Method for measuring the reaction amount of silane coupling agents

Abstract

To provide a method for measuring a bonding amount between a silane coupling agent and a rubber component in a rubber composition.SOLUTION: A method for measuring a reaction amount between a silane coupling agent and a rubber component in a rubber composition includes: a step of kneading the rubber component, the silane coupling agent, a vulcanizer, and a vulcanization accelerator without the addition of silica to obtain an unvulcanized or vulcanized rubber composition; an extraction step of subjecting the obtained rubber composition to extraction treatment by using a solvent immiscible with the rubber component, to extract the unreacted silane coupling agent contained in the rubber composition; and a quantification step of measuring a solid13C-NMR of the rubber composition after extraction, and quantifying the reaction amount based on a ratio of a peak area of carbon peaks originating from specific carbon atoms of the rubber component in the obtained solid13C-NMR spectrum to a peak area of carbon peaks originating from specific carbon atoms of the silane coupling agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the reaction amount between a silane coupling agent and a rubber component in a rubber composition. [Background technology]

[0002] Silane coupling agents, when added to and mixed with silica and rubber components, react with the silanol groups on the silica surface and with the polymer in the rubber component, thereby linking the two and improving the dispersibility of silica. To improve the dispersibility of silica, it is necessary to increase the amount of silane coupling agent that reacts with the silica.

[0003] Patent Document 1 describes a method for measuring the reaction amount of a silane coupling agent in a silica-based formulation. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5027175 [Overview of the project] [Problems that the invention aims to solve]

[0005] As described above, in silica-containing rubber compositions, it is considered important to analyze and evaluate in detail the bonding between silica, silane coupling agent, and polymer via the silane coupling agent. However, the method described in Patent Document 1 can only measure the reaction amount between silica and the silane coupling agent, and cannot evaluate the reaction amount between the silane coupling agent and the polymer.

[0006] On the other hand, in the manufacturing process of rubber compositions for tires, it is known that there is a correlation between the number of kneading cycles and the low fuel consumption performance due to silica dispersion. However, in order to determine the effectiveness of the process, it was necessary to vulcanize the rubber composition and measure its viscoelasticity.

[0007] If a method can be developed to predict the dispersibility and other physical properties of silica at the stage of the unvulcanized rubber composition, it could be a useful method for finding optimal manufacturing conditions that fully bring out the performance of silica.

[0008] The present invention aims to provide a method for measuring the reaction amount between a silane coupling agent and a rubber component in a rubber composition. [Means for solving the problem]

[0009] After thorough investigation, it was determined that an unvulcanized or vulcanized rubber composition could be prepared by kneading rubber components, a silane coupling agent, a vulcanizing agent, and a vulcanization accelerator without adding silica, and then extracting the unreacted silane coupling agent from the rubber composition. 13 It was found that the above problem could be solved by measuring C-NMR.

[0010] In other words, the present invention is [1] A method for measuring the reaction amount between a silane coupling agent and a rubber component in a rubber composition, comprising: a step of kneading a rubber component, a silane coupling agent, a vulcanizing agent, and a vulcanization accelerator without adding silica to obtain an unvulcanized or vulcanized rubber composition; an extraction step of extracting the unreacted silane coupling agent contained in the rubber composition by performing an extraction treatment on the obtained rubber composition using a solvent in which the rubber component does not dissolve; and the solid rubber composition after extraction. 13 The obtained solid was measured by measuring C-NMR. 13 A measurement method comprising a quantitative step of quantifying the reaction amount based on the ratio of the peak area of ​​the carbon peak originating from a specific carbon atom of the rubber component in the 1C-NMR spectrum to the peak area of ​​the carbon peak originating from a specific carbon atom of the silane coupling agent. [2] The measurement method described in [1] above, wherein a specific carbon atom of the rubber component is a carbon atom that forms a double bond. [3] The measurement method according to [1] or [2] above, wherein a specific carbon atom of the silane coupling agent is a carbon atom other than the carbon atoms constituting the alkoxysilyl moiety. 〔4〕The specific carbon atom of the silane coupling agent is any carbon atom intervening between a silicon atom and a sulfur atom, the measuring method according to any one of 〔1〕 to 〔3〕 above, 〔5〕Solid 13 The measurement conditions for solid C-NMR are a measurement mode of DD / MAS, a waiting time of 1 to 30 seconds, an integration number of 1000 times or more, and a MAS rotation frequency of 4 kHz or more at a resonance frequency of 400 MHz, the measuring method according to any one of 〔1〕 to 〔4〕 above, 〔6〕By setting the reaction amount measured by the measuring method according to any one of 〔1〕 to 〔5〕 above to 3.0×10 -5 mol / g or more, a method for improving the dispersibility of silica in a rubber composition, 〔7〕The reaction amount measured by the measuring method according to any one of 〔1〕 to 〔5〕 above is 3.0×10 -5 mol / g or more, and the method for producing a rubber composition includes a step of adding silica to the unvulcanized rubber composition and mixing them, 〔8〕Relates to a method for producing a tire using the rubber composition produced by the production method according to 〔7〕 above.

