JPS62220543A - Diene rubber composition - Google Patents

Abstract

PURPOSE:A composition suitable as rubber for tire material having improved wear resistance, breaking strength and hysteresis loss characteristics, obtained by blending specific styrene/conjugated diene copolymer rubber with carbon black and a vulcanizing agent. CONSTITUTION:(A) 100pts.wt. blend rubber containing 30-100wt% styrene- conjugated diene copolymer rubber which is obtained by copolymerizing styrene with a conjugated diene in a hydrocarbon solvent in the presence of an organolithium compound, adding >=three coupling agents to the reaction sites and has 20-120 Mooney viscosity, wherein average total styrene content is 3-50wt%, vinyl bond content of butadiene part is <30wt%, branched copolymer content is >=20wt%, the amount of block having high bond methylene content (twice average bond amount) is 5wt% and block with low bond styrene content is contained is blended with (B) 10-120pts.wt carbon black and (C) 0.5-5pts.wt. vulcanizing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Application Field The present invention relates to a styrene-butadiene copolymer rubber composition having excellent abrasion resistance, breaking strength and hysteresis loss characteristics, particularly a rubber suitable as a rubber for tire materials. Regarding the composition.

b. Conventional technology (
'In recent years, with the demand for lower fuel consumption for automobiles, there has been a strong demand for materials with low hysteresis loss as rubber for tire materials. Therefore, rubbers such as natural rubber, cis 1,4 polyisoprene, low cis 1.4 or high cis 1,4-polybutadiene have come to be used as rubber materials with low hysteresis loss, but Styrene-butadiene copolymers are still used as rubber materials for tires because of problems in terms of strength and the like.

Conventional styrene-butadiene copolymers include styrene-butadiene copolymers obtained by emulsion polymerization and styrene-butadiene copolymers obtained using organolithium compounds as initiators, but because of their large hysteresis loss, rubber for tires The proportion of its use as a material was limited. For this reason, regarding styrene-butadiene copolymer,
A styrene-butadiene copolymer with low hysteresis loss has been desired.

Recently, styrene has significantly improved hysteresis loss.
As a butadiene copolymer, as described in JP-A No. 57-55912, etc., the bond at the branched portion is tin-
Branched styrene-butadiene copolymers comprising butadienyl bonds are known.

However, in order to reduce hysteresis loss, these copolymers are essentially random styrene-butadiene copolymers obtained by polymerizing in the presence of ether or tertiary amine using an organolithium compound as an initiator. It is a copolymer having a structure in which the vinyl content of the butadiene moiety exceeds 50%.

``For this reason, properties such as wear resistance and breaking strength are not necessarily sufficient.

Furthermore, JP-A-59-24702 discloses that a styrene-butadiene copolymer with excellent wear resistance, fracture strength, and hysteresis loss characteristics can be obtained by using a specific branched polymer with a low vinyl content. . However, with this copolymer, when trying to achieve a level that satisfies the fracture strength and hysteresis loss characteristics, the abrasion resistance becomes poor, and there is a limit to achieving a balance among the three characteristics.

Copolymers having a similar morphology to the styrene-butadiene copolymer of the present invention are disclosed in JP-A-54-62248 and JP-A-54-56.
It is proposed in No.-143209 and No. 60-8310. However, since the copolymer has a high vinyl content in the butadiene moiety, the abrasion resistance, fracture characteristics, and hysteresis loss characteristics are not sufficiently improved.

JP-A-57-165445 proposes that hysteresis loss characteristics and abrasion resistance can be improved by using an AB type branched copolymer. However, although the abrasion resistance of this copolymer is improving compared to conventional random type copolymers, it is still unsatisfactory from the viewpoint of the balance between fracture strength and abrasion resistance.

C1 Problems to be Solved by the Invention The present inventors have conducted intensive studies to obtain a styrene-butadiene copolymer with excellent wear resistance, fracture strength, and hysteresis loss characteristics, and as a result, have arrived at the present invention.

Means for Solving the D8 Problems, That is, the present invention involves copolymerizing styrene and a conjugated diene in a hydrocarbon solvent using an organic lithium compound as a polymerization initiator, and then copolymerizing a cup containing three or more reactive sites. Mooney viscosity (obtained by adding a ring agent)
MLl and 4.1°. 'C) In the styrene-conjugated diene copolymer rubber of 20 to 120, i) the average bound styrene content is 3 to 50% by weight, ii) the vinyl bond content of the butadiene moiety is less than 30%, and iii ) the branched copolymer content is 20% by weight or more, and iv) the copolymer rubber is a random copolymer block (A) with a high bound styrene content and a random (co)polymer block with a low bound styrene content. (B), and the bound styrene content of block (A) is 2 of the average bound styrene content.
(2) a styrene-conjugated diene copolymer rubber containing block (A) of 5% by weight or more, or a mixture of 30 parts by weight or more of the copolymer rubber and 70 parts by weight or less of other diene rubber; 1 part carbon black per 100 parts by weight of blended rubber
A diene rubber composition containing 0 to 120 parts by weight and 0.5 to 5 parts by weight of a vulcanizing agent is provided.

