JPS61103902A - Production of diene copolymer rubber - Google Patents

Abstract

PURPOSE:To obtain a rubber useful for tire tread use with resilience and wet- skid resistance in good balance, by the reaction between a diene copolymer rubber having active dienyl-alkali metal bond terminal and a specific compound. CONSTITUTION:(A) A conjugated diene monomer (e.g., 1,3-butadiene, vinyltoluene) and (B) an aromatic vinyl monomer (e.g., styrene, vinyltoluene) are polymerized in a hydrocarbon solvent (e.g., propane, benzene) using an organic alkali metal initiator (e.g., methyllithium) normally in such a weight ratio (A)/(B) as to be 95-65/5-35 to form a conjugated diene-aromatic vinyl copolymer rubber with the molecular chain end being dienyl-alkali metal. The resultant rubber and a compound having in the molecule a bond of formula (M is O or S) (e.g., acetamide, epsilon-caprolactam) are made to react, thus obtaining the objective rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a diene copolymer rubber having improved anti-shock elasticity.
The present invention relates to a method for producing a diene copolymer rubber, which comprises reacting a diene copolymer rubber having an active dienyl-alkali metal bond terminal with a specific compound.

[Prior art]

In recent years, due to demands for lower fuel consumption and driving safety for automobile tires, rubber materials with low rolling friction resistance and high wet skid resistance have been strongly desired as rubber for automobile tire treads. K, which reduces rolling friction resistance, requires higher recoil elasticity of the rubber material. However, these two properties are contradictory, and various methods for improving polymers have been proposed in order to harmonize these two properties. For example, a method (4!-
1982-62248), a method for obtaining a specific styrene chain distribution (JP-A-56-143209), a method for obtaining a specific vinyl bond chain distribution (JP-A-56-149413)
, a method of introducing a soenyl-tin bond into a molecular chain (Japanese Unexamined Patent Publication No. 57-87407), etc. have been proposed.

[Problems to be solved by the invention and means of solving them]

The present inventors first reacted an alkali metal addition diene polymer with a compound having a -C-N< bond (in the formula, M is 0 or S) in the molecule to form a specific atomic group into a polymer chain. It has been found that the above-mentioned properties can be improved by introducing a 9jinine-based polymer into the polymer (Japanese Patent Application No. 58-249100).

The present inventors further developed a conjugated diene monomer and an aromatic compound with improved high anti-reflection properties. In order to develop a copolymer with Nyl monomer, various improvements to the above-mentioned method of introducing a specific atomic group have been investigated.

As a result, by reacting the copolymer having a dienyl-alkali metal bond terminal with a specific compound,
It has been discovered that a diene copolymer rubber with a better balance between rolling resistance (resilience) and wet skid resistance can be obtained, and the present invention has been achieved.

The purpose of the present invention is to provide a method for producing a diene copolymer having an excellent balance between rolling resistance (rebound elasticity) and wet skid resistance. A monomer and an aromatic vinyl monomer are polymerized using an organic alkali metal initiator to form a conjugated diene-aromatic vinyl copolymer rubber which is a uni-alkali metal at the end of the molecular chain, and then the copolymer is Rubber and 10-N bonds in the molecule (where M is 0 atom or S
This is particularly achieved by reacting a compound having an atom (representing an atom).

The feature of the present invention is to react a conjugated diene-aromatic vinyl copolymer rubber whose polymer chain ends are dienyl-alkali metal with the above-mentioned compound. Resilience is significantly improved compared to when using copolymer rubber.
.

Generally, when a conjugated diene monomer and an aromatic vinyl monomer are copolymerized in a hydrocarbon solvent using an organic alkali metal initiator, the copolymerization reactivity of the former is overwhelmingly greater than that of the latter. For example, M.

According to Morton, in benzene solvent r, (butadiene) = 4.5, r2 (styrene) = 0.08 ~
o, 41 Journal of Polymer Science (J, Polymar, Sci, ) #
61, p. 25 (1962).

This large difference in copolymerization reactivity is due to the fact that the conjugated diene monomer is consumed in the first half of the polymerization, so that a large amount of aromatic vinyl monomer remains in the polymerization system at the end of the polymerization.
This means that the number of active ends with alkali metal bonds increases. For example, when butadiene and styrene are polymerized in a hydrocarbon solvent using n-butyllithium as a catalyst, at low polymerization rates, the color of the polymerized system is light yellow, which is characteristic of the butadiunyl anion. It is clear from the observation that when the polymerization rate increases, Haboputage/ is consumed, and a large amount of styrene remains, the color of the system changes to the reddish-orange color characteristic of steryl anions, and the polymerization rate also increases.

The present invention is characterized in that a conjugated diene-aromatic vinyl copolymer copolymer having a noenyl-alkali metal bond terminal is reacted with a specific compound, and the monomer unit immediately before the dienyl-alkali metal bond terminal is conjugated. It may be a diene or an aromatic vinyl.

