JPH0617425B2 - Method for producing conjugated diene-based copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. TECHNICAL FIELD The present invention relates to a method for producing a copolymer having a distribution of vinyl aromatic compound and vinyl bond content in a polymer chain.

b. 2. Description of the Related Art Recently, with respect to rubber materials for automobile tires, rolling friction resistance is low to reduce fuel consumption, wet skid resistance is high to improve braking characteristics on a wet road surface, and snow road resistance is high. It is required that the ice skid resistance be large in order to improve the braking characteristics, and that the breaking strength be large in order to improve the durability. As a rubber material satisfying these characteristic values, a polymer containing polymer segments having different glass transition temperatures over a wide range is required. Such a polymer is a scanning calorimeter (DS
It exhibits characteristics such as broadening the width of the endothermic transition region of the glass transition temperature (Tg) by C) and widening the temperature dispersion width of the extinction of dynamic viscoelasticity (tan δ) of the vulcanizate. Conventionally, as a method of obtaining a polymer containing segments having different glass transition temperatures, a method of binding two random styrene-butadiene copolymers having different bound styrene contents in a block shape using an organolithium compound as an initiator, and further a block shape A method is known in which, after being bound to, the compound is bound radially with a polyfunctional coupling agent. Further, JP-A-56-143209 discloses that a styrene-butadiene copolymer having a specific molecular terminal structure is excellent in rolling resistance characteristics and wet grip, but in this case, in terms of rolling friction resistance. ,
Is insufficient. Further, JP-A-59-142214 discloses a method for producing a styrene-butadiene copolymer in which a method for additionally adding a monomer is specified. In this case, in terms of the balance between wet kid resistance and ice skid resistance characteristics. Is insufficient. Similarly, using an organolithium compound as an initiator, the amount of ether added is varied during the polymerization to obtain two polymers (polybutadiene-polybutadiene, polybutadiene-styrene butadiene copolymer, styrene) having different 1,2 bond contents in the polybutadiene portion. It is known that a butadiene copolymer-styrene-butadiene copolymer or the like) is bonded in a block form, and then a block-shaped bond is formed and then a polyfunctional coupling agent is used to form a radial bond.

c. Problems to be Solved by the Invention However, since the polymers obtained by these methods have two segments having different glass transition temperatures, tan δ
The broadening of the temperature dispersion width is limited, and there is a problem that the wet skid resistance and the ice skid resistance are in a trade-off relationship and the fracture strength is poor. Further, a method of polymerizing 1,3-butadiene in the presence of an ether compound at an elevated temperature or a method of copolymerizing 1,3-butadiene and styrene using an organic lithium initiator is known. The polymer obtained by the former method contains segments having different 1,2 bond contents in the polybutadiene molecular chain, but the broadening of the temperature dispersion width of tan δ of the vulcanized product is limited, and the fracture strength is also poor. . The polymer by the latter method, the temperature dispersion width of tan δ of the vulcanized product becomes wide, but since the polystyrene block is formed below the polymer, the value of tan δ at 50 to 80 ° C. of the vulcanized product becomes large, It is not preferable in terms of rolling friction resistance.

The present inventors have found that the vulcanized product has a wide temperature dispersion range of tan δ, and
The present invention has been achieved as a result of intensive studies on a method for easily obtaining a conjugated diene-based copolymer having a small tan δ at 0 to 80 ° C.

d. Means for Solving the Problems In order to solve the above problems, the present invention is directed to solving the above problems by using an organic lithium compound as an initiator in a hydrocarbon solvent in an amount of 5 to 35 parts by weight of a vinyl aromatic compound and a conjugated diene compound 95 to 65
The presence of a polyether or a tertiary polyamine in producing a conjugated diene-based copolymer containing 20 to 70% of 1,2 bonds and / or 3,4 bonds by polymerizing a monomer mixture consisting of Under the following conditions, the polymerization initiation temperature is -10 to 50 ° C, the highest polymerization temperature is 50 to 120 ° C, and the polymerization conversion temperature is 50 ° C to 120 ° C. When 90% to 99% is reached, 1 to 5 parts by weight of the conjugated diene compound is continuously or intermittently added, and further polymerization is carried out, and the polymerization is terminated by the polyfunctional coupling agent. The present invention provides a method for producing a characteristic conjugated diene-based copolymer.

