CN118852749A

CN118852749A - Rubber composition for sheet conveying roller and sheet conveying roller

Info

Publication number: CN118852749A
Application number: CN202311795225.6A
Authority: CN
Inventors: 滨洼真司; 藤井良辅
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2023-04-27
Filing date: 2023-12-25
Publication date: 2024-10-29

Abstract

The application provides a rubber composition for a sheet conveying roller, which can be manufactured with excellent friction coefficient in a rubber composition containing the same base rubber and a cross-linking agent. A rubber composition for a sheet conveying roller, characterized by comprising a base rubber and a petroleum resin, wherein the base rubber comprises a diene rubber, and the content of the diene rubber is 50 mass% or more in 100 mass% of the base rubber.

Description

Rubber composition for sheet conveying roller and sheet conveying roller

Technical Field

The present invention relates to a rubber composition for forming a sheet conveying roller.

Background

Various sheet conveying rollers are incorporated in sheet conveying mechanisms in machines such as electrostatic copiers, laser printers, plain paper facsimile machines, image forming apparatuses such as composite apparatuses thereof, inkjet printers, document processing apparatuses for scanning and sorting bills, and the like. The sheet conveying roller rotates while contacting a sheet such as paper or plastic film, and conveys the sheet by friction.

As a material of the sheet conveying roller, ethylene-propylene-diene monomer copolymer (EPDM) is often used from the viewpoints of friction coefficient, environmental resistance (for example, ozone resistance), and cost. In recent years, various types of sheets used in image forming apparatuses and the like are used, and there are cases where a high friction coefficient is required for a sheet conveying roller.

Therefore, a technique for increasing the friction coefficient of a roller using EPDM has been proposed. For example, patent document 1 describes a paper feed roller comprising a roller body formed of a rubber composition for forming the roller body of the paper feed roller, wherein a non-oil-extended ethylene-propylene-diene rubber having an ethylene content of 55% or more and 72% or less and an oil-extended ethylene-propylene-diene rubber are contained as rubber components, and the proportion of the non-oil-extended ethylene-propylene-diene rubber is 20 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the total amount of the rubber (see patent document 1 (claim 5, table 1)).

In addition, a technique has been proposed in which the friction coefficient of the roller is increased by changing the main body of the base rubber to isoprene rubber or natural rubber. For example, patent document 2 describes a paper feed roller including a roller main body formed of a crosslinked product of a rubber composition containing at least one isoprene-based rubber (excluding epoxidized natural rubber) selected from the group consisting of isoprene rubber and natural rubber in a proportion of 55 parts by mass or more in 100 parts by mass of the total amount of rubber (see patent document 2 (claims 1, table 1)).

[ Prior Art literature ]

[ Patent literature ]

[ Patent document 1] JP patent publication 2020-2271

[ Patent document 2] JP-A2021-91549

Disclosure of Invention

[ Problem to be solved by the invention ]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a rubber composition capable of producing a sheet conveying roller excellent in friction coefficient, from among rubber compositions containing the same base rubber and a crosslinking agent.

[ Means for solving the problems ]

The rubber composition for a sheet conveying roller of the present invention capable of solving the above-mentioned problems is characterized by comprising a base rubber and a petroleum resin, wherein the base rubber comprises a diene rubber, and the content of the diene rubber is 50 mass% or more in 100 mass% of the base rubber.

[ Effect of the invention ]

According to the present invention, a rubber composition that can produce a sheet conveying roller excellent in friction coefficient can be obtained from a rubber composition containing the same base rubber and a crosslinking agent.

Drawings

Fig. 1 is a perspective view showing an example of a sheet conveying roller according to the present invention.

Fig. 2 is a schematic diagram illustrating a method of measuring a friction coefficient.

[ Reference numerals ]

1: Sheet conveying roller, 2: roller body, 3: through hole, 4: shaft (shaft), 10: plate, 11: paper, 12: load sensor (load cell)

Detailed Description

The rubber composition for a sheet conveying roller (hereinafter, may be simply referred to as "rubber composition") of the present invention is characterized by: the base material rubber comprises a base material rubber and a petroleum resin, wherein the base material rubber comprises a diene rubber, and the content of the diene rubber is 50 mass% or more in 100 mass% of the base material rubber.

In the rubber composition for a sheet conveying roller of the present invention, the friction coefficient of the obtained sheet conveying roller can be increased by using a diene rubber as a main component of the base rubber. Further, by adding a petroleum resin to the rubber composition for a sheet conveying roller, the friction coefficient of the resulting sheet conveying roller can be further improved.

(Base rubber)

The rubber composition contains a diene rubber as a base rubber. The diene rubber may be used alone or in combination of at least 2 kinds.

Examples of the diene rubber include isoprene rubber, natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and chloroprene rubber.

(Isoprene rubber (IR))

As the isoprene rubber, any of various polymers having a polyisoprene structure, which artificially reproduces the structure of natural rubber, may be used. In particular, in view of improving workability in preparing a rubber composition, forming a roll body by crosslinking it after shaping it into a roll body, and the like, isoprene rubber which is semi-solid or solid at ordinary temperature (5 to 35 ℃) before crosslinking is preferable.

(Natural rubber (NR))

Examples of the natural rubber include various natural rubbers having an arbitrary mooney viscosity such as SMR (standard malaysia rubber), SVR (standard vietnam rubber), SIR (standard indonesia rubber), STR (standard thailand rubber), SSR (standard singapore rubber), SCR (standard cassitan rubber), and various grades of sheet rubber such as rib smoke film (Ribbed Smoked Sheet), white crepe (WHITE CREPE), pallium rubber (PALE CREPE), rubber dome (estate brown crepe), hybrid crepe (compo crepe), thin brown crepe (thin brown crepe), and thick brown crepe (thick brown crepe) among grades of varieties classified according to green sheets.

