JP3378313B2 - Rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excellent rubber composition which is well balanced in abrasion resistance, low rolling resistance (low hysteresis loss) and wet skid property without impairing fracture characteristics.

[0002]

2. Description of the Related Art In recent years, automobiles are required to have low fuel consumption and safety. Therefore, a rubber composition used for a tread portion of a tire has low rolling resistance (low hysteresis loss) and wear resistance. And wet skid properties are desired.

Therefore, in order to reduce the rolling resistance of the conventional rubber composition of the tread portion, attention has been paid to the properties of the polymer contained in the rubber composition, and as a polymer capable of providing a low rolling resistance, natural rubber and poly Isoprene rubber or polybutadiene rubber is used.

However, since rolling resistance and wet skid property are contradictory to each other, when a rubber composition containing these polymers is used, the rolling resistance can be reduced but the wet skid of the tire can be reduced. On the other hand, if the wet skid property is emphasized, the amount of the reinforcing agent such as carbon black and the plasticizer such as oil will be increased, and the rolling resistance of the rubber composition will be reduced. It has been difficult to achieve a good balance between rolling resistance and wet skid resistance, such as the failure to perform.

In order to balance the wear resistance, low rolling resistance and wet skid property of the rubber composition, the styrene-butadiene copolymer used in the rubber composition contains a bound styrene content or a butadiene moiety. Attempts have been made to blend polymers having different vinyl bond contents (JP-B-46-27069, JP-A-47-4).
2729, ibid. 47-13532, ibid. 47-17449,
55-60539, 56-163908, 57-
70137 and 57-55941), an increase in the content of bound styrene resulted in an improvement in wet skid property, but the rolling resistance could not be decreased at the same time.

Further, when the vinyl content of the butadiene portion in the styrene-butadiene copolymer used in the rubber raw material is increased, the wet skid property of the tire using this rubber composition is improved, but the breaking property is increased. ,
On the contrary, the abrasion resistance is lowered, which is not preferable. Therefore, in addition to the above, only by optimizing the bound styrene content, the microstructure of the butadiene portion, the composition distribution in these molecular chains, and the molecular weight distribution, it is possible to reduce fuel consumption in automobiles, that is, to reduce the rubber composition. It has been difficult to obtain a rubber composition suitable for a tire tread, which satisfies the required performances such as rolling resistance (low hysteresis loss property), breaking property, and wet skid property in good balance.

Further, as a polymer used in the rubber composition, a polymer having a significantly improved low hysteresis loss property is prepared by polymerizing an organolithium compound as an initiator in a hydrocarbon solvent, and a tin halide compound is used as a cap at the polymerization end. There are ringed polymers (JP-A-57-55912, etc.). This polymer is a polymer having very excellent physical properties, and is effectively used as a rubber composition for low rolling resistance and thus fuel-efficient tires.

Further, as a polymer used in a rubber composition, there is known a method for producing a styrene-butadiene copolymer having remarkably improved impact resilience (Japanese Patent Publication No. 4-433).
5). In this styrene-butadiene copolymer, at least 0.1 mol of benzophenone or thiobenzophenone having at least one amino group, alkylamino group or dialkylamino group in the molecular chain is introduced per mol of the rubber molecular chain. As a method for introducing the benzophenones and thiobenzophenones into the molecular chain, which is a copolymer, an alkali metal-based catalyst is used to polymerize a styrene-butadiene copolymer rubber, and the polymerization reaction is completed in a rubber solvent. A method of adding benzophenones (terminal modification method) and a method of adding an alkali metal to the rubber in a styrene-butadiene copolymer rubber solution and then adding the benzophenones are disclosed.

[0009]

However, the polymer obtained by the coupling reaction of the above-mentioned polymerization chain terminal lithium and the tin halide compound is very useful, but also has drawbacks. The drawback is that even if this tin halide compound is reacted in an equivalent amount with respect to the terminal lithium, it is 100% theoretically.
The reaction does not occur at the coupling efficiency of 60%, and the industrial efficiency remains at about 60%, and the coupling efficiency tends to become lower as the molecular weight of the polymer having the terminal lithium in the polymer chain increases. It is in. As described above, tin is not bound to all polymer terminals, and even if tin is bound, it is bound only to the terminal of the polymer, and tin cannot be introduced into the polymer other than the terminal. On the other hand, since the degree of reduction of hysteresis loss depends on the amount of tin in the polymer, the conventional method can obtain a polymer having a small hysteresis loss to some extent, but it is not always sufficient.