Examples of the conjugated diene compound used in the present invention include 1,3-butadiene, isoprene, 1,3-pentadiene and 2,3-dimethylbutadiene, and preferably 1,3-butadiene and isoprene.

Examples of the vinyl aromatic compound include styrene, P-methylstyrene, O-methylstyrene, P-butylstyrene, vinylnaphthalene and the like, with styrene being preferred.

As the hydrocarbon solvent, one or more selected from butane, pentane, 2-methylbutene, 1-methylbutene, hexane, heptane, cyclohexane, methylcyclopentane, octane, benzene and the like can be used. The amount of the hydrocarbon solvent is 2 to 10 parts by weight based on 1 part by weight of the monomer mixture.

N-butyllithium as the organolithium compound, sec
-Butyl lithium, tert-butyl lithium, n-hexyl lithium, 1,4-dilithiobutane, a reaction product of butyl lithium and divinylbenzene, etc. are used.

The amount of the organolithium compound is 0.0 with respect to 100 parts by weight of the monomer.
Used in an amount of 1 to 0.2 parts by weight.

As the polyether and the tertiary polyamine, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether,
Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, 2-methoxymethyl tetrahydrofuran, 2,5-
Dimethoxymethyltetrahydrofuran, N, N, N, 'N' tetramethylethylenediamine, 1,2-dipiperidinoethane and the like can be mentioned.

Diethyl ether, tetrahydrofuran, dioxane,
Pyridine, ethers such as triethylamine and tertiary
When a secondary amine is used, the microstructure of the conjugated diene-based copolymer part is less dependent on the polymerization temperature.
Not preferable.

The amount of the polyether or tertiary polyamine used is in the range of 0.01 to 3 mol, preferably 0.05 to 1 mol, per 1 atomic equivalent of lithium of the organic lithium compound, and the average 1,2 bond of the conjugated diene copolymer is used. The total of 3,4 bond content is 20
Adjusted to be in the range of ~ 70%.

The polymerization reaction is carried out in a hydrocarbon solvent with a polyether or tertiary
Using an organolithium compound as an initiator in the presence of a primary polyamine, a monomer mixture of 5 to 35 parts by weight of a vinyl aromatic compound and 95 to 65 parts by weight of a conjugated diene compound is prepared at a polymerization initiation temperature of −.
Polymerization starts at 10 to 50 ° C and the maximum temperature reached is 60 to 120
It is carried out so that the temperature is within the range of ℃, and the temperature difference between the highest temperature reached and the temperature of initiation of polymerization is at least 40 ℃ or more. The difference between the maximum polymerization temperature and the polymerization initiation temperature is at least
At 40 ° C. and below 40 ° C., the peak width of tan δ temperature dispersion of the vulcanizate of the produced conjugated diene copolymer is narrow, and it is difficult to achieve both wet skid resistance and ice skid resistance.

The polymerization initiation temperature is −10 to 50 ° C., the polymerization initiation rate is slow at −10 or lower, and it is difficult to broaden the peak width of tan δ temperature dispersion of the vulcanizate at 50 ° C. or higher.

The maximum temperature reached for polymerization is 60 to 120 ° C. It is difficult to broaden the peak width of tan δ temperature dispersion of vulcanizates below 60 ° C, and copolymers of low molecular weight components are formed above 120 ° C. However, it is not preferable in terms of rolling friction resistance.

Following the polymerization reaction, a polyfunctional coupling agent is reacted. As a polyfunctional coupling agent, Japanese Examined Patent Publication Sho 49-36957
It is possible to use those described in the publication. This improves rolling friction resistance and fracture strength.

