Paper feed roll

Abstract

To provide a paper feed roll capable of suppressing occurrence of non-uniform wear for each part on a surface of an elastic layer, exhibiting, even after long-time use, an excellent sheet-conveyance property, and avoiding sheet jamming, even though the elastic layer includes a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber.SOLUTION: A paper feed roll 10 comprises: a shaft body 12; and an elastic layer 14 formed on an outer periphery of the shaft body. The elastic layer contains a polymer and hydrophobic silica having an octylsilyl group, and a content of the hydrophobic silica is 1-20 pts.mass with respect to 100 pts.mass of the polymer. The elastic layer has: a first phase containing ethylene propylene diene rubber; and a second phase containing at least one of isoprene rubber and natural rubber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a paper feed roll that is suitably used in electrophotographic devices such as copying machines, printers, and facsimiles that employ an electrophotographic system. [Background technology]

[0002] A paper feed roll is known that has an elastic layer made of an elastic material such as a cross-linked rubber on the outer circumferential surface of a shaft such as a core metal. Known elastic materials for the elastic layer include those that use a combination of ethylene propylene diene rubber and isoprene rubber or styrene butadiene rubber (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-196428 Summary of the Invention [Problem to be solved by the invention]

[0004] When the elastic material of the elastic layer is composed of two or more polymer components, the elastic layer is often composed of two or more phases with different polymer components. Because the polymer components are different, the amount of wear and the amount of paper dust that adheres to each phase differs. As a result, after long-term use, the difference in the friction coefficient between the phases becomes greater, and the elastic layer is prone to having an uneven surface friction coefficient. If the friction coefficient of the elastic layer is uneven, paper cannot be transported straight, resulting in problems such as poor transport (paper jams).

[0005] The problem to be solved by the present invention is to provide a paper feed roll that has an elastic layer that has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber, but that suppresses uneven wear at each part of the surface of the elastic layer, has excellent paper transport properties even after long-term use, and can avoid paper jams. [Means for solving the problem]

[0006] The paper feed roll according to the present invention comprises a shaft body and an elastic layer formed on the outer periphery of the shaft body, the elastic layer containing a polymer and hydrophobic silica having an octylsilyl group, the content of the hydrophobic silica being 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the polymer, and the elastic layer having a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber.

[0007] In the elastic layer, the area ratio of the second phase is preferably in the range of 30 to 70% within any 2.5 μm×2.5 μm square area of ​​the elastic layer. The elastic layer preferably further contains a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of either isoprene rubber or natural rubber. A partial structure of the ethylene propylene diene rubber is preferably an ethylene propylene structure. The elastic layer preferably further contains a hydrocarbon oil. The ethylene propylene diene rubber preferably contains both oil-extended ethylene propylene diene rubber and non-oil-extended ethylene propylene diene rubber. It is further desirable that the hydrophobic silica of the elastic layer be unevenly distributed in a larger amount in the first phase than in the second phase. [Effects of the Invention]

[0008] The paper feed roll for electrophotographic equipment according to the present invention includes a shaft and an elastic layer formed on the outer periphery of the shaft. The elastic layer contains a polymer and hydrophobic silica having octylsilyl groups, with the hydrophobic silica content being 1 to 20 parts by weight per 100 parts by weight of the polymer. The elastic layer has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber. This reduces surface wear of the elastic layer after long-term use, ensuring consistent wear across the elastic layer. Furthermore, the coefficient of friction of the elastic layer is unlikely to change even if paper dust adheres to the surface, eliminating differences in the coefficient of friction across the elastic layer. As a result, paper transport problems (paper jams) after long-term use can be eliminated. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a schematic view of the appearance of a paper feed roll according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA thereof. [Figure 2] FIG. 2 is a schematic diagram showing a method for measuring the area ratio of both the first phase and the second phase in the elastic layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] The paper feed roll according to the present invention will be described in detail below. Figure 1 shows a schematic view (a) of the appearance of a paper feed roll according to one embodiment of the present invention, and (b) a cross-sectional view taken along line AA.

[0011] The paper feed roll 10 according to one embodiment of the present invention includes a shaft 12 and an elastic layer 14 formed on the outer peripheral surface of the shaft 12. The elastic layer 14 is a layer (base layer) that serves as the base of the paper feed roll 10. The elastic layer 14 is a layer that appears on the surface of the paper feed roll 10.

