paper feed roller

Abstract

A paper feed roller is provided that, when the elastomer layer is composed of two or more phases, suppresses surface unevenness of the elastomer layer and can suppress poor feeding even during long-term use. The paper feed roller 10 includes a shaft 12 and an elastomer layer 14 formed on the outer peripheral surface of the shaft 12. The elastomer layer 14 has a first phase comprising ethylene propylene diene rubber and a second phase comprising isoprene rubber and natural rubber or more thereof. Within any 2.5 μm × 2.5 μm square area of ​​the elastomer layer 14, the area ratio of the second phase is in the range of 30% or more and 70% or less.

Description

Technical Field

[0001] This invention relates to paper feed rollers suitable for use in electrophotographic devices such as copiers, printers, and fax machines that employ electrophotographic methods. Background Technology

[0002] As a paper feed roller, there are known paper feed rollers that have an elastomer layer made of an elastic material such as a rubber crosslinker on the outer peripheral surface of an equiaxed core. There are also known paper feed rollers that use ethylene propylene diene rubber, isoprene rubber, styrene butadiene rubber, etc., as the elastic material of the elastomer layer (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-196428 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] When the elastic material of the elastomer layer is composed of two or more polymer components, the elastomer layer is mostly composed of two or more phases with different polymer compositions. Due to the different polymer compositions, the wear amount and paper dust adhesion amount of each phase are different. As a result, after long-term use, the difference in the coefficient of friction of each phase increases, and therefore the coefficient of friction on the surface of the elastomer layer easily becomes uneven. If the coefficient of friction on the surface of the elastomer layer is uneven, the paper cannot be fed in a straight line, resulting in poor feeding (paper jam) problems.

[0008] The problem to be solved by the present invention is to provide a paper feed roller that, when the elastomer layer is composed of two or more phases, suppresses the surface unevenness of the elastomer layer and can suppress poor feeding even during long-term use.

[0009] means for solving problems

[0010] The paper feed roller of the present invention comprises a shaft and an elastomer layer formed on the outer peripheral surface of the shaft. The elastomer layer has a first phase comprising ethylene propylene diene rubber and a second phase comprising isoprene rubber and natural rubber or more thereof. In any 2.5 μm × 2.5 μm square area of ​​the elastomer layer, the area ratio of the second phase is in the range of 30% or more and 70% or less.

[0011] Preferably, the elastomer layer further comprises a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of isoprene rubber and natural rubber. Preferably, the partial structure of the ethylene propylene diene rubber is an ethylene propylene structure. Preferably, the elastomer layer contains a hydrocarbon oil. Preferably, the ethylene propylene diene rubber comprises both oil-extended ethylene propylene diene rubber and non-oil-extended ethylene propylene diene rubber.

[0012] Invention Effects

[0013] According to the paper feed roller of the present invention, a shaft body and an elastomer layer formed on the outer peripheral surface of the shaft body are provided. The elastomer layer has a first phase comprising ethylene propylene diene rubber and a second phase comprising isoprene rubber and natural rubber or more thereof. In any 2.5 μm × 2.5 μm square range of the elastomer layer, the area ratio of the second phase is in the range of 30% or more and 70% or less. Therefore, when the elastomer layer is composed of two or more phases, the surface unevenness of the elastomer layer can be suppressed, and poor feeding can be suppressed even during long-term use.

[0014] If the elastomer layer further contains a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of isoprene rubber and natural rubber, the dispersibility of the second phase relative to the first phase is further improved. Consequently, the coefficient of friction on the surface of the elastomer layer becomes more uniform, improving the ability to suppress poor transport during long-term use.

[0015] Furthermore, if a portion of the structure of the ethylene propylene diene rubber is an ethylene propylene structure, the dispersibility of the second phase relative to the first phase is further improved. Consequently, the coefficient of friction on the surface of the elastomer layer becomes more uniform, improving the effectiveness in suppressing poor transport during long-term use.

