JPH101578A - Sheet feeding roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet feeding roller which has high coefficient of friction, is flexible and excellent in sheet conveying ability, and also has high wear resistance and excellent ozone resistance by forming a rubber layer comprising a specified material with a specified thickness as the outermost surface layer of a roller. SOLUTION: This roller 1 is provided with an inner layer 11 comprising a foam (e.g. polyurethane foam) having a spring hardness (measured with Asker hardness tester model C) of at most 15 and a surface layer 12 formed by laminating around the inner layer 11 and containing base rubbers comprising a polynorbornene rubber and an ethylene/propylene/diene copolymer rubber, wherein the thickness T1 of the surface layer 12 is at least 0.3mm and at most 40% of the total thickness (T1 +T2 ) of the layers 11 and 12. It is desirable that the average surface roughness of the layer 12 is at most 50μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrostatic copying machine, a laser printer, a plain paper facsimile machine, or an automatic teller machine (AT).
M) relates to a paper feed roller used for paper feed.

[0002]

2. Description of the Related Art Paper feed rollers, transport rollers, platen rollers, paper discharge rollers, etc. of the above-mentioned image forming apparatus,
Conventionally, paper feed rollers such as those for bills and slips in M have a high coefficient of friction on their surfaces in order to obtain a high conveying force and to prevent slippage on paper. The contact length (L _{1 in} FIG. 3) when the paper feed roller is compressed and deformed by being pressed against the paper is multiplied by the width of the paper feed roller to increase the contact area. In addition, it is required to have high abrasion resistance in order to suppress abrasion when repeatedly fed, and especially when used in an image forming apparatus, the inside of the image forming apparatus has a low ozone concentration. It is also required to be excellent in ozone resistance because it tends to be in a high state.

It is effective to add a plasticizer to increase the flexibility of the paper feed roller in order to satisfy the above-mentioned requirements. However, the addition of the plasticizer lowers the wear resistance of the paper feed roller. At the same time, there is a problem that the plasticizer oozing out on the surface stains the paper (a trace of a roller is formed on the paper). Therefore, studies have been made to increase the flexibility of the paper feed roller by using a foamed structure.

[0004]

For example, U.S. Pat. No. 4,287,649 discloses a paper feed roller made of foamed polyurethane rubber or the like whose surface is thinly coated with polyurethane or the like. JP-A-6-337610 discloses a paper feed roller in which a surface layer made of fluororesin is laminated on the outer periphery of an inner layer made of foamed silicone rubber. Further, JP-A-6-23948
No. 5 discloses a paper feed roller made of foamed rubber, which uses a non-foamed surface skin layer as a wear-resistant surface layer, which is inevitably generated when foaming rubber.

However, none of the above-mentioned materials can satisfy all of the above-mentioned various requirements because the material properties of the inner layer and the surface layer or the mechanical and physical properties are not properly set. is there. The present invention has a high coefficient of friction, is flexible, has a large paper contact area when pressed against paper at a predetermined pressure, has excellent paper transportability, and has high abrasion resistance and ozone resistance. Another object of the present invention is to provide a paper feed roller having excellent properties.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have developed a paper feed roller having a two-layer structure including an inner layer made of a foam and a surface layer laminated and formed on the outer periphery of the inner layer. In order to optimize the characteristics of the inner layer and the surface layer, a study was conducted. As a result, a surface layer containing polynorbornene rubber and ethylene-propylene-diene copolymer rubber (EPDM) as a base rubber,
It has been found that it may be combined with an inner layer made of a flexible foam.

In other words, the polynorbornene rubber has a high coefficient of friction and is flexible in itself, and even in a flexible composition in which a small amount of a reinforcing agent such as white carbon or a filler such as calcium carbonate is added, the material itself can be used. Sufficient abrasion resistance can be exhibited by the characteristics of.
Therefore, if this polynorbornene rubber is combined with EPDM having excellent ozone resistance to form a surface layer, such a surface layer has excellent wear resistance and ozone resistance, has a high friction coefficient, and is flexible. Since there is no risk of impairing the flexibility of the inner layer made of the foam, the paper contact area when pressed against paper at a predetermined pressure is large, and a flexible paper feed roller excellent in paper transportability can be configured. Was found.

