JP2007071968A - Method for manufacturing conductive member, and developing roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive member by which a weld line is prevented from occurring, and a developing roller. <P>SOLUTION: In the method for manufacturing the conductive member in which a conductive elastic layer 114b is formed on the outer periphery of a shaft center body 114a by using a metallic mold, and a covering layer 114c is formed on the outer periphery of the conductive elastic layer, conductive elastic layer forming material is two-liquid mixture type liquid silicone rubber. The method includes: a mixing stage for mixing two liquids by a static mixer by pouring the two liquids in the static mixer after setting a pressure difference between the two liquids to ≤0.5MPa and the difference of volume amount between the two liquids to ≤3cc before injecting the two liquids in the metallic mold; and a force-feeding/injecting stage for force-feeding and injecting the conductive elastic layer forming material in the metallic mold. The developing roller is manufactured by the method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive member used for development, charging, transfer, cleaning, charge removal, etc. in an image forming apparatus employing an electrophotographic system such as a printer, a facsimile machine, and a copying machine, and a developing roller produced by the method. .

  When molding a synthetic resin with a mold, we expect that a molded product with high mold fidelity will be obtained, but in reality, the difference between the volume of the synthetic resin in the molten state and the volume in the cooled and solidified state, or cooling Due to the uneven temperature distribution in the molded product at the time, it is usual that the molded product is not always obtained according to the mold.

  For example, the injection molding method is characterized by the fact that complex shapes can be easily molded and the productivity is high, so the complexity of electronic and precision equipment that is required to be mass-produced with high precision is high. A wide range of articles, from shaped parts to everyday goods, are made by injection molding. However, in conventional injection molding, the occurrence of sink marks is unavoidable due to volume shrinkage when the resin moves from a molten state to a cooled state. In particular, sink marks tend to concentrate partially on the back surface or front surface of the thick portion. Further, at the location where the molten resin flowing in the mold joins, the fusion between the resins is incomplete and a weld line is generated.

  Since the sink marks and weld lines generated on the surface of the molded product significantly reduce the commercial value and may reduce the required molding accuracy, various measures have been conventionally taken.

As a conventional technique, in order to prevent the occurrence of a weld line, a mold provided with a heating device and a cooling device corresponding to the place where the weld line is generated is disclosed (for example, see Patent Document 1). Further, a method of applying a shearing force to a part of the molten resin in the mold (see, for example, Patent Document 2) and a method of applying ultrasonic waves to the flowing resin (see, for example, Patent Document 3) are disclosed. However, although these molds require the installation of special equipment and devices, the effects are not satisfactory.
JP-A-51-22759 JP-A-3-274127 Japanese Patent Laid-Open No. 4-90309

  An object of the present invention is to provide a method for producing a conductive member having no abnormal shape in the vicinity of a weld line or an injection hole due to merging of liquid rubber materials injected into a mold, and a developing roller manufactured by the method. That is.

  The object of the present invention is achieved by the following configurations.

  (1) In a method for manufacturing a conductive member, in which a conductive elastic layer is formed on the outer periphery of a shaft core body using a mold, and a coating layer is formed on the outer periphery of the conductive elastic layer, the conductive elastic layer The forming material is a two-liquid mixed liquid silicone rubber, and before the two liquids are injected into the mold, the pressure difference between the two liquids is 0.5 MPa or less, and the volume difference between the two liquids is 3 cc or less. A method for producing a conductive member, comprising: a mixing step of pouring into a static mixer and mixing by the static mixer; and then a pumping / injecting step of pumping and injecting the conductive elastic layer forming material into the mold.

  (2) The method for producing a conductive member according to (1), wherein a linear velocity difference between the two liquids flowing into the two-liquid mixing static mixer is 0.02 m / s or less.

  (3) The method for producing a conductive member according to (1) or (2), wherein the liquid silicone rubber is formed from an addition reaction-crosslinking liquid silicone rubber.

  (4) A developing roller for an image forming apparatus, which is a conductive member manufactured by the manufacturing method according to any one of (1) to (3).

