JP2587275B2 - Rubber composition for tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rubber composition for tires having excellent fuel efficiency.

[Conventional technology]

In response to recent demands for low fuel consumption and driving safety of automobiles, rubber materials for treads of automobile tires
A rubber material having a small rolling resistance, that is, a small hysteresis loss, and a large wet skid resistance, that is, a rubber material having a small tan δ at a high temperature and a large tan δ at a low temperature is required, and as a rubber material for a carcass,
A rubber material having a low heat generation, that is, a small hysteresis loss is required.

However, since the rolling resistance and the wet skid property required for the rubber material for the tread have a trade-off relationship, various improvements have been proposed in view of the molecular design of the polymer.

For example, a styrene-butadiene copolymer having a styrene content and a 1,2-vinyl bond content in a specific ratio (Japanese Patent Application Laid-Open No. 54-62248) and a product having a specific styrene chain distribution (Japanese Patent Application Laid-Open No. -143209), those having a specific vinyl bond chain distribution (JP-A-56-149413), and those using a high vinylstyrene-butadiene copolymer having a tin-butadienyl bond (JP-A-57-149413). 87407 and JP
Nos. 58-162605, JP-A-63-6566 and JP-B-63-6567, in which not only the styrene content and the 1,2-vinyl bond content but also the cis and trans content are made specific ratios. ) Have been proposed, but none of them has a sufficient improvement effect, and a rubber composition for tires having a further improvement effect is desired.

Among these, many methods have been proposed for introducing various compounds into a diene polymer having an active alkali metal and / or alkaline earth metal terminal. For example, those having a benzophenone having an amino group and / or a substituted amino group introduced therein (JP-A-58-141706), (Wherein M represents an oxygen or sulfur atom) (Japanese Unexamined Patent Publication No. 60-137913), and those incorporating an isocyanate compound (Japanese Unexamined Patent Publication Nos. Sho 61-141741 and 61 -188202), those incorporating a carbodiimide compound (JP-A-62-161844), (Wherein, R ₁ is a C ₁ -C ₆ alkyl group, etc., Y is an oxygen or sulfur atom, and n is an integer of 3-4). -43402), but there are still many problems, such as those with insufficient improvement effect, poor storage stability, and marked coloring, and new compounds without these problems have been introduced. A rubber and a rubber composition using the rubber have been strongly desired.

[Problems to be solved by the invention]

An object of the present invention is to provide a rubber composition for a tire that satisfies both a low rolling resistance and a high wet skid resistance in a trade-off relationship as rubber properties of the rubber composition for a tire. An object of the present invention is to provide a rubber composition useful as a tread or carcass rubber material for tires or all season tires.

[Means for solving the problem]

The present invention relates to a diene polymer having an active terminal, which is obtained by a polymerization reaction using an alkali metal and / or alkaline earth metal catalyst as an initiator, that is, an alkali metal and / or
Or a polymer or copolymer obtained by reacting a diene polymer or a conjugated diene-aromatic vinyl copolymer having an alkaline earth metal terminal with an organic compound having a specific atomic group represented by the following formula A, A rubber composition for tires comprising at least 20 parts by weight of a diene polymer rubber (hereinafter, referred to as a modified diene polymer rubber) in all rubbers.

Formula A [In the above formula A, R ₁ represents a methyl group or an ethyl group or a nitro group optionally substituted with an amino group, a phenyl group optionally substituted with chlorine, and R ₂ represents an alkoxy group, an amino group, a nitro group. Group, an alkyl group having 1 to 18 carbon atoms which may be substituted by chlorine, an aralkyl group, an alkenyl group, an aryl group, and a trialkylstannyl group.

X represents a divalent carboxylic acid residue. Hereinafter, the present invention will be described in detail.

In the present invention, the diene polymer or the conjugated diene-aromatic vinyl copolymer having an alkali metal and / or alkaline earth metal terminal is polymerized using an alkali metal and / or alkaline earth metal base catalyst. It is a polymer.

