Rubber composition and rubber roller

Abstract

To provide a technique capable of improving the compression set of a rubber member.SOLUTION: A rubber composition comprises: a rubber component; carbon black; a compound represented by Formula (1); and an aminoalkylthiosulfate compound. (In Formula (1), R1, R2, R3, and R4 each independently represent a monovalent organic group having 5 or more carbon atoms. n is an integer from 1 to 20).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a rubber composition and a rubber roller. [Background technology]

[0002] Patent Document 1 describes an elastic member containing vulcanized rubber vulcanized in the presence of a specific sulfur atom-containing compound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-240402 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technique of Patent Document 1 was insufficient in improving compression set. The present disclosure has been made in view of the above circumstances, and has an object to provide a technique capable of improving the compression set of a rubber member. The present disclosure can be realized in the following aspects. [Means for solving the problem]

[0005] A rubber composition comprising a rubber component, carbon black, a compound represented by the following formula (1), and a compound represented by the following formula (2). [ka] (In formula (1), R 1 , R 2 , R 3 , R 4 each independently represents a monovalent organic group having 5 or more carbon atoms, and n is an integer of 1 to 20. [ka] (In formula (2), R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, Or, R 1 and R 2 is R 1 and R 2 represents an alkanediyl group having 2 to 12 carbon atoms, which may have one or more substituents and to which m represents an integer from 2 to 9; n represents 1 or 2; M n+ is H + or a metal ion having a valence of n. Effect of the Invention

[0006] According to the present disclosure, the compression set of the rubber member can be improved. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram illustrating a rubber roller according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining a method for measuring compression set. [Diagram 3] FIG. 2 is a diagram for explaining a method for measuring compression set. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Here, a preferred example of the present disclosure is given. [1] A rubber composition comprising a rubber component, carbon black, a compound represented by the following formula (1), and a compound represented by the following formula (2): [ka] (In formula (1), R 1 , R 2 , R 3 , R 4each independently represents a monovalent organic group having 5 or more carbon atoms, and n is an integer of 1 to 20. [ka] (In formula (2), R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, Or, R 1 and R 2 is R 1 and R 2 represents an alkanediyl group having 2 to 12 carbon atoms, which may have one or more substituents and to which m represents an integer from 2 to 9; n represents 1 or 2; M n+ is H + or a metal ion having a valence of n. [2] The rubber composition according to [1], wherein the rubber component includes at least one selected from the group consisting of NBR (nitrile butadiene rubber), ECO (epichlorohydrin rubber), and EPDM (ethylene propylene diene rubber). [3] A rubber roller using the rubber composition according to [1] or [2].

[0009] The present disclosure will be described in detail below. In this specification, when a numerical range is described using "-", the lower limit and the upper limit are included unless otherwise specified. For example, the description "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". In this specification, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0010] 1. Rubber composition The rubber composition contains a rubber component, carbon black, the compound represented by the above formula (1), and the compound represented by the above formula (2).

[0011] 1.1 Rubber components The rubber component is not particularly limited. The rubber component preferably contains at least one selected from the group consisting of NBR (nitrile butadiene rubber), ECO (epichlorohydrin rubber), and EPDM (ethylene propylene diene rubber). In this embodiment, the total amount of NBR, ECO, and EPDM is the total amount of rubber.

[0012] Since NBR itself is a polar rubber, it acts to finely adjust the roller resistance value of the rubber roller 10. The NBR is preferably one or more types selected from low nitrile NBR, medium nitrile NBR, medium-high nitrile NBR, high nitrile NBR, and very high nitrile NBR, which are classified according to the acrylonitrile content. Only one type of NBR may be used, or two or more types may be used.

[0013] From the viewpoint of ensuring processability, the compounding ratio of NBR is preferably 25 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more, when the total amount of rubber is 100 parts by mass. From the viewpoint of suppressing the occurrence of ozone cracks, the compounding ratio of the above NBR is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less. From these viewpoints, the compounding ratio of the above NBR is preferably 25 parts by mass or more and 70 parts by mass or less, more preferably 35 parts by mass or more and 60 parts by mass or less, and even more preferably 40 parts by mass or more and 55 parts by mass or less.

