Fiber-reinforced vulcanized rubber composition and method for producing same

Abstract

A rubber composition is prepared by combining a rubber component (A) with modified cellulose nanofibers (B) to which a fluorene compound (B1) having aryl groups at the 9,9-positions is bonded. The fluorene compound (B1) may be a compound represented by the following formula (1): (wherein ring Z is an arene ring, R 1 and R 2 is a substituent, X 1 represents a heteroatom-containing functional group, k represents an integer of 0 to 4, n represents an integer of 1 or more, and p represents an integer of 0 or more). This rubber composition has excellent mechanical properties such as strength, elongation, and hardness.

Description

[Technical Field]

[0001] The present invention relates to a vulcanized rubber composition reinforced with cellulose nanofibers modified with a 9,9-bisarylfluorene skeleton, and a method for producing the same. [Background technology]

[0002] Cellulose, a fiber derived from natural products such as plants, has a low environmental impact, is a sustainable resource, and has excellent properties such as a high modulus of elasticity, high strength, and a low coefficient of linear expansion. Therefore, it is used in a wide range of applications, such as materials for paper, films, sheets, and resin composite materials (e.g., reinforcing agents for resins). Furthermore, cellulose is added to rubber compositions as a reinforcing agent to improve the mechanical properties of the rubber.

[0003] Japanese Patent Laid-Open Publication No. 2005-75856 (Patent Document 1) discloses a tire rubber composition that combines excellent low heat buildup and synthetic properties, containing 2 to 100 parts by weight of finely powdered cellulose fibers prepared from natural plant fibers and having an average particle diameter of 100 μm per 100 parts by weight of diene rubber. Japanese Patent Laid-Open Publication No. 2005-133025 (Patent Document 2) discloses a rubber composition that has excellent abrasion resistance, containing 5 to 75 parts by weight of starch and 0.1 to 40 parts by weight of bacterial cellulose with a fiber diameter of 1 μm or less per 100 parts by weight of diene rubber.

[0004] However, in these rubber compositions, the compatibility between the rubber and cellulose is low, resulting in poor rubber properties such as breaking characteristics.

[0005] Therefore, in order to improve the compatibility between rubber and cellulose, Japanese Patent No. 4581116 (Patent Document 3) discloses a vulcanized rubber composition that has excellent rupture properties and little energy loss at the interface between rubber and cellulose. The vulcanized rubber composition contains 1 to 50 parts by weight (more preferably 7 to 15 parts by weight) of chemically modified microfibril cellulose having an average fiber diameter of 4 nm to 1 μm per 100 parts by weight of a rubber component consisting of at least one of natural rubber, modified natural rubber, acrylonitrile butadiene rubber, and polybutadiene rubber. This document describes methods for chemically modifying microfibril cellulose, such as acetylation, alkyl esterification, complex esterification, β-keto esterification, and aryl carbamate formation.

[0006] However, this rubber composition cannot improve mechanical properties such as strength, elongation, hardness, etc. Furthermore, in order to improve these properties, a large amount of chemically modified cellulose is required, making it difficult to achieve all the properties at the same time. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2005-75856 A (Claim 1 and paragraph

[0007] ) [Patent Document 2] JP 2005-133025 A (Claims) [Patent Document 3] Patent No. 4581116 (Claims, paragraphs

[0003]

[0006]

[0039] ) Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a vulcanized rubber composition that can improve mechanical properties such as strength, elongation, and hardness, and a method for producing the same.

[0009] Another object of the present invention is to provide a vulcanized rubber composition that can improve heat resistance and solvent resistance, and a method for producing the same. [Means for solving the problem]

[0010] As a result of extensive research to achieve the above-mentioned objectives, the inventors discovered that by reinforcing the rubber component with modified cellulose nanofibers bonded to a compound having a 9,9-bis(aryl)fluorene skeleton, it is possible to improve the mechanical properties such as strength, elongation, and hardness of the vulcanized rubber composition, and thus completed the present invention.

[0011] That is, the vulcanized rubber composition of the present invention contains a rubber component (A) and modified cellulose nanofibers (B) to which a fluorene compound (B1) having aryl groups at the 9,9-positions is bonded. The fluorene compound (B1) may be a compound represented by the following formula (1):

[0012] [ka]

[0013] (wherein ring Z is an arene ring, R 1 and R 2 is a substituent, X 1 represents a heteroatom-containing functional group, k represents an integer of 0 to 4, n represents an integer of 1 or more, and p represents an integer of 0 or more).

[0014] In the formula (1), X 1 is the group -[(OA) m1 -Y 1 wherein A is an alkylene group, Y 1(wherein m1 represents a hydroxyl group or a glycidyloxy group, and m1 represents an integer of 0 or greater). The proportion of the fluorene compound (B1) may be about 0.01 to 33% by weight based on the total amount of the modified cellulose nanofibers (B). The average fiber diameter of the modified cellulose nanofibers (B) may be about 3 to 500 nm. The rubber component (A) may contain a diene rubber and / or an olefin rubber. The proportion of the modified cellulose nanofibers (B) may be about 0.1 to 30 parts by weight based on 100 parts by weight of the rubber component (A). The vulcanized rubber composition may further contain a reinforcing agent (C) and a processing aid (D).

[0015] The present invention also includes a method for producing a vulcanized rubber composition, which includes a kneading step of kneading a rubber component (A) with modified cellulose nanofibers (B) having fluorene compounds (B1) with aryl groups at the 9,9-positions and / or raw materials thereof, and a vulcanization step of vulcanizing the resulting kneaded composition to obtain a vulcanized rubber composition. The raw materials may be the fluorene compounds (B1) and unmodified cellulose nanofibers. In the kneading step, the modified cellulose nanofibers (B) and / or raw materials thereof, which have been dispersed in advance in a processing aid (D), may be kneaded with the rubber component (A). [Effects of the Invention]

[0016] In the present invention, the rubber component is reinforced with modified cellulose nanofibers bonded to a compound having a 9,9-bis(aryl)fluorene skeleton, allowing the modified cellulose nanofibers to be uniformly dispersed in the rubber, improving the mechanical properties of the vulcanized rubber composition, such as strength, elongation, and hardness. Furthermore, the resulting vulcanized rubber composition has high heat resistance and solvent resistance, and can suppress swelling of the rubber even when it contains processing aids such as solvents and softeners. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a scanning electron microscope (SEM) photograph of the cellulose nanofibers used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0018] The vulcanized rubber composition of the present invention contains a rubber component (A) and modified cellulose nanofibers (B) to which a fluorene compound (B1) having aryl groups at the 9,9-positions is bonded.

[0019] [Rubber component (A)] The rubber component (A) is not particularly limited, and conventional rubber components can be used. Examples of conventional rubber components include diene rubber, olefin rubber, acrylic rubber (ACM, ANM), butyl rubber (IIR), epichlorohydrin rubber (CO), polysulfide rubber (OT, EOT), urethane rubber (U), silicone rubber (Q), fluororubber (FFKM, FKM), and sulfur-containing rubber. These rubber components can be used alone or in combination. Among these rubber components, diene rubber and / or olefin rubber are preferred because of the significant improvement effect of the modified cellulose nanofibers (B).

[0020] Examples of diene rubbers include natural rubber (NR), epoxidized natural rubber, polybutadiene (e.g., butadiene rubber (BR), 1,2-polybutadiene (VBR), etc.), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and styrene-butadiene rubber (SBR). These diene rubbers may be hydrogenated rubbers (e.g., hydrogenated BR, hydrogenated NBR, hydrogenated SBR, etc.). These diene rubbers may be used alone or in combination.

[0021] Examples of olefin-based rubbers include ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), ethylene-butene rubber, ethylene-1-butene-diene rubber, propylene-1-butene-diene rubber, polyisobutylene rubber, ethylene-vinyl acetate rubber, maleic acid-modified ethylene-propylene rubber (M-EPM), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), and maleic acid-modified chlorinated polyethylene (M-CM). Examples of diene units (non-conjugated diene units) contained in olefin-based rubbers include units derived from dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, and ethylidenenorbornene. These olefin-based rubbers can be used alone or in combination.

[0022] The copolymer rubber may be a random or block copolymer, and block copolymers include copolymers having an AB type, ABA type, tapered type, or radial teleblock type structure.

[0023] Of these, diene rubbers such as SBR and NBR, and olefin rubbers such as EPDM are preferred.

[0024] The Mooney viscosity of the unvulcanized rubber component can be appropriately selected depending on the type of rubber, and may be 30 or more (e.g., about 30 to 80) in the case of diene rubber, 20 or more (e.g., about 20 to 100) in the case of olefin rubber, or 40 or more (e.g., about 40 to 80) in the case of an olefin rubber composition containing carbon black as a reinforcing agent.

[0025] In this specification and claims, Mooney viscosity can be measured in accordance with JIS K6300.

[0026] [Modified cellulose nanofibers (B)] (Fluorene compound (B1)) The fluorene compound (B1) having an aryl group at the 9,9-position serves as a functional group constituting the modified cellulose nanofiber (B), and functions as a compatibilizer or dispersant for uniformly dispersing the cellulose nanofiber in the rubber component. By uniformly dispersing the cellulose nanofiber in the rubber component (A), the mechanical properties of the vulcanized rubber composition can be significantly improved.

[0027] Such a fluorene compound may be any compound having a 9,9-bisarylfluorene skeleton, and may be, for example, a fluorene compound represented by the above formula (1).

[0028] In the formula (1), examples of the arene ring represented by ring Z include monocyclic arene rings such as a benzene ring, and polycyclic arene rings. Polycyclic arene rings include fused polycyclic arene rings (fused polycyclic hydrocarbon rings) and ring-assembled arene rings (ring-assembled aromatic hydrocarbon rings).

