PAPER FEEDING ROLL

Abstract

Provided is a paper feeding roll that is capable of reducing conveying noise and suppressing adhesion of paper dust. A paper feeding roll (10) is provided with: a shaft body (12); and an elastic body layer (14) that is formed on the outer circumference of the shaft body (12), wherein the elastic body layer (14) is a foamed body that contains hydrin rubber, and has a cavity (18) formed of foaming cells (16) being connected with one another is located radially inward of the elastic body layer (14). The average diameter of the foaming cells (16) located inward of the elastic body layer (14) in the radial direction is larger than the average diameter of the foaming cells (16) located outward in the radial direction. Recesses (20b) formed of foaming cells (16) being opened are provided to the outer circumferential surface (14b) of the elastic body layer (14).

Description

BACKGROUND

Technical Field

The disclosure relates to a paper feeding roll that is appropriately used in an electrophotographic apparatus such as a copying machine, a printer, a facsimile, or the like, which is of an electrophotographic type.

Description of Related Art

A paper feeding roll has a shaft body and an elastic body layer formed on an outer circumference of the shaft body. Ethylene propylene diene rubber, thermosetting polyurethane, or the like is used as a material of the elastic body layer.

REFERENCE LIST

Patent Literature 1: Japanese Laid-open No. 2015-27899

Thermosetting polyurethane has a high hardness and a low frictional coefficient in a simple substance. For this reason, for use as a material of an elastic body layer of a paper feeding roll, a plasticizer may be blended therewith. However, even when a plasticizer is blended in, the hardness is still higher than that of ethylene propylene diene rubber, and a there may be much sound (a conveyance sound) during paper feeding in some cases. Meanwhile, the ethylene propylene diene rubber has a high electrical resistance in a simple substance and paper dust is easily attached to the rubber due to static electricity. For this reason, a conducting agent may be blended with the rubber. However, in order to reduce the electrical resistance to the extent that adhesion of paper dust is prevented, it is necessary to blend in a certain amount of an electron conducting agent such as carbon. Further, as the hardness increases, the sound at the time of paper feeding becomes greater in some cases. In addition, adhesion of paper dust cannot be sufficiently prevented with a blending amount sufficient for minimizing the sound at the time of paper feeding.

SUMMARY

The disclosure provides a paper feeding roll capable of minimizing both of adhesion of paper dust and a conveyance sound.

A paper feeding roll according to the disclosure includes a shaft body; and an elastic body layer formed on an outer circumference of the shaft body, wherein the elastic body layer is a foamed body containing a hydrin rubber, and a cavity formed of foaming cells being connected with one another is provided on an inner side of the elastic body layer in a radial direction. A first recess formed of the foaming cell being opened is provided in an inner circumferential surface of the elastic body layer. A second recess formed of the foaming cell being opened is provided in an outer circumferential surface of the elastic body layer. An average diameter of the foaming cells inside the elastic body layer in the radial direction is larger than an average diameter of the foaming cells on an outer side thereof in the radial direction. The hydrin rubber contains plant-based epichlorohydrin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is an external schematic view of a paper feeding roll according to an embodiment of the disclosure, and FIG. 1(b) is a cross-sectional view taken along line A-A in FIG. 1(a).

FIG. 2(a) and FIG. 2(b) are enlarged schematic cross-sectional views of the vicinity of a surface of the paper feeding roll shown in FIG. 1(b), FIG. 2(a) shows that foaming cells are opened in an outer circumferential surface of an elastic body layer, and FIG. 2(b) shows that foaming cells are not opened in an outer circumferential surface of the elastic body layer.

FIG. 3(a) and FIG. 3(b) show enlarged cross-sectional photographs of an elastic body layer of a paper feeding roll of Example 1, FIG. 3(a) shows an inner portion, and FIG. 3(b) shows an outer portion.

DESCRIPTION OF THE EMBODIMENTS

A paper feeding roll according to the disclosure (hereinafter, simply referred to as a paper feeding roll) will be described in detail. FIG. 1(a) is an external schematic view of a paper feeding roll according to an embodiment of the disclosure, and FIG. 1(b) is a cross-sectional view taken along line A-A in FIG. 1(a). FIG. 2(a) and FIG. 2(b) are an enlarged schematic cross-sectional view of the vicinity of a surface of the paper feeding roll shown in FIG. 1(b).

A paper feeding roll 10 includes a shaft body 12, and an elastic body layer 14 formed on an outer circumference of the shaft body 12. The elastic body layer 14 is a layer (the outermost layer) that appears on a surface of the paper feeding roll 10. The elastic body layer 14 has a tubular shape (a cylindrical shape).

The elastic body layer 14 consists of a composition containing hydrin rubber. Since a hydrin rubber has ionic conductivity, reduction in electrical resistance of the elastic body layer 14 can be achieved, and a residual surface charge of the elastic body layer 14 can be suppressed to a low level to minimize adhesion of paper dust. The composition that constitutes the elastic body layer 14 may contain a polymer component that consists of only hydrin rubber or may contain another polymer component except the hydrin rubber. From a viewpoint of reduction in electrical resistance of the elastic body layer 14, the polymer component is preferably formed of hydrin rubber only.

