JP7695605B2 - Rubber composition for paper feed member and paper feed roller - Google Patents

Description

The present invention relates to a rubber composition for paper feed members used to form paper feed members, such as paper feed rollers and separation pads, that feed sheets in office automation equipment such as laser printers, and a paper feed roller that includes a roller body made of a cross-linked product of the rubber composition for paper feed members.

Paper feed members used in devices that use electrophotography, such as laser printers, are required to have excellent resistance to the ozone generated inside the device, and EPDM, which has few unsaturated bonds and is resistant to ozone degradation, is preferably used as the rubber (Patent Document 1, etc.).

JP 2000-302268 A JP 2007-112836 A JP 2014-111691 A

When the sheets being fed are particularly ones that produce a lot of paper dust, continued feeding can cause the coefficient of friction of the paper feed member to drop significantly from its initial value due to the accumulation of paper dust, resulting in poor paper feeding.
As a countermeasure, it is conceivable to set the initial friction coefficient of the paper feed member to a larger value in order to keep the decrease in the friction coefficient of the paper feed member within a range in which paper feed failure does not occur even if paper feed is continued.

In Patent Document 1, a separation pad (rubber member for preventing double feeding) serving as a paper feeding member is formed using a rubber composition prepared by blending a tackifier together with a peroxide crosslinking agent for crosslinking EPDM (ethylene-propylene-diene copolymer rubber) to the EPDM.
However, since EPDM, which has an inherently low coefficient of friction, is used, it is difficult to significantly improve the coefficient of friction of the paper feed member by simply adding a tackifier.

In other words, when a separation pad is formed using the rubber composition of Patent Document 1, the initial friction coefficient can be increased to a range that allows use as a separation pad, as described in Patent Document 1.
However, the paper feed members, particularly the roller body of the paper feed roller, are required to have a coefficient of friction in a range higher than that of the separation pad.

Therefore, even if the roller body is formed using the rubber composition of Patent Document 1, the initial friction coefficient of the roller body cannot be sufficiently increased to a range where paper feeding problems do not occur even when paper feeding is repeated.
Furthermore, when the rubber composition of Patent Document 1 is used to form a roller body, the abrasion resistance of the roller body may be significantly reduced.

The object of the present invention is to provide a rubber composition for paper feeding members which contains an ethylene-α-olefin resin such as EPDM having excellent ozone resistance, and which can sufficiently increase the initial friction coefficient of the roller body of a paper feed roller to a range where paper feeding problems do not occur when paper feeding is repeated, and which can also suppress a decrease in the abrasion resistance of the roller body.
Another object of the present invention is to provide a paper-feeding roller having a roller body formed using the rubber composition for paper-feeding members.

The present invention is a rubber composition for paper-feeding members, which comprises a rubber containing an ethylene-α-olefin copolymer rubber, a cross-linking component for cross-linking the rubber, and a tackifier, the cross-linking component containing at least a sulfur-based cross-linking agent, the tackifier being an alkylphenol resin, and the proportion of the alkylphenol resin is 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber.

The present invention also relates to a paper feed roller that includes a roller body made of a cross-linked product of the rubber composition for paper feed members.

According to the present invention, it is possible to provide a rubber composition for paper feeding members which contains an ethylene-alpha olefin resin having excellent ozone resistance, and which can sufficiently increase the initial friction coefficient of the roller body of a paper feed roller, etc., to a range where paper feeding problems do not occur when paper feeding is repeated, and which can also suppress a decrease in the wear resistance of the roller body, etc.
Furthermore, according to the present invention, it is possible to provide a paper-feeding roller having a roller body formed using the rubber composition for paper-feeding members.

1 is an enlarged perspective view showing a portion of a paper feed roller according to an embodiment of the present invention; FIG. 4 is a diagram for explaining a method for measuring the friction coefficient of a paper feed roller in an embodiment of the present invention and a comparative example.

<Rubber composition for paper feed member>
As described above, the rubber composition for a paper feeding member of the present invention contains a rubber containing an ethylene-α-olefin copolymer rubber such as EPDM, a crosslinking component for crosslinking the rubber, and a tackifier, and the crosslinking component contains at least a sulfur-based crosslinking agent,
The tackifier is an alkylphenol resin.
The proportion of the alkylphenol resin is 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of rubber.