[0029] The fused polycyclic arene ring includes, for example, a fused bicyclic arene ring (e.g., a fused bicyclic C ring such as a naphthalene ring). 10-16 and fused bicyclic to tetracyclic arene rings such as fused tricyclic arenes (e.g., anthracene ring, phenanthrene ring, etc.). Preferred fused polycyclic arene rings include a naphthalene ring and an anthracene ring, with a naphthalene ring being particularly preferred.

[0030] Examples of the ring-assembled arene ring include biarene rings [e.g., biphenyl rings, binaphthyl rings, phenylnaphthalene rings (e.g., 1-phenylnaphthalene rings, 2-phenylnaphthalene rings, etc.)] 6-12 arene rings, etc.], terarene rings (e.g., terphenylene rings, etc.) 6-12 Examples of preferred ring-assembly arene rings include biC 6-10 Examples include an arene ring, particularly a biphenyl ring.

[0031] The two rings Z substituted at the 9-position of fluorene may be different or the same, but are usually the same ring in many cases. Among the rings Z, a benzene ring, a naphthalene ring, a biphenyl ring (particularly a benzene ring), etc. are preferred.

[0032] The substitution position of ring Z at the 9-position of fluorene is not particularly limited. For example, when ring Z is a naphthalene ring, the group corresponding to ring Z at the 9-position of fluorene may be a 1-naphthyl group, a 2-naphthyl group, or the like.

[0033] X 1 Examples of heteroatom-containing functional groups represented by the formula (1) include functional groups having at least one heteroatom selected from oxygen, sulfur, and nitrogen atoms. The number of heteroatoms contained in such functional groups is not particularly limited, but may generally be 1 to 3, and preferably 1 or 2.

[0034] Examples of the functional group include the group -[(OA) m1 -Y 1 ](where, Y 1 is a hydroxyl group, a glycidyloxy group, an amino group, an N-substituted amino group, or a mercapto group, A is an alkylene group, and m1 is an integer of 0 or more), a group -(CH2) m2 -COOR 3 (In the formula, R 3 is a hydrogen atom or an alkyl group, and m2 is an integer of 0 or more.

[0035] Group - [(OA) m1 -Y 1 ], Y 1 Examples of the N-substituted amino group include N-monoalkylamino groups (N-monoC groups) such as methylamino and ethylamino groups. 1-4 alkylamino groups), N-monohydroxyalkylamino groups such as hydroxyethylamino groups (N-monohydroxyC 1-4 alkylamino groups, etc.

[0036] The alkylene group A includes a linear or branched alkylene group, and examples of the linear alkylene group include C alkylene groups such as an ethylene group, a trimethylene group, and a tetramethylene group. 2-6 Alkylene group (preferably linear C 2-4 Alkylene groups, more preferably linear C 2-3 Examples of the branched alkylene group include a branched C alkylene group such as a propylene group, a 1,2-butanediyl group, and a 1,3-butanediyl group. 3-6 Alkylene group (preferably branched C 3-4 alkylene groups, particularly propylene groups).

[0037] m1, which indicates the number of repetitions of oxyalkylene groups (OA) (average number of moles added), can be selected from the range of 0 or an integer of 1 or more (for example, 0 to 15, preferably about 0 to 10), and may be, for example, 0 to 8 (for example, 1 to 8), preferably 0 to 5 (for example, 1 to 5), more preferably 0 to 4 (for example, 1 to 4), particularly about 0 to 3 (for example, 1 to 3), and may usually be 0 to 2 (for example, 0 or 1). When m1 is 2 or more, the types of alkylene groups A may be the same or different. Furthermore, the types of alkylene groups A in the same or different rings Z may be the same or different.

[0038] Group-(CH2) m2 -COOR 3 In R 3 The alkyl group represented by the formula (I) is a straight-chain or branched C alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, or a t-butyl group. 1-6 Examples of the alkyl group include C 1-4 Alkyl groups, especially C 1-2 It is an alkyl group. m2, which indicates the number of repeating methylene groups (average number of moles added), may be 0 or an integer of 1 or more (for example, about 1 to 6, preferably about 1 to 4, and more preferably about 1 to 2). m2 may usually be 0 or 1 to 2.

[0039] Of these, group X 1is the group -[(OA) m1 -Y 1 wherein A is an alkylene group, Y 1 is preferably a hydroxyl group or a glycidyloxy group, and m1 is an integer of 0 or more, and Y 1 is a glycidyloxy group -[(OA) m1 -Y 1 ] [wherein A is a C 2-6 Alkylene groups (e.g., C 2-4 Alkylene groups, especially C 2-3 alkylene group), and m1 is an integer of 0 to 5 (for example, 0 or 1).

[0040] In the formula (1), the group X substituted on the ring Z 1 The number n is 1 or more, preferably 1 to 3, and more preferably 1 or 2 (particularly 1). The number of substitutions n in each ring Z may be the same or different.

[0041] Group X 1 can be substituted at an appropriate position on ring Z. For example, when ring Z is a benzene ring, it is often substituted at the 2-, 3-, and 4-positions (particularly, the 3- and / or 4-positions) of the phenyl group. When ring Z is a naphthalene ring, it is often substituted at any of the 5- to 8-positions of the naphthyl group. For example, the 9-position of fluorene is substituted at the 1- or 2-position of the naphthalene ring (substitution in a 1-naphthyl or 2-naphthyl relationship), and the group X can be substituted at the 1-, 5-, 2-, 6-positions, etc. (particularly, when n is 1, 2-, 6-positions). 1 In addition, when n is 2 or more, the substitution position is not particularly limited. In addition, in the ring assembly arene ring Z, the group X 1 The substitution position of is not particularly limited, and may be substituted on the arene ring bonded to the 9-position of the fluorene and / or on the arene ring adjacent to this arene ring. For example, the 3- or 4-position of the biphenyl ring Z may be bonded to the 9-position of the fluorene, and when the 3-position of the biphenyl ring Z is bonded to the 9-position of the fluorene, the group X 1The substitution position may be any of the 2-, 4-, 5-, 6-, 2'-, 3'-, and 4'-positions, and preferably the 6-position.

[0042] In the formula (1), the substituent R 2 Examples of the alkyl group include a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an alkyl group (a linear or branched C group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a s-butyl group, or a t-butyl group), 1-10 Alkyl groups, preferably linear or branched C 1-6 Alkyl groups, more preferably linear or branched C 1-4 alkyl groups, cycloalkyl groups (cyclopentyl groups, cyclohexyl groups, etc.) 5-10 cycloalkyl groups, aryl groups [phenyl groups, alkylphenyl groups (methylphenyl (tolyl) groups, dimethylphenyl (xylyl) groups, etc.), biphenyl groups, naphthyl groups, etc.] 6-12 aryl group, etc.], aralkyl group (benzyl group, phenethyl group, etc. C 6-10 Aryl-C 1-4 alkyl groups, alkoxy groups (e.g., methoxy, ethoxy, propoxy, n-butoxy, isobutoxy, t-butoxy, and other linear or branched C 1-10 alkoxy groups, cycloalkoxy groups (e.g., cyclohexyloxy groups, etc.) 5-10 cycloalkyloxy groups, aryloxy groups (e.g., phenoxy groups, etc.) 6-10 aryloxy group, aralkyloxy group (e.g., C 6-10 Aryl-C 1-4 alkyloxy group, alkylthio group (e.g., methylthio group, ethylthio group, propylthio group, n-butylthio group, t-butylthio group, etc.) 1-10 alkylthio groups, cycloalkylthio groups (e.g., cyclohexylthio groups, etc.) 5-10 cycloalkylthio groups, arylthio groups (e.g., thiophenoxy groups, etc.) 6-10 arylthio groups, aralkylthio groups (e.g., C6-10 Aryl-C 1-4 alkylthio groups), acyl groups (e.g., acetyl groups, etc. 1-6 Examples include an acyl group, a nitro group, and a cyano group.

[0043] These substituents R 2 Representative examples of the substituent R include a halogen atom, a hydrocarbon group (an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group), an alkoxy group, an acyl group, a nitro group, a cyano group, and a substituted amino group. 2 As the alkyl group, linear or branched C 1-4 Alkoxy groups, etc.), in particular alkyl groups (especially straight or branched C groups such as methyl groups, 1-4 The substituent R is preferably an alkyl group. 2 is an aryl group, the substituent R 2 may form the ring assembly arene ring together with the ring Z. 2 The types of may be the same or different in the same or different rings Z.

[0044] Substituent R 2 The number p can be appropriately selected depending on the type of ring Z, and may be, for example, an integer of about 0 to 8, an integer of 0 to 4, preferably an integer of 0 to 3 (e.g., 0 to 2), and more preferably 0 or 1. In particular, when p is 1, ring Z is a benzene ring, a naphthalene ring, or a biphenyl ring, and substituent R 2 may be a methyl group.

[0045] Substituent R 1 Examples of the alkyl group include a cyano group, a halogen atom (such as a fluorine atom, a chlorine atom, or a bromine atom), a carboxyl group, and an alkoxycarbonyl group (such as a methoxycarbonyl group). 1-4 alkoxy-carbonyl group, etc.), alkyl group (e.g., methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, etc. 1-6 alkyl groups), aryl groups (e.g., C 6-10 aryl groups).

