JP5706638B2 - Rubber roller and method of manufacturing rubber roller - Google Patents

Description

  The present invention relates to a rubber roller used in an image forming apparatus such as an electrophotographic copying apparatus, a printer, and an electrostatic recording apparatus, and more particularly to a rubber roller and a method for manufacturing the rubber roller that eliminates the twist of the roller rubber.

  The image forming apparatus charges the surface of the rotating photosensitive drum 30 with a charging roller 31 as shown in FIG. 4 and irradiates the photosensitive drum 30 with light corresponding to the image signal by the exposure device 32 to form an electrostatic latent image. Then, the toner of the developing device 33 is moved to the contact portion of the photosensitive drum 30 via the developing roller 34, and the toner is attached to the electrostatic latent image portion formed on the surface of the photosensitive drum 30, and this is transferred to the transfer roller. 35, the toner image is transferred to a recording medium 36 such as paper pressed against the photosensitive drum 30 by electrostatic force, and then the toner is melted and fixed by a fixing device 37 by heat or pressure. Further, the toner remaining on the photosensitive drum 30 is scraped off and collected by the cleaning blade 38.

  The charging roller 31, the developing roller 34, and the transfer roller 35 used in this image forming apparatus are mainly formed in a three-layer structure as disclosed in Patent Documents 1-5.

  FIG. 5 shows a rubber roller 40 having a three-layer structure. A sponge layer 42 as a foamed elastic body is formed on a shaft 41, a solid layer 43 as a resistance adjusting layer is formed on the outer periphery thereof, and the outer periphery thereof is further shown. A coating layer 44 as a protective layer is formed on the rubber roller 40.

  When manufacturing the rubber roller 40, as shown in Patent Document 2, the sponge layer 42 is extruded into a tube shape by an extruder, vulcanized, and then press-fitted into a shaft. The solid layer 43 and the coating layer 44 are coated on the outer periphery of the film, or the sponge layer 42 and the solid layer 43 are formed by extrusion at the same time as shown in Patent Document 3, or as shown in Patent Documents 4 and 5. Thus, the sponge layer 42 and the solid layer 43 are formed using a mold.

JP-A-8-234595 JP 2009-237532 A JP 2009-80175 A JP 2007-178752 A JP 2007-264294 A

  However, when the sponge layer 42 and the solid layer 43 are formed using a mold as in Patent Documents 4 and 5, there is a problem that the manufacturing cost increases. Further, when the sponge layer 42 and the solid layer 43 are formed by coextrusion as in Patent Document 3, there is a problem that hardness unevenness and resistance value unevenness occur.

  Patent Document 2 has an advantage that the sponge layer 42 is extruded into a tube shape, vulcanized, and press-fitted into the shaft, so that there is an advantage that it can be easily manufactured without incurring manufacturing costs, but the solid layer 43 is formed by coating. However, it is difficult to increase the layer thickness.

  Therefore, it is promising that the solid layer 43 is formed into a tube shape by an extruder and covered with the sponge layer 42 press-fitted into the shaft 41. However, the simple layer cannot prevent the solid layer 43 from being twisted. . Also, if the adhesive is applied to the sponge layer 42 to cover the solid layer 43 in order to prevent kinking, the sponge layer 42 and the solid layer 43 are bonded with the adhesive, so that kinking can be prevented. As a result, the problem of uneven resistance occurs.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and in a rubber roller manufactured by sequentially inserting a sponge layer and a solid layer formed by extrusion molding into a shaft, even if no adhesive is applied, the solid layer An object of the present invention is to provide a rubber roller that can prevent wrinkles and a method of manufacturing the same.

In order to achieve the above object, the invention according to claim 1 is a rubber roller in which at least a sponge layer and a solid layer are sequentially formed concentrically on a shaft, and the shaft is inserted into the sponge layer formed in a tube shape, the solid layer formed on the tubular sponge layer is fitted without using an adhesive, the thickness of the solid layer is, 1.0 mm or more, a rubber roller, characterized in that it is 2.0mm or less.

A second aspect of the present invention, the thickness of the sponge layer is more than 3.5 mm, a rubber roller according to claim 1, characterized in that at 4.5mm or less.

According to a third aspect of the present invention, in the method of manufacturing a rubber roller in which at least a sponge layer and a solid layer are sequentially formed on a shaft in a concentric manner, the sponge layer is formed into a tube shape by extrusion molding, and the solid layer is thickened by extrusion molding. The tube is formed into a tube shape having a thickness of 1.0 mm to 2.0 mm , and after the shaft is press-fitted into the tube-like sponge layer, the tube-like solid layer is fitted into the sponge layer without using an adhesive. This is a method for manufacturing a rubber roller.

