Rubber composition and method for producing the same

Abstract

To provide a rubber composition that is excellent in tensile strength and low heat-generating properties, and a method for producing the same.SOLUTION: A rubber composition contains diene rubber, silica, and a silane coupling agent having a diazo group. The content of the silica is 5-200 pts.mass relative to 100 pts.mass of the diene rubber. The content of the silane coupling agent having the diazo group is 0.2-20 mass% relative to the content of the silica.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition and a method for producing the same. [Background technology]

[0002] Conventionally, a rubber composition containing a diene rubber, silica, and a silane coupling agent having an azo group (azo group-containing silane coupling agent) has been known (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2014-515050 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of the inventors' investigation into the rubber composition described in Patent Document 1, it became clear that its tensile strength and low heat buildup (particularly low heat buildup) do not necessarily satisfy current demands.

[0005] In view of the above circumstances, an object of the present invention is to provide a rubber composition excellent in tensile strength and low heat buildup, and a method for producing the same. [Means for solving the problem]

[0006] As a result of extensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a silane coupling agent having a diazo group, and have arrived at the present invention. That is, the present inventors have found that the above problems can be solved by the following configuration.

[0007] (1) A rubber composition containing a diene rubber, silica, and a silane coupling agent having a diazo group, the content of the silica is 5 to 200 parts by mass per 100 parts by mass of the diene rubber, The rubber composition has a content of the silane coupling agent having a diazo group of 0.2 to 20% by mass relative to the content of the silica. (2) The rubber composition according to (1) above, wherein the diene rubber contains 20% by mass or more of natural rubber. (3) The rubber composition according to (1) or (2) above, wherein the silane coupling agent having a diazo group is the compound (I) described below. (4) Further, a metal catalyst is contained, The rubber composition according to any one of (1) to (3) above, wherein the content of the metal catalyst is 0.01 to 1 mol % based on the content of the silane coupling agent having a diazo group. (5) A method for producing the rubber composition according to (4), A method for producing a rubber composition, comprising mixing the diene rubber and the metal catalyst, and then mixing the silane coupling agent having a diazo group. (6) A method for producing the rubber composition according to (4), A method for producing a rubber composition, comprising mixing the metal catalyst in the form of a solution. [Effects of the Invention]

[0008] As will be described below, the present invention can provide a rubber composition excellent in tensile strength and low heat buildup, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0009] The rubber composition of the present invention and the method for producing the same will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Each component may be used alone or in combination of two or more. When two or more components are used in combination, the content of the components refers to the total content unless otherwise specified.

[0010] The rubber composition of the present invention (hereinafter also referred to as "the composition of the present invention") is The composition contains a diene rubber, silica, and a silane coupling agent having a diazo group, the content of the silica is 5 to 200 parts by mass per 100 parts by mass of the diene rubber, In the rubber composition, the content of the silane coupling agent having a diazo group is 0.2 to 20 mass % relative to the content of the silica.

[0011] The composition of the present invention has such a structure, and it is believed that the above-mentioned effects are achieved. Although the reason for this is not clear, the silane coupling agent having a diazo group (=N2) contained in the composition of the present invention (diazo group-containing silane coupling agent) is thought to have extremely high reactivity with diene rubber (especially natural rubber) due to the diazo group, so when blended into a mixture of diene rubber and silica, the dispersibility of silica in the mixture is extremely high. As a result, it is presumed that the composition of the present invention exhibits excellent tensile strength and low heat buildup. The diazo group is thought to decompose to form a carbene (a highly reactive species) which then reacts with organic materials (e.g., olefins (especially double bonds in rubber)). In particular, electron-deficient carbenes and electron-rich polysubstituted alkenes are compatible and are thought to gain reactivity.

[0012] Each component contained in the composition of the present invention will be described below.

[0013] [1] Diene rubber The diene rubber contained in the composition of the present invention is not particularly limited. The composition of the present invention may contain one diene rubber or two or more diene rubbers.

[0014] [Specific example] Specific examples of the diene rubber include natural rubber (NR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber, isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR), etc. Examples of the aromatic vinyl-conjugated diene copolymer rubber include styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, etc.

[0015] [Molecular weight] The weight average molecular weight (Mw) of the diene rubber is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 100,000 to 5,000,000, more preferably 200,000 to 3,000,000, and even more preferably 300,000 to 2,000,000.

[0016] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​calculated as standard polystyrene obtained by gel permeation chromatography (GPC) measurement.

[0017] [Preferred embodiment] The diene rubber preferably contains natural rubber. When the diene rubber contains natural rubber, the content of natural rubber in the diene rubber is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass, for reasons of better effects of the present invention.

[0018] The content of diene rubber other than natural rubber in the diene rubber is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 10% by mass.

[0019] [2] Silica The silica contained in the composition of the present invention is not particularly limited, and any conventionally known silica compounded in rubber compositions for tires and the like can be used.

