JP2018203530A - Paper feeding roller and image forming device - Google Patents

Abstract

To provide a paper feeding roller capable of maintaining excellent paper feed performance by suppressing increase of the number of paper powder pressure-bonded to an outer peripheral surface of a roller body and deterioration of friction coefficient of the outer peripheral surface even when paper feeding is repeated over a long period, and an image forming device incorporating the paper feeding roller.SOLUTION: In a paper feeding roller 1, streaky polishing marks 6 along a circumferential direction are provided to an outer peripheral surface 5 of a cylindrical roller body 2 made of an elastic body. An image forming device incorporates the paper feeding roller 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a paper feed roller and an image forming apparatus incorporating the paper feed roller.

  For example, in various devices such as an image forming apparatus such as a laser printer using an electrophotographic method, an ink jet printer, and an automatic teller machine (ATM), paper such as paper or plastic film is conveyed (paper passing). In order to do this, a paper feed roller is used. Examples of the paper feed roller include a paper feed roller, a transport roller, a platen roller, and a paper discharge roller that rotate while contacting the paper and pass the paper by friction. The paper feed roller is generally configured by inserting and fixing a shaft through a central through hole of a cylindrical roller body made of an elastic material such as rubber or soft resin.

  In order to satisfy a predetermined outer diameter accuracy, the outer peripheral surface of the roller main body is directly ground using a grindstone or the like, and the outer peripheral surface has minute scale-like irregularities called polishing eyes. In general, the scale-like polishing marks are formed on the outer peripheral surface along the axial direction because of the characteristics of the grinding process. Further, it is known that the scale-like polishing marks along the axial direction function to increase the coefficient of friction of the outer peripheral surface with respect to the paper and improve the paper passing performance (see Patent Documents 1 and 2, etc.).

When paper is passed using a paper feed roller, paper dust is generated from the paper. The generated paper dust is accommodated in the recesses of the scale-like polishing eyes, or through the recesses to the outside of the outer peripheral surface of the roller body. It is discharged.
However, it is difficult for large paper dust of about 2 to 3 μm to be discharged, and when the outer peripheral surface of the roller body is repeatedly brought into contact with the paper for paper feeding, the outer peripheral surface is easily pressed against the outer peripheral surface by contact pressure with the paper or the like . When paper feeding is repeated, the number of paper powders that are press-bonded to the outer peripheral surface of the roller body increases, and the area where the paper powder is press-bonded on the outer peripheral surface is expanded. As a result, the area (contact area) where the outer peripheral surface of the roller body and the paper are in direct contact with each other without paper dust is reduced, resulting in a decrease in the friction coefficient of the outer peripheral surface and maintaining good paper passing performance. The problem arises that it becomes impossible.

JP-A-7-267395 Japanese Patent Laid-Open No. 10-273238

  The object of the present invention is to suppress the increase in the number of paper powders to be pressure-bonded to the outer peripheral surface of the roller body and the accompanying decrease in the friction coefficient of the outer peripheral surface even when paper feeding is repeated over a long period of time. An object of the present invention is to provide a paper feed roller capable of maintaining the paper passing performance and an image forming apparatus incorporating the paper feed roller.

The present invention includes a cylindrical roller main body made of an elastic body, and the outer peripheral surface of the roller main body is a paper feed roller having streak-like polishing eyes along the circumferential direction.
The present invention is also an image forming apparatus including the paper feed roller of the present invention.

  According to the present invention, even when paper feeding is repeated over a long period of time, an increase in the number of paper powders to be pressure-bonded to the outer peripheral surface of the roller main body and a decrease in the friction coefficient of the outer peripheral surface associated therewith are suppressed, It is possible to provide a paper feed roller capable of maintaining paper passing performance and an image forming apparatus incorporating the paper feed roller.

It is a perspective view which shows the external appearance of an example of embodiment of the paper feed roller of this invention. It is a stereoscopic microscope photograph which expands and shows the outer peripheral surface of a roller main body of the paper feed roller manufactured in Example 1 of this invention. It is a perspective view which shows the external appearance of an example of the conventional paper feed roller. 3 is a stereomicrograph showing an enlarged outer peripheral surface of a roller body of a conventional paper feed roller manufactured in Comparative Example 1; 4 is a stereomicrograph showing an enlarged outer peripheral surface of a roller body of a conventional paper feed roller manufactured in Comparative Example 2. 6 is a graph showing an example of a relationship between the number of sheets passing through and a friction coefficient in a paper feed roller.