A homopolymer of epichlorohydrin (CO), an epichlorohydrin-ethylene oxide binary copolymer (ECO), an epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (GECO), or the like, may be exemplified as the hydrin rubber. Among these, ECO and GECO containing ethylene oxide as a copolymerization component are more preferable because the materials with a lower resistance can be easily obtained as compared with those not containing ethylene oxide as a copolymerization component. In addition, GCO and GECO containing allyl glycidyl ether as a copolymerization component having double bonds are more preferable than those containing no allyl glycidyl ether as a copolymerization component since then permanent set resistance (elastic recoverability) is improved.

The hydrin rubber may contain plant-based epichlorohydrin. That is, some or all of the epichlorohydrin as the polymer component may be formed of plant-based epichlorohydrin. When the hydrin rubber contains plant-based epichlorohydrin, the rubber is excellent due to an effect of suppressing the residual surface charge to a low level and minimizing adhesion of paper dust. In addition, since renewable raw materials of natural origin are used, the hydrin rubber can be made environmentally friendly from the viewpoint of being carbon neutral.

The elastic body layer 14 is a foamed body containing hydrin rubber. Accordingly, a low hardness can be secured, and sound (a conveyance sound) during paper feeding can be easily minimized. Then, a cavity 18 formed of foaming cells 16 being connected with one another is provided inside the elastic body layer 14 in a radial direction. The foaming cells 16 inside the elastic body layer 14 in the radial direction are so-called continuous bubble types. Accordingly, sound absorbency can be improved, and sound (a conveyance sound) during paper feeding can be minimized. In addition, it is possible to further minimize a settling (become excellent due to elastic recovery). The inside of the elastic body layer 14 in the radial direction is referred to as a range of ½ of a thickness from an inner circumferential surface 14a of the elastic body layer 14 in the radial direction. In the range, the elastic body layer 14 has the cavity 18 formed of the foaming cells 16 being connected with one another. Meanwhile, the cavity 18 formed of the foaming cells 16 being connected with one another may be provided (a continuous bubble type) or may be not provided (an independent bubble type) on an outer side of the elastic body layer 14 in the radial direction. As shown in FIGS. 2(a) and 2(b), when the foamed cells 16 on the outer side in the radial direction of the elastic body layer 14 are of the so-called continuous bubble type, paper dust is collected inside from the outer circumferential surface 14b in which the foamed cells 16 are opened, the removal property for paper dust is improved, and it is possible to further minimize adhesion of paper dust to the outer circumferential surface 14b of the elastic body layer 14. If the foamed cells 16 on the outer side in the radial direction of the elastic body layer 14 are of the so-called independent bubble type, the strength of the elastic body layer 14 is superior.

An average diameter of the foaming cells 16 inside the elastic body layer 14 in the radial direction is preferably larger than an average diameter of the foaming cells 16 on an outer side thereof in the radial direction. Accordingly, sound absorbency can be improved and sound (a conveyance sound) during paper feeding can be further minimized. In addition, since the average diameter of the foaming cells 16 on an outer side thereof in the radial direction is smaller than the average diameter of the foaming cells 16 inside the radial direction, the removal property becomes excellent in scraping property of the paper dust due to the outer circumferential surface 14b in which the foaming cells 16 are opened. The average diameter of the foaming cells 16 inside in the radial direction can be obtained by measuring maximum diameters (diameters) of arbitrary three foaming cells 16 in each of arbitrary five cross sections of the elastic body layer 14, and averaging the diameters of the 15 cells. An average diameter of the foaming cells 16 on an outer side thereof in the radial direction is the same as above.

The average diameter of the foaming cells 16 inside the elastic body layer 14 in the radial direction is preferably within a range of 100 to 600 μm, and more preferably within a range of 100 to 300 μm. Accordingly, sound absorbency can be improved, and sound (a conveyance sound) during paper feeding can be further minimized. In addition, the strength of the elastic body layer 14 can be secured. Meanwhile, the average diameter of the foaming cells 16 on an outer side of the elastic body layer 14 in the radial direction is preferably within a range of 20 to 300 μm, and more preferably within a range of 20 to 100 μm. Accordingly, scraping property of paper dust of the outer circumferential surface 14b in which the foaming cells 16 are opened becomes excellent. In addition, strength of the elastic body layer 14 can be secured.

The foaming cells 16 may be opened as shown in FIG. 2(a) or the foaming cells 16 may not be opened as shown in FIG. 2(b) in the outer circumferential surface 14b of the elastic body layer 14. Preferably, the foaming cells 16 are opened in the outer circumferential surface 14b of the elastic body layer 14. As shown in FIG. 2(a), when recesses 20b formed of the foaming cells 16 being opened are provided in the outer circumferential surface 14b of the elastic body layer 14, paper dust can be scraped into the recesses 20b. Adhesion of the paper dust to the outer circumferential surface 14b of the elastic body layer 14 also can be minimized. Depending on the forming method, when a thin skin 14c is formed on the outer circumferential surface 14b of the elastic body layer 14 and the foaming cells 16 are not opened as shown in FIG. 2(b), the foaming cells 16 may be opened in the outer circumferential surface 14b of the elastic body layer 14 as shown in FIG. 2(a) by shaving off a thin portion of the outer circumferential surface 14b.