The above-mentioned styrene-conjugated diene copolymer rubber is a random type rubber having a vinyl bond content of less than 30% in the conjugated diene moiety and an amount of bound styrene that is at least twice the average amount of bound styrene in one molecular chain. It is characterized by containing 5% by weight or more of a styrene-conjugated diene copolymer.

If the vinyl bond content is 30% or more, wear resistance and fracture strength will be poor. A more preferable range of vinyl bond content is 10 to
It is 20%.

If the random type styrene-conjugated diene copolymer portion having an amount of bound styrene that is twice or more the average amount of bound styrene is less than 5% by weight, it is difficult to maintain a balance between wear resistance and fracture strength. The amount of bound styrene in the copolymer portion with a high amount of bound styrene is preferably 10 to 50.
Weight%.

Furthermore, if the amount of bound styrene in the copolymer portion is less than twice the average amount of bound styrene, a balance between wear resistance and fracture strength cannot be maintained.

Random type styrene-conjugated diene copolymer rubber refers to I, M
, Kolthoff et al.'s oxidative decomposition method (J, P, S, Vo
The block polystyrene content measured by I P429 (1946) is 10% by weight or less. If the block polystyrene content exceeds 10% by weight, hysteresis loss will increase, which is undesirable.

Another important feature of the present invention is that the copolymer rubber contains at least 20% by weight, more preferably at least 30% by weight, of a branched polymer. If the branched polymer content is less than 20% by weight, the fracture properties and wear resistance will not be sufficiently improved.

The bound styrene content of the styrene-conjugated diene copolymer rubber of the present invention is 3 to 50% by weight, more preferably 10 to 4% by weight.
It is 0% by weight.

If the bound styrene content is less than 3% by weight, the breaking strength is poor, and the
If it exceeds % by weight, wear resistance and hysteresis loss characteristics will be poor.

The molecular weight of the styrene-conjugated diene copolymer rubber of the present invention is 20 to 12 in Mooney viscosity (ML+-a, t...℃).
It is preferable that the amount is in the range of 0 in order to maintain desired processability and physical properties. When the Mooney viscosity is less than 20, hysteresis loss and breaking strength are poor. Moreover, if the Mooney viscosity exceeds 120, processability will be poor, which is not preferable.

The styrene-conjugated diene copolymer rubber of the present invention is composed of two block parts (A) and (B) having different microstructures, and the microstructure near the bonding part of each block part is (A). , (B) may have an intermediate microstructure, that is, the physical properties will not be impaired even if the structure gradually changes from the (A) block microstructure to the (B) block microstructure. do not have.

The styrene-conjugated diene copolymer rubber of the present invention is produced by the method described below.

When copolymerizing styrene and conjugated diene using an organolithium compound as a polymerization initiator in a hydrocarbon solvent, the low copolymerization reactivity of styrene is used to increase the concentration of styrene in the polymerization system to a certain level. At this point, the conjugated diene is polymerized while being added continuously or intermittently, and after the polymerization is completed, a coupling agent is added to form a branched polymer, thereby producing the styrene-conjugated diene copolymer of the present invention. You can get rubber.

Still another method is to generate a random styrene-conjugated diene copolymer by the method shown in JP-A-56-143209 and JP-B-3B-2394, and then further conjugate it with styrene. The desired copolymer can be obtained by polymerizing in the same manner while changing the feed ratio of diene and performing a coupling reaction.

In the above polymerization, tetrahydrofuran 1. Dimethoxybenzene, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, dibutyl ether, triethylamine, pyridine, N, N
, N'N' -tetramethylamine, or other ether or tertiary amine can be added to improve the polymerization activity and the randomness of styrene.

The above polymerization is carried out under isothermal polymerization or temperature-programmed polymerization conditions in the range of 0 to 120°C.

Hexane, heptane, cyclohexane as hydrocarbon solvents used in polymerization? , benzene, xylene, methylcyclopenkune and mixtures thereof.

As an organic lithium compound, n-butyllithium, 5e
c-butyllithium, tert-butyllithium, propyllithium, phenyllithium, etc. are used. The amount of organolithium compound is 0 per 100 parts by weight of monomer.
．． It is used in a range of 0.02 to 0.2 parts by weight.

Further, the conjugated diene added at the final stage of polymerization is used in a wide range of 0.2 to 40 parts by weight based on 100 parts by weight of the total monomers.

Coupling agents used in the production of branched styrene-conjugated diene copolymer rubber, that is, in the coupling reaction, include silicon tetrachloride, methyl silicon trichloride, tin tetrachloride, methyl tin trichloride, (RCOO÷, ~4SnRo - Polyepoxy compounds such as tin maleate, epoxidized soybean oil, polyisocyanate compounds such as polymeric type diphenylmethane diisocyanate, polyaldehyde compounds, polyketone compounds, polyester compounds,
Polyanhydride compounds, polyimine compounds, etc.
There are polyfunctional coupling agent compounds having at least three reactive sites listed in No. 7.