FIG. 3 is a perspective view showing an appearance of an example of a conventional paper feed roller. FIG. 4 is a stereomicrograph showing an enlarged outer peripheral surface of a roller body of a conventional paper feed roller manufactured in a comparative example described later.
Referring to FIGS. 3 and 4, the conventional paper feed roller 11 includes a roller main body 12 formed in a cylindrical shape by an elastic material such as rubber and soft resin, and a through hole 13 at the center of the roller main body 12. And a shaft 14 inserted and fixed. The outer peripheral surface 15 of the roller main body 12 is in a state in which the scale portions 16 along the axial direction of the roller main body 12 are overlapped in the circumferential direction as a result of the outer peripheral surface 15 being ground using a grindstone or the like.

  In such a conventional paper feed roller 11, paper dust is accommodated in the concave portion 17 along the axial direction between the overlapping scaly portions 16. However, even if the paper dust accommodated in the recess 17 receives the rotational force in the circumferential direction intersecting with the recess 17 when the roller body 12 is rotated around the shaft 14, It is rare to be discharged smoothly. Not only that, but, for example, a large paper powder of about 2 to 3 μm is likely to be pressure-bonded to the step between the overlapping scale portions 16 or the concave portion 17 in the outer peripheral surface 15 due to the contact pressure accompanying the rotational force. When the paper feed is repeated, as described above, the number of paper powders pressed onto the outer peripheral surface of the roller main body increases, and the contact area between the outer peripheral surface of the roller main body and the paper decreases, resulting in friction of the outer peripheral surface. The coefficient decreases, and good paper passing performance cannot be maintained.

  FIG. 1 is a perspective view showing an appearance of an example of an embodiment of a paper feed roller of the present invention. Referring to FIG. 1, the paper feed roller 1 of this example is similar to the conventional example of FIG. 3, and includes a roller main body 2 formed into a cylindrical shape by an elastic material such as rubber or soft resin, and the roller main body 2. The shaft 4 is inserted into the central through hole 3 and fixed. In the drawing, one roller main body 2 on the paper feed roller 1 is shown in an enlarged manner. However, the paper feed roller 1 includes, for example, a plurality of roller main bodies 2 at a plurality of locations on one shaft 4. It can also be configured to be fixed.

FIG. 2 is a stereomicrograph showing an enlarged outer peripheral surface of the roller body of the paper feed roller manufactured in the example of the present invention. Referring to FIGS. 1 and 2, the outer peripheral surface 5 of the roller body 2 has a large number of streak-like polishing marks 6 along the circumferential direction.
The paper dust adhering to the outer peripheral surface 5 is accommodated in the recesses of the polishing eyes 6. Further, even if the paper dust accommodated in the concave portion is a large one of about 2 to 3 μm, the roller body 2 is attached to the shaft 4 while bringing the outer peripheral surface 5 into contact with the surface of the paper for paper feeding. Is rotated around the center of the outer peripheral surface 5, and is forcibly discharged smoothly out of the outer peripheral surface 5 through the recesses of the polishing eyes 6 along the same direction. The

Therefore, according to the paper feed roller 1 provided with the roller main body 2, even if paper feeding is repeated for a long period of time, the increase in the number of paper powders to be crimped to the outer peripheral surface of the roller main body and the accompanying outer peripheral surface 5 It is possible to maintain a good paper passing performance by suppressing a decrease in the friction coefficient.
The size of the polishing grain 6 is expressed by the surface roughness of the outer peripheral surface 5 in the axial direction. Japanese Industrial Standard JIS B0601 _{: 2001} “Product Geometrical Specification (GPS) —Surface Properties: Contour Curve Method—Terminology, Definition And the maximum height Rz of the contour curve specified in the “Surface property parameter”: 5 μm or more and 15 μm or less, the arithmetic average height Ra: 0.8 μm or more and 1.5 μm or less, and the average length RSm of the contour curve element : It is preferable that they are 5 micrometers or more and 15 micrometers or less.

