Soft tube and manufacturing method thereof, sheet transport roller and manufacturing method thereof

Abstract

To provide a soft tube with an uneven shape on an outer peripheral surface for use as a sheet conveying member, in which uneven scraping during manufacturing is suppressed, and a manufacturing method thereof, and a sheet conveying roller using the soft tube and a manufacturing method thereof.SOLUTION: The soft tube of the present invention is a soft tube used for a sheet conveying portion of the sheet conveying roller, in which the outer peripheral surface includes a region with an uneven shape having a root mean square gradient Sdq in a range of 0.03 to 0.50.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a soft tube and a manufacturing method thereof, and a sheet transport roller and a manufacturing method thereof, and more particularly to a soft tube having an uneven outer surface used as a sheet transport member, in which scraping due to the unevenness during manufacturing is suppressed, and a manufacturing method thereof, and a sheet transport roller using the soft tube and a manufacturing method thereof. [Background technology]

[0002] The sheet transport rollers of multifunction peripherals (MFPs) such as printer multifunction machines are configured by combining a rotatable shaft member and a tubular sheet transport part disposed on the outer periphery of the shaft member. The sheet transport part is made of soft materials with rubber elasticity such as ethylene propylene rubber, urethane rubber, and thermoplastic elastomers so that it can grip and transport sheets such as paper, and the shape is often created by extrusion molding or injection molding.

[0003] However, when such a sheet transport roller is used to transport paper, for example, paper dust generated from the transported paper adheres to the sheet transport section, and when the paper dust comes into contact with the paper again, there are drawbacks such as the sheet transport section slipping and spinning freely, and the paper dust re-adhering to the paper after printing, leaving traces of paper dust.As a method for avoiding these drawbacks, a method is known in which a knurled groove parallel to the length direction of the shaft member is provided on the outer circumferential surface of the sheet transport section by extrusion molding, thereby making it difficult for paper dust to adhere to the sheet transport section (for example, see Patent Document 1).

[0004] The mechanism is to prevent paper dust from adhering to the surface of the sheet conveying section by releasing the paper dust into the recessed portion (groove) during sheet conveyance. However, when knurling grooves are provided on the outer peripheral surface of the sheet conveying section, depending on the shape of the unevenness of the knurling groove, for example, if the unevenness of the knurling groove is far apart, the surface pressure between the sheet conveying section and the sheet may become intermittent, causing uneven gripping and affecting the conveyance of the sheet. In addition, shortening the distance between the unevenness of the knurling groove improves the conveyance of the sheet, but there is a problem that the protruding portion comes into strong contact with the sheet and leaves marks on the sheet.

[0005] To solve these problems, Patent Document 2 proposes a method of suppressing adhesion of paper powder to the sheet conveying section and ensuring sheet conveyance by providing an embossed pattern with a surface roughness Ra of 30 to 80 μm to the outer peripheral surface of a sheet conveying section made of rubber or thermoplastic elastomer with a hardness of 10 to 30° on the Shore A scale. Patent Document 2 uses a molding method using a mold, such as press molding (compression molding) or injection molding, to provide the above-mentioned embossed pattern on the outer peripheral surface of the sheet conveying section.

[0006] However, when a soft tube having an uneven outer surface is molded using the uneven shape of the mold, and then extruded or pulled out in the axial direction (length direction) to release the tube, an undercut occurs, and the unevenness of the mold easily scrapes off the unevenness of the outer surface of the soft tube, which is a problem. In addition, in the case of a rubber elastic body with a low hardness, such as a hardness of 10 to 30° on the Shore A scale, the tackiness increases and the tube sticks strongly to the mold, which makes the unevenness even more likely to be scraped off when the tube is released from the mold.

[0007] Although the number of undercuts will be reduced if the die is configured to be released in the radial direction, the undercuts will remain near the parting, so the problem of uneven wear will not be fundamentally improved. In addition, a step will be created at the parting due to machining errors between the movable die and the fixed die, which will cause new problems such as abnormal noise during sheet transport and damage to the sheet. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 3813480 [Patent Document 2] Patent No. 3707706 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide a soft tube having an uneven shape on its outer peripheral surface used as a sheet transporting member, in which wear due to the unevenness during manufacturing is suppressed, and a manufacturing method thereof, as well as a sheet transporting roller using such a soft tube and a manufacturing method thereof. [Means for solving the problem]

[0010] In the process of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that scraping due to the unevenness during manufacturing can be suppressed by adjusting the uneven shape of the outer peripheral surface of the soft tube so that the root-mean-square slope Sdq is within a range of 0.03 to 0.50, and arrived at the present invention. That is, the above problems according to the present invention are solved by the following means.

[0011] 1. A soft tube used in a sheet transport part of a sheet transport roller, The root mean square slope Sdq on the outer peripheral surface is 0.30 to 0. 44 and the arithmetic mean height Sa of the region having the irregular shape of the outer peripheral surface is within a range of 3.4 to 22.0 μm. The soft tube has a Shore A hardness of 40 to 80 at 25°C. A soft tube characterized by:

[0014] 2 The first method is characterized in that the uneven shape is a random uneven shape. In the section The soft tube described.

[0015] 3 Item 1 is characterized in that there is no parting line on the outer circumferential surface. or paragraph 2 The flexible tube according to claim 1.

[0016] 4 The soft tube is made of a material containing a thermoplastic elastomer. 3 The flexible tube according to any one of claims 1 to 5.

[0017] 5 .Items 1 to 5 4 2. A method for producing a soft tube according to claim 1, wherein the soft tube is molded by injection molding or compression molding.

[0018] 6 A sheet transport roller including a shaft member and a tubular sheet transport portion disposed on an outer peripheral surface of the shaft member, the sheet transport portion being any one of the first to third embodiments. 4 A sheet transport roller comprising the soft tube according to any one of claims 1 to 5.

[0019] 7 The difference between the SP value of the material of the soft tube and the SP value of the material of the shaft member is 1 (cal / cm 3 ) 1 / 2 The second method is characterized in that 6 Item 5. A sheet transport roller according to item 1.

[0020] 8 .No. 6 Section or Article 7 2. A method for manufacturing a sheet transport roller, comprising the steps of: molding the soft tube; inserting the soft tube into a holding portion of a mold having a holding portion for holding the soft tube and a molding portion in which the shaft member is molded so as to contact an inner surface of the soft tube; and molding the shaft member in the molding portion of the mold.

[0021] 9 The method is characterized in that, in the step of forming the shaft member, the inner peripheral surface of the soft tube and the outer peripheral surface of the shaft member are melt-joined. 8 Item 14. A method for producing the sheet transport roller according to item 13. Effect of the Invention

[0022] According to the above-mentioned means of the present invention, it is possible to provide a soft tube having an uneven outer peripheral surface used as a sheet conveying member, in which scraping due to the unevenness during manufacturing is suppressed, a manufacturing method thereof, and a sheet conveying roller using the soft tube and a manufacturing method thereof. The mechanism of manifestation or action of the effect of the present invention is presumed as follows.