As shown in FIGS. 2(a) and 2(b), the foaming cells 16 may be opened or the foaming cells 16 may be not opened in the inner circumferential surface 14a of the elastic body layer 14. When recesses 20a formed of the foaming cells 16 being opened are provided in the inner circumferential surface 14a of the elastic body layer 14, the foaming cells 16 having relatively large diameters may be easily formed inside the elastic body layer 14 in the radial direction. That is, the average diameter of the foaming cells 16 inside the elastic body layer 14 in the radial direction is likely to be larger than the average diameter of the foaming cells 16 on an outer side thereof in the radial direction. In addition, when the foaming cells 16 inside the elastic body layer 14 in the radial direction are of the consecutive bubble type, the cavity 18 formed of foaming cells 16 being connected with one another is easily formed inside the elastic body layer 14 in the radial direction.

The elastic body layer 14 may be formed using a forming composition containing hydrin rubber through molding, extrusion molding, or the like, by a molding mold. For example, the elastic body layer 14 may be formed on the outer circumference of the shaft body 12 by coaxially installing the shaft body 12 on a hollow section of a roll molding mold, injecting an uncrosslinked forming composition, heating and curing (crosslinking) the composition, and then, releasing the mold; or by extrusion-molding the uncrosslinked forming composition on a surface of the shaft body 12.

In order to provide a configuration having the cavity 18 formed of foaming cells 16 being connected with one another inside the elastic body layer 14 in the radial direction, a configuration in which an average diameter of the foaming cells 16 inside the elastic body layer 14 in the radial direction is larger than an average diameter of the foaming cells 16 on an outer side thereof in the radial direction, or a configuration having the recesses 20a formed of foaming cells 16 being opened in the inner circumferential surface 14a of the elastic body layer 14, for example, the configuration may be adjusted such that a gas generated from a foaming agent escapes from the inside of the elastic body layer 14 in the radial direction. While the thin skin 14c is easily formed on the outer circumferential surface 14b of the elastic body layer 14 and the foaming cells 16 are not opened in the outer circumferential surface 14b of the elastic body layer 14, in order to open the foaming cells 16 in the outer circumferential surface 14b of the elastic body layer 14, for example, the outer circumferential surface 14b of the elastic body layer 14 may be cut after molding.

For example, the molding through extrusion may be performed as follows. First, an unvulcanized/unfoamed foaming rubber layer is formed over (on) an outer circumference of a core member while simultaneously extruding a forming composition containing hydrin rubber together with a metal core member having an outer circumferential surface on which no adhesive agent is applied. Next, the resultant composite is heated in high-pressure conditions, vulcanization proceeds on the outer circumferential surface only while an unfoamed state is maintained, and a vulcanized thin skin (skin layer) is formed on the entire outer circumferential surface. Here, since the metal core member is provided, vulcanization of the complex proceeds through thermal conduction from the outer circumferential surface. Accordingly, the vulcanization proceeds gradually from the outside toward the inside in the radial direction. Next, a rubber tube is formed of such a gradient material except the core member, and vulcanization/foaming proceeds through heating under a normal pressure. Since the rubber tube is formed of the gradient material, the foaming cells gradually enlarge from the outside toward the inside in the radial direction. In addition, since the inner circumferential surface is an open system and in an unvulcanized state, the foaming cells are opened in the inner circumferential surface. Meanwhile, since the outer circumferential surface is in the vulcanized state, the foaming cells are not formed on the outer circumferential surface, and the foaming cells are not opened in the outer circumferential surface.

While the vulcanization under the pressurized condition is not particularly limited thereto, heating for about 1 to 20 minutes is, for example, performed under a pressurized condition of 0.5 to 2.0 MPa and a temperature condition of 100 to 200° C. While the vulcanization under a normal pressure condition is not particularly limited thereto, heating for about 10 to 60 minutes is, for example, performed under a temperature condition of 100 to 200° C.

Since the hydrin rubber before crosslinking is normally a millable rubber, a foaming agent is basically used to make a foamed body. Accordingly, a crosslinking agent, a foaming agent, or the like, is contained in the forming composition, in addition to the hydrin rubber before crosslinking.

Azobisisobutyronitrile (AIBN), azocarbonamide, N,N′-dinitropentamethylene tetramine (DPT), potassium bicarbonate, urea, 4,4′-oxybis(benzenesulfonyl hydrazide), or the like, may be exemplified as the foaming agent. A content of the foaming agent is, for example, within a range of 5 to 20 parts by mass with respect to 100 parts by mass of the hydrin rubber that is uncrosslinked (before crosslinking) in the forming composition.

