JP3412534B2 - Rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition. More specifically, it is a rubber composition containing a diene rubber as a main component of a rubber component, wherein a specific styrene-butadiene copolymer is previously used as a component of the diene rubber by using a specific amount of extender oil. The present invention relates to a rubber composition containing a specific amount of an oil-extended product and excellent in low rolling resistance, high wet skid resistance and abrasion resistance, and particularly suitable for a vulcanized rubber for a tire tread.

[0002]

2. Description of the Related Art In recent years, a rubber material for tires has been desired which reduces rolling resistance of tires in response to a demand for low fuel consumption of automobiles. In order to reduce the rolling resistance of this tire, the energy loss of the vulcanized rubber at low frequencies may be reduced. That is, the tire temperature of a running automobile is 50 ° C. to 70 ° C. At that time, the frequency of the external force received by the tire (tread rubber) (determined from the vehicle speed and the diameter of the tire) is several tens Hz, and this temperature and The smaller the energy loss under this low frequency condition, the better the fuel consumption. As described above, the concept of "energy loss of vulcanized rubber at low frequencies" is an index for vulcanized rubber evaluation regarding fuel economy under actual use conditions of tires. As a vulcanized rubber evaluation index (lab index) relating to fuel economy when the actual running conditions are reproduced in a laboratory, there is "tan δ at 60 ° C (tan δ indicates energy loss)", and this "tan δ at 60 ° C" The smaller the value, the better the fuel consumption.

[0003] On the other hand, there is a demand of improving the running stability of the vehicle, along with this request, the frictional resistance on a wet road surface of the tire (wet grips) and the frictional resistance of a dry road surface of the tire (dry grip) There is a strong demand for a rubber material for tires that increases the fuel consumption. In order to increase the frictional resistance of the tire on the road surface (particularly on the wet road surface), the energy loss of the vulcanized rubber at high frequencies may be increased. That is, when an automobile brakes, the tire temperature of the automobile becomes 50 ° C to 70 ° C, but at that time, the tire (tread rubber) has a high frequency (tens of thousands to several hundreds of thousands) due to invisible unevenness of the road surface. The external force is applied to the tire at a frequency (Hz), and the larger the energy loss under this temperature and the higher frequency condition, the larger the frictional resistance on the road surface (the tire having excellent gripping force). In this way, the concept of "energy loss of vulcanized rubber at high frequencies" is an evaluation index for vulcanized rubber regarding the grip force in the actual use conditions of tires. Since it is difficult to obtain a tester that measures at such a high frequency, it cannot be used as it is as a laboratory index of vulcanized rubber for grip strength. Therefore, the frequency is converted into temperature (under the condition that the frequency is reduced and the temperature is reduced by that amount), that is, "tan δ at 0 ° C" is measured, and is used as a laboratory index of the vulcanized rubber regarding the grip force. The larger the “tan δ at 0 ° C.”, the better the tire grip.

As can be seen from the above, low rolling resistance (low fuel consumption) and high frictional resistance on wet road surfaces (improvement in running stability) are in a trade-off relationship, and it is not possible to make these physical properties compatible with each other. It was difficult. Up to now, various rubber materials have been proposed in order to make these physical properties compatible with each other. For example, a copolymer obtained by copolymerizing a conjugated diolefin and an aromatic vinyl compound using a lithium amide initiator (JP-A-6-279,515) and a heavy polymer obtained using an organolithium initiator. A rubber composition containing a styrene-butadiene copolymer modified or coupled at the polymer end (JP-A 1-222940) and a styrene-butadiene rubber and vinyl polybutadiene (JP-A 9-183868). Etc. However, these rubber materials have not been able to sufficiently satisfy the recent requirements for both physical properties.

Further, regarding the reduction of fuel consumption (improvement of fuel consumption), in addition to the above-mentioned demand for low rolling resistance, there is also a strong demand for weight reduction of tires, and along with this, the emergence of vulcanized rubber having excellent wear characteristics is desired. It is rare. That is, as described above, a method for realizing low fuel consumption (improvement in fuel consumption) is to reduce the energy loss (tan δ at 60 ° C.) of the rubber itself used for the tread, and to reduce the tire thickness. There are two ways to reduce the weight of the tire by reducing the weight of the tire, and the weight reduction (thinning) of the tire inevitably involves the thinning of the tread portion, so in order to avoid shortening the tire life, The advent of vulcanized rubber with improved wear properties is desired. However, as described above, by realizing a rubber material for tires having both physical properties of low rolling resistance (low rolling resistance) and high friction resistance on wet road surfaces (high wet skid resistance). Moreover, there is a problem that it is extremely difficult to realize a rubber material having improved wear characteristics (wear resistance) as well as being difficult.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and is excellent in low rolling resistance, high wet skid resistance and wear resistance, and particularly for high performance tires. An object of the present invention is to provide a rubber composition suitable for use in a vulcanized rubber for a fuel tread with low fuel consumption.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies and as a result, as a component of a diene rubber, a specific styrene-butadiene copolymer was used in advance with a specific amount of extender oil. It was found that a rubber composition excellent in both low rolling resistance, high wet skid resistance and abrasion resistance can be obtained by containing a specific amount of the oil-extended product, thus completing the present invention. Let
That is, the present invention has the following configurations.