[0023] The flexible tube of the present invention has an area on its outer circumferential surface having an uneven shape with a root-mean-square slope Sdq in the range of 0.03 to 0.50. The area having an uneven shape is hereinafter also referred to as an "uneven area". The root-mean-square slope Sdq (hereinafter also simply referred to as "Sdq") is a parameter calculated from the root-mean-square of the slope at all points in a defined area, and is specifically calculated using the following formula (I). Sdq corresponds to a parameter obtained by extending the root-mean-square slope Rdq (defined in JIS B0601) on a roughness curve to a surface, and is a parameter defined in ISO25178.

[0024]

number

[0025] The symbols in formula (I) have the following meanings. A: Area of ​​the measurement range ∂z(x,y) / ∂x: The slope of adjacent points in the X direction ∂z(x,y) / ∂z: The slope of adjacent points in the Y direction

[0026] The inventors have focused on Sdq among various parameters that represent the uneven shape of the outer peripheral surface, and have found that by adjusting Sdq, it is possible to achieve both sheet conveyance performance and suppression of uneven wear during manufacturing. If the Sdq of a soft tube in the uneven region of the outer peripheral surface is 0.03 or more, when this soft tube is used as a sheet conveying roller, it can achieve a sheet conveyance performance at a level that does not cause problems in practical use. If the Sdq of a soft tube in the uneven region of the outer peripheral surface is 0.50 or less, it is possible to suppress uneven wear during manufacturing of the soft tube. [Brief description of the drawings]

[0027] [Figure 1A] FIG. 1 is a perspective view showing an example of an embodiment of a soft tube of the present invention. [Figure 1B] A plan view of the flexible tube shown in FIG. [Figure 1C] A cross-sectional view of the flexible tube shown in FIG. 1A cut along IC-IC in FIG. 1B. [Figure 1D] A cross-sectional view of the flexible tube shown in FIG. 1A cut along the line ID-ID in FIG. 1B. [Diagram 2] FIG. 1 is a perspective view showing an example of an embodiment of a sheet transport roller of the present invention; [Figure 3A] A photograph (18x magnification) of the outer surface of an example of an embodiment of the soft tube of the present invention. [Figure 3B] FIG. 1 is an enlarged cross-sectional view of the vicinity of the outer circumferential surface of an example of an embodiment of a soft tube of the present invention. [Figure 4A] FIG. 1 is a cross-sectional view showing an example of an embodiment of a method for producing a soft tube according to the present invention. [Figure 4B] FIG. 1 is a cross-sectional view showing another example of an embodiment of the method for producing a soft tube of the present invention. [Figure 4C] FIG. 1 is a perspective view illustrating a parting line in a soft tube. [Figure 5A] FIG. 1 is a cross-sectional view of a mold used in an embodiment of a method for manufacturing a sheet transport roller of the present invention. [Figure 5B] FIG. 1 is a cross-sectional view of a sheet conveying roller after a soft tube is inserted into the sheet conveying roller according to an embodiment of the present invention; [Figure 5C]FIG. 1 is a cross-sectional view of a shaft member after a molding step according to an embodiment of a method for manufacturing a sheet transport roller of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The soft tube of the present invention is used in a sheet transport part of a sheet transport roller, and is characterized in that the soft tube has an area on its outer circumferential surface having an uneven shape with a root-mean-square slope Sdq in the range of 0.03 to 0.50. This characteristic is a technical characteristic common to the inventions according to the claims.

[0029] Sdq can be measured, for example, using a three-dimensional white light interference microscope (Wyko (manufactured by Bruker Japan)) as a measuring device. Specifically, for the uneven area, five measurement areas of 2.3 mm × 1.7 mm are randomly selected. For each measurement area, the position coordinates (x, y, z) are measured at 0.5 μm pitch using the measuring device, and the inclination of adjacent points in the X direction and the inclination of adjacent points in the Y direction for each measurement point whose position coordinates have been measured are calculated.

[0030] For each of five randomly selected measurement regions, the values ​​obtained at each measurement point are inserted into formula (I) to calculate Sdq for each measurement region, and the average value of Sdq for the five measurement regions is taken as the Sdq of the uneven region.

[0031] In an embodiment of the soft tube of the present invention, the arithmetic mean height Sa of the region having an uneven shape on the outer circumferential surface is preferably within a range of 3.4 to 50.0 μm. The arithmetic mean height Sa (hereinafter simply referred to as "Sa") is a parameter calculated from the absolute value of the height relative to the average plane at all points in the defined region, and is specifically calculated using the following formula (II). Sa corresponds to a parameter obtained by extending the arithmetic mean height Ra (defined in JIS B0601) on the roughness curve to a surface, and is a parameter defined in ISO25178.

[0032]

number

[0033] The symbols in formula (II) have the following meanings. A: Area of ​​the measurement range |Z(x,y)|: Absolute value of height relative to the mean plane

[0034] For example, the measurement of Sa is performed on the uneven region in the same five measurement regions as the measurement region of Sdq, using the same measuring device as above. First, the position coordinates (x, y, z) are measured at 0.5 μm pitch in the selected measurement region, and the height of the average surface in the measurement region is calculated. Next, the absolute value of the height relative to the average surface at each measurement point where each position coordinate is measured is calculated, and inserted into formula (II) to calculate Sa. Furthermore, the average value of Sa in the five measurement regions is taken as Sa of the uneven region.

[0035] When the Sa of the soft tube in the uneven region of the outer circumferential surface is 3.4 μm or more, the sheet conveyance is good and adhesion of paper powder and the like generated during sheet conveyance to the soft tube can be suppressed. When the Sa of the soft tube in the uneven region of the outer circumferential surface is 50 μm or less, scraping due to the unevenness during manufacturing of the soft tube can be further suppressed.

[0036] As an embodiment of the soft tube of the present invention, from the viewpoint of manifesting the effects of the present invention, it is preferable that the soft tube has a Shore A hardness at 25°C in the range of 40 to 85, and the uneven shape is preferably a random uneven shape. The Shore A hardness can be measured by a method conforming to JIS Z2246. Hereinafter, in this specification, unless otherwise specified, the Shore A hardness refers to the Shore A hardness measured at 25°C by a method conforming to JIS Z2246.

[0037] In terms of the effect of the present invention, it is preferable that the soft tube of the present invention has no parting line on the outer circumferential surface. The parting line refers to a linear step or burr generated along the joint (parting portion) of the mold in the product. Details of the parting line will be described later.

[0038] As an embodiment of the soft tube of the present invention, from the viewpoint of exerting the effects of the present invention, it is preferable that the constituent material of the soft tube contains a thermoplastic elastomer.

[0039] The manufacturing method of the soft tube of the present invention is a manufacturing method of the soft tube of the present invention, characterized in that the soft tube is molded by injection molding or compression molding. Molding by injection molding or compression molding allows for good productivity and low-cost production, and by setting the uneven shape of the outer peripheral surface to Sdq 0.03 to 0.50, the problem of uneven scraping can be suppressed.

[0040] The sheet transport roller of the present invention is a sheet transport roller comprising an axle member and a tubular sheet transport portion arranged on the outer peripheral surface of the axle member, characterized in that the sheet transport portion is the soft tube of the present invention described above.

