JPH051298B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a rubber composition with excellent rebound resilience and tensile strength of a vulcanizate. BACKGROUND ART In recent years, with the demand for lower fuel consumption for automobiles, conjugated diene polymers with excellent rebound resilience have been required as rubber materials for tires, especially tire treads and tire undertreads. . Conventionally, these conjugated diene polymers were
44-4996, U.S. Patent No. 3956232,
As described in JP-A No. 57-205414, a conjugated diene compound is polymerized using an organolithium initiator in a hydrocarbon solvent, or a conjugated diene compound and a vinyl aromatic compound are copolymerized. After that, it is obtained by reacting with a tin halide compound or an alkenyltin compound. Problems to be Solved by the Invention However, since the polymer terminals are composed of carbon-tin bonds, these obtained polymers are susceptible to acidic substances such as inorganic acids, organic carboxylic acids, Lewis acids, etc.
Due to chemical reactions with organic phosphorus compounds, organic sulfur compounds, etc., and hydrolysis reactions under strong acids or strong alkalis, the carbon-tin bonds at the polymer ends are easily broken, resulting in a decline in physical properties. Additives are restricted. In order to solve the problems of the prior art, the present inventors introduced a tertiary amino group at the end of a conjugated diene polymer, and further improved processability and tensile strength by combining a coupling agent such as a tin compound. A proposal was made to obtain a branched conjugated diene polymer with excellent strength and rebound properties (Japanese Patent Application Laid-open No. 59-38209), but the amino compound used here had no effect on improving the rebound properties of vulcanizates. Not enough. The present invention focused on the physical properties and processability improvement effects unique to amino groups, and as a result of intensive studies aimed at further improving the impact resilience and tensile strength of vulcanizates, we developed a conjugated diene having a specific aromatic amino group. The present invention was achieved by discovering that a rubber composition containing a (co)polymer can further improve tensile strength and impact resilience. Means for Solving the Problems The present invention involves solution polymerization of a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound in a hydrocarbon solvent using () a lithium-based initiator, and then An aromatic tertiary group is obtained by reacting an amine compound represented by the formula () and/or solution polymerization using an amine compound represented by the following general formula (). The rubber composition is characterized in that it contains 30 parts by weight or more of a conjugated diene polymer having a class amino group in 100 parts by weight of raw rubber. (In the general formula [] or [],
R and R' are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, an alkenyl group, n is an integer of 0 to 2, and X is -COOR,

[Formula] (R'' is an alkyl group having 1 to 20 carbon atoms), -CN, -CHO, -COCl, -COBr, (CH ₂ ) _n Cl,
(CH ₂ ) _n Br, (CH ₂ ) _n I, m is an integer from 0 to 20. ) The conjugated diene polymer of the present invention can be obtained by solution polymerizing a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound in a hydrocarbon solvent using a () lithium initiator, and then forming the conjugated diene polymer according to the general formula React the amine compound shown in [] or
() Obtained by solution polymerization using an amine compound (lithium-based initiator) represented by the above general formula []. Here, as the conjugated diene compound, 1,3-butadiene, isoprene, etc. are used, and among these, 1,3-butadiene is preferable. In addition, aromatic vinyl compounds include styrene,
Examples include vinyltoluene, p-methylstyrene, α-methylstyrene, and styrene is preferred. The amount of the aromatic vinyl compound to be used is 0 to 40% by weight, preferably 10 to 35% by weight, based on the total amount of monomers. If it exceeds 40% by weight, the rebound properties and tensile strength will be poor, which is not preferable. Furthermore, examples of hydrocarbon solvents include pentane, hexane, heptane, octane, methylcyclopentane, cyclohexane, benzene, xylene, and the like. The lithium-based initiators used in () include n-butyllithium, sec-butyllithium,
These are alkyl lithium and alkyl dilithium such as 1,4-dilithiobutane, and are used in an amount of 0.1 to 100 mg equivalent of lithium atom per 100 g of monomer. The same applies when the amine compound represented by the general formula [] in () is used as a lithium-based initiator. Examples of the amine compound represented by the general formula [] include methyl-o-dimethylaminobenzoate, α-dimethylaminophenyl acetonitrile, p-dimethylaminoacetophenone, and m-dimethylaminobenzaldehyde. It is not limited, and any amine compound that satisfies the above general formula [] may be used. In (), after solution polymerization, the lithium atom at the end of the resulting conjugated diene polymer is reacted with the functional group X of the amine compound of the general formula [], and the tertiary amino Groups bond together. The amine compound represented by the general formula [] is used in an amount of 0.1 to 3 equivalents per equivalent of the terminal lithium atom of the polymer, and the reaction temperature is 0 to 150°C. On the other hand, examples of the amine compound represented by the general formula [] include, but are not limited to, lithium benzylethylamide, lithium octyl phenylamide, lithium butyl phenyl amide, lithium benzyl methyl amide, etc. Any amine compound represented by the above general formula [] may be used. In (), since the amine compound represented by the general formula [] is solution polymerized using a lithium-based initiator, the amine compound derived from the amine compound is attached to the end of the resulting conjugated diene polymer via a carbon-nitrogen bond. A tertiary amino group will be bonded. In addition, in the case of solution polymerization using the amine compound represented by the general formula [] as a lithium-based initiator (that is, the polymerization method shown in () above), after the completion of polymerization,