Further, at least 1 is added to the above rubber molecular chain.
Each of the disclosed methods also has a problem with respect to the method for producing a polymer having benzophenones or thiobenzophenones having one amino group, an alkylamino group, or a dialkylamino group introduced therein. That is, styrene and butadiene are copolymerized using an alkyl metal base catalyst, and in a rubber solution in which the polymerization reaction is completed,
In the terminal modification method in which a modifier such as benzophenone is added, it is difficult to introduce a large number of modifiers into the molecular chain because the living polymerization end is deactivated by the introduction of the modifier.
Moreover, in this terminal modification method, introduction into a molecular chain other than the terminal is basically impossible. On the other hand, a method in which styrene-butadiene copolymer rubber is dissolved in a solvent and an alkali metal is added, and then a modifier such as benzophenone is added, is also an undesirable side reaction such as gelation of a polymer when an alkali metal is added. However, there are drawbacks that it is easy to occur, cost is high, and practicality is poor.

The present invention overcomes the drawbacks or problems brought about by the above-mentioned known means and methods, has significantly low rolling resistance (hysteresis loss property), and
An object of the present invention is to provide a rubber composition for tires which is excellent in balance between abrasion resistance and wet skid property without impairing the fracture characteristics.

[0012]

A rubber composition according to claim 1 comprises a conjugated diene or a conjugated diene and a vinyl aromatic hydrocarbon in an hydrocarbon solvent using an organolithium compound as an initiator, the following general formula A and Number average molecular weight M obtained by copolymerizing with an organic nitrogen compound represented by the general formula B
100 parts by weight of a rubber raw material containing 30 parts by weight or more of a polymer in which n is 9 × 10 ⁴ to 80 × 10 ⁴ and 20% with respect to the rubber raw material
It is characterized by containing -100 parts by weight of a filler consisting only of carbon black and 0.1-5 parts by weight of a vulcanizing agent with respect to the rubber raw material.

[Chemical 3] Is a group bonded to the benzene ring, and X is ( CR ₆ R ₇ ) n
Or a saturated ring-forming part consisting of ( CR ₈ R ₉ ) m and NR ₁₀ or O, or a carbon-carbon single bond in the saturated ring-forming part. It represents an unsaturated ring forming part having at least a part of carbon-carbon double bond. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ ,
R ₁₀ is hydrogen or an aliphatic group having 1 to 30 carbon atoms, an alicyclic group,
It represents a group selected from each aromatic hydrocarbon group and may be the same or different. However, R ₄ , R ₅ and
R ₁₀ does not contain a hydrogen atom. Further, n represents an integer of 3 to 10 and m represents an integer of 2 to 9. ) In addition, the rubber composition according to claim 2 is present in a hydrocarbon solvent.
Conjugated with a lithium compound as an initiator
Represented by ene and vinyl aromatic hydrocarbons and the following general formula B
Obtained by copolymerizing with an organic nitrogen compound
A polymer having an average molecular weight Mn of 9 × 10 ⁴ to 80 × 10 ⁴ was added to 30
100 parts by weight of rubber raw material containing more than 1 part by weight,
20 to 100 parts by weight of carbon black,
0.1 to 5 parts by weight of a vulcanizing agent with respect to the rubber raw material
Is characterized by.

[Chemical 4] Is a group bonded to the benzene ring, and X is (CR ₆ R ₇ ) n
A saturated ring-forming moiety consisting of or (CR ₈ R ₉ ) m and
And a saturated ring-forming moiety consisting of NR ₁₀ or O, or
At least the carbon-carbon single bond in the saturated ring forming part.
Represents an unsaturated ring forming part with a part of carbon-carbon double bond
You R ₁ , R ₂ , R ₃ , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are water.
Elementary or C1-C30 aliphatic, alicyclic, aromatic
Represents a group selected from hydrocarbon groups, even if the same
It may be different. However, R ₁₀ does not include a hydrogen atom.
Yes. In addition, n represents an integer of 3 to 10 and m represents an integer of 2 to 9.
Wath. )

The rubber composition according to claim 3 is the rubber composition according to claim 1,
Alternatively, in claim 2 , the rubber raw material has a number average molecular weight of 9 × 1 obtained after the polymerization reaction substantially completed.
At least 1 selected from a silicon compound, a tin compound, an isocyanate group in the molecule, or a compound containing -CM-N <bond (M: S or O) in a polymer of 0 ⁴ to 80 × 10 ^4.
Polymer obtained by adding two compounds as modifiers
It is characterized by being a rubber raw material containing 0 or more parts.

The inventors of the present invention have earnestly studied by paying attention to the polymerization reaction by organolithium and the chemical structure of a functional monomer containing a polymerizable vinyl group, and as a result, the organic compound represented by the general formula A or B The nitrogen compound has excellent copolymerizability with, for example, butadiene and styrene, and the rubber obtained by kneading the obtained copolymer with carbon black as a part or all of the rubber raw material and blending a vulcanizing agent and the like. It has been found that the composition has an extremely low hysteresis loss property, and is well balanced in physical properties such as wear resistance and wet skid property without impairing the fracture property, and is an excellent rubber composition. The present invention has been completed.