According to the present invention, by crosslinking a rubber containing an ethylene-α-olefin copolymer rubber with a sulfur-based crosslinking agent, the effect of increasing the friction coefficient achieved by blending an alkylphenol resin as a tackifier in the above-mentioned specified ratio can be further improved.
Therefore, even for the roller body of a paper feed roller, which requires a higher friction coefficient, not to mention the separation pad, it is possible to sufficiently increase the initial friction coefficient to a range that does not cause paper feeding problems when paper is fed repeatedly.

Furthermore, according to the present invention, by crosslinking the rubber containing the ethylene-α-olefin copolymer rubber with a sulfur-based crosslinking agent, it is possible to suppress a significant decrease in abrasion resistance even when an alkylphenol resin is blended as a tackifier in the above-mentioned specified ratio.
These facts are also evident from the results of the examples and comparative examples described below.
<Rubber>
As the rubber, various rubbers including at least an ethylene-α-olefin copolymer rubber, any of which can be crosslinked with a sulfur-based crosslinking agent, can be used.

Other rubbers that may be used in combination with the ethylene-α-olefin copolymer rubber include, for example, one or more of natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), fluororubber (FKM), chloroprene rubber (CR), silicone rubber (VMQ), urethane rubber (U), and ethylene propylene rubber.

However, in consideration of improving the ozone resistance and weather resistance of the roller body of the paper feed roller as a paper feeding member, it is preferable to use only ethylene-α-olefin copolymer rubber (including the use of two or more types of ethylene-α-olefin copolymer rubber in combination) as the rubber.
(Ethylene-α-olefin copolymer rubber)
Among the rubbers, as the ethylene-α-olefin copolymer rubber, various copolymer rubbers that contain ethylene and α-olefin as copolymerization components and can be crosslinked with a sulfur-based crosslinking agent can be used, and in particular, copolymer rubbers of ethylene, α-olefin and diene are preferred.

Examples of dienes constituting such copolymer rubber include ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, etc., and the α-olefin is preferably propylene or butene.
Examples of the ethylene-α-olefin-diene copolymer rubber include ethylene-propylene-diene copolymer rubber (EPDM), ethylene-butene-diene copolymer rubber (EBDM), and ethylene-propylene-butene-diene copolymer rubber (EPBDM).

In particular, EPDM, which has excellent crosslinkability with a sulfur-based crosslinking agent, is preferred.
・EPDM
As the EPDM, various copolymers in which ethylene, propylene, and diene are copolymerized can be used.
In addition, there are two types of EPDM: an oil-extended type in which the flexibility is adjusted by adding an extender oil, and a non-oil-extended type in which no extender oil is added. Either type of EPDM may be used in the present invention.

Specific examples of non-oil-extended EPDM include, but are not limited to, the following various EPDMs.
Esprene (registered trademark) 301, 301A, 501A, 502, 505, 505A, 512F, 532, 552, 586, 5206F, 5527F, and the like, manufactured by Sumitomo Chemical Co., Ltd.
NORDEL (registered trademark) IP3430, IP3640, IP3720P, IP3722P, IP3772P EL, IP3745P, IP3745P EL, IP3760P, IP4520, IP4570, IP4640, IP4725P, IP4760P, IP4770R, IP4770P, IP4770P EL, IP4770R EL, IP4785HM, IP4820P, IP5565, and the like, manufactured by The Dow Chemical Company.

EP21, EP51, EP25, EP123, EP103AF, EP107F, EP57F/C, EP93, and the like, manufactured by JSR Corporation.
Mitsui EPT 1045, 1070, 2060M, 3045, 3070, 3091, 3092M, 3110M, 4070, X-3012P, 3092PM, and the like, manufactured by Mitsui Chemicals, Inc.
Specific examples of the oil-extended EPDM include, but are not limited to, the following various EPDMs:

Esprene 600F, 601F, 603, 670F, 6101, 7456, etc., manufactured by Sumitomo Chemical Co., Ltd.
EP98 manufactured by JSR Corporation, etc.
Mitsui EPT X-3042E manufactured by Mitsui Chemicals, Inc., etc.
One or more of these non-oil-extended EPDMs and/or oil-extended EPDMs can be used.

In addition, when an oil-extended rubber is used as the rubber such as EPDM, the proportions of various components such as the cross-linking component and the tackifier may be set by defining the amount of rubber contained as a solid content in the oil-extended rubber as the amount of that rubber.
<Crosslinking component>
As the crosslinking component, a sulfur-based crosslinking agent is used as described above.

