JPH0621188B2 - Conjugated diene rubber composition for tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conjugated diene rubber composition for tires having improved vulcanized physical properties and processability, and more specifically, it is modified with a specific amide compound. The present invention relates to a conjugated diene rubber composition for tires, which is made of a conjugated diene polymer rubber, natural rubber or polyisoprene rubber.

[Prior Art] Conventionally, a conjugated diene rubber such as a natural rubber, a styrene-butadiene copolymer rubber or a polybutadiene rubber is used as a raw material rubber for each part of the tire such as a tread, a carcass, a side wall and a bead circumference of an automobile tire. In addition, a vulcanized rubber composition containing a rubber compounding agent such as carbon black and an extender oil for rubber is used. The rubber composition used for each part of these tires is required to have different performance according to the role of each part. For example, the tread portion requires physical properties such as wear resistance, braking performance, and heat resistance, as well as workability and workability such as roll processability, extrusion processability, adhesiveness, and adhesiveness when manufacturing tires. It is important from the industrial viewpoint, and performance in terms of both physical properties and processability is required. In order to satisfy these requirements, the raw material rubber, carbon black, vulcanizing agent and vulcanization accelerator, and other rubber chemicals used in the rubber composition for tires of various applications are various types and amounts according to their respective applications. It is used in a different formulation. Regarding the raw material rubber, styrene-butadiene rubber, polybutadiene rubber, butyl rubber, polychloroprene rubber, etc. are used as natural rubber or synthetic rubber, but in many cases, these are two types in order to satisfy the required performance. It is used by blending the above.

In particular, in recent years, in terms of performance, automobile tires are required to reduce rolling resistance from the standpoint of energy saving, and to improve steering stability and braking performance on wet roads from the viewpoint of safety. Has been required to improve productivity by improving workability.

To meet these demands for improvement, for example, as a method for improving the balance between rolling resistance and wet skid resistance (braking performance on wet road surface) of a tire tread polymer, JP-A-54-62248 discloses that the styrene content is 20
Styrene with a relatively large amount of vinyl bonds in the butadiene part at -40% and a glass transition temperature (Tg) of -50 ° C or higher
A method using a butadiene copolymer is disclosed in JP-A-57-73030.
JP-A No. 2003-242242 proposes a method of using a styrene-butadiene copolymer having a styrene content of 3 to 30%, a vinyl bond content of a butadiene portion of 60 to 95%, and branched with a specific metal compound. However, in these methods,
Since the polymer used is a polymer with a relatively high molecular weight or a narrow molecular weight distribution, the flow characteristics of the compound are often poor and the processability is often deteriorated. When added or blended with other rubber such as natural rubber, there is a problem that the physical properties are largely deteriorated, and it is difficult for these polymers to maintain the targeted performance characteristics.

Further, as a method for improving the workability while improving the rolling resistance and wet skid resistance balance of the polymer for tire tread, JP 58-162605 A discloses.
A method of using a branched styrene-butadiene copolymer having a wide molecular weight distribution and bound by tin is disclosed in Japanese Patent Application Laid-Open No.
59-45338 discloses a method of using a branched styrene-butadiene copolymer obtained by using tin and a bond other than tin in combination.

[Problems to be Solved by the Invention] However, when the polymers of these techniques are used,
Although it is possible to improve the processability to some extent, there is a problem that when it is used by blending with other polymers, characteristic deterioration of physical properties is observed. In the case of trying to improve, it was the actual situation that the initial performance could not be fully exhibited.

The present invention has been made in view of the above points, and in particular, a tire is manufactured while retaining the characteristics of physical properties such as impact resilience, heat resistance, wear resistance, wet skid resistance, and mechanical strength. It is an object of the present invention to provide a rubber composition for a tire, which has improved processability in carrying out.