That is, when random copolymerization of butadiene and styrene is carried out in a hydrocarbon solvent using butyllithium as an initiator and an ether compound, vinylbenzyldiethylamine is used in a molar ratio of 5 to 5 at the end of the polymerization chain. When a double molar amount is added, an average of 5 molecules of vinylbenzyldiethylamine is easily copolymerized in one chain of a random copolymer of butadiene and styrene, and the above-mentioned amino group-containing benzophenones are copolymerized with the butadiene-styrene copolymer. No problems and drawbacks of the introduction of amino group-containing benzophenones and the like, which are recognized in the publicly known method (Japanese Patent Publication No. 4-4335), were not found. Further, the vulcanized rubber obtained by vulcanizing the copolymer of the present invention thus obtained was remarkably recognized as having low hysteresis loss.
Furthermore, since the polymerization mechanism of the polymer of the present invention is anionic living polymerization, it is also possible to modify the polymerization chain ends by combining a polymerization chain terminal lithium and a modifier such as a tin halide compound. It was found that the decrease in hysteresis loss becomes even more remarkable.

The present invention will be described in detail below. The organolithium compound used as an initiator in the production of the polymer used in the rubber composition of the present invention includes n-butyllithium, ethyllithium, propyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, Examples include 1,4-dilithiobutane, alkyllithium such as a reaction product of butyllithium and divinylbenzene, alkylenedilithium, phenyllithium, stilbendilithium, lithium diisopropylamide, lithium piperidide, and the like. Preferred is n-butyllithium or sec-butyllithium. These organolithium initiators may be used alone or in combination of two or more. The amount of these organolithium compounds used can be used in the range of 0.1 to 30 mmol per 100 g of the monomer.

To obtain the polymer in the rubber composition of the present invention, the monomer used for the polymerization is a conjugated diene or a conjugated diene and a vinyl aromatic hydrocarbon, the conjugated diene having 4 to 12 carbon atoms per molecule. ,Preferably,
It is a conjugated diene hydrocarbon having from 4 to 8. For example,
1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, octadiene and the like can be mentioned. These may be used alone or in combination of two or more, and 1,3-butadiene is particularly preferable.

Examples of the vinyl aromatic hydrocarbon include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-butylstyrene, vinylnaphthalene and the like, and styrene is particularly preferable.

The organic nitrogen compound represented by the general formula A of the present invention, -CR ₁ = CR ₂ R ₃ is a group bonded to the benzene ring of the benzyl group, ortho, meta, to any of the para position Although it may be bonded, it is preferably bonded to the meta position or the para position. R ₁ , R ₂ , R ₃ and R ₄ and R ₅ bonded to the nitrogen atom are each selected from a hydrogen atom or an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 20 carbon atoms. And R ₄ and R ₅ do not contain hydrogen, although they may be the same or different. General formula A
Examples of the organic nitrogen compound represented by are vinylbenzyldimethylamine, vinylbenzyldiethylamine,
Examples thereof include vinylbenzyldipropylamine.

In the organic nitrogen compound represented by the general formula B of the present invention, -CR ₁ = CR ₂ R ₃ is the same as in the general formula A. Further, the part represented by X is a ring forming part which forms a ring with N, and is a saturated ring forming part consisting of ( CR ₆ R ₇ ) n, ( CR ₈ R ₉ ) m and N R ₁₀ or O Or the unsaturated ring forming part in which at least a part of the carbon-carbon single bond in the saturated ring forming part is a carbon-carbon double bond. R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are hydrogen or a group selected from aliphatic, alicyclic, and aromatic hydrocarbons having 1 to 10 carbon atoms, and the same or different. However, R ₁₀ does not contain hydrogen. Also, n is 3 to
10, m represents an integer of 2-9. Examples of the organic nitrogen compound represented by the general formula B include vinylbenzylpyrrolidine, vinylbenzylpiperidine, N-vinylbenzylazacycloheptane and the like.

The method for synthesizing the organic nitrogen compounds represented by the general formulas A and B (hereinafter abbreviated as compound monomer) is not particularly limited, but, for example, vinylbenzyl chloride and excess diethylamine, pyrrolidine, and morpholine. It is possible to employ a method in which a secondary amine such as the above is directly reacted in a solvent such as benzene or toluene, or in the absence of a solvent to synthesize it. The obtained compound is GC-MS
It confirmed by the analytical method and the 1H-NMR analytical method.