This makes it possible to further improve the effect of increasing the coefficient of friction of the paper-feeding member by blending an alkylphenol resin as a tackifier, compared to the conventional crosslinking using a peroxide crosslinking agent.
Therefore, even for paper feeding components such as the separation pad and the roller body of a paper feed roller, which require a higher range of friction coefficients, it is possible to sufficiently increase the initial friction coefficient to a range that does not cause paper feeding problems when paper feeding is repeated.

In addition, when an alkylphenol resin is blended as a tackifier, it is possible to suppress a significant decrease in the wear resistance of the roller body and the like.
(Sulfur-based crosslinking agent)
Examples of the sulfur-based crosslinking agent include powdered sulfur, powdered sulfur in oil, precipitated sulfur, colloidal sulfur, dispersible sulfur, and other sulfur-containing organic compounds such as tetramethylthiuram disulfide and N,N-dithiobismorpholine, with sulfur being particularly preferred.

The proportion of sulfur can be set arbitrarily, but is preferably at least 0.5 parts by mass and at most 2 parts by mass per 100 parts by mass of the total amount of rubber.
If the proportion of sulfur is less than this range, the crosslinking rate of the entire rubber composition for paper feed members will be slow, and the time required for crosslinking will be long, which may reduce the productivity of paper feed members such as paper feed rollers.

If the proportion of sulfur exceeds the above range, the compression set after crosslinking may become large, or the excess sulfur may bloom on the surface of the paper feed member.
When using, for example, oil-containing powdered sulfur, dispersible sulfur, or the like, the above ratio refers to the ratio of sulfur itself as an active ingredient contained therein.
When an organic sulfur-containing compound is used as the crosslinking agent, the proportion thereof is preferably adjusted so that the proportion of sulfur contained in the molecule per 100 parts by mass of the total amount of rubber falls within the above range.

(Crosslinking Accelerator)
As the crosslinking component, it is preferable to use a so-called crosslinking accelerator in combination in order to adjust the rate of progress of the crosslinking reaction of the rubber by the sulfur-based crosslinking agent.
Examples of the crosslinking accelerator include inorganic accelerators such as slaked lime, magnesia (MgO), litharge (PbO), etc., and the following various organic accelerators, which may be used alone or in combination of two or more thereof.

Guanidine-based accelerators such as 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatechol borate.
Thiazole accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide.

Sulfenamide accelerators such as N-tert-butyl-2-benzothiazolylsulfenamide and N-cyclohexyl-2-benzothiazolylsulfenamide.
Thiuram accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, and dipentamethylenethiuram tetrasulfide.

Dithiocarbamate accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dibutyldithiocarbamate.
Thiourea accelerators such as N,N'-diphenylthiourea, trimethylthiourea, and N,N'-diethylthiourea.
The proportion of the crosslinking accelerator can be set arbitrarily depending on the type, but is usually preferably at least 0.1 part by mass, particularly preferably at least 0.2 part by mass, and at most 5 parts by mass, particularly preferably at most 3 parts by mass, per 100 parts by mass of the total amount of rubber.

<Alkylphenol resin>
As the alkylphenol resin, various alkylphenol resins capable of functioning as a tackifier for rubber can be used.
Specific examples of the alkylphenol resin include, but are not limited to, the following various alkylphenol resins.

TACKIROL (registered trademark) 130 (alkylphenol-formaldehyde resin), 160 (alkylphenol-acetaldehyde resin), EP-20 (alkylphenol-formaldehyde resin), and EP-30 (alkylphenol-acetaldehyde resin), manufactured by Taoka Chemical Co., Ltd., and the like.
Tamanor (registered trademark) 100S, 200N, 510, 521, 526, 586, 2800, 7509, etc., manufactured by Arakawa Chemical Industries, Ltd.

These alkylphenol resins can be used alone or in combination of two or more.
As alkylphenol-based resins, there are also known alkylphenol-based resins that function as crosslinking agents for rubbers such as EPDM, such as TACKIROL 201, 250-I, 250-III, AP, and V-200 manufactured by Taoka Chemical Co., Ltd. (Patent Documents 2 and 3, etc.).
However, these alkylphenol resins have their properties, such as acid value, adjusted or are modified with halogens or the like, and none of them function as tackifiers. Even if they are blended, they cannot achieve the same effects as the present invention described above.