[1] In a rubber composition containing a diene rubber as a main component of a rubber component, a styrene-butadiene copolymer having the following characteristics (a) to (d) as one component of the diene rubber: 30% to 100% by weight of the rubber component, which has been oil-extended with an extension oil in advance, and (a) the styrene content is 5 to 45% by weight. (B) 1 of the microstructure of the butadiene part , 2-bond content is 20 to 80%, (c) glass transition temperature is -55 ° C to -20 ° C, (d) one single chain in the styrene unit is a fully bonded styrene. 40% by weight or more, and 8% or more of styrene long chains are 10% by weight or less of the total bound styrene,
Further, the content (extended amount) of the extending oil used for pre-extending the styrene-butadiene copolymer is
20 per 100 parts by weight of styrene-butadiene copolymer
The content of total extender oil in all rubber components is 10 to 5 parts by weight based on 100 parts by weight of all rubber components.
A rubber composition comprising 0 parts by weight.

[2] The rubber composition according to [1], wherein the styrene-butadiene copolymer further has the following characteristic (e). (E) The polymer terminal is modified with one or more polyfunctional coupling agents selected from the group consisting of halogen-containing silicon compounds, alkoxysilane compounds and alkoxysulfide compounds.

[3] The rubber composition as described in [1] or [2], wherein the styrene-butadiene copolymer further has the following characteristic (f).
(F) The molecular weight distribution is 1.5 to 3.0.

[4] The rubber composition as a filler is 2 to 100 parts by weight of carbon black and / or 30 to 100 parts by weight of silica to 100 parts by weight of all rubber components as a filler. And contains
When containing silica, it is 5 to 100 parts by weight of silica.
The rubber composition according to any one of [1] to [3], which contains 20 parts by weight of a silane coupling agent.

[5] The rubber composition as described in any of [1] to [4], wherein the rubber composition is used for a vulcanized rubber for a tire tread.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. (I) Rubber composition The rubber composition of the present invention contains a diene rubber as a main component of a rubber component, and a specific styrene-butadiene copolymer is used as a component of the diene rubber in advance with an extender oil. The oil-extended product is contained in a specific amount. 1. Rubber Component (1) Diene Rubber The rubber composition of the present invention contains a diene rubber as the main component of the rubber component, and contains a styrene-butadiene copolymer as one component of the diene rubber. Styrene-Butadiene Copolymer (i) Characteristics The styrene-butadiene copolymer used in the present invention is
It has the following characteristics (a) to (d) and, if necessary, preferably characteristics (e) to (g).

The following characteristics (a) to be used in the present invention:
(D) and, if necessary, preferably the properties (e) to
The styrene-butadiene copolymer having (g) is preferably obtained by copolymerizing styrene and butadiene with a lithium-based initiator. The initiator used in the copolymerization of styrene and butadiene is not particularly limited, but it is preferable to use a lithium-based initiator from the viewpoint of low cost and stability of polymerization. The lithium-based initiator is preferably an organic lithium compound. Examples of the organolithium compound include alkyllithium such as n-butyllithium, sec-butyllithium and t-butyllithium; alkylenedilithium such as 1,4-dilithiumbutane; phenyllithium, stilbenelithium, diisopropenylbenzenelithium. Aromatic hydrocarbon lithium such as alkyl lithium such as butyl lithium and a reaction product such as divinylbenzene; polynuclear hydrocarbon lithium such as lithium naphthalene; amino lithium and tributyl tin lithium. In addition to this polymerization initiator, an ether compound, a tertiary amine, or the like can be used as a styrene randomizing agent at the time of copolymerization and as a regulator of the microstructure of the butadiene unit in the polymer, if necessary. . Examples of the ether compound or tertiary amine include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether,
Triethylamine, pyridine, N-methylmorpholine,
N, N, N ', N'-tetramethylethylenediamine,
Examples include dipiperidinoethane and the like. Further, activators such as potassium dodecylbenzenesulfonate, potassium linoleate, potassium benzoate, potassium phthalate, and potassium tetradecylbenzenesulfonate can be used. Examples of the polymerization solvent include n-hexane,
Cyclohexane, heptane, benzene and the like can be used. As the polymerization method, either a batch polymerization method or a continuous polymerization method can be used. As the polymerization temperature,
Usually, it can be appropriately selected from the range of 0 ° C to 130 ° C, preferably 10 ° C to 100 ° C, and the polymerization time is usually 5 minutes to 24 hours, preferably 10 minutes to 10 hours. The monomer concentration in the polymerization solvent (total amount of monomers / (total amount of monomers + polymerization solvent)) is usually 5 to 50% by weight, and preferably selected from the range of 10 to 35% by weight. You can do it. When producing a styrene-butadiene copolymer, in order to prevent deactivation of the lithium catalyst, halogen compounds, oxygen, water, carbon dioxide gas and other deactivating compounds are mixed into the polymerization system. It is preferable to prevent this as much as possible.

(A) Characteristics relating to styrene content The styrene content of the styrene-butadiene copolymer used in the present invention is 5 to 45% by weight (characteristic (a)), preferably 15 to 45% by weight (characteristic (a) ')). If it is less than 5% by weight, abrasion resistance becomes insufficient, and if it exceeds 45% by weight, hysteresis loss in the range of 50 to 80 ° C (concept indicating fuel efficiency that correlates with energy loss (tan δ at 60 ° C)). Grows larger. This styrene content can be adjusted by changing the compounding ratio of styrene and butadiene when preparing the copolymer.