A preferred polyfunctional coupling agent added after the completion of polymerization is tin tetrachloride as a tin halide compound,
Examples thereof include dibutyldichlorotin and triphenyltin chloride, and examples of the organic carboxylic acid tin compound include dibutyldilauryltin, butyltristearyltin, and dimethyldistearyltin. Further, vinyltin compounds include monovinyltributyltin and divinyldibutyltin, and isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and crude diphenylmethane diisocyanate. Furthermore, the dialkylamino-substituted aromatic compound containing at least one of an epoxy group, a ketone group, an aldehyde group, an ester group, and a nitrile group is a compound represented by the following general formula.

When the polymerization conversion rate reaches the range of 90 to 99, preferably 95 to 99%, 1 to 5 parts by weight of the conjugated diene compound is continuously or intermittently added to the polymerization system to carry out further polymerization. Be done. Even if the conjugated diene compound was added at a stage where the polymerization conversion rate was less than 90% or more than 99%, the randomized polymerization of the conjugated diene compound and the vinyl aromatic compound was incomplete, and the polyvinyl aromatic compound was less than the polymer. And a vulcanized product is not preferable in terms of rolling friction resistance. A predetermined amount of the conjugated diene compound is added when the polymerization conversion reaches 90 to 99% to randomly polymerize the vinyl aromatic compound, and then the vinyl aromatic compound can be treated with a polyfunctional coupling agent.

When the conjugated diene to be added is less than 1 part by weight, the conjugated diene, the vinyl aromatic compound and the randomized polymerization are incomplete,
Rolling friction resistance increases. If it exceeds 5 parts by weight, the number of lithium active terminals that are deactivated by the impurities contained in the added conjugated diene increases, and especially after the completion of polymerization, the coupling efficiency decreases when coupling with a tin compound, etc., resulting in rolling friction resistance. The characteristics are not improved, which is not preferable.

The reaction (treatment) with the polyfunctional coupling agent is not particularly limited, but it is carried out at a temperature not higher than the ultimate temperature of polymerization. The reaction time varies depending on the kind of the polyfunctional coupling agent, but is within 3 hours, usually within 1 hour.

The copolymer of the present invention may be used alone or in an amount of 80% by weight or less of other diene rubbers such as natural rubber, IR, BR and other SB.
Blend with R etc. to add a normal compounding agent for rubber, for example, 100 parts by weight of rubber and 10 parts by weight of filler such as carbon black.
˜120 parts by weight, 0.5 to 5 parts by weight of a sulfating agent and the like can be blended and suitably used for tire applications and various industrial products.

e. EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the Examples is not limited as long as the gist thereof is not exceeded.

In this embodiment, the microstructure is an infrared method (morero method).
I asked. The styrene content was measured by a calibration curve previously obtained using the absorption based on the absorption of the phenyl group at 699 cm ^-1 .

Fracture strength was based on JIS K 6301 tensile strength.

For the rolling frictional resistance characteristics, the value of tan δ measured at 50 ° C was used. tan δ was measured with a viscoelasticity spectrometer (manufactured by Iwamoto Seisakusho). (Frequency 15Hz). Tan δ at 50 ℃
The smaller the value of, the better the rolling friction resistance characteristics.

Wet skid resistance and ice skid resistance were measured using a skid tester manufactured by Stanley.

Wet skid resistance is room temperature, Ice skid resistance is −
It was measured at 10 ° C.

Examples-1 to 10 and Comparative Examples-1 to 7 [Preparation of Polymer A] Cyclohexane was added to a reactor of 5 replaced with nitrogen with 2500
g, 385 g of butadiene, 100 g of styrene, 0.25 g of ethylene glycol dibutyl ether were charged, the temperature was set to 20 ° C., and 0.30 g of n-butyl lithium was charged, and polymerization was carried out under adiabatic condition. Polymerization conversion rate of initial charge monomer is 96%
At the time (the temperature of the polymerization system reached 80 ° C.), 15 g of butadiene was continuously added for 5 minutes. 15 minutes after the addition, when the reaction addition rate reached almost 100%, 2,6-di-t-butylcatechol was added as an anti-aging agent to the polymer 1
0.5 part by weight was added to 00 parts by weight, and the mixture was dissolved and dried by a conventional method.