In the method for producing a polymer of the present invention, the amount of the compound monomer added is such that, in the case of copolymerization of the conjugated diene and the compound monomer, the amount of the conjugated diene is 75 to 99.95% by weight, preferably 90 to 99. 9% by weight, the amount of the compound monomer is 0.05 to 25% by weight, preferably 0.1 to 25% by weight.
It is 10% by weight. In the case of copolymerization of a conjugated diene, a vinyl aromatic hydrocarbon and a compound monomer, the amount of the conjugated diene in all the monomers used is 50 to 95% by weight, preferably 60 to 90% by weight. Hydrogen is 5 to 50% by weight, preferably 5 to 40% by weight, and compound monomer is 0.05 to 25% by weight, preferably 0.1 to 25% by weight.
It is 5% by weight. Excessive use of more than 25% by weight of the compound monomer is not preferable from the viewpoint of processability and vulcanization scorch property of rubber. The compound monomers may be used alone or in combination of two or more for polymerization.

Various methods can be adopted as a method for adding the compound monomer to the polymerization system. As an example, the compound monomer is added once at every stage of the polymerization chain growth from the start to the end of the polymerization. Even if added in
Alternatively, it may be added in a plurality of divided portions, or it may be mixed with the conjugated diene in advance, or with the conjugated diene and the vinyl aromatic hydrocarbon, and polymerized. As the copolymerization of the compound monomer, the compound monomer may be randomly copolymerized in the polymer chain or may be copolymerized in a block state.

The polymer in the present invention contains (1) a conjugated diene unit, or a conjugated diene unit and a vinyl aromatic hydrocarbon unit, and (2) a compound monomer unit. Therefore, examples of the obtained polymer include a conjugated diene / compound monomer copolymer, a conjugated diene / vinyl aromatic hydrocarbon / compound monomer copolymer, and the like.

With respect to the molecular weight of the polymer of the present invention, the number average molecular weight before or after addition of the modifier is 9 × 1.
0 ⁴ to 80 × 10 ⁴ , preferably 5 × 10 ^{4 to} 60 × 1
0 ⁴ , more preferably 10 × 10 ^{4 to} 35 × 10 ⁴ . If the number average molecular weight is less than 9 × 10 ⁴ , the effect of addition of the compound monomer cannot be sufficiently exerted, and 80
When it exceeds × 10 ⁴ , it is not preferable in terms of rubber properties and kneadability with carbon black. The molecular weight of the polymer of the present invention can be easily adjusted by the concentration of the organolithium initiator and the like.

In the production of the polymer of the present invention, after completion of the polymerization reaction, it is selected from a silicon compound, a tin compound, a compound containing an isocyanate group or -CM-N <bond (M: O or S) in the molecule. At least one compound selected from the above can be added as a modifier.

Examples of the silicon compound include silicon tetrachloride, chlorotriethylsilane, chlorotriphenylsilane, dichlorodimethylsilane and the like.

Examples of the tin compound include tin halides such as tin tetrachloride and tin tetrabromide, and organotin halides such as diethyldichlorotin, dibutyldichlorotin, tributyltin chloride, diphenyldichlorotin and triphenyltin chloride. Compounds.

Examples of the isocyanate group-containing compound include phenyl isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and dimer and trimer aromatic polyamines thereof. Isocyanate compounds can be mentioned.

Examples of the compound containing -CM-N <bond (M: O or S) include formamide, N, N-dimethylformamide, acetamide, N, N-diethylacetamide, aminoacetamide, N, N-dimethyl-.
N ', N'-dimethylaminoacetamide, N, N-dimethylaminoacetamide, N, N-dimethyl-N'-
Ethylaminoacetamide, acrylamide, N, N-
Dimethylacrylamide, N, N-dimethylmethacrylamide, nicotinamide, isonicotinamide, picolinic acid amide, N, N-dimethylisonicotinamide, succinic acid amide, phthalic acid amide, N, N, N ', N'-tetra Methylphthalic acid amide, oxamide, N, N, N
', N'-tetramethyloxamide, 1,2-cyclohexanedicarboximide, 2-furancarboxylic acid amide, N, N-dimethyl-2-furancarboxylic acid amide,
Amido compounds such as quinoline-2-carboxylic acid amide and N-ethyl-N-methyl-quinolinecarboxylic acid amide, succinimide, N-methylsuccinimide, maleimide, N
-Imide compounds such as methylmaleimide, phthalimide and N-methylphthalimide, ε-caprolactam, N-methyl-ε-caprolactam, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2-piperidone, N-methyl-2
-Lactam compounds such as piperidone, 2-quinolone, N-methyl-2-quinolone, urea, N, N-dimethylurea,
Urea compounds such as N, N-diethylurea, N, N, N ', N'-tetramethylurea, N, N-dimethyl-N', N'-diphenylurea, N, N'-dimethylethyleneurea, methyl carbamate, N, N -Carbamic acid derivatives such as methyl diethylcarbamate, isocyanuric acid,
Examples thereof include isocyanuric acid derivatives such as N, N ′, N ″ -trimethylisocyanuric acid and their corresponding thiocarbonyl-containing compounds, etc. The modifier is not particularly limited as long as it is a compound that reacts with the chain end of the polymer.