[Means and Actions for Solving Problems] The present invention has been made through intensive studies on a conjugated diene polymer having a functional group bonded to a polymer chain and a composition thereof, and as a result, an active polymer having a lithium terminal has been obtained. And a conjugated diene-based copolymer obtained by the reaction of a specific amide compound having a cyclic structure with at least one rubber-like polymer selected from natural rubber or polyisoprene-based rubber. The vulcanized rubber composition described above has excellent impact resilience and heat resistance compared to conventional vulcanized rubber compositions using only raw rubber, and balances these with abrasion resistance and wet skid resistance. Is good,
It was made by finding that the unvulcanized compound has excellent processability.

That is, in the present invention, 30 to 90% by weight of the raw rubber [I] is (a) at least one conjugated diene compound or a conjugated diene compound and vinyl aroma using an organic lithium compound as a polymerization initiator in a hydrocarbon solvent. A polymer having an active lithium terminal obtained by polymerizing a group compound, (Wherein R ₁ represents a C _{1 to} C ₆ alkali group, a cycloalkyl group or an alkoxyalkyl group, Y represents an oxygen atom or a sulfur atom, and n represents an integer of 3 to 4) or In the above general formula One or more C ₁ ~ of in polymethylene Hisage hydrogen atoms represented
The polymer obtained by reacting an amide compound substituted with an alkyl group of C ₆ and having not reacted with the amide compound represented by the above general formula is less than 5% by weight, (b) Mooney viscosity (ML _{1+ 4} , 100 ° C) is 30 to 150 (c) A conjugated diene polymer having a glass transition temperature (Tg) of -100 to -20 ° C. [II] 10 to 70% by weight of raw rubber is natural rubber Or cis
-1.4 one or more selected from polyisoprene rubber having a bonding amount of 90% or more, and the weight average glass transition temperature of the raw material rubber of [III] and [I] and the raw material rubber of [II] is -95 to- The present invention relates to a conjugated diene rubber composition for tires, which has a temperature of 40 ° C.

The rubber composition for a tire of the present invention has impact resilience, heat resistance,
A conjugated diene rubber composition for tires having improved workability while maintaining physical properties required for tire rubber compositions such as wear resistance, wet / skid resistance, and mechanical strength, including tire treads. Under tread, carcass,
A rubber composition suitable for various parts of a tire such as sidewalls and beads.

The present invention will be described in detail below.

The displacement conjugated diene-based polymer having a specific functional group used as a part of the raw material rubber of the composition of the present invention, the activated conjugated diene-based polymer having a lithium terminal and a specific hydrocarbon group at the nitrogen atom Combined general formula (Wherein R ₁ represents a C _{1 to} C ₆ alkali group, a cycloalkyl group or an alkoxyalkyl group, Y represents an oxygen atom or a sulfur atom, and n represents an integer of 3 to 4) or In the above general formula One or more C ₁ ~ of in polymethylene Hisage hydrogen atoms represented
It is important that it consists of reaction with an amide compound having a structure substituted with a C ₆ alkyl group. This has a very important meaning in achieving the present invention. Normal,
In a stoichiometric reaction of a conjugated diene polymer that bonds an amide compound having an acyclic structure and a lithium atom, the bond between the carbonyl group and the amino group is cleaved as described in JP-B-42-24174. However, an amino group cannot be effectively introduced into a conjugated diene polymer. Further, when this reaction product is hydrolyzed, it becomes a secondary amino that deactivates the catalyst, so this reaction is not preferable in practice.

On the other hand, in a stoichiometric reaction of a amide compound having a cyclic structure used in the present invention and a conjugated diene-based polymer that binds a lithium atom in a hydrocarbon solvent, the conjugated diene can be reacted without releasing the secondary amine. A functional group such as an amino group can be reliably introduced into the polymer. When the conjugated diene polymer thus obtained is compounded, mixed and vulcanized with a compounding agent such as carbon black or process oil, the vulcanized product exhibits excellent impact resilience and heat resistance.