[0012] The shaft 12 may be a solid body or a hollow body (cylinder) made of metal or resin. Examples of metal materials include iron, stainless steel, and aluminum. The elastic layer 14 may be adhered to the shaft 12 via an adhesive layer (primer layer). The adhesive, primer, etc. may be made conductive as necessary.

[0013] The elastic layer 14 contains a polymer and hydrophobic silica having an octylsilyl group, and the content of the hydrophobic silica is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the polymer. The elastic layer has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber.

[0014] In the elastomer layer 14, the first phase containing ethylene propylene diene rubber is suitable for adjusting the hardness of the elastomer layer 14 to a desired range. The second phase containing at least one of isoprene rubber (IR) and natural rubber (NR) has a higher coefficient of friction than the first phase containing ethylene propylene diene rubber and is suitable for improving the coefficient of friction on the surface of the elastomer layer 14. The presence of the first and second phases results in different amounts of paper dust adhering to the surface of the elastomer layer 14, making it suitable for maintaining the coefficient of friction over a long period of time. Hydrophobic silica containing octylsilyl groups is suitable for maintaining the coefficient of friction because the octylsilyl groups are suitable for maintaining the coefficient of friction, and its hydrophobicity makes it suitable for preventing the adhesion of paper dust. Therefore, it is suitable for maintaining the coefficient of friction by suppressing wear of the elastomer layer 14 (particularly the first phase) and the adhesion of paper dust. The amount of hydrophobic silica is 1 to 20 parts by mass per 100 parts by mass of the first and second phase polymers, which suppresses surface wear of the elastic layer 14 after long-term use, so the amount of wear does not vary depending on the area on the surface of the elastic layer.In addition, even if paper dust adheres to the surface of the elastic layer, the coefficient of friction does not change easily, so there is no difference in the coefficient of friction depending on the area on the surface of the elastic layer.As a result, paper transport problems (paper jams) after long-term use can be eliminated.

[0015] Ethylene propylene diene rubber is a copolymer of ethylene and propylene, ethylene propylene rubber (EPM), with a non-conjugated diene as a third component. Ethylene propylene diene rubber has an ethylene propylene structure and a structure resulting from the non-conjugated diene within its molecular structure. Examples of non-conjugated dienes in ethylene propylene diene rubber include ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), and dicyclopentadiene (DCPD).

[0016] The ethylene propylene diene rubber may be an oil-extended ethylene propylene diene rubber or a non-oil-extended ethylene propylene diene rubber. The ethylene propylene diene rubber may contain both an oil-extended ethylene propylene diene rubber and a non-oil-extended ethylene propylene diene rubber. From the viewpoints of easily applying sufficient shear during rubber kneading and improving the dispersibility of the second phase in the first phase, it is preferable that the ethylene propylene diene rubber contain both an oil-extended ethylene propylene diene rubber and a non-oil-extended ethylene propylene diene rubber. From the viewpoints of achieving an excellent balance of physical properties, the ratio of the oil-extended ethylene propylene diene rubber to the non-oil-extended ethylene propylene diene rubber is preferably within a range of 5:1 to 2:1 by mass (oil-extended:non-oil-extended).

[0017] The oil for oil extension is not particularly limited as long as it is an oil that can be compounded in ethylene propylene diene rubber, but paraffin oil, naphthenic oil, etc. are preferred.

[0018] When the area ratio of the second phase is within the range of 30% to 70% within any very narrow 2.5 μm × 2.5 μm square area on the surface of the elastic layer 14, both the first and second phases are uniformly dispersed (finely dispersed) in the elastic layer 14, and differences in the coefficient of friction are unlikely to occur between locations after long-term use. As a result, this is preferable because it is more likely to prevent paper transport problems (paper jams) after long-term use.

[0019] The area ratio of the second phase is more preferably 35% or more and 65% or less, and further preferably 40% or more and 60% or less. The area ratios of the first phase and the second phase can be measured by surface analysis using a scanning probe microscope (SPM).

[0020] "Arbitrary" means "at any location." The area ratio of the first and second phases is measured in any 2.5 μm x 2.5 μm square. Specifically, as shown in Figure 2, an arbitrary cross section of the elastic layer is observed, and an arbitrary 40 x 40 μm area in that cross section is divided into 64 sections. 16 diagonally lined squares are selected, and the area ratio of the first and second phases in each 2.5 μm x 2.5 μm square is measured. The value corresponds to 14 or more squares (8.5% or more) of the selected 16 squares.