In the polymerization reaction system of the polymer of the present invention, in order to improve the polymerization activity and / or adjust the desired molecular structure such as molecular weight, microstructure, composition distribution (in the case of copolymer) depending on the use, The usual additives used for this purpose, such as ether compounds, Lewis bases of tertiary amine compounds, can be added. The amount of the ether compound and the tertiary amine compound used is 0.05 per mol of the organic lithium compound.
It is used in the range of up to 1000 mol.

The polymerization temperature is usually -20 to 150 ° C,
It is preferably 0 to 120 ° C.

As the rubber raw material of the rubber composition of the present invention, in practice, a blend of the above-mentioned polymer and natural rubber or other synthetic rubber is used. In the case of blending, it is necessary to contain the polymer in the rubber raw material in an amount of 30% by weight or more, preferably 40% by weight or more. For example, in a blend with natural rubber, when the polymer of the present invention is less than 30% by weight, wet skid property is deteriorated,
It is not preferable because the balance of properties required for the rubber composition is impaired.

Examples of the synthetic rubber used as a blend include cis-1,4-polyisoprene, styrene-butadiene copolymer, low cis-1,4-polybutadiene,
Examples thereof include high cis-1,4-polybutadiene, ethylene-propylene-diene copolymer, chloroprene, halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like.

The blending amount of carbon black in the present invention is 20 to 100 parts by weight based on the rubber raw material,
It is preferably 25 to 80 parts by weight. If it is less than 20 parts by weight, the vulcanized product has insufficient tensile strength and abrasion resistance, and if it exceeds 100 parts by weight, rolling resistance (hysteresis loss property) and the like are not preferable. The carbon black used is such a carbon black as HAF, ISAF, SAF, etc., and preferably the iodine adsorption amount (IA).
Is 60 mg / g or more, and dibutyl phthalate oil absorption (DBP) is 80 ml / 100 g or more.

Examples of the vulcanizing agent include sulfur, and the amount of these is 0.1 to 5 with respect to 100 parts by weight of the rubber raw material.
Parts by weight, preferably 0.5 to 2 parts by weight. If it is less than 0.1 part by weight, the tensile strength, abrasion resistance and hysteresis loss of the vulcanized rubber will decrease, and if it exceeds 5 parts by weight, rubber elasticity will be lost.

The process oil usable in the present invention includes:
For example, paraffin type, naphthene type, aromatic type and the like can be mentioned. An aromatic type is used for applications where importance is attached to tensile strength and wear resistance, and a naphthene type or paraffin type is used for applications where importance is attached to hysteresis loss and low temperature characteristics. The amount of use is 100 parts by weight of rubber raw material. 0
It is up to 100 parts by weight, and if it exceeds 100 parts by weight, the tensile strength and low hysteresis loss of the vulcanized rubber are significantly deteriorated.

The vulcanization accelerator which can be used in the present invention is not particularly limited, but preferably M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-). Examples thereof include thiazole-based vulcanization accelerators such as benzothiazylsulfenamide) and DPG (diphenylguanidine) such as DPG (diphenylguanidine). -5 parts by weight, preferably 0.2-3
Parts by weight.

In the present invention, in addition to these, antioxidants usually used in the rubber industry, fillers other than carbon black such as silica, calcium carbonate and titanium oxide, zinc oxide, stearic acid, antioxidants, Additives such as antiozonants may also be added.

The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll or an internal mixer. After molding, vulcanization is performed to obtain a tire tread, an undertread, a carcass, a side. It can be used not only for tires such as walls and beads, but also for anti-vibration rubber, belts, hoses and other industrial products.
Particularly, it is preferably used as rubber for tire tread.

[0041]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

In the examples, parts and% mean parts by weight and% by weight, unless otherwise specified.

Various measurements were made by the following methods.

The number average molecular weight of the polymer was measured by gel permeation chromatography and the differential refractive index.

The microstructure of the butadiene portion of the styrene-butadiene copolymer was determined by the infrared method (Morero method). The bound styrene content was determined from the calibration curve by infrared method based on the absorption of the phenyl group at 699 cm -1.