[0014] ECO is an ionically conductive rubber and has ozone resistance. ECO is preferably at least one selected from epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-propylene oxide binary copolymer, epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (GECO), and ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer. ECO may be of only one type or of two or more types.

[0015] The ethylene oxide unit content in GECO is preferably 20 mol % or more, more preferably 30 mol % or more, from the viewpoint of reducing the resistance value of the rubber member, and is preferably 80 mol % or less, more preferably 75 mol % or less, from the viewpoint of suppressing crystallization of ethylene oxide.

[0016] From the viewpoint of increasing the crosslink density, the allyl glycidyl ether unit content in GECO is preferably 2.0 mol % or more, and more preferably 6.0 mol % or more.

[0017] From the viewpoint of suppressing changes in electrical properties, the blending ratio of ECO is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, when the total amount of rubber is 100 parts by mass. From the viewpoint of ensuring moldability, the blending ratio of ECO is preferably 75 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less. From these viewpoints, the blending ratio of NBR is preferably 30 parts by mass or more and 75 parts by mass or less, more preferably 40 parts by mass or more and 65 parts by mass or less, and even more preferably 45 parts by mass or more and 60 parts by mass or less.

[0018] EPDM is a copolymer of ethylene, propylene, and dienes. EPDM is made possible to vulcanize with a vulcanizing agent by further copolymerizing dienes with an ethylene-propylene copolymer to introduce unsaturated bonds. The dienes are not particularly limited, but non-conjugated dienes are preferred. Examples of dienes that can be used include 5-ethylidene-2-norbornene, 1,4-hexadiene, and dicyclopentadiene. As the diene, 5-ethylidene-2-norbornene is preferred.

[0019] The content of dienes in EPDM (diene content) is not particularly limited. In terms of proceeding with a sufficient crosslinking (vulcanization) reaction and obtaining good mechanical properties, the content of dienes is preferably 2% by mass or more and 17% by mass or less, more preferably 2.5% by mass or more and 16% by mass or less, and even more preferably 3% by mass or more and 15% by mass or less, when the total mass of ethylene, propylene, and dienes is 100% by mass.

[0020] The ethylene content in the EPDM is not particularly limited. From the viewpoint of heat resistance and permanent deformation resistance, the ethylene content is preferably 40% by mass or more and 80% by mass or less, more preferably 42% by mass or more and 70% by mass or less, and even more preferably 45% by mass or more and 60% by mass or less, when the total mass of ethylene, propylene, and dienes is 100% by mass. The EPDM may be one type or two or more types.

[0021] From the viewpoint of ensuring the blending ratio of NBR or ECO, the blending ratio of EPDM is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, when the total amount of rubber is 100 parts by mass. The lower limit of the blending ratio of the EPDM is not particularly limited, and may be 0 parts by mass, 5 parts by mass or more, or 10 parts by mass or more.

[0022] 1.2 Carbon black The carbon black is not particularly limited. Carbon black has the effect of improving the mechanical properties of the rubber member. Carbon black can also suppress the increase in resistance value during continuous current flow in a conductive rubber member. The carbon black may be carbon black manufactured by a known manufacturing method such as an oil furnace method, a gas furnace method, or an acetylene method. Specifically, the carbon black may be furnace black, channel black, acetylene black, or the like. Carbon black may be used as a powder or may be granulated by a dry granulation method or a wet granulation method. The carbon black may be a commercially available product. The commercially available product is preferably at least one selected from HAF (High Abrasion Furnace), SAF (Super Abrasion Furnace), ISAF (Intermediate SAF), FEF (Fast Extrusion Furnace), MAF, GPF (General Purpose Furnace), and SRF (Semi-Reinforcing Furnace). Only one type of carbon black may be used, or two or more types may be used.