The inventors have further studied the degree of flexibility of the inner layer combined with the above-mentioned surface layer and the preferred range of the thickness of the surface layer, and as a result, have completed the present invention. That is, the paper feed roller of the present invention uses an inner layer made of a foam having a spring hardness (Asker C) of 15 ° or less, and polynorbornene rubber and EPDM laminated and formed on the outer periphery of the inner layer as base rubbers. And a surface layer containing 0.3 mm thick
As described above, the thickness is 40% or less of the total thickness of the inner layer and the surface layer.

In the paper feed roller of the present invention having the above structure, the hardness of the inner layer is the spring hardness (Asker C).
The reason is that if the inner layer is harder than this, the flexibility of the paper feed roller as a whole is reduced, and the paper contact area when pressed against the paper with a predetermined pressure is reduced, This is because the transportability is reduced. The thickness of the surface layer is 0.3 mm
Is being limited to the above, above which the surface layer is thin, is the smoothness of the surface layer surface is lowered by the influence of the inner layer of the unevenness of the paper feed roller in contact length L ₁ as described above for the foam This is because, even if the apparent paper contact area obtained by multiplying the width is the same, the substantial paper contact area is reduced, and the paper transportability is reduced.

Furthermore, the reason why the thickness of the surface layer is limited to 40% or less of the total thickness of the inner layer and the surface layer is that if the surface layer is thicker than this, the flexibility of the surface layer is reduced and the flexibility of the inner layer is hindered.
As a result, the flexibility of the entire paper feed roller is reduced, the contact area is reduced, and the paper transportability is reduced.
Here, the spring hardness (Asker C) is a spring hardness measured by a spring type rubber / plastic hardness meter (Asker C type hardness meter) manufactured by Kobunshi Keiki Co., Ltd.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. The paper feed roller 1 of the present invention includes an inner layer 11 and a surface layer 12 laminated and formed on the outer periphery of the inner layer 11, as shown in FIGS. In FIG.
Is a core of the roller.

The paper feed roller 1 having the inner layer 11 and the surface layer 12 is not limited to the above. For example, a rubber composition (base rubber) serving as a base of the surface layer 12 is formed on the outer peripheral surface of the previously formed inner layer 11. A solution of polynorbornene rubber and EPDM to which various additives such as a vulcanizing agent are added) is applied, dried, and then heated and vulcanized to form the surface layer 12. The above rubber composition Is formed into a sheet shape or a cylindrical shape, heated and vulcanized, and wound around an outer peripheral surface of the previously formed inner layer 11 with an adhesive to form a surface layer 12. Foaming which forms the inner layer The rubber composition is extruded in two layers from a material having an elasticity and the above rubber composition, and the inner layer is foamed together with heating and vulcanization to form the inner layer 11 and the surface layer 12.

As described above, the inner layer 11 is formed of a foam having a spring hardness (Asker C) of 15 ° or less. The reason why the hardness of the foam is limited to the above range is as described above. Note that the lower limit of the spring hardness (Asker C) of the inner layer 11 may be 0 ° as is clear from the results of the examples described later. In order to adjust the hardness of the inner layer 11 to the above range, for example, the material of the foam, the expansion ratio, the foam structure and the like may be appropriately changed. Note that the foam structure of the foam is preferably an open-cell structure rather than a closed-cell structure, particularly in consideration of the restoring force of the foam after compression.

Preferred examples of the foam include, but are not limited to, foamed polyurethane and the like. The thickness T ₂ of the inner layer 11 made of the foam is not particularly limited in the present invention, considering the flexibility and the paper feed roller, a predetermined amount of deformation when it is pressed against the paper with a pressure, and thus contact area, etc. Then, it is preferable that it is about 5 to 30 mm.

The surface layer 1 laminated and formed on the outer periphery of the inner layer 11
2 is, as described above, polynorbornene rubber and EPD
And M as a base rubber. The thickness T _{1 of the} surface layer 12 is 0.3 mm as described above.
As described above, the total thickness of the inner layer 11 and the surface layer 12 (T ₁ +
T ₂ ) is limited to a range of 40% or less. The reason is as described above.