The vinyl bond content of the butadiene part of the obtained copolymer was 48.
% Bound styrene content 20% by weight, Mooney viscosity Was 38.

Moreover, as a result of analyzing the obtained copolymer by ozonolysis-gel permeation chromatograph, the long chain block content of styrene in which 5 or more styrenes were continuously bonded was 5% or less. The results of measuring the differential styrene content and differential vinyl content percentage of the copolymer with respect to the polymerization conversion rate during the polymerization reaction are shown in Fig. 1. The differential styrene content percentage and the differential vinyl content percentage are the polymerization conversion ratio 3
The polymer was sampled every ~ 5% and determined by the infrared method.

[Preparation of Polymer B]

Polymerization was carried out with the same formulation as polymer A. After the polymerization conversion rate reached almost 100%, 0.2 mol of tin tetrachloride was added to 1 mol of n-butyllithium. Then, the solution was dissolved and dried by a conventional method. Of the obtained polymer Was 64. The vinyl bond content, the amount of bound styrene, and the amount of block bound styrene of the butadiene portion were the same as those of the polymer A.

[Preparation of Polymer C]

 Polymerization was carried out with the same formulation as polymer A.

After the reaction addition rate reached almost 100%, 1 mol of tolylene diisocyanate was added to 1 mol of n-butyllithium. Of the obtained polymer Was 55.

The vinyl bond content, the amount of bound styrene, and the amount of block bound styrene in the butadiene portion were the same as those of the polymer A.

[Preparation of Polymer D]

Cyclohexane was added to 2500 in the reactor which was replaced with nitrogen.
g, 400 g of butadiene, 100 g of styrene, 0.25 g of ethylene glycol dibutyl ether were charged, 0.30 g of n-butyllithium was charged at a temperature of 20 ° C., and polymerization was carried out under adiabatic condition. The polymerization temperature reached 85 ° C. After the reaction conversion reached almost 100%, the same post-polymerization treatment as that for the polymer A was carried out without adding butadiene. The vinyl bond content of the butadiene part of the obtained polymer is 47%.
And the amount of bound styrene is 20% by weight, Was 45.

The amount of block-bonded styrene was 25%.

[Preparation of Polymer E]

Polymerization was carried out using 12.5 g of tetrahydrofuran in place of ethylene glycol dibutyl ether in the polymer D formulation.

The same treatment as in Polymer A was performed.

The vinyl bond content of the butadiene part of the obtained polymer was 48.
%Met.

The amount of block-bonded styrene was 5% or less.

[Preparation of Polymers F to P]

Polymerization was carried out under adiabatic conditions according to the formulations shown in Table-2. Solvent amount, total monomer amount, n-butyllithium amount is polymer A
Same as. When the predetermined reaction conversion rate was reached, butadiene was added in a predetermined amount for 5 to 10 minutes. The reaction conversion reached almost 100% within 15 minutes after the addition. Polymers F, G, and J-P that perform the coupling reaction contain tin tetrachloride in n-
0.2 mol was added to 1 mol of butyllithium. Then, an antiaging agent (2.6 di-t-butyl catechol) was added in a predetermined amount. Then, it was dissolved and dried. Table 3 shows the Mooney viscosity of the obtained polymer, the vinyl bond of the butadiene part, the amount of bound styrene, and the amount of block bound styrene.

Example-10 A copolymer component consisting of 60% by weight of polymer B and 40% by weight of natural rubber was kneaded and vulcanized at the same time as in Example-1 according to the compounding formulation of Table-1, and the results of physical property evaluation are shown in Table-4. Indicated.