Advantages of the Invention

[0011] According to the present invention, the reaction amount between the silane coupling agent and the rubber component in the rubber composition can be measured, and at the stage of the unvulcanized rubber composition, the dispersibility and other physical properties of silica can be predicted.

Brief Description of the Drawings

[0012] [Figure 1] It is a diagram showing an example of a solid 13C-NMR spectrum of an unvulcanized rubber composition.

Embodiments for Carrying Out the Invention

[0013] A method for measuring the reaction amount between a silane coupling agent and a rubber component in the rubber composition of the present invention comprises the steps of kneading a rubber component, a silane coupling agent, a vulcanizing agent, and a vulcanization accelerator without adding silica to obtain an unvulcanized or vulcanized rubber composition; performing an extraction treatment on the obtained rubber composition using a solvent in which the rubber component does not dissolve to extract the unreacted silane coupling agent contained in the rubber composition; and the solid of the rubber composition after extraction 13 measuring the solid by 13 13C-NMR, and quantifying the reaction amount from the ratio of the peak area of the carbon peak derived from a specific carbon atom of the rubber component to the peak area of the carbon peak derived from a specific carbon atom of the silane coupling agent in the obtained 13C-NMR spectrum.

[0014] Another embodiment of the present invention is to make the reaction amount between the silane coupling agent and the rubber component measured by the above method be 3.0×10 -5 mol / g or more to improve the dispersibility of silica in the rubber composition.

[0015] Another embodiment of the present invention is a method for producing a rubber composition, which includes a step of adding and mixing silica to the unvulcanized rubber composition in which the reaction amount between the silane coupling agent and the rubber component measured by the above method is 3.0×10 -5 mol / g or more.

[0016] Another embodiment of the present invention is to produce a tire using the rubber composition produced by the above production method.

[0017] A method for measuring the reaction amount between a silane coupling agent and a rubber component in a rubber composition, which is an embodiment of the present invention, will be described in detail below. However, the following description is for illustrative purposes to explain the present invention, and is not intended to limit the technical scope of the present invention only to this description scope. In this specification, when a numerical range is indicated using "~", both end values are included.

[0018] In this embodiment, there are no particular limitations on the rubber components that can be used. Crosslinkable rubber components commonly used in the rubber industry can be used, such as natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), ethylene propylene diene rubber (EPDM), styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. In particular, it is preferable to include a rubber component containing a carbon-carbon double bond, more preferably a rubber component containing a diene-based rubber, and even more preferably a rubber component containing a butadiene-based rubber. The butadiene-based rubber is not particularly limited as long as it is a polymer having a butadiene skeleton. These rubber components may be used individually or in combination of two or more.

[0019] The silica used in this embodiment is not particularly limited, and common silicas used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. These silicas may be used individually or in combination of two or more.

[0020] The nitrogen adsorption specific surface area (N2SA) of silica is 90 m² from the perspective of reinforcing properties. 2 Preferably 120m / g or more. 2 More preferably 150m / g or more, 2 More preferably 170m / g or more. 2 A value of 1 / g or more is particularly preferred. Furthermore, from the viewpoint of heat generation and processability, 350m 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m2 A value of less than or equal to / g is even more preferable. The N2SA of silica as used herein is the value measured by the BET method in accordance with ASTM D3037-93.