[0023] From the viewpoint of mechanical properties and / or electrical properties, the blending ratio of carbon black is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the total amount of rubber. From the viewpoint of ensuring moldability of the rubber composition, the blending ratio of the carbon black is preferably 60 parts by mass or less, preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. From these viewpoints, the blending ratio of the carbon black is preferably 5 parts by mass or more and 60 parts by mass or less, more preferably 10 parts by mass or more and 40 parts by mass or less, and even more preferably 15 parts by mass or more and 30 parts by mass or less.

[0024] 1.3 Compound represented by formula (1) The rubber composition contains at least a compound represented by the following formula (1). [ka] (In formula (1), R 1 , R 2 , R 3 , R 4 each independently represents a monovalent organic group having 5 or more carbon atoms, and n is an integer of 1 to 20.

[0025] R in the above formula (1) 1 , R 2 , R 3 , R 4are each independently a monovalent organic group having 5 or more carbon atoms, preferably a monovalent organic group having 5 or more and 10 or less carbon atoms. n in the above formula (1) is an integer of 1 to 20, preferably an integer of 2 to 10, more preferably an integer of 4 to 8. R 1 , R 2 , R 3 , R 4 If the carbon number of n is 5 or more, the scorch time can be sufficiently secured, and extrusion at high temperatures can be easily realized. Also, if n is within the above range, the vulcanization speed can be kept at a moderate level, and productivity can be easily improved.

[0026] R in the above formula (1) 1 , R 2 , R 3 , R 4 is preferably selected from an aryl group, a linear or branched alkyl group. Examples of the aryl group include a phenyl group and a biphenyl group. Examples of the alkyl group include a pentyl group, a hexyl group, a heptyl group, an octyl group, and a cyclohexyl group. At least one hydrogen atom of the alkyl group may be substituted with a halogen atom or an aryl group. For example, R in the above formula (1) 1 , R 2 , R 3 , R 4 R in the above formula (1) may be an aralkyl group such as a benzyl group or a phenethyl group. 1 , R 2 , R 3 , R 4 When is a benzyl group, a rubber member having excellent crosslinking efficiency and small compression set can be obtained. In other words, among the compounds represented by the above formula (1), the compound represented by the following formula (1.1) is particularly preferred.

[0027] [ka] (In formula (1.1), R 11 ~R 15 , R 21 ~R 25 , R 31 ~R 35 , R 41 ~R45 each independently represents a hydrogen atom or a monovalent substituent, and n is an integer of 1 to 20.

[0028] R in the above formula (1.1) 11 ~R 15 , R 21 ~R 25 , R 31 ~R 35 , R 41 ~R 45 The monovalent substituent is preferably selected from a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an amino group, a nitrile group, a carboxyl group, a hydroxyl group, an isocyanate group, an acryloyl group, and a halogen atom. The alkyl group is, for example, a methyl group, an ethyl group, a propyl group, and the like. The alkenyl group is, for example, a methylene group, an ethylene group, and the like.

[0029] In the above formula (1.1), n ​​is 6, and R 11 ~R 15 , R 21 ~R 25 , R 31 ~R 35 , R 41 ~R 45 A compound in which all are hydrogen atoms is called 1,6-bis(N,N'-benzylthiocarbamoyldithio)hexane. 1,6-bis(N,N'-benzylthiocarbamoyldithio)hexane has a good balance between scorch time and vulcanization speed, and is particularly suitable.

[0030] From the viewpoint of ensuring various physical properties, the compounding ratio of the compound represented by formula (1) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the total amount of rubber. From the viewpoint of scorch time and vulcanization speed, the compounding ratio of the compound represented by formula (1) is preferably 5 parts by mass or less, preferably 3 parts by mass or less, and even more preferably 1.5 parts by mass or less. From these viewpoints, the compounding ratio of the compound represented by formula (1) is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.3 parts by mass or more and 3 parts by mass or less, and even more preferably 0.5 parts by mass or more and 1.5 parts by mass or less.