The conjugated diene polymer having an active lithium terminal to be reacted with the above specific amide compound is one kind selected from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, etc., using an organic lithium compound as a polymerization initiator. Or a conjugated diene compound or more thereof, or obtained by polymerizing or copolymerizing the conjugated diene compound with a vinyl aromatic compound selected from styrene, α-methylstyrene, p-methylstyrene and the like in a hydrocarbon solvent. After the polymerization reaction is substantially completed, it is subjected to a reaction with the specific amide compound.

Mooney viscosity (ML _{1 +} 4,1
(00 ° C.) is in the range of 30 to 150, and when the Mooney viscosity is less than 30, the final vulcanized rubber composition has poor physical properties such as impact resilience and heat resistance, while when the Mooney viscosity exceeds 150, the viscosity is It becomes extremely high, the dispersion of the compounding agent such as carbon black is deteriorated, and the abrasion resistance is deteriorated, so that the target performance cannot be obtained.

The glass transition temperature (Tg) of the modified conjugated diene polymer is -1.
It is in the range of 00 to -20 ° C. The glass transition temperature of the modified conjugated diene polymer is measured by DSC (Differential Thermal Scanning Meter) and changes depending on the conjugated diene compound of the constituent monomers, the type of vinyl aromatic compound and the bonding mode and composition of the conjugated diene compound. Can be made.

The above glass transition temperature range is a range in which the obtained rubber composition for tires is necessary for maintaining impact resilience, heat resistance, abrasion resistance strength, tensile strength, and low temperature characteristics, and other than the above range. Then one of the performance problems occurs.

When the modified conjugated diene polymer is a copolymer of a conjugated diene compound and a vinyl aromatic compound, the content of the vinyl aromatic compound in the polymer is adjusted to be within the above glass transition temperature range. To be done. Examples of the polymer serving as the base of the modified conjugated diene polymer include polybutadiene, polyisoprene, isoprene-butadiene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, and styrene-isoprene-butadiene copolymer. Preferred are polybutadiene and styrene-butadiene copolymer. In this case, the microstructure of the butadiene portion is preferably in the range of 10 to 85%, and the styrene content is preferably in the range of 0 to 50% by weight.

The basic performance of the above conjugated diene-based polymer varies greatly depending on the amount of vinyl bonds in the butadiene portion, the content of styrene, and the chain state of molecules, but these amounts depend on the application and blend in which the rubber composition is used. It is possible to set various values in relation to the type and amount of other rubbery polymer to be used. In the case of styrene-butadiene copolymer, the chain distribution of styrene (analysis by gel permeation chromatograph (GPC) of the decomposition product obtained by ozone cleavage of all double bonds of the butadiene unit) No. 9, p. 2055)), in order to improve impact resilience and heat resistance, a single chain of styrene is 40% by weight of the styrene content.
As described above, the styrene long chain in which 8 or more styrene moths are connected is preferably 5% by weight or less of the styrene content. The styrene composition distribution of the copolymer may be uniform or nonuniform in the molecular chain, but it is not preferable to form a large amount of block styrene.

Since the modified conjugated diene copolymer of the present invention has a molecular weight distribution ( _w / _n ) measured by GPC of 1.2 to 3.5, it shows a relatively good balance between physical properties and processability. Is preferred.

Regarding the shape of the molecular weight distribution, it may be monomodal or may have bimodal or more bimodal GPC chromatographic peaks.