In polymerization using an organolithium initiator, even if a solvent sufficiently purified in advance is used, a part of the initiator is deactivated by impurities such as water and carbon dioxide in the polymerization system. It has been known. Therefore, in order to detoxify the impurities acting on the deactivation of the initiator in advance, it is generally added in an amount that does not participate in the polymerization as a scavenger, and is added in an amount necessary to detoxify the impurities. Has been done. In this example, a small amount of sec-butyllithium was added as a scavenger in advance during the polymerization reaction, and then a predetermined amount of the organolithium compound was added to carry out the polymerization. In this case, the organolithium compound added later was used as the amount of lithium at the end of the polymerization chain. Se to be added as a scavenger
The amount of c-butyllithium was slowly added little by little to the polymerization system containing the polymerization monomer and the solvent, and the amount was determined until the temperature rise of the polymerization system was observed. In this example, the same reactor was used, the same lot and the same amount of solvent, and the same lot and almost the same amount of monomers were used, so that the polymerization conditions were common in all the examples and comparative examples. Conceivable. As a result of the preliminary experiment, the amount of sec-butyllithium used as a scavenger was 0.33 mmol based on 1 kg of the polymerized monomer and the solvent, and in this example, this was added in this ratio before the polymerization in any case.

Tan δ was used as an index of hysteresis loss (rolling resistance) in the vulcanized product of the rubber composition.
It is evaluated that the smaller tan δ is, the lower hysteresis loss and the lower rolling resistance are. For the measurement of tan δ, a viscoelasticity measuring device (manufactured by Rheometrics) is used and the temperature is 50 ° C.
The strain was 1% and the frequency was 15 Hz.

The tensile properties are as specified in JIS K6301.
Was measured according to.

Pico abrasion was used as an index of abrasion resistance.
Pico abrasion was measured at room temperature using a Goodrich pico abrasion tester according to ASTM-D-2228.

The wet skid resistance value was measured at 25 ° C. by using a wet skid tester (manufactured by Stanley, England).
Measured on a wet asphalt surface.

Example 1 In a reactor equipped with a stirrer of 5 liters, 1500 g of cyclohexane, 200 g of 1,3 butadiene, 50 g of styrene and 1.3 g of tetrahydrofuran.
After charging 5 g and adjusting the temperature of the reaction vessel to 50 ° C, 0.08 g of n-butyllithium was added to initiate polymerization. Then, the polymerization was carried out at 50 ° C. for 90 minutes, 0.71 g of vinylbenzyldiethylamine was added, the mixture was stirred for 5 minutes, and then the polymerization was stopped with isopropyl alcohol.

Next, 2.5 g of 2,6-di-tert-butyl-p-cresol was added to the polymer-containing liquid and the solvent was removed by steam stripping to obtain a solid product at 100 ° C. It was dried with a hot roll to obtain a rubbery polymer polymer A. The properties of polymer A are shown in Table 1.

The polymer A was prepared according to the formulation shown in Table 2 by adding 2
Kneading and blending was performed with a 50 ml Labo Plastomill and a 3 inch roll. In the compounding, the natural rubber and the compound-monomer-added polymer were blended in the predetermined blending amounts shown in Table 3.

The compounded rubber was vulcanized at 145 ° C. for 30 minutes and then evaluated for its physical properties. The results are shown in Table 3.

Example 2 A polymer B was obtained in the same manner as in Example 1 except that 0.70 g of vinylbenzylpyrrolidine was added instead of vinylbenzyldiethylamine in Example 1 to carry out polymerization.

Example 3 A polymer C was obtained in the same manner as in Example 1 except that 0.75 g of vinylbenzylpiperidine was added instead of vinylbenzyldiethylamine in Example 1 to carry out polymerization.

Example 4 Polymer D was prepared in the same manner as in Example 1 except that 0.80 g of N-vinylbenzylazacycloheptane was added in place of vinylbenzyldiethylamine in Example 1 for polymerization. Got

Example 5 A reactor equipped with a stirrer of 5 liters was charged with 1500 g of cyclohexane, 200 g of 1,3-butadiene, 50 g of styrene, 0.56 g of vinylbenzylpyrrolidine and 1.08 g of tetrahydrofuran, and the reaction vessel temperature was 50. After adjusting to ° C, 0.064 g of n-butyllithium was added to initiate polymerization.
Then, the polymerization was carried out at 50 ° C. for 90 minutes, and then the polymerization was stopped with isopropyl alcohol. Next, 2.5 g of 2,6-di-tert-butyl-p-cresol was added to the polymer, the solvent was removed by steam stripping, and the obtained solid was dried with a hot roll to give a rubber-like polymer. Got Coalescence E. Polymer E was kneaded and blended with 250 ml of Labo Plastomill and a 3-inch roll according to the formulation shown in Table 2. Table 3 shows the physical properties of vulcanized rubber.
It was shown to.