As the natural rubber, modified natural rubber such as deproteinized natural rubber, hydrogenated natural rubber, and grafted natural rubber can be used.

(Styrene-butadiene rubber (SBR))

The styrene-butadiene rubber is a copolymer of styrene and 1, 3-butadiene, and any of various styrene-butadiene rubbers having crosslinkability may be used. The styrene-butadiene rubber may be a styrene-butadiene rubber obtained by an emulsion polymerization method, a styrene-butadiene rubber obtained by a solution polymerization method, or the like, and a styrene-butadiene rubber obtained by an emulsion polymerization method is preferable.

As the styrene-butadiene rubber, any of high-styrene type, medium-styrene type and low-styrene type styrene-butadiene rubbers classified according to styrene content may be used. The styrene content of the styrene-butadiene rubber is preferably 15 mass% or more, more preferably 20 mass% or more, and further preferably 45 mass% or less, more preferably 35 mass% or less.

The content of the diene rubber in 100 mass% of the base rubber is 50 mass% or more, preferably 55 mass% or more, and more preferably 60 mass% or more, and the base rubber may contain only the diene rubber. When the content of the diene rubber in the base rubber is 50 mass% or more, the friction coefficient of the obtained sheet conveying roller can be increased.

The rubber composition preferably contains isoprene rubber and/or natural rubber as the diene rubber. In this case, the total content of the isoprene rubber and the natural rubber is preferably 30 mass% or more, more preferably 40 mass% or more, in 100 mass% of the base rubber, and only isoprene rubber and/or natural rubber may be contained as the base rubber.

(Other rubber component)

The base rubber may contain, as the base rubber, a rubber component other than the diene rubber to such an extent that the effect of the present invention is not impaired.

Examples of the other rubber component include non-diene rubbers such as ethylene- α -olefin copolymers, ethylene-vinyl acetate copolymers, epichlorohydrin-based rubbers, acrylic rubbers, butyl rubbers, and silicone rubbers. These other rubber components may be used alone or in combination of 2 or more.

The base rubber may further contain an ethylene-alpha-olefin copolymer and/or an ethylene-vinyl acetate copolymer. The base rubber is improved in ozone resistance of the sheet conveying roller obtained by further containing an ethylene-alpha-olefin copolymer and/or an ethylene-vinyl acetate copolymer.

When the rubber composition contains an ethylene- α -olefin copolymer and/or an ethylene-vinyl acetate copolymer as a base rubber, the total content of the ethylene- α -olefin copolymer and the ethylene-vinyl acetate copolymer is preferably 25 mass% or more, more preferably 30 mass% or more, preferably less than 50 mass%, and still more preferably 40 mass% or less, based on 100 mass% of the base rubber.

(Ethylene-alpha-olefin copolymer)

The ethylene-alpha-olefin copolymer is a copolymer containing at least ethylene and an alpha-olefin as constituent components. In addition, the ethylene-alpha-olefin copolymer further comprises: ethylene-alpha-olefin-diene copolymers having double bonds incorporated in the main chain by adding small amounts of diene components to the ethylene and the alpha-olefin.

Examples of the α -olefin include propylene, 1-butene, 1-hexene, and 1-octene.

Examples of the diene component include Ethylidene Norbornene (ENB), 1, 4-hexadiene (1, 4-HD), and Dicyclopentadiene (DCP), and ethylidene norbornene is preferable.

Examples of the ethylene- α -olefin copolymer include an ethylene-propylene copolymer (EPM), an ethylene-butene copolymer (EBR), and an ethylene-octene copolymer (EOR). The ethylene- α -olefin-diene copolymer may be an ethylene-propylene-diene copolymer (EPDM), an ethylene-butene-diene copolymer (EBDM), an ethylene-propylene-butene-diene copolymer (EPBDM), or the like.

(Ethylene-vinyl acetate copolymer)

The ethylene-vinyl acetate copolymer is a copolymer of ethylene and vinyl acetate. The ethylene-vinyl acetate copolymer has a vinyl acetate content of 10 mass% or more, preferably 14 mass% or more, and 50 mass% or less, preferably 46 mass% or less.

(Petroleum resin)

The rubber composition contains a petroleum resin. By containing the petroleum resin, the friction coefficient of the sheet conveying roller can be further improved. The petroleum resin may be used alone or in combination of 1 or 2 or more.

The petroleum resin is a resin obtained by polymerizing or copolymerizing a petroleum fraction obtained as a by-product when an olefin such as ethylene is produced by thermally decomposing a petroleum such as naphtha. The petroleum resin may not be entirely a petroleum fraction, but may contain chemically synthesized unsaturated compounds.

Examples of the petroleum fraction include aliphatic olefins having 4 to 10 carbon atoms, aliphatic diolefins having 4 to 10 carbon atoms, and aromatic compounds having 8 or more carbon atoms and having an ethylenically unsaturated bond.

Examples of the aliphatic olefins having 4 to 10 carbon atoms include butene, pentene, hexene, heptene and the like. Examples of the aliphatic diolefins having 4 to 10 carbon atoms include butadiene, pentadiene, isoprene, cyclopentadiene, dicyclopentadiene, methylpentadiene and the like. Examples of the aromatic compound having 8 or more carbon atoms and having an ethylenically unsaturated bond include styrene, α -methylstyrene, β -methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, ethylindene, and the like.