A polymer having an active lithium terminal, which is a precursor of a modified conjugated diene polymer, can be obtained by the method described below.

n-hexane, cyclohexane, in an inert hydrocarbon solvent such as benzene, using a lithium-based compound such as n-butyllithium, sec-butyllithium as an initiator, to polymerize the conjugated diene compound or to conjugate diene compound Copolymerization of vinyl aromatic compound and vinyl aromatic compound gives a polymer with active lithium terminals. The microstructure of the conjugated diene part of the polymer, vinyl aromatic compound content and composition distribution, molecular weight distribution of the polymer. It is possible to adopt various methods in order to make the structure of the polymer such as For example, as a polar compound in the polymerization system, for example, diethyl ether, tetrahydrofuran,
By adding ethers such as ethylene glycol diethyl ether and triethylamine, amines such as tetramethylethylenediamine, it is possible to control the microstructure of the conjugated diene portion of the polymer and the composition distribution of the vinyl aromatic compound, and also By devising the method of adding monomers having different copolymerization reactivity into the polymerization system, the composition distribution can be controlled so that the vinyl aromatic compound can be uniformly present.

The polymerization and copolymerization reactions are usually carried out at a reaction temperature of 0 to 150 ° C., but conditions under which the active lithium terminal is deactivated and conditions under which a gel is formed by crosslinking are not preferred. The polymerization reaction can be carried out by a batch polymerization method, a continuous polymerization method or a combination thereof.

Next, in the present invention, the amide compound used to react with the polymer having an active lithium terminal to give a modified polymer containing a functional group is a compound having the structure of the above general formula, examples of which are shown below. As 1-cyclohexyl-2
-Pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-
Pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-
Pyrrolidone, 1,5-dimethyl-2-pyrrolidone, 1-methoxyethyl-2-pyrrolidone, 1-methyl-2-piperidone, 1,4-
Examples include dimethyl-2-piperidone, 1-isopropyl-2-piperidone, 1-isopropyl-5,5-dimethyl-2-piperidone, 1-methyl-2-pyrrolidone, 1-methyl-2-
Piperidone is preferred and 1-methyl-2-pyrrolidone is particularly preferred.

The specific amide compound used in the present invention reacts almost quantitatively when brought into contact with a polymer having an active lithium terminal, and the reaction condition is usually selected from the range of 25 to 150 ° C. and the reaction time of 1 second to 3 hours. To be done. The reaction proceeds almost stoichiometrically.

In the present invention, it is necessary that the amount of the polymer not modified with the functional group is less than 5% by weight based on all polymer molecules.

The modified conjugated diene-based polymer obtained in the reaction solvent by the above-mentioned production method, after a predetermined reaction, after adding an antioxidant such as 2,6-di-tert-butyl-p-cresol, is formed. Post-treatment such as polymer separation and washing / drying can be performed to obtain the desired polymer. It is also possible to add a paraffin-based, naphthene-based, aroatic-based, or other extender oil for rubber in a step before the above-mentioned post-treatment and use it as a masterbatch.

In the tire conjugated diene rubber composition of the present invention, the specific functional group-containing modified conjugated diene polymer is used in the range of 30 to 90% by weight, preferably 40 to 85% by weight of the raw rubber component. It

When the amount used exceeds 90% by weight, there is almost no difference from the modified donor diene polymer alone, while when it is less than 30% by weight, when the modified and non-modified ones are used for comparison,
There is virtually no difference in performance between the two.

Next, in the conjugated diene rubber composition for a tire of the present invention, the rubber-like polymer which constitutes the raw rubber together with the above [I] modified functional diene polymer is [II] natural rubber or cis-1,4 It is one or more polyisoprene rubber-like polymers selected from polyisoprene rubber having a binding amount of 90% or more.

These are 10 to 70% by weight of the raw rubber, preferably 15 to 60
Used in the range of wt%.

The natural rubber or the polyisoprene rubber having 90% or more of cis-1,4 bonds as the raw material rubber component of [II] is used in the conjugated diene rubber composition for a tire of the present invention, in heat resistance, tensile strength and flex resistance. It has the effect of making desirable physical properties such as vulcanized physical properties and roll processability, extrusion processability, green strength, and tack, and is used in tread applications, carcass applications, and sidewall applications for large tires and passenger car tires. The effect is great.