[0041] In one embodiment of the sheet transport roller of the present invention, from the viewpoint of enhancing the adhesion between the soft tube and the shaft member, the difference between the SP value of the material constituting the soft tube and the SP value of the material constituting the shaft member is 1 (cal / cm 3 ) 1 / 2 It is preferable that the SP value is equal to or less than the above. In this specification, the SP value is a theoretical value calculated by the method by Fedors [Polym. Eng. Sci. 14(2)152, (1974)]. " is a numerical value calculated by the method by Fedors [Polym. Eng. Sci. 14(2)152, (1974)].

[0042] The manufacturing method for a sheet transport roller of the present invention is characterized by comprising the steps of: forming the soft tube; inserting the soft tube into a holding portion of a mold having a holding portion for holding the soft tube and a molding portion in which the shaft member is molded so as to contact the inner surface of the soft tube; and molding the shaft member in the molding portion of the mold.

[0043] In an embodiment of the method for manufacturing a sheet transport roller of the present invention, from the viewpoint of increasing adhesion between the soft tube and the shaft member, it is preferable to melt-join the inner surface of the soft tube and the outer surface of the shaft member in the process of molding the shaft member.

[0044] Hereinafter, the present invention, its components, and the modes and aspects for carrying out the present invention will be described in detail with reference to the drawings. However, the scope of the present invention is not limited to the illustrated examples. The soft tube and the sheet transport roller in the illustrated examples can be appropriately modified without departing from the spirit of the present invention. In this application, the symbol "~" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits.

[0045] [Soft tube] The soft tube of the present invention is a soft tube used in a sheet transport section of a sheet transport roller, and is characterized in that it has a region on its outer circumferential surface having an uneven shape with a root-mean-square slope Sdq in the range of 0.03 to 0.50.

[0046] The flexible tube of the present invention is made of a flexible material. The flexible material is, for example, a material having an elongation (elongation rate) of 100% or more as measured in accordance with JIS K6251. The flexible material preferably has rubber elasticity that causes distortion when stress is applied, but recovers to approximately the original dimensions in a short time when the load is removed.

[0047] FIG. 1A shows a perspective view of a soft tube 1 which is an example of an embodiment of the soft tube of the present invention. FIG. 1B, FIG. 1C, and FIG. 1D show a plan view of the soft tube 1 shown in FIG. 1A, a cross-sectional view of the soft tube 1 cut along IC-IC in the plan view, and a cross-sectional view of the soft tube 1 cut along ID-ID. FIG. 2 is a perspective view showing an example of an embodiment of the sheet transport roller of the present invention. The sheet transport roller 10 shown in FIG. 2 includes a shaft member 2 and a soft tube 1 shown in FIGS. 1A to 1D which is a tubular sheet transport part disposed on the outer peripheral surface S3 of the shaft member 2. FIG. 3A is a photograph (18 times magnification) of the outer peripheral surface of an example of an embodiment of the soft tube of the present invention, and FIG. 3B shows an enlarged cross-sectional view of the vicinity of the outer peripheral surface of an example of an embodiment of the soft tube of the present invention.

[0048] 1A to 1D is a tube body made of a soft material with an inner diameter φ1, an outer diameter φ2, and a length L. The soft tube 1 is used in a sheet transport section of a sheet transport roller. An example of a sheet transport roller in which the soft tube 1 can be used is a sheet transport roller 10 shown in FIG. 2. FIG. 2 also shows a schematic diagram of a mechanism by which the sheet transport roller 10 transports a sheet P.

[0049] The sheet transport roller 10 is a mechanism in which, for example, the shaft member 2 rotates in a circumferential direction, which is the RD direction in Fig. 2, causing the flexible tube 1 to rotate in the same direction, and the sheet P arranged so as to contact the outer peripheral surface S1 of the flexible tube 1 is gripped by the rotation and transported in the PD direction in Fig. 2. Specifically, the sheet P is, for example, sandwiched between the flexible tube 1 of the sheet transport roller 10 and a "roller" (not shown), which is a cylindrical rolling element arranged opposite to and in contact with the flexible tube 1, and is transported by passing between the flexible tube 1 and the roller.

[0050] The outer peripheral surface S1 of the soft tube 1 is a surface that comes into contact with the sheet being conveyed. The outer peripheral surface S1 has an uneven region with an Sdq in the range of 0.03 to 0.50. The uneven region with an Sdq in the range of 0.03 to 0.50 is hereinafter also referred to as the "uneven region A". In the outer peripheral surface S1, the uneven region A preferably exists over the entire circumference with a predetermined width W in the length direction of the soft tube 1. Note that the uneven region A may be composed of a single region with an uneven shape with an Sdq in the range of 0.03 to 0.50, or may be composed of a plurality of regions with different uneven shapes with an Sdq in the range of 0.03 to 0.50, as long as the uneven region A as a whole has an Sdq in the range of 0.03 to 0.50.

[0051] The predetermined width W is not particularly limited as long as it can secure the sheet conveying force. When the outer peripheral surface S1 of the soft tube 1 has an area outside the predetermined width W, the area may be a flat area without irregularities.

[0052] In this specification, the uneven region refers to a region in which an uneven shape is visually recognized when observed under a microscope at 10x magnification.

[0053] In the uneven region A, Sdq is 0.03 to 0.50. If Sdq is within this range, when the soft tube is used as a sheet transport roller, a sheet transportability at a level that does not cause problems in practical use can be realized, and scraping due to unevenness during manufacturing of the soft tube can be suppressed. From the viewpoint of more significantly exhibiting the effects of the present invention, Sdq is preferably within the range of 0.30 to 0.44.

[0054] Sdq is a parameter related to the slope of the unevenness of the uneven shape, and the smaller Sdq is, the gentler the slope of the unevenness is. If Sdq is too small, the interval between the peaks becomes too long, resulting in a decrease in gripping force and uneven gripping. Although the sheet conveying performance depends on the material and shape of the soft tube and the material of the sheet, the soft tube of the present invention can generally obtain a level of sheet conveying performance that does not cause problems in practical use with the following sheets.

[0055] In the present invention, the sheet to be conveyed by the sheet conveying roller can be any sheet used as a recording medium in a multifunction peripheral (MFP) such as a printer multifunction peripheral, without any particular limitation. Examples of the sheet include paper sheets such as coated paper (e.g., art paper, coated paper, lightly coated paper, lightly coated paper, cast paper, etc.) and uncoated paper; plastic sheets made of plastics such as polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, and polybutadiene terephthalate; and sheets made of inorganic materials such as metals and glass.

[0056] The thickness, shape, etc. of the sheet are appropriately selected depending on the application of the image recorded matter obtained by the image forming method of the present invention.

[0057] Regarding uneven wear, although it depends on the hardness of the soft material constituting the soft tube, if Sdq is equal to or less than the above upper limit, undercutting rarely occurs regardless of the type of mold.

[0058] As explained above, Sa in the uneven region A is preferably within the range of 3.4 to 50.0 μm, and more preferably within the range of 3.4 to 22.0 μm.