Examples of the chemically synthesized unsaturated compound include cyclopentadiene and dicyclopentadiene (DCPD).

As the petroleum resin, there may be mentioned: aliphatic petroleum resins obtained by polymerizing aliphatic olefins and/or aliphatic dienes; an aromatic petroleum resin obtained by polymerizing an aromatic compound having an ethylenically unsaturated bond; aliphatic-aromatic copolymer-based petroleum resins obtained by copolymerizing aliphatic olefins and/or aliphatic dienes with aromatic compounds having an ethylenically unsaturated bond; dicyclopentadiene petroleum resins obtained by polymerizing cyclopentadiene or dicyclopentadiene; aliphatic-dicyclopentadiene copolymer-based petroleum resins obtained by polymerizing aliphatic olefins and/or aliphatic dienes with cyclopentadiene and dicyclopentadiene; an aromatic-dicyclopentadiene copolymer-based petroleum resin obtained by copolymerizing an aromatic compound having an ethylenically unsaturated bond with cyclopentadiene or dicyclopentadiene, or an aliphatic-aromatic-dicyclopentadiene copolymer-based petroleum resin obtained by polymerizing an aliphatic olefin and/or an aliphatic diene with an aromatic compound having an ethylenically unsaturated bond, with cyclopentadiene or dicyclopentadiene; and styrene resins obtained by polymerizing styrene compounds (styrene, α -methylstyrene, β -methylstyrene).

Further, as the petroleum resin, a hydrogenated petroleum resin obtained by hydrogenating a polymer obtained by polymerizing the petroleum fraction or the chemically synthesized unsaturated compound may be used. By hydrogenation, the double bonds in the molecule are hydrogenated. The hydride may be any of a fully hydrogenated petroleum resin in which all of the double bonds in the molecule are hydrogenated, and a partially hydrogenated petroleum resin in which part of the double bonds in the molecule are hydrogenated.

As the hydrogenated petroleum resin, there may be mentioned: hydrogenated aliphatic petroleum resin obtained by hydrogenating an aliphatic petroleum resin; hydrogenated aromatic petroleum resin obtained by hydrogenating aromatic petroleum resin; hydrogenated aliphatic-aromatic copolymer-based petroleum resin obtained by hydrogenating aliphatic-aromatic copolymer-based petroleum resin; hydrogenated dicyclopentadiene petroleum resin obtained by hydrogenating dicyclopentadiene petroleum resin; hydrogenated aliphatic-dicyclopentadiene copolymer-based petroleum resin obtained by hydrogenating aliphatic-dicyclopentadiene copolymer-based petroleum resin; hydrogenated aromatic-dicyclopentadiene copolymer-based petroleum resin obtained by hydrogenating aromatic-dicyclopentadiene copolymer-based petroleum resin; hydrogenated aliphatic-aromatic-dicyclopentadiene copolymer-based petroleum resins obtained by hydrogenating aliphatic-aromatic-dicyclopentadiene copolymer-based petroleum resins, and the like.

The petroleum resin is preferably 1 or more petroleum resins selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, dicyclopentadiene petroleum resins, aliphatic-dicyclopentadiene copolymer petroleum resins, aromatic-dicyclopentadiene copolymer petroleum resins, aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, hydrogenated aliphatic-aromatic copolymer petroleum resins, hydrogenated dicyclopentadiene petroleum resins, hydrogenated aliphatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, and styrene petroleum resins.

The softening point of the petroleum resin is preferably 50 ℃ or higher, more preferably 60 ℃ or higher, further preferably 70 ℃ or higher, and further preferably 150 ℃ or lower, more preferably 140 ℃ or lower, further preferably 130 ℃ or lower. When the softening point is 50 ℃ or higher, the handling during storage and measurement is easy, and when the softening point is 150 ℃ or lower, the resin is easy to soften and knead during kneading. Further, the softening point of the petroleum resin was measured according to the softening point of 7.7 of JIS K6220-1 (2015).

The content of the petroleum resin in the rubber composition is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, further preferably 2.0 parts by mass or more, and further preferably 15 parts by mass or less, more preferably 13 parts by mass or less, further preferably 12 parts by mass or less, based on 100 parts by mass of the base rubber. When the content of the petroleum resin is 1.0 part by mass or more, the friction coefficient of the sheet conveying roller is further increased, and when the content of the petroleum resin is 15 parts by mass or less, adhesion to the inner wall of the apparatus can be suppressed during kneading, and the processability is improved.

(Crosslinking agent)

The rubber composition preferably contains a crosslinking agent. By containing the crosslinking agent, the abrasion resistance of the resulting sheet conveying roller is further improved.

As the crosslinking agent, any of a sulfur-based crosslinking agent, an organic peroxide, and a resin crosslinking agent can be used. In the case where there is concern about the decrease in the friction coefficient of the roller due to the blooming of the sulfur-based crosslinking agent, an organic peroxide is preferably used as the crosslinking agent.

The sulfur-based crosslinking agent may be elemental sulfur or a sulfur carrier (sulfur-donor) compound. The elemental sulfur may be powdered sulfur, precipitated sulfur, colloidal sulfur, or insoluble sulfur. Examples of the sulfur carrier compound include 4,4' -dithiodimorpholine and the like. The sulfur-based crosslinking agent may be used alone or in combination of 2 or more.

