Paper feed roll

Abstract

To provide a paper feed roll in which when an elastic body payer is configured from two or more layers, nonuniformity of a surface of the elastic body layer is suppressed, and transport failures are reduced even during long-term use.SOLUTION: A paper feed roll 10 comprises a shaft body 12, and an elastic body layer 14 which is formed on an outer peripheral surface of the shaft body 12. The elastic body layer 14 has a first phase containing ethylene-propylene-diene rubber and a second phase containing any one of isoprene rubber and natural rubber. In any range of 2.5 μm×2.5 μm square of the elastic body layer 14, the area ratio of the second phase falls within a range of 30% or more and 70% or less.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 that the present invention aims to solve is to provide a paper feed roll that can suppress unevenness in the surface of the elastic layer and prevent transport problems even during long-term use when the elastic layer is composed of two or more layers. [Means for solving the problem]

[0006] The paper feed roll of the present invention comprises a shaft body and an elastic layer formed on the outer surface of the shaft body, wherein 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, and within any 2.5 μm x 2.5 μm square area of ​​the elastic layer, the area ratio of the second phase is in the range of 30% to 70%.

[0007] 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. The partial structure of the ethylene propylene diene rubber is preferably an ethylene propylene structure. The elastic layer preferably 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. [Effects of the Invention]

[0008] The paper feed roll according to the present invention comprises a shaft body and an elastic layer formed on the outer peripheral surface of the shaft body, 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, and within any 2.5 μm x 2.5 μm square area of ​​the elastic layer, the area ratio of the second phase is in the range of 30% to 70%. Therefore, when the elastic layer is composed of two or more phases, unevenness in the surface of the elastic layer is suppressed, thereby suppressing poor conveying even during long-term use.

[0009] If 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, the dispersibility of the second phase in the first phase is further improved, which makes the coefficient of friction on the surface of the elastic layer more uniform and improves the effect of suppressing conveyance defects during long-term use.

[0010] When a portion of the structure of the ethylene propylene diene rubber is an ethylene propylene structure, the dispersibility of the second phase in the first phase is further improved, which makes the coefficient of friction on the surface of the elastic layer more uniform and improves the effect of suppressing conveyance defects during long-term use.

[0011] Furthermore, when the elastomer layer contains a hydrocarbon oil, the compatibility between the first phase and the second phase increases, improving the dispersibility of the second phase in the first phase, which in turn makes the coefficient of friction on the surface of the elastomer layer more uniform and improves the effect of suppressing conveyance defects during long-term use.

[0012] Furthermore, when the ethylene propylene diene rubber contains both oil-extended and non-oil-extended ethylene propylene diene rubbers, sufficient shear is applied during the rubber kneading process, improving the dispersibility of the second phase in the first phase, which in turn makes the coefficient of friction on the surface of the elastic layer more uniform and improves the effect of suppressing conveyance problems during long-term use. [Brief explanation of the drawings]

[0013] [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

[0014] 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.

[0015] 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.

[0016] 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.

[0017] The elastic layer 14 has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber, and the area ratio of the second phase within any 2.5 μm × 2.5 μm square area is in the range of 30% to 70%.

[0018] In the elastic layer 14, ethylene propylene diene rubber (EPDM) is suitable for achieving a desired hardness range for the elastic layer 14. At least one of isoprene rubber (IR) and natural rubber (NR) has a higher coefficient of friction than ethylene propylene diene rubber and is suitable for improving the paper feed performance of ethylene propylene diene rubber, which has a relatively low coefficient of friction. Furthermore, both the first and second phases are uniformly dispersed (finely dispersed) in the elastic layer 14 so that 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. This ensures that the coefficient of friction on the surface of the elastic layer is uniform and not uneven, thereby preventing poor paper feed even during 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 proportions of the first and second phases are measured in any 2.5 μm x 2.5 μm square. Specifically, as shown in Figure 2, any surface of the elastic layer is observed, and any 20 x 20 μm area on that surface is divided into 64 sections. 16 diagonally lined squares are selected, and the area proportions of the first and second phases in each 2.5 μm x 2.5 μm square are measured. The values ​​are those that apply to 14 or more of the 16 selected squares (8.5% or more). Photographs using a scanning probe microscope (SPM) are taken at four locations in the circumferential direction (12 locations in total) at the left end, center, and right end of the elastic layer in the axial direction.

[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 adjusting the blending ratio of the first and second phase polymers, thoroughly kneading to the desired degree of dispersion, or using a dispersant that improves the dispersibility of both the first and second phases can be considered.

[0022] 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).

[0023] The kneading conditions for 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, and more preferably a rotation speed of 40 rpm or more and a kneading time of 10 minutes or more, to achieve the above area ratio.

[0024] 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).

[0025] 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 a sufficient shear force during the rubber kneading process 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 easily applying a sufficient shear force during the rubber kneading process, it is preferable that the ratio of the oil-extended ethylene propylene diene rubber to the non-oil-extended ethylene propylene diene rubber is in the range of 5:1 to 2:1 by mass. More preferably, the oil-extended ethylene propylene diene rubber is in the range of 4:1 to 2:1 by mass.

[0026] 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, naphthene oil, etc. are preferred.