[0021] The average primary particle diameter of silica is preferably 22 nm or less, more preferably 20 nm or less, and even more preferably 18 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. By having the average primary particle diameter of silica within the above range, the dispersibility of silica can be further improved, and the reinforcing properties, fracture properties, wear resistance, etc., can be further improved. The average primary particle diameter of silica can be determined by observing it with a transmission or scanning electron microscope, measuring 400 or more primary silica particles observed within the field of view, and averaging the results.

[0022] The silica content relative to 100 parts by mass of rubber component is not particularly limited and can be, for example, 1 to 150 parts by mass, 5 to 120 parts by mass, or 10 to 100 parts by mass, depending on the purpose of the compounding.

[0023] The silane coupling agent according to this embodiment is not particularly limited, and any silane coupling agent that has been conventionally used in combination with silica in the rubber industry can be used, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(4-trimethoxysilylbutyl)tetrasulfide Trisulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-triethoxysilylbutyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(2-trimethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide , bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3 Sulfide-based silane coupling agents such as trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT-Z100, NXT-Z45, and NXT;Examples include thioester-based silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. These silane coupling agents may be used individually or in combination of two or more.

[0024] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of rubber component is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more. Furthermore, from the viewpoint of preventing a decrease in wear resistance, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0025] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more. Furthermore, from the viewpoint of preventing a decrease in wear resistance, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0026] Sulfur is preferably used as a vulcanizing agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0027] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0028] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane. These non-sulfur vulcanizing agents can be purchased commercially from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0029] While not particularly limited, examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators.

[0030] Examples of sulfenamide-based vulcanization accelerators include N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), N-(tert-butyl)-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazolyl sulfenamide, N,N'-diisopropyl-2-benzothiazolyl sulfenamide, and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide. Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole and dibenzothiazolyl disulfide. Examples of guanidine-based vulcanization accelerators include diphenylguanidine (DPG), diortotolylguanidine, and orthotolylbiguanidine. These vulcanization accelerators may be used individually or in combination of two or more.

[0031] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, even more preferably 6.0 parts by mass or less, and particularly preferably 5.0 parts by mass or less. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0032] In addition to the components mentioned above, the rubber composition according to this embodiment may appropriately contain compounding agents commonly used in the tire industry, such as carbon black, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other reinforcing fillers other than silica, resin components, liquid polymers, oils, waxes, processing aids, antioxidants, stearic acid, zinc oxide, and the like.

[0033] <Preparation of rubber composition> The measurement method according to this embodiment involves kneading a rubber component, a silane coupling agent, a vulcanizing agent, and a vulcanization accelerator without adding silica, and then solidifying the resulting rubber composition. 13 It is characterized by being subjected to 1C-NMR measurement. Solid 13¹¹C-NMR measurements may be performed on either the vulcanized rubber composition or the unvulcanized rubber composition. Furthermore, the rubber composition may contain compounding agents other than the rubber component, silane coupling agent, vulcanizing agent, and vulcanization accelerator.

[0034] solid 13 The unvulcanized rubber composition to be subjected to 1C-NMR measurement can be manufactured by known methods, except that silica is not added. For example, it can be manufactured by kneading each of the above components using rubber kneading equipment such as an open roll or closed kneader (Banbury mixer, kneader, etc.).

[0035] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a finish mixing process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. The mixing conditions are not particularly limited, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the finish mixing process, mixing is performed at 70 to 110°C for 1 to 5 minutes.

[0036] A vulcanized rubber composition can be obtained by vulcanizing the obtained unvulcanized rubber composition. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 120 to 200°C for 10 to 30 minutes can be used.

[0037] <Extraction process> The obtained unvulcanized or vulcanized rubber composition is subjected to an extraction treatment using a solvent. This extracts the unreacted silane coupling agent contained in the rubber composition and separates the unreacted and reacted silane coupling agent. That is, the unreacted silane coupling agent, which is a liquid, flows into the extractant by the solvent, while the reacted silane coupling agent, which is a solid, remains in the rubber composition, thereby separating the two.

[0038] The solvent is not particularly limited as long as it is an organic solvent that does not dissolve the rubber polymer component but dissolves the unreacted silane coupling agent. Examples include acetone, methyl ethyl ketone, methanol, ethanol, 1-propanol, 2-propanol, acetonitrile, etc., with acetone being preferred.