[0059] Fig. 3A shows a photograph (18x) of the uneven region A on the outer circumferential surface of one example of an embodiment of the soft tube of the present invention. In the uneven region A shown in Fig. 3A, the uneven shape is formed randomly as a grain pattern. In the soft tube of the present invention, the uneven shape in the uneven region A is preferably such a random uneven shape. A random uneven shape makes it possible to more efficiently suppress adhesion of paper powder and the like to the soft tube. Examples of random uneven shapes include leather patterns such as scale patterns, pear-skin patterns, fabric patterns such as wood grain, rock grain, sand grain, cloth grain, and silk grain, and irregular geometric patterns, in addition to grain patterns.

[0060] The above-mentioned uneven shape can be formed, for example, in a molding method using a mold, by molding the soft tube using a mold in which the shape of the molding surface corresponding to the outer peripheral surface of the soft tube is processed to a shape that is plane symmetrical to the outer peripheral surface of the soft tube. In this case, the uneven shape of the region corresponding to the uneven region A on the molding surface of the mold has Sdq of 0.03 to 0.50, and Sdq is preferably 0.30 to 0.44. In addition, the uneven shape of the region corresponding to the uneven region A on the molding surface of the mold has Sa preferably in the range of 3.4 to 50.0 μm, and more preferably in the range of 3.4 to 22.0 μm.

[0061] Here, in the method in which the mold is released in the radial direction as shown in Fig. 4B described later, a parting line PL that extends over the entire length in the longitudinal direction is formed on the outer peripheral surface S1 of the obtained soft tube 1 in correspondence with the joint of the mold (parting part PT) (see Fig. 4C). The presence of a parting line may cause problems such as abnormal noise during sheet conveyance and damage to the sheet, so it is preferable that the soft tube 1 does not have a parting line on the outer peripheral surface S1.

[0062] Also, Fig. 3B shows an enlarged cross-sectional view of the vicinity of the outer circumferential surface of one example of the embodiment of the soft tube of the present invention. The cross-section shown in Fig. 3B is a cross-section of the uneven region A in which uneven shapes are randomly arranged like the grain pattern shown in Fig. 3A, and is, for example, an enlarged view of the vicinity of the outer circumferential surface of the cross-section of the soft tube cut along a plane perpendicular to the length direction shown in Fig. 1C. In the uneven region A in which uneven shapes are randomly arranged like the grain pattern shown in Fig. 3A, a cross-sectional view in which uneven shapes are randomly arranged similarly to that shown in Fig. 3B is obtained in the enlarged view of the vicinity of the outer circumferential surface of the cross-section of the soft tube cut along a plane parallel to the length direction shown in Fig. 1D.

[0063] As described above, the soft material constituting the soft tube 1 is, for example, a material with an elongation (elongation rate) of 100% or more measured in accordance with JIS K6251, and preferably has rubber elasticity that generates distortion when stress is applied but recovers to approximately the original dimensions in a short time when the load is removed. In addition, the soft material constituting the soft tube 1 preferably has a Shore A hardness in the range of 40 to 85, more preferably in the range of 60 to 80.

[0064] By having a Shore A hardness of 40 or more, it is possible to further suppress uneven wear during the manufacturing of the soft tube. Furthermore, it is possible to further suppress adhesion of paper powder and the like generated during sheet transport to the soft tube. By having a Shore A hardness of 85 or less, it is possible to sufficiently ensure sheet transportability.

[0065] The soft material constituting the soft tube 1 may be a conventionally known soft material that mainly contains at least one material selected from rubber and thermoplastic elastomer, which are particularly used in the sheet conveying portion of a sheet conveying roller. The soft material constituting the soft tube may be one of these materials alone or two or more of them may be used in combination. The soft tube 1 preferably contains a thermoplastic elastomer as a constituent material.

[0066] Specific examples of rubber include butyl rubber, butadiene rubber, isoprene rubber, styrene butadiene rubber, chloroprene rubber, natural rubber, 1,2-polybutadiene, acrylonitrile-butadiene rubber, ethylene propylene rubber, acrylic rubber, chlorosulfonated polyethylene, and ethylene-propylene-diene rubber (EPDM).

[0067] Examples of the thermoplastic elastomer include styrene-based elastomers, chlorinated polyethylene, vinyl chloride-based elastomers, olefin-based elastomers, urethane-based elastomers, ester-based elastomers, amide-based elastomers, ionomers, ethylene vinyl acetate (EVA), etc. From the viewpoint of Shore A hardness, styrene-based elastomers, olefin-based elastomers, etc. are preferred.

[0068] As the thermoplastic elastomer, commercially available products can be used. Specifically, examples of styrene-based elastomers include Arneston (registered trademark) CJ series, CE series (manufactured by Kuraray Plastics Co., Ltd.), and Tefablock (registered trademark) (manufactured by Mitsubishi Chemical Corporation). Examples of olefin-based elastomers include Trexplain (trade name) (manufactured by Mitsubishi Chemical Corporation).

[0069] The soft material constituting the soft tube 1 may be prepared by appropriately mixing a thermoplastic elastomer and a resin to produce a soft material having an appropriate hardness. Examples of the resin include the same resins as those used as components of the dynamically crosslinked thermoplastic elastomer described below. The resin is preferably a polyolefin resin, and more preferably polypropylene.

[0070] Furthermore, a dynamically crosslinked thermoplastic elastomer may be used in which a crosslinked rubber component is finely dispersed in a mixed composition of one or more components of a resin and a thermoplastic elastomer. The compounds exemplified above can be used as the thermoplastic elastomer and the rubber component.

[0071] Examples of resins used as components of the dynamically crosslinked thermoplastic elastomer include polyolefin resins such as polyethylene and polypropylene, polyamide resins, polystyrene resins, acrylic resins such as polymethyl methacrylate, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyphenylene sulfide resins, polyphenylene oxide resins, polyphenylene ether resins, acrylonitrile-styrene resins, acrylonitrile-butadiene-styrene resins, polyacetal resins, and fluororesins.

[0072] When used as a sheet conveying portion of a sheet conveying roller, the soft tube 1 is disposed outside the shaft member 2 so that the inner peripheral surface S2 of the soft tube 1 contacts the outer peripheral surface S3 of the shaft member 2, as shown in Fig. 2. In order for the soft tube 1 to rotate together with the shaft member 2, the interface between them, i.e., the outer peripheral surface S3 of the shaft member 2 and the inner peripheral surface S2 of the soft tube 1, is required to be in close contact. The interface is preferably bonded via an adhesive, or the interface is preferably fused and joined by heat fusion or the like.

[0073] In order to obtain a good adhesion state at the interface, it is preferable that the shaft member 2 is made of a material mainly made of resin, and that the outer peripheral surface S3 of the shaft member 2 and the inner peripheral surface S2 of the soft tube 1 are fusion-joined by thermal fusion. Considering the conditions for such fusion-joining, it is preferable that the material constituting the soft tube 1 has an SP value close to that of the material constituting the shaft member 2. Specifically, the difference between the two is 1 (cal / cm 3 ) 1 / 2 It is preferable that the range is within 100 mm.