[0016] Furthermore, if the elastomer layer contains hydrocarbon-based oil, the compatibility between the first phase and the second phase is improved, and the dispersibility of the second phase relative to the first phase is improved. As a result, the coefficient of friction on the surface of the elastomer layer becomes more uniform, improving the effectiveness in suppressing poor transport during long-term use.

[0017] Furthermore, if the ethylene propylene diene rubber contains both oil-extended and non-oil-extended ethylene propylene diene rubber, sufficient shearing is applied during rubber compounding, thus improving the dispersibility of the second phase relative to the first phase. Consequently, the coefficient of friction on the surface of the elastomer layer becomes more uniform, improving the ability to suppress poor transport during long-term use. Attached Figure Description

[0018] Figure 1(a) is a schematic diagram of the appearance of the paper feed roller according to one embodiment of the present invention. Figure 1 (b) in the figure is its sectional view along line AA.

[0019] Figure 2 This is a schematic diagram illustrating a method for measuring the area ratio of the first and second phases in an elastomer layer. Detailed Implementation

[0020] The paper feeding rollers involved in this invention will be described in detail. Figure 1 (a) in the figure is a schematic diagram of the appearance of the paper feed roller according to one embodiment of the present invention. Figure 1 (b) in the figure is its sectional view along line AA.

[0021] One embodiment of the present invention includes a paper feed roller 10 comprising a shaft 12 and an elastomer layer 14 formed on the outer peripheral surface of the shaft 12. The elastomer layer 14 is a layer (base layer) that forms the substrate of the paper feed roller 10. The elastomer layer 14 is a layer that appears on the surface of the paper feed roller 10.

[0022] The shaft 12 can be a solid or hollow (cylindrical) body made of metal or resin. Examples of metal materials include iron, stainless steel, and aluminum. The elastomer layer 14 can also be bonded to the shaft 12 via an adhesive layer (primer layer). The adhesive and primer can be made conductive as needed.

[0023] The elastomer layer 14 has a first phase comprising ethylene propylene diene rubber and a second phase comprising isoprene rubber and natural rubber, wherein the area ratio of the second phase is between 30% and 70% within any 2.5 μm × 2.5 μm square area.

[0024] In the elastomer layer 14, ethylene propylene diene rubber (EPDM) is suitable for setting the hardness of the elastomer layer 14 to a desired range. One or more of isoprene rubber (IR) and natural rubber (NR) are materials with a higher coefficient of friction than ethylene propylene diene rubber, which is suitable for improving the paper feeding properties of ethylene propylene diene rubber, which has a relatively low coefficient of friction. Furthermore, the first and second phases are uniformly dispersed (micro-dispersed) in the elastomer layer 14 in a very narrow range of 2.5 μm × 2.5 μm square, where the area ratio of the second phase is between 30% and 70%. Therefore, the surface coefficient of friction of the elastomer layer does not vary depending on the location, becoming uniform, and poor feeding can be suppressed even during long-term use.

[0025] Furthermore, the area ratio of the second phase is more preferably 35% or more and 65% or less, and even more preferably 40% or more and 60% or less. The area ratio of the first phase to the second phase can be determined by surface analysis using a scanning probe microscope (SPM).

[0026] "Any" means that this applies to any location. The area ratio of the first and second phases is arbitrary. See the 2.5μm × 2.5μm square for the area ratio of the first and second phases. Specifically, for example... Figure 2 As shown, an arbitrary surface of the elastomer layer was observed. This surface was divided into 64 sections of any 20×20μm area. Sixteen squares, drawn as diagonal lines and arranged along the inclined direction, were selected. The area ratio of the first and second phases within each 2.5μm×2.5μm square was measured. Values ​​meeting the criteria were found in at least 14 of the selected 16 squares (over 8.5%). Scanning probe microscopy (SPM) was used to image four locations (a total of 12 locations) circumferentially at the left, central, and right ends of the elastomer layer along the axial direction.

[0027] To achieve uniform dispersion (micro-dispersion) of the first and second phases in any 2.5 μm × 2.5 μm square, methods such as adjusting the blending ratio of the first and second phase polymers, thoroughly mixing to the desired dispersion, and using dispersants that improve the dispersibility of the first and second phases can be considered.