The thickness of the surface layer 12 is preferably within the above range, considering the improvement of the paper transportability due to the improvement of the smoothness of the surface of the surface layer 12 and the improvement of the flexibility of the surface layer 12. Total thickness of inner layer 11 and surface layer 12 (T ₁ + T
_It is preferably at least 10% of ₂ ). The surface layer 1
2 preferably has a surface as smooth as possible,
Although not limited thereto, for example, it is preferable that the average value of the surface roughness indicating the smoothness of the surface layer 12 is 50 μm or less. If the average value of the surface roughness exceeds 50 μm, the smoothness of the surface of the surface layer 12 is reduced. May be reduced. The average value of the surface roughness can be obtained by measuring the depth of the concave portion at at least five places on the surface of the surface layer 12 and averaging the measured depths.

The polynorbornene rubber forming the surface layer 12 is formed into a rubbery state by adding a petroleum-based oil or the like as a softening agent to a resinous polymer (polynorbornene) obtained by ring-opening polymerization of norbornene. Things. Specific examples of the polynorbornene rubber include, but are not limited to, Nosorex NSX manufactured by Zeon Corporation.
15NB [rubber component / softener (naphthenic oil) = 10
0/150 (weight ratio)].

EPDM to be combined with the above-mentioned polynorbornene rubber includes various oil-extended or non-oil-extended diene compounds whose components are ethylidene norbornene (ENB), 1,4-hexadiene or dicyclopentadiene (DCPD). EPDM can be used. Specific examples of such EPDM include, but are not limited to, Esplen E505A (non-oil-extended EPDM) manufactured by Sumitomo Chemical Co., Ltd.

The mixing ratio of the above polynorbornene rubber and EPDM is not particularly limited in the present invention. For example, when the polynorbornene rubber is used in an image forming apparatus, it may be appropriately set according to the ozone concentration at the place of use. typically, a polynorbornene amount of rubber component in the rubber (amount of polynorbornene excluding the softener) W _N, the ratio W _N / W _E of the amount W _E of _{EPDM, W N / W E =} 80 / 20-70 / 30
It is preferable that both are blended so as to be about (weight ratio).

When the amount of polynorbornene rubber is larger than the above range and the amount of EPDM is small, the effect of improving ozone resistance due to the addition of EPDM may not be sufficiently obtained. Conversely, even if the polynorbornene rubber is less than the above range and the EPDM is increased, the effect of improving ozone resistance cannot be expected anymore,
Since the polynorbornene rubber is relatively small, the friction coefficient, flexibility and abrasion resistance of the surface layer may be reduced.

As the additives to be added to the rubber composition containing the polynorbornene rubber and EPDM as base rubbers, in addition to the vulcanizing agents, for example, a vulcanization accelerator, a vulcanization accelerator, a vulcanization accelerator, Examples include retarders, anti-aging agents, reinforcing agents, fillers, softeners, plasticizers and the like. Among the above, examples of the vulcanizing agent include sulfur, organic sulfur-containing compounds, organic peroxides, and the like. Examples of the organic sulfur-containing compound include N, N'-dithiobismorpholine and the like. Examples of the peroxide include benzoyl peroxide, dicumyl peroxide and the like.

Examples of the vulcanization accelerator include thiuram vulcanization accelerators such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, dimethyl Dithiocarbamic acids such as sodium dithiocarbamate and tellurium diethyldithiocarbamate; thiazoles such as 2-mercaptobenzothiazole, dibenzothiazyldisulfide, N-cyclohexyl-2-benzothiazolesulfenamide; trimethylthiourea; Organic promoters such as thioureas such as N'-diethylthiourea,
Alternatively, inorganic accelerators such as slaked lime, magnesium oxide, titanium oxide, and litharge (PbO) can be used.

Examples of the vulcanization accelerator include metal oxides such as zinc white, stearic acid, oleic acid, and the like.
And fatty acids such as cottonseed fatty acids. Examples of the vulcanization retarder include aromatic organic acids such as salicylic acid, phthalic anhydride and benzoic acid; N-nitrosodiphenylamine,
And nitroso compounds such as -nitroso-2,2,4-trimethyl-1,2-dihydroquinone and N-nitrosophenyl-β-naphthylamine.

