JP2018162353A - Aromatic vinyl-conjugated diene copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aromatic vinyl-conjugated diene copolymer excellent in a balance between wet grip performance and fuel consumption saving performance.SOLUTION: The aromatic vinyl-conjugated diene copolymer has an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound, includes 80% or more of isolated aromatic vinyl unit based on the total amount of the aromatic vinyl unit and has a glass transition temperature width in the range of more than 10°C to less than 20°C in differential scanning calorimetry.SELECTED DRAWING: None

Description

  The present invention relates to an aromatic vinyl-conjugated diene copolymer.

  In recent years, due to increasing interest in environmental issues, polymer compositions used for automobile tires are also required to have excellent fuel economy, and in terms of safety, excellent wet grip performance is required. It has been demanded. As a polymer composition for an automobile tire, a polymer composition containing a conjugated diene polymer such as polybutadiene or styrene-butadiene copolymer and a filler such as carbon black or silica is used. .

  For example, Patent Documents 1 to 3 disclose styrene-butadiene copolymers having improved characteristics such as wet skid resistance, impact resilience, and road surface graspability.

JP-A-4-252242 JP-A-1-197541 JP-A-61-268710

  Aromatic vinyl-conjugated diene copolymers used for automobile tires are required to achieve both fuel economy and wet grip performance. Then, an object of this invention is to provide the aromatic vinyl-conjugated diene copolymer excellent in the balance of wet grip performance and fuel-saving performance.

  The present invention is an aromatic vinyl-conjugated diene copolymer having an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound, and based on the total amount of the aromatic vinyl unit, The present invention relates to an aromatic vinyl-conjugated diene copolymer containing 80% or more of isolated aromatic vinyl units and having a glass transition temperature range (ΔTg) in differential scanning calorimetry of greater than 10 ° C. and less than 20 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the aromatic vinyl conjugated diene copolymer excellent in the balance of wet grip performance and fuel-saving performance can be provided.

  This embodiment will be described in detail. In addition, this invention is not limited to the following embodiment.

[Aromatic vinyl-conjugated diene copolymer]
The aromatic vinyl-conjugated diene copolymer of the present embodiment has an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound, and based on the total amount of the aromatic vinyl unit, It contains 80% or more of isolated aromatic vinyl units, and the glass transition temperature width in differential scanning calorimetry is greater than 10 ° C. and less than 20 ° C.

  Here, the “isolated aromatic vinyl unit” means a structural unit in which the repeating aromatic vinyl unit in the copolymer chain is 1, that is, a structural unit in which the aromatic vinyl units are not continuously bonded to each other. Say. The greater the content of the isolated aromatic vinyl unit, the more the aromatic vinyl unit is present alone in the copolymer chain. A structural unit in which the number of repeating aromatic vinyl units in the copolymer chain is 2 or more, that is, a structural unit in which aromatic vinyl units are continuously bonded to each other is referred to as “long-chain aromatic vinyl”. When the long chain aromatic vinyl is increased, the aromatic vinyl unit tends to be unevenly distributed in a part of the copolymer chain.

  In the copolymer according to the present embodiment, the content ratio of the isolated aromatic vinyl unit is preferably 80 to 95%, more preferably 80 to 90%, based on the total amount of the aromatic vinyl unit. As the content of the isolated aromatic vinyl unit increases, the proportion of the aromatic vinyl unit present alone in the copolymer chain increases. When this ratio is 80% or more, the wet grip performance of the copolymer In addition, fuel saving performance can be improved.

The content ratio of the isolated aromatic vinyl unit in the copolymer chain can be determined by measuring ¹ H-NMR of the copolymer. Specifically, the content ratio of the isolated aromatic vinyl unit can be calculated by analyzing the sequence state of the aromatic vinyl unit in the NMR spectrum.

  The content ratio of the isolated aromatic vinyl unit can be adjusted by, for example, a method for controlling the polymerization reaction temperature or a method for continuously introducing a conjugated diene compound. In the method of controlling the polymerization reaction temperature, it is preferable to adjust the polymerization temperature so that the reaction rate of the aromatic vinyl compound and the reaction rate of the conjugated diene compound are kept equal. In the case of a method of continuously introducing a conjugated diene compound, a copolymer produced by reducing the initial supply amount of the conjugated diene compound and starting the reaction and then continuously supplying the remaining conjugated diene compound. It is preferable to appropriately adjust the ratio of the isolated aromatic vinyl units in the chain.