[0046] These substituents R 1 Among them, linear or branched C 1-4 Alkyl groups (especially C groups such as methyl groups) 1-3 alkyl group), carboxyl group or C 1-2 An alkoxy-carbonyl group, a cyano group, or a halogen atom is preferred. The number of substitutions k is an integer of 0 to 4 (for example, 0 to 3), preferably an integer of 0 to 2 (for example, 0 or 1), particularly 0. The numbers of substitutions k may be the same or different, and when k is 2 or more, the number of substituents R 1 The types of substituents R substituted on the two benzene rings of the fluorene ring may be the same or different. 1 The types of the substituents R may be the same or different. 1 The substitution position of is not particularly limited, and may be, for example, the 2- to 7-position (such as the 2-, 3- and / or 7-position) of the fluorene ring.

[0047] Among these, preferred fluorene compounds are those containing a group X 1 However, the group -[(OA) m1 -Y 1 ](where, Y 1 represents a hydroxyl group), for example, 9,9-bis(hydroxy C such as 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(6-hydroxy-2-naphthyl)fluorene, and 9,9-bis(5-hydroxy-1-naphthyl)fluorene. 6-12 9,9-bis(di- or trihydroxyphenyl) fluorene, such as 9,9-bis(3,4-dihydroxyphenyl) fluorene; 6-12 aryl)fluorene; 9,9-bis(C 1-4 Alkyl-Hydroxy C 6-12 aryl)fluorene; 9,9-bis(C aryl)fluorene, such as 9,9-bis(3-phenyl-4-hydroxyphenyl)fluorene and 9,9-bis(4-phenyl-3-hydroxyphenyl)fluorene; 6-12 Aryl-Hydroxy C 6-12aryl)fluorene; 9,9-bis(hydroxy(poly)C such as 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene, and 9,9-bis[5-(2-hydroxyethoxy)-1-naphthyl]fluorene 2-4 Alkoxy-C 6-12 aryl)fluorene; 9,9-bis(C 1-4 Alkyl-hydroxy(poly)C 2-4 Alkoxy-C 6-12 aryl)fluorene; 9,9-bis(C such as 9,9-bis[3-phenyl-4-(2-hydroxyethoxy)phenyl]fluorene and 9,9-bis[4-phenyl-3-(2-hydroxyethoxy)phenyl]fluorene 6-12 Aryl-hydroxy(poly)C 2-4 Alkoxy-C 6-12 aryl)fluorene and the like.

[0048] Group X 1 However, the group -[(OA) m1 -Y 1 ](where, Y 1 represents a glycidyloxy group), preferred fluorene compounds include 9,9-bis(glycidyloxyaryl)fluorenes such as 9,9-bis(glycidyloxy C aryl)fluorene, for example, 9,9-bis(3-glycidyloxyphenyl)fluorene, 9,9-bis(4-glycidyloxyphenyl)fluorene, 9,9-bis(5-glycidyloxy-1-naphthyl)fluorene, and 9,9-bis(6-glycidyloxy-2-naphthyl)fluorene. 6-109,9-bis(glycidyloxy(poly)aryl)fluorene; 9,9-bis(glycidyloxy(poly)alkoxyaryl)fluorenes, for example, 9,9-bis(4-(2-glycidyloxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-glycidyloxypropoxy)phenyl)fluorene, 9,9-bis(5-(2-glycidyloxyethoxy)-1-naphthyl)fluorene, 9,9-bis(6-(2-glycidyloxyethoxy)-2-naphthyl)fluorene, etc. 2-4 Alkoxy C 6-10 aryl)fluorene; 9,9-bis(alkyl-glycidyloxyaryl)fluorene, for example, 9,9-bis(C aryl)fluorene, such as 9,9-bis(3-methyl-4-glycidyloxyphenyl)fluorene; 1-4 Alkyl-glycidyloxy C 6-10 aryl)fluorenes; 9,9-bis(alkyl-glycidyloxy(poly)alkoxyaryl)fluorenes, for example, 9,9-bis(C 3-methyl-4-(2-glycidyloxyethoxy)phenyl)fluorene; 1-4 Alkyl-glycidyloxy(poly)C 2-4 Alkoxy C 6-10 aryl)fluorene; 9,9-bis(aryl-glycidyloxyaryl)fluorene, for example, 9,9-bis(C aryl)fluorene, such as 9,9-bis(3-phenyl-4-glycidyloxyphenyl)fluorene; 6-10 Aryl-glycidyloxy C 6-10 aryl)fluorene; 9,9-bis(aryl-glycidyloxy(poly)alkoxyaryl)fluorene, for example, 9,9-bis(C 3-phenyl-4-(2-glycidyloxyethoxy)phenyl)fluorene; 6-10 Aryl-glycidyloxy(poly)C 2-4 Alkoxy C 6-10 9,9-bis(di(glycidyloxy)aryl)fluorenes, such as 9,9-bis(di(glycidyloxy)aryl)fluorene; 6-109,9-bis(di(glycidyloxy(poly)alkoxy)aryl)fluorenes, for example, 9,9-bis(di(glycidyloxy(poly)alkoxy)aryl)fluorene, such as 9,9-bis(3,4-di(2-glycidyloxyethoxy))phenyl)fluorene; 2-4 Alkoxy)C 6-10 aryl)fluorene and the like.

[0049] These fluorene compounds (B1) can be used alone or in combination. The term "(poly)alkoxy" is used to mean both an alkoxy group and a polyalkoxy group.

[0050] (cellulose nanofiber) The cellulose nanofibers (or cellulose nanofibers) constituting the modified cellulose nanofibers (B) are cellulose fibers obtained by microfibrillating (or microrefining) cellulose (cellulose raw material) to the nano-order, or nanometer-sized cellulose fibers derived from microorganisms. Examples of the cellulose nanofibers include pulps with low contents of non-cellulose components such as lignin and hemicellulose, such as pulps produced from plant-derived cellulose raw materials (e.g., wood [e.g., conifers (pine, fir, spruce, hemlock, cedar, etc.)], broad-leaved trees (beech, birch, poplar, maple, etc.)], herbaceous plants [hemp (hemp, flax, Manila hemp, ramie, etc.), straw, bagasse, Mitsumata, etc.], seed hair fibers (cotton linters, bombax cotton, kapok, etc.), bamboo, sugarcane, etc.), animal-derived cellulose raw materials (e.g., sea squirt cellulose), and bacterial-derived cellulose raw materials (e.g., the cellulose contained in nata de coco). These cellulose nanofibers can be used alone or in combination. Among these cellulose nanofibers, cellulose nanofibers derived from wood pulp (e.g., softwood pulp, hardwood pulp, etc.) and pulp derived from seed hair fibers (e.g., cotton linter pulp) are preferred. Note that the pulp may be mechanical pulp obtained by mechanically treating pulp material, but chemical pulp obtained by chemically treating pulp material is preferred because it has a low content of non-cellulose components.

[0051] The average fiber diameter and average fiber length of the cellulose nanofibers (or raw cellulose nanofibers) can be selected so that the average fiber diameter and average fiber length of the modified cellulose nanofibers fall within the ranges described below. The average fiber diameter, average fiber length, and ratio of the average fiber length to the average fiber diameter (aspect ratio) of the cellulose nanofibers may be the same as, and are usually approximately the same as, the ranges of the modified cellulose nanofibers described below.

[0052] The cellulose nanofibers may be highly crystalline cellulose (or cellulose fibers), and the degree of crystallinity of the cellulose may be, for example, 40 to 100% (e.g., 50 to 100%), preferably 60 to 100%, and more preferably 70 to 100% (particularly 75 to 100%), and typically the degree of crystallinity may be 60% or more (e.g., 60 to 99%). Furthermore, examples of the cellulose crystal structure include type I, type II, type III, and type IV, with type I crystal structure being preferred because of its excellent linear expansion properties and elastic modulus.

[0053] (Modified cellulose nanofibers (B) and their manufacturing method) The modified cellulose nanofibers (or altered cellulose nanofibers) (B) are cellulose derivatives in which the cellulose nanofibers and the fluorene compound (B1) are bonded together.

[0054] The form of chemical modification (or bonding) of the modified cellulose nanofibers (B) is not particularly limited, and for example, when the fluorene compound (B1) is a fluorene compound represented by the above formula (1), it can be appropriately selected depending on the type of reactive group (heteroatom-containing functional group) of the fluorene compound (B1). Specifically, in the above formula (1), Y 1 When Y is a hydroxyl group, it may be an ether bond and / or an ester bond between the hydroxyl group and / or carboxyl group of the cellulose nanofiber and the hydroxyl group of the fluorene compound represented by formula (1), 1When is a glycidyloxy group, it may be an ether bond and / or an ester bond between the hydroxyl group and / or carboxyl group of the cellulose nanofiber and the glycidyl group of the fluorene compound represented by formula (1). Note that the carboxyl group of the cellulose nanofiber may be formed during the production process of pulp, etc.

[0055] The modified cellulose nanofibers (B) may be produced by reacting raw cellulose nanofibers with the fluorene compound (B1) in the presence of a specific catalyst, or by reacting the raw cellulose nanofibers with the fluorene compound (B1) in the rubber component (A) during the process of kneading them.

[0056] The proportion of the raw cellulose nanofibers can be selected depending on the reactive groups of the fluorene compound (B1), and can be selected, for example, from a range of about 0.1 to 500 parts by weight (e.g., 1 to 300 parts by weight) per 100 parts by weight of the fluorene compound (B1), and may be, for example, about 5 to 200 parts by weight (particularly, 10 to 150 parts by weight).

[0057] When using a catalyst, the catalyst can also be selected according to the reactive group of the fluorene compound, and when the reactive group is a hydroxyl group, an acid catalyst can be used.As the acid catalyst, Bronsted acid, for example, inorganic acid such as sulfuric acid, hydrochloric acid, phosphoric acid, etc., organic acid such as p-toluenesulfonic acid, solid acid [for example, heteropolyacid (tungsten-based heteropolyacid, molybdenum-based heteropolyacid, etc.), cation exchange resin (strong acid cation exchange resin with sulfonic acid group, fluorine-containing cation exchange resin with sulfonic acid group, weak acid cation exchange resin with carboxylic acid group, etc.)] can be mentioned.These acid catalysts can be used alone or in combination of two or more.