Furthermore, there may be cases where the ethylene-α-olefin-diene copolymer rubber cannot be crosslinked satisfactorily due to competition with the sulfur-based crosslinking agent. Therefore, in the present invention, alkylphenol-based resins that function as crosslinking agents are not included (excluded).
As described above, the proportion of the alkylphenol resin is limited to 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of rubber.

If the proportion of alkylphenol-based resin is below this range, even if a sulfur-based crosslinking agent is used as the crosslinking component, the initial friction coefficient of the roller body of the paper feed roller, etc., may not be sufficiently increased to a range where paper feeding problems do not occur even after repeated paper feeding.
On the other hand, if the proportion of the alkylphenol resin exceeds the above range, not only will no further effect be obtained, but the processability of the rubber composition for paper feeding members may also decrease.

That is, it may become difficult to knead each component in a kneader, remove it from the kneader, or mold it into the shape of the roller body in order to prepare the rubber composition for the paper feeding member.
In contrast, by setting the proportion of alkylphenol-based resin within the above range, it is possible to maintain good processability while sufficiently increasing the initial friction coefficient of the roller body of the paper feed roller, etc., to a range where paper feeding problems do not occur even when paper feeding is repeated.

In order to further improve this effect, the proportion of the alkylphenol resin is preferably at least 3 parts by mass, and more preferably at least 4 parts by mass, per 100 parts by mass of the total amount of rubber, even within the above range, and is preferably at most 13 parts by mass, and more preferably at most 12 parts by mass.
Filler
The rubber composition for the paper feed member may contain a filler in order to improve the mechanical strength of the paper feed member or to reduce the compounding cost of the rubber compound without affecting the properties of the paper feed member.

Examples of the filler include one or more of carbon black, calcium carbonate, zinc oxide, silica, clay, talc, magnesium carbonate, aluminum hydroxide, titanium oxide, and the like.
In particular, in order to reduce the compounding cost of the rubber compound without affecting the characteristics of the roller body, it is preferable to use one or more of carbon black, calcium carbonate, clay, talc, magnesium carbonate, aluminum hydroxide, etc.

Furthermore, a small amount of carbon black may be used as a filler that also functions as a colorant together with one or more of calcium carbonate, clay, talc, magnesium carbonate, aluminum hydroxide, and the like.
When the rubber contains an oil-extended rubber such as oil-extended EPDM, the proportion of the filler will vary depending on the amount of oil extension, but is preferably 20 parts by mass or more, particularly 23 parts by mass or more, per 100 parts by mass of the total rubber, and is preferably 30 parts by mass or less, particularly 27 parts by mass or less.

When the rubber does not contain oil-extended rubber, the amount is preferably at least 3 parts by mass, particularly preferably at least 5 parts by mass, and is preferably at most 15 parts by mass, particularly preferably at most 10 parts by mass, per 100 parts by mass of the total rubber.
The proportion of carbon black as a filler also functioning as a colorant is preferably at least 0.1 part by mass, particularly preferably at least 0.3 part by mass, and not more than 1 part by mass, particularly preferably not more than 0.7 part by mass, per 100 parts by mass of the total amount of rubber.

<Other Ingredients>
The rubber composition may further contain an appropriate amount of components that are generally blended as additives in rubber compositions, such as a crosslinking aid, an antiaging agent, a co-crosslinking agent, a pigment, a plasticizer, a processing aid, and a peptizer, within a range that does not impair the effects of the present invention.
(Crosslinking assistant)
Among the above crosslinking assistants, examples of the crosslinking assistant include metal compounds such as zinc oxide; fatty acids such as stearic acid, oleic acid, cottonseed fatty acid, and other conventionally known crosslinking assistants, and one or more of these may be used.

The proportion of the crosslinking aid is preferably at least 0.1 part by mass, particularly preferably at least 0.3 part by mass, and is preferably at most 8 parts by mass, particularly preferably at most 6 parts by mass, per 100 parts by mass of the total amount of rubber.
As described above, the rubber composition for paper feed members of the present invention can be used as a material for forming various paper feed members for feeding sheets, such as paper feed rollers and separation pads.

In particular, it can be suitably used as a material for forming a paper feed roller, which requires a friction coefficient in a range higher than that of a separation pad.
<Paper feed roller>
FIG. 1 is an enlarged perspective view of a portion of a paper feed roller according to an embodiment of the present invention.