A urea-based foaming aid, a metal oxide-based foaming aid, a metal soap-based foaming aid, a salicylic acid-based foaming aid, or the like, is exemplified as the foaming aid. These aids may be used as individually or a combination of two or more aids, and are optimally selected according to a type of foaming agent. For example, zinc oxide (II) or the like may be exemplified as a metal oxide-based foaming aid. For example, calcium stearate or the like is exemplified as the metal soap-based foaming aid. For example, salicylic acid is exemplified as the salicylic acid-based foaming aid. The content of the foaming aid is, for example, in a range of 5 to 20 parts by mass with respect to 100 parts by mass of an uncrosslinked hydrin rubber in the formulation.

A sulfur crosslinking agent, a peroxide crosslinking agent or a dechlorination crosslinking agent may be exemplified as the crosslinking agent. These crosslinking agents may be individually used or may be used as a combination of two or more agents.

A sulfur crosslinking agent that is known from the related art such as powdery sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, a thiuram-based vulcanization accelerator, a polymeric polysulfide, or the like, may be exemplified as the sulfur crosslinking agent.

A peroxide crosslinking agent that is known from the related art such as a peroxy ketal, a dialkyl peroxide, a peroxy ester, a ketone peroxide, a peroxy dicarbonate, a diacyl peroxide, a hydroperoxide, or the like, may be exemplified as the peroxide crosslinking agent.

A dithiocarbonate compound may be exemplified as a dechlorination crosslinking agent. More specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, 5,8-dimethylquinoxaline-2, 3-dithiocarbonate, or the like, may be exemplified.

A blending quantity of the crosslinking agent 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 further preferably within a range of 0.5 to 1.5 parts by mass with respect to 100 parts by mass of an uncrosslinked hydrin rubber from a viewpoint that bleeding is then difficult or the like.

When a dechlorination crosslinking agent is used as the crosslinking agent, a dechlorination crosslinking accelerator may be used in combination therewith. 1,8-diazabicyclo(5,4,0)undecene-7 (hereinafter, abbreviated as DBU) or a weak acid salt thereof may be exemplified as a dechlorination crosslinking accelerator. While a dechlorination crosslinking accelerator is used as the form of DBU in some exemplary embodiments, a dechlorination crosslinking accelerator may be used in a form of a weak acid salt thereof in view of a handling aspect. Examples of weak acid salts of DBU include carbonate, stearate, 2-ethylhexylate, benzoate, salicylate, 3-hydroxy-2-naphthoate, phenol resin, 2-mercaptobenzothiazole, and 2-mercaptobenzimidazole salts, and the like.

A content of the dechlorination crosslinking accelerator 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 further preferably within a range of 0.5 to 1.5 parts by mass with respect to 100 parts by mass of the uncrosslinked hydrin rubber from a viewpoint that bleeding is difficult or the like.

While the elastic body layer 14 and the composition that composes the elastic body layer 14 may contain a conducting agent from a viewpoint of reduction in electrical resistance, the elastic body layer 14 and the composition may not contain an electron conducting agent such as carbon or the like if possible from a viewpoint that sound (a conveyance sound) during paper feeding due to an increase in hardness is minimized or the like. Although an electron conducting agent such as carbon may be included in the composition as long as it does not greatly affect an increase in hardness, it is more preferable that an electron conducting agent such as carbon not be included. Meanwhile, since the influence applied to the increase in hardness is small, the ion conducting agent may be contained or may not be contained. Carbon black, graphite, c-TiO₂, c-ZnO, c-SnO₂ (c—means conductivity), or the like, is exemplified as the electron conducting agent. Quaternary ammonium salt, borate, surfactant, or the like, is exemplified as the ion conducting agent.

Various types of additive may be appropriately added to the elastic body layer 14 and the composition that composes the elastic body layer 14 according to necessity. As examples of additives, lubricants, vulcanization accelerators, antioxidants, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoaming agents, pigments, mold release agents and the like may be mentioned.

A volume resistivity of the elastic body layer 14 may be adjusted to a predetermined volume resistivity by using the above composition. From a viewpoint that adhesion of paper dust is minimized or the like, a volume resistivity of the elastic body layer 14 may be set to a range of 10² to 10¹⁰ Ω·cm, 10³ to 10⁹ Ω·cm, 10⁴ to 10⁸ Ω·cm, or the like.

In addition, in the elastic body layer 14, a residual surface charge may be adjusted to a predetermined range using the composition. From a viewpoint that adhesion of paper dust is minimized, the residual surface charge of the elastic body layer 14 is preferably within a range of 0 to 20 V, and more preferably, within a range of 0 to 10 V.

The hardness of the elastic body layer 14 may be set to a predetermined range. From a viewpoint that an effect of minimizing sound during paper feeding due to reduction in hardness is excellent and excellent strength can be secured, the hardness is preferably within a range of 30 to 60°, and more preferably, within a range of 30 to 50°. In order to obtain a predetermined low hardness, the electron conducting agent is preferably not contained. The hardness of the elastic body layer 14 may be measured by (a JIS-A hardness).