[0058] When the reactive group is a glycidyl group, a base catalyst may be used. The base catalyst may be either an inorganic base or an organic base. Examples of inorganic bases include alkali metal hydroxides (sodium hydroxide, potassium hydroxide, etc.) and alkali metal carbonates. Examples of organic bases include tertiary amines, such as trialkylamines (trimethylamine, triethylamine, etc.), alkanolamines (triethanolamine, dimethylaminoethanol, etc.), heterocyclic amines (N-methylmorpholine, etc.), hexamethylenetetramine, diazabicycloundecene (DBU), diazabicyclononene (DBN), and 1,4-diazabicyclo[2.2.2]octane (DABCO). These base catalysts may be used alone or in combination.

[0059] The amount of catalyst used can be selected depending on the type of catalyst, but can be appropriately selected, for example, from a range of about 0.01 to 100 parts by weight per 100 parts by weight of raw cellulose nanofibers, and may typically be about 0.01 to 20 parts by weight (e.g., 0.1 to 18 parts by weight), preferably 0.5 to 18 parts by weight (e.g., 1 to 17 parts by weight), and more preferably 3 to 15 parts by weight (particularly 5 to 15 parts by weight).

[0060] When a catalyst is used, the reaction can be carried out in the absence of an organic solvent, but is usually carried out in the presence of an organic solvent. The organic solvent may be impregnated into the raw cellulose nanofibers, but the reaction is often carried out in a dispersion system in which the raw cellulose nanofibers are dispersed in an organic solvent. Reacting the raw cellulose nanofibers with the fluorene compound (B1) in a dispersion system in which the raw cellulose nanofibers are dispersed in an organic solvent ensures a uniform reaction. The modified cellulose nanofibers (B) obtained by this method are easy to handle and disperse.

[0061] Drying raw cellulose nanofibers (particularly microfibrillated fibers and nanofibers with an average fiber diameter on the nanometer scale) can result in the fibers becoming entangled and unable to be redispersed. For this reason, raw cellulose nanofibers are typically sold commercially as water-impregnated or aqueous dispersions. Such aqueous dispersions can be prepared by a conventional solvent substitution method in which the water in the aqueous dispersion is replaced with an organic solvent. For example, a water-soluble solvent is added to and mixed with the aqueous dispersion of raw cellulose nanofibers, the raw cellulose nanofibers are separated (or the solvent is removed), and then another organic solvent is added and mixed, repeating this process. When using a water-soluble organic solvent with a boiling point higher than that of water, solvent substitution can be achieved by removing the water by distillation (including azeotropic distillation).

[0062] Examples of water-soluble organic solvents include alcohols (C such as methanol, ethanol, propanol, and isopropanol) 1-4 alkanols, etc.), ethers (cyclic ethers such as dioxane and tetrahydrofuran), ketones (acetone, etc.), amides (dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, etc.), sulfoxides (dimethyl sulfoxide, etc.), alkanediols (e.g., C 12 alkyl ethers such as ethylene glycol and propylene glycol, etc.), 2-4 alkanediols), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), carbitols (ethyl carbitol, etc.), carbonates (ethylene carbonate, propylene carbonate, dimethyl carbonate, etc.), etc. These solvents may be used alone or in combination of two or more.

[0063] In addition, in the cellulose-containing dispersion in which the solvent is replaced with a water-soluble organic solvent, the water-soluble organic solvent can also be replaced with a water-insoluble organic solvent in the same manner as described above. Examples of water-insoluble organic solvents include ethers (dialkyl ethers such as diethyl ether and diisopropyl ether), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, etc.), nitriles (benzonitrile, etc.), cellosolve acetates, carbitol acetates, hydrocarbons (aliphatic hydrocarbons such as hexane, octane, cyclohexane, etc., aromatic hydrocarbons such as toluene), halogenated hydrocarbons (dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethylene, etc.). These water-insoluble organic solvents can be used alone or in combination of two or more.

[0064] Among these organic solvents, aprotic solvents, particularly aprotic polar solvents (for example, ethers, ketones, amides, sulfoxides, etc.) are preferred.

[0065] Solubility parameter (SP value, (cal / cm)) of organic solvent (e.g., aprotic polar solvent) 2 ) may be about 8 to 15 (for example, 8.5 to 15), and usually may be about 9 to 14.5 (for example, 10 to 14.5).

[0066] The solids concentration of the raw cellulose nanofibers in the dispersion may be, for example, 0.01 to 30% by weight (e.g., 0.1 to 20% by weight), preferably 1 to 15% by weight, and more preferably 3 to 12% by weight (e.g., 5 to 10% by weight). If the solids concentration is too low, there is a risk of a decrease in reaction efficiency.

[0067] When a catalyst is used, the reaction may be carried out under reduced pressure, but is usually carried out under elevated pressure or normal pressure. The reaction temperature can be appropriately selected depending on the boiling point of the solvent, and may be, for example, about 50 to 200°C (e.g., 70 to 170°C), preferably about 80 to 150°C (e.g., 100 to 130°C). The reaction may be carried out under reflux of the solvent. The reaction time is not particularly limited, and is, for example, about 10 minutes to 48 hours (e.g., 30 minutes to 24 hours). The reaction may be carried out in air or in an inert gas atmosphere (such as nitrogen, a rare gas such as argon, etc.) with stirring.

[0068] The reaction may be carried out while stirring the reaction system, or by using cellulose or fibers that are not nanometer-sized (for example, fibers with an average fiber diameter of micrometers, pulp fibers, etc.) as the raw cellulose fibers and applying mechanical shear force to the cellulose or fibers to obtain modified cellulose nanofibers by pulping the cellulose. Furthermore, the modified cellulose fibers may be pulverized by defibration after the reaction is completed.

[0069] The modified cellulose nanofibers (B) produced by the reaction using a catalyst may be separated and purified by conventional methods (e.g., centrifugation, filtration, concentration, extraction, etc.). For example, a solvent capable of dissolving at least the fluorene compound (B1) may be added to the reaction mixture, and the unreacted fluorene compound may be removed by a conventional separation method such as centrifugation, filtration, or extraction, followed by separation and purification. The separation procedure may be repeated multiple times (e.g., about 2 to 5 times). Furthermore, the separated and purified modified cellulose may be dried under heat, reduced pressure, or normal pressure to obtain modified cellulose fibers in powder form.

[0070] Furthermore, when the modified cellulose that has been purified by repeatedly removing the unreacted fluorene compound using the above-mentioned separation method or the like is analyzed by a method such as Raman analysis, peaks derived from cellulose and peaks derived from the fluorene compound are present, confirming that the fluorene compound is bonded to the cellulose.

[0071] On the other hand, when the modified cellulose nanofibers are produced by kneading in an unvulcanized rubber component, the modified cellulose nanofibers are obtained during the production process of a vulcanized rubber composition, as described below.

[0072] (Characteristics of modified cellulose nanofibers (B)) The modified cellulose nanofibers (B) obtained using a catalyst are usually in a powder form and are easy to handle. Furthermore, even if the modification ratio (bonding amount) of the fluorene compound (B1) is relatively small, the modified cellulose nanofibers (B) may be in a powder form.

[0073] The proportion (modification rate) of the fluorene compound (B1) bound to the cellulose nanofibers can be selected from the range of about 0.01 to 33% by weight (for example, 1 to 25% by weight) relative to the total amount of the modified cellulose nanofibers (B). In particular, the group X of the fluorene compound (B1) 1 The base is -[(OA) m1 -Y 1 ](where, Y 1 represents a hydroxyl group), the modification rate can be selected from a range of about 0.01 to 30% by weight relative to the total amount of the modified cellulose nanofibers (B), and may be, for example, about 0.1 to 30% by weight, preferably about 0.5 to 25% by weight (e.g., 1 to 25% by weight), and more preferably about 2 to 20% by weight (particularly about 3 to 20% by weight). 1 The base is -[(OA) m1 -Y 1 ](where, Y 1 represents a glycidyloxy group), the modification rate may be about 0.01 to 33% by weight (for example, 0.1 to 30% by weight), preferably about 1 to 25% by weight (for example, 2 to 25% by weight), and more preferably about 3 to 20% by weight (particularly about 5 to 20% by weight).

[0074] If the modification rate is too high, there is a risk that properties such as dispersibility in aqueous solvents and a low coefficient of linear thermal expansion may be reduced, whereas if the modification rate is too low, there is a risk that a powder form cannot be formed, which may lead to reduced handleability and reduced dispersibility (or miscibility) with the rubber component in the rubber composition. The modification rate can be measured by the method described in the examples below.

[0075] The average fiber diameter of the modified cellulose nanofibers (B) may be, for example, 1 to 1000 nm (e.g., 3 to 800 nm), preferably 4 to 500 nm (e.g., 5 to 300 nm), and more preferably about 10 to 200 nm (particularly 15 to 100 nm). If the average fiber diameter is too large, there is a risk that the properties of the rubber composition, such as strength, may be reduced. The maximum fiber diameter of the cellulose nanofibers may be, for example, 3 to 1000 nm (e.g., 4 to 900 nm), preferably 5 to 700 nm (e.g., 10 to 500 nm), and more preferably about 15 to 400 nm (particularly 20 to 300 nm). In many cases, the cellulose nanofibers do not substantially contain cellulose fibers with a fiber diameter of micrometer size.