  As the glass transition temperature width (ΔTg) of the copolymer according to this embodiment is narrower, the aromatic vinyl units are uniformly distributed in the copolymer chain, and as ΔTg is wider, the aromatic vinyl unit is the copolymer chain. The structure is densely distributed somewhere. If ΔTg is large, the aromatic vinyl units are too ubiquitous anywhere in the copolymer chain, and it is difficult to obtain the fuel savings required in automotive tire applications. If ΔTg is too small, the aromatic vinyl units The distribution width is small and the wet grip performance is not sufficiently improved. From the viewpoint of further improving the balance between the wet grip performance and the fuel saving performance, the ΔTg of the copolymer according to the present embodiment is preferably 11 to 19 ° C, and more preferably 11 to 15 ° C.

  ΔTg can be measured using a differential scanning calorimeter (DSC). Specifically, in DSC measurement, after cooling a measurement sample to −100 ° C. in a nitrogen atmosphere, the temperature was raised from −100 ° C. to 100 ° C. at 10 ° C./min. , ΔTg can be calculated. ΔTg is the difference between the extrapolation start point and extrapolation end point of the baseline shift due to the transition of the heat flow curve, that is, the temperature difference between the inflection points in the glass transition temperature range.

The Mooney viscosity (ML _{1 + 4} ) of the copolymer according to this embodiment is preferably 10 or more, more preferably 20 or more, from the viewpoint of strength. Moreover, from a viewpoint of workability, Preferably it is 200 or less, More preferably, it is 150 or less. The Mooney viscosity (ML _{1 + 4} ) is measured at 125 ° C. according to JIS K6300 (1994).

The content of the aromatic vinyl unit of the copolymer according to this embodiment is preferably 100% by mass based on the total amount of the conjugated diene unit and the aromatic vinyl unit from the viewpoint of the balance between wet grip performance and fuel efficiency. Is 10 mass% or more and 50 mass% or less. Further, the vinyl bond content of the conjugated diene in the copolymer is preferably 10 mol% or more and 80 mol% or less, with the content of the conjugated diene unit being 100 mol% from the viewpoint of the balance between wet grip performance and fuel saving performance. It is. In applications where fuel saving performance is further required, it is more preferable that the content of aromatic vinyl units in the copolymer is less than 30% by mass and the vinyl bond content is 50% or more, and in applications where wet grip performance is further required. More preferably, the copolymer has an aromatic vinyl unit content of 30% by mass or more and a vinyl bond content of less than 50%. In applications where wet grip performance is more important, the copolymer may have an aromatic vinyl unit content of 30% by mass or more and a vinyl bond content of 50% or more. The vinyl bond amount is determined from the absorption intensity in the vicinity of 910 cm ^−1, which is the absorption peak of the vinyl group, by infrared spectroscopy.

  The molecular weight distribution of the copolymer according to the present embodiment is preferably 1 to 5, more preferably 1 to 2, from the viewpoint of fuel economy. The molecular weight distribution is obtained by measuring the number average molecular weight (Mn) and the weight average molecular weight (Mw) by gel permeation chromatography (GPC) method and dividing Mw by Mn. The Mw of the aromatic vinyl-conjugated diene copolymer is preferably 1 million or more, more preferably 1 million to 3 million, and still more preferably 1 million to 200, from the viewpoints of wet grip performance and wear resistance. Ten thousand. Mw and Mn can be measured by, for example, “Prominence” manufactured by Shimadzu Corporation. As the column, for example, “PLgel” manufactured by Agilent can be used. As the molecular weight standard substance, for example, standard polystyrene manufactured by Tosoh Corporation can be used.

  Hereinafter, each component which can be used for preparation of the copolymer which concerns on this embodiment is demonstrated. The copolymer according to the present embodiment can be produced by copolymerizing an aromatic vinyl compound and a conjugated diene compound using a polymerization initiator.

  Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-hexadiene, myrcene, and farnesene. The conjugated diene compound is preferably 1,3-butadiene or isoprene.

  Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, and divinyl naphthalene. As the aromatic vinyl compound, styrene is preferable.