[0031] 1.4 Compound represented by formula (2) The rubber composition contains at least a compound represented by the following formula (2). [ka] (In formula (2), R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, Or, R 1 and R 2 is R 1 and R 2 represents an alkanediyl group having 2 to 12 carbon atoms, which may have one or more substituents and to which m represents an integer from 2 to 9; n represents 1 or 2; M n+ is H + or a metal ion having a valence of n.

[0032] Next, preferred groups in the formula (2) will be described. R 1 and R 2 are each preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, and more preferably a hydrogen atom. m is preferably an integer from 2 to 8, more preferably an integer from 2 to 7, and even more preferably an integer from 2 to 5. n is preferably 1.

[0033] The n-valent metal ion is preferably selected from an alkali metal ion, an alkaline earth metal ion, a manganese ion, an iron ion, a copper ion, and a zinc ion. The alkali metal ion is, for example, a lithium ion, a sodium ion, a potassium ion, and a cesium ion. The alkaline earth metal ion is, for example, a magnesium ion, a calcium ion, a strontium ion, and a barium ion. M n+ is preferably H + or an alkali metal ion, more preferably H + or sodium ion, more preferably H + It is.

[0034] R 1 , R 2 A preferred combination of and m is R 1 and R 2 are both hydrogen atoms and m is an integer of 2 to 8.

[0035] The compound represented by formula (2) is preferably at least one selected from, for example, S-(aminoalkyl)thiosulfuric acid, S-(aminoalkyl)thiosulfate salts, S-(N,N-dialkylaminoalkyl)thiosulfuric acid, S-(N,N-dialkylaminoalkyl)thiosulfate salts, S-(N-monoalkylaminoalkyl)thiosulfuric acid, and S-(N-monoalkylaminoalkyl)thiosulfate salts.

[0036] Examples of S-(aminoalkyl)thiosulfuric acid include S-(2-aminoethyl)thiosulfuric acid, S-(3-aminopropyl)thiosulfuric acid, S-(4-aminobutyl)thiosulfuric acid, S-(5-aminopentyl)thiosulfuric acid, S-(6-aminohexyl)thiosulfuric acid, S-(7-aminoheptyl)thiosulfuric acid, S-(8-aminooctyl)thiosulfuric acid, and S-(9-aminononyl)thiosulfuric acid. Examples of S-(aminoalkyl)thiosulfates include sodium S-(2-aminoethyl)thiosulfate, sodium S-(3-aminopropyl)thiosulfate, sodium S-(4-aminobutyl)thiosulfate, sodium S-(5-aminopentyl)thiosulfate, sodium S-(6-aminohexyl)thiosulfate, sodium S-(7-aminoheptyl)thiosulfate, sodium S-(8-aminooctyl)thiosulfate, sodium S-(9-aminononyl)thiosulfate, and the like. Examples of S-(N,N-dialkylaminoalkyl)thiosulfuric acid include S-(2-N,N-dimethylaminoethyl)thiosulfuric acid, S-(3-N,N-dimethylaminopropyl)thiosulfuric acid, S-(4-N,N-dimethylaminobutyl)thiosulfuric acid, S-(5-N,N-dimethylaminopentyl)thiosulfuric acid, S-(6-N,N-dimethylaminohexyl)thiosulfuric acid, S-(7-N,N-dimethylaminoheptyl)thiosulfuric acid, S-(8-N,N-dimethylaminooctyl)thiosulfuric acid, and S-(9-N,N-dimethylaminononyl)thiosulfuric acid. Examples of S-(N,N-dialkylaminoalkyl)thiosulfates include sodium S-(2-N,N-dimethylaminoethyl)thiosulfate, sodium S-(3-N,N-dimethylaminopropyl)thiosulfate, sodium S-(4-N,N-dimethylaminobutyl)thiosulfate, sodium S-(5-N,N-dimethylaminopentyl)thiosulfate, sodium S-(6-N,N-dimethylaminohexyl)thiosulfate, sodium S-(7-N,N-dimethylaminoheptyl)thiosulfate, sodium S-(8-N,N-dimethylaminooctyl)thiosulfate, and sodium S-(9-N,N-dimethylaminononyl)thiosulfate. Examples of S-(N-monoalkylaminoalkyl)thiosulfuric acid include S-(2-N-methylaminoethyl)thiosulfuric acid, S-(3-N-methylaminopropyl)thiosulfuric acid, S-(4-N-methylaminobutyl)thiosulfuric acid, S-(5-N-methylaminopentyl)thiosulfuric acid, S-(6-N-methylaminohexyl)thiosulfuric acid, S-(7-N-methylaminoheptyl)thiosulfuric acid, S-(8-N-methylaminooctyl)thiosulfuric acid, and S-(9-N-methylaminononyl)thiosulfuric acid. Examples of S-(N-monoalkylaminoalkyl)thiosulfates include sodium S-(2-N-methylaminoethyl)thiosulfate, sodium S-(3-N-methylaminopropyl)thiosulfate, sodium S-(4-N-methylaminobutyl)thiosulfate, sodium S-(5-N-methylaminopentyl)thiosulfate, sodium S-(6-N-methylaminohexyl)thiosulfate, sodium S-(7-N-methylaminoheptyl)thiosulfate, sodium S-(8-N-methylaminooctyl)thiosulfate, and sodium S-(9-N-methylaminononyl)thiosulfate.

