming means includes an inflow weir 32 provided on the wall surface upstream of the surface layer flow, An outflow weir 33 provided on the wall surface on the downstream side and set at a height equal to or lower than the inflow weir 32, and communicated with the dip tank via the inflow weir 32, the liquid level S ₁ is higher than the inflow weir 32 And a surface flow generation tank 35 held in position.

  Here, the inflow weir 32 and the outflow weir 33 may be ones that allow the surface layer flow to flow in or out through openings formed to surround the left, right, top, and bottom, respectively. In this case, the opening forming the outflow weir 33 The lower edge of the part must be set to a height equal to or lower than the lower edge of the opening of the inflow weir 32.

  The surface layer flow generation tank 35 has a structure in which the dip tank 31 is accommodated therein, and is configured to communicate with the dip tank 31 through the outflow weir 33. The inflow weir 32 shown in FIG. The part adjacent to the outflow weir 33 and the part adjacent to the outflow weir 33 are connected through the lower part of the dip tank 31, but these parts may be connected by the side part of the dip tank 31, and further, a pipe or the like You can also communicate with.

The surface layer flow generating tank 35, a filter 36 for removing rubber latex skimmed from the discharged surface flow, the side of the liquid adjacent to the inflow gate 32 together with the lowering side of the liquid surface S ₂ which is adjacent to the outlet weir 33 provided underwater fan 37 to increase the surface S ₁ is an underwater fan 37 also has a function of forming a flow shown in figure f in the surface layer flow generation tank 35.

In such a dip system 30 constructed as above, by driving the water pump 37, with raising the liquid surface S ₁ side communicating maintained at a higher level than the inflow gate 32 to the inlet weir 32, inflow gate Since the inflow weir 32 is set at a level equal to or higher than the outflow weir 33 by holding the liquid level S2 on the side communicating with the lower level at a level lower than the inflow weir 33. From the weir 32, it can be made to flow toward the outflow weir 33, this becomes the surface layer flow F, and the rubber latex skim can be discharged. Further, since the surface layer flow F flows due to the head difference between the inflow weir 32 side and the outflow weir 33 side, it does not affect the flow of the solution interior V, so the solution interior V remains stationary. As a result, the rubber latex layer can be formed uniformly.

  In the surface flow generation tank 35, in order to maintain the respective liquid surface levels on the inflow weir 32 side and the outflow weir 33 side as described above, it is also important to maintain the total liquid amount in a state where there is no excess or deficiency. Therefore, a supply line 38 for supplying the solution and a discharge line 39 for discharging the solution are connected to the surface flow generation tank 35.

  Next, a second embodiment will be described. The rubber latex dip device of this embodiment is also used in the latex dip coating process 22c in which the elastic layer 2 of the charging roller 10 shown in FIG. 1 is formed by coagulating rubber latex. 6 is a cross-sectional view showing the rubber latex dip device of this embodiment.

The rubber latex dip device 40 has a dip tank 41 for containing the rubber latex solution 6 and a liquid flow formation for forming a surface flow F of the rubber latex solution 6 and discharging the rubber latex skim generated on the liquid surface to the outside of the dip tank. The liquid flow forming means is set to a height equal to or lower than the inflow weir 42 provided on the wall surface on the upstream side of the surface flow and the inflow weir 42 provided on the wall surface on the downstream side of the surface flow. An outflow weir 43 and a surface layer flow generation tank 45 which communicates with the dip tank via the inflow weir 42 and holds the liquid level S ₁ at a position higher than the inflow weir 42. This is the same as the embodiment.

  The dip device 40 further includes a filter 46 for removing the rubber latex skim from the discharged surface flow, a storage tank 44 for storing the remaining solution from which the rubber latex skim has been removed, and the solution from the storage tank 46. A recirculation pump 47 for recirculating to the surface flow generation tank 45 is provided.

In the dip device 40 configured as described above, only the surface layer flow F can be generated based on the same principle as the dip device 30 of the first embodiment, but by controlling the discharge amount of the circulation pump 47. The liquid level S ₁ on the side communicating with the inflow weir 42 can be controlled with higher accuracy, whereby the flow velocity of the surface layer flow F correlated with the level of the liquid level S ₁ can be set finely. As a result, the rubber latex skim is discharged and the influence on the flow of the solution inside V can be further suppressed.

  Note that a replenishment line 48 and a discharge line 49 are connected to the storage tank 44 in order to adjust the excess or deficiency of the solution in the replenishment tank 46.

An example of the preparation of the rubber latex solution contained in the rubber latex dip layer is illustrated below.
(Formulation example A)
Rubber latex (JSR0561: manufactured by JSR Corporation): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Co., Ltd.): 10 parts by mass, colloidal sulfur (colloidal sulfur: manufactured by Hosoi Chemical Co., Ltd.): 2 parts by mass Parts and a thickener (SN thickener A-815: manufactured by San Nopco Co., Ltd.): 1 part by mass are mixed with a stirring blade.

(Formulation example B)
Rubber latex (JSR0561: manufactured by JSR Corporation): 100 parts by mass, carbon black (MA100: manufactured by Mitsubishi Chemical Co., Ltd.): 10 parts by mass, colloidal sulfur (colloidal sulfur: manufactured by Hosoi Chemical Co., Ltd.): 2 parts by mass And a foaming agent (FR25: manufactured by Kao Corporation): 0.5 part by mass are mixed with a high-speed high-speed foaming stirrer to prepare a foam coating material having a foam density of 0.4 g / cm ³ .