Among such polymerization catalysts, examples of the alkali metal catalyst include organic lithium base catalysts such as ethyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, and phenyllithium. Examples of the metal-based catalyst include a barium (Ba) tertiary alkoxide / dibutyl Mg complex, and a composite catalyst composed of barium (Ba) alcoholate or phenolate / organic lithium compound or organomagnesium compound / organoaluminum compound. it can.

Examples of the conjugated diene monomer for obtaining a diene polymer include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene, and preferably 1,3-butadiene. It is. On the other hand, examples of aromatic vinyl monomers for obtaining a conjugated diene-aromatic vinyl copolymer include styrene, methylstyrene, and vinyl toluene, and styrene is preferred.

Examples of the compound represented by the formula A to be reacted with a diene polymer having an alkali metal and / or alkaline earth metal terminal include a pyridazone or phthalazone compound.

The pyridazone or phthalazone compound is represented by the following formula I
2-phenyl-6-benzyloxy-3-pyridazone represented by the following formula II, 2-phenyl-6-allyloxy-3-pyridazone represented by the following formula II, 2-phenyl-6- (tri-n -Butylstannyloxy) -3
-Pyridazone, 2-dimethylaminomethyl-6-allyloxy-3-pyridazone, 2-phenyl-4-benzyloxy-1-phthalazone, 2-morpholinomethyl-4-benzyloxy-1-phthalazone, 2- (p-dimethyl Aminophenyl) -4-allyloxy-1-phthalazone, 2
-Phenyl-4- (tri-n-butylstannyloxy) -1-phthalazone and the like.

The pyridazone or phthalazone compound may be reacted alone, or in the benzophenones and / or in the molecule. (Wherein M represents an oxygen or sulfur atom). The amount of the pyridazone or phthalazone compound used is 0.1 to 5.0 moles per mole of the active diene polymer, and when used in combination with other modifiers, the total amount is also 0.1 to 5.0 moles per mole of the active diene polymer. Is a mole. If less than 0.1 mol, there is no effect of improving the rebound resilience. On the other hand, if it exceeds 5 mol, the effect of improvement is saturated, and rather, thermal stability and heat aging resistance are unpreferably decreased.

The modified diene polymer rubber which is a reaction product of the pyridazone or phthalazone compound and the diene polymer,
It is necessary to mix at least 20 parts by weight in all rubber. If the amount of the modified diene-based polymer rubber is less than 20 parts by weight, the improvement in resilience of the resulting rubber composition is small, and no improvement in rolling resistance can be expected.

Examples of target rubbers to be blended with the modified diene polymer rubber include natural rubber, synthetic polyisoprene rubber, butadiene rubber, styrene-butadiene copolymer rubber, and ethylene-propylene copolymer rubber.

Carbon black blended in the rubber composition of the present invention also
Any of GPF, HAF, N339, ISAF, and SAF may be used, but it is preferable to use N339 grade carbon black having a wide aggregate distribution as a tread rubber composition for a fuel-efficient tire.
Further, the rubber composition of the present invention, as other rubber compounding agents, various known compounding agents, for example, fillers, anti-aging agents, softeners, vulcanizing agents, vulcanization aids, vulcanization accelerators Needless to say, such compounds are blended.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

Examples 1-4 A 2 l stainless steel polymerization reactor was washed and dried,
After replacing with dry nitrogen, 120 g of 1,3-butadiene as a monomer, 720 g of cyclohexane as a polymerization solvent, 0.15 g of N, N, N'N'-tetramethylethylenediamine as a vinylating agent, n-butyllithium (15% n- Hexane solution (0.9 mmol) was added, and polymerization was carried out at 50 ° C. for 2 hours while stirring the contents. After the completion of the polymerization reaction, a pyridazone or phthalazone compound shown in Table 2 was added by the weight shown in Table 2, and the mixture was stirred for 30 minutes to perform a denaturation reaction. After completion of the reaction, the resulting polymer solution was washed with 2,6-di-t-butyl-
The resulting modified diene polymer was taken out into methanol containing 1.5% by weight of p-cresol (BHT), coagulated, and dried at 60 ° C. for 24 hours under reduced pressure. Mooney viscosity and vinyl bond content of the modified diene polymer rubber obtained by drying were measured.

