JP2002115714A - Manufacturing method for conductive foam body roller and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive foam body roller having homogeneous characteristics such as electric resistance, hardness, and foam shape and suited as a member for an image formation device, by a die foaming method. SOLUTION: In this manufacturing method for the conductive foam body roller having a process of setting a tubular preforming body, which is composed of a conductive rubber and formed by inserting a shaft therein, in a mold, pressure-vulcanizing, die drawing, and foaming, the preforming body having a belt film stuck in a place corresponding to the position of a mating face with the mold in the preforming body along its longitudinal direction is set in the mold and is pressure-vulcanized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method of manufacturing a conductive foam roller and an image forming apparatus, and more particularly, to a copier, a laser printer, and the like having uniform characteristics such as electric resistance, hardness, and bubble shape. A method for manufacturing a conductive foam roller suitably used as a member for an image forming apparatus such as an electrophotographic apparatus such as a facsimile or an electrostatic recording apparatus, and a conductive foam roller obtained by the method are mounted. The present invention relates to the image forming apparatus.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, image forming apparatuses such as electrophotographic apparatuses and electrostatic recording apparatuses are used for charging, developing, transferring, supplying toner, and cleaning. Conductive polymer materials have attracted attention as components for such components, and include charging rollers, developing rollers, transfer rollers,
It is used in the form of a conductive roller having elasticity such as a toner supply roller and a cleaning roller. As the conductive roller, in order to obtain a high-quality image, a foam of a low-hardness rubber composition having appropriate conductivity is used. The method for producing the foam is generally classified into two types: an in-mold foaming method and a free foaming method. In the case of the conductive foam roller, a fine and uniform cell (bubble) diameter is required. In-mold foaming has been performed.

[0003] When a conductive foam roller is produced by an in-mold (mold) foaming method, a joint between two molds always exists, since the first mold and the second mold are generally used in combination. Rubber elastic body, a conductive rubber foam forming material containing a chemical foaming agent and a conductivity imparting agent, when foaming is performed using such a mold,
The material leakage (material flow) occurs at the joint, and the influence of the material flow appears on the foam after demolding. For example, abnormalities occur at the mold mating surface in electric resistance, hardness, bubble shape, and the like. It's easy to do. Therefore, in the case of a conductive foam roller in which it is essential that these properties are uniform, nonuniformity of the properties becomes a serious problem. Therefore,
In order to prevent such non-uniformity of characteristics, the conventional (1) mold is manufactured to be larger than an actual product by previously considering the amount of grinding (grinding) to a level where the influence of the material flow is not a problem. In general, the method of adjusting the filling amount to the material, reducing the amount of protrusion and the material flow due thereto, and (3) increasing the pressing force to prevent the material flow from the mating surface, is used alone or in general. It is done in combination. However, in the above-mentioned method (1), the influence cannot be removed unless considerable cutting is performed, so that the loss of relatively expensive materials is large, and it is unavoidable that the method is economically disadvantageous. Further, in the method (2), since a foam having a different foaming state is obtained due to a slight difference in the filling amount, the range in which the foam can be prepared is extremely narrow, and the management thereof is very troublesome. Furthermore, the method of (3)
There is a problem that equipment becomes large and expensive.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a conductive foam roller by using an in-mold foaming method by using a conductive rubber foam-forming material under such circumstances. It is an object of the present invention to provide a method for suppressing the flow of material from a surface and efficiently producing a conductive foam roller having uniform properties such as electric resistance, hardness, and cell shape.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, the present inventors have found that the positions corresponding to the positions of the mating surfaces of the molds in the tubular preform formed of the foam-forming material. A place where a band-shaped film is stuck along the longitudinal direction of the preformed body in a mold, set in a mold, press-vulcanized, and then demolded and foamed to achieve the object. I found The present invention has been completed based on such findings. That is, the present invention comprises a conductive rubber foam forming material,
A method for producing a conductive foam roller having a process of setting a tubular preform having a shaft inserted therein, and vulcanizing under pressure, vulcanizing and foaming after pressurizing, wherein the mold in the preform is molded In the place corresponding to the position of the mating surface, set a band-shaped film attached along the longitudinal direction of the preform in the mold,
An object of the present invention is to provide a method for producing a conductive foamed roller characterized by performing pressure vulcanization. Further, the present invention also provides an image forming apparatus equipped with the conductive foam roller obtained by the above manufacturing method.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a conductive foam roller of the present invention, a conductive rubber foam forming material (hereinafter sometimes simply referred to as a foam forming material) is used as a material. This foam-forming material is usually a rubber elastic body,
It contains a chemical foaming agent, a conductivity-imparting material, and optionally a rubber additive such as a vulcanizing agent, a vulcanization accelerator, an oil, a plasticizer, zinc white, stearic acid, calcium carbonate, and magnesia. As the rubber elastic body, for example, E
PDM rubber (ethylene propylene diene rubber), urethane rubber, nitrile rubber, silicone rubber, chloroprene rubber, epichlorohydrin rubber, butadiene rubber, styrene butadiene rubber, isoprene rubber, natural rubber, butyl rubber, acrylic rubber, and the like. They may be used, or two or more kinds may be used in combination.
Among them, EPDM rubber and chloroprene rubber are particularly preferable because they can obtain dense and uniform foam cells and have good durability such as heat resistance.