A thickness of the elastic body layer 14 is not particularly limited and may be appropriately set within a range of 0.1 to 10 mm according to a use or the like.

The shaft body 12 is not particularly limited as long as the shaft body 12 has conductivity. Specifically, a solid body formed of a metal such as iron, stainless steel, aluminum, or the like, a metal core constituted by a hollow body, or the like, may be exemplified as the shaft body. An adhesive agent, a primer, or the like may be applied to a surface of the shaft body 12 as necessity. That is, the elastic body layer 14 may be adhered to the shaft body 12 via an adhesive agent layer (a primer layer). Conductivity may be applied to adhesives, primers and the like as necessary.

According to the paper feeding roll 10 having the above-mentioned configuration, since the elastic body layer 14 is a foamed body containing hydrin rubber and the cavity 18 formed of foaming cells 16 being connected with one another is provided inside the elastic body layer 14 in the radial direction, both of adhesion of paper dust and a conveyance sound can be minimized.

The configuration of the paper feeding roll according to the disclosure is not limited to the configuration shown in FIG. 1. For example, in the paper feeding roll 10 shown in FIG. 1, another elastic body layer may be provided between the shaft body 12 and the elastic body layer 14.

EXAMPLES

Hereinafter, the disclosure will be described in detail using examples and comparative examples.

Example 1

<Preparation of Composition for Elastic Body Layer>

A composition for a hydrin rubber-based elastic body layer was obtained by kneading together 100 parts by mass of an epichlorohydrin rubber (ECO<1>) [“Hydrin T3106” manufactured by Nippon Zeon Co., Ltd.], 0.5 parts by mass of sulfur [manufactured by Tsurumi Chemical Industry Co., Ltd.] as a vulcanizing agent, 5.0 parts by mass of two types of zinc oxides [manufactured by Mitsui Mining & Smelting Co., Ltd.] and 10.0 parts by mass of a hydrotalcite [trade name “DHT4A” manufactured by Kyowa Chemical Industry Co., Ltd.] as vulcanizing aids, 1.0 part by mass of a vulcanization accelerator A [trade name “Sanceler-CZ” manufactured by Sanshin Chemical Industry Co., Ltd.], 1.0 part by mass of a vulcanization accelerator B [trade name “Accel TBT” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.], and 10.0 parts by mass of azodicarbonamide [trade name “Selmark RUB” manufactured by Sankyo Kasei Sangyo Co., Ltd.] as a foaming agent using a kneader.

<Fabrication of Paper Feeding Roll>

A complex having an unvulcanized/unfoamed foaming rubber layer on an outer circumferential surface of a core member was obtained by simultaneously extruding a composition for a hydrin rubber-based elastic body layer together with a core member (φ6, made of SUS304) having an outer circumferential surface on which an adhesive agent was not applied using an extrusion molding apparatus having an extrusion molding section having a cylinder diameter of 40φ and a cross type head. Next, the obtained complex was placed in a pressurization oven, the inside of the oven was pressurized to 1 MPa, and then, the oven was heated to 150° C. and a heat treatment was performed for 15 minutes. A thin skin was formed on the surface by performing vulcanization in the vicinity of the outer circumferential surface while foaming was minimized in the unvulcanized/unfoamed foaming rubber layer through heating under pressurization. The foaming rubber layer was brought into a half-vulcanized/unfoamed state through the heat treatment. The result of visually observing the surface of the composite after the heat treatment was that it was recognized that a thin skin (skin layer) was formed and that no foamed cells were found over the entire outer circumferential surface. Next, the pressure in the oven was reduced to a normal pressure, and the core member was removed from the complex. The heat treatment was performed with respect to the obtained rubber tube (the foaming rubber layer in a half-vulcanized/unfoamed state) in the oven under a normal pressure at 150° C. for 30 minutes. Foaming/vulcanization of the foaming rubber layer was performed through the heat treatment. The foaming rubber layer was in a vulcanized/foamed state through the heat treatment. A shaft body was inserted into a rubber tube (a thickness of 3 mm) formed of a foamed body containing the hydrin rubber that was obtained in this way, and the paper feeding roll was obtained. Polishing was not performed on an outer circumferential surface of the obtained elastic body layer.

<Structure of Elastic Body Layer>

In the elastic body layer of the obtained paper feeding roll, the outer circumferential surface and the inner circumferential surface were visually observed. In addition, a cross section in a radial direction was observed through a photograph using a laser microscope manufactured by Keyence Corporation. The photograph by the laser microscope is shown in FIG. 3. FIG. 3(a) is a laser microscope photograph inside the elastic body layer in the radial direction, and FIG. 3(b) is a laser microscope photograph outside the elastic body layer in the radial direction. These are photographs photographed with the same magnitude. The thin skin (the skin layer) is formed on the entire outer circumferential surface of the obtained elastic body layer, and recesses formed of foaming cells being opened are not formed in the entire outer circumferential surface of the elastic body layer. Recesses formed of foaming cells being opened are formed in the entire inner circumferential surface of the elastic body layer. As shown in FIG. 3(a), a cavity formed of foaming cells being connected with one another is provided inside the elastic body layer in the radial direction. As shown in FIG. 3(b), a cavity formed of foaming cells being connected with one another is provided outside the elastic body layer in the radial direction. From FIGS. 3(a) and 3(b), an average diameter of the foaming cells inside the elastic body layer in the radial direction is larger than an average diameter of the foaming cells on an outer side thereof in the radial direction.