Referring to FIG. 1, a paper feed roller 1 of this embodiment includes a roller body 2 formed by molding the above-mentioned rubber composition for paper feed members into a cylindrical shape and crosslinking it.
A through hole 3 having a circular cross section is provided in the center of the roller body 2, and a cylindrical shaft 4 which is connected to a drive system (not shown) is inserted into the through hole 3 and fixed thereto.
In the illustrated example, the outer peripheral surface 5 of the roller body 2 that comes into contact with the paper is formed into a cylindrical shape that is concentric with the through hole 3 and the shaft 4 .

The roller body 2 and the shaft 4 are fixed to each other so as not to spin freely, for example by press-fitting the shaft 4, whose outer diameter is larger than the inner diameter of the through hole 3, into the through hole 3 of the roller body 2.
In other words, a certain amount of idling torque (the limit torque at which idling does not occur) is ensured between the two by the interference based on the diameter difference between the two.

The shaft 4 is made of, for example, a metal, a ceramic, a hard resin, or the like.
If necessary, a plurality of roller bodies 2 may be fixed to a single shaft 4 at a plurality of positions.
The roller body 2 is manufactured by molding a rubber composition for a paper feed member into a cylindrical shape, for example by extrusion molding, and then cross-linking it by a press cross-linking method, or by molding it into a cylindrical shape and cross-linking it by transfer molding.

At any point in the above manufacturing process, the outer circumferential surface 5 of the roller body 2 may be polished to a predetermined surface roughness, knurled, textured, or the like, as necessary.
In addition, both ends of the roller body 2 may be cut so that the outer circumferential surface 5 has a predetermined width.
The roller body 2 may be formed in a two-layer structure having an outer layer on the outer circumferential surface 5 side and an inner layer on the through hole 3 side.

In this case, it is preferable that at least the outer layer is formed from a crosslinked product of the rubber composition for paper feeding members of the present invention described above.
However, in consideration of simplifying the structure, improving productivity, and reducing manufacturing costs, it is preferable that the roller body 2 has a single-layer structure made of a cross-linked product of the rubber composition for paper feeding members of the present invention, as shown in FIG. 1.

The roller body 2 may also have a porous structure.
However, in order to increase the tensile strength, improve the wear resistance, and reduce the compression set, thereby making it less likely that dents will occur due to deformation even if contact at one point continues for a relatively long period of time, it is preferable that the roller body 2 has a substantially non-porous structure.
In order to ensure good paper feeding using the paper feed roller 1, it is preferable that the roller body 2 has a type A durometer hardness of A55 or less, particularly A50 or less.

In addition, in consideration of improving the wear resistance and reducing the compression set, it is preferable that the roller body 2 has a type A durometer hardness of A25 or more, particularly A30 or more.
Depending on the application of the paper feed roller 1, the through hole 3 may be provided at a position eccentric to the center of the roller body 2.

Furthermore, the outer circumferential surface 5 of the roller body 2 may not be cylindrical but may have an irregular shape, for example, a shape in which a part of the cylindrical outer circumferential surface 5 is cut out into a flat shape.
To manufacture a paper feed roller 1 having a roller body 2 of these irregular shapes, the roller body 2 of the irregular shape may be directly molded using the manufacturing method described above, or the roller body 2 molded into a cylindrical shape may be post-processed to give it the irregular shape.

Furthermore, the roller body 2 may be deformed into the irregular shape by pressing the shaft 4, which has a deformed shape corresponding to the irregular shape of the roller body 2, into the through hole 3 of the roller body 2 formed into a cylindrical shape.
In this case, polishing, knurling, texturing, etc. of the outer peripheral surface 5 can be performed on the cylindrical outer peripheral surface 5 before deformation, thereby improving workability.
The paper feed roller of the present invention can be incorporated in various office automation devices that utilize electrophotography, such as laser printers, electrostatic copying machines, plain paper facsimile machines, or combination machines of these.

The paper feed roller of the present invention can also be incorporated in, for example, an inkjet printer or an automated teller machine (ATM).
The paper feed roller of the present invention rotates while in contact with sheets of paper, plastic film, or the like, and transports the paper by friction, and can be used, for example, as a paper feed roller, transport roller, platen roller, paper discharge roller, and the like.

The present invention will be further described based on examples and comparative examples, but the configuration of the present invention is not limited to these examples.
Example 1
(Preparation of Rubber Composition)
The rubber used was 200 parts by mass of oil-extended EPDM (Esprene 670F, manufactured by Sumitomo Chemical Co., Ltd., amount of oil extension: 100 phr) (rubber as solid content: 100 parts by mass).