When the sulfur-based crosslinking agent is compounded, the content of the sulfur-based crosslinking agent in the rubber composition is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, further preferably 0.5 part by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, per 100 parts by mass of the base rubber.

Examples of the organic peroxide include dicumyl peroxide, α' -bis (t-butylperoxy-m-diisopropyl) benzene, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, and 1, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane. The organic peroxide may be used alone or in combination of 2 or more.

When the organic peroxide is compounded, the content of the organic peroxide in the rubber composition is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 1.0 part by mass or more, preferably 15 parts by mass or less, more preferably 10 parts by mass or less, further preferably 8 parts by mass or less, per 100 parts by mass of the base rubber.

Examples of the resin crosslinking agent include alkylphenol resins such as alkylphenol resins, thermoreactive phenol resins, phenol-diol resins, bisphenol resins, and thermoreactive bromomethyl alkylated phenol resins.

(Crosslinking accelerator)

When a sulfur-based crosslinking agent is used as the crosslinking agent, the rubber composition may further contain a crosslinking accelerator. As the crosslinking accelerator, any of an inorganic accelerator and an organic accelerator can be used. Examples of the inorganic accelerator include slaked lime, magnesium oxide (MgO), and litharge (litharge) (PbO). Examples of the organic accelerator include thiazole-based accelerators, thiuram-based accelerators, sulfenamide-based accelerators, and dithiocarbamate-based accelerators. The crosslinking accelerator may be used alone or in combination of 2 or more. As the crosslinking accelerator in combination with the sulfur-based crosslinking agent, a thiazole-based accelerator and a thiuram-based accelerator are preferably used in combination.

Examples of the thiazole-based accelerator include 2-mercaptobenzothiazole, 2 '-dibenzothiazyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole, and 2- (4' -morpholinodithio) benzothiazole, and preferably di-2-benzothiazolyl disulfide.

Examples of the thiuram-based accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like, with tetramethylthiuram monosulfide being preferred.

The amount of the thiazole-based accelerator used is preferably 0.1 to 10 parts by mass based on 100 parts by mass of the base rubber.

The thiuram based accelerator is preferably used in an amount of 0.1 to 10 parts by mass based on 100 parts by mass of the base rubber.

(Crosslinking facilitation aid)

The rubber composition may contain a crosslinking promoting adjuvant. Examples of the crosslinking accelerator include zinc oxide and stearic acid. The amount of the crosslinking acceleration assistant used is preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the base rubber.

(Other Components)

The rubber composition may contain a filler, a processing aid, an antioxidant, a peptizer, a pigment, and the like as compounding agents that are generally used as rubber compounding agents, within a range that does not impair the gist of the present invention.

As the filler, a filler commonly used as a rubber compounding agent can be used, and examples thereof include carbon black, silica, calcium carbonate, talc, clay, magnesium carbonate, alumina, and the like, and carbon black and calcium carbonate are preferable.

The content of the filler is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, particularly preferably 20 parts by mass or more, preferably 100 parts by mass or less, further preferably 70 parts by mass or less, further preferably 50 parts by mass or less, based on 100 parts by mass of the base rubber.

Examples of the processing aid include fatty acids (stearic acid and the like) having 12 to 30 carbon atoms, fatty acid esters, fatty acid metal salts, fatty acid amides, hydrocarbons (paraffins), process oils, and the like.

As the anti-aging agent, there is used, can be exemplified by diethyl ether nickel thiocarbamate nickel dibutyldithiocarbamate, and the like.

The rubber composition preferably contains no oil component such as extender oil and process oil. The content of the oil component in the rubber composition is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 1 part by mass or less, per 100 parts by mass of the base rubber.

The hardness (durometer, type a hardness) of the cured product of the rubber composition is preferably 10 or more, more preferably 15 or more, further preferably 20 or more, preferably 90 or less, more preferably 85 or less, further preferably 80 or less. When the hardness of the cured product is 10 or more, the sheet is suitably transported, the transport force is further improved, and when the hardness of the cured product is 90 or less, the roll shaft is more easily pushed in.

< Production of rubber composition for sheet conveying roller >

The rubber composition for a sheet conveying roller can be prepared by compounding a base rubber and, if necessary, other raw materials, and kneading the resultant with a kneader, a Banbury mixer, an open roll or the like. The method and conditions of kneading are appropriately selected according to the production scale.

In the method for producing the rubber composition for a sheet conveying roller, it is preferable to mix a base rubber and the petroleum resin at a temperature equal to or higher than the softening point of the petroleum resin, wherein the base rubber contains 50 mass% or more of a diene rubber. That is, the rubber composition for a sheet conveying roller is preferably obtained by kneading a base rubber containing 50 mass% or more of a diene rubber and a petroleum resin at a temperature equal to or higher than the softening point of the petroleum resin.

The mixing temperature (material temperature) at the time of mixing the base rubber and the petroleum resin is preferably not less than the softening point of the petroleum resin. By mixing at a temperature higher than the softening point of the petroleum resin, it is possible to uniformly mix in the rubber. When a plurality of petroleum resins are contained, the petroleum resins are mixed at a temperature equal to or higher than the softening point of the petroleum resin having the highest softening point. When the softening point of the petroleum resin is set to T ℃, the mixing temperature is more preferably t+3 ℃ or higher, and still more preferably t+5 ℃ or higher. When a plurality of petroleum resins are contained, the softening point of the petroleum resin having the highest softening point is set to T ℃. The upper limit of the mixing temperature is not particularly limited, but is usually less than 200 ℃.