  Examples of the polymerization initiator include a complex of an alkali metal and a polar compound, an oligomer having an alkali metal, an organic alkali metal compound, a Ziegler-Natta catalyst, and a metallocene catalyst. As the polymerization initiator, an organic alkali metal compound is preferable. The polymerization initiators may be used alone or in combination of two or more.

  Examples of the organic alkali metal compound include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2- Naphthyl lithium, 2-butylphenyl lithium, 4-phenylbutyl lithium, cyclohexyl lithium, cyclopentyl lithium, 1,4-dilithio-2-butene, 1,3,3-trilithiooctyne, sodium naphthalenide, sodium biphenylide and Organic alkali metal compounds having a hydrocarbyl group such as potassium naphthalenide; methylaminopropyl lithium, diethylaminopropyl lithium, tert-butyldimethylsilyloxypropyl lithium, N-molybdenum Reaction of isoprene to holinopropyllithium, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, 3- (dimethylamino) propyllithium or 3- (diethylamino) propyllithium And an organic alkali metal compound having a group containing a nitrogen atom, such as a compound obtained by heating. The organic alkali metal compound is preferably n-butyllithium.

  The amount of the polymerization initiator used is preferably 0.01 mmol to 15 mmol per 100 g of the total amount of the aromatic vinyl compound and the conjugated diene compound.

  The copolymerization of the aromatic vinyl compound and the conjugated diene compound is preferably performed in a solvent. As the solvent, a solvent that does not deactivate the polymerization initiator may be used, and a hydrocarbon solvent is preferable. As the hydrocarbon solvent, aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, and the like can be used. A solvent may be used individually or in combination of 2 or more types, and the mixture of aliphatic hydrocarbons and alicyclic hydrocarbons like industrial hexane may be used.

  Examples of the aliphatic hydrocarbon include propane, n-butane, iso-butane, n-pentane, iso-pentane, 2-methylpentane, 3-methylpentane, n-hexane, propene, 1-butene and iso-butene. , Trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene and 2-hexene. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, and ethylbenzene. Examples of the alicyclic hydrocarbon include cyclopentane, cyclohexane, and methylcyclopentane.

  In addition, from the viewpoint of improving fuel saving performance and wear resistance performance, the copolymer has a unit based on a modifier having a hetero atom and / or a silicon atom at least at the start end, in the chain, or at the stop end of the copolymer. May be.

  The preparation of the copolymer according to the present embodiment includes an agent that adjusts the vinyl bond amount of the conjugated diene unit, an agent that adjusts the distribution of the conjugated diene unit and the aromatic vinyl unit in the copolymer chain (hereinafter, generic name). And may be carried out in the presence of “regulator”.

  As the regulator, ether compounds, tertiary amines, phosphine compounds, alkali metal alkoxides, alkali metal phenoxides, and the like can be used. Examples of ether compounds include cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane; aliphatic monoethers such as diethyl ether and dibutyl ether; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether. Aliphatic diethers; aliphatic triethers such as diethylene glycol diethyl ether and diethylene glycol dibutyl ether; aromatic ethers such as diphenyl ether, anisole, 1,2-dimethoxybenzene, and 3,4-dimethoxytoluene. Examples of the tertiary amine include triethylamine, tripropylamine, tributylamine, 1,1,2,2-tetramethylethylenediamine, N, N-diethylaniline, pyridine and quinoline. Examples of the phosphine compound include trimethylphosphine, triethylphosphine, and triphenylphosphine. Examples of the alkali metal alkoxide include sodium-tert-butoxide, potassium-tert-butoxide, sodium-tert-pentoxide and potassium-tert-pentoxide. Examples of the alkali metal phenoxide include sodium phenoxide and potassium phenoxide. You may use these individually or in combination of 2 or more types.

[Polymer composition]
A polymer composition may be prepared by blending a reinforcing material with the aromatic vinyl-conjugated diene copolymer of the present embodiment.

  Examples of the reinforcing material include silica, calcium silicate, aluminum silicate, aluminum hydroxide, and carbon black. You may use a reinforcing material individually or in combination of 2 or more types.