In addition, the method of making the end of the copolymerized pum with a genyl alkali metal is, for example, the method of adding a conjugated diene monomer after the copolymerization is completed (usually, the amount of the monomer added is equal to or more than the amount of the active alkali metal end). It would be nice if there was, but 10~
About 100 times the molar amount is preferable. ), copolymerization in a polymerization vessel equipped with a reflux condenser, or any other method in which the end of the polymer chain becomes a diene, and is not particularly limited.

fly as a conjugated diene monomer used in the present invention. 3
-butadiene, isoprene, 1,3-pentadiene, 2
,3-dimethyl-1,3-butadiene,1,3-hext
Examples include diene. Examples of aromatic vinyl %/mer include ld styrene, α-methylstyrene p-methylstyrene, vinyltoluene, vinylnaphthalene, and the like. The ratio of the conjugated diene monomer to the aromatic vinyl monomer is 95-50:5-50, preferably 95-65:5-350.

The organic alkali metal initiators used in the present invention may be those used in ordinary solution polymerization, and organic lithium initiators are particularly preferred. For example, methyllithium, ethyllithium 1 n-propyllithium, i-propyllithium, n-butyllithium, 5ee-butyllithium, t-butyllithium, octyllithium, n-decyllithium, phenyllithium, 2-naphthyllithium,
Examples thereof include 2-f-thyl-phenyllithium, 4-phenyluttyllithium, cyclohexyllithium, 4-cyclopentyllithium, and 1,4-dilithio-butene-2. The amount of organic alkali metal initiator used is usually in the range of 0.2 to 20 mmol per 100 grams of edible food.

Copolymer run/llJ with organic alkali metal initiator
Polar compounds such as ether compounds, amine compounds, and phosphine compounds can be used for the purpose of controlling the proportion of vinyl bonds in the conjugated monomer.

The hydrocarbon solvent used in the present invention is selected from aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons, such as propane, n-butane, l-butane, n-pentane,
1-pentane, n-hexane, cyclohexane, propane, 1-butene, l-butene, 2-butene,
Cis-2-butene, 1-pentene, 2-pentene, 1-
Preferred solvents include hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. Furthermore, two or more of these solvents may be used in combination. The ratio of the solvent to the solvent is determined by the viscosity of the polymerization solution, the stirring power and heat removal capacity of the polymerization vessel, and is generally used at a weight ratio of 1:10 to 1:1.

The polymerization temperature was carried out in the temperature range of -20°C to 150°C.

However, a temperature range of 40 to 120°C is preferred.

Polymerization can be carried out either at elevated or constant temperature.

(M in the formula represents an O atom or an S atom) such as formamide, N,N-dimethylformamide, acetamide, N,N-diethylacetamide, aminoacetamide, N,N-dimethyl-N,N' -tumethylaminoacetamide, N,N-tumethylaminoacetamide, N,N'-ethylaminoacetamide, N,
N-dimethyl-W-ethylaminoacetamide, acrylamide, N,N-dimethylacrylamide, N,N-
Dimethylmethacrylamide, nicotinamide, isonicotinamide, picolinic acid amide, N,N-dimethylisonicotinamide, succinic acid amide, heptalic acid amide, N
, N , N', N'-nato-2-methylphthalic acid amide,
Oxamide, N,N,N',N'-tetramethyloxamide, 2-furancarboxylic amide, N,N-dimethyl-2-furancarboxylic amide, quinoli/-2-carboxylic acid amide, N-ethyl- Amide compounds such as N-methyl-quinolinecarboxylic acid amide, imide compounds such as succinimide, N-methylsuccimide, maleimide, N-methylmaleimide, 7thalimide, N-methylphthalimide, 8-casololactam, N-methyl-ε- 2 such as cagzoloctam, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2-piperidone, N-methyl+2+piperidone, 2-quinolone, N-methyl-2-quinolone, etc.
lactam compound, urea, N,N'-dimethylurea, N,N
-diethylurea, N,N,N',N'-tetramethylurea, N,N-trimethyl-N',N'-diphenylurea,
Urea compounds such as N,N'-dimethylethylene urea, carbamate derivatives such as methyl carbamate, methyl N,N-diethylcarnomate, incyanuric acid, N-
rtr-) incyanuric acid derivatives such as dimethylisocyanuric acid, and their corresponding thiocal? Examples thereof include nil-containing compounds, but the compound is not particularly limited as long as it is a compound having the bond that reacts with the alkali metal at the end of the polymer chain.

The amount of these compounds used is per mole of diene copolymer rubber having active dienyl-alkali metal bond terminals,
Preferably it is 0.5 mol or more.