[0021] In order to uniformly disperse (finely disperse) both the first and second phases in any 2.5 μm × 2.5 μm square area, methods such as using a dispersant that improves the dispersibility of both the first and second phases, adjusting the blending ratio of the polymers of the first and second phases, or thoroughly kneading the mixture to the desired degree of dispersion can be considered.

[0022] The conditions for kneading the first phase polymer and the second phase polymer are preferably a rotation speed of 30 rpm or more and a kneading time of 5 minutes or more, more preferably a rotation speed of 40 rpm or more and a kneading time of 10 minutes or more.

[0023] The mass ratio of the first phase polymer to the second phase polymer is preferably within a range of 3:1 to 1:3 (first phase:second phase), more preferably 2.5:1 to 1:2.5 (first phase:second phase), and even more preferably 2:1 to 1:2 (first phase:second phase).

[0024] The elastic layer 14 may further contain a dispersant. Examples of dispersants include polymers having a partial structure of ethylene propylene diene rubber and a partial structure of either isoprene rubber or natural rubber, modified natural rubber, and modified isoprene rubber. Examples of modified natural rubber include epoxidized natural rubber, chlorinated natural rubber, and nitrified natural rubber (acrylonitrile natural rubber). Examples of modified isoprene rubber include epoxidized isoprene rubber, chlorinated isoprene rubber, nitrified isoprene rubber (acrylonitrile isoprene rubber), maleic acid-modified isoprene rubber, and (meth)acrylic acid-modified isoprene rubber. The elastic layer 14 may contain, as a dispersant, a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of either isoprene rubber or natural rubber. Examples of the partial structure of ethylene propylene diene rubber include an ethylene propylene structure and a structure derived from a diene. An ethylene propylene structure is particularly preferred as the partial structure of ethylene propylene diene rubber. An example of a partial structure of isoprene rubber or natural rubber is an isoprene structure. The dispersant preferably has a double bond, since it is easily fixed by crosslinking.

[0025] The content of the dispersant is preferably 1.0 part by mass or more per 100 parts by mass of the polymer of the first and second phases, from the viewpoint of achieving an excellent dispersion effect for the first and second phases. It is more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more. Furthermore, from the viewpoint of easily maintaining the physical properties of the first and second phases, it is preferably 10 parts by mass or less per 100 parts by mass of the polymer of the first and second phases. It is more preferably 7.0 parts by mass or less, and even more preferably 5.0 parts by mass or less.

[0026] The silica before the surface treatment can be produced by a known method, but is preferably produced by a dry method or a high-temperature hydrolysis method. The method for surface treatment with octylsilane is not particularly limited, and known methods can be used.

[0027] The octylsilane is not particularly limited as long as it is a silane compound containing an octylsilyl group (C8H17-), and examples thereof include n-octyltriethoxysilane and n-octyldimethylchlorosilane.

[0028] An example of hydrophobic silica having an octylsilyl group is "Aerosil R805" manufactured by EVONIK.

[0029] The content of hydrophobic silica having octylsilyl groups is 1 to 20 parts by mass per 100 parts by mass of the first and second phase polymers. If the content is less than 1 mass, wear on the surface of the elastic layer 14 cannot be suppressed after long-term use, resulting in different amounts of wear depending on the surface of the elastic layer. Furthermore, the adhesion of paper dust to the surface of the elastic layer cannot be suppressed, resulting in different coefficients of friction depending on the surface of the elastic layer, making it impossible to eliminate paper transport problems (paper jams) after long-term use. The amount of hydrophobic silica added is more preferably 2 parts by mass or more. Even more preferably, it is 3 parts by mass or more. If the content is more than 20 parts by mass, the hardness of the elastic layer increases, resulting in poor paper transport performance. It is more preferably 10 parts by mass or less. Even more preferably, it is 7 parts by mass or less.

[0030] The average particle size of the hydrophobic silica having octylsilyl groups is preferably 1 to 50 nm, more preferably 2 to 45 nm, and even more preferably 5 to 40 nm. When the average particle size is within the above range, the dispersibility of the hydrophobic silica (B) in the composition is excellent. The specific surface area (BED method) of the hydrophobic silica (B) is preferably 50 m2 / g or more, more preferably 100 to 400 m2 / g.