(B) 1, of the microstructure of the butadiene part
Properties Concerning 2-Bond Content The 1,2-bond content of the microstructure of the butadiene portion of the styrene-butadiene copolymer used in the present invention is 20.
-80% (characteristic (b)), preferably 25-70%
(Characteristic (b ′)), more preferably 30 to 70% (Characteristic (b ″)). When it is less than 20%, wet skid resistance (wet grip property) is more than 80%. The abrasion resistance becomes insufficient.The 1,2-bond content of this microstructure can be adjusted by adding a polar compound such as an ether compound or a tertiary amine as the microstructure modifier.

(C) Characteristics relating to glass transition temperature The glass transition temperature of the styrene-butadiene copolymer used in the present invention is -55 ° C to -20 ° C (characteristic (c)),
It is preferably −45 ° C. to −30 ° C. (characteristic (c ′)). If it is lower than −55 ° C., wet skid resistance (wet grip property) becomes insufficient, and if it exceeds −20 ° C., fuel efficiency becomes insufficient. This glass transition temperature can be adjusted by the styrene content and the 1,2-bond (vinyl) content of the microstructure of the butadiene portion. here,
The glass transition temperature and the styrene content and the microstructure of the butadiene portion have a relationship that the glass transition temperature also increases as the 1,2-bond (vinyl) content of the styrene content and the microstructure of the butadiene portion increases. Specifically, generally, when the styrene content is increased by 1% by weight, the glass transition temperature is increased by about 1 ° C, and when the 1,2-bond (vinyl) content is increased by 2%, the glass transition temperature is increased by about 1 ° C. As the adjusting method, in the case of styrene content, for example, a method of controlling the charged amount of styrene during polymerization can be mentioned. In the case of 1,2-bond (vinyl) content, for example, the above ether compound during polymerization can be mentioned. And a method of controlling the addition amount of a polar compound such as a tertiary amine (the 1,2-bond (vinyl) content increases as the addition amount of the polar compound increases). Incidentally. This polar compound also serves as a styrene randomizer.

(D) Characteristic Concerning Content Ratio of Single Chain and Long Chain in Styrene Unit The content ratio of single chain and long chain in the styrene unit of the styrene-butadiene copolymer used in the present invention is as follows. 1 single chain is 40 of fully bonded styrene
The styrene long chain in which 8% by weight or more and 8 or more by weight is 10% by weight or less (characteristic (d)) of the total bound styrene,
Preferably, one single chain is 40 to 80% by weight and the long chain is 5% by weight or less (characteristic (d ')). 1 single chain is less than 40% by weight of the total bound styrene, or 8 or more continuous styrene chains are 1% of the total bound styrene.
If it exceeds 0% by weight, low rolling resistance is insufficient. The content ratio of the single chain and the long chain in the styrene unit is, for example, 1) a method of controlling the polymerization temperature, 2)
It can be adjusted by, for example, a method of continuously introducing butadiene. That is, the polymerization (reaction) rate of styrene and butadiene when using a lithium-based initiator is different, and the polymerization rate is affected by the polymerization temperature and the monomer concentration. In the latter half of the high polymerization, a large amount of styrene reacts due to the influence of the temperature and a high concentration of the styrene monomer, so that a large number of long chain of styrene is generated and the content ratio of the long chain increases. Therefore, as a method for reducing the long chain of styrene to make the content ratio of the single chain and the long chain in an appropriate styrene unit, as described above, 1) the polymerization temperature,
By controlling when the reaction rates of styrene and butadiene are the same, or 2) by starting the reaction with the amount of butadiene charged before the reaction reduced, the amount of styrene taken up at the initial stage of polymerization was increased, and then the amount was reduced. The styrene chain length can be adjusted so as to maintain an appropriate styrene chain length (hold an appropriate content ratio of single chain or long chain) by a method of continuously introducing butadiene.

(E) Properties relating to modification of polymer terminal with polyfunctional coupling agent The styrene-butadiene copolymer used in the present invention is
If necessary, a branched structure may be introduced.
Examples of the copolymer having a branched structure include 1)
Examples thereof include those in which the polymer ends are modified with one or more polyfunctional coupling agents (characteristic (e)), and 2) those polymerized in the presence of a small amount of branching agent.
As a specific method for introducing such a branched structure,
When modified with the polyfunctional coupling agent of 1),
An active polymer having a lithium active terminal obtained by a batch polymerization method or a continuous polymerization method is used as a halogen-containing silicon compound such as silicon tetrachloride, an alkoxysilane compound, an alkoxysilane sulfide compound, a polyepoxy compound, a urea compound, an amide compound, an imide. There may be mentioned a method of reacting with one or more polyfunctional coupling agents selected from the group consisting of compounds, thiocarbonyl compounds, lactam compounds, ester compounds and ketone compounds. Among such polyfunctional coupling agents, halogen-containing silicon compounds such as silicon tetrachloride, alkoxysilane compounds, and alkoxysilane sulfide compounds are preferable because of low cost and stability of reaction. When the polymerization is carried out in the presence of a small amount of the branching agent of 2), a method of carrying out the polymerization in the presence of a small amount of the branching agent such as divinylbenzene can be mentioned. When a branched structure is introduced into the copolymer as described above,
Workability is improved because the entanglement of the polymers is easily released (compounding Mooney viscosity (ML _{1 + 4} , 100 ° C.) is small), but if the amount introduced is too large, gelation occurs and workability becomes insufficient. . Therefore, the amount introduced is sufficient to improve the workability, and the fuel economy,
It is preferable to set the amount within a range that does not impair the wear resistance and the low rolling resistance. For example, it is preferably 0 to 10%.