[0020] [Specific example] Specific examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Among these, wet silica is preferred because it provides better effects of the present invention. The silica may be used alone or in combination of two or more types. The CTAB (cetyltrimethylammonium bromide) adsorption specific surface area of ​​silica is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 100 to 300 m 2 / g, and 150 to 200m 2 In this specification, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface in accordance with JIS K6217-3:2001 "Part 3: Determination of specific surface area - CTAB adsorption method."

[0021] [Content] In the composition of the present invention, the content of the silica is 5 to 200 parts by mass relative to 100 parts by mass of the diene rubber. In particular, the content of the silica is preferably 10 to 150 parts by mass, more preferably 20 to 100 parts by mass, and even more preferably 30 to 70 parts by mass relative to 100 parts by mass of the diene rubber, for the reason that the effects of the present invention are more excellent.

[0022] [3] Diazo group-containing silane coupling agent The diazo group-containing silane coupling agent contained in the composition of the present invention is not particularly limited as long as it is a silane compound having a diazo group and a hydrolyzable group. The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferred because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, because the effects of the present invention are more excellent. Examples of alkoxy groups having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0023] The diazo group-containing silane coupling agent is preferably a compound having a diazo group and a hydrolyzable silyl group (particularly an alkoxysilyl group), and more preferably compound (I) (specific silane coupling agent) described below, because the effects of the present invention are more excellent.

[0024] [Specific silane coupling agent] The specific silane coupling agent is the following compound (I).

[0025] Compound (I) [ka]

[0026] In compound (I), A represents a divalent aliphatic or aromatic hydrocarbon group having 3 to 26 carbon atoms, which may have a heteroatom or a substituent, and R1, R2, and R3 each independently represent a substituent, provided that at least one of R1, R2, and R3 is an alkoxy group.

[0027] [A] As described above, in compound (I), A represents a divalent aliphatic or aromatic hydrocarbon group having 3 to 26 carbon atoms, which may have a heteroatom or may have a substituent. For the reason that the effects of the present invention are more excellent, A is preferably a group represented by -CH2CH2-R-. Here, R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent. The aliphatic hydrocarbon group may be linear, branched, or cyclic. The above R is preferably a divalent aliphatic hydrocarbon group (particularly an alkylene group) having 1 to 5 carbon atoms, for reasons such as better effects of the present invention.

[0028] [R1, R2 and R3] As described above, in Compound (I), R1, R2, and R3 each independently represent a substituent, provided that at least one of R1, R2, and R3 is an alkoxy group.

[0029] The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably 1 to 5, as this provides better effects of the present invention.

[0030] Specific examples of the above substituents other than alkoxy groups include aliphatic hydrocarbon groups, aromatic hydrocarbon groups, and groups combining these groups. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups (particularly having 1 to 30 carbon atoms), linear or branched alkenyl groups (particularly having 2 to 30 carbon atoms), and linear or branched alkynyl groups (particularly having 2 to 30 carbon atoms). Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms, such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. When the above-mentioned substituent is other than an alkoxy group, it is preferably an aliphatic hydrocarbon group, more preferably an alkyl group (particularly having 1 to 5 carbon atoms), for reasons such as better effects of the present invention.

[0031] In compound (I), it is preferred that R1, R2 and R3 are all alkoxy groups, as this will result in better effects of the present invention.

[0032] [Method of manufacturing specific silane coupling agent] The method for producing the specific silane coupling agent is not particularly limited, but because the use of the obtained specific silane coupling agent further improves the tensile strength and low heat buildup of the composition of the present invention, the below-described Method 1 of the present invention and the below-described Method 2 of the present invention are preferred, and the below-described Method 1 of the present invention is more preferred. Hereinafter, "the use of the obtained specific silane coupling agent further improves the tensile strength and low heat buildup of the composition of the present invention" will also be simply referred to as "the effects, etc. of the present invention are better."

[0033] [Method 1 of the present invention] Method 1 of the present invention is a vinyl group introduction step of reacting a compound (III) described below with a compound represented by CH═CH—R—OH (wherein R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent) (hereinafter also referred to as a “specific alcohol”) to synthesize a compound (IV) described below; a hydrosilylation step of reacting the compound (IV) with a compound (VI) described below to synthesize a compound (VII) described below; The method for producing a silane coupling agent includes a diazotization step in which a silane coupling agent (specific silane coupling agent), which is a compound (I) described below, is synthesized by reacting a compound (II) described below with the compound (VII) described above.

[0034] Each step will be described below.

[0035] [Vinyl group introduction process] The vinyl group introduction step is a step of synthesizing the following compound (IV) by reacting the following compound (III) with a specific alcohol.

[0036] <Compound (III)>

[0037] Compound (III) [ka]

[0038] In compound (III), X1 and X2 each independently represent a halogen atom.