According to a fourth aspect of the present invention, after the shaft is press-fitted into the sponge layer, the outer periphery of the sponge layer is polished to a predetermined diameter, and the solid layer is formed into a tube shape having an inner diameter smaller than the outer diameter of the polished sponge layer. The rubber roller manufacturing method according to claim 3 , wherein the tube-shaped solid layer is expanded and fitted into the sponge layer by extrusion molding.

The invention of claim 5, the value obtained by subtracting the inner diameter of the solid layer from the outer diameter of the sponge layer, beyond the 0 mm, according to claim 4, characterized in that formed below the size 2.0mm It is a manufacturing method of a rubber roller.

The invention according to claim 6 is the method for producing a rubber roller according to claim 4 or 5 , wherein a coating layer is applied and baked on the outer periphery of the solid layer.

  According to the present invention, even if no adhesive is applied, an excellent effect of preventing the solid layer from being twisted is exhibited.

It is sectional drawing of the rubber roller which shows one embodiment in this invention. It is a figure which shows the manufacturing process of the rubber roller of this invention. In this invention, it is a figure which shows the relationship between the thickness (mm) of a solid layer, and the Asker C hardness (degree) of a rubber roller. It is a figure which shows the outline of the image forming apparatus in which a rubber roller is used. It is sectional drawing of the conventional rubber roller.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows a sectional view of a rubber roller 10 of the present invention.

  In FIG. 1, a shaft 11 is press-fitted into a sponge layer 12 obtained by extruding an adhesive foam rubber into a tube shape, and the outer periphery of the sponge layer 12 is polished. A rubber layer 10 is manufactured by fitting a solid layer 13 formed by extruding rubber with a tube into a tube shape and applying and baking a coat layer 14 on the outer periphery of the solid layer 13. At this time, the solid layer 13 may be fitted into the sponge layer 12 immediately after being extruded, or may be fitted into the sponge layer 12 that has been extruded in advance.

  The shaft 11 is made of a pipe having an outer diameter of Φ25.0 mm, for example.

The sponge layer 12 is made of a semiconductive rubber obtained by adding a conductive material to a foamed rubber or a non-adhesive foamed rubber. As the foamed rubber, foamed NBR (nitrile rubber), foamed EPDM (ethylene-propylene rubber), or the like can be used. As foamed rubber with tackiness, use is made of foamed NBR (nitrile rubber) or foamed EPDM (ethylene-propylene rubber) to which tackifiers such as phenol resin, coumarone resin, acetylene resin, and terpene are added. it can. The thickness of the sponge layer 12 is 3.5 to 4.5 mm when the total thickness with the solid layer 13 is 5.5 mm. The resistance value of the sponge layer 12 is about 5 × 10 ⁶ Ω.

  The solid layer 13 is made of a semiconductive rubber obtained by adding a conductive material to an adhesive rubber or a non-adhesive rubber. As the rubber, NBR (nitrile rubber), EPDM (ethylene-propylene rubber), or the like can be used. As the rubber having tackiness, a rubber obtained by adding a tackifier such as phenol resin, coumarone resin, acetylene resin, terpene resin to NBR (nitrile rubber) or EPDM (ethylene-propylene rubber) can be used. As the solid layer 13, resins such as aliphatic hydrocarbon resins and aromatic hydrocarbon resins can also be used.

Further, the solid layer 13 only needs to have adhesiveness on the inner surface in contact with the sponge layer 12, and gives a frictional force by surface roughness of the inner surface, grooves, embossing, or roughening the surface shape of the sponge layer. You may do it. If the thickness of the solid layer 13 is 1.0 mm or more, it is effective against twisting. When used as a transfer roller, the thickness of the solid layer 13 is 1.0 to 2.0 mm because of its function (securing the transfer nip). Is preferred. The resistance value of the solid layer 13 is about 1 × 10 ⁷ Ω.

  The coefficient of static friction between the sponge layer 12 and the solid layer 13 is preferably 3.0 or more.

The coating layer 14 is coated to improve the cleaning properties of the toner and paper powder and to protect the solid layer 13. A conductive material is appropriately added to the fluororesin-containing urethane resin, and this is applied to a thickness of 5 to 9 μm. It is formed by baking. The resistance value of the coat layer 14 is about 1 × 10 ⁸ Ω.

  Next, a method for manufacturing the rubber roller 10 of the present invention will be described.