(F) Characteristics relating to molecular weight distribution The molecular weight distribution (weight average molecular weight / number average molecular weight) of the styrene-butadiene copolymer used in the present invention is as follows.
Although not particularly limited, 1.5 to 3.0 (characteristic (f)) is preferable, 1.5 to 2.5 (characteristic (f ′)) is further preferable, and 1.5 to 2.1 (characteristic ( f ″)) is most preferable. When it is less than 1.5, roll processability and extrudability may be insufficient, and when it exceeds 3.0, rolling property may be insufficient. The molecular weight distribution can be adjusted by adjusting the polymerization temperature and / or by using a chain transfer agent of an allene compound such as 1,2-butadiene and 1,2-isoprene.

(G) Properties Regarding Mooney Viscosity The oil-extended Mooney viscosity (OE-ML _{1 + 4} , 100 ° C.) of the styrene-butadiene copolymer used in the present invention is not particularly limited, but it is 20-100 (characteristic (g )) Is preferable, and 30-80 (characteristic (g ')) is more preferable. If it is less than 20, the breaking strength may be insufficient, and if it exceeds 100, roll workability and extrudability may be insufficient. The Mooney viscosity can be adjusted by controlling the molecular weight distribution and the weight average molecular weight.

(Ii) Compounding amount The styrene-butadiene copolymer used in the present invention is
It is 30 to 100% by weight, preferably 5 to 100% by weight, based on the total rubber components, as an oil that has been previously oil-extended using an extension oil.
It is contained in an amount of 0 to 100% by weight. If it is less than 30% by weight, high wet skid resistance and low rolling resistance will be insufficient.

Diene Rubber Other Than Styrene-Butadiene Copolymer In the present invention, in addition to the above styrene-butadiene copolymer, as the diene rubber which is the main component of the rubber component,
It is also possible to use a diene rubber other than the styrene-butadiene copolymer. Examples of such diene rubbers include natural rubber, polyisoprene rubber, and high cis 1,4 bond-polybutadiene rubber. The compounding amount of the diene rubber other than the styrene-butadiene copolymer is, for example, 0 to 70 in the rubber component.
It can be contained by weight%.

(2) Rubber component other than diene rubber As the rubber component used in the present invention, a rubber component other than the above diene rubber may be contained. Examples of rubber components other than this diene rubber include ethylene-propylene rubber, silicone rubber, and vinylidene fluoride rubber. As the compounding amount of the rubber component other than the diene rubber, for example, 0 to 30% by weight can be contained in all the rubber components.

2. Extension oil The styrene-butadiene copolymer used in the present invention needs to be oil-extended with extension oil in advance. By preliminarily oil-extending with the extender oil, the dispersibility of the extender oil in the rubber component and the filler to be described later can be improved as compared with a compounded rubber in which the oil is kneaded during compounding.

(1) Type The extender oil used in the present invention is not particularly limited as long as it is a normal extender oil for rubber, and examples thereof include naphthene-based, paraffin-based and aromatic oil-based oils. . Among them, aromatic oil type is preferable. Further, a naphthene-based or paraffin-based extender oil for rubber can be used together. When a rubber extending oil is used as the extending oil, the viscosity specific gravity constant shown in ASTM02501 is preferably 0.900 to 1.100, and more preferably 0.920 to 0.990. The method of oil extension is not particularly limited, and examples thereof include a method of adding an extender oil after completion of the polymerization, followed by desolvation and drying by a conventional method.

(2) Content Content of extender oil used for pre-oil-extending styrene-butadiene copolymer (oil extension amount) Extension amount used for pre-oil-extending the styrene-butadiene copolymer The oil content (oil extension) is 20 to 5 with respect to 100 parts by weight of the styrene-butadiene copolymer.
It is 0 part by weight, preferably 30 to 40 parts by weight. If the amount is less than 20 parts by weight, low rolling resistance is insufficient and 5
If it exceeds 0 parts by weight, the lower limit of the total amount of oil in the compounded rubber is limited to a high level, and the degree of freedom in compounding decreases.

Content of Total Extending Oil to All Rubber Components In the present invention, the extending oil may be blended separately in addition to the case of being used for oil extending the styrene-butadiene copolymer. For example, carbon masterbatch (CMB)
In the case of preparing the above, when a filler and an extender oil are further added to the oil-extended styrene-butadiene copolymer and kneading, the CMB is kneaded with other diene rubber, a compounding agent, etc. to obtain a tire. When manufacturing, etc. can be mentioned. In this case, the content of total extender oil (total amount for oil extension and compounding) is 10 to 50 with respect to 100 parts by weight of all rubber components.
Parts by weight. If it is less than 10 parts by weight, it is difficult to achieve both processability and fuel economy, and if it exceeds 50 parts by weight, fuel economy becomes insufficient.