  According to the present invention, when the conductive elastic layer is formed using the two-component equivalent liquid silicone rubber, the pressure difference and volume difference (supply amount difference) between the two solutions are set in the above-described ranges. Thus, a manufacturing method can be obtained in which a conductive member in which the generation of weld lines is suppressed can be obtained. Furthermore, by making the linear velocity difference between the two liquids in the above-described range, a manufacturing method can be obtained in which a conductive member in which the generation of weld lines is further suppressed can be obtained.

  Moreover, according to this invention, it becomes possible to provide the developing roller manufactured by the said manufacturing method.

  The present invention provides a method for producing a conductive member in which a conductive elastic layer is formed on the outer periphery of a shaft core body using a mold, and a coating layer is formed on the outer periphery of the conductive elastic layer. The layer forming material is a two-component liquid silicone rubber, and before the two components are injected into the mold, the pressure difference between the two components is 0.5 MPa or less, and the volume difference between the two components is 3 cc or less. A method of producing a conductive member comprising: a mixing step of pouring into a static mixer and mixing by the static mixer; and then a pumping / injecting step of pumping and injecting the conductive elastic layer forming material to the mold It is. Furthermore, the linear velocity difference between the two liquids flowing into the two-liquid mixing static mixer is preferably 0.02 m / s or less.

  Next, the configuration of the developing roller of the present invention will be described. The developing roller of the present invention includes, for example, a conductive shaft core 114a, a conductive elastic layer 114b concentrically formed on the outer periphery of the shaft core 114a, and the conductive elastic layer as shown in FIG. It has the coating layer (surface layer) 114c which is a resin layer formed on the outer periphery of 114b.

  The conductive shaft core 1 used in the present invention is, for example, a cylinder having a carbon steel alloy surface with industrial nickel plating having a thickness of 5 μm. As other materials constituting the conductive shaft core 1, for example, metals such as iron, aluminum, titanium, copper and nickel, alloys such as stainless steel, duralumin and bronze containing these metals, carbon black and carbon fibers It is also possible to use a known material that is rigid and exhibits electrical conductivity, such as a composite material obtained by platy-solidifying. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity besides the column shape.

  A conductive elastic layer is formed on the outer periphery of the conductive shaft core. A preferable material for forming the conductive elastic layer includes a silicone rubber polymer blended with carbon black as a conductive filler. Both ends of the conductive shaft core body 114a in which a vulcanized adhesive type silicone rubber primer is applied very thinly on the surface of a cylindrical mold whose inner diameter is appropriately selected with respect to the required outer diameter of the elastic layer From one side in the length direction of the shaft core, and a mixture of the above silicone rubber polymer with carbon black or the like as a conductive filler. It is injected at 10 cc / s and is heated and cured at a temperature of 100 ° C. to 150 ° C. for 3 to 60 minutes as primary curing to obtain a shaft core body and a conductive elastic layer disposed on the outer periphery thereof in a cylinder. be able to. In this case, the primary curing means that the conductive elastic forming material is cured to such an extent that the conductive elastic layer can be removed from the mold without significantly losing its shape, and further, the elastic layer is destroyed by curing in the mold. This refers to curing the rubber within a range that does not cause any problems. Thereafter, the conductive elastic layer having a thickness of 2 to 5 mm can be obtained by cooling from outside the cylindrical mold and further removing the mold.

  In the present invention, the pressure difference between the two liquids flowing into the two-liquid mixing static mixer is 0.5 MPa or less, preferably 0.2 MPa or less. Moreover, it is preferable that the pressure concerning each of 2 liquids is 5-15 Mpa.

  In the present invention, the volume difference between the two liquids flowing into the two-liquid mixing static mixer is 3 cc or less. When the volume difference exceeds 3 cc, the difference in mixing amount between the two liquids increases, resulting in poor mixing. The supply amount of each of the two liquids is preferably 20 to 50 cc.