The chemical foaming agent is not particularly limited, and can be appropriately selected from known inorganic foaming agents and organic foaming agents. Here, examples of the inorganic blowing agent include sodium hydrogen carbonate, ammonium hydrogen carbonate, sodium borohydride, and the like. Examples of the organic blowing agent include azodicarbonamide, azobisisobutyronitrile, and barium azodicarboxy. rate,
Dinitrosopentamethylenetetramine, p, p'-oxybis (benzenesulfonylhydrazide), p-toluenesulfonylhydrazide and the like. These chemical foaming agents may be used alone or in combination of two or more. Among them, in particular, p, p'-
Oxybis (benzenesulfonyl hydrazide) and azodicarbonamide are preferable because a dense and uniform foam cell can be obtained. The amount of the chemical foaming agent is usually in the range of 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the rubber elastic body. On the other hand, examples of the conductivity-imparting agent include carbon black; metal powders such as nickel and copper; metal oxide powders such as tin oxide, titanium oxide and zinc oxide; and other conductive metal double oxide powders; It can be used by appropriately selecting from ionic conductive agents such as perchlorate, alkyl sulfate, carboxylate, and borofluoride. These conductivity imparting agents may be used alone or in combination of two or more. Further, the compounding amount can be appropriately selected according to the type of the conductivity-imparting agent so that a conductive rubber foam having a desired specific resistance value is obtained.

[0008] The vulcanizing agent can be appropriately selected from known vulcanizing agents, for example, sulfur and peroxide, depending on the type of the rubber elastic body. Next, a method of manufacturing a conductive foam roller using the foam forming material will be described. First, a foam-forming material containing the above components is prepared. At this time, the rubber elastic body, the conductivity-imparting agent, and other additives except the chemical foaming agent and the vulcanizing agent are kneaded at a temperature of about 70 to 130 ° C., and then kneaded at a temperature of about 50 to 90 ° C. It is preferable to knead a chemical foaming agent and a vulcanizing agent at a low temperature to suppress early vulcanization and early foaming. The kneading is usually performed using a roll, a kneader, a mixer or the like. Next, the foam-forming material thus prepared is extruded into a tube shape by, for example, an extruder. In this case, the extrusion molding temperature is advantageously set to a temperature lower than the vulcanization temperature or the foaming temperature, for example, about 70 to 100 ° C., in order to suppress early vulcanization and early foaming.

Next, after cutting this tube-shaped molded body to a predetermined size with a cutter or the like, a shaft (dummy shaft) is inserted into this to form a preformed body. In the present invention, the pre-formed body thus produced is set in a mold, and subjected to heat treatment and pressure vulcanization, but before being set in the mold, a pre-molding of the pre-formed body in the pre-formed body is performed. It is necessary to attach a band-shaped film along the longitudinal direction of the preform at a location corresponding to the position of the mating surface. In this way, by attaching the belt-like film, it is possible to prevent material flow from the seam of the mold due to foaming when set in the mold, heat-treated and vulcanized under pressure, and as a result Thus, a conductive foam roller having uniform properties such as electric resistance, hardness, and bubble shape can be obtained. The material of the belt-shaped film is not particularly limited as long as it has resistance to a heating temperature during pressure vulcanization and has releasability from the obtained conductive rubber foam. Can be used. Examples of such a film include paper such as glassine paper, coated paper and laminated paper, and plastic films such as polyethylene terephthalate film. These papers and plastic films are in contact with the conductive rubber foam,
If necessary, a release agent such as a silicone resin can be applied.

In the present invention, the strip film is
It is preferable that the thickness be in the range of 10 to 300 μm and the width be 3 mm or more. If the thickness of the film is less than 10 μm, handling is troublesome, and if it exceeds 300 μm, a large step is generated in the conductive rubber foam, which is not preferable. For this reason, a more preferable thickness is 20 to 100.
It is in the range of μm. On the other hand, if the width of the film is less than 3 mm, it is difficult to set the mold on the mating surface. A more preferred width is in the range of 10 to 70 mm. In this way, after setting the band-shaped film attached to the place corresponding to the position of the mating surface of the mold in the preform in the mold, heat treatment is performed at a temperature of about 150 to 200 ° C. for about 10 to 30 minutes. By doing so, the foaming agent is decomposed and pressure vulcanization is performed. Thereafter, the mold is removed and foamed to form a conductive rubber foam. The affixed band-shaped film is usually spontaneously peeled off during the foaming.