3. Ingredients other than rubber component and extender oil In the rubber composition of the present invention, in addition to the rubber component and the extender oil for blending separately, components such as a filler, a vulcanizing agent, a vulcanization accelerator, and an antioxidant are added. Can be blended. (1) Filler Examples of the filler used in the present invention include carbon black, silica, clay, calcium carbonate, magnesium carbonate and the like. When carbon black is used, its content is preferably 2 to 100 parts by weight, more preferably 10 to 60 parts by weight, based on 100 parts by weight of the total rubber component. If it is less than 2 parts by weight, weather resistance and electric conductivity may be insufficient, and if it exceeds 100 parts by weight, impact resilience and low rolling resistance may be insufficient. When silica is used, its compounding amount is preferably 30 to 100 parts by weight with respect to 100 parts by weight of all rubber components,
More preferably, it is 35 to 70 parts by weight. If it is less than 30 parts by weight, wet skid properties may be insufficient, and if it exceeds 100 parts by weight, low rolling resistance may be insufficient. When silica is added as a filler or the like, it is preferable to add 5 to 20 parts by weight of a silane coupling agent to 100 parts by weight of silica.
Further, carbon black and silica may be used together.
In this case, the total amount of carbon black and silica is 30 to 100 parts by weight of all rubber components.
It is preferable to contain 100 parts by weight.

(2) Vulcanizing agent As the vulcanizing agent used in the present invention, for example, sulfur;
Peroxides such as di-t-butyl peroxide;
Examples thereof include sulfur-donating substances such as tetramethylthiuram disulfide. Of these, sulfur is preferred for its durability. The compounding amount of the vulcanizing agent is 1 for all rubber components.
0.5 to 5 parts by weight is preferable with respect to 00 parts by weight.

(3) Vulcanization accelerator Examples of the vulcanization accelerator used in the present invention include diphenylguanidine, N-tetra-butyl-2-benzothiazolesulfenamide, N-cyclohexyl-2-benzo. Thiazol sulfenamide etc. can be mentioned.
The compounding amount of the vulcanization accelerator is preferably 1 to 5 parts by weight with respect to 100 parts by weight of all rubber components.

(4) Anti-aging agent Examples of the anti-aging agent used in the present invention include N-
Examples thereof include phenyl-N'-isopropyl-p-phenylenediamine and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine. The amount of the antioxidant added is preferably 1 to 10 parts by weight with respect to 100 parts by weight of all rubber components.

(5) Other compounding agents Examples of other compounding agents used in the present invention include processing aids such as stearic acid, zinc white, and wax, and tackifiers.

(II) Method for Producing Rubber Composition The method for producing the rubber composition of the present invention is not particularly limited, but for example, a styrene-butadiene copolymer oil-extended in advance and, if necessary, used. Kneading separately with the blending components such as extender oil, filler, vulcanizing agent, vulcanization accelerator, and anti-aging agent by using a kneading machine for rubber such as internal mixer and open roll. I can list the method. A vulcanized rubber can be obtained by molding the obtained vulcanizable rubber composition of the present invention and then vulcanizing it at a temperature of 130 ° C to 200 ° C.

(III) Vulcanized Rubber Since the vulcanized rubber obtained from the rubber composition of the present invention exhibits extremely excellent high wet skid resistance and low rolling resistance, it can be used for tires, particularly high performance tires and tire treads. It can be suitably used for the purpose. It can also be used for other tire applications and general-purpose vulcanized rubber applications.
The industrial significance is extremely great.

[0036]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The measurement regarding each characteristic of the styrene-butadiene copolymer in the examples was based on the following methods. Styrene content (%) It was determined by preparing a calibration curve by the infrared absorption spectrum method. The 1,2-bond content (%) of the butadiene part was determined by an infrared absorption spectrum method (Morero method). Glass transition temperature (° C) Using a differential scanning calorimeter (DSC) manufactured by Seiko Denshi Kogyo Co., Ltd., measurement was performed at a temperature rising rate of 10 ° C / min, and the extrapolation start temperature was defined as the glass transition temperature. The weight average molecular weight, number average molecular weight, and molecular weight distribution were calculated in terms of polystyrene using GPC (gel permeation chromatograph). Styrene chain distribution (%) GPC (gel permeation chromatograph) of the decomposition product obtained by ozone cleavage of all double bonds of butadiene unit
(Polymer Society of Japan Proceedings Vol. 9, No. 9, p. 2,055). Mooney viscosity (OE-ML _{1 + 4} , 100 ° C.) Based on JIS K6300, it was measured at a temperature of 100 ° C. for 1 minute of preheating, 4 minutes of rotor operation time.

The measurement of the physical properties of the test pieces of the vulcanized rubber obtained by vulcanizing the rubber composition in the examples was based on the following methods. tan δ Tan δ at 60 ° C. was measured using a dynamic analyzer (RDA) manufactured by Rheometrics, Inc., USA under the conditions of dynamic strain of 1%, frequency of 10 Hz and 60 ° C. The smaller the value, the smaller the rolling resistance (low rolling resistance) and the better. The tan δ at 0 ° C. was measured using the same device under the conditions of dynamic strain 0.5%, frequency 10 Hz, and 0 ° C. The larger the value, the greater the wet skid property (high wet skid resistance) and the better. Lambourn abrasion index (abrasion resistance) It was measured at room temperature using a Lambourn abrasion tester. The index has a slip rate of 60%
Shows the amount of wear at. The larger this index, the better the abrasion resistance. Hardness: Measured at a temperature of 25 ° C. using a JIS hardness tester (A) type. The hardness was measured because, for example, if a tire tread or the like is too hard or too soft, there is a problem in practical use, and when the hardness is significantly different, the fuel consumption is determined by tan δ at 60 ° C and tan δ at 0 ° C. This makes it difficult to compare the wettability and wet grip.