Example 2

A paper feed roll was produced in the same manner as in Example 1 except that in the preparation of a composition for the elastic layer, the following plant-derived epichlorohydrin was used as the epichlorohydrin rubber (ECO). The outer circumferential surface of the obtained elastic layer was not polished. The structure of the elastic layer was the same as in Example 1.

• • Epichlorohydrin rubber (ECO<2>): trade name “Epichlomer CG102” manufactured by Daiso Co., Ltd.

Example 3

Like Example 2 except that polishing of the outer circumferential surface of the obtained elastic body layer was performed (a polished thickness of 100 μm) and the recesses formed of foaming cells being opened were provided in the entire outer circumferential surface of the elastic body layer, the paper feeding roll was fabricated. A structure except the outer circumferential surface of the elastic body layer is the same as in Example 1.

Example 4

In preparation of the composition for the elastic body layer, the paper feeding roll was fabricated like in Example 3 except that 0.3 parts by mass of an ion conducting agent (tetramethylammonium perchlorate) was blended in. Like Example 3, polishing of the outer circumferential surface of the obtained elastic body layer was performed (a polished thickness of 100 μm), and the recesses formed of foaming cells being opened were provided in the entire outer circumferential surface of the elastic body layer. A structure except the outer circumferential surface of the elastic body layer is the same as in Example 1.

Comparative Example 1

<Preparation of Composition for Elastic Body Layer>

A composition for a urethane-based elastic body layer was obtained by kneading together 90 parts by mass of polyol (“EP828” manufactured by Mitsui Chemical Polyurethane Inc.), 10 parts by mass of a foam breaker (“POP31-28” manufactured by Mitsui Chemical Polyurethane Inc.), 1 part by mass of an amine-based catalyst (“Kao riser No. 31” manufactured by Kao Corp.), 0.3 parts by mass of a amine-based catalyst (“Toyocat HX35” manufactured by Tosoh Corporation), 0.1 parts by mass of a tin-based catalyst (dibutyl tin dilaurate), 3 parts by mass of a silicone-based foam stabilizer (“L5309” manufactured by GE Toshiba silicones Co., Ltd.), 2 parts by mass of water, and 26.9 parts by mass of isocyanate (“Sumidur VT80” manufactured by Sumitomo Bayer Urethane Co., Ltd.) using a planetary mixer.

<Fabrication of Paper Feeding Roll>

An elastic body layer (a thickness of 3 mm) formed of a urethane-based foamed body was formed by setting a core metal (a diameter of 6 mm) into a die of a pipe-shaped molding mold, injecting a composition for a urethane-based elastic body layer into the die, and foaming and curing the composition under a condition at a temperature of 90° C. for 30 minutes. Accordingly, the paper feeding roll was obtained. The outer circumferential surface of the obtained elastic body layer was not polished. A structure of the elastic body layer is the same in Example 1.

Comparative Example 2

<Preparation of Composition for Elastic Body Layer>

A composition for an EPDM-based elastic body layer was obtained by kneading together 100 parts by mass of an ethylene-propylene-diene rubber (“EPT4045” manufactured by Mitsui Chemical Co., Ltd.), 5 parts by mass of two types of zinc oxides (manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part by mass of a stearic acid (“Lughnuck S-30” manufactured by Kao Corp.), 30 parts by mass of process oil (“Diana Process PW-380” manufactured by Idemitsu Kosan Co., Ltd.), 15 parts by mass of dinitrosopentamethylenetetramine (a foaming agent), 1 part by mass of sulfur (manufactured by Tsurumi Chemical Industry Co., Ltd.), 2 parts by mass of dibenzothiazyl disulfide (vulcanization accelerator) (“Nocceler DM-P” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.), and 1 part by mass of tetra methyl thiuram monosulfide (vulcanization accelerator) (“Nocceler TS” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.) using a kneader.

<Fabrication of Paper Feeding Roll>

After a core metal was set in a die of a pipe-shaped molding mold and the composition for the EPDM-based elastic body layer was injected into the die, the composition was heated at a temperature of 160° C. for 40 minutes, the composition for the elastic body layer was vulcanized/cured/foamed, and the elastic body layer (a thickness of 3 mm) formed of the EPDM-based foamed body was formed. Accordingly, the paper feeding roll was obtained. Polishing of the outer circumferential surface of the obtained elastic body layer was not performed. A structure of the elastic body layer is the same as in Example 1.

Comparative Example 3

In preparation of the composition for the elastic body layer, the paper feeding roll was fabricated like in Comparative example 2 except that 15 parts by mass of carbon black (“Ketjen EC300J” manufactured by Lion Inc.) was blended as the electron conducting agent. Polishing of the outer circumferential surface of the obtained elastic body layer was not performed. A structure of the elastic body layer is the same in Example 1.