 Mooney viscosity was measured according to JIS K-6300.

The vinyl bond content was determined by the method of D. Morero et al. (Chem.e., Vo
l.41, p.758, 1957).

The resulting modified diene polymer rubber was compounded according to the compounding recipe shown in Table 1, mixed with an internal mixer and an open roll, and then press-vulcanized at 160 ° C. for 45 minutes to measure desired physical properties. .

Table 2 shows the characteristic values of the modified diene polymer rubber, and Table 3 shows the physical properties of the vulcanized rubber.

 In addition, the measuring method of each physical property value in a table | surface is as follows.

Tensile test: Measured according to JIS K 6301.

Rebound resilience: Measured in accordance with JIS K 6301.

Pico wear: Conforms to ASTM D-2228. Exponential display with VBR5 as 100.

Wet skid resistance: Measured with a British portable skid tester, use a safety walk (manufactured by 3M), wet the road with distilled water
Measured at a temperature of ° C. Exponential display with VBR5 as 100. Therefore, the larger the value, the better.

tan δ: Measured by using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under conditions of elongation and deformation at a strain rate of 10 ± 2% and a frequency of 20 Hz.

Comparative Example 1 In the above example, after completion of the polymerization reaction of 1,3-butadiene, a polymer solution produced without adding the pyridazone or phthalazone compound shown in Table 2 was replaced with 2,6-di-t-butyl- The procedure was performed in the same manner as in Example 1 except that p-cresol (BNT) was taken out in methanol containing 1.5% by weight. The results are shown in Tables 2 and 3.

Examples 5 and 6 5 kg of benzene in a 10-liter stainless steel reactor equipped with a stirrer
200 g of styrene, 800 g of butadiene and 1.2 g of N, N, N'N'-tetramethylethylenediamine were added and the reactor temperature was raised to 40.
After the temperature was raised to 7.0 ° C., 7.0 mmol of n-butyllithium (15% n-hexane solution) was added to initiate polymerization. After conducting a polymerization reaction at a reaction temperature of 40 ° C. for 120 minutes, a pyridazone or phthalazone compound shown in Table 2 was added by the weight shown in Table 2 and stirred for 30 minutes to perform a denaturation reaction. After the reaction, methanol was added as a terminator to the resulting polymer solution.
Add 5 ml, add 10 g of BHT, coagulate with steam, add 60 ml
Drying under reduced pressure at 24 ° C. for 24 hours gave a modified diene copolymer rubber. The Mooney viscosity, vinyl bond content and physical properties of the vulcanized rubber of the resulting modified diene copolymer rubber were determined in Example 1.
The measurement was carried out in the same manner as in Examples 4 to 4, and the results are shown in Tables 2 and 3.

Comparative Example 2 The procedure of Example 5 was repeated, except that, after the completion of the polymerization reaction, 5 ml of methanol was added as a terminator to the polymer solution produced without adding the pyridazone or phthalazone compound shown in Table 2. went. The results are shown in Tables 2 and 3.

Examples 7 and 8 A polymer reactor made of sterence having an internal volume of 2 liters was washed, dried and replaced with dry nitrogen, and then 120 g of 1,3-butadiene as a monomer and 720 g of cyclohexane as a polymerization solvent were charged. After adding 2.2 mmol (based on magnesium) of dibutylmagnesium / triethylaluminum complex (molar ratio Mg / Al = 5.0) and 0.44 mmol of t-butoxybarium, a polymerization reaction was carried out at 60 ° C. for 5 hours while stirring the contents. . After the completion of the polymerization reaction, a pyridazone or phthalazone compound shown in Table 2 was added only for the polymerization shown in Table 2, and the mixture was stirred for 30 minutes to perform a modification reaction.