[0039] As described above, in compound (III), X1 and X2 each independently represent a halogen atom. The halogen atom is not particularly limited, but is preferably a bromine atom, because this increases the yield of the specific silane coupling agent and provides a more effective effect of improving the dispersibility of silica in the resulting specific silane coupling agent.

[0040] <Specific alcohol> The specific alcohol is a compound represented by CH2=CH-R-OH (wherein R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent). The aliphatic hydrocarbon group may be linear, branched, or cyclic. The above R is preferably a divalent aliphatic hydrocarbon group (particularly an alkylene group) having 1 to 5 carbon atoms, for reasons such as better effects of the present invention.

[0041] <Compound (IV)>

[0042] Compound (IV) [ka]

[0043] In compound (IV), R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent, and X represents a halogen atom.

[0044] Specific examples and preferred embodiments of R are the same as those of the specific alcohols described above. Specific examples and preferred embodiments of X are the same as those of X in the compound (III) described above.

[0045] <Preferred embodiment> The vinyl group introduction step is preferably carried out in the following manner, because it is more effective in the present invention. The process is preferably a step of synthesizing the compound (IV) by reacting the compound (III) with the specific alcohol in the presence of sodium hydrogen carbonate and acetonitrile.

[0046] [Hydrosilylation step] The hydrosilylation step is a step of synthesizing the following compound (VII) by reacting the compound (IV) obtained in the vinyl group introduction step described above with the following compound (VI).

[0047] <Compound (VI)>

[0048] Compound (VI) [ka]

[0049] In compound (VI), R1, R2, and R3 each independently represent a substituent, provided that at least one of R1, R2, and R3 is an alkoxy group.

[0050] The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably 1 to 5, as this provides better effects of the present invention.

[0051] Specific examples of the above substituents other than alkoxy groups include aliphatic hydrocarbon groups, aromatic hydrocarbon groups, and groups combining these groups. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups (particularly having 1 to 30 carbon atoms), linear or branched alkenyl groups (particularly having 2 to 30 carbon atoms), and linear or branched alkynyl groups (particularly having 2 to 30 carbon atoms). Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms, such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. When the above-mentioned substituent is other than an alkoxy group, it is preferably an aliphatic hydrocarbon group, more preferably an alkyl group (particularly having 1 to 5 carbon atoms), for reasons such as better effects of the present invention.

[0052] In compound (VI), it is preferred that R1, R2 and R3 are all alkoxy groups, as this will result in better effects of the present invention.

[0053] <Compound (VII)>

[0054] Compound (VII) [ka]

[0055] In compound (VII), A represents a divalent aliphatic or aromatic hydrocarbon group having 3 to 26 carbon atoms, which may have a heteroatom or a substituent; R1, R2, and R3 are defined as R1, R2, and R3 in compound (VI) above; and X is defined as X in compound (IV) above.

[0056] As described above, in compound (VII), A represents a divalent aliphatic or aromatic hydrocarbon group having 3 to 26 carbon atoms, which may have a heteroatom or a substituent. The above A is preferably a group represented by -CH2CH2-R- because it provides better effects of the present invention, etc. Here, the definition, specific and preferred embodiments of R are the same as those of R in the specific alcohol described above.

[0057] As described above, in compound (VII), the definitions of R1, R2, and R3 are the same as those of R1, R2, and R3 in compound (VI). Specific examples and preferred embodiments of R1, R2, and R3 are also the same as those of R1, R2, and R3 in compound (VI).

[0058] As described above, in compound (VII), the definition of X is the same as that of X in compound (IV) described above. Specific examples and preferred embodiments of X are also the same as those of X in compound (IV) described above.

[0059] <Preferred embodiment> The hydrosilylation step is preferably carried out in the following manner, because it is more effective in the present invention. It is preferable that the compound (VII) is synthesized by subjecting the compound (IV) obtained in the vinyl group introduction step and the compound (VI) to a hydrosilylation reaction at room temperature in the presence of an iridium catalyst and dichloromethane.

[0060] Examples of the iridium catalyst include iridium salts, iridium complexes, etc. Specific examples of the iridium salt include iridium trichloride, iridium tetrachloride, chloroiridic acid, sodium chloroiridate, and potassium chloroiridate. Specific examples of iridium complexes include chloro(1,5-cyclooctadiene)iridium(I) dimer, bromo(1,5-cyclooctadiene)iridium(I) dimer, iodo(1,5-cyclooctadiene)iridium(I) dimer, chloro(2,5-norbornadiene)iridium(I) dimer, bromo(2,5-norbornadiene)iridium(I) dimer, iodo(2,5-norbornadiene)iridium(I) dimer, 1,5-cyclooctadiene(acetylacetonato)iridium(I), chlorobis(cyclooctene)iridium(I) dimer, and chlorocarbonylbis(triphenylphosphine)iridium(I). In particular, it is preferable to use chloro(1,5-cyclooctadiene)iridium(I) dimer because it provides superior effects of the present invention.