  The sponge layer 12 is formed by co-extrusion of the rubber composition of the sponge layer 12 on the outer periphery of a mandrel (metal shaft) having a predetermined diameter and forming it into a crisp shape having a predetermined length. This molded product is put into a steam kettle and foamed and vulcanized (instead of the vulcanization, heating by microwaves may be performed, or press molding (mold molding) using a mold is performed. Also good). Next, the mandrel is extracted and formed into a tube shape, which is cut into a length suitable for the roller dimensions to obtain a foamed sponge tube. This foamed sponge tube is press-fitted into the shaft 11. In this case, the diameter of the mandrel is set so that the inner diameter of the foamed sponge tube is 70 to 90% with respect to the outer diameter of the shaft 11, and when the foamed sponge tube is attached to the shaft 11, the foamed sponge tube is caused by its contraction force. Is retained. This foamed sponge tube is finished and polished to form a sponge layer 12 having a predetermined outer diameter.

  The solid layer 13 is formed by co-extrusion of the rubber composition of the solid layer 13 on the outer periphery of a mandrel (metal shaft) having a predetermined outer diameter, and is formed into a crisp shape having a predetermined length. The molded product is placed in a steam kettle and vulcanized (instead of the vulcanization, heating by microwaves may be performed, or press molding (mold molding) using a mold may be performed) . Next, the mandrel is extracted and formed into a tube shape, which is cut to a length suitable for the roller dimensions to obtain a solid tube.

  FIG. 2 shows a process of manufacturing the rubber roller 10 by inserting the solid tube 13a into the sponge layer 12 inserted into the shaft 11 and polished to a predetermined diameter.

  First, as shown in FIG. 2A, in a state where the sponge layer 12 is press-fitted (inserted) into the shaft 11, the solid tube 13a is set to be fitted. In this state, as shown in FIG. 2 (b), the cap 15 is put on the upper end of the solid tube 13a, and air is injected from the lower end of the solid tube 13a as shown by the arrow in the figure to expand the diameter of the solid tube 13a. While fitting into the sponge layer 12.

  Thereafter, the surface of the solid tube 13a is finish-polished to form the solid layer 13 having an outer diameter of Φ38.2 mm (FIG. 2C). As a result, the sponge layer 12 having a thickness of 4.5 mm is coated on the shaft 11 having an outer diameter of Φ25.4 mm, and the solid layer 13 having a thickness of 1.9 mm, for example, is formed on the sponge layer 12.

  The coat layer 14 is formed by removing rubber residue and dust adhering to the final polishing of the solid layer 13 and then applying a urethane paint to the surface in a thickness of 5 to 9 μm and baking it at a high temperature.

  Thereafter, both ends of the sponge layer 12, the solid layer 13, and the coat layer 14 are cut to form the rubber roller 10 so that the final dimensions are obtained.

  FIG. 3 shows the relationship between the thickness of the solid layer (mm) and the Asker C hardness (°) of the rubber roller.

  In general, the hardness standard of the transfer roller is 35 ° or more and 45 ° or less, and the hardness of the solid layer 13 increases as the thickness of the solid layer 13 increases, and the thickness in the range of the hardness standard of 35 ° or more and 45 ° or less is 0. It becomes the range of 5 mm-2.0 mm.

  However, it was confirmed that wrinkles occurred when the thickness of the solid layer 13 was 0.5 mm and 0.8 mm. Therefore, in this invention, it can be set as the rubber roller which does not generate | occur | produce a wrinkle by making the thickness of the solid layer 13 into 1.0 mm or more.

  Next, Examples 1 to 3 of the present invention will be described based on Tables 1 to 3, and Comparative Examples 1 to 4 will be described based on Table 4.

  In the table, Examples 1 to 3 are manufactured by sponge extrusion → shaft insertion → sponge outer periphery polishing → solid tube coating → solid tube outer periphery polishing → coat layer coating baking, and Comparative Example 1 is sponge extrusion → shaft insertion → sponge outer periphery The polished roller is set in a mold, and a solid layer is manufactured by injecting a solid material into the mold. In Comparative Example 2, a sponge layer and a solid layer are manufactured by simultaneous extrusion. In Examples 3 and 4, after sponge extrusion, shaft insertion, and sponge outer periphery polishing, an adhesive is applied to the outer periphery of the sponge, a solid tube is fitted into the outer periphery of the sponge, and the outer periphery of the solid tube is finished and polished. It is manufactured.

  In Examples 1 to 3, the thicknesses of the sponge layer and the solid layer were changed so that the total thickness of the sponge layer and the solid layer was 5.5 mm. In Comparative Examples 1 to 4, the thickness of the sponge layer was changed to 4. The thickness of 0 mm and the solid layer was 1.5 mm.