In the present invention, the weight average glass transition temperatures of the raw rubbers [I] and [II] are in the range of -95 to -40 ° C.

In the present invention, the weight average glass transition temperature of the raw rubber is a value represented by the following formula.

Tgm = ΣWi × Tgi / ΣWi where Tgm: weight average glass transition temperature Tgi: glass transition temperature of i component (measured by DSc) Wi: weight fraction of i component The weight average glass transition temperature of the raw rubber is It is appropriately selected depending on the intended use of the rubber composition for tires. For example, the material rubber used for treads of snow tires and studless tires, where low temperature performance is important, preferably has a weight average glass transition temperature in the range of -95 to -70 ° C, while wet skid resistance and steering For raw rubber for treads of high-performance tires and racing tires where stability is important, it is preferable that the weight average glass transition temperature is in the range of -65 to -40 ° C, and for other passenger car tires and large tires. In the tire tread, it is preferably in the range of -90 to -50 ° C. Also, the raw rubber of the composition of each part of the tire other than the tread, depending on the intended use, -95 ~ -40 ℃
Selected from the range. The glass transition temperature of the raw rubber is a factor that greatly affects the performance of each part of the tire, and for example, in a tread, it is involved in rolling resistance performance, abrasion resistance, wet skid resistance, and the like. Further, when the weight average glass transition temperature of the raw rubber exceeds -40 ° C, the low temperature characteristics are deteriorated.

The conjugated diene rubber composition for a tire of the present invention is characterized in that a raw material rubber having a specific structure as described above is used in a specific composition. It is put into practical use by blending carbon black, extender oil for rubber, vulcanizing agent and other compounding chemicals for rubber which are usually used.

In addition to the above requirements [I], [II] and [III], the following [IV] and [V]: [IV] carbon black is added per 100 parts by weight of the raw rubber 30
〜120 parts by weight, [V] extender oil for rubber is 5-80 per 100 parts by weight of raw rubber
A composition satisfying the requirement of including parts by weight constitutes a preferred embodiment of the present invention.

In the conjugated diene rubber composition for tires of the present invention,
Carbon black is contained in an amount of 30 to 120 parts by weight, preferably 35 to 100 parts by weight, based on 100 parts by weight of the raw rubber. As the carbon black, it is preferable to use furnace black having a high reinforcing property, and particles having various particle sizes such as SAF, ISAF, HAF, FEF and SRF grades and various structures are used. The structure of carbon black is represented by analytical values such as iodine adsorption amount, DBP oil absorption amount, nitrogen specific surface area and the like, and the properties of the vulcanized rubber are changed by these, but in the tire conjugated diene rubber composition of the present invention, Has an iodine adsorption capacity of 30-
Carbon black with 200mg / g, DBP oil absorption 60 ~ 160cm ² / 100g and nitrogen specific surface area 30 ~ 15m ² / g may be used alone or in combination of two or more depending on the required performance. preferable. If the amount of carbon black is less than 30 parts by weight per 100 parts by weight of the raw rubber, the reinforcing effect is small and the tensile strength and the like are not sufficient, while if it exceeds 120 parts by weight, impact resilience,
The heat resistance is lowered, which is not preferable.

In the conjugated diene rubber composition for tires of the present invention,
The extender oil for rubber is contained in an amount of 5 to 80 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the raw rubber. As the extender oil for rubber, aromatic, naphthene, or paraffinic extender oil is used depending on the use of the rubber composition of the present invention. For tread applications such as studless tires and snow tires where low temperature performance is important, and for carcass applications where heat resistance is important, naphthene-based and paraffin-based rubber extender oils are used and steering stability is required. In terms of applications, it is widely used such as using a relatively large amount of aromatic type extender oil for rubber.

If the amount of the extending oil for rubber is less than 5 parts by weight, the effect of improving the dispersion of carbon black by the extending oil for rubber is difficult to be exerted.
If it exceeds 80 parts by weight, the tensile strength, abrasion resistance, heat resistance and the like are deteriorated, which is not preferable.