200 parts by mass of this oil-extended EPDM was mixed with 12 parts by mass of an alkylphenol resin (Tamanol 510 manufactured by Arakawa Chemical Industries, Ltd., hereinafter sometimes abbreviated as "alkylphenol resin I") and the following components, and kneaded using a 3L kneader and an open roll.

The components in Table 1 are as follows, and the parts by mass in the table are parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content).
Filler i: Carbon black HAF (Seat (registered trademark) 3 manufactured by Tokai Carbon Co., Ltd.)
Filler ii: Heavy calcium carbonate (BF300 manufactured by Bihoku Funka Kogyo Co., Ltd.)
Crosslinking aid i: zinc oxide type 2 [manufactured by Mitsui Mining & Smelting Co., Ltd.]
Crosslinking aid II: Stearic acid (Tsubaki, manufactured by NOF Corp.)
Next, while continuing the kneading, the following crosslinking components were added and further kneaded to prepare a rubber composition for paper feeding members.

The components in Table 2 are as follows, and the parts by mass in the table are parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content).
Crosslinking agent: Powdered sulfur (sulfur-based crosslinking agent, manufactured by Tsurumi Chemical Industry Co., Ltd.)
Accelerator TOT: Tetrakis(2-ethylhexyl)thiuram disulfide (Noccela (registered trademark) TOT-N, a thiuram-based accelerator, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
Accelerator DM: Di-2-benzothiazolyl disulfide (Noccela DM, a thiazole-based accelerator, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
(Manufacturing of paper feed rollers)
The above-mentioned rubber composition for paper feed members was transfer molded into a cylindrical shape under conditions of 165°C x 30 minutes, and with a shaft 4 with an outer diameter of 12 mm pressed into the through hole 3, it was polished using a cylindrical grinding machine to an outer diameter of 21 mm, and then cut to a width of 25 mm to produce a paper feed roller 1 equipped with a cylindrical roller body 2 (see Figure 1).

Example 2
A rubber composition for a paper feed member was prepared in the same manner as in Example 1, except that the amount of alkylphenol resin I was 8 parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content), and a paper feed roller 1 was manufactured.
Example 3
A rubber composition for a paper feed member was prepared in the same manner as in Example 1, except that 4 parts by mass of TACKIROL 160 (an alkylphenol-acetaldehyde resin, hereinafter sometimes abbreviated as "alkylphenol resin II") manufactured by Taoka Chemical Co., Ltd. was blended per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content) instead of alkylphenol resin I, and paper feed roller 1 was manufactured.

Comparative Example 1
A rubber composition for a paper feed member was prepared in the same manner as in Example 1, except that the alkylphenol resin I was not blended, and a paper feed roller 1 was manufactured.
Comparative Example 2
A rubber composition for a paper feed member was prepared in the same manner as in Example 1, except that the amount of alkylphenol resin I was 1 part by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content), and a paper feed roller 1 was manufactured.

Comparative Example 3
A rubber composition for a paper feed member was prepared in the same manner as in Example 1, except that the amount of alkylphenol resin I was 10 parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content), and 4 parts by mass of a peroxide crosslinking agent (dicumyl peroxide, Percumyl (registered trademark) D manufactured by NOF Corporation) was blended per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content) instead of a sulfur-based crosslinking agent, and accelerators TOT and DM were not blended. A paper feed roller 1 was manufactured using the same rubber composition for a paper feed member as in Example 1, except that the amount of alkylphenol resin I was 10 parts by mass per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content), and 4 parts by mass of a peroxide crosslinking agent (dicumyl peroxide, Percumyl (registered trademark) D manufactured by NOF Corporation) was blended per 200 parts by mass of oil-extended EPDM (100 parts by mass of rubber as solid content) instead of a sulfur-based crosslinking agent, and accelerators TOT and DM were not blended.

In addition, in the case of crosslinking using a peroxide crosslinking agent, the two crosslinking assistants (zinc oxide and stearic acid) are not necessary, but in Comparative Example 3, the same amounts are blended for comparative evaluation with each of the Examples and Comparative Examples.
<Hardness test>
The rubber compositions prepared in the Examples and Comparative Examples were crosslinked by press at 160° C. for 30 minutes to form a sheet having a thickness of 2 mm, and three such sheets were stacked to form test specimens.