  In the present invention, the linear velocity difference between the two liquids flowing into the two-liquid mixing static mixer is 0.02 m / s or less. When the linear velocity difference exceeds 0.02 m / s, mixing at the two-liquid interface becomes non-uniform. The linear velocity of each of the two liquids is preferably 0.02 to 0.05 m / s.

  The addition reaction cross-linkable liquid silicone rubber used has excellent heat resistance and cold resistance, and exhibits good compression recovery characteristics over a wide temperature range, weather resistance, ozone resistance, corona resistance, electrical characteristics, heat resistance oil resistance, chemical resistance, It is a material with excellent hot water resistance, and these characteristics are determined by the type and blending method of the silicone polymer, filler, additive and the like.

  This silicone rubber polymer contains, for example, organopolysiloxane and organohydrodiene polysiloxane, and can be used by appropriately mixing with an inorganic filler, a platinum-based catalyst, and a curing reaction retarder.

  Organopolysiloxane is a base polymer of a silicone rubber raw material having a linear structure or a branched structure, and the molecular weight is not particularly limited, but is preferably 100,000 or more and 1,000,000 or less, and the average molecular weight is preferably about 500,000. Furthermore, from the viewpoints of processing characteristics and characteristics of the resulting silicone rubber composition, the viscosity of the organopolysiloxane at 25 ° C. is preferably 10 Pa · s or more as a lower limit, more preferably 50 Pa · s or more, and 300 Pa as an upper limit. · S or less is preferable, and 250 Pa · s or less is more preferable.

  The molecular terminal group of the organopolysiloxane is a site that reacts with the active hydrogen of the organohydrogenpolysiloxane to form a crosslinking point, and the type thereof is not particularly limited, but a triorganosilyl group, for example, a trimethylsilyl group, Examples include diphenylmethylsilyl group, diphenylmethylsilyl group, dimethylvinylsilyl group, and methylphenylvinylsilyl group. For reasons such as high reactivity with active hydrogen, at least one of vinyl group and allyl group is preferable. A vinyl group is particularly preferred.

  The organohydrogenpolysiloxane is required to have at least two hydrogen atoms directly bonded to a silicon atom in one molecule, which is crosslinked by an addition reaction between the hydrogen atom and an alkenyl group in the organopolysiloxane. Is necessary to form and cure the composition. The molecular weight of the polyorganohydrodiene polysiloxane is not particularly limited and may be from 1,000 to 10,000, but a relatively low molecular weight of 1,000 or more and 5,000 or less is preferable in order to appropriately perform the curing reaction.

  The silicone rubber raw material clay containing the necessary fillers is not particularly limited, but is preferably 10 Pa · s or more from the viewpoint of preventing material leakage by suppressing the fluidity of the material to some extent, and there is a weld between the injection gates. From the viewpoint of avoiding the problem of molding processability such as occurrence, 300 Pa · s or less is preferable.

  Poor mixing appears as a weld line on the conductive elastic roller. When the weld line is generated, a slight depression is formed on the elastic layer, resulting in an image defect.

  Next, an example of a process cartridge using the developing roller of the present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing a schematic configuration of an image forming apparatus having a process cartridge using the developing roller of the present invention.

  The process cartridge includes a developer carrying member that carries a developer in a state of being in contact with or pressed against a photosensitive drum as a latent image carrying body that carries a latent image, and the developer carrying member develops the photosensitive drum on the photosensitive drum. A process cartridge that visualizes a latent image as a developer image by applying a toner as a developer, and includes a photosensitive drum 21 as a latent image carrier, a charging device 22, a developer carrier member 25, a developing blade 27, and a developing container 34. The cleaning blade 30 is provided, and the developing roller of the present invention is used as the developer carrying member 25. In the process cartridge, the photosensitive drum 21 rotates in the direction of arrow A, is uniformly charged by a charging device 22 for charging the photosensitive drum 21, and is a laser beam that is an exposure unit that writes an electrostatic latent image on the photosensitive drum 21. 23, an electrostatic latent image is formed on the surface. The electrostatic latent image is developed by being provided with a toner 28 as a developer by a developing device 24 that is disposed in proximity to the photosensitive drum 21 and is held in a process cartridge that can be attached to and detached from the image forming apparatus main body. Visualized as a toner image.