The vulcanizing agent used in the composition of the present invention is mainly composed of sulfur, and peroxides and sulfur donating substances can also be used. The vulcanizing agent is preferably used in the range of 0.05 to 5 parts by weight per 100 parts by weight of the raw rubber.

Further, in the composition of the present invention, various compounding chemicals for rubber are used if necessary. Compounding agents for these rubbers include vulcanization aids such as stearic acid and zinc white, vulcanization accelerators of various systems such as sulfenamide-based, thiuram-based, guanidine-based, amine-based and phenol-based antioxidants, There are various chemicals such as antiozonants, processing aids, tackifiers and the like, which are used in the range of 0.05 to 10 parts by weight per 100 parts by weight of the raw rubber according to the use of the composition of the present invention.

The composition of the present invention, each component described above is compounded and kneaded by an internal mixer of a known rubber kneading machine, an open roll or the like, and after being molded through a step such as extrusion, tread, each part of a tire such as a sidewall. Form and finally
It is vulcanized at a temperature of 130-200 ℃ for 10-60 minutes.

The conjugated diene rubber composition for a tire of the present invention has excellent impact resilience and heat resistance, and has improved balance with abrasion resistance and wet skid resistance as compared with compositions using conventional raw material rubber. And at the same time the processability is good, so there is a high degree of freedom in the formulation of the formulation, and in some cases,
By adjusting the type and amount of carbon black and extender oil for rubber, it has the same impact resilience or heat resistance as the rubber composition using the conventional raw material rubber, and has high wear resistance and wet skid resistance. It is also possible to improve the width.

The conjugated diene rubber composition for a tire of the present invention is particularly suitable for a tread for tires such as a fuel-efficient tire, an all-season tire, a high-performance tire, a studless tire, and a snow tire, and a sidewall and an undertread. It is also possible to use it for carcasses, beads, etc. by taking advantage of its excellent balance of physical properties and workability of vulcanized products.

[Examples] Examples and comparative examples will be described below. This illustrates the invention, not limiting its scope.

In the examples, the measurement of polymer structure and the physical properties of vulcanized products were performed according to the methods described below.

The Mooney viscosity is 10 using the L rotor in the usual way.
It was measured at 0 ° C.

The styrene content was 26 by UV absorption spectroscopy.
It was calculated from the absorption based on the phenyl group at 2 nm.

The vinyl bond content of the butadiene portion was determined by measuring the spectrum with an infrared spectrophotometer and calculating the microstructure by the Hampton method.

The glass transition temperature was measured by DSC using a DSC according to ASTM-D3417-75, and the extrapolated temperature (Taf) was defined as the glass transition temperature.

The tensile strength of the vulcanized product was measured according to JIS-K-6301.

For the impact resilience, use the Ryupke impact resilience device and use JIS-K-63
The measurement was performed according to 01 at 70 ° C.

For heat resistance, use a Goodrich flexometer,
Start temperature 50 ° C, load 26 lbs, displacement 5.71 mm, rotation speed
The measurement was performed under the condition of 1800 rpm, and the difference between the sample temperature after 20 minutes and the start temperature was used as an index of heat resistance.

Abrasion resistance was measured using a pico abrasion tester.

Wet skid resistance was measured with a device manufactured by the British Road Research Institute.

The processability was judged by the roll operability and extrusion processability of the compound. The roll processability was evaluated by using the 6-inch test roll and wrapping property of the compound, operability and the like. The evaluation standard is A, which has a good dusting condition and is easy to operate without sticking to the roll surface, and D, which is difficult to operate without bagging and winding around the roll, and has the lowest rank.
The middle order was B and C.

The extrusion processability was judged by the shape of the extrudate and the surface texture using a Brabender Plastograph equipped with a Garvey die extruder. The evaluation criteria are as follows: the best surface is A with smooth surface and good edge cut, and the lowest rank is D with rough surface, uneven extrusion and poor edge shape. In order.