[Examples 1 to 9 and Comparative Examples 1 to 10] Preparation of Copolymer and Oil Extension with Extending Oil Copolymers A to M shown in Tables 1 and 2 were prepared by the following method. Copolymers A and F 1 g of styrene and 175 g of 1,2-butadiene were placed in an autoclave reactor having an internal volume of 5 liters, which was replaced with nitrogen.
325 g of 1,3-butadiene containing 50 ppm, 2500 g of cyclohexane, 8.75 g of tetrahydrofuran,
And potassium dodecylbenzenesulfonate 0.068g
Was charged. After adjusting the temperature of the contents of the reaction vessel to 15 ° C., 3.91 mmol of n-butyllithium was added to initiate polymerization. After the polymerization conversion rate reached 100%, 3.51 mmol of methyltriphenoxysilane was added,
Copolymers A and F were obtained by carrying out a modification reaction for 15 minutes. Copolymer B 110 g of styrene, 385 g of 1,3-butadiene, 3025 g of cyclohexane, and 36 g of tetrahydrofuran were charged into an autoclave reaction vessel having an internal volume of 5 liters, which was sufficiently replaced with nitrogen. Set the temperature of the contents of the reaction vessel to 35
After adjusting to ℃, n-butyllithium 4.15mmo
1 was added to initiate the polymerization. After 5 minutes, 55 g of 1,3-butadiene was continuously introduced at a flow rate of 5 g / min,
After the polymerization conversion rate reached 100%, 0.5
By adding 5 mmol and performing a denaturation reaction for 15 minutes,
A copolymer B was obtained. Copolymer C In the preparation of copolymer B, the amount of styrene charged was 16
5 g, 1,3-butadiene charge amount to 332 g,
Copolymer C was prepared in the same manner as copolymer B except that the charged amount of tetrahydrofuran was changed to 9 g. Copolymer D In an autoclave reactor having an internal volume of 20 liters, which was sufficiently purged with nitrogen and equipped with a stirrer and a jacket, styrene 6 g / min and 1,3-butadiene 24 g / min containing 100 ppm of 1,2-butadiene were added. , Cyclohexane 1
50 g / min, tetrahydrofuran 4.17 g / min, n-
Butyllithium 0.196 mmol / min was continuously charged, and the temperature of the reaction vessel was controlled at 70 ° C.
At the outlet of the top of the first reaction vessel, silicon tetrachloride was added at a rate of 0.
Copolymer D was obtained by continuously adding it at 06 mmol / min, introducing this into the second reaction vessel connected to the above reaction vessel, and carrying out a modification reaction. Copolymer E In the preparation of Copolymer D, the charge amount of styrene is 1
Addition of n-butyllithium to 0.5 g / min, the charge amount of 1,3-butadiene containing 100 ppm of 1,2-butadiene to 19.5 g / min, and the charge amount of tetrahydrofuran to 0.97 g / min. 0.144 mmol
/ Min, and copolymer E was prepared in the same manner as copolymer D except that methyltriphenoxysilane was used at 0.052 g / min instead of silicon tetrachloride.
Was prepared. Copolymer G Copolymer B was prepared except that the amount of 1,3-butadiene charged was changed to 357 g and the amount of 1,3-butadiene continuously introduced was changed to 0 g. A copolymer G was prepared in the same manner as the preparation of the polymer B. Copolymer H A copolymer H was prepared in the same manner as the preparation of the copolymer B except that the addition amount of n-butyllithium was changed to 3.82 mmol in the preparation of the copolymer B. Copolymer I In the preparation of Copolymer D, 1,2-butadiene was added to 10
1,3-butadiene containing 130 ppm of 1,2-butadiene instead of 24 g / min of 1,3-butadiene containing 0 ppm
Copolymer I was prepared in the same manner as copolymer D except that butadiene was used at 24 g / min. Copolymer J In the preparation of copolymer B, the amount of styrene charged was 13
8 g, the amount of 1,3-butadiene charged to 358 g,
Copolymer J was prepared in the same manner as copolymer B except that the charged amount of tetrahydrofuran was changed to 7 g. Copolymer K In the preparation of copolymer B, the charged amount of styrene was adjusted to 28
The copolymer K was prepared in the same manner as the copolymer B except that the amount of 1,3-butadiene was changed to 468 g and the amount of tetrahydrofuran was changed to 135 g.
Was prepared. Copolymer L In the preparation of copolymer B, the amount of styrene charged was 24
8 g, the amount of 1,3-butadiene charged to 248 g,
Copolymer L was prepared in the same manner as copolymer B except that the charged amount of tetrahydrofuran was changed to 1 g. Copolymer M In the preparation of Copolymer B, the amount of styrene charged was 16
5 g, the amount of 1,3-butadiene charged to 330 g,
A copolymer M was prepared in the same manner as the copolymer B except that the charged amount of tetrahydrofuran was changed to 115 g. In addition, the copolymer F is a naphthene-based extender oil (manufactured by Fuji Kosan Co., Ltd .; FUCKOL FLEX # 1) after completion of the polymerization.
060 N) oil extension amount (extension oil content) 37.5 phr
(Parts per houndred parts
of rubber: parts by weight per 100 parts by weight of all rubber components) for oil extension. Copolymer H is good
Fragrance type extender oil (manufactured by Fuji Kosan Co., Ltd .; Fuccol Aromax)
# 3) was used for oil extension in the same manner with an oil extension of 15 phr.
Copolymer I was not oil-extended. Except for the copolymers F 1 , H and I, an aromatic extension oil (manufactured by Fuji Kosan Co., Ltd .; Fuccol Aromax # 3) was used to extend oil in the same manner with an oil extension of 37.5 phr . Of butadiene copolymers, copolymers A~F are styrene used in the present invention - - These of styrene obtained is butadiene copolymer, a copolymer G~M
Is a styrene-butadiene copolymer for comparison.