[0028] The ratio of the polymer in the first phase to the polymer in the second phase, by mass, is preferably in the range of 3:1 to 1:3. More preferably, it is in the range of 2.5:1 to 1:2.5, and even more preferably, it is in the range of 2:1 to 1:2.

[0029] For the mixing conditions of the polymer as the first phase and the polymer as the second phase, in order to achieve the above-mentioned area ratio, a mixing speed of 30 rpm or more and a mixing time of 5 minutes or more are preferred. More preferably, a mixing speed of 40 rpm or more and a mixing time of 10 minutes or more are preferred.

[0030] Ethylene propylene diene rubber is produced by copolymerizing a non-conjugated diene as a third component with ethylene propylene rubber (EPM), a copolymer of ethylene and propylene. Ethylene propylene diene rubber possesses a non-conjugated diene structure derived from the ethylene-propylene structure within its molecular structure. Examples of non-conjugated dienes used in ethylene propylene diene rubber include ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), and dicyclopentadiene (DCPD).

[0031] The ethylene propylene diene rubber can be either oil-extended or non-oil-extended. Alternatively, it may include both oil-extended and non-oil-extended ethylene propylene diene rubber. From the viewpoints of facilitating sufficient shearing during rubber compounding and improving the dispersibility of the second phase relative to the first phase, it is preferable to include both oil-extended and non-oil-extended ethylene propylene diene rubber. From the viewpoint of facilitating sufficient shearing during rubber compounding, the ratio of oil-extended to non-oil-extended ethylene propylene diene rubber, by mass, is preferably in the range of 5:1 to 2:1. More preferably, it is in the range of 4:1 to 2:1.

[0032] As for the oil used for filling, any oil that can be used with ethylene propylene diene rubber is acceptable, with no particular limitation. Paraffinic oils, cycloalkanes, etc. are preferred.

[0033] Examples of dispersants include polymers having partial structures of ethylene propylene diene rubber and partial structures of isoprene rubber and 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 elastomer layer 14 may contain a polymer having partial structures of ethylene propylene diene rubber and partial structures of isoprene rubber and natural rubber as a dispersant. Examples of partial structures of ethylene propylene diene rubber include ethylene propylene structures and diene-derived structures. Ethylene propylene structures are particularly preferred as partial structures of ethylene propylene diene rubber. Examples of partial structures of isoprene rubber and natural rubber include isoprene structures. From the perspective of easy fixation through cross-linking, dispersants preferably have double bonds.

[0034] Polymers having partial structures of ethylene propylene diene rubber and partial structures of either isoprene rubber or natural rubber can be exemplified as block copolymers of ethylene propylene diene rubber and isoprene rubber, block copolymers of ethylene propylene diene rubber and natural rubber, and hydrogenated isoprene rubber formed by hydrogenating a portion of isoprene rubber. Examples of hydrogenated isoprene rubber include, for instance, "LIR-290" manufactured by KURARAY.

[0035] From the viewpoint of excellent dispersion effect on both the first and second phases, the content of the dispersant is preferably 1.0 parts by mass or more relative to 100 parts by mass of the polymer in both the first and second phases. More preferably, it is 1.5 parts by mass or more, and even more preferably, it is 2.0 parts by mass or more. Furthermore, from the viewpoint of easily maintaining the physical properties of both the first and second phases, it is preferably 10 parts by mass or less relative to 100 parts by mass of the polymer in both the first and second phases. More preferably, it is 7.0 parts by mass or less, and even more preferably, it is 5.0 parts by mass or less.

[0036] The elastomer layer 14 preferably also contains a hydrocarbon-based oil. This facilitates the dispersion of both the first and second phases. Examples of hydrocarbon-based oils include paraffinic oils. 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 relative to 100 parts by mass of the polymer of the first and second phases. More preferably, it is 15 parts by mass or more, and even more preferably, 20 parts by mass or more. Furthermore, from the viewpoint of suppressing the exudation of the hydrocarbon-based oil, it is preferably 50 parts by mass or less relative to 100 parts by mass of the polymer of the first and second phases. More preferably, it is 45 parts by mass or less, and even more preferably, 40 parts by mass or less.