[0061] [Diazotization step] The diazotization step is a step of synthesizing a silane coupling agent (specific silane coupling agent), which is the following compound (I), by reacting the following compound (II) with the compound (VII) obtained in the above-mentioned hydrosilylation step.

[0062] <Compound (II)>

[0063] Compound (II) [ka]

[0064] In compound (II), Ts represents a tosyl group.

[0065] The method for synthesizing compound (II) is not particularly limited, but a method in which p-toluenesulfonyl hydrazide and paratoluenesulfonyl chloride are reacted in the presence of pyridine and dichloromethane is preferred because it provides better effects of the present invention.

[0066] <Compound (I)>

[0067] Compound (I) [ka]

[0068] In compound (I), the definition of A is the same as that of A in compound (VII) described above, and the definitions of R1, R2, and R3 are the same as that of R1, R2, and R3 in compound (VI) described above.

[0069] As described above, in compound (I), the definition of A is the same as that of A in compound (VII) described above. Specific examples and preferred embodiments of A are also the same as those of A in compound (VII) described above.

[0070] As described above, in compound (I), the definitions of R1, R2, and R3 are the same as those of R1, R2, and R3 in compound (VI). Specific examples and preferred embodiments of R1, R2, and R3 are also the same as those of R1, R2, and R3 in compound (VI).

[0071] <Preferred embodiment> The diazotization step is preferably carried out in the following manner, because it is more effective in the present invention. It is preferable that the compound (II) and the compound (VII) obtained in the hydrosilylation step are subjected to a diazotization reaction in the presence of tetramethylguanidine and tetrahydrofuran to synthesize the silane coupling agent, which is the compound (I).

[0072] [Method 2 of the present invention] Method 2 of the present invention is a vinyl group introduction step of reacting a compound (III) described below with a compound represented by CH═CH—R—OH (wherein R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent) (specific alcohol) to synthesize a compound (IV) described below; a diazotization step in which a compound (II) described below is reacted with the compound (IV) to synthesize a compound (V) described below; The method for producing a silane coupling agent includes a hydrosilylation step of reacting the compound (V) with a compound (VI) described later to synthesize a silane coupling agent (specific silane coupling agent), which is a compound (I) described later.

[0073] Each step will be described below.

[0074] [Vinyl group introduction process] The vinyl group introduction step is the same as the vinyl group introduction step in the above-mentioned Method 1 of the present invention.

[0075] [Diazotization step] The diazotization step is a step of synthesizing the following compound (V) by reacting the following compound (II) with the compound (IV) obtained in the vinyl group introduction step described above.

[0076] <Compound (II)> The compound (II) is the same as the compound (II) used in the diazotization step of the above-mentioned Method 1 of the present invention.

[0077] <Compound (V)>

[0078] Compound (V) [ka]

[0079] In compound (V), R represents a divalent aliphatic or aromatic hydrocarbon group having 1 to 24 carbon atoms, which may have a heteroatom or a substituent.

[0080] Specific examples and preferred embodiments of R are the same as those of the specific alcohols described above.

[0081] <Preferred embodiment> The diazotization step is preferably a step of synthesizing the above-mentioned compound (V) by subjecting the above-mentioned compound (II) and the compound (IV) obtained in the above-mentioned vinyl group introduction step to a diazotization reaction in the presence of diazabicycloundecene and tetrahydrofuran, because this step provides better effects of the present invention.

[0082] [Hydrosilylation step] The hydrosilylation step is a step of synthesizing a silane coupling agent (specific silane coupling agent), which is the following compound (I), by reacting the compound (V) obtained in the above-mentioned diazotization step with the following compound (VI):

[0083] <Compound (VI)> The compound (VI) is the same as the compound (VI) used in the hydrosilylation step of the above-described Method 1 of the present invention.

[0084] <Compound (I)> The above compound (I) (specific silane coupling agent) is the same as the compound (I) (specific silane coupling agent) synthesized in the diazotization step of the above-described method 1 of the present invention.

[0085] <Preferred embodiment> The hydrosilylation step is preferably a step of synthesizing the above-mentioned compound (I) (specific silane coupling agent) by subjecting the compound (V) obtained in the above-mentioned diazotization step to a hydrosilylation reaction with the above-mentioned compound (VI) in the presence of a Karstedt catalyst, because this step provides better effects of the present invention.

[0086] [Content] In the composition of the present invention, the content of the diazo group-containing silane coupling agent is 0.2 to 20 mass % relative to the content of the silica, and particularly, the content of the diazo group-containing silane coupling agent is preferably 1 to 15 mass %, more preferably 4 to 12 mass %, relative to the content of the silica.