R _o ′MX′ _4-o ′ (R is the same as the general formula [], [],
n' is an integer from 0 to 4, M is tin, silicon, germanium, lead, and X' is a halogen atom), specifically tin halides such as tin tetrachloride and methyl tin trichloride. Compounds, vinyltin compounds such as tetravinyltin and butyltrivinyltin, allyltin compounds such as tetraallyltin, diethyldiallyltin and tetra(2-octenyl)tin, tin compounds such as tetraphenyltin and tetrabenzyltin, tetrachloride Using coupling agents such as silicon, halogenated silicon compounds such as silicon tetrabromide, methyl silicon trichloride, and butyl silicon trichloride, alkoxy silicon compounds such as tetraphenoxy silicon and tetraethoxy silicon, and germanium halides such as germanium tetrachloride, Metal-
By forming a branched conjugated diene polymer consisting of conjugated diene bonds, it is possible to improve the cold flow of raw rubber. In this case, it is most preferable to use a branched conjugated diene polymer in which the bond of the branched moiety is a tin-conjugated diene bond. It can be obtained by adding 1 to 20 moles of a conjugated diene compound per 1 atomic equivalent of lithium in the amine compound (lithium-based initiator) and then adding the coupling agent. The polymerization reaction of () and () and the coupling reaction of () are carried out in the range of 0 to 120°C,
It may be carried out under isothermal conditions or under elevated temperature conditions. The polymerization method may be either a batch polymerization method or a continuous polymerization method. The microstructure of the conjugated diene moiety of the conjugated diene polymer includes tetrahydrofuran, diethyl ether, dimethoxybenzene, dimethoxyethane, ethylene glycol dibutyl ether, triethylamine, pyridine, N,N,N',N'-tetramethylethylenediamine, and dipylene. By adding ethers and tertiary amine compounds such as peridinoethane to the polymerization system of () or (), the vinyl content can be freely varied in the range of 10-95%. The above-mentioned conjugated diene polymer must be included in the composition of the present invention in an amount of 30% by weight or more per 100 parts by weight of the raw material rubber. It is not possible to obtain a rubber composition. Note that the microstructure of the diene part of the conjugated diene polymer applied to the composition of the present invention is not particularly limited, but the vinyl content of the butadiene part is 20 to 70%.
%, and a styrene-butadiene copolymer having a styrene content of 5 to 40% by weight is preferred because the wet skid resistance and tensile strength of the resulting rubber composition are improved. Also, the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn, molecular weight distribution) determined from the gel permeation chromatogram of the conjugated diene polymer.
is not particularly limited, but is preferably in the range of 1.7 to 5.0 in view of the balance between processability and physical properties. When the molecular weight distribution is within the above range, processability such as roll windability is improved, which is preferable. Further, the Mooney viscosity (ML ₁₊₄ , 100°C) of the conjugated diene polymer of the present invention is preferably in the range of 20 to 150. If it is less than 20, the tensile properties and rebound properties will deteriorate, which is undesirable. Exceeding this is not preferable due to poor workability. The rubber composition of the present invention has the conjugated diene polymer as an essential component, and contains natural rubber, high cis polyisoprene, emulsion polymerized styrene-butadiene copolymer, and no tertiary amino group at the polymer terminal. Bound styrene 10-40% by weight, vinyl content 10-80
% solution polymerized styrene-butadiene copolymer, nickel, cobalt, titanium, low cis polybutadiene obtained using a neodymium catalyst, and one or two types of ethylene-propylene-diene terpolymer.
It is obtained by blending with at least one selected rubber, and adding oil extenders such as aromatic process oil and naphthenic process oil, and various other compounding agents and vulcanizing agents as necessary. The rubber composition of the present invention can be used for tire applications such as tire treads, carcass, and sidewalls, belts, anti-vibration rubber, window frames, hoses, and industrial products. Effect The conjugated diene polymer used in the rubber composition of the present invention is produced by reacting the lithium atom at the end of the polymer with the functional group X in the amine compound represented by the general formula [] in () above. In addition, in (), by using an amine compound represented by the general formula [] as a lithium-based initiator, a specific tertiary amino group derived from the amine compound is introduced at the end of the resulting polymer. In this way, a rubber composition with excellent roll workability and excellent tensile strength and rebound properties of the vulcanizate is obtained. Examples The present invention will be described in more detail with reference to Examples below, but the invention is not limited to the Examples unless it goes beyond the gist of the present invention. In addition, various measurements in the examples were based on the following. Microstructure of butadiene moiety (vinyl content)
was determined by the infrared method (Morello method). The styrene content was measured using a calibration curve using an infrared method based on the absorption of phenyl groups at 699 cm ^-1 . Molecular weight distribution (Mw/Mn) is 200 manufactured by Waters.