[0031] The hydrophobic silica having octylsilyl groups is preferably present in a higher concentration in the first phase than in the second phase. The first phase has lower abrasion resistance than the second phase and is more susceptible to abrasion, so by having a high concentration of hydrophobic silica having octylsilyl groups, the increase in hardness of the surface of the elastic layer 14 can be suppressed, thereby effectively suppressing abrasion.

[0032] In order to ensure that the hydrophobic silica having octylsilyl groups is present in a higher concentration in the first phase than in the second phase, it is possible to use a method such as first mixing the hydrophobic silica with the polymer in the first phase and then mixing it with the polymer in the second phase.

[0033] The elastic layer 14 preferably further contains a hydrocarbon-based oil. This makes it easier to obtain a dispersion effect between the first and second phases. Examples of hydrocarbon-based oils include paraffin oil. From the viewpoint of improving the dispersibility of the first and second phases, the content of the hydrocarbon-based oil is preferably 10 parts by mass or more per 100 parts by mass of the polymer of the first and second phases. It is more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. Furthermore, from the viewpoint of suppressing bleed-out of the hydrocarbon-based oil, it is preferably 50 parts by mass or less per 100 parts by mass of the polymer of the first and second phases. It is more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0034] From the viewpoint of ensuring paper feeding function, the elastic layer 14 is preferably configured so that the surface friction coefficient is in the range of 0.8 to 3.0. More preferably, it is in the range of 1.0 to 2.5. The surface of the elastic layer 14 refers to the outer peripheral surface of the elastic layer 14. The friction coefficient of the surface of the elastic layer 14 can be measured using a commercially available friction coefficient meter. The friction coefficient of the surface of the elastic layer 14 can be adjusted by the material composition of the elastic layer 14.

[0035] The elastic layer 14 is preferably configured so that its surface has a JIS-A hardness in the range of 20 to 80 degrees, and more preferably in the range of 30 to 70 degrees. The surface of the elastic layer 14 is the outer peripheral surface of the elastic layer 12b. The surface hardness of the elastic layer 14 can be adjusted by the material composition of the elastic layer 14, the thickness of the elastic layer 14, and the like. When the JIS-A hardness of the surface of the elastic layer 14 is 20 degrees or more, wear is likely to be suppressed. When the JIS-A hardness of the surface of the elastic layer 14 is 80 degrees or less, damage to the paper (such as scraping of the paper) is likely to be suppressed, and deterioration of image quality is likely to be suppressed.

[0036] The surface of the elastic layer 14 may be textured or otherwise formed to have surface irregularities. The surface irregularities of the elastic layer 14 can be formed by polishing, pattern transfer, or other methods.

[0037] The thickness of the elastic layer 14 is not particularly limited, but may be 1 to 10 mm.

[0038] The elastic layer 14 can be produced, for example, as follows: First, the shaft 12 is placed coaxially in the hollow portion of a roll molding die, an uncrosslinked rubber composition is injected, and the composition is heated and cured (crosslinked), and then the composition is demolded, or the uncrosslinked rubber composition is extruded onto the surface of the shaft 12, thereby forming the elastic layer 14 on the outer periphery of the shaft 12.

[0039] The uncrosslinked rubber composition forming the elastic layer 14 may contain a crosslinking agent, a conductive agent, a foaming agent, a surfactant, a flame retardant, a colorant, a filler, a stabilizer, a release agent, etc. as needed.

[0040] Examples of the crosslinking agent include a sulfur crosslinking agent and a peroxide crosslinking agent. These crosslinking agents may be used alone or in combination of two or more.

[0041] Examples of the sulfur crosslinking agent include conventionally known sulfur crosslinking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram vulcanization accelerators, and polymeric polysulfides.

[0042] Examples of the peroxide crosslinking agent include conventionally known peroxide crosslinking agents such as peroxyketals, dialkyl peroxides, peroxyesters, ketone peroxides, peroxydicarbonates, diacyl peroxides, and hydroperoxides.

[0043] The amount of crosslinking agent to be added is preferably within a range of 0.1 to 2 parts by mass, more preferably within a range of 0.3 to 1.8 parts by mass, and even more preferably within a range of 0.5 to 1.5 parts by mass, per 100 parts by mass of uncrosslinked rubber, from the viewpoint of preventing bleeding.