[0087] Furthermore, when the diene rubber contains natural rubber, the content of the diazo group-containing silane coupling agent in the composition of the present invention is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, even more preferably 3 to 12 parts by mass, and particularly preferably 4 to 8 parts by mass, per 100 parts by mass of the natural rubber, for reasons of better effects of the present invention.

[0088] In the composition of the present invention, the diazo group-containing silane coupling agent may be reacted with the diene rubber. In this case, the content of the diazo group-containing silane coupling agent refers to the content at the time of blending.

[0089] [4] Optional component The composition of the present invention may further contain other components (optional components) as needed, provided that the effects and purposes of the composition are not impaired. Examples of the optional components include various additives commonly used in rubber compositions, such as carbon black, silane coupling agents other than the above-mentioned diazo group-containing silane coupling agents, terpene resins (e.g., aromatic modified terpene resins), thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, oils, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), and vulcanization accelerators.

[0090] [Metal catalyst] The composition of the present invention preferably further contains a metal catalyst, because the effects of the present invention are more excellent. When the composition of the present invention contains a metal catalyst, it is believed that the reaction of the diazo group with the diene rubber (particularly natural rubber) proceeds more easily.

[0091] The metal catalyst is not particularly limited, and examples thereof include metal particles made of a metal element, metal compounds containing a metal element (preferably salts and metal complexes), etc. Among these, metal compounds are preferred, and metal salts or metal complexes are more preferred, because they provide better effects of the present invention. The metal element is not particularly limited, but is preferably a transition metal element, more preferably an element in Groups 8 to 11 of the periodic table, and even more preferably rhodium, for reasons of better effects of the present invention. The metal catalyst is preferably a metal compound containing rhodium, more preferably a rhodium salt or a rhodium complex, and even more preferably rhodium acetate, because this provides a better effect of the present invention.

[0092] [Content] In the composition of the present invention, the content of the metal catalyst is preferably 0.01 to 10 mol %, more preferably 0.02 to 5 mol %, even more preferably 0.05 to 2 mol %, and particularly preferably 0.05 to 0.5 mol %, relative to the content of the diazo group-containing silane coupling agent, because this provides better effects of the present invention.

[0093] [5] Method for producing the composition of the present invention The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include a method of kneading the above-mentioned components using a known method or apparatus (e.g., a Banbury mixer, a kneader, a roll, etc.) When the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than the sulfur and the vulcanization accelerator at a high temperature, cool the mixture, and then mix the sulfur or the vulcanization accelerator. The composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0094] [When a metal catalyst is further contained] When the composition of the present invention further contains a metal catalyst, it is preferable to mix the diene rubber and the metal catalyst and then mix the diazo group-containing silane coupling agent, because this will result in a more homogeneous composition.

[0095] Furthermore, when the composition of the present invention further contains a metal catalyst, it is preferable to mix the metal catalyst as a solution, because this will result in a more homogeneous composition, and the effects of the present invention will be more excellent in the resulting composition of the present invention. The solvent for the metal catalyst solution is not particularly limited, but is preferably an organic solvent (particularly acetonitrile) because this will provide a more excellent effect of the present invention for the resulting composition of the present invention.

[0096] [6]Applications The composition of the present invention is suitable for use as a rubber material. For example, it is suitable for use in tires (particularly pneumatic tires), conveyor belts, hoses, vibration-proof materials, rubber rolls, outer covers for railway vehicles, etc. Among these, it is particularly suitable for use in tires (particularly treads). [Example]

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0098] [Synthesis of diazo group-containing silane coupling agent 1]

[0099] <Synthesis of Compound (II)> A 300 mL three-neck flask equipped with a thermometer was charged with a suspension of p-Toluenesulfonyl Hydrazide (Tokyo Chemical Industry Co., Ltd., 18.6 g) and p-Toluenesulfonyl Chloride (Tokyo Chemical Industry Co., Ltd., 28.6 g) in CHCl and cooled in an ice bath. A 1:1 mixture of pyridine and CHCl (25 mL) was added dropwise over approximately 10 minutes using a dropping funnel, maintaining the internal temperature below 20°C. The reaction mixture was stirred at room temperature for 3 hours. EtO (diethyl ether) (60 mL) was added, and the mixture was poured into a 1 L beaker. 60 mL of purified water and 60 mL of EtO were added, in that order, and the mixture was stirred at room temperature for 10 minutes. The white precipitate was collected by filtration, transferred to a 500 mL recovery flask, and dried under reduced pressure. MeOH (methanol) (260 mL) was added to the crude product, and the mixture was stirred for 3 hours under gentle reflux at a bath temperature of 80° C. After cooling to room temperature, the white precipitate was collected by filtration and washed with MeOH (90 mL) and EtO (90 mL). The resulting solid was dried under reduced pressure to give 26.9 g of a white solid. 1 H and 13 From the C NMR spectrum, it was confirmed that the obtained white solid was Ts-NHNH-Ts (Ts: tosyl group) (corresponding to the above-mentioned compound (II)). The yield was 79%.