  Development is so-called reversal development in which a toner image is formed on the exposed portion. The visualized toner image on the photosensitive drum 21 is transferred onto a paper 33 as a recording medium by a transfer roller 29. The paper 33 to which the toner image has been transferred is fixed by the transfer device 32, discharged outside the device, and the printing operation ends.

  On the other hand, the untransferred toner remaining on the photosensitive drum 21 without being transferred is scraped off by the cleaning blade 30 and stored in the waste toner container 31, and the cleaned photosensitive drum 21 repeats the above-described operation.

  The developing device 24 includes a developing container 34 that contains a non-magnetic toner 28 as a one-component developer, and a developer carrying member that is located in an opening extending in the longitudinal direction in the developing container 34 and is opposed to the photosensitive drum 21. The electrostatic latent image on the photosensitive drum 21 is developed and visualized.

  The developer carrying member 25 is in contact with the photosensitive drum 21 with a contact width, and is rotated in the direction of arrow B. In the developing device 24, the supply roller 26 is in contact with the contact portion of the developing blade 27 with the surface of the developer carrying member 25 in the developing container 34 on the upstream side in the rotation direction of the developer carrying member 25, and It is rotatably supported.

  As the structure of the supply roller 26, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon or nylon are planted on the core metal, the toner 28 is supplied to the developer carrying member 25 and the undeveloped toner is stripped It is preferable from the point of taking. In the present embodiment, a supply roller 26 having a diameter of 14 mm provided with a polyurethane foam on a metal core is provided.

  As the contact width of the supply roller 26 with respect to the developer carrying member 25, 1 to 8 mm is effective, and it is preferable that the developer carrying member 25 has a relative speed at the contact portion. In the present embodiment, the contact width is set to 2 mm, and is driven to rotate at a predetermined timing by a driving means (not shown).

  Hereinafter, the present invention will be described in more detail using specific examples. These examples do not limit the present invention in any way.

[Example 1]
A core metal having an outer diameter of 8 mm is placed concentrically in a cylindrical mold having an inner diameter of 16 mm. Next, the pressure applied to each of liquid A and liquid B of liquid conductive silicone rubber (volume resistivity 10E7 Ωcm product manufactured by Toray Dow Corning Co., Ltd.) is 9.7 MPa for liquid A, 10 MPa for liquid B, and the pressure difference is 0.3 MPa. Each linear velocity is set to 0.05 m / s, each supply amount is set to 42 cc, poured into a static mixer, and the conductive elastic layer forming material obtained by mixing the two liquids is pumped and cast. A conductive roller was obtained. A urethane paint (Nipporan N5033 manufactured by Nippon Polyurethane Co., Ltd.) was diluted with methyl ethyl ketone so that the solid content concentration was 10%. To 100 parts by mass of the urethane paint solid content, 50 parts by mass of carbon black (# 7360SB Tokai Carbon Co., Ltd.) is added as a conductive agent, and a hardener (Coronate L made by Nippon Polyurethane Co., Ltd.) is added to the well dispersed. Add 10 parts by weight, further dilute with 200 parts by weight of methyl ethyl ketone, dip coat the stirred paint on the conductive roller, dry in an oven at 80 ° C. for 15 minutes, cure in an oven at 140 ° C. for 4 hours, A developing roller was obtained. The resulting developing roller was incorporated into a process cartridge and mounted on a laser beam printer, and images were taken out in a normal environment. As a result, good images were obtained. The image results associated with the weld line are summarized in Table 1.

[Example 2]
A developing roller is obtained in the same manner as in Example 1 except that the linear velocity of the liquid A flowing into the two-liquid mixing static mixer is 0.03 m / s, the linear velocity of the liquid B is 0.04 m / s, and the pressure is 10 MPa. Evaluation was conducted in the same manner as in Example 1.