[0037] The compound represented by formula (2) is preferably one or more selected from the group consisting of S-(aminoalkyl)thiosulfuric acid and S-(aminoalkyl)thiosulfate salts, more preferably S-(aminoalkyl)thiosulfuric acid, and even more preferably S-(3-aminopropyl)thiosulfuric acid. S-(3-aminopropyl)thiosulfuric acid is represented by the following formula (2.1). [ka]

[0038] The compounding ratio of the compound represented by formula (2) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, based on 100 parts by mass of the total rubber, from the viewpoint of suppressing compression set. The compounding ratio of the compound represented by the above formula (2) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, from the viewpoint of scorch time and vulcanization speed. From these viewpoints, the compounding ratio of the compound represented by the above formula (2) is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.3 parts by mass or more and 3 parts by mass or less, and even more preferably 0.5 parts by mass or more and 3 parts by mass or less.

[0039] 1.5 Other ingredients The rubber composition may further contain other components different from the above components, as necessary. The other components include, for example, a crosslinking agent, a vulcanization accelerator (excluding the compound represented by formula (1)), a vulcanization accelerator assistant, a processing assistant, a softener, a foaming agent, a foaming assistant, a flame retardant, a filler (excluding carbon black), an antioxidant, an ion conductive agent, etc. Each of the other components may be one type only, or two or more types may be used.

[0040] The crosslinking agent may be, for example, a vulcanizing agent such as sulfur or a sulfur compound, or an organic peroxide-based crosslinking agent. The crosslinking agent may be one type or two or more types. The compounding ratio of the crosslinking agent is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and even more preferably 2 parts by mass or more and 8 parts by mass or less, based on 100 parts by mass of the total amount of rubber.

[0041] The vulcanization accelerator other than the compound represented by formula (1) is preferably one or more selected from thiuram compounds and sulfenamide compounds. The thiuram compounds are, for example, tetraethylenethiuram disulfide, etc. The sulfenamide compounds are, for example, N-cyclohexyl-2-benzothiazole sulfene, etc. The vulcanization accelerator may be one kind or two or more kinds. The total compounding ratio of the vulcanization accelerator other than the compound represented by formula (1) is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, and even more preferably 1.5 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the total amount of rubber.

[0042] The vulcanization accelerator aid mainly accelerates the action of the vulcanizing agent. The vulcanization accelerator aid is preferably one or more selected from metal elements such as zinc, beryllium, magnesium, calcium, barium, germanium, titanium, tin, zirconium, antimony, vanadium, bismuth, molybdenum, tungsten, tellurium, selenium, iron, nickel, cobalt, and osmium, and oxides or hydroxides thereof. Among these, one or more selected from zinc oxide, antimony dioxide, antimony trioxide, and magnesium oxide are more preferable from the viewpoint of high vulcanization effect. Only one type of vulcanization accelerator aid may be used, or two or more types may be used. The compounding ratio of the vulcanization accelerator aid is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and even more preferably 2 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the total amount of rubber.