If the amount is less than 0.5 mole, the improvement in anti-shock elasticity is insufficient.
．． 6, i, o mole) does not participate in the reaction even if used in large quantities,
There is no further improvement in rebound resilience. The temperature and reaction time of the reaction with the diene copolymer rubber having a dienyl-alkali metal bond can be selected within a wide range, but are generally from room temperature to 100°C and for several seconds to several hours.

After the reaction, the modified diene polymer rubber is used in the production of rubber by adding a coagulant such as alcohol such as methanol or ethanol to the reaction solution, or by normal solution polymerization such as steam coagulation. The coagulation method is used as is, and the coagulation temperature is not particularly limited. 5 For drying the crumb separated from the reaction system, band dryers, extrusion type dryers, etc. used in the production of ordinary synthetic crumbs can be used, and the drying temperature is not limited. is not particularly limited.

The diene copolymer rubber thus obtained has an excellent balance between rebound resilience and wet skid resistance, and is useful as a tire tread material.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 (1) A stainless steel polymerization reactor with an internal volume of 21 cm was washed, dried, and replaced with dry nitrogen, and then 1,3-butadiene 1
20g, Styrene Y409, Cyclohexane 840, l
i', 0.4 mmol of tetramethylethylenediamine,
1.0 mmol of n-butyllithium (n-hexane solution) was added, and polymerization was carried out at 45° C. for 5 hours while stirring the contents. Then, add 50g of a mixture of butadiene and cyclohexane with a butadiene concentration of 1% by weight.
After reacting at 5° C. for 15 minutes, 1 mmol of the compound shown in Table 1 was further added, and the addition reaction was carried out for 30 minutes. Thereafter, 511 Lt of methanol was added to stop the reaction, and the polymer solution was taken out into a methanol solution containing 1.5 wt. After solidifying the rubber, 6
Dry under reduced pressure at 0°C for 24 hours (Column & AXB,
C, D, E, F).

(2) A copolymer rubber was obtained under the same conditions as in (1) except that the compounds shown in Table 2 were added immediately after the copolymerization reaction of butadiene and styrene was completed without adding butadiene (Rubber AGXH) .

The vinyl bond content and styrene content of the polymer thus obtained were determined by infrared spectroscopy (Hampton,
Anal, Chsmp 21 + 923 (19
49)]. The results are shown in Table 1 along with the Mooney viscosity of the polymer.

These copolymer rubbers were cross-mixed with each compounding agent in a Terrapenda type mixer with a capacity of 250 WLt according to the compounding recipe shown in Table 2 to obtain a rubber compounded composition. This product was press-vulcanized at 160° C. for 25 minutes to prepare a test piece. The impact resilience of the vulcanized rubber was measured at 50° C. using a Danguchi buttripmeter.

Wet skid resistance was measured on a 23℃ road surface (ASTME-303) using a portable skid tester manufactured by Stanley.
-74, 3M Outdoor Type B1 Black, Safety Walk).

The results are shown in Table 3.

Table 2 Compounding recipe Copolymer rubber 100 parts by weight Zinc white & 3
3 Stearic acid 2 Sulfur 1.751 N-cyclohexyl-2-benzo 1.11 Thiazolesulfenamide HAF kaden black 50 1 Aromatic process oil 5 Table 3 From the results shown in Table 3, butadiene obtained by the method of the present invention −
Styrene copolymer rubber has extremely high rebound resilience, and tires using this rubber in their tire treads are thought to have a good balance of rolling resistance, wet skid, and slip resistance.

Example 2 (1) After copolymerization and polymerization of post-added butadiene under the same conditions as in Example 1 (1) except that the amounts of butadiene and styrene charged were changed to the amounts shown in Table 4,
1.0 mmol of N,N,N',N'-tetramethylurea was added and reacted to obtain a copolymer rubber (co9m AJ,
K).

(2) Copolymerization was carried out under the same conditions as in Example 1 (1) except that the amount of tetramethylethylenediamine added was changed to the amount shown in Table 4, the polymerization of post-added butadiene, and N, N,
A reaction with 1.0 mmol of N',N'-nato-2-methylurea was carried out to obtain a copolymer rubber (rubbers AL, M).

Blends of these copolymers were prepared using the same formulation as in Example 1, and the rebound elasticity, cross-resistance, and toss skid resistance of each vulcanizate were measured. The results are shown in Table 5.

Table 5

Claims (1)

[Claims] Polymerize a conjugated diene monomer and an aromatic vinyl monomer in a hydrocarbon solvent using an organic alkali metal initiator to produce a conjugated diene-aromatic vinyl copolymer rubber in which the end of the molecular chain is a dienyl-alkali metal. After that, the copolymer rubber is reacted with a compound having a ▲numerical formula, chemical formula, table, etc. ▼bond (in the formula, M represents an O atom or an S atom) in the molecule. Method for producing diene copolymer rubber.