  As a result, Comparative Examples 1 and 2 are those in which the sponge layer and the solid layer are integrated by die molding or extrusion, and there are no unevenness of hardness or resistance, but there is unevenness in resistance and resistance. In No. 4, hardness unevenness does not occur, but the resistance value increases and resistance value unevenness occurs.

  On the other hand, Examples 1-3 are favorable with no hardness unevenness, resistance value, and resistance value unevenness.

In Tables 1 to 4, “Hardness” indicates that the hardness of the rubber roller is within the hardness standard of the transfer roller (Asker C hardness is 35 ° or more and 45 ° or less). X was attached to what is. The numbers in parentheses next to ○ or × are values of Asker C hardness (°). In addition, in the item of “hardness unevenness”, the case where the width between the maximum value and the minimum value of the hardness of the rubber roller is less than 4 ° is marked with ○, and the case where it is 4 ° or more is marked with ×. In the item of “resistance value”, the resistance value of the rubber roller is within the resistance value standard of a general transfer roller (1.6 × 10 ⁷ Ω or more and 4.0 × 10 ⁷ Ω or less). A mark that is outside the standard resistance value of the transfer roller is marked with x. In the “resistance value unevenness” item, the ratio between the maximum value and the minimum value of the resistance value of the rubber roller (maximum value / minimum value) is less than 1.2, and the ratio is 1.2 or more. Was attached.

Next, a rubber roller is applied to the actual machine, and a solid layer of twisted paper is used as a general copy paper having a size of A4 size (210 mm × 297 mm) and a thickness (weighing) of 67 g / m ^2. And examined. As a result, in Examples 1-4, 2-4, and 3-4, it was confirmed that the thickness of the solid layer was 1.0 mm and there was no twist of the solid layer. In −5 and 3-5, the solid layer had a thin thickness of 0.8 mm, and kinks occurred. Further, in Examples 1-1, 2-1, and 3-1, the thickness of the solid layer was 2.5 mm and no wrinkle occurred, but the hardness was 50 ° and exceeded the upper limit of 45 ° of the hardness standard. It turned out to be undesirable.

  Accordingly, it was found that the solid layer thickness should be 1.0 mm or more, and the upper limit value of the thickness should be 2.0 mm.

Next, an initial image evaluation was performed by applying a rubber roller to the actual machine. The initial image evaluation was performed using a general copy paper having a size of A4 size (210 mm × 297 mm) and a thickness (basis weight) of 67 g / m ² . As a result, it was good in Examples 1 to 3, but bad in Comparative Examples 1 to 4.

  In addition, in Tables 1 to 4, in the item of “Solid layer scratching”, as a result of checking the solid layer scratching by applying the rubber roller to the actual machine as described above, The confirmed items were marked with an x. In addition, in the item “Evaluation of initial image”, as a result of initial image evaluation (confirmed visually) by applying a rubber roller to the actual machine as described above, the result was “good” and “bad”. X was attached.

10 Rubber roller 11 Shaft 12 Sponge layer 13 Solid layer 14 Coat layer

Claims (6)

In a rubber roller in which at least a sponge layer and a solid layer are sequentially formed concentrically on the shaft,
Shaft is inserted into the sponge layer formed into a tubular shape, said solid layer formed on the tubular to said sponge layer is fitted without using an adhesive, the thickness of the solid layer is, 1.0 mm or more, 2 A rubber roller having a diameter of 0.0 mm or less . The rubber roller according to claim 1 , wherein the sponge layer has a thickness of 3.5 mm or more and 4.5 mm or less. In the method of manufacturing a rubber roller, in which at least a sponge layer and a solid layer are sequentially formed concentrically on the shaft,
The sponge layer is formed into a tube shape by extrusion molding, the solid layer is formed into a tube shape having a thickness of 1.0 mm to 2.0 mm by extrusion molding, and the shaft is press-fitted into the tube-shaped sponge layer A method of manufacturing a rubber roller, wherein the tube-shaped solid layer is fitted into the sponge layer without using an adhesive. After pressing the shaft into the sponge layer, the outer periphery of the sponge layer is polished to a predetermined diameter, and the solid layer is extruded into a tube shape having an inner diameter smaller than the outer diameter of the polished sponge layer. The rubber roller manufacturing method according to claim 3 , wherein the solid layer is expanded in diameter and fitted into the sponge layer. 5. The method of manufacturing a rubber roller according to claim 4 , wherein a value obtained by subtracting the inner diameter of the solid layer from the outer diameter of the sponge layer is greater than 0 mm and equal to or less than 2.0 mm. 6. The method of manufacturing a rubber roller according to claim 4, wherein a coating layer is applied and baked on the outer periphery of the solid layer.

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