[0039] The extraction method described above is not particularly limited as long as it can extract unreacted silane coupling agents, but Soxhlet extraction is preferred from the viewpoint of being able to efficiently extract them from the rubber composition.

[0040] <Quantitative process> After drying the extracted rubber composition, it becomes a solid. 13 ¹ 13 The measurement conditions for 1C-NMR can be set, for example, as follows: (solid 13 C-NMR measurement conditions) Equipment: Bruker Avance400 Probe used: Bruker 7mm MAS BB WB WVT probe Resonance frequency 400MHz MAS rotation frequency 5kHz (±1Hz) Measurement mode DD / MAS Pulse train proton decoupled Hahn echo 90° pulse width, 4.5 μs Waiting time: 6 seconds Total number of times: 12,000 Observed temperature: 333K External reference substance: Adamantane (chemical shift value: 29.5 ppm)

[0041] The MAS rotation frequency is preferably 4kHz or higher, and more preferably 5kHz or higher, for a resonance frequency of 400MHz, in order to prevent overlap between the spinning sideband of the rubber peak and the peak originating from the >CH-CH2-O- bond. The waiting time is...13 A time of 1 to 30 seconds is preferred, and 5 to 30 seconds is more preferred, because it is more than five times the C T1 relaxation time. Furthermore, the number of cumulative cycles is preferably 1000 or more, and more preferably 3000 or more, in order to quantitatively discuss the peaks originating from specific carbon atoms of the silane coupling agent.

[0042] The obtained solid 13 From the 1C-NMR spectrum, the reaction amount between the silane coupling agent and the rubber component can be quantified based on the ratio of the peak area of ​​the carbon peak originating from a specific carbon atom in the rubber component to the peak area of ​​the carbon peak originating from a specific carbon atom in the silane coupling agent.

[0043] The carbon atoms derived from the rubber component for which the peak area is determined are not particularly limited, but carbon atoms that form double bonds in the rubber component are preferred. Examples include carbon atoms that form double bonds among the carbon atoms constituting the 1,4-butadiene bond unit of the rubber component, carbon atoms that form double bonds among the carbon atoms constituting the 1,2-butadiene bond unit of the rubber component, and carbon atoms that form double bonds among the carbon atoms constituting the 1,4-isoprene bond unit of the rubber component. Note that 1,4-butadiene bond units and 1,4-isoprene bond units contain both cis-1,4 bonds and trans-1,4 bonds, but in this embodiment, both are included.

[0044] The carbon peak originating from the carbon atom forming the double bond among the 1,4-butadiene bond units of the rubber component is observed at 123–134 ppm.

[0045] The carbon peak originating from the terminal carbon atoms of the vinyl group contained in the 1,2-butadiene bond unit of the rubber component is observed at 113–116 ppm.

[0046] The carbon peak originating from the quaternary carbon atom bonded to the methyl group among the carbon atoms constituting the 1,4-isoprene bond unit of the rubber component is observed at 134–136 ppm.

[0047] The carbon atoms derived from the silane coupling agent used to determine the peak area are not particularly limited as long as the detected peaks do not overlap with those of the rubber molecule. However, to minimize the influence of elimination due to hydrolysis, it is preferable that the carbon atoms are other than those constituting the alkoxysilyl portion of the silane coupling agent. Below, as an example, is the chemical structure of bis(3-triethoxysilylpropyl) disulfide.

[0048] [ka]

[0049] In the case of the above compounds, the carbon atoms constituting the alkoxysilyl moiety are the carbon atoms constituting the ethoxy group bonded to the silicon atom. The carbon atoms derived from the silane coupling agent for determining the peak area are preferably any carbon atom interposed between the silicon atom and the sulfur atom, and more preferably the carbon atom interposed between the silicon atom and the sulfur atom and located at the β position of the silicon atom (in the case of bis(3-triethoxysilylpropyl) disulfide, the carbon atom indicated by the arrow). The carbon peak originating from the carbon atom interposed between the silicon atom and the sulfur atom and located at the β position of the silicon atom is observed at 22.5 to 23.5 ppm.