[0074] 2, two flexible tubes 1 are arranged at intervals with respect to one shaft member 2 such that their outer ends are located approximately the same distance inward from both ends of the shaft member 2. The length of the shaft member 2 is designed, for example, to be longer than the width (length in a direction perpendicular to the conveying direction) of the sheet P to be conveyed, and the two flexible tubes 1 are arranged such that their outer ends are located inward from both ends of the sheet P in the width direction.

[0075] In the sheet conveying roller 10, the number and arrangement positions of the flexible tubes 1 are not limited to those shown in Fig. 2. For example, one flexible tube 1 may be provided on the outer circumferential surface S3 of the shaft member 2 so that both ends of the flexible tube 1 are located inside both ends of the shaft member 2. Also, for example, three or more flexible tubes 1 may be provided on the outer circumferential surface S3 of the shaft member 2 at equal intervals. When multiple flexible tubes 1 are used for one shaft member 2, the inner diameter φ1 and outer diameter φ2 of each flexible tube 1 are the same, but the lengths L may be the same or different.

[0076] Regarding the size of the flexible tube 1, the lower limit of the length L is preferably 10 mm from the viewpoint of ensuring sheet transportability, although it depends on the type (material, size) of the sheet P. The upper limit of the length L of the flexible tube 1 is appropriately selected according to the design of the sheet transport roller 10 as described above. The inner diameter φ1 of the flexible tube 1 is the same as the outer diameter of the shaft member 2, and can be set to be within a range of approximately 4 to 16 mm. The outer diameter φ2 of the flexible tube 1 is determined by the wall thickness T; (φ2-φ1) / 2 and the inner diameter φ1. The wall thickness T of the flexible tube 1 depends on the type of the sheet P and the type of soft material that is the material that constitutes the flexible tube 1, but can be set to be within a range of approximately 1 to 3 mm from the viewpoint of ensuring sheet transportability.

[0077] From the viewpoint of sheet conveyance, it is preferable that the outer diameter φ2 and the wall thickness T of the flexible tube 1 are uniform in the length direction. Furthermore, it is preferable that the wall thickness T is also uniform in the circumferential direction.

[0078] The outer peripheral surface S1 of the soft tube 1 is configured as described above. The inner peripheral surface S2 of the soft tube 1 preferably has a shape that ensures close contact with the outer peripheral surface S3 of the shaft member 2. However, in the case of a manufacturing method in which the soft tube 1 is inserted into a mold, and then the shaft member 2 is molded and melt-joined, the inner peripheral surface S2 of the soft tube 1 comes into contact with the outer peripheral surface S3 of the shaft member 2 and is melt-joined thereto regardless of the shape, ensuring close contact.

[0079] [Soft tube manufacturing method] The manufacturing method of the soft tube of the present invention is not particularly limited as long as the soft tube is manufactured so that the outer peripheral surface has the uneven region A. A manufacturing method using a mold is preferable, and molding by injection molding or compression molding is more preferable, since the effect of suppressing scraping due to unevenness during manufacturing in the present invention is significantly exhibited.

[0080] 4A and 4B are cross-sectional views showing an example of an embodiment of the method for producing a soft tube of the present invention and another example. The example shown in Fig. 4A is an example of a method for producing a soft tube using a mold configured to release the soft tube 1 in the length direction (axial direction). The example shown in Fig. 4B is an example of a method for producing a soft tube using a mold configured to release the soft tube 1 in the radial direction.

[0081] Specifically, FIG. 4A shows an example in which a flexible tube 1 is molded by injection molding using a movable mold 21 consisting of an outer mold 21a and an inner mold 21b, and a fixed mold 23, and then the flexible tube 1 is released from the movable mold 21 in the longitudinal direction.

[0082] 4A, with the movable mold 21 and the fixed mold 23 aligned, a constituent material of the soft tube 1, for example, a thermoplastic elastomer, is injected into the molding portion of the soft tube 1 through an injection port (not shown) that communicates with the molding portion of the soft tube 1 in the movable mold 21. At the time of injection, the thermoplastic elastomer is in a state in which it has been given fluidity by heating.

[0083] The molding surface S of the outer mold 21a has an uneven shape that is plane-symmetrical to the uneven shape of the uneven area A of the outer peripheral surface S1 of the soft tube 1. When injecting the thermoplastic elastomer, the movable mold 21 and the fixed mold 23 are heated to a temperature that does not hinder the flow of the thermoplastic elastomer and is equal to or lower than the temperature at which the thermoplastic elastomer solidifies. The heating temperature of the thermoplastic elastomer and the mold depends on the type of thermoplastic elastomer. The injection speed and pressure are adjusted appropriately. For example, the injection speed is preferably 2 to 5 mm / sec, and the pressure is preferably maintained at 10 to 30 MPa. The retention time is preferably about 2 to 5 seconds.

[0084] Thereafter, the movable die 21 and the fixed die 23 are cooled to near room temperature, and after the shape of the soft tube 1 is fixed, the movable die 21 and the fixed die 23 are separated. The cooling time is preferably 20 seconds or more. This state is shown in FIG. 4A. In FIG. 4A, reference numeral 22 denotes an ejector pin. The soft tube 1 is released from the mold by pushing out the ejector pin 22 in the length direction (axial direction) of the soft tube 1 as shown by the arrow. The ejector pin is preferably pushed out at a speed of 1 to 5 mm / sec, and more preferably 1.5 to 4 mm / sec.

[0085] Here, before demolding, the outer mold 21a and the soft tube 1 are in a fitted state between the molding surface S side of the outer mold 21a and the outer peripheral surface S1 side of the soft tube 1. However, in the uneven area A of the outer peripheral surface S1 of the soft tube 1, since Sdq is within the above range, the uneven shape is easily elastically deformed during demolding, so that an undercut does not occur and the occurrence of scraping of the unevenness can be suppressed.

[0086] FIG. 4B shows an example in which a flexible tube 1 is molded by injection molding using a movable mold 24, a fixed mold 25, and an inner mold 26, and then the flexible tube 1 is radially released from the movable mold 24.

[0087] 4B, with the movable mold 24, the fixed mold 25, and the inner mold 26 aligned, a constituent material of the soft tube 1, for example, a thermoplastic elastomer, is injected into the molding portion of the soft tube 1 through an injection port (not shown) communicating with the molding portion of the soft tube 1. At the time of injection, the thermoplastic elastomer is in a state in which it has been given fluidity by heating.

[0088] The molding surfaces S of the movable mold 24 and the fixed mold 25 have an uneven shape that is plane-symmetrical to the uneven shape of the uneven area A of the outer peripheral surface S1 of the soft tube 1. When injecting the thermoplastic elastomer, the movable mold 21 and the fixed mold 23 are heated to a temperature that does not hinder the flow of the thermoplastic elastomer and is equal to or lower than the temperature at which the thermoplastic elastomer solidifies. The heating temperature of the thermoplastic elastomer and the mold depends on the type of thermoplastic elastomer. The injection speed and pressure are adjusted appropriately. For example, the injection speed is preferably 2 to 5 mm / sec, and the pressure is preferably maintained at 10 to 30 MPa. The retention time is preferably about 2 to 5 seconds.