  If the maximum height Rz, arithmetic average height Ra, or average length RSm of the contour curve elements in the axial direction of the outer peripheral surface 5 is less than the above range, the polishing eyes 6 are formed. The size of the concave and convex portions is insufficient. In addition, when any one of the maximum height Rz, the arithmetic average height Ra, or the average length RSm of the contour curve elements exceeds the above range, the convex and concave of the polishing eyes 6 are formed. When the portion protrudes too high and the outer peripheral surface 5 of the roller main body 2 comes into contact with the surface of the paper, it easily falls down due to contact pressure and closes the recess.

  Therefore, in any of these cases, a sufficient amount of paper dust is accommodated in the concave / convex recesses, or the stored paper dust is transferred to the outer peripheral surface 5 via the recesses as the roller body 2 rotates. There is a risk that it cannot be discharged smoothly. If paper feeding is repeated over a long period of time, the friction coefficient of the outer peripheral surface may be reduced due to paper dust or the like protruding from the recess, and it may not be possible to maintain good paper passing performance.

  On the other hand, by setting the maximum height Rz of the contour curve, the arithmetic average height Ra, and the average length RSm of the contour curve elements to be in the above ranges, the concave and convex concave portions constituting the polishing eyes 6 are The size can accommodate a sufficient amount of paper dust, and the convex portion can have a height that does not easily collapse due to contact pressure. Therefore, a sufficient amount of paper dust is accommodated in the concave and convex portions, or the accommodated paper dust is smoothly discharged out of the outer peripheral surface 5 through the concave portion as the roller body 2 rotates. Even if paper feeding is repeated over a long period of time, the increase in the number of paper powders pressed onto the outer peripheral surface of the roller body and the accompanying decrease in the coefficient of friction of the outer peripheral surface can be suppressed, and good passing can be achieved. Paper performance can be maintained.

  In consideration of further improving this effect, the maximum height Rz of the contour curve in the axial direction of the outer peripheral surface 5 is preferably 6 μm or more, and preferably 9 μm or less, even in the above range. preferable. In addition, the arithmetic average height Ra of the contour curve in the axial direction of the outer peripheral surface 5 is preferably 1 μm or more and preferably 1.3 μm or less even in the above range. Furthermore, the average length RSm of the contour curve elements in the axial direction of the outer peripheral surface 5 is preferably 7 μm or more, and preferably 12 μm or less, even in the above range.

  In order to form a large number of streak-like polishing marks 6 along the circumferential direction on the outer peripheral surface 5 of the roller main body 2, for example, the outer peripheral surface of the roller main body 2 formed in a cylindrical shape in advance using water-resistant abrasive paper, What is necessary is just to dry-grind. Further, in order to set the surface roughness in the axial direction of the outer peripheral surface 5 on which a large number of polishing marks 6 are formed within the above range, for example, it is used in accordance with the material and hardness of the roller body 2. What is necessary is just to select the count of water-resistant polishing paper, or to adjust polishing conditions such as polishing time and polishing pressure.

  The roller body 2 can be formed of a crosslinkable rubber, a non-crosslinkable thermoplastic elastomer, a soft resin, or the like, as in the past. Among these, examples of the crosslinkable rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), butyl rubber (IIR), acrylonitrile butadiene rubber (NBR), and ethylene. Propylene diene rubber (EPDM), chloroprene rubber (CR), acrylic rubber (ACM), chlorosulfonated polyethylene rubber (CSM), urethane rubber (U), silicone rubber (Q), fluoro rubber (FKM), epichlorohydrin rubber ( CO), polysulfide rubber (T), etc. 1 type or 2 types or more are mentioned. Further, as the non-crosslinkable thermoplastic elastomer, for example, one type or two types of various thermoplastic elastomers such as styrene type, olefin type, urethane type, polyester type, polyamide type, vinyl chloride type, fluorine type, etc. The above is mentioned. Furthermore, examples of the soft resin include soft resins such as ethylene vinyl acetate resin (EVA), soft polyester resin, low density polyethylene, and other resins that are soft per se, and plasticizers added to various resins. 1 type, or 2 or more types, such as various soft resins, such as what was converted.

Among these, among the crosslinkable rubbers, it is preferable to use EPDM alone (including a case where two or more kinds of EPDM are used in combination) or use EPDM and IR together. The mass ratio EPDM / IR in the latter combination system is preferably about 50/50 to 90/10.
As the EPDM, various EPDMs having crosslinkability in which a double bond is introduced into the main chain by adding a small amount of a third component (diene component) to ethylene and propylene can be used. As EPDM, various products are provided depending on the kind and amount of the third component. Representative examples of the third component include ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), dicyclopentadiene (DCP), and the like.