Using this test piece, the hardness was measured in an environment of 23° C. in accordance with the measurement method described in Japanese Industrial Standards JIS K6253-3 _{: 2012} “Vulcanized rubber and thermoplastic rubber - Determination of hardness - Part 3: Durometer hardness”, and the value after 3 seconds was read and determined as the type A durometer hardness.
Tensile Test
The rubber compositions prepared in the Examples and Comparative Examples were press-crosslinked at 160°C for 30 minutes to form sheets of 2 mm thickness, which were then punched out to prepare dumbbell-shaped No. 3 test pieces as specified in Japanese Industrial Standard JIS K6251 _:2017 "Vulcanized rubber and thermoplastic rubber -- Determination of tensile properties". Tensile tests as specified in the same standard were carried out in an environment of 23°C to determine the tensile strength T (MPa) and elongation at break _Eb (%).

<Friction coefficient test>
As shown in FIG. 2, the roller body 2 of the prepared paper feed roller 1 was pressed against a piece of paper 7 (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) measuring 60 mm in width and 210 mm in length, which was placed on a horizontally placed polytetrafluoroethylene (PTFE) plate 6, while applying a vertical load W (=300 gf).

Next, in an environment of a temperature of 23° C. and a relative humidity of 55%, the roller body 2 was rotated at 200 rpm in the direction indicated by the dashed arrow R, and the conveying force F (gf) applied to the load cell 8 connected to one end of the paper 7 was measured.
Next, from the measured conveying force F and the vertical load W (= 300 gf), the following formula (1):
Friction coefficient μ = F(gf) / W(gf) (1)
The friction coefficient μ was calculated by

<Wear resistance test>
As in the friction coefficient test, as shown in FIG. 2, the roller body 2 of the paper feed roller 1 was pressed against a piece of paper 7 (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) measuring 60 mm in width and 210 mm in length, which was placed on a horizontally placed PTFE plate 6, while applying a vertical load W (=500 gf).

Next, the roller body 2 was rotated continuously for 10 minutes at 200 rpm in the direction indicated by the dashed-dotted arrow R in an environment of a temperature of 23° C. and a relative humidity of 55%.
Next, the mass (post-wear mass) M ₁ (g) of the roller body 2 after the continuous rotation is weighed, and the post-wear mass M ₁ (g) and the initial mass M 0 (g) of the roller body 2 weighed before the continuous rotation are used to calculate the mass M ₁ (g) of the roller body 2 according to the following formula (2):
Mass loss rate ΔM (%) = (M ₀ - M ₁ )/M ₀ ×100 (2)
The mass reduction rate ΔM was calculated by the following.

The smaller the mass reduction rate ΔM, the more excellent the wear resistance of the roller body 2 can be evaluated.
The results are shown in Table 3.

The results of Examples 1 to 3 and Comparative Examples 1 and 3 in Table 3 show that by crosslinking rubber containing oil-extended EPDM with a sulfur-based crosslinking agent, the effect of compounding an alkylphenol-based resin as a tackifier is improved, and the initial friction coefficient of the roller body of the paper feed roller as a paper feed member can be sufficiently increased to a range where paper feed failure does not occur when paper is repeatedly fed, and the deterioration of the wear resistance of the roller body can also be suppressed.

Furthermore, from the results of Examples 1 to 3 and Comparative Example 2, it was found that in order to obtain the above-mentioned effects, the proportion of the alkylphenol-based resin needs to be 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of rubber as solid content in the oil-extended EPDM.
Furthermore, the results of Examples 1 to 3 show that various alkylphenol resins capable of functioning as a tackifier can be used as the alkylphenol resin.

Example 4
As the rubber, 100 parts by mass of non-oil-extended EPDM (Esprene 505A manufactured by Sumitomo Chemical Co., Ltd.) was used.
100 parts by mass of the non-oil-extended EPDM was blended with 5 parts by mass of alkylphenol resin I (Tamanol 510 manufactured by Arakawa Chemical Industries, Ltd.) and the following components, and the mixture was kneaded using a 3L kneader and an open roll.

The components in Table 4 are the same as those in Table 1, and the parts by mass in the table are parts by mass per 100 parts by mass of un-oil-extended EPDM.
Next, while continuing the kneading, the following crosslinking components were added and further kneaded to prepare a rubber composition for paper feeding members.