[0043] The processing aid is preferably one or more selected from stearic acid, stearic acid esters, and zinc stearate. The compounding ratio of the processing aid is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.8 to 3 parts by mass, based on 100 parts by mass of the total amount of rubber.

[0044] The foaming agent is used when the rubber member is obtained as a foam (rubber sponge). When the rubber member is obtained as a non-foam (solid), the foaming agent may not be used. The foaming agent is preferably a thermal decomposition type foaming agent. The foaming agent is preferably one or more selected from azodicarbonamide, azobisisobutyronitrile, azobisacetoxyphenylethane, N,N'-dinitrosopentamethylene, 4,4'-oxybis(benzenesulfonylhydrazide), sodium hydrogen carbonate, and hydrazodicarbonamide. The foaming agent may be one type or two or more types. The total compounding ratio of the foaming agent is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 3 parts by mass or more and 25 parts by mass or less, and even more preferably 5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the total amount of rubber.

[0045] The filler other than carbon black is preferably one or more selected from calcium carbonate, magnesium carbonate, silicic acid, clay, talc, mica powder, bentonite, silica, alumina, aluminum silicate, and aluminum powder. The calcium carbonate is, for example, heavy calcium carbonate. The filler may be one type or two or more types. The compounding ratio of the filler other than carbon black is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the total amount of rubber.

[0046] 2. Manufacturing method of rubber components The method for producing the rubber member is not particularly limited. The rubber member can be produced by vulcanizing the above-mentioned rubber composition. For example, the method for producing the rubber member includes kneading the unvulcanized rubber composition with a kneader, molding the rubber composition, and heating the molded rubber composition to vulcanize it.

[0047] 3. Physical properties of rubber materials The thickness of the rubber member is not particularly limited and can be appropriately set depending on the application. The thickness of the rubber member may be, for example, 0.5 mm or more and 15 mm or less, 1 mm or more and 10 mm or less, or 2 mm or more and 8 mm or less.

[0048] The compression set of the rubber member is not particularly limited. When measured by the following measurement method, the compression set of the rubber member is preferably 0.105 mm or less, more preferably 0.103 mm or less, and even more preferably 0.101 mm or less. The lower limit of the compression set of the rubber member is usually 0.000 mm or more. The measurement method will be described with reference to Figs. 2 and 3. <Measurement method> From the prepared rubber composition, a cylindrical vulcanized rubber member 12 having an outer diameter of 15 mm and an inner diameter of 4.5 mm is obtained. A shaft 11 is inserted into the rubber member 12, and the rubber member 12 is traverse ground to produce a rubber roller 10 having an outer diameter of 12 mm after grounding. Next, the following test is performed. A white line is drawn along the axial direction on the outer peripheral surface of the rubber member 12, and the rubber roller is placed on the metal plate MB so that the white line is directly below it. A load of 1.5 kgf is applied to each end of the shaft 11 (a total load of 3 kgf on the entire rubber roller), and the rubber roller is left at a temperature of 50° C. and a relative humidity of 90% RH for 72 hours. Then, the rubber roller is dried at a temperature of 22° C. and a relative humidity of 55% RH for 24 hours. With the white line directly below, the outer diameter of the rubber roller 10 is measured before and after the test using a laser micrometer (Mitutoyo LSM-6200). In FIG. 3, the outer diameter of the rubber roller 10 before the test is represented by D0, and the outer diameter of the rubber roller 10 after the test is represented by D1. The value obtained by subtracting the outer diameter D2 of the rubber roller 10 after the test from the outer diameter D0 of the rubber roller 10 before the test is calculated as the compression set of the rubber member 12.