When the rubber composition contains a crosslinking agent, the method for producing a rubber composition preferably comprises the steps of: step 1: mixing a base rubber containing 50 mass% or more of a diene rubber with a petroleum resin at a temperature equal to or higher than the softening point of the petroleum resin to obtain a mixed material; and (2) a step of: a crosslinking agent is mixed in the kneaded mixture. By having the 1 st step and the 2 nd step, the petroleum resin can be uniformly dispersed in the rubber component, and scorch due to the crosslinking agent can be suppressed.

In the step 1, a base rubber and a petroleum resin are mixed to prepare a mixture. The mixing temperature (material temperature) at the time of mixing the base rubber and the petroleum resin is preferably not less than the softening point of the petroleum resin. By mixing at a temperature higher than the softening point of the petroleum resin, it is possible to uniformly mix in the rubber. When a plurality of petroleum resins are contained, the petroleum resins are mixed at a temperature equal to or higher than the softening point of the petroleum resin having the highest softening point. When the softening point of the petroleum resin is set to T ℃, the mixing temperature in the step 1 is more preferably T+3 ℃ or higher, and still more preferably T+5 ℃ or higher. The upper limit of the mixing temperature in the step 1 is not particularly limited, but is usually less than 200 ℃. When a plurality of petroleum resins are contained, the softening point of the petroleum resin having the highest softening point is set to T ℃.

The mixing in the step 1 may be performed by a kneader, a Banbury mixer, an open mill or the like, but is preferably performed by a kneader.

In the step 1, only the base rubber and the petroleum resin may be mixed, or other components (crosslinking accelerator, filler, processing aid, and antioxidant) than the crosslinking agent may be mixed. In the step 1, it is preferable that the crosslinking agent and the crosslinking accelerator are not mixed.

In the step 2, the kneaded material and a crosslinking agent are mixed to prepare a rubber composition. The mixing temperature (material temperature) at the time of mixing the kneaded material and the crosslinking agent is preferably 30 ℃ or higher, more preferably 40 ℃ or higher, still more preferably 50 ℃ or higher, preferably 150 ℃ or lower, more preferably 120 ℃ or lower, still more preferably 100 ℃ or lower. If the mixing temperature is 30 ℃ or higher, the crosslinking agent is easily mixed by plasticizing the rubber, and if the mixing temperature is 150 ℃ or lower, scorch can be suppressed.

The mixing in the step 2 may be performed by a kneader, a Banbury mixer, an open mill or the like, and is preferably performed by an open mill.

When the rubber composition contains a vulcanization accelerator, the crosslinking accelerator is preferably added in step 2. When the rubber composition contains a filler, a processing aid, or an anti-aging agent, these components are preferably added in step 1.

< Sheet conveying roller >

The sheet conveying roller of the present invention is obtained by molding the rubber composition for a sheet conveying roller.

The shape of the sheet conveying roller may be a cylinder, a polygonal cylinder, or a polygonal cylinder. When the sheet conveying roller has a cylindrical shape or a polygonal cylindrical shape, the sheet conveying roller preferably has a shaft. The material of the shaft is not particularly limited, and examples thereof include metal, ceramic, resin, and the like.

Fig. 1 shows an example of a sheet conveying roller. The sheet conveying roller 1 shown in fig. 1 includes: the roll body 2 is obtained by forming the rubber composition for a sheet conveying roll of the present invention described above into a tubular shape. A through hole 3 having a circular cross section is provided in the center of the roller body 2, and a cylindrical shaft 4 connected to a drive system, not shown, or the like is inserted and fixed in the through hole 3. The outer peripheral surface of the roller body 2 is formed in a cylindrical shape concentric with the through hole 3 and the shaft 4.

The roller body 2 and the shaft 4 are fixed to each other, for example, by pressing the shaft 4 having an outer diameter larger than an inner diameter of the through hole 3 into the through hole 3 of the roller body 2 or the like so that no idling occurs. That is, by the interference based on the diameter difference between the two, a certain idling torque (limit torque that does not generate idling) is ensured between the two.

The shaft 4 is formed of, for example, metal, ceramic, hard resin, or the like. The plurality of roller bodies 2 may be fixed to a plurality of portions of the 1 shaft 4 as needed.

The method of manufacturing the roller body 2 may be exemplified by: a method in which the rubber composition is molded into a tubular shape by an extrusion molding method or the like, and then crosslinked by a compression crosslinking method or the like; and a method of forming a tube shape by a transfer molding method (transfer molding method) or the like and crosslinking.

The roller body 2 may be polished to have a predetermined surface roughness on the outer peripheral surface at any time point in the manufacturing process, or may be subjected to knurling, texturing, or the like, as necessary. The both ends of the roller body 2 may be cut so that the outer peripheral surface has a predetermined width. The outer peripheral surface of the roller body 2 may be coated with an arbitrary coating layer.

In addition, the roller body 2 may be formed in a double-layer structure of an outer layer on the outer peripheral surface 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 the rubber composition of the present invention described above. Among them, in view of simplifying the structure, improving productivity, reducing manufacturing costs, and the like, it is preferable that the roller body 2 is formed in a single-layer structure as shown in fig. 1.

In addition, the roller body 2 may be formed in a porous structure. However, in order to improve the abrasion resistance or reduce the compression set (compression set) so that dishing due to deformation is not easily generated even when the state of contact at 1 continues for a relatively long period of time, it is preferable that the roller body 2 be of a substantially non-porous structure.