[0100] <Vinyl group introduction process> A 1-L three-neck flask equipped with a thermometer was charged with sodium bicarbonate (NaHCO3) (Fujifilm Wako Pure Chemical Industries, Ltd., 39.6 g), 3-butene-1-ol (corresponding to the specific alcohol described above, where R is -CH2CH2-) (Tokyo Chemical Industry Co., Ltd., 13.5 mL), and acetonitrile (400 mL) and cooled in an ice bath. Bromoacetyl bromide (corresponding to compound (III) described above, where X1 and X2 are bromine atoms) (Tokyo Chemical Industry Co., Ltd., 20 mL) was added dropwise to this mixture using a dropping funnel over approximately 1 hour while maintaining the internal temperature at 4-5°C. After stirring at the same temperature for an additional 30 minutes, the disappearance of 3-butene-1-ol was confirmed by TLC (thin-layer chromatography). Pure water (500 mL) was placed in a 3 L beaker, and the resulting reaction solution was poured into it while stirring. The reaction vessel was washed with pure water and then with a small amount of acetonitrile, and the washed solution was added to the mixture. The mixture was stirred at room temperature for approximately 5 minutes, and then extracted with CHCl (600 mL). The mixture was placed in a 2 L separatory funnel and extracted with CHCl (600 mL), and the CHCl layer was washed with brine. The CHCl layer was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The residual oil was dried under reduced pressure to obtain 28.6 g of a colorless oily product. of reaction products 1 H and 13 From the C NMR spectrum, the oily product was confirmed to be the above-mentioned compound (IV) (wherein R is -CHCH- and X is a bromine atom). The yield was 94%.

[0101] <Hydrosilylation step> In a 500 mL three-neck flask equipped with a thermometer, add [IrCl(CH 12 )]2 (Fujifilm Wako Pure Chemical Industries, Ltd., 0.955 g) was added to the reaction vessel, which was then evacuated and purged with nitrogen. Anhydrous CHCl (148 mL) was added, and the reaction vessel was cooled in an ice bath. While maintaining the internal temperature at 3-4°C, diethoxymethylsilane (corresponding to the above-mentioned compound (VI), where two of R1, R2, and R3 are ethoxy groups and one is a methyl group) (Tokyo Chemical Industry Co., Ltd., 32 mL) was added dropwise over approximately 30 minutes using a dropping funnel. Subsequently, a CHCl solution (15 mL) of compound (IV) (28.6 g), synthesized as described above, was added dropwise using a dropping funnel over approximately 1 hour. The mixture was stirred at the same temperature for approximately 30 minutes, and the disappearance of compound (IV) was confirmed by TLC. SiO2 (114 g) was suspended in 500 mL of a 20 / 80 AcOEt (ethyl acetate) / n-hexane mixture in a 3 L beaker. The suspension was cooled in an ice bath with stirring, and the reaction solution was slowly and gently poured into the suspension. A 15 cm Kiriyama funnel was attached to a 3 L suction bottle. Celite® was placed on top of the funnel's filter paper, and the Celite was compressed under suction to form an approximately 1 cm thick pad. The quenched reaction mixture was filtered through the Celite pad to separate SiO2 and insoluble materials. The filtrate was washed with 500 mL of a 20 / 80 AcOEt / n-hexane mixture, followed by 600 mL of a 30 / 70 AcOEt / n-hexane mixture. The filtrate was concentrated under reduced pressure to yield approximately 46 g of a crude product as a pale brown oil. The crude product was purified by column chromatography to yield 42.46 g of a pale yellow oil.

[0102] (Column purification conditions) ·Yamazen Smart Flash EPLC AI 580S ·Column Size 4L(SiO2200g), injection column 2L ·AcOEt / n-hexane=0 / 100 → 9 / 91 UV 254nm

[0103] 1 H, 13 C and 29 From the Si NMR spectrum, the oily substance was confirmed to be the above-mentioned compound (VII) (wherein A is -CH2CH2CH2CH2-, two of R1, R2, and R3 are ethoxy groups and one is a methyl group, and X is a bromine atom). The yield was 80%.