[0076] The average fiber length of the modified cellulose nanofibers (B) can be selected, for example, from the range of about 0.01 to 500 μm (e.g., 0.1 to 400 μm), and may usually be 1 μm or more (e.g., 5 to 300 μm), preferably 10 μm or more (e.g., 20 to 200 μm), and more preferably 30 μm or more (particularly 50 to 150 μm). If the average fiber length is too short, the mechanical properties of the rubber composition may be reduced, and conversely, if it is too long, dispersibility in the rubber composition may be reduced.

[0077] The ratio of the average fiber length to the average fiber diameter (aspect ratio) of the modified cellulose nanofibers (B) may be, for example, 5 or more (e.g., about 5 to 10,000), preferably 10 or more (e.g., about 10 to 5,000), more preferably 20 or more (e.g., about 20 to 3,000), particularly 50 or more (e.g., about 50 to 2,000), or may be 100 or more (e.g., about 100 to 1,000), or even 200 or more (e.g., about 200 to 800). If the aspect ratio is too small, the reinforcing effect on the rubber component decreases, while if the aspect ratio is too large, uniform dispersion becomes difficult and the fibers may be prone to decomposition (or damage).

[0078] In this specification and claims, the average fiber diameter, average fiber length, and aspect ratio of the modified cellulose nanofibers (B) (or raw cellulose nanofibers) may be calculated by randomly selecting 50 fibers from a scanning electron microscope image and averaging them.

[0079] The modified cellulose nanofibers (B) have a low moisture content, possibly due to the improved hydrophobicity caused by the modification with the fluorene compound (B1). Specifically, the moisture content may be 0 to 7% by weight (e.g., 0 to 5% by weight), preferably 0.1 to 5% by weight, and more preferably 0.3 to 3% by weight, when left for one day and night under conditions of a temperature of 25°C and a humidity of 60%. The moisture content can be measured using a near-infrared analyzer or the like.

[0080] The bulk density (apparent density) of the modified cellulose nanofibers (B) may be, for example, 0.01 to 0.7 g / ml, preferably 0.05 to 0.5 g / ml, and more preferably about 0.1 to 0.3 g / ml, when measured in accordance with JIS K7365-1999 under conditions of a temperature of 25°C and a humidity of 60%. The bulk density P can be calculated by placing a predetermined weight W of modified cellulose nanofibers in a measuring cylinder, measuring the volume V, and using the formula P=W / V.

[0081] The modified cellulose nanofibers (B) may have high fluidity, and the angle of repose, when measured in accordance with JIS R9301-2-2 at a temperature of 25°C and a humidity of 60%, may be, for example, 20 to 45°, preferably 25 to 40°, and more preferably about 30 to 35°. If the fluidity is too high, the handleability may decrease, and conversely, if the fluidity is too low, the dispersibility may decrease.

[0082] The modified cellulose nanofibers (B) maintain the nanofiber form without forming a viscous liquid, and therefore have a relatively high molecular weight (or degree of polymerization), and the viscosity-average degree of polymerization may be, for example, about 100 to 10,000, preferably about 200 to 5,000, and more preferably about 300 to 2,000.

[0083] The viscosity-average degree of polymerization can be measured using the viscosity method described in TAPPI T230. Specifically, 0.04 g of modified cellulose nanofibers (or raw cellulose nanofibers) is precisely weighed, 10 mL of water and 10 mL of 1 M copper ethylenediamine aqueous solution are added, and the mixture is stirred for approximately 5 minutes to dissolve the modified cellulose. The resulting solution is placed in an Ubbelohde-type viscometer, and the flow rate is measured at 25°C. A mixture of 10 mL of water and 10 mL of 1 M copper ethylenediamine aqueous solution is used as a blank. The intrinsic viscosity [η] calculated based on these measurements can be used to calculate the viscosity-average degree of polymerization according to the following formula described in the Wood Science Experiment Manual (edited by the Japan Wood Research Society, Bun'ei-do Publishing).

[0084] Viscosity average degree of polymerization = 175×[η]

[0085] Furthermore, to effectively exhibit the properties of the modified cellulose nanofibers (B) in the vulcanized rubber composition of the present invention (e.g., low linear thermal expansion, strength, heat resistance, etc.), highly crystalline modified cellulose nanofibers are preferred. As described above, since the modified cellulose can maintain the crystallinity of the cellulose nanofibers, the crystallinity of the modified cellulose nanofibers (B) can be determined by directly referring to the numerical value of the cellulose nanofibers. For example, the crystallinity of the modified cellulose may be about 40 to 100% (e.g., 50 to 100%), preferably about 60 to 100% (e.g., 65 to 100%), and more preferably about 70 to 100% (particularly 75 to 100%). Typically, the crystallinity may be 60% or higher (e.g., about 75 to 99%). If the crystallinity is too low, properties such as linear thermal expansion and strength may be reduced. Examples of cellulose crystalline structures include type I, type II, type III, and type IV. Type I crystal structure, which exhibits low linear expansion and a high modulus of elasticity, is preferred. The crystallinity can be measured using a powder X-ray diffractometer ("Ultima IV" manufactured by Rigaku Corporation) or the like.

[0086] The proportion of the modified cellulose nanofibers (B) can be selected from the range of about 0.1 to 30 parts by weight per 100 parts by weight of the rubber component (A), for example, about 0.2 to 25 parts by weight, preferably about 0.3 to 20 parts by weight, and more preferably about 0.5 to 15 parts by weight (particularly about 1 to 10 parts by weight). Furthermore, in the present invention, even a small proportion of the modified cellulose nanofibers (B) can improve mechanical properties and heat resistance, and the proportion of the modified cellulose nanofibers (B) may be, for example, about 0.1 to 10 parts by weight, preferably about 0.3 to 7 parts by weight, and more preferably about 0.5 to 5 parts by weight (particularly about 1 to 3 parts by weight) per 100 parts by weight of the rubber component (A). If the proportion of the modified cellulose nanofibers (B) is too low, the mechanical properties of the rubber composition may be reduced, while if it is too high, the moldability of the rubber composition may be reduced.

[0087] In the present invention, the mechanical properties of the rubber composition can be improved by adding modified cellulose nanofibers (B) to the rubber component (A) in the above-mentioned ratio. Furthermore, the heat resistance of the vulcanized rubber composition can be improved by adding unmodified cellulose nanofibers, which are the raw material for the modified cellulose nanofibers (B), to the rubber component (A). The proportion of the cellulose nanofibers can be selected from the same range as the amount of the modified cellulose nanofibers (B) added (the above-mentioned proportion in the composition). From the viewpoint of significantly improving the mechanical properties of the vulcanized rubber composition, modified cellulose nanofibers (B) are preferred over unmodified cellulose nanofibers.

[0088] [Reinforcing agent (C)] The vulcanized rubber composition of the present invention may further contain a reinforcing agent (C) in addition to the rubber component (A) and the modified cellulose nanofibers (B) in order to improve mechanical properties such as hardness and strength.

[0089] The reinforcing agent (C) may be any conventional reinforcing agent, including, for example, particulate reinforcing agents (carbonaceous materials such as carbon black and graphite; metal oxides such as calcium oxide, magnesium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, and aluminum oxide (alumina); metal silicates such as calcium silicate and aluminum silicate; metal carbides such as silicon carbide and tungsten carbide; metal nitrides such as titanium nitride, aluminum nitride, and boron nitride; metal carbonates such as magnesium carbonate and calcium carbonate; metal sulfates such as calcium sulfate and barium sulfate; mineral materials such as zeolite, diatomaceous earth, calcined diatomaceous earth, activated clay, silica, talc, mica, kaolin, sericite, bentonite, montmorillonite, smectite, and clay), and fibrous reinforcing agents (inorganic fibers such as glass fiber, carbon fiber, boron fiber, whiskers, and wollastonite; organic fibers such as polyester fiber, polyamide fiber, and cellulose fiber). These reinforcing agents may be used alone or in combination.

[0090] The cellulose fibers in the reinforcing agent may be cellulose nanofibers. Furthermore, the cellulose nanofibers may be cellulose nanofibers that remain unreacted with the fluorene compound (B1) when modified cellulose nanofibers are produced by reacting raw cellulose nanofibers with the fluorene compound (B1) during the kneading process.

[0091] Among these reinforcing agents, particulate reinforcing agents (particularly particulate inorganic reinforcing agents) such as carbon black, calcium carbonate, and silica are commonly used, and carbon black, calcium carbonate, and silica are preferred, with carbon black being particularly preferred, because they can significantly improve the mechanical properties of the rubber composition when combined with the modified cellulose nanofibers (B). In the present invention, the modified cellulose nanofibers (B) not only have high dispersibility in the rubber component themselves, but also have high compatibility with particulate reinforcing agents (particularly particulate inorganic reinforcing agents such as carbon black), thereby improving the dispersibility of the particulate reinforcing agents.

[0092] Examples of carbon black include acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, coated carbon black, grafted carbon black, etc. These carbon blacks can be used alone or in combination.

[0093] The calcium carbonate may be calcium carbonate that has been surface-treated with a surface treatment agent such as rosin acid.

[0094] Examples of silica include dry white carbon, wet white carbon, colloidal silica, precipitated silica, etc. These silicas can be used alone or in combination.

[0095] The shape of the granular inorganic reinforcing agent is not particularly limited, and may be spherical, ellipsoidal, polyhedral (e.g., cubic, rectangular, tetrahedral (pyramidal)), flat (plate-like, scale-like, or flake-like), layered, rod-like, needle-like, irregular, or the like. The granular inorganic reinforcing agent may also be porous. Of these, an isotropic shape such as a substantially spherical shape is preferred.