The through hole 3 may be provided at a position eccentric from the center of the roller body 2 according to the use of the sheet conveying roller 1. In addition, the outer peripheral surface of the roller main body 2 may be a deformed shape, for example, a part of a cylindrical outer peripheral surface is cut into a planar shape or the like, instead of a cylindrical shape. To manufacture the sheet conveying roller 1 having the roller body 2 of such a deformed shape, the roller body 2 of a deformed shape may be directly formed by the above-described manufacturing method and then crosslinked, or the roller body 2 formed into a cylindrical shape may be formed into a deformed shape by post-processing.

The shaft 4 formed in a deformed shape corresponding to the deformed shape of the roller body 2 may be pressed into the through hole 3 of the roller body 2 formed in a cylindrical shape, thereby deforming the roller body 2 into the deformed shape.

In this case, the cylindrical outer peripheral surface 5 before deformation can be subjected to polishing, knurling, texturing, and the like of the outer peripheral surface 5, and thus the workability can be improved.

< Image Forming apparatus >

The sheet conveying roller of the present invention can be incorporated into various image forming apparatuses such as a laser printer, an electrostatic copier, a plain paper facsimile machine, or an electrophotographic method using a complex apparatus of these, document processing apparatuses that scan or sort bills, and the like. The sheet conveying roller of the present invention may be incorporated in, for example, an inkjet printer, an ATM, or the like. In particular, the sheet conveying roller of the present invention is suitable for a roller for document processing apparatuses requiring high conveying ability because it has an excellent friction coefficient due to the inclusion of petroleum resin.

The sheet conveying roller of the present invention rotates while being in contact with a sheet, and conveys the sheet by friction. Examples of the sheet include a single sheet such as a single sheet and a continuous sheet such as a continuous sheet. The sheet conveying roller may be used as, for example, a paper feed roller, a conveying roller, a platen roller, a paper discharge roller (PAPER DISCHARGE roller), or the like.

Examples (example)

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples, and modifications and embodiments within the scope of the present invention are included in the scope of the present invention.

[ Evaluation method ]

(1) Hardness of

The hardness of the cured product of the rubber composition was measured according to JIS K6253-3 (2012) using a durometer (manufactured by Polymer Co., ltd.). Specifically, a sheet having a thickness of 2mm was produced by pressurizing the rubber composition at 170℃for 20 minutes. In a state where 3 sheets are overlapped so as not to be affected by a measurement substrate or the like, the sheets are brought into contact with a pressing plate of a type a durometer, and the numerical value is read 3 seconds after the contact.

(2) Tensile Strength, elongation at Break

The tensile strength and elongation at break (elongation at break) of the cured product of the rubber composition were measured in accordance with JIS K6251 (2017). Specifically, a sheet having a thickness of 2mm was produced by pressing the sheet at 170℃for 20 minutes using the rubber composition, and the sheet was punched into a dumbbell shape (dumbbell No. 3 shape, thickness of parallel portion 2mm, initial distance between graticules 20 mm) to produce a test piece. Physical properties (measurement temperature 23 ℃ C., stretching speed 500 mm/min) were measured using a tensile test measurement apparatus. Then, the tensile strength was calculated by dividing the maximum tensile force recorded until the test piece was cut by the cross-sectional area of the test piece before the test.

(3) Determination of the coefficient of Friction

As shown in fig. 2, plain paper 11 (manufactured by fuji film commercial innovation (FUJIFILM Business Innovation) company, P paper (width 60mm, length 210 mm)) was placed on a plate 10 made of Polytetrafluoroethylene (PTFE) horizontally disposed. The roller body 2 of the sheet conveying roller 1 is placed on the paper 11, and a vertical load W ₁ (=300 gf) is applied to the shaft 4, so that the roller body 2 is pressure-bonded to the plate 10.

Next, the roller body 2 was rotated at 200rpm in the direction indicated by the arrow R1 of the one-dot chain line at a temperature of 23 ℃ and a relative humidity of 55%, and at this time, the conveying force F (gf) applied to the load sensor 12 connected to one end of the paper 11 was measured.

From the measured conveying force F and vertical load W ₁ (=300 gf), the initial friction coefficient μ is determined by formula (1).

μ＝F(gf)/W₁(gf) (1)

(4) Forced abrasion test

As shown in fig. 2, plain paper 11 (P paper manufactured by fuji film commercial innovation company) is placed on a plate 10 made of Polytetrafluoroethylene (PTFE) disposed horizontally. On this paper 11, the roller body 2 of the sheet conveying roller 1 is placed, and a vertical load W ₁ (=500 gf) is applied to the shaft 4, so that the roller body 2 is pressed against the plate 10.

Next, the roller body 2 was continuously rotated at 200rpm for 10 minutes in the direction indicated by the arrow R1 of the one-dot chain line at a temperature of 23 ℃ and a relative humidity of 55%. Then, the wear loss (%) was obtained from the mass W ₀ (g) of the roller body 2 before rotation and the mass W ₁ (g) of the roller body 2 after rotation by the following formula (2).

Wear loss (%) =100× (W ₀-W₁)/W₀ (formula 2)

[ Preparation of rubber composition ]

The raw materials were mixed to prepare a rubber composition so as to have the formulations shown in tables 1 to 3. Specifically, first, a base rubber, a petroleum resin, and a filler are mixed using a kneader to prepare a mixture. At this time, after the temperature (material temperature) in the kneader tank reached a predetermined temperature, the mixture was mixed for 1 minute. Subsequently, the obtained mixture is cooled, and the mixture is mixed with a crosslinking agent, a crosslinking accelerator and a crosslinking accelerator auxiliary agent as needed, using an open mill having a surface temperature controlled to 30 to 50 ℃, to prepare a rubber composition. The measurement results of the cured products of the obtained rubber compositions are shown in tables 1 to 3.