[0104] <Diazotization process> Compound (VII), synthesized as described above, was placed in a 100 mL three-neck flask equipped with a thermometer, vacuumed, and purged with nitrogen. It was dissolved in 12 mL of anhydrous THF (tetrahydrofuran), and Ts-NHNH-Ts (1.59 g), synthesized as described above, was added using a powder funnel. The flask was cooled to -10 °C, and a solution of tetramethylguanidine (Tokyo Chemical Industry Co., Ltd., 32 mL) in anhydrous THF (1.3 mL) was added dropwise over approximately 20 min using a dropping funnel, maintaining the internal temperature at -5 to -3 °C. At the start of the addition, Ts-NHNH-Ts was not completely dissolved and remained as a suspension. As the addition continued, it dissolved completely, forming a homogeneous solution, followed by the gradual formation of a white precipitate. The mixture was stirred for an additional 20 min while cooled to the same temperature, and TLC confirmed that the starting material had almost completely disappeared. The reaction mixture was removed from the cooling device and stirred for approximately 1 h while allowing it to warm naturally to room temperature. The reaction mixture was a yellow solution containing a white precipitate. After confirming the disappearance of the compound (VII) product by TLC, EtO (50 mL) was added to the reaction solution. The reaction mixture was filtered through a Kiriyama funnel lined with SiO (5 g). The filtrate was washed four times with 15 mL of EtO. The filtrate and washings were combined and concentrated under reduced pressure, and the residue was purified using a SiO column. 0.674 g of a yellow oil was obtained.

[0105] (Column purification conditions) ·Yamazen Smart Flash EPLC AI 580S ·Column Size M(SiO216g), injection column S ·AcOEt / n-hexane =0 / 100 → 17 / 83 UV 254nm

[0106] 1 H, 13 C and 29From the Si NMR spectrum, the oily substance obtained was confirmed to be the above-mentioned compound (I) (wherein A is -CH2CH2CH2CH2-, and two of R1, R2, and R3 are ethoxy groups and one is a methyl group) (specific silane coupling agent). The yield was 52%. The obtained compound (I) is also referred to as diazo group-containing silane coupling agent 1.

[0107] [Synthesis of diazo group-containing silane coupling agent 2] An oily product was obtained according to the same procedure as for the above-mentioned diazo group-containing silane coupling agent 1, except that triethoxysilane (corresponding to the above-mentioned compound (VI), where R1, R2, and R3 are ethoxy groups) was used instead of diethoxymethylsilane in the hydrosilylation step.

[0108] 1 H, 13 C and 29 From the Si NMR spectrum, the oily substance obtained was confirmed to be the above-mentioned compound (I) (where A is -CH2CH2CH2CH2-, and R1, R2, and R3 are ethoxy groups) (specific silane coupling agent). The yield was 30%. The obtained compound (I) is also referred to as diazo group-containing silane coupling agent 2.

[0109] [Preparation of Rubber Composition] The components shown in Tables 1 and 2 below were compounded in the proportions (parts by mass) shown in the tables. Specifically, the components shown in Tables 1 and 2 below, excluding sulfur and vulcanization accelerator, were first heated to around 140°C using a 1.7-liter internal Banbury mixer, mixed for 5 minutes, then discharged and cooled to room temperature to obtain a masterbatch. Furthermore, sulfur and vulcanization accelerator were mixed into the obtained masterbatch using the Banbury mixer to obtain each rubber composition. In Example 5, the metal catalyst and the diazo group-containing silane coupling agent were mixed simultaneously, and in Example 6, the diene rubber and the metal catalyst were mixed together, and then the diazo group-containing silane coupling agent was mixed.

[0110] 〔evaluation〕 The obtained rubber compositions were evaluated as follows: The amount of bound rubber was evaluated for some of the rubber compositions.

[0111] <Tensile strength> Each of the resulting rubber compositions (unvulcanized) was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 150°C for 30 minutes to produce a vulcanized rubber sheet. Next, JIS No. 3 dumbbell-shaped test specimens (thickness: 2 mm) were punched out of the resulting vulcanized rubber sheets in accordance with JIS K6251:2010, and the tensile strength (strength at break) was evaluated at a temperature of 20°C and a pulling speed of 500 mm / min. The results are shown in Tables 1 and 2. The results are expressed as an index, with the conventional example being 100. It can be said that the larger the index, the better the tensile strength. In practice, an index of 104 or more is preferable.

[0112] <tanδ(60℃)> For the vulcanized rubber sheets obtained as described above, tan δ(60°C) was measured in accordance with JIS K6394:2007 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) under conditions of an elongation deformation strain rate of 10%±2%, a frequency of 20 Hz, and a temperature of 60°C. The results are shown in Tables 1 and 2. The results are expressed as an index with the conventional example being 100. It can be said that the smaller the index, the better the low heat buildup property.

[0113] <Amount of bound rubber> 0.3 g of the obtained composition was placed in a wire mesh basket and immersed in 300 mL of toluene at room temperature for 48 hours, then removed and dried. The mass of the sample was measured and the amount of bound rubber was calculated using the following formula. Bound rubber mass = [(mass of sample after toluene immersion and drying) - (mass of silica)] / (mass of rubber component) The results are shown in Table 2. The results are expressed as an index with the conventional example being 100. The larger the amount of bound rubber, the more bound rubber (rubber that has reacted with silica) there is, which means that the dispersibility of silica in the rubber composition is higher.