Examples of silica include dry silica (anhydrous silicic acid), wet silica (hydrous silicic acid), colloidal silica, and precipitated silica. BET specific surface area of silica is ^{preferably, 50m 2 / g~250m 2 / g} . The BET specific surface area is measured according to ASTM D1993-03. As commercial products of silica, trade names “Ultrasil VN3-G” manufactured by Degussa, trade names “VN3”, “AQ”, “ER”, “RS-150”, manufactured by Rhodia, manufactured by Tosoh Silica Product names such as “Zeosil 1115MP”, “Zeosil 1165MP”, etc. can be used. Silica may be used alone or in combination of two or more.

  Examples of carbon black include furnace black, acetylene black, thermal black, channel black, and graphite. Examples of channel black include EPC, MPC, and CC. Examples of the furnace carbon black include SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF. Examples of the thermal black include FT and MT. Carbon blacks may be used alone or in combination of two or more.

Nitrogen adsorption specific surface area _(N 2 SA) of carbon black is ^{preferably, 5m 2 / g~200m 2 / g} . Carbon black has a dibutyl phthalate (DBP) absorption amount of preferably 5 mL / 100 g to 300 mL / 100 g. The nitrogen adsorption specific surface area can be measured according to ASTM D4820-93, and the DBP absorption amount can be measured according to ASTM D2414-93. Commercially available carbon black products are trade names “Diamond Black N339” manufactured by Mitsubishi Chemical Corporation, “Seast 6”, “Seast 7HM”, “Seast KH” manufactured by Tokai Carbon Co., and product names “Degussa” manufactured by Degussa. CK 3 "," Special Black 4A ", etc. can be used.

  The content of the reinforcing material in the polymer composition is 10 parts by mass or more, preferably 20 parts by mass or more, more preferably from the viewpoint of improving wet grip performance with respect to 100 parts by mass of the copolymer. 30 parts by mass or more. Moreover, in order to improve reinforcement property, content of a reinforcing material is 150 mass parts or less, Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less.

  The copolymer according to this embodiment may be further blended with other polymer components, additives and the like to prepare a polymer composition.

  Examples of other polymer components include conventional styrene-butadiene copolymer rubber, polybutadiene rubber, butadiene-isoprene copolymer rubber, butyl rubber, natural rubber, ethylene-propylene copolymer, and ethylene-octene copolymer. Can be mentioned. These polymer components may be used alone or in combination of two or more.

  In the case where other polymer components are blended, the content of the copolymer according to the present embodiment in the polymer composition is determined based on the total amount of polymer components (aromatic vinyl-conjugated diene copolymer) from the viewpoint of improving wet grip performance. The amount is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass (including coalescence).

  Known additives can be used, such as sulfur vulcanizing agents; thiazole vulcanization accelerators, thiuram vulcanization accelerators, sulfenamide vulcanization accelerators, guanidine vulcanization accelerators. Examples thereof include vulcanization accelerators such as stearic acid and zinc oxide; organic peroxides; silane coupling agents; extension oils; processing aids;

  Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidoxypropyltrimethoxy. Silane, γ-methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ -Aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (tri Ethoxysilyl Propyl) tetrasulfide, .gamma.-trimethoxysilylpropyl dimethylthiocarbamoyl tetrasulfide and .gamma.-trimethoxysilylpropyl benzothiazyl tetrasulfide and the like. You may use a silane coupling agent individually or in combination of 2 or more types. As commercial products, trade names “Si69”, “Si75”, etc., manufactured by Degussa can be used.

  The compounding amount of the silane coupling agent is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and further preferably 5 to 10 parts by mass with respect to 100 parts by mass of the reinforcing material.

  Examples of the extending oil include aromatic mineral oil (viscosity specific gravity constant (VGC value) 0.900 to 1.049), naphthenic mineral oil (VGC value 0.850). -0.899) and paraffinic mineral oil (VGC value 0.790-0.849). The polycyclic aromatic content of the extender oil is preferably less than 3% by mass, more preferably less than 1% by mass. The polycyclic aromatic content is measured according to the British Petroleum Institute 346/92 method. The aromatic compound content (CA) of the extender oil is preferably 20% by mass or more. The extension oils may be used alone or in combination of two or more.

  Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethyl Thiuram vulcanization accelerators such as thiuram disulfide; N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, Sulfenamide vulcanization accelerators such as N-oxyethylene-2-benzothiazole sulfenamide and N, N′-diisopropyl-2-benzothiazole sulfenamide; diphenylguanidine, dioltolylguanidine, orthotolylbiguanidine etc Guanidine-based vulcanization accelerator and the like. Vulcanization accelerators may be used alone or in combination of two or more.