[0096] The average particle size (number average primary particle size) of the granular inorganic reinforcing agent is, for example, about 1 to 1000 nm, preferably about 3 to 300 nm, and more preferably about 5 to 100 nm (particularly about 10 to 50 nm). If the particle size of the granular inorganic reinforcing agent is too large, the mechanical properties of the vulcanized rubber composition may be reduced, whereas if the particle size is too small, it may be difficult to disperse uniformly.

[0097] The average particle size (number average primary particle size) of the carbon black can be selected from the range of about 5 to 200 nm, for example, about 10 to 150 nm, preferably about 15 to 100 nm, and more preferably about 20 to 80 nm (particularly about 30 to 50 nm). If the average particle size of the carbon black is too small, uniform dispersion may be difficult, while if it is too large, the mechanical properties of the rubber composition may be reduced.

[0098] In this specification and claims, the average particle size of the particulate inorganic reinforcing agent can be measured by a conventional method, for example, based on a scanning electron microscope (SEM) or transmission electron microscope (TEM) photograph.

[0099] The proportion of the reinforcing agent (C) can be selected from the range of about 10 to 300 parts by weight per 100 parts by weight of the rubber component (A), and is, for example, about 20 to 200 parts by weight, preferably about 30 to 150 parts by weight, and more preferably about 50 to 100 parts by weight (particularly about 60 to 80 parts by weight). If the proportion of the reinforcing agent is too low, the effect of improving the mechanical properties of the vulcanized rubber composition may be reduced, and conversely, if it is too high, the elongation, strength, etc. of the vulcanized rubber composition may be reduced.

[0100] [Processing aids (D)] The vulcanized rubber composition of the present invention may further contain a processing aid (D) in addition to the rubber component (A) and the modified cellulose nanofibers (B) in order to improve moldability and the like.

[0101] The processing aid (D) is not particularly limited as long as it is an additive that is compatible with the rubber component (A) and can reduce the viscosity of the unvulcanized rubber composition, and examples thereof include solvents (e.g., aliphatic hydrocarbons such as hexane and cyclohexane; aromatic hydrocarbons such as benzene, xylene, and toluene; alkanols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; halogenated hydrocarbons such as chloroform and trichloroethylene; ethers such as ethyl ether and tetrahydrofuran; esters such as ethyl acetate; amides such as dimethylformamide; and sulfur compounds such as carbon disulfide), softeners (oils such as paraffinic oil, naphthenic oil, and process oil), and plasticizers (stearic acid, metal stearates, waxes, paraffins, and fatty acid amides). These processing aids can be used alone or in combination.

[0102] Among these processing aids, solvents such as toluene, softeners such as naphthenic oils and process oils, and plasticizers such as stearic acid are commonly used.

[0103] In the present invention, even when these processing aids are compounded to improve moldability, the modified cellulose nanofibers (B) contained in the composition can prevent the processing aid (D) from causing a decrease in the mechanical properties of the vulcanized rubber composition (particularly, a vulcanized rubber composition containing an olefin-based rubber such as EPDM).

[0104] The proportion of the processing aid (D) can be appropriately selected depending on the type of rubber component (A) and can be selected from a range of about 0.1 to 500 parts by weight per 100 parts by weight of the rubber component (A), for example, 0.5 to 400 parts by weight (e.g., 1 to 300 parts by weight), preferably 1 to 200 parts by weight, and more preferably about 3 to 100 parts by weight. When the rubber component (A) is an olefin-based rubber, the proportion of the processing aid (D) may be, for example, 10 to 200 parts by weight, preferably 20 to 150 parts by weight, and more preferably about 30 to 100 parts by weight per 100 parts by weight of the rubber component (A). If the proportion of the processing aid (D) is too low, the effect of improving moldability may be reduced, and conversely, if it is too high, the mechanical properties of the vulcanized rubber composition may be reduced.

[0105] [Vulcanizing agent (E)] The vulcanized rubber composition of the present invention usually contains a vulcanizing agent (E). As the vulcanizing agent (E), a conventional vulcanizing agent can be used depending on the type of rubber component (A). The vulcanizing agent (E) includes sulfur-based vulcanizing agents and organic peroxides.

[0106] Examples of sulfur-based vulcanizing agents include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, surface-treated sulfur, sulfur chlorides (such as sulfur monochloride and sulfur dichloride), morpholine disulfide, and alkylphenol disulfide.

[0107] Examples of organic peroxides include diacyl peroxides such as dilauroyl peroxide, dibenzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 1,1-di-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, and 1,3-bis(t-butylperoxy-isopropyl)benzene; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, and diisopropylbenzene hydroperoxide; and peroxy esters such as n-butyl-4,4-di-t-butylperoxyvalerate and 2,5-dimethylhexane-2,5-di(peroxylbenzoate).

[0108] These vulcanizing agents can be used alone or in combination of two or more. Among these, sulfur and dialkyl peroxides such as dicumyl peroxide are commonly used.

[0109] The proportion of the vulcanizing agent (E) may be, for example, about 0.1 to 10 parts by weight, preferably about 0.5 to 8 parts by weight, and more preferably about 0.6 to 5 parts by weight (particularly about 0.8 to 3 parts by weight) relative to 100 parts by weight of the rubber component (A).

[0110] [Vulcanization aid (F)] The vulcanized rubber composition of the present invention may further contain a vulcanization aid (F) to accelerate vulcanization. Examples of the vulcanization aid (F) include organic vulcanization accelerators [e.g., sulfenamide accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS) and Nt-butyl-2-benzothiazylsulfenamide (TBBS)], thiuram accelerators such as tetramethylthiuram monosulfide (TMTM) and tetramethylthiuram disulfide (TMTD)], thiazole accelerators such as 2-mercaptobenzothiazole (MBT), zinc salt of MBT, and dibenzothiazyl disulfide (MBTS)], trimethylthiourea (TMU), diethylthiourea (EDE), etc. guanidine-based accelerators such as diphenylguanidine (DPG) and diorthotolylguanidine (DOTG); dithiocarbamate-based accelerators such as sodium dimethyldithiocarbamate; xanthate-based accelerators such as zinc isopropylxanthogenate; aldehyde-amine-based or aldehyde-ammonia-based accelerators such as hexamethylenetetramine, aromatic maleimides (arene bismaleimides such as N,N'-m-phenylenedimaleimide), inorganic auxiliary agents such as zinc oxide (zinc white), magnesium oxide, etc.

[0111] These vulcanization accelerators can be used alone or in combination. Among them, sulfenamide accelerators such as CBS, thiuram accelerators such as TMTD, and inorganic accelerators such as zinc oxide are commonly used.

[0112] The proportion of the vulcanization aid (F) may be, for example, 3 to 20 parts by weight, preferably 4 to 15 parts by weight, and more preferably about 5 to 10 parts by weight, relative to 100 parts by weight of the rubber component (A). The proportion of the organic vulcanization accelerator may be, for example, 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight, and more preferably about 1.5 to 3.5 parts by weight, relative to 100 parts by weight of the rubber component (A). The proportion of the inorganic aid (particularly zinc oxide) may be, for example, 2 to 10 parts by weight, preferably 3 to 8 parts by weight, and more preferably about 4 to 6 parts by weight, relative to 100 parts by weight of the rubber component (A).

[0113] [Other Additives (G)] The vulcanized rubber composition of the present invention may contain conventional additives that are added to vulcanized rubbers depending on the type of rubber component (A). Examples of conventional additives include resin components (such as thermoplastic resins and thermosetting resins), vulcanization retarders, dispersants, antioxidants or antioxidants (such as aromatic amine and benzimidazole antioxidants), colorants (such as dyes and pigments), tackifiers, coupling agents (such as silane coupling agents), stabilizers (such as ultraviolet absorbers, light stabilizers, and heat stabilizers), release agents, lubricants, flame retardants (such as phosphorus-based flame retardants, halogen-based flame retardants, and inorganic flame retardants), flame retardant assistants, antistatic agents, conductive agents, flow control agents, leveling agents, antifoaming agents, surface modifiers, stress reducers, nucleating agents, crystallization accelerators, antibacterial agents, and preservatives.

[0114] These other additives can be used alone or in combination of two or more thereof. The proportion of the other additives may be, for example, about 0.1 to 50 parts by weight, preferably about 0.5 to 30 parts by weight, and more preferably about 1 to 10 parts by weight, per 100 parts by weight of the rubber component (A).

[0115] [Method of manufacturing vulcanized rubber composition] The vulcanized rubber composition of the present invention is obtained through a kneading step in which a rubber component (A) is kneaded with modified cellulose nanofibers (B) to which a fluorene compound (B1) having aryl groups at the 9,9-positions is bonded and / or its raw material, and a vulcanization step in which the obtained kneaded composition is vulcanized to obtain a vulcanized rubber composition.

[0116] In the kneading step, the modified cellulose nanofibers (B) may be the raw materials thereof, the fluorene compound (B1), and unmodified cellulose nanofibers, and by adding these raw materials, the modified cellulose nanofibers (B) are produced in the kneading step and / or vulcanization step.

[0117] In the kneading step, the composition containing the rubber component (A) and the modified cellulose nanofibers (B) can be kneaded by a conventional method, such as a method using a mixing roller, a kneader, a Banbury mixer, an extruder (such as a single-screw or twin-screw extruder), etc. Among these, a pressure kneader is preferred.