Example 3
A developing roller is obtained in the same manner as in Example 1 except that the volume of the two liquids flowing into the static mixer for mixing two liquids is 40 cc for Liquid A, 41 cc for Liquid B, and 10 MPa. did.

[Comparative Example 1]
A developing roller was obtained in the same manner as in Example 1, except that the pressure of the two liquids flowing into the two-liquid mixing static mixer was 10 MPa for liquid A and 9.2 MPa for liquid B. The obtained developing roller was incorporated into a process cartridge and mounted on a laser beam printer, and as a result of image output in a normal environment, an image defect due to the developing roller pitch occurred.

[Comparative Example 2]
The pressure of the two liquids flowing into the two-liquid mixing static mixer is 8 MPa for liquid A and 9 MPa for B liquid, the linear speed of liquid A flowing into the static mixer for two-liquid mixing is 0.03 m / s, and the linear speed of liquid B is A developing roller was obtained in the same manner as in Example 1 except that the amount was 0.06 m / s, and was evaluated in the same manner as in Comparative Example 1.

[Comparative Example 3]
A developing roller was obtained in the same manner as in Example 3 except that the volume of the two liquids flowing into the two-liquid mixing static mixer was 39 cc for the A liquid and 43 cc for the B liquid.

  As is apparent from Table 1, in Example 1, the result that no weld line is generated is obtained by forming the pressure difference between the two liquids flowing into the two-liquid mixing static mixer at 0.5 MPa or less. It was.

  Moreover, in Example 2, the result that a weld line did not generate | occur | produce at all was obtained by shape | molding the linear velocity difference between the 2 liquids which flow into the static mixer for 2 liquid mixing below 0.02 m / s.

  In Example 3, the result that the weld line was not generated at all was obtained when the volume difference between the two liquids flowing into the two-liquid mixing static mixer was 3 cc or less.

  On the other hand, in Comparative Example 1, since the pressure difference between the two liquids was large, poor curing occurred, weld lines were generated, and image defects occurred.

  In Comparative Example 2, since the pressure difference and linear velocity difference between the two liquids were large, mixing at the two liquid interface was insufficient, weld lines were generated, and image defects were generated.

  In Comparative Example 3, the difference in volume between the two liquids was large, resulting in poor curing, weld lines, and image defects.

It is a figure which shows the basic composition of the developing roller of this invention. 1 is a schematic configuration diagram of an image forming apparatus having a process cartridge using a developing roller of the present invention.

Explanation of symbols

114a: shaft core 114b: conductive elastic layer 114c: coating layer (surface layer)
21: Image carrier (photosensitive drum)
22: Charging device 23: Laser light 24: Developing device 25: Developer carrying member (developing roller)
26: Supply roller 27: Developing blade 28: Developer (toner)
29: Transfer roller 30: Cleaning blade 31: Waste toner container 32: Fixing device 33: Paper

Claims (4)

  In the method for manufacturing a conductive member, in which a conductive elastic layer is formed on the outer periphery of the shaft core body using a mold, and a covering layer is formed on the outer periphery of the conductive elastic layer, the conductive elastic layer forming material includes: It is a two-component mixed liquid silicone rubber. Before pouring the two components into the mold, the pressure difference between the two components is 0.5 MPa or less, and the volume difference between the two components is 3 cc or less. A method for producing a conductive member comprising a mixing step of pouring and mixing by the static mixer, and then a pressure-feeding / injecting step of pressure-feeding and injecting the conductive elastic layer forming material to the mold.   The method for producing a conductive member according to claim 1, wherein a linear velocity difference between the two liquids flowing into the two-liquid mixing static mixer is 0.02 m / s or less.   The method for producing a conductive member according to claim 1, wherein the liquid silicone rubber is formed from an addition reaction cross-linkable liquid silicone rubber.   A developing roller for an image forming apparatus, which is a conductive member manufactured by the manufacturing method according to claim 1.