Measured using type GPC. Column is STYRAGEL
-10 ⁶ , 10 ⁶ , 10 ⁵ , 10 ⁴ (4 feet x 4) were used. Tetrahydrofuran was used as a solvent. Mooney viscosity is determined by preheating for 1 minute, measuring for 4 minutes, and temperature.
Measured at 100℃. Tensile strength is measured according to JIS K6301. Wet skid resistance was measured at room temperature (25°C) using a Stanley skid tester, Comparative Example 4
is expressed as an index of 100, and the larger the value, the better. Repulsion was measured at 50°C to serve as an index of the tire's rolling friction resistance, and a Danlopt tripsomer was used as the measuring device. Processability was determined by rolling the kneaded product onto a 6-inch roll at 60°C (rating from 1 to 5,
The shape of the compound when extruded using a slit die rheometer (described in JP-A No. 57-45430), the extrusion workability as shown by the sharpness of the glossy corners (evaluation on a scale of 1 to 5,
(The higher the better) Examples 1 to 11, Comparative Examples 1 to 4 After charging cyclohexane, monomers, and tetrahydrofuran according to the recipe shown in Table 1 into a nitrogen-substituted reactor with an internal volume of 5 liters, () n-butyllithium , or () Add lithium benzylmethylamide and heat under insulation for 30~
The polymerization reaction was carried out at 90°C. After the polymerization conversion rate reaches 100%, in the case of (),
Further, a certain amount of an amine compound represented by the general formula [] was added in an amount of 1 equivalent per 1 atomic equivalent of lithium. Polymer F was prepared by continuously charging the solvent, monomer, and initiator to the composition shown in Table 1 using a reaction vessel with an internal volume of 10 liters, and carrying out the polymerization reaction at a temperature of 60°C. The amine compound is added at the outlet of the container. Further, Polymer L was continuously charged in the same manner as Polymer F using a reactor having an internal volume of 10 liters so as to have the charging composition shown in Table 1. In addition, as an initiator,
Lithium benzylmethylamide was used. Furthermore, Polymer M was polymerized using the same recipe as Polymer L, and methyl-o-dimethylaminobenzoate was added in the same amount as Polymer F after the polymerization was completed. Now, since the polymer used in this example has a large molecular weight, the tertiary polymer introduced at the end of the polymer
It is difficult to quantify amino groups (amino compounds). Therefore, the amount of lithium initiator was increased using the same recipe as for polymers A, D, and J in Table 1, and the polymerization reaction was carried out in the same manner as above to obtain (co)polymers A' and D′ and J′ were obtained, and after reprecipitation purification with methanol, the nitrogen content was measured by the Kjeldahl method (see Analytical Chemistry Handbook, September 20, 1981, Maruzen Publishing, p. 218), and it was found that A′ ;1.1%, D′;0.9
%, J': 1.0%, and it was confirmed that one tertiary amino group (amine compound) was bonded to each polymer chain. Microstructure of butadiene moiety (vinyl content),
The results of styrene content, molecular weight distribution, and Mooney viscosity are also shown in Table 2. The properties of the vulcanizate are as follows: The vulcanizate was kneaded and compounded using a 250 c.c. Brabender and a 6-inch roll according to the formulation shown in Table 3, and then vulcanized at 145°C for 30 minutes. Various measurements were carried out. The results are shown in Table 4. The SBR used in Table 4 is SBR #1500 manufactured by Japan Synthetic Rubber Co., Ltd. As is clear from Table 4, the present invention (Examples 1 to 11) is more effective than Comparative Examples 1 to 4.
It has excellent wet skid properties, rebound properties, processing properties, and tensile strength, making it an excellent tire material.

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[Table] Effects of the Invention The rubber composition of the present invention contains, as an essential component, a conjugated diene polymer in which a tertiary amino group derived from a specific amine compound is bonded to the polymer terminal. The vulcanizate thus obtained has high impact resilience and high tensile strength, and is particularly useful as a tire material.

Claims (1)

[Scope of Claims] 1 A conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound are subjected to solution polymerization in a hydrocarbon solvent using () a lithium-based initiator, and then and/or solution polymerization using an amine compound represented by the following general formula [], which has an aromatic tertiary amino group at the terminal part. A rubber composition comprising 30 parts by weight or more of a conjugated diene polymer per 100 parts by weight of raw rubber. (In the general formula [] or [],
R and R' are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, an alkenyl group, n is an integer of 0 to 2, and X is -COOR, C=
OR''(R'' is an alkyl group having 1 to 20 carbon atoms), -CN,
−CHO, −COCl, −COBr, (CH ₂ ) _n Cl, (CH ₂ ) _n
Br, (CH ₂ ) _n I,m is an integer from 0 to 20. 2. The rubber composition according to claim 1, wherein the conjugated diene polymer is a styrene-butadiene copolymer with a butadiene moiety having a vinyl content of 20 to 70% and a styrene content of 5 to 40% by weight.