[0118] In the kneading step, the rubber component (A) and the modified cellulose nanofibers (B) (or their raw materials) may be added all at once. Alternatively, a dispersion of the modified cellulose nanofibers (B) and / or their raw materials in a processing aid (D) may be pre-dispersed and then kneaded with the rubber component (A). Preparing the dispersion in advance allows the modified cellulose nanofibers (B) to be more uniformly dispersed in the rubber component (A), improving the mechanical properties of the vulcanized rubber. When preparing the dispersion, preferred processing aids (D) include process oils, organic solvents, and plasticizers (including liquid rubbers as plasticizers). When a low-boiling solvent is selected as the processing aid (D), some or all of the solvent volatilizes and does not remain in the vulcanized rubber composition (it does not become a component of the vulcanized rubber composition). The solids concentration in the dispersion is, for example, 0.1 to 50 wt%, preferably 0.5 to 30 wt%, and more preferably 1 to 20 wt%.

[0119] The kneading may be carried out either without heating or with heating. When the kneading is carried out with heating, the kneading temperature is, for example, about 30 to 250°C, preferably about 40 to 225°C, and more preferably about 50 to 200°C.

[0120] In the vulcanization step, the vulcanization temperature can be selected depending on the type of rubber component (A) and is, for example, about 100 to 250°C, preferably about 150 to 200°C, and more preferably about 160 to 190°C.

[0121] The durometer hardness of the obtained vulcanized rubber composition may be 50 or more (particularly 60 or more), but it can also be adjusted to 70 or more, preferably 75 or more (for example, about 75 to 90), by using carbon black as a reinforcing agent.

[0122] In this specification and claims, the durometer hardness can be measured in accordance with JIS K6253 Type A. [Example]

[0123] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Details of the raw materials and measuring instruments used and the evaluation methods are as follows.

[0124] (Raw materials used) BPFG: 9,9-bis(4-glycidyloxyphenyl)fluorene SBR: JSR Corporation "JSR 1502" NBR: JSR Corporation "JSR N230S" EPDM1: JSR Corporation "JSR EP21", Mooney viscosity 26 EPDM2: JSR Corporation "JSR EP27", Mooney viscosity 70 CB N234: "Seast 7HM" manufactured by Tokai Carbon Co., Ltd., average primary particle size 19 nm CB HAF: "Seast 3" manufactured by Tokai Carbon Co., Ltd., average primary particle size 28 nm CB SRF: "Seast S" manufactured by Tokai Carbon Co., Ltd., average primary particle size 66 nm Silica: Tosoh Silica Corporation "Nipsil VN3" Calcium carbonate: "Synthetic calcium carbonate Hakuenka 0" manufactured by Shiraishi Calcium Co., Ltd., average primary particle size 30 nm Process oil: H&R Vivatec 500 (TDAE) Naphthenic oil: Idemitsu Kosan Co., Ltd. "Diana Process NS-100" Paraffin oil: Idemitsu Kosan Co., Ltd. "Diana Process PW-380" Plasticizer DOP: "Bis(2-ethylhexyl) phthalate" manufactured by Mitsubishi Chemical Corporation Zinc oxide No. 1: manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: NOF Corporation "Camellia Stearate Beads" Sulfur: "Powdered sulfur" manufactured by Tsurumi Chemical Co., Ltd. PEG4000: Sanyo Chemical Industries, Ltd. "PEG-4000S" Accelerator CBS: "Noccela CZ-G" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator TT: "Noccela TT-P" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator M: "Noccela MP" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator CZ: "Noccela CZ-G" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator Mix No. 1: "Noccela Mix No. 1" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator DPG: "Noccela D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator DM: "Noccela DM-P" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Accelerator TS: "Noccela TS" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Pulp: "Pure pulp 5mm" manufactured by Sanyo Chemical Co., Ltd.

[0125] (Modification rate of fluorene compounds bound to modified cellulose nanofibers) The modification rate of the fluorene compound (hereinafter referred to as the fluorene modification rate) was determined by Raman analysis using a Raman microscope (XploRA, manufactured by HORIBA JOBIN YVON) and the ratio of the aromatic ring (1604 cm -1 ) and the intra-ring CH of cellulose (1375cm -1 ) and the intensity ratio of the absorption band (I 1604 / I 1375 In this calculation, a diacetyl cellulose (manufactured by Daicel Corporation) film containing a predetermined amount of fluorene compound was prepared by a solution casting method, and the intensity ratio (I 1604 / I 1375 ) A calibration curve was prepared using the following formula. All samples were measured three times, and the average value calculated from the results was used as the fluorene modification rate.

[0126] (Synthesis of modified cellulose nanofibers) 100 g of an aqueous dispersion of cellulose nanofibers (solids concentration 15 wt%) was dispersed in 500 g of N,N-dimethylacetamide (DMAc) and centrifuged. The precipitated solids were then dispersed in 500 g of DMAc and centrifuged again to obtain a mixture of cellulose nanofibers and DMAc (cellulose content approximately 10 wt%). This mixture was transferred to a 1000 mL three-neck flask, and 350 g of DMAc, 15 g of 9,9-bis(4-glycidyloxyphenyl)fluorene (BPFG), and 10 g of diazabicycloundecene (DBU) were added. The mixture was stirred at 120 °C for 3 hours. The resulting mixture was collected by centrifugation and washed with 1200 mL of DMAc three times to obtain modified cellulose nanofibers (B-CNF). The resulting B-CNF had an average fiber diameter of 213 nm and an average fiber length of 30 μm. The modification rate with fluorene compounds was 12 wt%. Figure 1 shows an SEM photograph of the plant-derived cellulose nanofibers used, taken using an SEM (JEOL Ltd., "JSM-6510").

[0127] (Preparation of unmodified cellulose nanofibers) 100 g (solid content 15 g) of an aqueous dispersion of cellulose nanofibers (Daicel FineChem Corporation, "Celish KY110N," cellulose:water (weight ratio) = 15 / 85) was dispersed in 500 g of methanol and filtered by suction. The precipitated solids were then dispersed in 500 g of acetone and filtered by suction again. The residue was dried to obtain dried unmodified cellulose nanofibers (average fiber diameter 10 nm, average fiber length 100 nm).

[0128] (Tensile test) In accordance with JIS K6251, the 25 to 300% tensile stress, tensile strength, and elongation of the vulcanized rubber compositions were measured using a tensile tester ("LTS-1kN" manufactured by Minebea Co., Ltd.) under the following conditions: The tensile stress was measured at elongations selected from 25%, 50%, 100%, 200%, and 300% depending on the example, and the 100% tensile stress was measured in every example, and the relative values ​​to the corresponding comparative example are also shown. Test specimen: No. 8 dumbbell, thickness 2 mm Pulling speed: 5mm / min Initial chuck distance: 30 mm Load cell: 1kN

[0129] (Durometer hardness) The durometer hardness of the vulcanized rubber composition was measured in accordance with JIS K6253 Type A.

[0130] (Mooney viscosity) The Mooney viscosity of the unvulcanized rubber composition was measured in accordance with JIS K6300.

[0131] (density) The density of the vulcanized rubber composition was measured in accordance with JIS K6268.

[0132] Comparative Example 1 (SBR / CB / Blank) The components shown in Table 1 were kneaded at a temperature of 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 180°C to obtain a vulcanized rubber composition.

[0133] [Table 1]

[0134] Example 1 (SBR / CB / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of modified cellulose nanofiber (B-CNF) was added to the unvulcanized rubber composition obtained in Comparative Example 1 in terms of solid content per 100 parts by weight of the composition of Comparative Example 1 to prepare an unvulcanized rubber composition containing modified cellulose nanofiber, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 1.

[0135] Example 2 (SBR / CB / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that the amount of B-CNF added was changed to 5 parts by weight.

[0136] Example 3 (SBR / CB / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that the amount of B-CNF added was changed to 7 parts by weight.

[0137] Table 2 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 1 and Examples 1 to 3.

[0138] [Table 2]

[0139] As is clear from the results in Table 2, the vulcanized rubber compositions of the Examples were improved in 100% tensile stress and hardness compared to the vulcanized rubber composition of Comparative Example 1.

[0140] Comparative Example 2 (3 parts SBR / CB / unmodified cellulose nanofiber) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that the B-CNF was changed to unmodified cellulose nanofibers.

[0141] Comparative Example 3 (5 parts SBR / CB / unmodified cellulose nanofiber) A vulcanized rubber composition was obtained in the same manner as in Example 2, except that the B-CNF was changed to unmodified cellulose nanofibers.

[0142] Comparative Example 4 (SBR / CB / Unmodified Cellulose Nanofiber 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 3, except that the B-CNF was changed to unmodified cellulose nanofibers.

[0143] The evaluation results of the vulcanized rubber compositions obtained in Comparative Examples 2 to 4 are shown in Table 3 together with the evaluation result of Comparative Example 1.

[0144] [Table 3]

[0145] As is clear from the results in Table 3, the addition of unmodified cellulose nanofibers did not improve the physical properties of SBR.

[0146] Comparative Example 5 (SBR / CB / pulp 3 parts) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that B-CNF was replaced with pulp.

[0147] Comparative Example 6 (SBR / CB / pulp 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 2, except that B-CNF was replaced with pulp.

[0148] Comparative Example 7 (SBR / CB / pulp 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 3, except that B-CNF was replaced with pulp.

[0149] The evaluation results of the vulcanized rubber compositions obtained in Comparative Examples 5 to 7 are shown in Table 4 together with the evaluation result of Comparative Example 1.

[0150] [Table 4]

[0151] As is clear from the results in Table 4, the addition of pulp increased hardness, but the increase in 100% tensile stress was small.

[0152] Comparative Example 8 (SBR / Silica / Blank) The components shown in Table 5 were kneaded at 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 180°C to obtain a vulcanized rubber composition.