In addition, as EPDM, there are an oil-extended type in which flexibility is adjusted by adding an extending oil, and a non-oil-extended type in which flexibility is not added, and any of these can be used in the present invention.
One or more of these EPDMs can be used.
As the IR, various polymers having a polyisoprene structure and having crosslinkability can be used.

One or more of these IRs can be used.
When the roller body 2 is formed of a crosslinkable rubber, the rubber is blended with a crosslinking agent for crosslinking the rubber. Examples of the crosslinking agent include one or more of sulfur-based crosslinking agents, thiourea-based crosslinking agents, triazine derivative-based crosslinking agents, peroxide crosslinking agents, various monomers, and the like. In particular, in the case of EPDM alone or a combined system of EPDM and IR, a peroxide crosslinking agent is preferable as the crosslinking agent.

  Examples of the peroxide crosslinking agent include dibenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α'-di (t-butyl). Peroxy) diisopropylbenzene, t-butylcumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne- 3,1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) cyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, 2, 1 type such as 5-dimethyl-2,5-di (benzoylperoxy) hexane, t-hexylperoxybenzoate, t-butylperoxybenzoate Or 2 or more types are mentioned.

The blending ratio of the peroxide crosslinking agent can be appropriately set according to the rubber hardness of the roller body 2 after crosslinking.
In order to manufacture the paper feed roller 1 provided with the roller body 2 made of the rubber, first, a rubber composition is prepared by blending a rubber with a crosslinking agent and various additives and kneading them. Next, the prepared rubber composition is molded into a cylindrical shape by various molding methods such as press molding, transfer molding, injection molding, and extrusion molding, and the roller body 2 is formed by crosslinking the rubber.

  For example, in a molding method using a mold such as press molding, transfer molding, injection molding, etc., the rubber composition is filled in the mold, the mold is clamped, and the rubber composition corresponds to the outer shape of the roller body 2. In addition to molding into a cylindrical shape, the entire mold is heated to crosslink the rubber. In extrusion molding, a cylindrical body extruded into a cylindrical shape and cut into a predetermined length is heated in a vulcanizing can, for example, to crosslink the rubber, and then, if necessary, secondary crosslinking is performed. Thus, the roller body 2 is formed.

  Next, the formed roller body 2 is ground, polished or the like so as to have a predetermined outer diameter as necessary, and then the outer peripheral surface 5 of the roller body 2 is polished by the above-described polishing method or the like. A large number of streak-like polishing marks 6 are formed on the outer peripheral surface 5 along the circumferential direction. Further, at the same time that the roller body 2 is polished so as to have a predetermined outer diameter, the polishing marks 6 may be formed on the outer peripheral surface 5. At the same time, when the shaft 4 is inserted and fixed in the through hole 3, the paper feed roller 1 shown in FIG. 1 is manufactured.

The shaft 4 is integrally formed of a metal such as iron, aluminum, an aluminum alloy, and stainless steel.
In the molding method using a mold, the shaft 4 is inserted into the through hole 3 and fixed to the roller body 2 at any time after the roller body 2 is molded and after the outer peripheral surface 5 of the roller body 2 is polished. it can. Alternatively, the roller body 2 may be formed by so-called insert molding in which the rubber composition is filled in a state where the shaft 4 is set in a mold, and then molded and crosslinked, and the shaft 4 may be fixed. Further, in the extrusion molding, the shaft 4 can be inserted into the through hole 3 and fixed at any time after the cylindrical body is cut and after the outer peripheral surface 5 of the roller body 2 is polished.

  However, it is preferable to first grind the outer peripheral surface 5 with the shaft 4 inserted through the through hole 3. In extrusion molding, it is preferable to insert the shaft 4 through the through hole 3 prior to secondary crosslinking. Thereby, the curvature and deformation | transformation of the roller main body 2 by the expansion-contraction at the time of secondary bridge | crosslinking can be suppressed. Further, by polishing while rotating around the shaft 4, the workability of the polishing can be improved, and the deflection of the outer peripheral surface 5 can be suppressed.