Examples-1 to 10 have tensile strengths higher than Comparative Examples-1 to 7,
Wet skid resistance characteristics, Ice skid resistance characteristics,
Excellent balance of rolling friction resistance characteristics.

The comparative example using the polymer without addition of butadiene has a large rolling friction resistance and is inferior in fuel consumption characteristics, and the comparative example using a polymer not using polyether or polyacine is shown in FIG.
Is inferior in ice kid and rolling friction resistance characteristics.

Comparative Examples -4 and 5 in which the polymerization addition rate when adding butadiene was out of the range of the present invention contained a large amount of long chain block polystyrene, and Comparative Example 5 in which the addition amount of butadiene was large, the coupling efficiency was high. Low rolling friction resistance and poor fuel economy. Comparative Example 6 has a small temperature rise range and a small distribution of vinyl bonds, and thus has poor balance of wet skid and ice skid characteristics.

f. Action The conjugated diene-based copolymer produced by the method of the present invention has a vinyl content at an elevated temperature in the presence of a polyether or a tertiary polyamine with an organolithium initiator until the polymerization conversion exceeds 90%. Since the aromatic compound and the conjugated diene compound are copolymerized, the terminal segment of the polymer becomes a copolymer segment (A) having a relatively high content of 1,2 and / or 3,4 bonds at random. As the polymerization temperature increases, the action effect of the polyether or the tertiary polyamine (random effect, the effect of increasing 1,2 and / or 3,4 bonds) decreases, so that the vinyl aromatic compound content gradually decreases, In addition, the copolymer segment (B) has a low content of 1,2 and / or 3,4 bonds. Next, after the polymerization conversion rate of 90% was reached, the content of vinyl aromatic compounds in the monomer was high, so random or continuous addition of conjugated diene compounds from the outside into the polymerization system It becomes a copolymer segment (C) having a high vinyl aromatic compound content.

Thus, the conjugated diene-based copolymer of the present invention is (A)-(B)-
Although it is a (C) type block copolymer, the glass transition temperature of each segment increases in the order of (B) <(A) <(C). Furthermore, between (A)-(B) and (B)-(C) segments are (A) and (B), respectively.
And a glass transition temperature intermediate between (B) and (C) exists.

g. The effect of the invention, the conjugated diene-based copolymer obtained by the method of the present invention,
Since the polymer chain also includes polymer segments with a low glass transition temperature to polymer segments with a high glass transition temperature, the temperature dispersion peak of tan δ of the vulcanizate is wide and has excellent wet skid characteristics, ice skid characteristics, and fracture strength. Since it does not contain a (vinyl aromatic compound) block polymer, it also has excellent rolling friction resistance.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the differential styrene content percentage and the differential vinyl content percentage of the copolymer with respect to the polymerization conversion rate during the polymerization reaction.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display part // (C08F 236/04 212: 06)

Claims (1)

[Claims] 1. A monomer mixture composed of 5 to 35 parts by weight of a vinyl aromatic compound and 95 to 65 parts by weight of a conjugated diene compound is polymerized in a hydrocarbon solvent with an organolithium compound as an initiator to give 1, When a conjugated diene-based copolymer containing 20 to 70% in total of 2 bonds and 3,4 bonds is produced, the polymerization initiation temperature is -10 to 50 in the presence of a polyether or a tertiary polyamine.
℃, the maximum polymerization temperature reached 60 ~ 120 ℃, the difference between the maximum polymerization temperature reached and the polymerization initiation temperature was at least 40 ℃ or more, the polymerization was carried out at an elevated temperature, and the polymerization conversion reached a range of 90 to 99%. Then, 1 to 5 parts by weight of the conjugated diene compound is added continuously or intermittently to 100 parts by weight of the monomer mixture,
A method for producing a conjugated diene-based copolymer, which comprises further polymerizing and terminating the polymerization with a polyfunctional coupling agent.