The polymers shown in Tables 1 to 3 were used in Examples and Comparative Examples.

BR-A to BR-C and SBR-D to SBR-G shown in Table 1 are all BR (polybutadiene rubber) and SBR (styrene-butadiene rubber) knitted by a specific cyclic amide compound, and shown in Table 3. BR-a ~ BR-c, SBR-d ~ SBR-g are not modified
BR and SBR are samples for comparison.

These samples were prepared by the method shown below.

Sample BR-A uses cyclohexane as a solvent, butadiene concentration is 16%, and n-butyllithium is 0.05% per 100 g of butadiene.
0g, tetrahydrolane 0.05g per 100g butadiene
Continuously supplied from the lower part to the first reactor at a rate of 10 to 100 ° C., the polymer solution in which the polymerization reaction is completed is continuously taken out from the upper part of the reactor while keeping the temperature inside the reactor at 90 to 100 ° C. Two
Was fed to the reactor. The average residence time of the reaction solution in the first reactor was 60 minutes. The temperature of the second reactor is 90
C., 1 mol of active lithium at a concentration of 0.95 mol per mol of 1-methyl-2-pyrrolidone was added to 0.07 per 100 g of the polymer.
4 g of a cyclic amide compound was continuously supplied and reacted to introduce a functional group. 2,6-di--tert-butyl-p-cresol as a stabilizer was added to the polymer solution thus obtained at a rate of 0.5 g per 100 g of the polymer, and the solvent was removed by heating to obtain the polymer. It was

Sample BR-a was obtained by the same method as that of sample BR-A except that methanol was used instead of the cyclic amide compound.

Samples BR-B, SBR-E, and SBR-G were prepared by the same continuous polymerization method as that used to obtain sample BR-A, and reacted with a cyclic amide compound.
In the adjustment of each of these samples, the amount of vinyl compound in the butadiene part was controlled by increasing or decreasing the amount of tetrahydrofuran, which is a polar compound, the Mooney viscosity was controlled by the amount of n-butyllithium, and the styrene ratio was adjusted by the supply ratio of butadiene and styrene. The content was controlled. Sample BR
-B used 1-cyclohexyl-2-pyrrolidone as a cyclic amide compound.

Samples SBR-b, SBR-e, and SBR-g correspond to samples SBR-B, SBR-E, and SBR-G, respectively.
Methanol was used instead of the cyclic amide compound.

Sample BR-C was prepared by the batch polymerization method shown below using cyclohexane as a solvent, and 15% solution of 1,3-butadiene contained tetramethylethylenediamine 0.2 g per 100 g of 1,3-butadiene.
0.040 g / n-butyllithium per 100 g of 1,3-butadiene
g was added, the temperature inside the reactor was maintained at 30 to 35 ° C., and the reaction was performed for 120 minutes. After the completion of the polymerization reaction, 0.071 g of 1-methyl-2-piperidone was added to 100 g of the polymer, and the mixture was reacted for 10 minutes. In the polymerization solution thus obtained, as a stabilizer, 2,6-di-ter
t-Butyl-p-cresol was added at a rate of 0.5 g per 100 g of polymer, and the solvent was removed by heating.

Sample BR-c used methanol instead of the cyclic amide compound in the same way as BR-C was obtained.

Samples SBR-D and SBR-F are still in the same batch polymerization method as sample SB-C, but the amount and type of polar compounds are changed to adjust the amount of vinyl, and the styrene content is adjusted by the ratio of butadiene and styrene. The Mooney viscosity was adjusted by adjusting the amount of butyllithium, and 1-methyl-2-pyrrolidone was reacted as a cyclic amide compound to obtain a modified polymer.

Samples SBR-d and SBR-f are polymers containing no functional group in which methanol was used instead of 1-methyl-2-pyrrolidone.