  The blending amount of the vulcanization accelerator is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the polymer component.

  As a method for producing the polymer composition according to this embodiment, a known method, for example, a method of kneading each component with a known mixer such as a roll or a Banbury mixer may be used.

  As kneading conditions, when additives other than the vulcanizing agent and the vulcanization accelerator are blended, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30 seconds. -30 minutes, preferably 1-30 minutes. When blending a vulcanizing agent and a vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. A composition containing a vulcanizing agent and a vulcanization accelerator is usually used after being subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

  The polymer composition according to the present embodiment has a balance between excellent wet grip performance and fuel economy, and is suitably used for automobile tires.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

The physical properties were evaluated by the following method.
1. Mooney viscosity (ML _{1 + 4} )
According to JIS K6300 (1994), the initial Mooney viscosity of the copolymer was measured at 125 ° C.

2. Vinyl bond amount (unit: mol%)
The amount of vinyl bond of the conjugated diene in the copolymer was determined from the absorption intensity near 910 cm ^−1, which is the absorption peak of the vinyl group, by infrared spectroscopy.

3. Styrene unit content (unit: mass%)
According to JIS K6383 (1995), the content of styrene units in the copolymer was determined from the refractive index.

4). Weight average molecular weight (Mw)
Mw was measured by the gel permeation chromatograph (GPC) method under the following conditions (1) to (8).
(1) Equipment: Prominence made by Shimadzu Corporation
(2) Separation columns: Agilent PLgel 5 μm 10 ⁵ Å, PLgel 5 μm 10 ⁶ Å (each one connected)
(3) Measurement temperature: 40 ° C
(4) Carrier: Tetrahydrofuran (5) Flow rate: 1.0 mL / min (6) Injection volume: 100 μL
(7) Detector: Differential refraction (8) Molecular weight standard: Standard polystyrene

4). Content ratio of isolated styrene units (unit:%)
Using deuterated chloroform as a solvent, 400 MHz ¹ H-NMR (manufactured by JEOL Ltd., AL400) was measured, and the structure of the copolymer was analyzed. From the obtained NMR spectrum, the sequence state of the styrene unit was determined from the integrated value in the following range. The content ratio of the isolated styrene unit is the meta position of the aromatic ring determined from (b) and (c) based on the integrated value of (a) below with respect to the total integrated value of (a) to (c) below: It was set as the ratio of the integral value which subtracted the calculated value of the para-position proton.
(A) Isolated styrene unit, 2-3 chain styrene, 4 chain or more styrene: integrated value of peak between 7.6 and 7.0 ppm.
(B) 2-3 chain styrene (ortho proton): integrated value of peak between 7.0 and 6.9 ppm.
(C) 4 or more chain styrene (ortho position proton): integrated value of peak between 6.9 and 6.0 ppm.

5. Glass transition temperature range (ΔTg)
Using a differential scanning calorimeter DSC7020 manufactured by Hitachi High-Tech Science Co., Ltd., the copolymer was cooled to −100 ° C. in a nitrogen atmosphere, and then measured under the condition of raising the temperature to 100 ° C. at 10 ° C./min. The difference between the extrapolation start point and the extrapolation end point of the baseline shift due to the transition of the obtained heat flow curve was read as ΔTg.

6). Wet Grip Performance A strip-shaped test piece having a width of 1 mm or 2 mm and a length of 40 mm was punched out from a sheet-like vulcanized molded body and used for the test. The measurement was performed by measuring the loss tangent (tan δ (0 ° C.)) of the test piece at a temperature of 0 ° C. under the conditions of a strain of 2.5% and a frequency of 10 Hz using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho). The larger this value, the better the wet grip performance.

7). Fuel-saving performance A strip-shaped test piece having a width of 1 mm or 2 mm and a length of 40 mm was punched out from the sheet-like vulcanized molded article and used for the test. The measurement was performed by measuring the loss tangent (tan δ (70 ° C.)) of the test piece at a temperature of 70 ° C. under the conditions of a strain of 1% and a frequency of 10 Hz using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho). The smaller this value, the better the fuel saving performance.