Examples of antiaging agents include imidazoles such as 2-mercaptobenzimidazole; phenyl-α-naphthylamine, N, N'-di-β-naphthyl-
amines such as p-phenylenediamine and N-phenyl-N'-isopropyl-p-phenylenediamine; di-t
-Butyl-p-cresol, and phenolized nophenols.

As the reinforcing agent, white inorganic reinforcing agents such as white carbon, zinc white, surface-treated precipitated calcium carbonate, magnesium carbonate, clay and the like are mainly used in order not to stain the paper to be conveyed. Organic reinforcing agents such as malonindene resin, phenolic resin and high styrene resin (styrene-butadiene copolymer having a high styrene content) can also be used.

Examples of the filler include calcium carbonate, clay, barium sulfate, diatomaceous earth and the like.
Examples of the softener include vegetable oil-based, mineral oil-based, and synthetic softeners such as fatty acids (such as stearic acid and lauric acid), cottonseed oil, tall oil, asphalt substances, and paraffin wax.

Further, examples of the plasticizer include various plasticizers such as dibutyl phthalate, dioctyl phthalate, and tricresyl phosphate. In addition to the above, for example, a dispersant, a solvent, and the like may be appropriately compounded in the base rubber. The rubber composition is manufactured by kneading the above components using, for example, an open roll, a closed kneader, or the like.

[0028]

The present invention will be described below with reference to examples and comparative examples. The rubber composition for the surface layer used in Examples and Comparative Examples was prepared as follows. Preparation of Rubber Composition I Polynorbornene rubber [Nosorex NSX
15NB] 187.5 parts by weight (amount of rubber component W _N = 75
Parts by weight) and non-oil-extended EPDM [Esprene E50 mentioned above]
5A] 25 parts by weight as a base rubber;
The following components were added to 2.5 parts by weight, and kneaded to prepare a rubber composition I for a surface layer.

[0029] Preparation of Rubber Composition II Oil-extended EPDM [Esprene E600 manufactured by Sumitomo Chemical Co., Ltd.]
F, rubber component / extending oil = 100/100 (weight ratio)] as a base rubber, and the following components are blended and kneaded with 200 parts by weight of the base rubber, and the rubber composition for the surface layer is kneaded. II was prepared.

<< Ingredient >><< Addition amount >><Reinforcingagent> Silica [Nipsil VN3 described above] 20 parts by weight <Vulcanizing agent> Powdered sulfur 2 parts by weight <Vulcanization accelerator> Tetraethylthiuram disulfide [Noxeller described above] TET] 1 part by weight zinc dibutyldithiocarbamate [Noxeller BZ manufactured by Ouchi Shinko Chemical Co., Ltd.] 2 parts by weight N-cyclohexyl-2-benzothiazolylsulfenamide [Noxeller CZ manufactured by Ouchi Shinko Chemical Co., Ltd.] 1 part by weight <vulcanization accelerator> Zinc flower # 1 5 parts by weight Stearic acid 1 part by weight Preparation of rubber composition III Silicone rubber compound [Toray Dow Corning Co., Ltd.]
SE1140U manufactured by Silicone Co., Ltd.] was used as a base rubber, and a vulcanizing agent [RC-41 manufactured by Dow Corning Toray Silicone Co., Ltd.] was used for 100 parts by weight of the base rubber.
40] 1.3 parts by weight were compounded and kneaded to prepare a rubber composition III for a surface layer.

Examples 1 to 3 and Comparative Example 1 A plastic core having an outer diameter of 16 mm was set at the center, and was placed in a mold for forming an inner layer having an outer diameter of 30 mm, a width of 18 mm and a thickness T ₂ = 7 mm. A two-component type foamed polyurethane was poured, foamed and cured to form an inner layer having the above dimensions and the spring hardness (Asker C) shown in Table 1 on the outer peripheral surface of the core. .

The hardness of the inner layer was adjusted by adjusting the mixing ratio of water and catalyst in the polyurethane foam. In the above-mentioned forming method, a very thin skin layer (non-foamed layer) is formed on the outer peripheral surface of the inner layer. However, this skin layer is left without being removed because it is convenient for bonding the surface layer. The hardness of the inner layer was measured by an Asker C type hardness meter manufactured by Kobunshi Keiki Co., Ltd. as described above.
Since the surface is a curved surface, the variation due to measurement is large, and ±
2 ° was within the allowable range.