[0050] In the rubber composition according to this embodiment, for example, when the peak area of ​​the carbon peak originating from the terminal carbon atom of the vinyl group contained in the 1,2-butadiene bond unit of the rubber component is set to 100, the peak area of ​​any carbon atom interposed between the silicon atom and the sulfur atom of the silane coupling agent (preferably the carbon atom interposed between the silicon atom and the sulfur atom and located at the β position of the silicon atom) is preferably 0.50 or more, more preferably 0.60 or more, and even more preferably 0.70 or more. By setting the peak area ratio within the above range, the amount of reaction between the silane coupling agent and the rubber component increases, and the dispersibility of silica tends to improve further.

[0051] In this embodiment, the reaction amount between the silane coupling agent and the rubber component in the rubber composition can be quantified by the method described above, thereby providing information necessary for optimizing the compounding, kneading, and vulcanization conditions to efficiently react the silane coupling agent.

[0052] The reaction amount between the silane coupling agent and the rubber component is set to 3.0 × 10⁻⁶ to improve silica dispersion. -5 Preferably 3.1 × 10 -5 More preferably 3.3 × 10 -5 More preferably 3.5 × 10 -5 A reaction ratio of mol / g or higher is particularly preferred. By setting the reaction amount between the silane coupling agent and the rubber component within the above range, the heat generation characteristics (low fuel consumption performance) of the rubber composition obtained by adding the vulcanization accelerator and vulcanizing agent to the unvulcanized rubber composition tend to be good. The reaction amount between the silane coupling agent and the rubber component can be determined, for example, by the method described in the following examples. Furthermore, the reaction amount can be appropriately adjusted by the number of remilling cycles, the mixing temperature, etc.

[0053] By adding silica and, if necessary, other compounding agents to the unvulcanized rubber composition subjected to measurement and kneading it according to a standard method, an unvulcanized rubber composition containing silica can be obtained. By heating and pressurizing this unvulcanized rubber composition according to a standard method, a vulcanized rubber composition containing silica can be obtained.

[0054] An unvulcanized rubber composition containing silica is extruded into the shape of a predetermined tire component, and this is then bonded to other components on a tire molding machine to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizing machine according to a standard method to obtain a tire.

[0055] The vulcanized rubber composition according to this embodiment is not particularly limited in its use, but is preferably used as a tire component such as a tread, sidewall, inner liner, or wing. [Examples]

[0056] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0057] The various chemicals used in the examples are summarized below. SBR: Nipol NS616 (unmodified S-SBR) manufactured by Nippon Zeon Co., Ltd. Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa. Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Wax: Ozoace 0355 (manufactured by Nippon Seiro Co., Ltd.) Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. (5% oil-containing powdered sulfur) Vulcanization accelerator 1: Noxellar CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noxellar D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0058] <Preparation of unvulcanized rubber composition> (Reference example 1) According to the formulation shown in Table 1, the mixture was kneaded for 5 minutes in a 1.7 L sealed Banbury mixer until the discharge temperature reached 170°C to obtain the unvulcanized rubber composition of Reference Example 1.

[0059] (Example 1) According to the formulation shown in Table 1, all chemicals except sulfur and vulcanization accelerator were mixed in a 1.7 L sealed Banbury mixer for 5 minutes until the discharge temperature reached 170°C to obtain a mixture. Next, using a twin-screw open roll mixer, sulfur and vulcanization accelerator were added to the mixture and mixed for 4 minutes until the temperature reached 105°C to obtain the unvulcanized rubber composition of Example 1.