[Example 1]
<Preparation of aromatic vinyl-conjugated diene copolymer>
A stainless polymerization reactor with an internal volume of 20 L equipped with a stirrer was washed and dried, and the atmosphere inside the polymerization reactor was replaced with dry nitrogen. Next, 7.65 kg of industrial hexane (manufactured by Sumitomo Chemical Co., Ltd., trade name: hexane (general product), density 0.68 g / mL), 2.93 kg of cyclohexane, 240 g of 1,3-butadiene, 510 g of styrene, 8. 8 mL and ethylene glycol dibutyl ether 0.9 mL were charged into the polymerization reactor. Next, in order to preliminarily detoxify impurities that act on the deactivation of the polymerization initiator, a small amount of n-butyllithium (n-BuLi) hexane solution was introduced into the polymerization reactor as a scavenger, and then n-BuLi. Was added to the polymerization reactor to start the polymerization reaction.

  The polymerization reaction was carried out for 4 hours and 10 minutes. During the polymerization reaction, the temperature in the polymerization reactor is adjusted to 65 ° C., and the solution in the polymerization reactor is stirred at a stirring speed of 100 rpm. In the polymerization reactor, after 20 minutes from the start of polymerization, it takes 3 hours and 20 minutes. 660 g of 1,3-butadiene and 90 g of styrene were continuously supplied. Next, while maintaining the polymerization reactor temperature at 65 ° C., the obtained polymerization solution was stirred in the polymerization reactor at a stirring speed of 100 rpm, and 0.25 mmol of silicon tetrachloride was added to the polymerization solution and stirred for 15 minutes. Next, 5 mL of a hexane solution containing 0.8 mL of methanol was charged into the polymerization reactor, and the polymerization solution was stirred for 5 minutes.

  A copolymer obtained by withdrawing the stirred product from the polymerization reactor, drying a part of the stirred product at room temperature for 24 hours, evaporating most of the volatile matter, and further drying under reduced pressure at 55 ° C. for 12 hours. The vinyl bond content, styrene unit content, ΔTg, and isolated styrene unit content were measured.

  To the stirred product, 6.0 g of 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer GM), Pentaerythrityl tetrakis (3-lauryl thiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer TP-D) 3.0 g and extension oil (manufactured by Japan Energy Co., Ltd., trade name: JOMO process NC-140) 5 g was added to obtain a mixture. Next, most of the volatile components in the mixture were evaporated at room temperature for 24 hours and further dried under reduced pressure at 55 ° C. for 12 hours to obtain an aromatic vinyl-conjugated diene copolymer 1.

<Preparation of polymer composition>
110 parts by mass of copolymer 1, 20 parts by mass of polybutadiene rubber (manufactured by LANXESS, trade name: Buna CB24), 75.0 parts by mass of silica (manufactured by Degussa, trade name: Ultrasil VN3-G), silane 6.0 parts by mass of coupling agent (Degussa, trade name: Si75), 10.0 parts by weight of carbon black (Mitsubishi Chemical, trade name: Diamond Black N339), extension oil (manufactured by Japan Energy, Product name: JOMO process NC-140) 10.0 parts by weight, anti-aging agent (manufactured by Sumitomo Chemical Co., Ltd., trade name: Antigen 6C) 2.0 parts by weight, wax (manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name) : Sunnock N) 2.0 parts by mass, Wax (trade name: EF44, trade name: EF44) 1.0 parts by mass, stearic acid 2.0 parts by mass, zinc white 3.0 parts by mass, laboratory The polymer composition was prepared by kneading with a plast mill.

<Preparation of vulcanized sheet>
To 241 parts by mass of the polymer composition, 1.5 parts by mass of a vulcanization accelerator (manufactured by Sumitomo Chemical Co., Ltd., trade name: Soxinol CZ), vulcanization accelerator (manufactured by Sumitomo Chemical Co., Ltd., trade name: Soxinol D) 2.0 Part by mass and 1.5 parts by mass of sulfur were added, formed into a sheet with a 6-inch roll, and the sheet was heated and vulcanized at 160 ° C. for 40 minutes to prepare a vulcanized sheet.