FIG. 1 is an explanatory view showing an example of a state in which a band-shaped film is stuck at a position corresponding to a position of a mating surface of a mold in a preform and set in the mold. As shown in the figure, in the tubular preform 1 into which the shaft 2 has been inserted, strip-shaped films 5 and 5 'are provided at positions corresponding to the positions of the mating surfaces 3 of the first mold 4 and the second mold 4'. Are attached, and a preform formed by attaching the band-shaped film is set in the molds 4 and 4 ′. Next, the shaft (dummy shaft) of the conductive rubber foam thus formed is removed and secondary vulcanization is performed, or the conductive rubber foam is inserted while the shaft (dummy shaft) is inserted. After secondary vulcanization, the shaft (dummy shaft) is removed. This secondary vulcanization is usually 140 to 2
This is performed at a temperature of about 00 ° C. for about 0.5 to 10 hours.

Next, the shaft with the adhesive is inserted into the conductive rubber foam and bonded by heating. Then, the shaft is polished by a known method so as to have a desired roller diameter. A foamed foam roller is obtained. Examples of the shaft used at this time include a metal member obtained by plating a steel material such as sulfur free-cutting steel with zinc or the like, and a metal member such as aluminum, stainless steel, and magnesium alloy. As the adhesive, a conventionally known adhesive, for example, a urethane-based adhesive or an ethylene-vinyl acetate copolymer-based adhesive can be used. As the form of the adhesive, any of a hot melt type, an emulsion type, a solution type, a two-part type, and the like can be used, but a hot melt type is preferable in terms of operability and adhesiveness. Further, an adhesive made of a conductive paint can also be used. The temperature at the time of heat bonding depends on the type of the adhesive, but is usually in the range of 100 to 160 ° C.

The conductive foam roller thus obtained has uniform properties such as electric resistance, hardness, and bubble shape, and is suitably used as a member for an image forming apparatus. Further, the image forming apparatus of the present invention uses the conductive foam roller obtained by the above-described method of the present invention as a conductive member, specifically, a charging member, a developing member, a transfer member, and a toner supplying member. And a cleaning member. Next, an example in which the conductive foam roller is mounted on an image forming apparatus as a transfer member will be described. FIG. 2 is an explanatory view showing an example of a transfer device in an image forming apparatus using a conductive foam roller (transfer member) obtained by the method of the present invention, and a conductive member provided with a shaft (not shown). A conductive foam roller (transfer member) 6 is brought into contact with an image forming body (photoreceptor) 7 via a recording medium (transfer material) 8 such as paper, and the conductive foam roller (transfer member) 6
The toner (developer) on the image forming body 7 is transferred to the recording medium 8 by applying a voltage from the power source 9 between the image forming body 7 and the image forming body (photosensitive body) 7 to generate an electric field therebetween. Things.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 For 100 parts by weight of EPDM (ethylene propylene diene rubber), 48 parts by weight of carbon black, 38 parts by weight of calcium carbonate, 60 parts by weight of paraffin oil, OBSH
[P, p'-oxybis (benzenesulfonylhydrazide), decomposition temperature 159 ° C] 6 parts by weight, zinc white 3 parts by weight,
2 parts by weight of stearic acid, 1 part by weight of a vulcanization accelerator M (2-mercaptobenzothiazole) and 1.5 parts by weight of sulfur were blended and kneaded with a kneader to prepare an unvulcanized foam-forming material. . This foam-forming material is cut into a ribbon shape and supplied to a 90 mmφ extruder (manufactured by Miba Seisakusho) to produce a tube-shaped unvulcanized rubber material (inner diameter about 4 mm, outer diameter 20 to
21 mm and a length of about 240 mm). Through this, a dummy shaft (diameter: 4 mm) is passed through, and a place having a thickness of 34 μm and a width of 1
A 5 mm strip-shaped polyethylene terephthalate film (manufactured by Teijin Limited) was attached to prepare a preform. Then, this was set in a mold and heated at 175 ° C. for 18 hours.
By heating for minutes, the blowing agent OBSH was decomposed and pressure vulcanization was performed. Then, the conductive rubber foam was obtained by demolding and foaming. On this occasion,
At the time of foaming, the belt-like polyethylene terephthalate film
Peeled off naturally.