[0114] [Table 1]

[0115] [Table 2]

[0116] Details of each component in Tables 1 and 2 are as follows. NR: Natural rubber ·Silica: ZEOSIL 1165MP (CTAB adsorption specific surface area: 159m 2 / g, manufactured by Rhodia) Zinc oxide: Zinc oxide Vulcanization accelerator: Vulcanization accelerator Sulfur: Sulfur TESPT:Si69 (bis(3-triethoxysilylpropyl)tetrasulfide, manufactured by Evonik Degussa) Azo group-containing silane coupling agent: azosilane of formula (Ia) described in paragraphs

[0068] to

[0069] of JP-A No. 2014-515050 Diazo group-containing silane coupling agents 1 and 2: Diazo group-containing silane coupling agents 1 and 2 synthesized as described above Metal catalyst: Rhodium(II) acetate (dimer) (Tokyo Chemical Industry Co., Ltd.)

[0117] The reason why the amount of sulfur in Comparative Examples 1 and 2 is smaller than that in the other examples is to suppress an increase in hardness of the vulcanized rubber due to the release of sulfur atoms in TESPT. In addition, in Table 2, examples marked with "A" in the metal catalyst addition method column are examples in which the metal catalyst and diazo group-containing silane coupling agent 2 were mixed simultaneously, and examples marked with "B" in the metal catalyst addition method column are examples in which the diene rubber and metal catalyst were mixed together and then the diazo group-containing silane coupling agent 2 was mixed.

[0118] As can be seen from Table 1, a comparison between Comparative Example 1, Comparative Example 3, and Example 1 (comparison between the embodiments in which the silane coupling agent was 5 parts by mass) shows that Example 1, which contained a diazo group-containing silane coupling agent, exhibited superior tensile strength and low heat buildup compared to Comparative Example 1 and Comparative Example 3, which contained a silane coupling agent other than a diazo group-containing silane coupling agent. Similarly, a comparison between Comparative Example 2 and Example 3 (comparison between the embodiments in which the silane coupling agent was 10 parts by mass) shows that Example 3, which contained a diazo group-containing silane coupling agent, exhibited superior tensile strength and low heat buildup compared to Comparative Example 2, which contained a silane coupling agent other than a diazo group-containing silane coupling agent. Similarly, a comparison between Comparative Example 4 and Example 2 (comparison between the embodiments in which the silane coupling agent was 1 part by mass) shows that Example 2, which contained a diazo group-containing silane coupling agent, exhibited superior tensile strength and low heat buildup compared to Comparative Example 4, which contained a silane coupling agent other than a diazo group-containing silane coupling agent. Comparing Examples 1 to 3, Example 1, in which the content of the diazo group-containing silane coupling agent was 5 to 15 mass % relative to the content of silica, showed superior tensile strength and low heat buildup.

[0119] Furthermore, as can be seen from Table 2, Examples 4 to 6, which contained a diazo group-containing silane coupling agent, exhibited excellent low heat buildup properties compared to Comparative Examples 1 and 3, which contained a silane coupling agent other than a diazo group-containing silane coupling agent. Among these, Examples 5 and 6, which further contained a metal catalyst, exhibited even better tensile strength and low heat buildup properties. Among these, Example 6, in which a diene rubber and a metal catalyst were mixed together and then a diazo group-containing silane coupling agent was mixed, exhibited even more excellent low heat buildup properties.

Claims

1. The composition contains a diene rubber, silica, and a silane coupling agent having a diazo group, The silane coupling agent having a diazo group is the following compound (I): the content of the silica is 5 to 200 parts by mass per 100 parts by mass of the diene rubber, The rubber composition has a content of the silane coupling agent having a diazo group of 0.2 to 20 mass % relative to the content of the silica. 【Chemical 1】 Compound (I) In compound (I), A represents a divalent aliphatic or aromatic hydrocarbon group having 3 to 26 carbon atoms, which may have a heteroatom or a substituent, and R 1 , R 2 , and R 3 each independently represent a substituent, provided that at least one of R 1 , R 2 , and R 3 is an alkoxy group.

2. The rubber composition according to claim 1, wherein the diene rubber has a natural rubber content of 20% by mass or more.

3. Further, it contains a metal catalyst, 3. The rubber composition according to claim 1, wherein the content of the metal catalyst is 0.01 to 1 mol % based on the content of the silane coupling agent having a diazo group.

4. A method for producing the rubber composition according to claim 3, A method for producing a rubber composition, comprising mixing the diene rubber and the metal catalyst, and then mixing the silane coupling agent having a diazo group therein.

5. A method for producing the rubber composition according to claim 3, A method for producing a rubber composition, comprising mixing the metal catalyst in the form of a solution.

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