[0044] According to the paper feed roll 10 configured as described above, the elastic layer 14 has a first phase containing ethylene propylene diene rubber, a second phase containing at least one of isoprene rubber and natural rubber, and hydrophobic silica having octylsilyl groups. The amount of hydrophobic silica is 1 to 20 parts by mass per 100 parts by mass of the polymers of the first and second phases. This suppresses surface wear of the elastic layer after long-term use, so that the amount of wear does not vary depending on the area on the surface of the elastic layer. Furthermore, even if paper dust adheres to the surface of the elastic layer, the coefficient of friction is unlikely to change, so the coefficient of friction does not vary depending on the area on the surface of the elastic layer. As a result, paper transport problems (paper jams) after long-term use can be eliminated.

[0045] The paper feed roll 10 is suitable for use as a feed roll, a retard roll (separation roll), or a pickup roll (pull-in roll) in a paper feeder.

[0046] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention. [Example]

[0047] The present invention will be described in detail below using examples and comparative examples.

[0048] Example 1 <Preparation of Rubber Composition> A rubber composition was prepared by kneading 60 parts by mass of oil-extended EPDM, 20 parts by mass of non-oil-extended EPDM, 50 parts by mass of IR, 30 parts by mass of paraffin oil, 3 parts by mass of dispersant, 5 parts by mass of zinc oxide, 0.25 parts by mass of carbon black, 5 parts by mass of hydrophobic silica having octylsilyl groups, and 3 parts by mass of peroxide crosslinking agent in a kneader.

[0049] <Preparation of Elastic Layer> A core metal (diameter 8 mm) was set in a molding die, the above rubber composition was injected, and the die was heated at 160°C for 40 minutes, then cooled and demolded to form a 6 mm thick elastic layer made of a rubber elastic material on the outer periphery of the core metal.

[0050] Examples 2 to 6 A rubber composition was prepared in the same manner as in Example 1 using the compounding composition (parts by mass) shown in Table 1, and an elastic layer was formed.

[0051] Example 7 A rubber composition was prepared by kneading 60 parts by mass of oil-extended EPDM, 20 parts by mass of non-oil-extended EPDM, 30 parts by mass of paraffin oil, 3 parts by mass of dispersant, 5 parts by mass of zinc oxide, 0.25 parts by mass of carbon black, 5 parts by mass of hydrophobic silica having octylsilyl groups, and 3 parts by mass of peroxide crosslinking agent in a kneader, and then kneading 50 parts by mass of IR in the kneader.

[0052] (Comparative Examples 1 to 4) A rubber composition was prepared in the same manner as in Example 1 using the compounding composition (parts by mass) shown in Table 1, and an elastic layer was formed.

[0053] The materials used are as follows: Oil-extended EPDM: Sumitomo Chemical's "Esprene 600F" Non-oil-extended EPDM: Sumitomo Chemical's "Esprene 512F" IR: Nippon Zeon "Nipol IR2200" Paraffin oil: Idemitsu Kosan "Diana Process PS-430" Naphthenic oil: Idemitsu Kosan's "Diana Process NS-100" Dispersant: Kuraray "LIR-290" (hydrogenated isoprene) Zinc oxide: Reagent Carbon black: Cabot "Show Black MAF-G" Silica (i): EVONIK Aerosil R805 (hydrophobic / octylsilyl group / specific surface area by BET method: 125-175 m2 / g) Silica (II): EVONIK Aerosil RX200 (hydrophobic / trimethylsilyl group / specific surface area by BET method: 115-165 m2 / g) Silica (III): EVONIK Aerosil 200 (hydrophilic / BET specific surface area: 175-225 m2 / g) Peroxide crosslinking agent: NOF's "Perkmyl D"

[0054] The area ratio of the elastic layer of the fabricated paper feed roll was measured, and the initial friction coefficient of the elastic layer was also measured. An actual machine evaluation was also performed.

[0055] (area ratio) Measurements were made using a scanning probe microscope (Shimadzu Corporation, "SPM-9700"), as shown in Figure 2. An arbitrary surface of the elastic layer was observed, and an arbitrary 20 × 20 μm area on that surface was divided into 64 sections, and 16 squares arranged diagonally with diagonal lines were selected. The area proportions of the first and second phases in each 2.5 μm × 2.5 μm square were measured, and the values ​​were determined to be those that applied to 14 or more of the 16 squares (8.5% or more). Measurement locations: 4 locations around the left, center, and right ends of the elastic layer (12 locations in total) Cantilever: SI-DF40 Scanning range: 5.0000μm Scanning speed: 1.00Hz