[0049] The volume resistivity of the rubber member can be set according to the application. When used as a conductive member for electrophotographic equipment, the volume resistivity of the rubber member is, for example, 10 4 Ωcm or more 10 10 Ωcm or less, 10 5 Ωcm or more 10 9 It may be Ωcm or less.

[0050] The hardness of the rubber member can be set according to the application. When used as a conductive member for electrophotographic equipment, the rubber member has an Asker C hardness of, for example, 15 or more and 90 or less, or may be 15 or more and 70 or less.

[0051] 4 Rubber roller The rubber roller of the present disclosure can be obtained using the above-mentioned rubber composition. The rubber roller 10 of Fig. 1 is an example of the rubber roller of the present disclosure. The rubber roller 10 includes a shaft 11 and a rubber member 12 provided on the outer periphery of the shaft 11.

[0052] The rubber member 12 is cylindrical with a shaft insertion hole 13 in the center. The rubber roller 10 has only one layer of the rubber member 12, but may have multiple layers. The rubber member 12 may be either foamed or non-foamed. The rubber member 12 may be, for example, 0.5 mm or more and 15 mm or less.

[0053] The shaft 11 is a generally rod-shaped metal shaft. The material of the shaft 11 may be, for example, a metal with good conductivity, such as iron, stainless steel, or aluminum. The outer peripheral surface of the shaft 11, except for both ends, is covered with a rubber member 12. In addition to a metal shaft, a resin shaft or the like may be used as the shaft 11. It is preferable to use a resin shaft that is highly rigid and conductive. The resin shaft is formed, for example, by adding and dispersing a conductive agent in a highly rigid resin.

[0054] The rubber roller 10 is suitable as a component of a conductive member for electrophotographic equipment. The rubber roller 10 may be one or more selected from a charging roll, a developing roll, a transfer roll, and a toner supply roll. The rubber roller 10 may have a surface of the rubber member 12 coated depending on the application. For example, when the rubber roller 10 is a charging roll, charging properties are required, while when it is a developing roll, functions such as toner charging properties, toner releasing properties, and residual charge attenuation properties are required, so a composition according to the required functions can be prepared and coated on the surface of the rubber member 12. EXAMPLES

[0055] The present invention will be described in more detail below with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0056] 1. Preparation of Rubber Composition Rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared in the compounding ratios shown in Table 1. Details of the main raw materials in Table 1 are shown below. Rubber component 1: ECO (GECO), Epichromer CG102 manufactured by Osaka Soda (Daiso) Rubber component 2: NBR, JSR Corporation N250S (low nitrile NBR, nitrile content 19.5% by mass) Carbon black: Cancarb N990 Heavy calcium carbonate: Manufactured by Maruo Calcium Co., Ltd. - Vulcanization accelerator: Zinc oxide, Hakusui Tech Co., Ltd. Zinc oxide type 2 Foaming agent 1: ADCA, Eiwa Chemical Industry Co., Ltd. Vinihole AC#3 Foaming agent 2: OBSH, Neo Celbon N#1000S manufactured by Eiwa Kasei Co., Ltd. Processing aid: stearic acid, camellia stearic acid manufactured by Nippon Oil & Fats Co., Ltd. Vulcanizing agent: Sulfur, LANXESS Rhenogran S-80 Vulcanization accelerator 1: Thiuram vulcanization accelerator, TETD-75 manufactured by Rhein Chemie Co., Ltd. Vulcanization accelerator 2: Sulfenamide vulcanization accelerator, CM-G manufactured by Sanshin Chemical Co., Ltd. Compound represented by formula (1): 1,6-bis(N,N'-benzylthiocarbamoyldithio)hexane, Vulcuren manufactured by LANXESS Compound represented by formula (2): S-(3-aminopropyl)thiosulfate, Sumilink 100 manufactured by Sumitomo Chemical Co., Ltd.

[0057] Specifically, the rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared as follows. ECO, NBR, carbon black, heavy calcium carbonate, and vulcanization accelerator were put into a Banbury mixer and kneaded. Then, vulcanizing agent, processing aid, and vulcanization accelerator 1 and 2 were added to the obtained compound, which was further kneaded with a mixing roll and extruded into a sheet shape with a roll to prepare each rubber composition.