Next, the rubber composition I was formed into a sheet, vulcanized at 170 ° C. for 20 minutes, and then laminated and bonded to the outer periphery of the inner layer via a urethane-based adhesive. Polish the surface to form a surface layer with a thickness,
Outer diameter 32 ± 0.3 mm, width 18 mm, thickness of inner layer T ₂ =
A paper feed roller having a thickness of 7 mm and a surface layer thickness T _{1 of 1} mm was manufactured.

Comparative Examples 2 and 3 Instead of the rubber composition I, the rubber composition II (Comparative Example 2)
Alternatively, a paper feed roller was manufactured in the same manner as in Examples 1 to 3 and Comparative Example 1 except that the rubber composition III (Comparative Example 3) was used. The spring hardness (Asker C) of the inner layer of both comparative examples was 5 °.

With respect to the paper feed rollers of the above Examples and Comparative Examples, the following tests were performed to evaluate the characteristics. Measurement of Coefficient of Friction As shown in FIG. 2, a paper 3 having one end connected to a digital force gauge 2 was placed on a plate 4 on which a Teflon sheet or the like was stuck to suppress friction.

Next, the paper feed roller 1 manufactured from the silicone rubber compositions of Examples and Comparative Examples was set on the rotating shaft 5 disposed above the plate 4, and was placed on the plate 4 as indicated by black arrows in the figure. It was brought into pressure contact with a load W ₁ (= 200 g). Next, the rotating shaft 5 is rotated at a constant speed in the direction indicated by the two-dot chain line arrow in the drawing so that the peripheral speed of the paper feed roller 1 becomes 100 mm / sec. Is continuously measured by the digital force gauge 2 for 30 seconds, and the peak value F _{1 is obtained.}
(G) and the load W ₁ , the following formula:

[0037]

(Equation 1)

Thus, the friction coefficient μ was determined. Measurement of paper contact length As shown in FIG. 3, the paper feed rollers 1 of the embodiment and the comparative example were set on the shaft 6, and the plate 7 as indicated by the black arrow in the figure.
Were pressed against each other by applying a load W ₂ (= 200 g).

Then, the length L ₁ of the paper contact was measured in mm units. Measurement of Surface Roughness The paper feed rollers of Examples and Comparative Examples were cut in a direction perpendicular to the axial direction, and the depth of the concave portion was measured at five places on the surface of the surface layer 12 among the cut surfaces, and each measured value was measured. , The average value of the surface roughness was determined.

Table 1 shows the above results. T% in the table
Is the formula:

[0041]

(Equation 2)

The thickness T ₁ (m) of the surface layer with respect to the total thickness T ₁ + T ₂ (mm) of the inner layer and the surface layer obtained by
m).

[0043]

[Table 1]

From Table 1, the spring hardness (Asker C)
Examples 1 to 3 including an inner layer made of a foam having a temperature of 15 ° or less, and a surface layer formed from the rubber composition I,
It was found that compared to Comparative Example 1 in which the same surface layer was combined with an inner layer having a spring hardness (Asker C) of more than 15 °, the paper contact length was longer and the friction coefficient μ was larger. From this result, the inner layer spring hardness (Asker C)
Was found to need to be 15 ° or less.

In each of the above Examples, although the same inner layer was combined with a surface layer formed of the rubber composition II or III, Comparative Examples 2 and 3 had the same length of paper contact, but had a friction coefficient of It turned out that μ was large. As a cause of this, it is considered that the polynorbornene rubber itself has a high friction coefficient as described above, and from this result, it was confirmed that the surface layer needs to contain the polynorbornene rubber as a base rubber.

Further, the rubber composition I used in the examples,
Each of the rubber composition IV and the rubber composition IV from which the EPDM was removed was vulcanized to prepare a sheet-shaped sample, and left in an ozone atmosphere at an ozone concentration of 25 pphm and a temperature of 40 ° C. for 96 hours. Observation of the presence or absence of a crack after elongation by 10% revealed that the sample produced from rubber composition IV had cracks, but the sample produced from rubber composition I did not crack. And from this result, it was confirmed that the surface layer needed to contain not the polynorbornene rubber alone but EPDM.