[0056] (coefficient of friction) A 60mm x 210mm sheet of paper (Fuji Xerox P paper) connected to a load cell was sandwiched between the paper feed roll and a polytetrafluoroethylene plate. A vertical load W (W = 250gf) was applied to the rotation axis of the paper feed roll, pressing the paper feed roll against the polytetrafluoroethylene plate. The paper feed roll was then rotated at a peripheral speed of 300mm / s under conditions of 23°C temperature and 55% humidity. The paper feed force F (gf) generated by the paper 24 was measured with a load cell before and after the paper feed. The friction coefficient μ was calculated using the following formula 1 from F (gf) and the load W (W = 250gf). The initial friction coefficient was evaluated as "〇〇" for 1.5 or greater, "〇" for 1.0 or greater but less than 1.5, and "×" for less than 1.0. (Equation 1) μ=F(gf) / W(gf)

[0057] (Actual machine evaluation) The paper feed roll was installed in a commercially available copier with an FRR paper feed system, and paper feed performance was evaluated. Commercially available PPC paper was used, and 300,000 sheets (300K sheets) were fed through, and the number of paper jams was measured. A paper jam occurring once or less was marked "XX", a paper jam occurring 2 to 5 times was marked "XX", a paper jam occurring 6 to 10 times was marked "〇", and a paper jam occurring 11 times was marked "×". Furthermore, if 11 paper jams occurred, the durability evaluation was discontinued.

[0058] (Confirm uneven distribution) Measurements were made using a scanning probe microscope (Shimadzu Corporation, "SPM-9700"). As shown in Figure 2, the uneven distribution of silica was confirmed by observing any surface of the elastic layer and measuring the hardness. When the proportion of silica in the first phase and the proportion of silica in the second phase are the same, this corresponds to no uneven distribution, and when more silica is present in either phase, this corresponds to the presence of uneven distribution.

[0059] [Table 1]

[0060] [Table 2]

[0061] Comparative Examples 1, 3, and 4 do not contain hydrophobic silica having octylsilyl groups, so wear of the first phase is likely to occur, and the decrease in the coefficient of friction due to paper dust adhesion cannot be suppressed, resulting in poor performance in actual machine evaluation after long-term use. Comparative Example 2 contains more than 20 parts by mass of hydrophobic silica having octylsilyl groups, so the specified hardness was not achieved and evaluation was not possible. Comparative Example 5 uses only EPDM as the polymer in the elastic layer. As a result, the initial coefficient of friction on the surface of the elastic layer is low, and wear of the surface layer of the elastic layer is likely to occur, resulting in poor performance in actual machine evaluation after long-term use.

[0062] In contrast, in the working examples, the polymer in the elastic layer was composed of EPDM and IR, and the hydrophobic silica with octylsilyl groups was within the appropriate range, and in actual machine evaluation, even after long-term use of 300,000 sheets, paper was rarely unable to be transported straight, and transport problems (paper jams) hardly occurred. In particular, when the hydrophobic silica with octylsilyl groups was unevenly distributed in the first phase and the area ratio of the second phase was within a narrow range of 30 to 70%, the actual machine evaluation also showed an excellent effect in suppressing transport problems (paper jams).

[0063] Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications are possible within the scope of the invention. [Explanation of symbols]

[0064] 10 Paper feed roll 12 shaft body 14 Elastic layer

Claims

1. A paper feed roll comprising a shaft body and an elastic layer formed on the outer periphery of the shaft body, the elastic layer is a layer that appears on the surface of the paper feed roll and contains a polymer and hydrophobic silica having an octylsilyl group; the content of the hydrophobic silica is 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the polymer, The elastic layer has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber.

2. 2. The paper feed roll according to claim 1, wherein the area ratio of the second phase is in the range of 30 to 70% within any 2.5 μm×2.5 μm square area of ​​the elastic layer.

3. 3. The paper feed roll according to claim 1, wherein the elastic layer further contains a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of either isoprene rubber or natural rubber.

4. The paper feed roll according to claim 1 , wherein a part of the structure of the ethylene propylene diene rubber is an ethylene propylene structure.

5. The paper feed roll according to any one of claims 1 to 4, wherein the ethylene propylene diene rubber contains both oil-extended ethylene propylene diene rubber and non-oil-extended ethylene propylene diene rubber.

6. 5. The paper feed roll of claim 1, wherein the hydrophobic silica is present in a higher concentration in the first phase than in the second phase.

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