JPH0573924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a conductive roller suitably used as a toner conveying roller or paper feeding roller of an electrophotographic copying machine, and a method for manufacturing the same.

(Prior art) Conventionally, conductive rollers used for the above-mentioned purposes include a metal core having a rotating shaft, a soft foam layer made of a porous polymeric material such as rubber or resin on the outer surface, and a non-porous layer on the outer surface. A structure is known in which a hard skin layer made of a flexible polymeric material is provided, and not only the hard skin layer but also a soft foam layer is provided with conductivity.

The reason why such a conductive roller has a composite structure consisting of a soft foam layer and a hard skin layer on the outer surface of the core metal is that it is generally used by pressing against and rotating a mating roller with high rigidity or a sheet-like conveyed object such as paper. This is to prevent deformation of the core metal of the mating roller or the roller itself and deterioration of functions such as toner transport or paper feeding in the developing section of an electrophotographic copying machine. This is intended to provide mechanical strength and to ensure a predetermined pressure contact area on the roller surface and a predetermined frictional force due to the easy compressive deformability of the inner soft foam layer.

In addition, in such conductive rollers, the conductivity of the hard skin layer is imparted by incorporating a large amount of conductive substance (acetylene black, metal powder, etc.) into the polymeric material, while the conductivity of the soft foam layer is When a foamable polymer material contains a conductive substance such as the one described above and is foamed, the cells formed by the foaming are destroyed by the conductive substance, etc., and uniform cells are not formed, resulting in mechanical damage. Because of the problem of poor strength and inability to obtain good compressive deformability, it is usually applied by forming a soft foam layer and then impregnating the foam layer with a conductive paint.

(Problems to be Solved by the Invention) However, in a conductive roller having a soft foam layer impregnated with a conductive paint as described above, the foam layer becomes hard and brittle, and the original function of the foam layer is not performed. Compressive deformability or cushioning properties under a certain low load are impaired, resulting in poor mechanical strength and reduced durability.

The present invention was invented based on the above circumstances, and an object of the present invention is to provide a highly durable conductive roller that eliminates the above-mentioned conventional problems and takes advantage of the inherent characteristics of the foam layer, and a method for manufacturing the same. This is the purpose.

(Solution Means) In order to achieve the above object, the conductive roller of the present invention has a special structure in which conductive fibers are placed between the core bar and the hard skin layer in order to form conductive conductivity between the two. One end was fixed to the outer surface of the core metal, and the other fiber portions of the conductive fibers except for the vicinity of the fixed end were arranged in a helical manner in contact with the inner surface of the hard skin layer in the axial direction.

Further, in the method for manufacturing a conductive roller of the present invention, while forming a hard skin layer made of a non-porous polymeric material that has been given conductivity in advance, one end of the conductive fiber is fixed to the outer surface of the core metal, and then After that, the hard skin layer is placed in a predetermined mold, and the core metal is inserted and arranged concentrically inside the hard skin layer, and then the core metal is rotated in the circumferential direction to remove the conductive fibers from the conductive fibers. The other fiber parts except for the vicinity of the fixed end are arranged in a helical manner in contact with the inner surface of the hard skin layer in the axial direction, and then a foamable polymeric material is cast between the core metal and the hard skin layer, It is characterized by foaming and forming a soft foam layer.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings based on the example.

FIG. 1 shows an embodiment of the conductive roller of the present invention, in which a soft foam layer 2 made of a polymeric material such as porous rubber or resin is provided on the outer surface of a metal core 1.
Furthermore, a hard skin layer 3 made of non-porous rubber or resin polymer material is provided on the outer surface. Furthermore, conductive fibers 4 are connected and arranged between the outer surface 1a of the core metal and the inner surface 3a of the hard skin layer. This conductive fiber 4 has one end fixed to the outer surface 1a of the core bar,
The fiber portions other than those near the fixed end are arranged in a helical manner in contact with the hard skin layer inner surface 3a in the axial direction.

The soft foam layer 2 is made of a polymer material such as rubber or resin (thermoplastic resin such as urethane or vinyl chloride) containing a foaming agent, etc., and has a density of 0.05 to 0.8 g/cm ³ , preferably 0.1 to 0.5 g/cm ³ Constructed as a soft foam. The density greatly affects the compressive deformability and cushioning properties of the roller, and can be adjusted as appropriate by changing the amount of material input into the mold or the amount of foaming agent added. The material constituting the soft foam layer 2 is preferably a material that can be cast in liquid form, such as liquid urethane, from the viewpoint of processability.

The hard skin layer 3 is made of a polymeric material such as rubber or resin such as ethylene propylene diene rubber, chloroprene rubber, urethane rubber, silicone rubber, etc., and has a hardness of 50 to 80 (JIS-A hardness). ) is hard and has uniform conductivity throughout (volume resistivity of about 1×10 ⁶ to 1×10 ^-2 Ω-cm). In addition, in the present invention, depending on the application, the hard skin layer may be formed with a plurality of protrusions (the shape of the protrusions is:
The radial cross section may be rectangular, trapezoidal, semicircular, etc.).