[0037] From the viewpoint of ensuring paper feeding function, the elastomer layer 14 is preferably configured such that its 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 elastomer layer 14 refers to the outer peripheral surface of the elastomer layer 14. The surface friction coefficient of the elastomer layer 14 can be measured using a commercially available friction coefficient meter. The surface friction coefficient of the elastomer layer 14 can be adjusted by the material composition of the elastomer layer 14.

[0038] The elastomer layer 14 is preferably configured such that its surface JIS-A hardness is in the range of 20 to 80 degrees. More preferably, it is in the range of 30 to 70 degrees. The surface of the elastomer layer 14 refers to its outer peripheral surface. The surface hardness of the elastomer layer 14 can be adjusted by the material composition of the elastomer layer 14, the thickness of the elastomer layer 14, etc. If the surface JIS-A hardness of the elastomer layer 14 is 20 degrees or higher, wear is easily suppressed. If the surface JIS-A hardness of the elastomer layer 14 is 80 degrees or lower, damage to the paper (paper scratches, etc.) is easily suppressed, and image quality deterioration is easily suppressed.

[0039] Surface irregularities, such as texturing, can also be applied to the surface of the elastomer layer 14. Surface irregularities of the elastomer layer 14 can be formed by methods such as grinding or mold transfer.

[0040] The thickness of the elastomer layer 14 is not particularly limited and can be 1 to 10 mm.

[0041] The elastomer layer 14 can be manufactured, for example, in the following manner. First, the shaft 12 is coaxially disposed in the hollow part of the roll forming mold, an uncrosslinked rubber composition is injected, and after heating and curing (crosslinking), it is demolded, or the uncrosslinked rubber composition is extruded on the surface of the shaft 12, thereby forming the elastomer layer 14 on the outer periphery of the shaft 12.

[0042] The uncrosslinked rubber composition forming the elastomer layer 14 may contain crosslinking agents, conductive agents, foaming agents, surfactants, flame retardants, colorants, fillers, stabilizers, release agents, etc., as needed.

[0043] Examples of crosslinking agents include sulfur crosslinking agents and peroxide crosslinking agents. These crosslinking agents can be used alone or in combination of two or more.

[0044] As sulfur crosslinking agents, examples include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram-based sulfurization accelerators, and high-molecular-weight polysulfides, which are all previously known sulfur crosslinking agents.

[0045] Examples of peroxide crosslinking agents include peroxide ketals, dialkyl peroxides, peroxide esters, peroxide ketones, peroxide dicarbonates, diacyl peroxides, and hydroperoxides, which are all known peroxide crosslinking agents.

[0046] From the viewpoint of minimizing leakage, the amount of crosslinking agent used is preferably in the range of 0.1 to 4 parts by mass relative to 100 parts by mass of uncrosslinked rubber, more preferably in the range of 0.3 to 3 parts by mass, and even more preferably in the range of 0.5 to 2.5 parts by mass.

[0047] The paper feed roller 10 constructed as described above has an elastomer layer 14 comprising a first phase containing ethylene propylene diene rubber and a second phase containing one or more of isoprene rubber and natural rubber. Within any 2.5 μm × 2.5 μm square area, the area ratio of the second phase is between 30% and 70%. Therefore, the first and second phases are uniformly dispersed (micro-dispersed) in the elastomer layer 14, preventing variations in the surface friction coefficient of the elastomer layer depending on the location. Even with differences in polymer composition, wear amounts of each phase, and paper dust adhesion, the surface friction coefficient of the elastomer layer remains uniform. This eliminates the problem of poor paper feeding (paper jams) caused by the inability to feed paper straight after prolonged use, and suppresses poor feeding even during long-term use.