Examples 4 to 6, Comparative Examples 4 and 5 The thickness of the surface layer was 0.1 mm (T% = 1.25%, Comparative Example 4) and 0.3 mm (T% = 3.75%, Example 4). ),
1.5 mm (T% = 18.75%, Example 5), 3 mm
(T% = 37.5%, Example 6) and 5 mm (T%
= 62.5%), and a paper feed roller was manufactured in the same manner as in Examples 1 to 3 and Comparative Example 1. The spring hardness (Asker C) of the inner layer of each of the examples and comparative examples was set to 5 °.

In Comparative Example 4 and Example 4, it was difficult to adjust the surface layer to the appropriate thickness by polishing the sheet. Therefore, the surface layers having the corresponding thickness were prepared and bonded to the outer periphery of the inner layer. In Comparative Example 5, since it was difficult to wind the sheet-shaped surface layer around the outer periphery of the inner layer, the surface layer preliminarily vulcanized and formed into a tubular shape was adhered to the inner layer.

Comparative Example 6 An inner layer was not formed and a thickness of 8 mm (T
% = 100%) except that the surface layer was formed.
3. A paper feed roller was manufactured in the same manner as in Comparative Example 1. As in the case of Comparative Example 5 above, the surface layer was vulcanized and molded in a tubular shape in advance and the core layer was covered with and bonded to the core.

The above-described tests were performed for each of the above Examples and Comparative Examples. The results are shown in Table 2 together with the results of Example 2.

[0051]

[Table 2]

From Table 2, it is found that Examples 2, 4 to 4 in which the thickness of the surface layer is not less than 0.3 mm and not more than 40% in terms of T%.
In each of Comparative Examples 6, the length of the paper contact was almost the same as in Comparative Example 4 in which the thickness of the surface layer was less than 0.3 mm, but the friction coefficient μ was large. This is because, in Comparative Example 4, where the surface layer is thin, the smoothness of the surface layer surface is reduced due to the influence of the unevenness of the inner layer which is a foam, and therefore, even though the apparent paper contact area is the same, the substantial paper contact area is reduced. Is considered to be the cause. The reason is that the surface roughness of Comparative Example 4 is significantly larger than that of each Example. And from these results, the thickness of the surface layer is 0.3 mm
It was confirmed that this was necessary.

In each of the above Examples, the contact length is longer and the friction coefficient μ is larger than those of Comparative Examples 5 and 6 in which the thickness of the surface layer exceeds 40% in T%. all right. And from this result, it was confirmed that the thickness of the surface layer needs to be 40% or less in T%.

[0054]

As described above in detail, according to the present invention, the paper has a high friction coefficient, is flexible, and has a large paper contact area when pressed against paper at a predetermined pressure. It is possible to provide a paper feed roller that is excellent and has high abrasion resistance and excellent ozone resistance.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an embodiment of a paper feed roller according to the present invention, wherein FIG. 1 (a) is a side view of the paper feed roller and FIG. 1 (b) is a perspective view.

FIG. 2 is a diagram illustrating a method for measuring a friction coefficient μ of a paper feed roller manufactured in an example of the present invention and a comparative example.

FIG. 3 is a diagram for explaining a method for measuring a paper contact length of a paper feed roller manufactured in the example and the comparative example.

[Explanation of symbols]

 1 paper feed roller 11 inner layer 12 surface layer

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08L 65/00 LNY C08L 65/00 LNY

Claims (2)

[Claims] 1. An inner layer made of a foam having a spring hardness (Asker C) of 15 ° or less, and a polynorbornene rubber and an ethylene-propylene-diene copolymer rubber laminated and formed on the outer periphery of the inner layer. And a surface layer containing as material rubber, the thickness of the surface layer is 0.3 mm
The paper feed roller described above, wherein the thickness is 40% or less of the total thickness of the inner layer and the surface layer. 2. The paper feed roller according to claim 1, wherein the average value of the surface roughness of the surface layer is 50 μm or less.