[0060] <Measurement of the amount of bonding between silane coupling agent and polymer> Each of the obtained unvulcanized rubber compositions was subjected to the following conditions to solidify. 13 ¹¹¹ NMR is measured, solid 13 The 1C-NMR spectrum was obtained. 13 From the 13C-NMR spectrum, the peak area of ​​the carbon peak originating from the terminal carbon atom of the vinyl group contained in the 1,2-butadiene bond unit of the rubber component was set to 100. Based on the ratio of the peak area of ​​the carbon peak originating from the terminal carbon atom of the vinyl group contained in the 1,2-butadiene bond unit of the rubber component to the peak area of ​​the carbon atom indicated by the arrow in bis(3-triethoxysilylpropyl) disulfide, the reaction amount (mol / g) between the silane coupling agent and the rubber component was determined by the following formula. Each unvulcanized rubber composition was subjected to Soxhlet extraction with acetone for 12 hours, followed by drying at 60°C under vacuum for at least 1 hour before measurement. When the peak area of ​​the carbon peak originating from the terminal carbon atom of the vinyl group contained in the 1,2-butadiene bond unit of the rubber component was set to 100, the peak area of ​​the carbon atom indicated by the arrow in bis(3-triethoxysilylpropyl) disulfide was 0.61 for Reference Example 1 and 0.71 for Example 1. (Reaction amount (mol / g)) = (Peak area of ​​the peak originating from the carbon atom indicated by the arrow in bis(3-triethoxysilylpropyl) disulfide) / 2 / (Weight of rubber per 100 mol of styrene portion of SBR (g / mol) + Weight of rubber per 100 mol of 1,2-butadiene bond units of SBR (g / mol) + Weight of rubber per 100 mol of 1,4-butadiene bond units of SBR (g / mol))

[0061] [ka]

[0062] (solid 13 C-NMR measurement conditions) Equipment: Bruker Avance400 Probe used: Bruker 7mm MAS BB WB WVT probe Resonance frequency 400MHz MAS rotation frequency 5kHz (±1Hz) Measurement mode DD / MAS Pulse train proton decoupled Hahn echo 90° pulse width, 4.5 μs Waiting time: 6 seconds Total number of times: 12,000 Observed temperature: 333K External reference substance: Adamantane (chemical shift value: 29.5 ppm)

[0063] [Table 1]

[0064] As shown in the results in Table 1, similar reaction amounts could be calculated in the unvulcanized rubber composition, regardless of the presence or absence of vulcanizing agents and / or vulcanization accelerators.

[0065] According to the method for measuring the amount of silane coupling agent bonded to the silane coupling agent as described in this embodiment, the dispersibility and other physical properties of silica can be predicted at the stage of the unvulcanized rubber composition. Therefore, this method can be useful in finding suitable manufacturing conditions that fully bring out the performance of silica.

Claims

1. A method for measuring the reaction amount between a silane coupling agent and a rubber component in a rubber composition, A process of kneading rubber components, a silane coupling agent, a vulcanizing agent, and a vulcanization accelerator without adding silica to obtain an unvulcanized or vulcanized rubber composition; An extraction step is performed on the obtained rubber composition by extracting the unreacted silane coupling agent contained in the rubber composition using a solvent in which the rubber components do not dissolve; Solid rubber composition after extraction 13 The obtained solid was subjected to C-NMR. 13 A measurement method comprising a quantitative step of quantifying the reaction amount based on the ratio of the peak area of ​​the carbon peak originating from a specific carbon atom of the rubber component in the 13C NMR spectrum to the peak area of ​​the carbon peak originating from a specific carbon atom of the silane coupling agent.

2. The measurement method according to claim 1, wherein a specific carbon atom in the rubber component is a carbon atom that forms a double bond.

3. The measurement method according to claim 2, wherein the specific carbon atom of the silane coupling agent is a carbon atom other than the carbon atom constituting the alkoxysilyl moiety.

4. The measurement method according to claim 2, wherein the specific carbon atom of the silane coupling agent is any carbon atom interposed between a silicon atom and a sulfur atom.

5. solid 13 The measurement method according to claim 1, wherein the C-NMR measurement conditions are: measurement mode DD / MAS, waiting time 1 to 30 seconds, number of integrations 1000 or more, and MAS rotation frequency of 4 kHz or more at a resonance frequency of 400 MHz.

6. The reaction amount measured by the measurement method described in any one of claims 1 to 5 is 3.0 × 10 -5 A method for improving the dispersibility of silica in a rubber composition by setting the silica content to mol / g or higher.

7. The process includes the steps of obtaining an unvulcanized rubber composition, wherein the reaction amount measured by the measurement method described in any one of Claims 1 to 5 is 3.0 × 10 -5 A method for producing a rubber composition, comprising the step of adding silica to the unvulcanized rubber composition having a silica content of mol / g or more and mixing it.

8. A method for manufacturing a tire using a rubber composition manufactured by the manufacturing method described in claim 7.

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