[0153] [Table 5]

[0154] Example 4 (SBR / silica / B-CNF 3 parts) To the unvulcanized rubber composition obtained in Comparative Example 8, 3 parts by weight of modified cellulose nanofiber (B-CNF) was added in terms of solid content per 100 parts by weight of the composition of Comparative Example 8 using a 6-inch roll to prepare an unvulcanized rubber composition containing modified cellulose nanofiber, and a vulcanized rubber composition was obtained in the same manner as in Comparative Example 8.

[0155] Example 5 (SBR / silica / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 4, except that the amount of B-CNF added was changed to 5 parts by weight.

[0156] Example 6 (SBR / silica / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 4, except that the amount of B-CNF added was changed to 7 parts by weight.

[0157] Table 6 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 8 and Examples 4 to 6.

[0158] [Table 6]

[0159] As is clear from the results in Table 6, the vulcanized rubber compositions of the Examples were improved in tensile stress and hardness by 100 to 300% compared to the vulcanized rubber composition of Comparative Example 8.

[0160] Comparative Example 9 (SBR / Calcium Carbonate / Blank) The components shown in Table 7 were kneaded at 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 180°C to obtain a vulcanized rubber composition.

[0161] [Table 7]

[0162] Example 7 (SBR / Calcium Carbonate / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of modified cellulose nanofiber (B-CNF) was added to the unvulcanized rubber composition obtained in Comparative Example 9 in terms of solid content per 100 parts by weight of the composition of Comparative Example 9 to prepare an unvulcanized rubber composition containing modified cellulose nanofiber, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 9.

[0163] Example 8 (SBR / Calcium Carbonate / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 7, except that the amount of B-CNF added was changed to 5 parts by weight.

[0164] Table 8 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 9 and Examples 7 and 8.

[0165] [Table 8]

[0166] As is clear from the results in Table 8, the vulcanized rubber compositions of Examples were improved in tensile stress and hardness by 100 to 300% compared to the vulcanized rubber composition of Comparative Example 9.

[0167] Comparative Example 10 (EPDM1 / CB / Blank) The components shown in Table 9 were kneaded at 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 170°C to obtain a vulcanized rubber composition.

[0168] [Table 9]

[0169] Example 9 (EPDM1 / CB / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of B-CNF was added to the unvulcanized rubber composition obtained in Comparative Example 10 in terms of solid content per 100 parts by weight of the composition of Comparative Example 10 to prepare an unvulcanized rubber composition containing modified cellulose nanofibers, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 10.

[0170] Example 10 (EPDM1 / CB / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 9, except that the amount of B-CNF added was changed to 5 parts by weight.

[0171] Example 11 (EPDM1 / CB / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 9, except that the amount of B-CNF added was changed to 7 parts by weight.

[0172] Table 10 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 10 and Examples 9 to 11.

[0173] [Table 10]

[0174] As is clear from the results in Table 10, the vulcanized rubber compositions of Examples were improved in 100% tensile stress and hardness compared to the vulcanized rubber composition of Comparative Example 10.

[0175] Comparative Example 11 (EPDM2 / Calcium Carbonate / Blank) The components shown in Table 11 were kneaded at 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 170°C to obtain a vulcanized rubber composition.

[0176] [Table 11]

[0177] Example 12 (EPDM2 / Calcium Carbonate / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of modified cellulose nanofiber (B-CNF) was added to the unvulcanized rubber composition obtained in Comparative Example 11 in terms of solid content per 100 parts by weight of the composition of Comparative Example 11 to prepare an unvulcanized rubber composition containing modified cellulose nanofiber, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 11.

[0178] Example 13 (EPDM2 / Calcium Carbonate / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 12, except that the amount of B-CNF added was changed to 5 parts by weight.

[0179] Example 14 (EPDM2 / Calcium Carbonate / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 12, except that the amount of B-CNF added was changed to 7 parts by weight.

[0180] Table 12 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 11 and Examples 12 to 14.

[0181] [Table 12]

[0182] As is clear from the results in Table 12, the vulcanized rubber compositions of the Examples had 25 to 300% improvements in tensile stress and hardness compared to the vulcanized rubber composition of Comparative Example 11.

[0183] Comparative Example 12 (NBR / CB / Blank) The components shown in Table 13 were kneaded at 150°C using a pressure kneader (manufactured by Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 160°C to obtain a vulcanized rubber composition.

[0184] [Table 13]

[0185] Example 15 (NBR / CB / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of B-CNF was added to the unvulcanized rubber composition obtained in Comparative Example 12 in terms of solid content per 100 parts by weight of the composition of Comparative Example 12 to prepare an unvulcanized rubber composition containing modified cellulose nanofibers, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 12.

[0186] Example 16 (NBR / CB / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 15, except that the amount of B-CNF added was changed to 5 parts by weight.

[0187] Example 17 (NBR / CB / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 15, except that the amount of B-CNF added was changed to 7 parts by weight.

[0188] Table 14 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 12 and Examples 15 to 17.

[0189] [Table 14]

[0190] As is clear from the results in Table 14, the vulcanized rubber compositions of Examples were improved in 100% tensile stress and hardness compared to the vulcanized rubber composition of Comparative Example 12.

[0191] Comparative Example 13 (NBR / Calcium Carbonate / Blank) The components shown in Table 15 were kneaded at 150°C using a pressure kneader (Moriyama Corporation, capacity 10 liters) to prepare an unvulcanized rubber composition. The resulting composition was press-vulcanized at a vulcanization temperature of 160°C to obtain a vulcanized rubber composition.

[0192] [Table 15]

[0193] Example 18 (NBR / Calcium Carbonate / B-CNF 3 parts) Using a 6-inch roll, 3 parts by weight of B-CNF was added to the unvulcanized rubber composition obtained in Comparative Example 13 in terms of solid content per 100 parts by weight of the composition of Comparative Example 13 to prepare an unvulcanized rubber composition containing modified cellulose nanofibers, and a vulcanized rubber composition was obtained in the same manner as Comparative Example 13.

[0194] Example 19 (NBR / Calcium Carbonate / B-CNF 5 parts) A vulcanized rubber composition was obtained in the same manner as in Example 18, except that the amount of B-CNF added was changed to 5 parts by weight.

[0195] Example 20 (NBR / Calcium Carbonate / B-CNF 7 parts) A vulcanized rubber composition was obtained in the same manner as in Example 18, except that the amount of B-CNF added was changed to 7 parts by weight.

[0196] Table 16 shows the evaluation results of the vulcanized rubber compositions obtained in Comparative Example 13 and Examples 18 to 20.

[0197] [Table 16]

[0198] As is clear from the results in Table 16, the vulcanized rubber compositions of Examples had 25 to 300% improvements in tensile stress and hardness compared to the vulcanized rubber composition of Comparative Example 13. [Industrial Applicability]

[0199] The vulcanized rubber composition of the present invention can be used for various industrial components (conveyor belts, rubber cover rolls, gaskets, printing rolls, oil seals, packings, hoses such as oil-resistant hoses, etc.), building components (window frame rubber, vibration-damping materials, carpet bagging materials, etc.), transportation components (automobile components, tires, power transmission belts, etc.), and electrical and electronic equipment components (wire coating, etc.).

Claims

1. A vulcanized rubber composition comprising: a rubber component (A); modified cellulose nanofibers (B) having a fluorene compound (B1) having aryl groups at the 9,9-positions bonded thereto; and at least one vulcanizing agent (E) selected from the group consisting of sulfur-based vulcanizing agents and organic peroxides, the rubber component (A) comprises at least one rubber selected from the group consisting of styrene-butadiene rubber and olefin-based rubber, the proportion of the modified cellulose nanofibers (B) is 0.1 to 10 parts by weight per 100 parts by weight of the rubber component (A), The vulcanizing agent (E) is contained in a proportion of 0.1 to 10 parts by weight per 100 parts by weight of the rubber component (A).

2. 2. The vulcanized rubber composition according to claim 1, wherein the fluorene compound (B1) is a compound represented by the following formula (1): 【Chemistry 1】 (wherein ring Z is an arene ring, R １ and R ２ is a substituent, X １ represents a heteroatom-containing functional group, k represents an integer of 0 to 4, n represents an integer of 1 or more, and p represents an integer of 0 or more.

3. In formula (1), X １ The group - [(OA) ｍ１ -Y １ ] (wherein A is an alkylene group, Y １ 3. The vulcanized rubber composition according to claim 2, wherein m1 is a hydroxyl group or a glycidyloxy group, and m2 is an integer of 0 or more.

4. The vulcanized rubber composition according to any one of claims 1 to 3, wherein the proportion of the fluorene compound (B1) is 0.01 to 33% by weight based on the total amount of the modified cellulose nanofibers (B).

5. The vulcanized rubber composition according to any one of claims 1 to 4, wherein the average fiber diameter of the modified cellulose nanofibers (B) is 4 to 500 nm.

6. The vulcanized rubber composition according to any one of claims 1 to 5, further comprising a reinforcing agent (C) and a processing aid (D).

7. 7. A method for producing a vulcanized rubber composition according to any one of claims 1 to 6, comprising: a kneading step of kneading the rubber component (A), the modified cellulose nanofibers (B) and / or raw materials thereof, and at least one vulcanizing agent (E) selected from the group consisting of sulfur-based vulcanizing agents and organic peroxides; and a vulcanization step of vulcanizing the obtained kneaded composition to obtain a vulcanized rubber composition.

8. The method according to claim 7, wherein the raw materials for the modified cellulose nanofibers (B) are the fluorene compound (B1) and unmodified cellulose nanofibers.

9. The production method according to claim 7 or 8, wherein in the kneading step, the modified cellulose nanofibers (B) and / or a raw material thereof dispersed in advance in the processing aid (D) are kneaded with the rubber component (A).

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