  In any of the above (Formulation Example A) and (Formulation Example B), as a coagulation liquid in the coagulant dip coating step 24b, a coagulant (calcium nitrate tetrahydrate: manufactured by Otsuka Chemical Co., Ltd.): 50 parts by mass , And methanol: 50 parts by mass mixed with a stirring blade to adjust the coagulation liquid can be used in combination. In the above preparation examples, carbon black is used as the conductive agent, but there is no problem even if an ionic conductive agent is used instead.

  The rubber latex dipping device used for forming the rubber latex layer has been described taking the elastic layer 2 of the charging roller 10 as an example. However, the rubber latex dipping device other than the elastic layer 2 of the charging roller 10 and other rubber rollers of the elastic roller may be used. In the formation, the same rubber latex dipping device can be used, and the same effect can be obtained.

  The rubber latex dipping device 30 of the first embodiment shown in FIG. 5 is used as an example, and rubber formed by dipping the shaft with a solidified layer formed in the rubber latex solution accommodated in the rubber latex dipping device 30 A latex layer was formed, the outer diameter of the rubber latex layer was measured, and the outer diameter runout was recorded for each position in the length direction of the shaft.

  Further, the conventional overflow type dip device 80 shown in FIG. 4 is used as Comparative Example 1, and a rubber latex layer is formed under the same conditions using the dip device 80, and the underwater fan 37 is stopped. The rubber latex dip device 30 of the first embodiment held in the state of a stationary tank that does not form a surface flow was used as Comparative Example 2, and the rubber latex layer was also formed under the same conditions for the dip device 30 in this state. And also about each of the comparative example 1 and the comparative example 2, the outer diameter of the rubber latex layer was measured and the outer diameter fluctuation | variation was recorded for every position of the length direction of a shaft.

  Table 1 shows an outline of the dip conditions and the apparatus. Moreover, the measurement result of outer diameter fluctuation is shown in FIG. In FIG. 7, the vertical axis represents the magnitude of the outer diameter deflection, the horizontal axis represents the position in the shaft length direction, and the position of the upper end of the shaft is 0 mm.

  As can be seen from FIG. 7, the overflow type dip device of Comparative Example 1 had a large outer diameter fluctuation, but in the Example, the stationary tank of Comparative Example 2 at any longitudinal position. In addition, it can be seen that the outer diameter fluctuation can be suppressed.

  This rubber latex dipping device for elastic rollers is used for solidifying rubber latex to form one layer of a high-precision rubber roller composed of a plurality of layers used in an electrophotographic apparatus in addition to a charging roller. Can do.

It is sectional drawing of the charging roller used as the representative example of the elastic roller formed using the dipping apparatus of embodiment which concerns on this invention. It is process drawing which shows the flow of the process which manufactures a charging roller. It is a partial process figure at the time of forming an elastic layer by the latex coagulation method. It is a conceptual diagram which shows the method of forming a rubber latex layer using the overflow type dip apparatus conventionally known. It is sectional drawing which shows the rubber latex dipping apparatus of 1st embodiment which concerns on this invention. It is sectional drawing which shows the rubber latex dipping apparatus of 2nd embodiment. It is a graph which shows the measurement result of the outer diameter fluctuation | variation of a rubber latex layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Resistance adjustment layer 4 Skin layer 5 Rubber latex layer 6 Rubber latex solution 7 Coagulant layer 8 Roller holding member 9 Dip layer 10 Charging roller 21 Shaft supply process 22 Elastic layer formation process 22a Latex undercoat process 22b Coagulation Agent dip coating process 22c Latex dip coating process 22d Low temperature drying process 22e Cleaning process 22f Low temperature drying process 24 Resistance adjustment layer forming process 26 Skin layer forming process 27 Skin layer drying process 30 Rubber latex dip device 31 Dip tank 32 Inflow weir 33 Outflow weir 35 Surface Layer Generation Tank 36 Filter 37 Submersible Fan 38 Supply Line 39 Discharge Line 40 Rubber Latex Dip Device 41 Dip Tank 42 Inlet Weir 43 Outlet Weir 44 Storage Tank 45 Surface Layer Generation Tank 46 Filter 47 Ring Pump 48 Supply line 49 exhaust line F Surface Current

Claims (4)

In order to manufacture an elastic roller in which a coagulant layer is formed on the outer peripheral surface of a cylindrical substrate including a shaft and this substrate is dipped in a rubber latex solution, and a rubber latex layer is disposed outside the cylindrical substrate. In the rubber latex dip device used,
A rubber latex dip device for an elastic roller, comprising: a dip tank for containing a rubber latex solution; and a liquid flow forming means for discharging only the surface layer of the rubber latex skim generated on the liquid surface and discharging it to the outside of the dip tank.   The inflow weir provided on the wall surface on the upstream side of the surface layer flow, the outflow weir provided on the wall surface on the downstream side of the surface layer flow and having a height equal to or lower than the inflow weir, and the inflow weir The rubber latex dip device for an elastic roller according to claim 1, further comprising a surface layer flow generation tank that communicates with the dip tank and holds the liquid level at a position higher than the inflow weir.   A surface flow generation tank is configured to communicate with the dip tank also through the outflow weir, a filter for removing rubber latex skim from the discharged surface flow, and a side adjacent to the outflow weir. The rubber latex dip device for an elastic roller according to claim 2, further comprising an underwater fan that lowers the liquid level and raises the liquid level adjacent to the inflow weir.   A filter for removing the rubber latex skim from the discharged surface flow, a storage tank for storing the remaining solution from which the rubber latex skim has been removed, and a recirculation pump for circulating this solution from the storage tank to the surface flow generation tank. The rubber latex dip device for an elastic roller according to claim 2 comprising:

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