  The shaft 4 having a larger outer diameter than the inner diameter of the through-hole 3 may be press-fitted into the through-hole 3 or may be inserted into the through-hole 3 before secondary crosslinking via an adhesive. In the former case, the mechanical fixing with the roller body 2 is completed simultaneously with the press-fitting of the shaft 4. In the latter case, the shaft 4 and the roller body 2 are mechanically fixed by drying, solidifying, or curing the adhesive. Further, both of them may be used together to mechanically fix the shaft 4 to the roller body 2.

As described above, the paper feed roller of the present invention is incorporated into various devices such as an image forming apparatus such as a laser printer using an electrophotographic method, an ink jet printer, an automatic teller machine (ATM), or the like. can do. In particular, it is preferably used by being incorporated in an image forming apparatus.
The image forming apparatus of the present invention is characterized in that the paper feed roller of the present invention is incorporated as, for example, a paper feed roller, a transport roller, a platen roller, a paper discharge roller, or the like. Examples of the image forming apparatus of the present invention include various image forming apparatuses using electrophotography such as a laser printer, an electrostatic copying machine, a plain paper facsimile machine, or a complex machine of these.

Hereinafter, the present invention will be further described based on examples, but the configuration of the present invention is not necessarily limited thereto.
<Example 1>
A rubber composition containing EPDM and a peroxide cross-linking agent is filled into a press mold and clamped, and heated at 160 ° C. for 20 minutes to crosslink the rubber, thereby forming a cylindrical roller body. Formed.

Next, in a state where the shaft is press-fitted and fixed in the through hole of the formed roller body, while rotating the roller body around the shaft, the outer peripheral surface of the roller body is water-resistant so as to have a predetermined outer diameter. A paper feed roller was manufactured by dry polishing using abrasive paper.
When the outer peripheral surface after polishing was observed using a stereomicroscope, it was confirmed that the outer peripheral surface had streak-like polished eyes along the circumferential direction of the roller body as shown in FIG. . Further, at any three points on the outer peripheral surface, the maximum height Rz of the contour curve, the arithmetic average height Ra, and the contour in the axial direction of the outer peripheral surface specified in the aforementioned Japanese Industrial Standard JIS B0601 _{: 2001} . When the average length RSm of the curved elements was obtained, the results shown in Table 1 were obtained.

<Comparative example 1>
The same rubber composition as in Example 1 was filled into a press mold and clamped, and heated at 160 ° C. for 20 minutes to crosslink the rubber to form a cylindrical roller body.
Next, in a state where the shaft is press-fitted and fixed in the through hole of the formed roller main body, while rotating the roller main body around the shaft, the outer peripheral surface of the roller main body is adjusted to have a predetermined outer diameter. Was used for grinding to produce a paper feed roller.

When the outer peripheral surface after grinding was observed using a stereomicroscope, as shown in FIG. 4, it was confirmed that the outer peripheral surface was in a state in which the scale-shaped portions along the axial direction of the roller body overlapped in the circumferential direction. It was done. Further, at any three points on the outer peripheral surface, the maximum height Rz, arithmetic average height Ra, and contour of the contour curve in the circumferential direction of the outer peripheral surface specified in the aforementioned Japanese Industrial Standard JIS B0601 _{: 2001} . When the average length RSm of the curved elements was measured, the results shown in Table 2 were obtained.

<Comparative example 2>
The same rubber composition as in Example 1 was filled into a press mold and clamped, and heated at 160 ° C. for 20 minutes to crosslink the rubber to form a cylindrical roller body.
Subsequently, although a shaft was press-fitted and fixed in the through hole of the formed roller main body, a paper feed roller was manufactured without polishing or grinding the outer peripheral surface of the roller main body.

When the outer peripheral surface was observed using a stereomicroscope, it was confirmed that the outer peripheral surface was in a substantially smooth state corresponding to the mold surface of the mold used for press molding, as shown in FIG. Further, at any three points on the outer peripheral surface, the maximum height Rz, arithmetic average height Ra, and contour of the contour curve in the circumferential direction of the outer peripheral surface specified in the aforementioned Japanese Industrial Standard JIS B0601 _{: 2001} . When the average length RSm of the curved elements was measured, the results shown in Table 3 were obtained.

<Real machine test>
The paper feed rollers manufactured in the examples and comparative examples were incorporated into a monochrome multifunction machine (HP LaserJet M4555h MFP manufactured by Hewlett-Packard Japan Co., Ltd.), and plain paper was continuously passed.
The initial friction coefficient μ ₀ , the friction coefficient μ _a1 after continuous feeding of 20000 sheets, and the friction coefficient μ _a2 after continuous feeding of 60000 sheets are respectively measured by the following measuring methods. Measured by.