After completion of the reaction, the resulting polymer solution was washed with 2,6-di-t-
The resulting modified diene polymer was taken out in methanol containing 1.5% by weight of butyl-p-cresol (BHT), solidified, and dried under reduced pressure at 60 ° C. for 24 hours. Mooney viscosity and vinyl bond content of the modified diene polymer rubber obtained by drying were measured.

The modified diene polymer rubber of the above reaction product was prepared in Example 1.
And vulcanized to obtain a vulcanized product. The measurement results of physical properties of the vulcanized rubber are shown in Tables 2 and 3.

Comparative Example 3 In the same manner as in Example 7, except that 5 ml of methanol was added as a terminator to the polymer solution produced without adding the pyridazone or phthalazone compound shown in Table 2 after the polymerization reaction was completed. went. The results are shown in Tables 2 and 3.

As is clear from the examples of Table 3, the modified diene-based polymer rubber obtained by reacting the compound of the formula A with the same microstructure as that of Comparative Example 1 as compared with the polybutadiene rubber of Comparative Example 1 (Experiment No. 5) The rubber compositions of Examples 1 to 4 containing
The tan δ at 60 ° C. is greatly reduced without lowering the tan δ at ° C., and the abrasion resistance of the rubber compositions of Examples 1 to 4 are clearly better than those of the comparative examples. Also, in the case of a styrene-butadiene copolymer rubber, the rubber compositions of Examples 5 and 6 containing the modified diene-based polymer obtained by reacting the compound of the formula A had a polybutadiene rubber having a higher molecular weight than that of Comparative Example 2. As in the case, the tan δ at 60 ° C is greatly reduced, and the breaking strength is also good. Furthermore, in the case of high trans polybutadiene rubber, the rubber compositions of the present invention of Examples 7 and 8 have the same tan δ at 0 ° C., wet skid resistance, etc., and a large decrease in tan δ at 60 ° C., as compared with Comparative Example 3. doing. Example 9
The rubber compositions of Nos. 13 to 13 are blends with other diene rubbers, all of which exhibit the above-mentioned excellent properties. In particular, Examples 9 to 12 in which the rubber compositions are blended with natural rubber have a remarkable tendency.

〔The invention's effect〕

As described above, the rubber composition containing the modified diene-based polymer rubber of the present invention has a large tan δ at 0 ° C., that is, a good skid resistance and a very small tan δ at 60 ° C.
That is, it is a rubber composition having extremely low rolling resistance, and is not only extremely excellent as a rubber material for treads of fuel-efficient tires and all-season tires, but also has low heat generation due to low heat generation (high rebound resilience). It is also very suitable for the required tire members, for example, carcass coat rubber, base tread rubber, sidewall rubber and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenichi Narusou 2-15-33 Isogo Isogo-ku, Yokohama-shi, Kanagawa Japan Zeon Isogo Dormitory

Claims (1)

(57) [Claims] 1. A diene polymer rubber which is a reaction product of a diene polymer or a conjugated diene-aromatic vinyl copolymer having an alkali metal and / or alkaline earth metal terminal with a compound represented by the following formula A: The whole rubber in at least 20
A rubber composition for tires, which is compounded by weight. Formula A [In the above formula A, R ₁ is a methyl group or an ethyl group or a nitro group which may be substituted with an amino group, a phenyl group which may be substituted with chlorine, and R ₂ is an alkoxy group, an amino group, a nitro group. X represents an alkyl group having 1 to 18 carbon atoms which may be substituted by chlorine, an aralkyl group, an alkenyl group, an aryl group or a trialkylstannyl group, and X represents a residue of a divalent carboxylic acid. ]