[0058] [Table 1]

[0059] 2. Making the rubber roller Each prepared rubber composition was fed to an extruder and extruded into a cylindrical shape with an outer diameter of 15 mm and an inner diameter of 4.5 mm. The cylindrical member was then cut to a predetermined length, attached to a temporary shaft for crosslinking, and crosslinked in a vulcanizing kettle at 160°C for 30 minutes. The temporary shaft was removed from the crosslinked cylindrical body, and the shaft of the product was inserted. Next, the outer peripheral surface was traverse-polished using a cylindrical grinding machine to produce rubber rollers of Examples 1 to 3 and Comparative Examples 1 to 3, each having an outer diameter of 12 mm after polishing.

[0060] 3. Evaluation method According to the method described in the embodiment, the compression set of the rubber members in the rubber rollers of Examples 1 to 3 and Comparative Examples 1 to 3 was measured.

[0061] Comparative Example 1 is a rubber roller obtained from a rubber composition (blank) that does not contain the compound represented by formula (1) and the compound represented by formula (2). The improvement rate (%) of the compression set of Examples 1 to 3, Comparative Example 2, and Comparative Example 3 relative to that of Comparative Example 1 was calculated by the following formula. Distortion improvement rate = ((CS0-CS1) / CS0)×100 CS0: Compression set of Comparative Example 1 (mm) CS1: Compression set (mm) of Examples 1 to 3, Comparative Example 2, and Comparative Example 3

[0062] The improvement rate of distortion in Examples 1 to 3 was evaluated according to the following criteria. A: The distortion improvement rate is 15% or more. B: The improvement rate of distortion is less than 15%.

[0063] 4.Results Examples 1 to 3 are examples using a rubber composition containing a compound represented by formula (1) and a compound represented by formula (2). All of Examples 1 to 3 were evaluated as an A in terms of the improvement rate of distortion. Comparative Example 1 is an example using a rubber composition that does not contain either the compound represented by formula (1) or the compound represented by formula (2). Comparative Example 2 is an example using a rubber composition that contains the compound represented by formula (1) but does not contain the compound represented by formula (2). Comparative Example 3 is an example using a rubber composition that does not contain the compound represented by formula (1) but contains the compound represented by formula (2). All of Comparative Examples 1 to 3 were evaluated as having a distortion improvement rate of B.

[0064] It was suggested that a rubber composition containing the compound represented by formula (1) and the compound represented by formula (2) can improve the compression set of rubber parts. Although the reason for this is unclear, it is speculated that the compound represented by formula (1) and the compound represented by formula (2) form crosslinked chains with high strength and flexibility, and increase the bonding strength between the rubber and carbon black.

[0065] 5. Effects of the embodiment In Examples 1 to 3, the compression set of the rubber members was improved. [Explanation of symbols]

[0066] 10...Rubber roller 11...Shaft 12...Rubber material 13...Shaft insertion hole

Claims

1. A rubber composition comprising a rubber component, carbon black, a compound represented by the following formula (1), and a compound represented by the following formula (2). 【Chemistry 1】 (In formula (1), R １ , R ２ , R ３ , R ４ each independently represents a monovalent organic group having 5 or more carbon atoms; and n is an integer of 1 to 20. 【Chemistry 2】 (In formula (2), R １ and R ２ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, Or, R １ and R ２ is R １ and R ２ represents an alkanediyl group having 2 to 12 carbon atoms, which may have one or more substituents and to which m represents an integer from 2 to 9; n represents 1 or 2; M ｎ＋ H ＋ Or represents a metal ion having a valence of n.

2. The rubber composition according to claim 1 , wherein the rubber component comprises at least one selected from the group consisting of NBR (nitrile butadiene rubber), ECO (epichlorohydrin rubber), and EPDM (ethylene propylene diene rubber).

3. A rubber roller using the rubber composition according to claim 1 or 2.

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