Comparative Example 4

The paper feeding roll was fabricated like in Example 1 except that the foamed body was not provided while no foaming agent was blended in preparation of the composition for the elastic body layer. Polishing of the outer circumferential surface of the obtained elastic body layer was not performed.

Comparative Example 5

The composition for the elastic body layer was prepared like in Example 1 except that 15 parts by mass of microcapsules (Matsumoto Yushi-Seiyaku Co., Ltd. “Microsphere F60”) is used instead of azodicarbonamide. Then, like Comparative example 2, the paper feeding roll was fabricated using the pipe-shaped molding mold. Polishing of the outer circumferential surface of the obtained elastic body layer was not performed. A cavity formed of foaming cells being connected with one another is not provided inside the elastic body layer in the radial direction (a range of ½ of a thickness from the inner circumferential surface in the radial direction).

Estimation of paper dust adhesiveness and sound (a conveyance sound) during paper feeding in the obtained paper feeding rolls was performed.

(Paper Powder Adhesiveness)

While rotating the paper feed roll in the circumferential direction in an environment of 23° C.×53% RH at a rotational speed of 70 rpm, a 100 μA (constant current) corona current was applied with a distance of 10 mm between the core of the corotron (using direct current power supply) and the surface of the elastic layer to charge the surface of the elastic layer. Next, at a position rotated by 90 degrees in the rotational direction from the charging position, the surface potential of the surface of the elastic layer was measured at a central portion in the axial direction with 1 mm between the probe of the surface electrometer and the surface of the elastic layer. The value was used as the residual surface charge on the surface of the elastic body layer. The shaft body and the corotron were grounded. The paper dust adhesiveness was estimated from the value of the residual surface charge. The paper dust adhesiveness was estimated as particularly good “” when the residual surface charge was less than 15 V, estimated as good “O” when the residual surface charge was 15V or more and less than 20V, estimated as slightly poor “Δ” when the residual surface charge was 20V or more and less than 150V, and estimated as poor “X” when the residual surface charge was 150V more.

(Conveyance Sound)

The paper feeding roll was assembled as a paper feeding roll in an “Image RUNNER ADVANCE C5051” manufactured by Canon Inc. 300,000 sheets of plain paper were passed through and occurrence of a conveyance sound was checked in an environment of 23° C.×53% RH. In a case in which a driving mechanism sound that became a source of noise when an operation had started was generated, but no discomforting sound caused by the incorporated paper feed roll was heard, the sound was determined as particularly good “”, a case in which an discomforting sound was within an allowable range although slightly heard was determined as good “O”, a case in which an discomforting sound was unacceptably large sometimes was determined as slightly poor “Δ”, and a case in which an discomforting sound was unacceptably large frequently was determined as poor “X”.

(Hardness)

A JIS-A hardness on the surface of the elastic body layer was measured. A case in which the hardness is 60° or less was determined as low hardness “O,” a case in which the hardness is larger than 60° and 70° or less was determined as medium hardness “Δ” and a case in which the hardness is larger than 70° was determined as high hardness “X.”

(Volume Resistivity)

Measurement of a resistance of the paper feeding roll as an initial resistance value was performed. Under N/N environment (23° C., RH50%), a DC voltage of 200V was applied to an end portion of a core metal with a load of 500 g at both ends of the paper feeding roll, and a roll resistance value for one minute at a rotational speed of 30 rpm was measured.

TABLE 1
	Examples	Comparative exanples
	1	2	3	4	1	2	3	4	5
Type of polymer	ECO<1>	ECO<2>	ECO<2>	ECO<2>	Urethane	EPDM	EPDM	ECO<1>	ECO<1>
Electronic	None	None	None	None	None	None	Exist	None	None
conducting agent
Ionic conducting	None	None	None	Exist	None	None	None	None	None
agent
Foamed/Unfoamed	Foamed	Foamed	Foamed	Foamed	Foamed	Foamed	Foamed	Unfoamed	Foamed
Inside cells	Continuous	Continuous	Continuous	Continuous	Continuous	Continuous	Continuous	—	No continuous
	bubbles	bubbles	bubbles	bubbles	bubbles	bubbles	bubbles		bubbles
Outside cells	Continuous	Continuous	Continuous	Continuous	Continuous	Continuous	Continuous	—	No continuous
	bubbles	bubbles	bubbles	bubbles	bubbles	bubbles	bubbles		bubbles
Outer	Cell not	Cell not	Cell open	Cell open	Cell not	Cell not	Cell not	Cell not	Cell not
circumferential	open	open			open	open	open	open	open
surface
Inner circumferential	Cell open	Cell open	Cell open	Cell open	Cell open	Cell open	Cell open	Cell open	Cell open
surface
Average cell	Inside >	Inside >	Inside >	Inside >	Inside >	Inside >	Inside >	Inside >	Inside >
diameter comparison	Outside	Outside	Outside	Outside	Outside	Outside	Outside	Outside	Outside
Volume resistivity	5.0 × 107	5.0 × 107	5.0 × 107	1.0 × 107	5.0 × 109	1.0 × 1014	5.0 × 107	5.0 × 107	5.0 × 107
(Ω · cm)
Hardness	◯	◯	◯	◯	Δ	◯	X	X	◯
Surface residual	5	5	5	5	50	1200	100	1	5
charge (V)
Paper powder	◯				Δ	X	Δ	◯	◯
adhesiveness
Conveyance sound	◯	◯			Δ	◯	X	X	X