[Example 2]
<Preparation of aromatic vinyl-conjugated diene copolymer>
A stainless polymerization reactor with an internal volume of 20 L equipped with a stirrer was washed and dried, and the atmosphere inside the polymerization reactor was replaced with dry nitrogen. Next, 7.65 kg of “hexane (general product)”, 2.93 kg of cyclohexane, 298 g of 1,3-butadiene, 553 g of styrene, 8.8 mL of tetrahydrofuran and 0.9 mL of ethylene glycol dibutyl ether were charged into the polymerization reactor. Next, a hexane solution of n-BuLi was charged into the polymerization reactor, and then an n-hexane solution containing 3.06 mmol of n-BuLi was charged into the polymerization reactor to initiate the polymerization reaction.

  The polymerization reaction was carried out for 4 hours and 10 minutes. During the polymerization reaction, the temperature in the polymerization reactor is adjusted to 65 ° C., and the solution in the polymerization reactor is stirred at a stirring speed of 130 rpm. In the polymerization reactor, after 20 minutes from the start of polymerization, it takes 3 hours and 20 minutes. 630 g of 1,3-butadiene and 66 g of styrene were continuously supplied. Next, while maintaining the polymerization reactor temperature at 65 ° C., the obtained polymerization solution was stirred in the polymerization reactor at a stirring speed of 130 rpm, 0.27 mmol of silicon tetrachloride was added to the polymerization solution, and the mixture was stirred for 15 minutes. Next, 5 mL of a hexane solution containing 0.8 mL of methanol was charged into the polymerization reactor, and the polymer solution was stirred for 5 minutes.

  A copolymer obtained by withdrawing the stirred product from the polymerization reactor, drying a part of the stirred product at room temperature for 24 hours, evaporating most of the volatile matter, and further drying under reduced pressure at 55 ° C. for 12 hours. The vinyl bond content, styrene unit content, ΔTg, and isolated styrene unit content were measured.

  6.2 g of “Sumilizer GM”, 3.1 g of “Sumilizer TP-D” and 580 g of “JOMO Process NC-140” were added to the stirred product to obtain a mixture. Next, most of the volatile components in the mixture were evaporated at room temperature for 24 hours, and further dried under reduced pressure at 55 ° C. for 12 hours to obtain a conjugated diene copolymer 2.

<Preparation of polymer composition and production of vulcanized sheet>
A polymer composition was prepared and a vulcanized sheet was produced in the same manner as in Example 1 except that the copolymer 2 was used.

[Comparative Example 1]
<Preparation of aromatic vinyl-conjugated diene copolymer>
A stainless polymerization reactor with an internal volume of 20 L equipped with a stirrer was washed and dried, and the atmosphere inside the polymerization reactor was replaced with dry nitrogen. Next, 7.65 kg of “hexane (general product)”, 2.93 kg of cyclohexane, 240 g of 1,3-butadiene, 360 g of styrene, 8.8 mL of tetrahydrofuran and 0.9 mL of ethylene glycol dibutyl ether were charged into the polymerization reactor. Next, a hexane solution of n-BuLi was charged into the polymerization reactor, and then an n-hexane solution containing 2.64 mmol of n-BuLi was charged into the polymerization reactor to initiate the polymerization reaction.

  The polymerization reaction was carried out for 4 hours and 10 minutes. During the polymerization reaction, the temperature in the polymerization reactor is adjusted to 65 ° C., and the solution in the polymerization reactor is stirred at a stirring speed of 130 rpm. In the polymerization reactor, after 20 minutes from the start of polymerization, it takes 3 hours and 20 minutes. 480 g of 1,3-butadiene and 120 g of styrene were continuously supplied. Next, while maintaining the polymerization reactor temperature at 65 ° C., the obtained polymerization solution was stirred in the polymerization reactor at a stirring speed of 130 rpm, 0.24 mmol of silicon tetrachloride was added to the polymerization solution, and the mixture was stirred for 15 minutes. Next, 5 mL of a hexane solution containing 0.8 mL of methanol was charged into the polymerization reactor, and the polymer solution was stirred for 5 minutes.

  A copolymer obtained by withdrawing the stirred product from the polymerization reactor, drying a part of the stirred product at room temperature for 24 hours, evaporating most of the volatile matter, and further drying under reduced pressure at 55 ° C. for 12 hours. The vinyl bond content, styrene unit content, ΔTg, and isolated styrene unit content were measured.