[0048] The paper feed roller 10 is suitable for the paper feed roller, the deflector roller (separation roller), and the pickup roller (introducer roller) in a paper feeding device.

[0049] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0050] Example

[0051] The present invention will now be described in detail using examples and comparative examples.

[0052] (Example 1)

[0053] <Preparation of Rubber Compositions>

[0054] A rubber composition is prepared by kneading 60 parts by weight of oil-extended EPDM, 20 parts by weight of non-oil-extended EPDM, 50 parts by weight of IR, 30 parts by weight of paraffinic oil, 3 parts by weight of dispersant, 5 parts by weight of zinc oxide, 0.25 parts by weight of carbon black, 5 parts by weight of silica and 3 parts by weight of peroxide crosslinking agent in a kneader.

[0055] <Fabrication of Elastomer Layers>

[0056] A mandrel (8 mm in diameter) is placed in a molding die, the above-mentioned rubber composition is injected, and after heating at 160°C for 40 minutes, it is cooled and demolded to form an elastomer layer with a thickness of 6 mm made of rubber elastomer on the outer periphery of the mandrel.

[0057] (Examples 2-7)

[0058] A rubber composition was prepared in the same manner as in Example 1, using the formulation (parts by mass) shown in Table 1, to form an elastomer layer.

[0059] (Comparative Examples 1-2)

[0060] A rubber composition was prepared in the same manner as in Example 1, using the formulation (parts by mass) shown in Table 1, to form an elastomer layer.

[0061] The materials used are as follows.

[0062] • Oil-extended EPDM: Sumitomo Chemical's "ESPRENE 600F"

[0063] • Non-oil-extended EPDM: "ESPRENE 512F" manufactured by Sumitomo Chemical.

[0064] • IR: Nipol IR2200 manufactured by Zeon Corporation of Japan

[0065] ·NR: RSS#3

[0066] • Paraffinic oil: "Diana Process PS-430" manufactured by Idemitsu Kosan

[0067] • Naphthenic oil: "Diana Process NS-100" manufactured by Idemitsu Kosan

[0068] • Dispersant: "LIR-290" (hydrogenated isoprene) manufactured by KURARAY

[0069] Zinc oxide: reagent

[0070] • Carbon black: "SHO BLACK MAF-G" manufactured by Cabot

[0071] • Silica: Tosoh's "Nipsil VN3" silica

[0072] • Peroxide crosslinking agent: "PERCUMYL D" manufactured by Nippon Oil.

[0073] The area ratio of the elastomer layer was measured for the manufactured paper feed roller. Additionally, the initial coefficient of friction of the elastomer layer was measured. Furthermore, a practical evaluation was conducted.

[0074] (Area ratio)

[0075] Measurements were performed using a scanning probe microscope (Shimadzu SPM-9700). For example... Figure 2 As shown, observe any surface of the elastomer layer, divide any 20×20μm area on the surface into 64 parts, select 16 squares arranged along the inclined direction as diagonal lines, and measure the area ratio of the first phase and the second phase in each 2.5μm×2.5μm square. Values ​​with more than 14 squares (more than 8.5%) out of the 16 squares are considered to be in compliance.

[0076] • Measurement sites: Four locations circumferentially at each of the left, central, and right ends of the elastomer layer (a total of 12 locations).

[0077] • Cantilever: SI-DF40

[0078] • Scan range: 5.0000μm

[0079] • Scan speed: 1.00Hz

[0080] (Coefficient of friction)

[0081] A 60mm × 210mm sheet of paper (Fuji Xerox P-paper) connected to a force sensor is held between the paper feed roller and a PTFE plate. A vertical load W (W = 250gf) is applied to the rotation axis of the paper feed roller, pressing the paper feed roller against the PTFE plate. Then, under conditions of 23°C and 55% humidity, the paper feed roller is rotated at a circumferential speed of 300mm / s. Before and after paper feeding, the conveying force F (gf) of the generated paper 24 is measured using a force sensor. Based on F (gf) and the load W (W = 250gf), the coefficient of friction μ is calculated using the following mathematical formula 1. An initial coefficient of friction of 1.5 or higher is rated as "◎", 1.0 or higher but less than 1.5 is rated as "〇", and less than 1.0 is rated as "×".