TABLE 1

TABLE 2

TABLE 3

The raw materials used in tables 1 to 3 are as follows.

IR: nipol (registered trademark) IR2200 (isoprene rubber) manufactured by Japanese Rui Weng Zhushi Co., ltd

NR: vietnam manufacturing, natural rubber (CV-60)

SBR: japanese patent No. Weng Zhushi, inc. "Nipol (registered trademark) 1502" (non-oil-filled styrene-butadiene rubber, combined styrene content: 23.5% by mass, mooney viscosity ML ₁₊₄ (100 ℃ C.): 52.0)

EPDM: "Esprene (registered trademark) 505A" (non-oil-filled EPDM) (ethylene-propylene-ethylidene norbornene copolymer, ethylene content: 50% by mass, diene component content: 9.5% by mass) manufactured by Sumitomo chemical Co., ltd

Petroleum resin 1: "T-REZ (registered trademark) HA085" (hydrogenated dicyclopentadiene Petroleum resin, softening Point: 88.0 ℃ C.)

Petroleum resin 2: "T-REZ PR801" (hydrogenated aromatic-dicyclopentadiene copolymer-based petroleum resin, softening point: 90.0 ℃ C.)

Petroleum resin 3: "T-REZ RB093" (aliphatic petroleum resin, softening point: 93.0 ℃ C.)

Petroleum resin 4: "T-REZ RD104" (aliphatic-aromatic copolymer-based petroleum resin, softening point: 103.0 ℃ C.)

Petroleum resin 5: "Petrotack (registered trademark) 100V" (aliphatic-aromatic copolymer-based petroleum resin, softening point: 96 ℃ C.)

Petroleum resin 6: "Petcol (registered trademark) LX" (aromatic petroleum resin, softening point: 98 ℃ C.)

Petroleum resin 7: "ARKON (registered trademark) M-100" (partially hydrogenated aromatic petroleum resin, softening point: 100 ℃ C.)

Petroleum resin 8: ARKON P-100 (fully hydrogenated aromatic petroleum resin, softening point: 100 ℃ C.)

Petroleum resin 9: "YS Resin SX100" (styrene Resin, softening point: 100 ℃ C.) (manufactured by Anyuan chemical Co., ltd.)

Carbon black: manufactured by Tokai Carbon Co., ltd., SEAST (registered trademark) 3

Calcium carbonate: Prepare manufactured by North America Industrial Co., ltd. (Bihoku Funka Kogyo Co., ltd.), BF-300

Zinc oxide: zinc oxide No. 2 manufactured by Mitsui metal mining Co., ltd

Stearic acid: manufactured by Nikko corporation, stearic acid "Ailanthus (Tsuaki)";

sulfur: sulfur containing 5% oil, manufactured by Crane Chemie Co., ltd

Crosslinking accelerator 1: "Nocceler (registered trademark) TOT-N" (tetra (2-ethylhexyl) thiuram disulfide manufactured by Dain Ind Chemie Co., ltd.)

Crosslinking accelerator 2: "Nocceler DM" (2, 2' -dibenzothiazyl disulfide) manufactured by Dain chemical industries, inc

Organic peroxide: "PERCUMYL (registered trademark) D" (dicumyl peroxide) manufactured by Nikko Co., ltd

[ Production of sheet conveying roller ]

The rubber composition obtained above was molded into a cylindrical shape by transfer molding under molding conditions of 170℃for 30 minutes. The shaft (outer diameter: 12 mm) was pressed into a cylindrical molded body, and the cylindrical molded body was ground by a cylindrical grinder so that the outer diameter of the rubber roller became 22mm, and the width of the rubber roller portion was cut into 25mm, whereby a sheet conveying roller was produced. The evaluation results of the obtained sheet conveying roller are shown in tables 1 to 3.

Rubber compositions No.1 to 9 contain isoprene rubber (diene rubber) as a base rubber, petroleum resin and sulfur as a crosslinking agent. Rubber composition No.10 contains isoprene rubber (diene rubber) and sulfur, but does not contain petroleum resin. The friction coefficient of the sheet conveying roller formed of the rubber compositions No.1 to 9 was improved as compared with the sheet conveying roller formed of the rubber composition No.10 containing no petroleum resin.

Rubber compositions No.11 to 19 contain isoprene rubber (diene rubber) as a base rubber, petroleum resin and an organic peroxide as a crosslinking agent. The rubber composition No.20 contains isoprene rubber (diene rubber) and an organic peroxide, but does not contain petroleum resin. The friction coefficient of the sheet conveying roller formed of the rubber compositions No.11 to 19 is improved as compared with the sheet conveying roller formed of the rubber composition No.20 containing no petroleum resin.

Rubber compositions Nos. 21 to 23 are cases where the base rubber contains a natural rubber (diene rubber), a petroleum resin and sulfur as a crosslinking agent. The rubber composition No.24 contains a natural rubber (diene rubber) and sulfur as a crosslinking agent, but does not contain a petroleum resin. The friction coefficient of the sheet conveying roller formed of the rubber compositions No.21 to 23 is improved as compared with the sheet conveying roller formed of the rubber composition No.24 containing no petroleum resin.