  7.2 g of “Smilizer GM”, 3.6 g of “Sumilyzer TP-D” and 450 g of “JOMO Process NC-140” were added to the stirred product to obtain a mixture. Next, most of the volatile components in the mixture were evaporated at room temperature for 24 hours, and further dried under reduced pressure at 55 ° C. for 12 hours to obtain a conjugated diene copolymer C1.

<Preparation of polymer composition and production of vulcanized sheet>
A polymer composition was prepared and a vulcanized sheet was produced in the same manner as in Example 1 except that the copolymer C1 was used.

[Comparative Example 2]
<Preparation of aromatic vinyl-conjugated diene copolymer>
A stainless polymerization reactor with an internal volume of 20 L equipped with a stirrer was washed and dried, and the atmosphere inside the polymerization reactor was replaced with dry nitrogen. Next, 7.65 kg of “hexane (general product)”, 2.93 kg of cyclohexane, 240 g of 1,3-butadiene, 360 g of styrene, 8.8 mL of tetrahydrofuran and 0.9 mL of ethylene glycol dibutyl ether were charged into the polymerization reactor. Next, a hexane solution of n-BuLi was charged into the polymerization reactor, and then an n-hexane solution containing 3.12 mmol of n-BuLi was charged into the polymerization reactor to initiate the polymerization reaction.

  The polymerization reaction was carried out for 4 hours and 10 minutes. During the polymerization reaction, the temperature in the polymerization reactor is adjusted to 65 ° C., the solution in the polymerization reactor is stirred at a stirring speed of 130 rpm, and 540 g of 1,3-butadiene and 360 g of styrene are added in the polymerization reactor for 2 hours. Feeded continuously over 30 minutes. Next, while maintaining the polymerization reactor temperature at 65 ° C., the obtained polymerization solution was stirred in the polymerization reactor at a stirring speed of 130 rpm, and 0.25 mmol of silicon tetrachloride was added to the polymerization solution and stirred for 15 minutes. Next, 5 mL of a hexane solution containing 0.8 mL of methanol was charged into the polymerization reactor, and the polymer solution was stirred for 5 minutes.

  A copolymer obtained by withdrawing the stirred product from the polymerization reactor, drying a part of the stirred product at room temperature for 24 hours, evaporating most of the volatile matter, and further drying under reduced pressure at 55 ° C. for 12 hours. The vinyl bond content, styrene unit content, ΔTg, and isolated styrene unit content were measured.

  To the stirred product, 8.0 g of “Sumizer GM”, 4.0 g of “Sumizer TP-D” and 562.5 g of “JOMO Process NC-140” were added to obtain a mixture. Next, most of the volatile matter in the mixture was evaporated at room temperature for 24 hours, and further dried under reduced pressure at 55 ° C. for 12 hours to obtain a conjugated diene copolymer C2.

<Preparation of polymer composition and production of vulcanized sheet>
A polymer composition was prepared and a vulcanized sheet was prepared in the same manner as in Example 1 except that the copolymer C2 was used.

  Evaluation of vinyl bond content, styrene unit content, ΔTg before adding extension oil, content ratio of isolated styrene unit, wet grip performance of vulcanized sheet and fuel economy performance of copolymers obtained in Examples and Comparative Examples The results are shown in Table 1. The wet grip performance and the fuel saving performance are relative values with Comparative Example 1 being 100, and the larger the numerical value, the better the wet grip performance and the fuel saving performance.

Claims (3)

An aromatic vinyl-conjugated diene copolymer having an aromatic vinyl unit based on an aromatic vinyl compound and a conjugated diene unit based on a conjugated diene compound,
Based on the total amount of the aromatic vinyl units, containing 80% or more of isolated aromatic vinyl units,
An aromatic vinyl-conjugated diene copolymer having a glass transition temperature width in a differential scanning calorimetry of greater than 10 ° C. and less than 20 ° C.   The aromatic vinyl-conjugated diene copolymer according to claim 1, having a weight average molecular weight of 1,000,000 or more.   The content of the aromatic vinyl unit is 10% by mass or more and 50% by mass or less, with the total amount of the conjugated diene unit and the aromatic vinyl unit being 100% by mass, and the vinyl bond of the conjugated diene in the copolymer The aromatic vinyl-conjugated diene copolymer according to claim 1 or 2, wherein the amount is 10 mol% or more and 80 mol% or less, where the content of the conjugated diene unit is 100 mol%.