[0089] Thereafter, the movable mold 24, the fixed mold 25, and the inner mold 26 are cooled to near room temperature, and the shape of the soft tube 1 is fixed, and then the movable mold 24 and the fixed mold 25 are separated. The cooling time is adjusted appropriately. The cooling time is preferably 20 seconds or more. This state is the state shown in FIG. 4B. Note that before separation, the fixed mold 25 and the soft tube 1 are in a fitted state at the molding surface S side of the fixed mold 25 and the outer peripheral surface S1 side of the soft tube 1, but in the uneven region A of the outer peripheral surface S1 of the soft tube 1, since Sdq is within the above range, the uneven shape is easily elastically deformed when the molds are separated, so that an undercut state does not occur, and the occurrence of uneven chipping can be suppressed.

[0090] 4B, reference numeral 22 denotes an ejector pin. The ejector pin 22 is pushed out in the radial direction of the soft tube 1 as indicated by the arrow, thereby releasing the soft tube 1 from the mold. The ejector pin is preferably pushed out at a speed of 1 to 5 mm / sec.

[0091] The inner mold 26 is pulled out from the soft tube 1 by, for example, a slide core method. Before demolding, the movable mold 24 and the soft tube 1 are in a fitted state at the molding surface S side of the movable mold 24 and the outer peripheral surface S1 side of the soft tube 1, but in the uneven region A of the outer peripheral surface S1 of the soft tube 1, since Sdq is within the above range, the uneven shape is easily elastically deformed during demolding, so that an undercut does not occur and the occurrence of chipping of the unevenness can be suppressed.

[0092] Here, as shown in FIG. 4B, it is inevitable that the parting portion PT of the movable side mold 24 and the fixed side mold 25 will be misaligned due to processing errors. Due to this misalignment, a step D is formed in the outer peripheral surface S1 of the soft tube 1 at a location corresponding to the parting portion PT. The step D is formed in a line shape along the entire length of the outer peripheral surface S1 of the soft tube 1 in the length direction along the two parting portions PT of the movable side mold 24 and the fixed side mold 25, and becomes a parting line. FIG. 4C shows a perspective view of the soft tube 1 having the parting line PL formed in this way. Although not shown in FIG. 4C, this soft tube 1 has another parting line PL on the back surface similar to the one shown in the figure.

[0093] It is preferable that the soft tube 1 does not have a parting line PL. Therefore, in the present invention, it is preferable that the soft tube 1 is molded using a mold configured to release the soft tube 1 in the length direction (axial direction).

[0094] [Sheet transport roller] The sheet transport roller of the present invention is a sheet transport roller comprising an axle member and a tubular sheet transport portion arranged on the outer peripheral surface of the axle member, characterized in that the sheet transport portion is the soft tube of the present invention described above.

[0095] The sheet transport roller of the present invention includes a shaft member and a sheet transport section as essential members. Using the sheet transport roller 10 shown in Fig. 2 as an example, the soft tube 1, which is one of the essential members of the sheet transport roller 10, has been described above. Below, the shaft member 2, which is another essential member of the sheet transport roller 10, will be described.

[0096] As described above, the outer peripheral surface S3 of the shaft member 2 is in close contact with the inner peripheral surface S2 of the soft tube 1. As a result, when the shaft member 2 is rotated in the circumferential direction, the soft tube 1 also rotates in the circumferential direction at the same time. The shaft member 2 is configured to support and rotate the soft tube 1, thereby enabling the sheet P to be conveyed as described above.

[0097] The material constituting the shaft member 2 is not particularly limited as long as it can perform the above-mentioned functions. Specifically, various metals and resins having appropriate rigidity can be used. Specifically, the bending modulus of elasticity according to JIS K7171 is about 1200 (N / mm 2 In addition, in consideration of the adhesion with the soft tube 1, the material constituting the shaft member 2 is preferably a resin.

[0098] It is preferable that the shaft member 2 is fusion-bonded to the soft tube 1 by heat fusion or the like. In order to improve the bonding property in the fusion bonding, as described above, it is preferable that the SP value of the soft material constituting the soft tube 1 is close to the SP value of the material constituting the shaft member 2. Specifically, the difference between the two is 1 (cal / cm 3 ) 1 / 2 It is preferable that the range is within 100 mm.

[0099] From the viewpoint of the above SP value, the same resin as the resin used as a component of the dynamically crosslinked thermoplastic elastomer can be used as the material for the shaft member 2. As the material for the shaft member 2, a material having an SP value that satisfies the above condition may be appropriately selected according to the SP value of the material for the soft tube 1.

[0100] Specifically, resins preferably used as materials for forming the shaft member 2 include polyolefin resins such as polypropylene, polyacetal resins, polycarbonate resins, etc., and polypropylene is more preferable from the viewpoints of environment and cost. In this specification, the term "polypropylene" refers to a (co)polymer using propylene as a main component as a raw material monomer, for example, at 50 mol % or more. Other resins are defined similarly.

[0101] The resin may be a commercially available product. Specific examples of polypropylene include PP-R200 (manufactured by Kinpatsu Kagaku Co., Ltd.) and various grades of Novatec (registered trademark) PP, such as BC3AD (manufactured by Japan Polypropylene Corporation).

[0102] The shape of the shaft member 2 is preferably cylindrical. Note that, as long as the portion of the shaft member 2 having the soft tube 1 on the outer circumferential surface S3 is cylindrical, the other portions do not necessarily have to be cylindrical. The shape of a cross section taken along a plane perpendicular to the longitudinal direction of the shaft member 2 in the portion not having the soft tube 1 may be a polygon, a star, a circle with a diameter different from that of the portion having the soft tube 1, or the like, as necessary.

[0103] Regarding the size of the shaft member 2, at least the portion where the shaft member 2 has the soft tube 1 has an outer diameter that is the same as the inner diameter φ1 of the soft tube 1, and can be within a range of approximately 4 to 16 mm. The outer diameter of the shaft member 2 can be, for example, approximately 4 to 16 mm over its entire length. The length of the shaft member 2 is appropriately adjusted depending on the size of the sheet to be conveyed.

[0104] When the shaft member 2 is made of resin, it can be molded by, for example, extrusion molding, injection molding, compression molding, etc. In the manufacturing method of the sheet conveying roller of the present invention described later, injection molding is used.

[0105] The sheet transport roller 10 is used, for example, by being installed in a paper feed section of a printer / multifunction device. In the paper feed section, both ends of the shaft member 2 are attached to bearings, and at least one end is connected to a drive section. In the paper feed section, a cylindrical roller is disposed facing the soft tube 1, which is the sheet transport section, and is pressed against the soft tube 1 to the extent that the sheet (paper) can be transported. The soft tube 1 and the roller are disposed so that their length directions (axial directions) are parallel to each other. The sheet (paper) is clamped by the soft tube 1 in the gap. The sheet (paper) is transported together with the rotation of the soft tube 1, which rotates in accordance with the rotation of the shaft member 2 in the circumferential direction.