[0082] (Mathematical Formula 1)

[0083] μ=F(gf) / W(gf)

[0084] (Real-world performance evaluation)

[0085] The paper feed rollers were installed in a commercially available copier with an FRR (Free-Rate Response) paper feeding system, and paper feeding performance was evaluated. Commercially available PPC paper was used, and 300,000 sheets (300,000 sheets) were fed to measure the number of paper jams. Paper jams occurring once or less were rated as "○○", two to five times as "○", six to ten times as "×", and eleven times as "××". Furthermore, the durability evaluation was discontinued if eleven paper jams occurred.

[0086]

[0087] In Comparative Example 1, the polymer of the elastomer layer was composed of EPDM and IR, but the EPDM was only unoil-filled EPDM. Within a very narrow area of ​​2.5 μm × 2.5 μm square, areas without a second phase or areas containing only a second phase were observed, so the surface friction coefficient of the elastomer layer could not be considered uniform. Moreover, in actual machine evaluation, during long-term use with a paper throughput of 300,000 sheets, there were many instances where the paper could not be fed straight, resulting in multiple paper feeding failures (paper jams). In Comparative Example 2, the polymer of the elastomer layer was also composed of EPDM and IR, but the EPDM was only oil-filled EPDM. Within a very narrow area of ​​2.5 μm × 2.5 μm square, areas without a second phase or areas containing only a second phase were observed, so the surface friction coefficient of the elastomer layer could not be considered uniform. Moreover, in actual machine evaluation, during long-term use with a paper throughput of 300,000 sheets, there were many instances where the paper could not be fed straight, resulting in multiple paper feeding failures (paper jams).

[0088] In contrast, in the embodiments, the polymer of the elastomer layer is composed of EPDM and IR. Furthermore, within a very narrow range of 2.5 μm × 2.5 μm square, no locations were observed with or without a second phase; the area ratio of the second phase converged within an appropriate range, resulting in a uniform coefficient of friction on the surface of the elastomer layer. Moreover, in practical evaluations, even after long-term use of 300,000 sheets, there were almost no instances of paper not being fed straight, and paper jams were virtually nonexistent. In particular, in the example using a dispersant, the range of the second phase area ratio converged even narrower, the coefficient of friction on the surface of the elastomer layer was more uniform, and the effect of suppressing paper jams in practical evaluations was also superior.

[0089] The embodiments and examples of the present invention have been described above, but the present invention is not limited to any of the above embodiments and examples, and various changes can be made without departing from the spirit of the present invention.

[0090] Explanation of reference numerals in the attached figures

[0091] 10: Paper feeding roller;

[0092] 12: Shaft;

[0093] 14: Elastomer layer.

Claims

1. A paper feeding roller, wherein, The paper feed roller has a shaft and an elastomer layer formed on the outer peripheral surface of the shaft. The elastomeric layer is a layer that appears on the surface. The elastomer layer has a first phase comprising ethylene propylene diene rubber and a second phase comprising one or more of isoprene rubber and natural rubber. The elastomer layer also contains a polymer having a partial structure of ethylene propylene diene rubber and a partial structure of isoprene rubber and natural rubber. Within any 2.5μm × 2.5μm square area of ​​the elastomer layer, where the area ratio of the second phase is between 45% and 55%, the coefficient of friction of the surface of the elastomer layer is 1.0 to 2.

5.

2. The paper feed roller according to claim 1, wherein The ethylene propylene diene rubber has a partial structure of ethylene propylene.

3. The paper feed roller according to claim 1 or 2, wherein The elastomer layer contains hydrocarbon oil.

4. The paper feed roller according to claim 1 or 2, wherein The ethylene propylene diene rubber includes both oil-extended ethylene propylene diene rubber and non-oil-extended ethylene propylene diene rubber.

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