Further, as the raw material rubber of [II], those shown in Table 2 were used.

Example 1 and Comparative Example 1 According to the formulation shown in Table 4, the rubber composition having the blending ratio shown in Table 5 was kneaded and mixed by a pressure kneader, and the roll processability and extrusion of the unvulcanized product obtained. The workability was evaluated. In addition, vulcanization was performed at 145 ° C. for an appropriate time, and the vulcanized physical properties were evaluated.

The results are shown in Table 5.

As is clear from Table 5, in the blend composition limited by the present invention, the composition using the polybutadiene modified with a functional group shows excellent processability, and the vulcanized physical properties have high impact resilience and heat resistance. Be done. On the other hand, a composition using unmodified polybutadiene is inferior in impact resilience and heat resistance.

Example 2, Comparative Example 2 Similar to the formulation of Table 4, a rubber composition having the composition shown in Table 6 was prepared in the same manner as in Example 1, and the workability and vulcanized physical properties were evaluated. The results are shown in Table 6.

As shown in Table 6, the composition of the present invention exhibits excellent impact resilience and heat resistance as compared with the composition for comparison.

Example 3, Comparative Example 3 The rubber composition shown in Table 8 was prepared in the same manner as in Example 1 with the compounding recipe shown in Table 7. The results are shown in Table 8.

As is clear from the results in Table 8, the composition of the present invention has good processability, and also has excellent impact resilience and heat resistance.
They have an improved balance of wet skid resistance and abrasion resistance.

Example 4, Comparative Example 4 The rubber composition shown in Table 10 was prepared in the same manner as in Example 1 according to the formulation shown in Table 9, and the workability and vulcanized physical properties were evaluated. The results are shown in Table 10.

From the results in Table 10, it is clear that the composition of the present invention has good processability and vulcanized product properties.

[Advantages of the Invention] The conjugated diene rubber composition for tires of the present invention comprises a modified conjugated diene polymer obtained by a reaction of a specific cyclic amide compound and a conjugated diene polymer having an active lithium terminal, A conjugated diene rubber composition for tires using an isoprene-based polymer as a raw material rubber, and an unvulcanized product having good processability, excellent impact resilience, heat resistance, wear resistance and wetness. Balance with skid resistance is improved as compared to conventional compositions, and is preferably used for tire parts such as tread, undertread, carcass, sidewalls and bead parts.
In addition, it can be utilized for other uses of vulcanized rubber by utilizing its performance, and its industrial significance is great.

Claims (1)

[Claims] 1. [I] 30 to 90% by weight of a raw rubber is (a) at least one conjugated diene compound or a conjugated diene compound and a vinyl aromatic compound using an organic lithium compound as a polymerization initiator in a hydrocarbon solvent. A polymer having an active lithium terminal obtained by polymerizing a compound, (Wherein R ₁ represents a C ₁ -C ₆ alkyl group, a cycloalkyl group or an alkoxyalkyl group, Y represents an oxygen atom or a sulfur atom, and N represents an integer of 3 to 4) or In the general formula (C
One or more of the hydrogen atoms of the polymethylene chain represented by H ₂ ) _n
An unreacted polymer obtained by reacting an amide compound substituted with a C _{1 to} C ₆ alkyl group and having the unreacted amide compound represented by the above general formula is less than 5% by weight, and (b) Mooney viscosity ( ML _{1 + 4} , 100 ° C) is 30 to 150 (c) A conjugated diene polymer having a glass transition temperature (Tg) of -100 to -20 ° C. [II] 10 to 70% by weight of raw rubber is , Natural rubber or cis
-1.4 one or more selected from polyisoprene rubber having a bonding amount of 90% or more, and the weight average glass transition temperature of the raw material rubber of [III] and [I] and the raw material rubber of [II] is -95 to- A conjugated diene rubber composition for tires, which is at 40 ° C.