Next, after removing the dummy shaft,
Perform secondary vulcanization at 180 ° C for 3 hours for shape stability.
It was left to reach room temperature. Next, a metal shaft (diameter 6 mm) to which an adhesive is applied is inserted, and heated and bonded at 120 ° C. for 70 minutes, and then, a polishing process is performed so that the roll diameter becomes 20 mm. Was prepared. Table 1 shows the physical properties of the conductive foam roller. Comparative Example 1 A conductive foam was prepared in the same manner as in Example 1 except that the polyethylene terephthalate film was not attached to a position corresponding to the position of the mating surface of the mold in the preform. A roller was made. Table 1 shows the physical properties of the conductive foam roller.

[0016]

[Table 1]

[Note] 1) Bubbles: Observed with an optical microscope. 2), 3) Average hardness and hardness variation: Measured with an Asker C hardness meter. The difference between the average value, the maximum value, and the minimum value when measuring 20 points in the circumferential direction while rotating the roller at the axial center of the roller. 4), 5) Average resistance, variation in resistance: resistance measuring instrument R8
340 (manufactured by Advantest Corporation). The roller is brought into contact with a counter rotating electrode made of metal, and while the roller is rotating, a voltage of 100 V is applied to measure the resistance value (R) at 36 points in the circumferential direction. The average value [(ΣlogR) /
n], the difference between the maximum value and the minimum value [logR _(max) -logR
_(MIN) ]. In Table 1, the common logarithm (log
R).

[0018]

According to the present invention, when a conductive foam roller is manufactured by the in-mold foaming method, a film is attached to a position corresponding to the position of the mating surface of the mold in the tubular preform, and the film is attached. Is set in the mold,
By heating and vulcanizing under pressure, material flow from the mating surface of the mold is suppressed, and a conductive foam roller having uniform properties such as electric resistance, hardness, and bubble shape can be manufactured. This conductive foam roller is used in copiers,
It is suitably used as a member for an image forming apparatus such as an electrophotographic apparatus such as a laser printer or a facsimile or an electrostatic recording apparatus.

[Brief description of the drawings]

FIG. 1 shows an example of a method of manufacturing a conductive foam roller according to the present invention, in which a band-shaped film is stuck to a location corresponding to a position of a mating surface of a mold in a preform and set in the mold. FIG.

FIG. 2 is an explanatory diagram showing an example of a transfer device in an image forming apparatus using a conductive foam roller obtained by the method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tubular preform 2 shaft 3 mold mating surface 4 first mold 4 ′ second mold 5, strip film 6 conductive foam roller 7 image forming body (photoconductor) 8 recording medium (transfer material) ) 9 Power supply

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 15/08 501 G03G 15/08 501D 4F203 15/16 103 15/16 103 21/10 B29K 105: 04 // B29K 105 : 04 105: 20 105: 20 B29L 31:32 B29L 31:32 G03G 21/00 312 F term (reference) 2H003 BB11 CC05 2H032 AA05 BA23 2H034 BC03 BC04 2H077 AC04 AD06 FA16 FA22 FA25 3J103 AA02 AA13 AA32 EA07 EA07 EA07 EA07 EA20 FA15 FA18 GA02 GA52 GA57 GA58 GA60 HA03 HA05 HA12 HA15 HA18 HA20 HA32 HA33 HA37 HA52 HA53 4F203 AD05 AD15 AE03 AG14 AG20 AH04 AH33 DA11 DB01 DJ05 DK02 DK07 DW21

Claims (6)

[Claims] 1. A conductive material comprising a process in which a tubular preform made of a conductive rubber foam forming material and having a shaft inserted therein is set in a mold, vulcanized under pressure, and then demolded and foamed. In the method for manufacturing a porous foam roller, a pre-formed body having a band-shaped film attached along the longitudinal direction of the pre-formed body at a position corresponding to the position of the mating surface of the mold is set in the mold, and A method for producing a conductive foamed roller, comprising pressure vulcanization. 2. The method for producing a conductive foam roller according to claim 1, wherein the conductive rubber foam-forming material contains a rubber elastic body, a chemical foaming agent, and a conductivity imparting agent. 3. The belt-like film has a thickness of 10 to 300 μm.
3. The method for producing a conductive foam roller according to claim 1, wherein the width is 3 mm or more. 4. After vulcanizing the preformed body under pressure, demold and foam to form a conductive rubber foam, remove the shaft, perform secondary vulcanization, and then perform the main shaft with adhesive. The method for producing a conductive foam roller according to claim 1, 2 or 3, wherein the conductive foam roller is inserted by heating. 5. The pre-molded article is vulcanized under pressure, demolded and foamed to form a conductive rubber foam, then subjected to secondary vulcanization, and then the shaft is removed and a book with an adhesive is attached. 4. The method for producing a conductive foam roller according to claim 1, wherein the shaft is inserted and heated and bonded. 6. An image forming apparatus equipped with a conductive foam roller obtained by the method according to claim 1.