[0106] [Method of manufacturing sheet transport roller] The sheet transport roller of the present invention can be manufactured, for example, by disposing a soft tube at a predetermined position in the longitudinal direction of the shaft member such that the outer peripheral surface of the shaft member and the inner peripheral surface of the soft tube are in close contact with each other. The outer peripheral surface of the shaft member and the inner peripheral surface of the soft tube may be bonded to each other by, for example, an adhesive or the like, or may be fused and joined by, for example, heat fusion. The sheet transport roller of the present invention is preferably manufactured by the manufacturing method of the present invention described below.

[0107] The method for producing the sheet transport roller of the present invention is a method for producing the sheet transport roller of the present invention, and is characterized by having the following steps (1) to (3).

[0108] (1) A step of molding the soft tube of the present invention (2) A step of inserting a soft tube into a holding portion of a mold having a holding portion for holding the soft tube and a molding portion in which an axial member is molded so as to contact an inner peripheral surface of the soft tube. (3) forming the shaft member in a forming portion of the die;

[0109] The above-described manufacturing method for the flexible tube of the present invention can be applied to the above-described step (1). Steps (2) and (3) will be described below with reference to the drawings.

[0110] Figures 5A, 5B, and 5C show a cross-sectional view of a mold 30 used in one embodiment of the manufacturing method for a sheet transport roller of the present invention, a cross-sectional view of the mold 30 with a soft tube 1 inserted after step (2), and a cross-sectional view of the mold 30 including the soft tube 1 and the shaft member 2 after step (3).

[0111] The mold used in the manufacturing method of the present invention will be described using the mold 30 shown in Fig. 5A as an example, but the mold is not limited to this. The mold 30 shown in Fig. 5A is composed of a first mold 31 and a second mold 32 that can be separated in the X direction at a parting part PT or the like.

[0112] The mold 30 has a holding section 41 that holds the flexible tube 1 when the first mold 31 and the second mold 32 are joined together, and a molding section 42 in which the shaft member 2 is molded so as to contact the inner circumferential surface S2 of the flexible tube 1 held by the holding section 41. The mold 30 further has a resin injection path 43 that communicates from the molding section 42 to the outside of the mold 30. The mold 30 has the holding sections 41 in two locations, and can be used, for example, as a mold for molding the sheet transport roller 10 shown in FIG. 2. In this case, the holding sections 41 that hold the flexible tube 1 are provided in two locations corresponding to the positions at which the flexible tube 1 is disposed on the sheet transport roller 10.

[0113] The resin injection path 43 is provided so that the resin, which is the constituent material of the shaft member 2, can be injected from an opening portion communicating with the outside of the mold 30 and reach the molding portion .

[0114] In the step (2), for example, in a state where only the first mold 31 is separated from the mold 30, the soft tube 1 is inserted into the two holding parts 41. The holding parts 41 are formed to have the same size and shape as the outer peripheral shape of the soft tube 1 so that the soft tube 1 does not move in the step (3). It is necessary to maintain the uneven shape in the uneven area A of the outer peripheral surface S1 of the soft tube 1 even after the step (3). However, in the step (3), since the uneven shape can be maintained without providing the holding part 41 with an uneven shape equivalent to that of the outer peripheral surface S1 of the soft tube 1, it is not necessary to provide a special shape to the surface of the holding part 41. After the soft tube 1 is inserted, the first mold 31 is joined to the second mold 32 at the parting part PT to be in a state shown in cross section in FIG. 5B.

[0115] In the step (3), the resin, which is the material constituting the shaft member 2, is injected from the opening of the resin injection passage 43 and transferred to the molding section 42, filling the molding section 42 with the resin. At this time, the resin is made fluid by heating. When injecting the resin, the first mold 30 and the second mold 31 are heated to a temperature that does not hinder the flow of the resin and is below the temperature at which the resin solidifies. The heating temperature of the resin and the mold depends on the type of resin. The injection speed and pressure are adjusted appropriately. For example, the injection speed is preferably 30 to 70 mm / sec, and the pressure is preferably maintained at 50 to 70 MPa. The retention time is preferably about 5 to 20 seconds.

[0116] In the step (3), the inner circumferential surface S2 of the soft tube 1 and the outer circumferential surface S3 of the shaft member 2 can be melt-joined by adjusting the temperatures of the resin and the mold. In the manufacturing method of the present invention, it is preferable to adjust the temperatures of the resin and the mold to a temperature at which the melt-joining can be achieved. However, the temperatures of the resin and the mold are set to a temperature at which the uneven shape in the uneven area A of the outer circumferential surface S1 of the soft tube 1 can be maintained.

[0117] In the step (3), the metal mold 30 having the molded product therein is cooled to a temperature equal to or lower than the solidification temperature of the resin, and after the shape of the molded product is fixed, the first metal mold 31 and the second metal mold 32 are separated. The cooling time is adjusted appropriately. The cooling time is preferably 20 seconds or more. As shown in FIG. 5C, the molded product has two soft tubes 1 for one shaft member 2, for example, the sheet conveying roller 10 shown in FIG. 2, to which a resin member 2X molded in the shape of the resin injection path 43 is attached. After the molded product is released from the metal mold 30, the resin member 2X is cut to obtain the sheet conveying roller 10. EXAMPLES

[0118] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.

[0119] [Manufacture of soft tubes] Using the styrene thermoplastic elastomers shown in Table I below as the thermoplastic elastomers, flexible tubes 1 to 11 were produced under the following conditions.

[0120] [Table 1]

[0121] The soft tube was injection molded using a mold so that it had a cylindrical shape and had an outer diameter of 16 mm, an inner diameter of 12 mm, and a length of 10 mm.

[0122] The molds used were molds A to G, which have a configuration for releasing a soft tube in the length direction similar to that shown in FIG. 4A and have molding surfaces S with different shapes. Using the molds and thermoplastic elastomers shown in Table II, soft tubes 1 to 11 were manufactured under the following molding conditions 1 to 3. Molding condition 1 was thermoplastic elastomer temperature: 210°C, mold temperature: 40°C, injection speed: 5 mm / sec, cooling time: 35 seconds, holding pressure: 15 MPa, and ejector pin extrusion speed: 1.5 mm / sec. Molding condition 2 and molding condition 3 were the same as molding condition 1, except that the ejector pin extrusion speeds were 3.0 mm / sec and 4.5 mm / sec, respectively. The soft tubes in Table II are described below. 3, 5 ,6, 7 and 11 The word "present invention" in the remarks column should be read as "reference example."

[0123] <Measurement of outer peripheral surface unevenness> The uneven shape of the outer peripheral surface of the soft tube was measured by measuring the uneven shapes of the molding surfaces of the molds A to G used in producing the soft tube. Each of had a random uneven shape overall.