[0039]

[Table 1]

[0040]

[Table 2]

Preparation of rubber composition and vulcanized rubber Using the styrene-butadiene copolymers A to M obtained above, a Banbury mixer (BR type Banbury manufactured by Kobe Steel Ltd.) was used with the formulation shown in Table 3. And knead the compounding agent other than the vulcanizing system under the conditions of a starting temperature of 70 ° C, 60 rpm, and 3 minutes, and then a starting temperature of 70 ° C and 50 rp
The vulcanizing agent was kneaded under the condition of m for 1 minute to obtain a compound (rubber composition). After that, using a vulcanizing press, 160 ℃,
The mold was vulcanized under a vulcanization condition of 20 minutes to obtain a test piece. The results of measuring the physical properties of the vulcanized rubber using this test piece are shown in Tables 4 to 6.

[0042]

[Table 3] * 1) Rubber component refers to all rubber components blended such as styrene-butadiene copolymer, natural rubber, and high cis-butadiene rubber. In the case of an oil-extended polymer, only the polymer portion excluding oil is shown. The rubber compounding recipes are shown in Tables 4-5. * 2) Mitsubishi Kagaku Co., Ltd., Diamond Black N339 * 3) Nippon Silica Co., Ltd., Nipsil AQ * 4) Degussa Co., Si69 * 5) Fuji Kosan Co., Ltd., Fuccor Aromax # 3 In Table 3, compound No. The aromatic oil in Y is
It is shown that 37.5 is added to 100 parts of all rubber components.
However, the formulation of Example 9 in Table 5 described later (formulation
No. In the case of Y), the aromatic oil is all rubber component 1
Only 11.25 instead of 37.5 for 00
Be done. In the case of Example 9, the total amount of the extending oil is 10 in all the rubber components.
Although 37.5 is blended with respect to 0, Example 9
The copolymer F used for is a styrene-butadiene copolymer
Advance to the body 100 Nafute emissions-based extender oil 37.5
Since it was oil-extended using (in the case of Example 9, all rubber components
70 out of 100 styrene-butadiene copolymers
Therefore, naphthenic extender oil is used for 100 parts of all rubber components.
26.25), and in the end, Example 9
In Aromatic oil (11.25) and naphth
Extender oil as a total with Ten system extender oil (26.25)
Is blended in 37.5 with respect to 100 of all rubber components.
become. * 6) Ouchi Shinko Chemical Industry Co., Ltd., Nocrac 810NA * 7) Ouchi Shinko Chemical Industry Co., Ltd., Nox Cellar * 8) Ouchi Shinko Chemical Industry Co., Ltd., Nox Cellar D

[0043]

[Table 4] * 1) In the case of an oil-extended polymer, the amount including oil is displayed (the same applies to Tables 6 to 7). * 2) High cis butadiene rubber manufactured by Japan Synthetic Rubber Co., Ltd. (Table 6
~ 7 is the same).

[0044]

[Table 5] * 1) In the case of an oil-extended polymer, the amount including oil is displayed (the same applies to Tables 6 to 7). * 2) High cis butadiene rubber manufactured by Japan Synthetic Rubber Co., Ltd. (Table 6
~ 7 is the same).

[0045]

[Table 6]

[0046]

[Table 7]

As can be seen from Tables 1 to 7, Comparative Example 1,
In the case of the rubber compositions of 4 and 7 to 10, the properties (a) to (d) to be satisfied by the styrene-butadiene copolymer in the rubber composition of the present invention, that is, the styrene content (5 to 4).
5% by weight), 1,2-bond content of butadiene part (20
~ 80%), glass transition temperature (-55 ° C to -20 ° C),
The chain distribution of styrene (single chain: 40% by weight or more, long chain: 10% by weight or less) is not satisfied. That is, as shown in Tables 6 to 7, the copolymer G used in Comparative Examples 1 and 7 had a styrene chain distribution of single chain: 35.9% by weight and long chain: 13 as shown in Table 2. 0.1% by weight,
The copolymer J used in Comparative Example 4 shown in Table 6 has a glass transition temperature of −59 ° C. as shown in Table 2, and the copolymer K used in Comparative Example 8 shown in Table 7 is 2, the styrene content was 4% and the 1,2-bond content of the butadiene portion was 83%, and the copolymer L used in Comparative Example 9 shown in Table 7 was prepared as shown in Table 2. The styrene content was 47%, and the copolymer M used in Comparative Example 10 shown in Table 7 was
As shown in Table 1, the glass transition temperature is -16 ° C, which does not satisfy the characteristics (a) to (d) of the styrene-butadiene copolymer in the rubber composition of the present invention.