Example 6 The amounts of vinylbenzylpyrrolidine, tetrahydrofuran and n-butyllithium in Example 5 were 0.7 g, 1.35 g and 0.
A polymer F was obtained in the same manner as in Example 5 except that the amount was 08 g.

Example 7 Polymer G was obtained in the same manner as in Example 5, except that 1.12 g was added instead of 0.56 g of vinylbenzylpyrrolidine in Example 5. Obtained.

Example 8 A reaction vessel equipped with a stirrer of 5 liters was charged with 1500 g of cyclohexane, 162.5 g of 1,3 butadiene, 87.5 g of styrene, 0.56 g of vinylbenzylpyrrolidine and 0.50 g of tetrahydrofuran, and a reaction vessel. After adjusting the temperature to 50 ° C, n-
Butyl lithium (0.064 g) was added to initiate polymerization. A polymer H was obtained in the same manner as in Example 5 except for the above.

Example 9 Instead of adding 1.08 g of tetrahydrofuran in Example 5, 1.
Polymer I was obtained in the same manner as in Example 5 except that 80 g was added.

Example 10 A reactor equipped with a stirrer of 5 liters was charged with 1500 g of cyclohexane, 200 g of 1,3-butadiene, 50 g of styrene, 0.70 g of vinylbenzylpyrrolidine and 1.35 g of tetrahydrofuran, and the reaction vessel temperature was 50 °. After adjusting to C, 0.08 g of n-butyllithium was added to initiate polymerization. After the polymerization was carried out at 50 ° C for 90 minutes, tin tetrachloride 0.0
The polymerization was stopped by adding 8 g. Next, 2.5 g of 2,6-di-tert-butyl-p-cresol was added to this polymer, the solvent was removed by steam stripping, and the obtained solid was dried on a hot roll at 100 ° C. Thus, a rubber-like polymer polymer J was obtained.

Example 11 The amounts of vinylbenzylpyrrolidine, tetrahydrofuran and n-butyllithium in Example 5 were 0.57 g, 0.675 g,
A polymer K was obtained in the same manner as in Example 5 except that the polymerization was carried out at 0.04 g.

[Example 12] The amounts of vinylbenzylpyrrolidine, tetrahydrofuran, and n-butyllithium in Example 5 were 0.33 g, 0.39 g, and
A polymer L was obtained in the same manner as in Example 5 except that the polymerization was carried out at 0.024 g.

[Example 13] A vulcanized product was obtained in the same manner as in Example 2 except that the polymer B and the natural rubber were blended in an amount of 40 parts by weight and 60 parts by weight, respectively. The results of evaluation of physical properties of vulcanized products are shown in Table 3.

Comparative Example 1 Polymer M was obtained in the same manner as in Example 1 except that vinylbenzyldiethylamine was not added.

Comparative Example 2 The amounts of vinylbenzylpyrrolidine, tetrahydrofuran and n-butyllithium in Example 5 were 1.50 g, 3.85 g and 0.2, respectively.
A polymer N was obtained in the same manner as in Example 5 except that the polymerization was performed at 3 g.

[Comparative Example 3] A vulcanized product was obtained in the same manner as in Example 2 except that the polymer B and the natural rubber were blended in an amount of 20 parts by weight and 80 parts by weight, respectively. The results of evaluation of physical properties of vulcanized products are shown in Table 3.

[0070]

[Table 1]

[0071]

[Table 2]

[0072]

[Table 3]

As shown in Table 3, the rubber compositions of Examples 1 to 13 are different in compound physical properties from those of the copolymer containing no compound monomer (Comparative Example 1) in physical properties of vulcanization. By the effect of the copolymer containing as a monomer unit, low hysteresis loss property is significantly improved, and, without impairing the fracture characteristics, wear resistance, a rubber composition excellent in balance with wet skid property It was revealed to be provided.

By using a copolymer containing an organic nitrogen compound such as vinylbenzyldiethylamine, vinylbenzylpyrrolidine, vinylbenzylpiperidine and N-vinylbenzylazacycloheptane as a compound monomer, the rubber composition has a low hysteresis. Excellent in
Moreover, it has been clarified that an excellent rubber composition having a well-balanced wear resistance and wet skid property can be obtained without impairing the fracture characteristics. (Examples 1 to 4)
Considering mainly the low hysteresis loss effect, the molecular weight of the copolymer containing the compound monomer is 9 × 10 ⁴ to 8
It was also found that 0 × 10 ⁴ was preferable, and no effect was observed below that (Comparative Example 2).