[0027] 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 preferably contains, 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 a partial structure of ethylene propylene diene rubber. Examples of the partial structure of isoprene rubber and natural rubber include an isoprene structure. The dispersant preferably has a double bond, since it is easily fixed by crosslinking.

[0028] Examples of polymers having a partial structure of ethylene propylene diene rubber and a partial structure of either isoprene rubber or natural rubber include block copolymers of ethylene propylene diene rubber and isoprene rubber, block copolymers of ethylene propylene diene rubber and natural rubber, and hydrogenated isoprene rubber obtained by partially hydrogenating isoprene rubber. An example of hydrogenated isoprene rubber is "LIR-290" manufactured by Kuraray.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 refers to the outer peripheral surface of the elastic layer 14. 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.

[0033] 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.

[0034] The thickness of the elastic layer 14 is not particularly limited, but may be 1 to 10 mm.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] According to the paper feed roll 10 having the above configuration, the elastic layer 14 has a first phase containing ethylene propylene diene rubber and a second phase containing at least one of isoprene rubber and natural rubber, and the area ratio of the second phase is between 30% and 70% within any 2.5 μm × 2.5 μm square area. Therefore, both the first and second phases are uniformly dispersed (finely dispersed) in the elastic layer 14, and the coefficient of friction on the surface of the elastic layer is uniform rather than uneven depending on the location. Even if the polymer components are different and the amount of wear and paper dust adhesion differs between phases, the coefficient of friction on the surface of the elastic layer does not become uneven. This eliminates the problem of paper not being able to be transported straight after long-term use, which causes transport problems (paper jams), and reduces transport problems even during long-term use.

[0042] 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.

[0043] 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]

[0044] The present invention will be described in detail below using examples and comparative examples.

[0045] 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 silica, and 3 parts by mass of a peroxide crosslinking agent in a kneader.

[0046] <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.

[0047] Examples 2 to 7 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.

[0048] (Comparative Examples 1 and 2) 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.

[0049] 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" ·NR:RSS#3 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: Tosoh Silica "Nipsil VN3" Peroxide crosslinking agent: NOF's "Perkmyl D"

[0050] 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.

[0051] (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

[0052] (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). An initial friction coefficient of 1.5 or greater was designated "◎", a value of 1.0 or greater but less than 1.5 was designated "〇", and a value less than 1.0 was designated "×". (Equation 1) μ=F(gf) / W(gf)

[0053] (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 "○", a paper jam occurring 6 to 10 times was marked "×", and a paper jam occurring 11 times was marked "XX". Furthermore, if 11 paper jams occurred, the durability evaluation was discontinued.

[0054] [Table 1]

[0055] In Comparative Example 1, the polymer of the elastic layer was composed of EPDM and IR, but the EPDM was exclusively non-oil-extended EPDM. Within a very narrow area of ​​2.5 μm × 2.5 μm, areas where the second phase was absent or only the second phase were observed, resulting in a non-uniform coefficient of friction on the surface of the elastic layer. Furthermore, in an actual machine evaluation, paper was frequently unable to be conveyed straight during long-term use with a paper feed rate of 300,000 sheets, resulting in numerous paper feed failures (paper jams). In Comparative Example 2, the polymer of the elastic layer was also composed of EPDM and IR, but the EPDM was exclusively oil-extended EPDM. Within a very narrow area of ​​2.5 μm × 2.5 μm, areas where the second phase was absent or only the second phase were observed, resulting in a non-uniform coefficient of friction on the surface of the elastic layer. Furthermore, in an actual machine evaluation, paper was frequently unable to be conveyed straight during long-term use with a paper feed rate of 300,000 sheets, resulting in numerous paper feed failures (paper jams).

[0056] In contrast, in the examples, the polymer of the elastic layer was composed of EPDM and IR. Furthermore, within a very narrow area of ​​2.5 μm x 2.5 μm, no areas lacking the second phase or containing only the second phase were observed. The area ratio of the second phase was within the appropriate range, and the coefficient of friction on the surface of the elastic layer was uniform. Furthermore, in actual machine evaluations, even after long-term use of 300,000 sheets, paper was rarely unable to be transported straight, and transport problems (paper jams) rarely occurred. In particular, in the examples using a dispersant, the area ratio of the second phase was even narrower, the coefficient of friction on the surface of the elastic layer was even more uniform, and the actual machine evaluation also demonstrated superior effectiveness in suppressing transport problems (paper jams).

[0057] 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]

[0058] 10 Paper feed roll 12 shaft body 14 Elastic layer

Claims

1. a shaft body; and an elastic layer formed on an outer peripheral surface of the shaft body, the elastic layer being a layer that appears on the surface; 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, 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, a paper feed roll in which the area ratio of the second phase is in the range of 45% to 55% within any 2.5 μm × 2.5 μm square area of ​​the elastic layer, and the friction coefficient of the surface of the elastic layer is 1.0 to 2.

5.

2. 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.

3. The paper feed roll according to claim 1 or 2, wherein the elastic layer contains a hydrocarbon oil.

4. The paper feed roll according to any one of claims 1 to 3, wherein the ethylene propylene diene rubber contains both oil-extended ethylene propylene diene rubber and non-oil-extended ethylene propylene diene rubber.

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