Similarly, the rubber compositions of Comparative Examples 2, 3, 5 and 6 do not meet the requirements to be satisfied by the rubber composition of the present invention. That is, in the rubber composition of the present invention, the content of the extending oil used for pre-oil-extending the styrene-butadiene copolymer is 10% by weight.
20 to 50 parts by weight with respect to 0 parts by weight, but Comparative Example 2
In this case, the copolymer H used in Comparative Example 2 shown in Table 6 has an oil extension amount (extended oil content) of 15 parts by weight, as shown in Table 2, and does not satisfy this requirement. Further, the rubber composition of the present invention contains 30 to 100% by weight of a styrene-butadiene copolymer having the above-mentioned characteristics, which has been oil-extended by using an extending oil, in the rubber component. In this case, the copolymer I used in Comparative Example 3 shown in Table 6 is
It is not pre-extended as shown in and does not meet this requirement. The molecular weight distribution is as wide as 4.9. In addition, the rubber composition of the present invention is obtained by preliminarily oil-extending a styrene-butadiene copolymer with an extending oil to obtain 30 parts in the rubber component.
However, as shown in Table 6, in Comparative Example 5, only 20% by weight of the styrene-butadiene copolymer rubber is contained in the rubber component, which does not satisfy this requirement. Further, in the rubber composition of the present invention, the content of total extending oil in the rubber component is 10 per 100 parts by weight of the total rubber component.
˜50 parts by weight, but in the case of Comparative Example 6, as shown in Table 7, the compounding No. Is Z, and as shown in Table 3, the content of the total extending oil is 60 parts by weight with respect to 100 parts by weight of all the rubber components, which does not satisfy this requirement.

As a result, Comparative Examples 1 to 10 shown in Tables 6 to 7
The vulcanized rubbers of Examples 1 to 9 are the vulcanized rubbers of Examples 1 to 9 shown in Tables 4 to 5, as can be seen from the balance of low rolling resistance, high wet skid resistance and abrasion resistance in each physical property of the vulcanized rubber. It is clear that it is inferior to.

[0050]

As described above, according to the present invention,
It has excellent low rolling resistance, high wet skid resistance, and wear resistance, and is particularly suitable for use in vulcanized rubber for high-performance tires and fuel-efficient tire treads, as well as general-purpose vulcanized rubber. It is possible to provide a rubber composition that is preferably used.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08K 5/541 C08K 5/54 (72) Inventor Fumio Tsutsumi 2-11-24 Tsukiji, Chuo-ku, Tokyo JSR Corporation ( 56) References JP-A 61-87737 (JP, A) JP-A 7-292161 (JP, A) JP-A 62-43439 (JP, A) JP-A 7-292162 (JP, A) JP Flat 3-252431 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 9/06

Claims (5)

(57) [Claims] 1. A rubber composition containing a diene rubber as a main component of a rubber component, wherein the following components (a) to (d) are used as one component of the diene rubber.
The styrene-butadiene copolymer having the characteristics shown in (1) is preliminarily oil-extended with an extension oil and contained in the rubber component in an amount of 30 to 100% by weight, and (a) the styrene content is 5 to 45% by weight. , (B) the 1,2-bond content of the microstructure of the butadiene portion is 20 to 80%, (c) the glass transition temperature is -55 ° C to -20 ° C, (d) the styrene unit. 1 single chain is 40% by weight or more of the total bound styrene, and 8 or more continuous styrene long chains are 10% by weight or less of the fully bound styrene,
In addition, the content (extending amount) of the extending oil used for pre-oil-extending the styrene-butadiene copolymer is 20 to 50 with respect to 100 parts by weight of the styrene-butadiene copolymer.
Furthermore, the content of total extender oil in all rubber components is 10 parts by weight.
A rubber composition comprising 10 to 50 parts by weight with respect to 0 parts by weight. 2. The rubber composition according to claim 1, wherein the styrene-butadiene copolymer further has the following characteristic (e). (E) the polymer terminal is a halogen-containing silicon compound,
Modified with one or more polyfunctional coupling agents selected from the group consisting of alkoxysilane compounds and alkoxysulfide compounds. 3. The rubber composition according to claim 1 or 2, wherein the styrene-butadiene copolymer further has the following characteristic (f). (F) The molecular weight distribution is 1.5 to 3.0. 4. The rubber composition as a filler is from 2 to 100 parts by weight of carbon black and / or from 30 to 100 parts by weight of all rubber components per 100 parts by weight of all rubber components.
4. Containing 100 parts by weight of silica, and in the case of containing silica, 5 to 20 parts by weight of a silane coupling agent is contained with respect to 100 parts by weight of silica. Rubber composition. 5. The rubber composition according to claim 1, wherein the rubber composition is used as a vulcanized rubber for a tire tread.