In addition, the conductive fiber 4 is made of carbon fiber, metal fiber, or metal wire, which has excellent strength, in order to prevent the flexibility of the roller and the tensile force acting on the roller during repeated compression use to prevent breakage, etc. etc., and at least one or more conductive fibers are disposed in contact with the inner surface 3a of the hard skin layer in a spiral shape for one or more turns.

Next, a method for manufacturing a conductive roller according to the present invention will be explained.

The purpose of the manufacturing method of the present invention is to create a gap between the core metal 1 and the hard skin layer 3 without subjecting the foam layer to any treatment such as impregnating it with conductive paint in order to take advantage of the inherent characteristics of the soft foam layer. Therefore, while forming the cylindrical hard skin layer 3 in advance, one end of the conductive fiber 4 is fixed to the end of the outer surface 1a of the core metal by gluing or wrapping, and then, The hard skin layer 3 is placed in a predetermined mold, and the core metal 1 is inserted concentrically inside the hard skin layer 3 from the side to which the conductive fibers 4 are fixed, and then the core metal 1 is inserted. By rotating in the circumferential direction, the conductive fibers 4 are brought into sliding contact with the hard skin layer inner surface 3a in an axial direction in a helical manner, and then a liquid cast-moldable material is cast and foamed to form the soft foam layer 2. At the same time, the conductive fibers 4 are fixedly arranged between the outer surface 1a of the core metal and the inner surface 3a of the hard skin layer.
In this way, only one end of the conductive fiber 4 is fixed to the outer surface 1a of the core metal, without using any adhesive method, and without performing any conductive treatment on the soft foam layer 2 itself. , easily and the outer surface 1a of the core metal
This makes it possible to conduct electricity between the hard skin layer inner surface 3a and the hard skin layer inner surface 3a.

Note that if the soft foam layer 2 is thin, a groove or the like may be provided on the outer surface 1a of the core metal, and one end of the conductive fiber 4 may be fixed in the groove using a conductive adhesive or the like. can. In addition, the material and length of the conductive fiber 4,
By selecting the diameter, the number of helical turns, the pitch, etc., the bending elastic force applied to the inner surface 3a of the hard skin layer 3 can be adjusted, and the hard skin layer 3 can be manufactured without causing wrinkles or other undulations. It does not cause large stress.

(Effects of the Invention) As explained above, the conductive roller of the present invention has
Since the conductive fibers are arranged in a special structure between the outer surface of the core metal and the hard skin layer, good conductivity can be achieved easily and reliably without applying any conductivity treatment to the soft foam layer itself. can be obtained. Therefore, according to the roller of the present invention having a composite structure having a hard skin layer and a soft foam layer, the hard skin layer imparts a predetermined rigidity to the roller surface layer, and the inner soft foam layer has a predetermined rigidity. As a result, the original functions of the foam layer, such as compressive deformability and cushioning properties, are reliably exhibited, and while it has excellent electrical conductivity, it is also far more durable than conventional foam layers. It will be excellent.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an embodiment of the conductive roller of the present invention. 1... Core metal, 1a... Core metal outer surface, 2... Soft foam layer,
3... Hard skin layer, 3a... Hard skin layer inner surface, 4... Conductive fiber.

Claims (1)

[Scope of Claims] 1 A metal core and a cylindrical hard skin layer made of a non-porous polymeric material imparted with conductivity and arranged concentrically on the outside of the core, having porous In addition to disposing a soft foam layer made of a flexible polymer material, the outer surface of the core metal and the inner surface of the hard skin layer are connected with conductive fibers.
In a conductive roller in which a core metal and a hard skin layer are formed to be electrically conductive, one end of the conductive fiber is fixed to the outer surface of the core metal, and other fiber portions of the conductive fiber except for the vicinity of the fixed end are fixed to the outer surface of the core metal. A conductive roller characterized in that it is arranged in a helical shape in contact with the inner surface of a hard skin layer in the axial direction. 2. While forming a hard skin layer made of a non-porous polymer material that has been given conductivity in advance, one end of the conductive fiber is fixed to the outer surface of the core metal, and then the hard skin layer is placed in a predetermined mold. At the same time, the core metal is coaxially inserted and arranged inside the hard skin layer, and then the core metal is rotated in the circumferential direction, so that the other fiber portions of the conductive fibers except for the vicinity of the fixed end are inserted into the hard skin layer. The layer is arranged so that it is in spiral contact with the inner surface of the layer in the axial direction, and then a foamable polymeric material is cast between the core metal and the hard skin layer and foamed to form a soft foam layer. A method for manufacturing a conductive roller.