The components in Table 2 are the same as those in Table 2, and the parts by mass in the table are parts by mass per 100 parts by mass of non-oil-extended EPDM.
(Manufacturing of paper feed rollers)
The above-mentioned rubber composition for paper feed members was transfer molded into a cylindrical shape under conditions of 165°C x 30 minutes, and with a shaft 4 with an outer diameter of 12 mm pressed into the through hole 3, it was polished using a cylindrical grinding machine to an outer diameter of 21 mm, and then cut to a width of 25 mm to produce a paper feed roller 1 equipped with a cylindrical roller body 2 (see Figure 1).

Example 5
A rubber composition for a paper feed member was prepared in the same manner as in Example 4, except that alkylphenol resin II (TACKIROL 160, an alkylphenol-acetaldehyde resin manufactured by Taoka Chemical Co., Ltd., mentioned above) was blended in an amount of 5 parts by mass per 100 parts by mass of non-oil-extended EPDM instead of alkylphenol resin I, and paper feed roller 1 was manufactured.

Comparative Example 4
A rubber composition for a paper feed member was prepared in the same manner as in Example 4, except that the alkylphenol resin I was not blended, and a paper feed roller 1 was manufactured.
Comparative Example 5
A peroxide crosslinking agent (the above-mentioned dicumyl peroxide, Percumyl D manufactured by NOF Corp.) was used as the crosslinking agent instead of the sulfur-based crosslinking agent in an amount of 3 parts by mass per 100 parts by mass of non-oil-extended EPDM, and the accelerators TOT and DM were not used. In the same manner as in Example 4, except for this, a rubber composition for a paper feed member was prepared, and a paper feed roller 1 was manufactured.

In addition, in the case of crosslinking using a peroxide crosslinking agent, as described above, the two crosslinking assistants (zinc oxide and stearic acid) are not necessary, but in Comparative Example 5, the same amount is blended for comparative evaluation with each of the Examples and Comparative Examples.
The rubber compositions prepared in the Examples and Comparative Examples, and the paper feed roller 1 produced were subjected to the above-mentioned tests to evaluate their properties.

The results are shown in Table 6.

From the results of Examples 4 and 5 and Comparative Examples 4 and 5 in Table 6, it was found that the same results as those of the previous Examples and Comparative Examples using oil-extended EPDM were obtained even in systems using non-oil-extended EPDM.
That is, from the results of Examples 4 and 5 and Comparative Examples 4 and 5, it was found that by crosslinking rubber containing non-oil-extended EPDM with a sulfur-based crosslinking agent, the effect of blending an alkylphenol resin as a tackifier is improved and the initial friction coefficient of the roller body of the paper feed roller as a paper feeding member can be sufficiently increased to a range where paper feeding problems do not occur when paper feeding is repeated, and the decrease in the wear resistance of the roller body can also be suppressed.

Moreover, from the results of Examples 4 and 5, it was found that in order to obtain the above-mentioned effects, the proportion of the alkylphenol resin must be 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of non-oil-extended EPDM.
Furthermore, the results of Examples 4 and 5 show that various alkylphenol resins capable of functioning as a tackifier can be used as the alkylphenol resin.

REFERENCE SIGNS LIST 1 Paper feed roller 2 Roller body 3 Through hole 4 Shaft 5 Outer circumferential surface 6 Plate 7 Paper 8 Load cell F Conveying force W Vertical load

Claims (4)

The present invention comprises a rubber containing an ethylene-α-olefin copolymer rubber, a cross-linking component for cross-linking the rubber , a tackifier , and a filler ,
The ethylene-α-olefin copolymer rubber is a copolymer rubber of ethylene, an α-olefin, and a diene,
The cross- linking component includes at least a sulfur-based cross-linking agent ,
The tackifier contains an alkylphenol resin (excluding alkylphenol resins that function as crosslinking agents) in an amount of 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the total amount of the rubber,
The rubber composition for a paper-feeding member contains the filler in an amount of 3 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the total amount of the rubber . The rubber composition for paper feed members according to claim 1, wherein the ethylene-α-olefin copolymer rubber is an ethylene-propylene-diene copolymer rubber. 3. The rubber composition for a paper feeding member according to claim 1 , wherein the crosslinking component uses 0.5 parts by mass or more and 2 parts by mass or less of sulfur as the sulfur-based crosslinking agent per 100 parts by mass of the total amount of the rubber. A paper feed roller comprising a roller body made of a crosslinked product of the rubber composition for paper feed members according to any one of claims 1 to 3 .

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