The rubber compositions No.25 to 28 contain isoprene rubber (diene rubber) as a base rubber, EPDM, petroleum resin, and an organic peroxide as a crosslinking agent, and the content of the diene rubber in the base rubber is 50 mass% or more. The rubber composition No.29 contains isoprene rubber (diene rubber) as a base rubber, EPDM, and an organic peroxide as a crosslinking agent, but does not contain petroleum resin. The friction coefficient of the sheet conveying roller formed of the rubber compositions No.25 to 28 is improved as compared with the sheet conveying roller formed of the rubber composition No.29 containing no petroleum resin.

Rubber compositions No.30 and 31 contain isoprene rubber (diene rubber) and styrene-butadiene rubber (diene rubber) as base rubbers, and EPDM, petroleum resin, and organic peroxide as a crosslinking agent, and the content of diene rubber in the base rubbers is 50 mass% or more. The rubber composition No.32 contains isoprene rubber (diene rubber), styrene-butadiene rubber (diene rubber), EPDM, and an organic peroxide, but does not contain a petroleum resin. The friction coefficient of the sheet conveying roller formed of the rubber compositions No.30 and 31 was improved as compared with the sheet conveying roller formed of the rubber composition No.32 containing no petroleum resin.

The invention (1) is a rubber composition for a sheet conveying roller, characterized in that,

The rubber composition for a sheet conveying roller contains a base rubber and a petroleum resin,

The base rubber contains a diene rubber,

The content of the diene rubber in 100 mass% of the base rubber is 50 mass% or more.

The present invention (2) is the rubber composition for a sheet conveying roller according to the present invention (1), wherein the petroleum resin is 1 or more petroleum resins selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, dicyclopentadiene petroleum resins, aliphatic-dicyclopentadiene copolymer petroleum resins, aromatic-dicyclopentadiene copolymer petroleum resins, aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, hydrogenated aliphatic-aromatic copolymer petroleum resins, hydrogenated dicyclopentadiene petroleum resins, hydrogenated aliphatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, and styrene petroleum resins.

The invention (3) is the rubber composition for a sheet conveying roller according to the invention (1) or (2), wherein the diene rubber contains isoprene rubber and/or natural rubber.

The invention (4) is the rubber composition for a sheet conveying roller according to any one of the inventions (1) to (3), wherein the petroleum resin is contained in an amount of 1 to 15 parts by mass based on 100 parts by mass of the base rubber.

The invention (5) is the rubber composition for a sheet conveying roller according to any one of the inventions (1) to (4), wherein the base rubber further contains an ethylene- α -olefin copolymer and/or an ethylene-vinyl acetate copolymer.

The invention (6) is the rubber composition for a sheet conveying roller according to any one of the inventions (1) to (5), wherein the sheet is a single sheet.

The present invention (7) is a sheet conveying roller obtained by molding the rubber composition for a sheet conveying roller according to any one of the present invention (1) to (6).

The present invention (8) is a method for producing a rubber composition for a sheet conveying roller, comprising a base rubber and a petroleum resin, wherein the base rubber containing 50 mass% or more of a diene rubber and the petroleum resin are kneaded at a temperature equal to or higher than the softening point of the petroleum resin.

The present invention (9) is a method for producing a rubber composition for a sheet conveying roller, comprising a base rubber, a petroleum resin and a crosslinking agent, characterized by comprising the steps of:

Step 1: mixing a base rubber containing 50 mass% or more of a diene rubber with the petroleum resin at a temperature equal to or higher than the softening point of the petroleum resin to obtain a mixed product; and

2, The step: a crosslinking agent is mixed in the kneaded mixture.

Claims

1. A rubber composition for a sheet conveying roller, characterized by comprising a base rubber and a petroleum resin,

The base rubber contains a diene rubber,

2. The rubber composition for a sheet conveying roller according to claim 1, wherein the petroleum resin is one or more petroleum resins selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, dicyclopentadiene petroleum resins, aliphatic-dicyclopentadiene copolymer petroleum resins, aromatic-dicyclopentadiene copolymer petroleum resins, aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, hydrogenated aliphatic-aromatic copolymer petroleum resins, hydrogenated dicyclopentadiene petroleum resins, hydrogenated aliphatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aromatic-dicyclopentadiene copolymer petroleum resins, hydrogenated aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins, and styrene petroleum resins.

3. The rubber composition for a sheet conveying roller according to claim 1 or 2, wherein the diene rubber contains isoprene rubber and/or natural rubber.

4. The rubber composition for a sheet conveying roller according to claim 1 or 2, wherein the petroleum resin is contained in an amount of 1 to 15 parts by mass based on 100 parts by mass of the base rubber.

5. The rubber composition for a sheet conveying roller according to claim 1 or 2, wherein the base rubber further contains an ethylene- α -olefin copolymer and/or an ethylene-vinyl acetate copolymer.

6. The rubber composition for a sheet conveying roller according to claim 1 or 2, wherein the sheet is a single sheet.

7. A sheet conveying roller obtained by molding the rubber composition for a sheet conveying roller according to claim 1 or 2.

8. A process for producing a rubber composition for a sheet conveying roller, which comprises a base rubber and a petroleum resin, characterized in that the base rubber containing 50 mass% or more of a diene rubber and the petroleum resin are kneaded at a temperature equal to or higher than the softening point of the petroleum resin.

9. A method for producing a rubber composition for a sheet conveying roller, which comprises a base rubber, a petroleum resin and a crosslinking agent, characterized in that the method for producing a rubber composition for a sheet conveying roller comprises the following steps:

2, The step: a crosslinking agent is mixed in the kneaded mixture.