(Measurement of friction coefficient)
A metal plate is installed horizontally, and the other end of the paper (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) with one end connected to the load cell is sandwiched between the metal plate and the paper feed roller. A vertical load W of 0.98 N (= 100 gf) was applied to the shaft of the paper feed roller.
In this state, under a temperature of 23 ± 2 ° C. and a relative humidity of 55 ± 10%, the paper feeding roller was rotated at a peripheral speed of 100 mm / second, and the conveyance force F (gf) applied to the load cell was measured.

Then, from the measured conveying force F and vertical load W (= 100 gf), equation (1):
μ = F × 0.01 (gf) / W (gf) (1)
Was used to determine the friction coefficient μ.
(Calculation of friction coefficient retention coefficient S)
According to the inventor's study, the friction coefficient of the paper feed roller follows the process indicated by the solid curve in FIG. 6 as the number of paper powders pressed against the outer peripheral surface of the roller body by passing paper increases. That is, the friction coefficient rapidly decreases from the initial μ ₀ when paper dust starts to be pressed onto the outer peripheral surface as paper starts, and decreases as the number of paper powder pressed onto the outer peripheral surface approaches saturation. Shows a tendency to gradually become gradual.

For example, an increase in the number of paper powders to be pressed against the outer peripheral surface of the roller body and a corresponding decrease in the friction coefficient of the outer peripheral surface when paper feeding is repeated between 0 and a ₂ sheets. Whether or not good paper passing performance can be suppressed is determined by the area of the area surrounded by the vertical and horizontal axes in FIG. 6, the curve, and the vertical broken line passing through a ₂ on the horizontal axis. . In other words, the larger the area, the better the paper passing performance can be maintained.

Therefore, the inventors, in order to evaluate the magnitude of possible simplified manner area, the curve, as indicated by one-dot chain lines in the figure, the middle, is approximated by a straight line bent at the time of number of fed sheets a ₁ The area of the previous period from the number of sheets passed through 0 to a ₁ sheet S ₁ = (μ ₀ + μ _a1 ) × a ₁ ÷ 2 (2)
When the area of late from _one number of fed sheets _a to _{two a S 2 = (μ a1 +} μ a2) × (a 2 -a 1) ÷ 2 (3)
And asked. And equation (4)
S = S ₁ + S ₂ (4)
The total area S obtained in the above is used as a friction coefficient retention coefficient, and it is determined whether it is possible to maintain good sheet passing performance from 0 sheets to a ₂ sheets by compensation.

In consideration of general service sheet passing number of the paper feed roller or the like in an image forming apparatus, as described above, a ₂ 60000 sheets, a ₁ is set at 20,000 sheets.
The evaluation results are shown in Table 4. In the table, the friction coefficient retention coefficient S is indicated by a numerical value of 1/1000.

  From the results of Table 4, Example 1 in which streak-like abrasives along the circumferential direction are formed on the outer peripheral surface of the roller body is the comparative example 1 in which scale-like abrasives along the axial direction are formed, and a comparatively smooth comparison. Compared to Example 2, even when paper feeding is repeated over a long period of time, the increase in the number of paper powders to be pressure-bonded to the outer peripheral surface of the roller body and the accompanying decrease in the friction coefficient of the outer peripheral surface are suppressed. It was found that the paper passing performance can be maintained.

1 paper feed roller 2 roller body 3 through hole 4 shaft 5 the outer peripheral surface 6 polishing marks _a 1, _{a 2} number of fed sheets μ _0, μ _a1, μ _a2 coefficient of friction

Claims (3)

  A paper feed roller including a cylindrical roller main body made of an elastic body, and an outer peripheral surface of the roller main body having a streak-like polishing eye along the circumferential direction. As for the said outer peripheral surface, the surface roughness of an axial direction is prescribed | regulated in Japanese Industrial Standard JISB0601 _{: 2001} , The maximum height Rz of a contour curve: 5 micrometers or more, 15 micrometers or less, arithmetic mean height Ra: 0.8 micrometers or more, 2. The paper feed roller according to claim 1, which is 1.5 μm or less and has an average length RSm of the contour curve element of 5 μm or more and 15 μm or less.   An image forming apparatus including the paper feed roller according to claim 1.