In Comparative Example 1, since only thermosetting polyurethane having a high hardness and a low frictional coefficient was used for the polymer of the elastic body layer in a simple substance, a conveyance sound could not be sufficiently minimized. Also, since the residual surface charge was somewhat large, there was little effect of preventing adhesion of paper dust. In Comparative example 2, EPDM having high resistivity was used for polymer of the elastic body layer in a simple substance. For this reason, the residual surface charge was increased and adhesion of the paper dust was not minimized. When the electron conducting agent such as carbon or the like was blended with the EPDM (Comparative example 3), while the residual surface charge was reduced and adhesion of the paper dust was somewhat minimized, the hardness was increased and the conveyance sound was not minimized. In Comparative example 4, while hydrin rubber was used for polymer of the elastic body layer, since the hydrin rubber was unfoamed, a conveyance sound was not minimized. In Comparative example 5, while the elastic body layer was a foamed body containing hydrin rubber, a cavity formed of foaming cell being connected with one another was not provided (an independent bubble) outside the elastic body layer in the radial direction (a range of ½ of a thickness from the circumferential surface in the radial direction). For this reason, a conveyance sound is not minimized.

On the other hand, in the example, the elastic body layer is a foamed body containing hydrin rubber, and a cavity formed of foaming cells being connected with one another is provided (consecutive bubbles) outside the elastic body layer in the radial direction (a range of ½ of a thickness from the circumferential surface in the radial direction). For this reason, the residual surface charge is reduced and adhesion of the paper dust is minimized. In addition, a conveyance sound is also minimized. Further it could be ascertained from Examples 1 and 2 that, since the hydrin rubber contains plant-based epichlorohydrin, the residual surface charge is further reduced and adhesion of the paper power is further minimized. In addition, it could be ascertained from Examples 2 and 3 that, since the recesses formed of foaming cells being opened are provided in the outer circumferential surface of the elastic body layer, the conveyance sound is further minimized. In addition, it could be ascertained from Examples 2 and 4 that, since the residual surface charge is sufficiently minimized even when the ion conducting agent is not blended, adhesion of the paper dust is minimized even when the ion conducting agent is not blended.

A paper feeding roll according to the disclosure includes a shaft body; and an elastic body layer formed on an outer circumference of the shaft body, wherein the elastic body layer is a foamed body containing a hydrin rubber, and a cavity formed of foaming cells being connected with one another is provided on an inner side of the elastic body layer in a radial direction.

An average diameter of the foaming cells inside the elastic body layer in the radial direction may be larger than an average diameter of the foaming cells on an outer side thereof in the radial direction. The hydrin rubber may contain a plant-based epichlorohydrin. A recess formed of the foaming cell being opened may be provided in an outer circumferential surface of the elastic body layer. A recess formed of the foaming cell being opened may be provided in an inner circumferential surface of the elastic body layer.

According to the paper feeding roll of the disclosure, since the elastic body layer is a foamed body containing hydrin rubber and the cavity formed of foaming cells being connected with one another is provided inside the elastic body layer in the radial direction, both of adhesion of paper dust and a conveyance sound can be minimized.

When the average diameter of the foaming cells inside the elastic body layer in the radial direction is larger than the average diameter of the foaming cells on an outer side thereof in the radial direction, an effect of minimizing a conveyance sound becomes better. When the hydrin rubber contains plant-based epichlorohydrin, an effect of minimizing adhesion of paper dust becomes better. When the recesses formed of foaming cells being opened are provided in the outer circumferential surface of the elastic body layer, the paper dust is scraped into the recess. Even in this case, adhesion of paper dust to the outer circumferential surface of the elastic body layer can be suppressed.

Hereinabove, while the embodiments and the examples of the disclosure have been described, the disclosure is not limited to the above-mentioned embodiments and examples and various modifications may be made without departing from the spirit of the disclosure.

Claims

1. A paper feeding roll comprising: a shaft body; andan elastic body layer formed on an outer circumference of the shaft body,wherein the elastic body layer is a foamed body containing a hydrin rubber, and a cavity formed of foaming cells being connected with one another is provided inside the elastic body layer in a radial direction;a first recess formed of the foaming cell being opened is provided in an inner circumferential surface of the elastic body layer;a second recess formed of the foaming cell being opened is provided in an outer circumferential surface of the elastic body layer;an average diameter of the foaming cells inside the elastic body layer in the radial direction is larger than an average diameter of the foaming cells on an outer side thereof in the radial direction; andthe hydrin rubber contains plant-based epichlorohydrin.