[0124] Specifically, the uneven shapes Sa and Sdq on the molding surfaces of the molds A to G were measured by measuring the uneven shapes of flat plates processed under the same conditions as the molding surfaces of the molds A to G. Five measurement areas of 2.3 mm x 1.7 mm were randomly selected. Using a three-dimensional white light interference microscope (Wyko (manufactured by Bruker Japan)), Sdq and Sa in each measurement area were measured by the method described above, and the average values ​​of Sdq and Sa in the five measurement areas were calculated. The results are shown in Table II.

[0125] Here, for the soft tubes 1 and 2, which are comparative examples, the occurrence of uneven scraping was confirmed in the following evaluation. Therefore, Sdq and Sa described in the uneven shape column of Table II are Sdq and Sa of the molding surface of the mold, and do not reflect the uneven shape of the outer peripheral surface of the soft tubes 1 and 2. For the soft tubes 3 to 11, which are examples of the present invention, Sdq and Sa described in the uneven shape column of Table II are Sdq and Sa of the molding surface of the mold, and are also Sdq and Sa of the outer peripheral surface of the soft tubes 3 to 11.

[0126] <Evaluation of uneven scraping> In the soft tubes 1 to 11, the uneven wear during manufacturing was evaluated according to the following criteria. The uneven wear was judged visually, and a case where the unevenness of the outer peripheral surface was worn even slightly was rated as "irregular wear". The results are shown in Table II.

[0127] (Evaluation Criteria) ◯: No uneven chipping occurred under all molding conditions 1 to 3. △: Uneven wear occurred only under molding condition 3. In other words, uneven wear can be suppressed depending on the molding conditions. ×: Uneven scraping occurred under all molding conditions 1 to 3.

[0128] [Manufacturing of sheet transport rollers] The material of the shaft was polypropylene (PP-R200 (Kinpachi Kagaku Co., Ltd.), SP value = 8.1 (cal / cm 3 ) 1 / 2 ) and a mold similar to that shown in FIG. 5A were used to manufacture a sheet conveying roller having two soft tubes for one shaft member having a configuration similar to that shown in FIG. 2 by injection molding according to the manufacturing method of the present invention.

[0129] The soft tubes used were the soft tubes 1 to 11 obtained under the above molding condition 1, and the sheet transport rollers 1 to 11 were manufactured using these soft tubes 1 to 11. The outer diameter of the shaft member was 12 mm, and the length was 220 mm.

[0130] Specifically, for the sheet transport roller 1, the mold was separated and two soft tubes 1 were inserted into the two holding parts, and then the three parts of the mold were joined at the parting parts to form the state shown in FIG. 5B. Then, the polypropylene, which is the material of the shaft member 2, was injected from the opening of the resin injection path 43 and transferred to the molding part 42, and the molding part 42 was filled with the polypropylene to form the shaft member. The molding conditions were resin temperature: 210°C, mold temperature: 50°C, injection speed: 70 mm / sec, cooling time: 50 sec, and dwell pressure: 50 MPa. After molding, the molded product was released from the mold and unnecessary parts were cut off to obtain the sheet transport roller 1.

[0131] Sheet transport rollers 2 to 11 were produced in the same manner, except that the flexible tube 1 was replaced with the flexible tubes 2 to 11.

[0132] <Evaluation of Paper Dust Adhesion> The sheet transport rollers 1 to 11 obtained above were attached to the paper feed section of a printer multifunction machine (manufactured by Konica Minolta), and paper (Konica Minolta CF Paper A4) was transported 100 times to cause paper dust to adhere to the soft tube. Then, five sheets of paper (Konica Minolta CF Paper A4) printed so that the entire paper was filled with process blue (cyan + magenta) were transported, and it was confirmed whether the paper dust would re-adhere to the paper. The state of paper dust adhesion was visually confirmed and evaluated according to the following criteria. The results are shown in Table II.

[0133] (Evaluation Criteria) A: No paper dust adhesion at all, at a level that can be used for rollers that are susceptible to paper dust adhesion. b: Paper powder adheres, but this is at a level that can be used for rollers that are not easily affected by paper powder adhesion.

[0134] <Paper transportability evaluation> The sheet transport rollers 1 to 11 obtained above were each attached to the paper feed section of a printer multifunction machine (Konica Minolta), and a piece of paper (Konica Minolta CF paper cut to a width of 2 cm and a length of 29.7 cm) was sandwiched between the soft tube and the roller so that the width direction coincided with the length direction (axial direction) of the soft tube, and the pull-out force when pulling the piece of paper in the length direction was measured with a push-pull gauge. The paper transport property was evaluated according to the following criteria from the measured pull-out force. The results are shown in Table II.

[0135] (Evaluation Criteria) ◯: The pulling force is 2.5 N or more and the paper transport force is sufficient. △: The pulling force is 2.0 N or more and less than 2.5 N, and the paper transport force is within the standard. ×: The pulling force is less than 2.0 N, and the paper conveying force is insufficient.

[0136] [Table 2]

[0137] From Table II, it can be seen that in the soft tube of the present invention, scraping due to unevenness during manufacturing is suppressed. Also, in a preferred embodiment, adhesion of paper powder is suppressed, and there is no problem with paper conveyance. [Explanation of symbols]

[0138] 1 Soft tube 2 Shaft member 10 Sheet transport roller

Claims

1. A soft tube used in a sheet conveying portion of a sheet conveying roller, A soft tube, characterized in that the soft tube has an area on its outer peripheral surface having an uneven shape with a root mean square slope Sdq in the range of 0.30 to 0.44, and the arithmetic mean height Sa of the area on the outer peripheral surface having an uneven shape is in the range of 3.4 to 22.0 μm, and the Shore A hardness of the soft tube at 25° C. is in the range of 40 to 80.

2. 2. The flexible tube according to claim 1, wherein the uneven shape is a random uneven shape.

3. 3. The flexible tube according to claim 1, wherein no parting line is present on the outer circumferential surface.

4. The flexible tube according to any one of claims 1 to 3, characterized in that a constituent material of the flexible tube contains a thermoplastic elastomer.

5. A method for producing the soft tube according to any one of claims 1 to 4, comprising the steps of: A method for producing a soft tube, comprising molding the tube by injection molding or compression molding.

6. A sheet conveying roller including a shaft member and a tubular sheet conveying portion disposed on an outer circumferential surface of the shaft member, A sheet transport roller, wherein the sheet transport portion is the soft tube according to any one of claims 1 to 4.

7. The difference between the SP value of the material constituting the soft tube and the SP value of the material constituting the shaft member is 1 (cal / cm ３ ) １／２ 7. The sheet transport roller according to claim 6, wherein:

8. A method for manufacturing the sheet transport roller according to claim 6 or 7, comprising the steps of: forming the soft tube; a step of inserting the soft tube into a holding portion of a mold having a holding portion for holding the soft tube and a molding portion in which the shaft member is molded so as to contact an inner peripheral surface of the soft tube; molding the shaft member in a molding portion of the die; A method for manufacturing a sheet transport roller comprising the steps of:

9. 9. The method for manufacturing a sheet conveying roller according to claim 8, wherein in the step of forming the shaft member, an inner peripheral surface of the soft tube and an outer peripheral surface of the shaft member are melt-joined.

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