Further, in the most general blending system in which natural rubber and a polymer containing a compound monomer are blended, 30 parts by weight or more of the polymer of the present invention may be blended in 100 parts by weight of a rubber raw material. It was also found that this effect was not observed (Comparative Example 3) with the preferable amount (Examples 1 to 13) and the blending amount less than this amount.

Such a good effect of improving the physical properties is that the block copolymers obtained from the block copolymers (Examples 1 to 4 and 13) can be used as random copolymerization (Examples). 5 to 12), the same results were observed in the random copolymers, which were not restricted by the influence of the composition distribution of the compound monomer units, and further, a relatively high styrene content (Example 8) or a relatively high vinyl content was obtained. These effects are observed even with the copolymer having a bond content (Example 9).

It was also shown that it is possible to react a modifying agent such as tin tetrachloride at the polymerization chain end of the compound monomer-containing copolymer, whereby the low hysteresis effect is further improved (Examples). 6, 10)

[0078]

The present invention has the above-mentioned structure,
It is possible to provide a rubber composition that has a significantly low rolling resistance (hysteresis loss property) without impairing the fracture properties and is excellent in the balance between abrasion resistance and wet skid property. provide.

Continuation of the front page (56) Reference JP 58-154742 (JP, A) JP 64-70541 (JP, A) JP 62-119257 (JP, A) JP 64-22940 (JP , A) JP 62-265305 (JP, A) JP 57-34106 (JP, A) JP 4-252242 (JP, A) JP 50-29669 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 9/00 C08F 236/04 C08K 3/04 C08K 3/06

Claims (3)

(57) [Claims] 1. A conjugated diene or a conjugated diene and a vinyl aromatic hydrocarbon and an organic nitrogen compound represented by the following general formula A or general formula B are copolymerized in a hydrocarbon solvent using an organolithium compound as an initiator. was collected using a number average molecular weight Mn of 9 × 10 ⁴ ~80 × 10 ⁴ of the polymer rubber material 100 parts by weight containing 30 parts by weight or more, only the carbon black from 20 to 100 parts by weight relative to the rubber material Empty
And a vulcanizing agent in an amount of 0.1 to 5 parts by weight based on the rubber raw material. [Chemical 1] Is a group bonded to the benzene ring, and X is ( CR ₆ R ₇ ) n
Or a saturated ring-forming part consisting of ( CR ₈ R ₉ ) m and NR ₁₀ or O, or a carbon-carbon single bond in the saturated ring-forming part. It represents an unsaturated ring forming part having at least a part of carbon-carbon double bond. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ ,
R ₁₀ is hydrogen or an aliphatic group having 1 to 30 carbon atoms, an alicyclic group,
It represents a group selected from each aromatic hydrocarbon group and may be the same or different. However, R ₄ , R ₅ and
R ₁₀ does not contain a hydrogen atom. Further, n represents an integer of 3 to 10 and m represents an integer of 2 to 9. ) 2. Opening an organolithium compound in a hydrocarbon solvent.
Conjugated diene or conjugated diene and vinyl aromatic as initiator
Hydrocarbons and organic nitrogen compounds represented by the following general formula B
And a number average molecular weight Mn of 9 × 1
Rubber raw material containing 30 parts by weight or more of 0 ⁴ to 80 × 10 ⁴ polymer
100 parts by weight and 20 to 100 parts by weight of the rubber raw material
0.1 part by weight of carbon black and the rubber raw material
To 5 parts by weight of a vulcanizing agent
object. [Chemical 2] Is a group bonded to the benzene ring, and X is (CR ₆ R ₇ ) n
A saturated ring-forming moiety consisting of or (CR ₈ R ₉ ) m and
And a saturated ring-forming moiety consisting of NR ₁₀ or O, or
At least the carbon-carbon single bond in the saturated ring forming part.
Represents an unsaturated ring forming part with a part of carbon-carbon double bond
You R ₁ , R ₂ , R ₃ , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are water.
Elementary or C1-C30 aliphatic, alicyclic, aromatic
Represents a group selected from hydrocarbon groups, even if the same
It may be different. However, R ₁₀ does not include a hydrogen atom.
Yes. In addition, n represents an integer of 3 to 10 and m represents an integer of 2 to 9.
Forget ) 3. The rubber raw material has a number average molecular weight of 9 × 10 ⁴ to 80 obtained after the polymerization reaction which is substantially completed.
× 10 ⁴ polymer, a silicon compound, a tin compound, an isocyanate group in the molecule or -CM-N <bond (M: S
Or O) according to claim at least one compound selected from the containing compound is a polymer obtained by adding a modifier
The rubber composition according to 1 or 2 .