The coupling agent is used in an amount of 0.2 to 2 equivalents per 1 equivalent of a lithium atom at the end of the polymer.

The coupling reaction is carried out at a temperature ranging from 50 to 120°C.

The styrene-conjugated diene copolymer rubber of the present invention can be used alone or in combination with 30 parts by weight or more of the rubber, natural rubber, cis 1゜4-polyisoprene, emulsion polymerized styrene-butadiene copolymer, solution polymerized styrene-butadiene copolymer. , high cis 1,
4-polybutadiene, low cis 1,4-polybutadiene,
It is used by blending with 70 parts by weight or less of one or more diene rubbers selected from ethylene propylene diene copolymers, oil extended if necessary, and ordinary compounding agents for vulcanized rubber are added. Vulcanization is applied to tire applications such as treads, sidewalls, bead parts, anti-vibration rubber,
It can be used for belts, hoses, window frames, and other industrial products. If the amount is less than 30 parts by weight of the styrene-conjugated diene copolymer rubber, the effects of the present invention cannot be obtained.

The styrene-conjugated diene copolymer rubber of the present invention can also be used as a pace rubber for impact-resistant polystyrene, impact-resistant resins made of acrylonitrile/styrene/rubber, and the like.

e. Examples The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the extent that it does not go beyond the gist of the present invention.

In addition, various measurements were performed according to the following methods.

Tensile properties as an index of fracture strength are JIS K 63
Measured according to 01. For the hysteresis loss characteristic, tan δ was used as an index. tan δ is a mechanical spectrometer manufactured by Rheometrics (frequency 15
11z).

Abrasion resistance was measured using a Pico abrasion tester.

The microstructure of the butadiene moiety of the styrene-butadiene copolymer was determined by an infrared method (Morello method).

The content of bound styrene was determined from a previously determined calibration curve using an infrared method based on absorption by phenyl groups at a wave number of 699 am-'.

The proportion of the branched styrene-butadiene copolymer in the styrene-butadiene copolymer was determined from the ratio of the area of the high molecular weight side peak of gel permeation chromatography (GPC) to the total peak area.

The ratio of block polystyrene to the total bound styrene content in the styrene-butadiene copolymer is determined in 1. above. M,
It was determined by the method of Kolthoff et al.

Examples and Comparative Examples Polymer A Cyclohexane 25 was placed in a reactor with an internal volume of 51 and equipped with a stirrer.
00g, 1. 3-butadiene 135g, styrene 1
After charging 5g and adjusting the temperature inside the reactor to 80℃,
0.34 g of n-butyllithium was charged and polymerization was started.

Immediately after the start of polymerization, 150 g of butadiene was continuously added to 90
It was added over a period of minutes. After the polymerization conversion rate reached 99% or more, 0.0% of ethylene glycol dibutyl ether was added.
Immediately after adding 5 g of styrene, 100 g of styrene, and 50 g of butadiene, polymerization was carried out while continuously adding 50 g of butadiene. The addition was completed after 30 minutes, and the polymerization conversion rate was 9.
After reaching 9%, 0.22 g of tin tetrachloride was added as a coupling agent. The analysis results of the resulting polymer are shown in Table 1.

2500 g of cyclohexane in a reactor with a stirrer of Polymer °B 51
After charging 300 g of 1,3-butadiene and adjusting the temperature inside the reactor to 80°C, 0.34 g of n-butyllithium was charged.
g was charged and polymerization was carried out. Immediately after the polymerization conversion rate reached 99% or more, 0.5 g of ethylene glycol dibutyl ether, 100 g of styrene, and 50 g of butadiene were newly added, and then polymerization was carried out while continuously adding 50 g of butadiene. After the polymerization conversion rate reached 99% or more, add 0.22 g of tin tetrachloride as a coupling agent.
Added. The analysis results of the obtained polymer are shown in Table-1.

Polymer C From the start of the first stage polymerization, add 0.7% of tetrahydrofuran.
Polymerization was carried out using the same recipe as Polymer B without adding 5g of ethylene glycol dibutyl ether. The analysis results of the obtained polymer are shown in Table-1.

Add 2500 g of cyclohexane to a reactor with a stirrer for Polymer D 51.
, 1.3-butadiene 150g, styrene 38. was charged, and polymerization was started in the same manner as Polymer A. Immediately after the start, 187 g of butadiene was added continuously over 90 minutes.

After the polymerization conversion rate reached 99% or more, 0.5 g of ethylene glycol dibutyl ether and 62.0 g of styrene were added.
5g.

Immediately after adding 30 g of butadiene, add 32 g of butadiene.
．． Polymerization was carried out while continuously adding 5 g. Coupling was then carried out with tin tetrachloride in the same manner as for Polymer B. The analysis results of the obtained polymer are shown in Table-1.

Polymer E Polymerization was carried out using the same recipe as Polymer A. 0.9 g of polymeric type diphenylmethane diisocyanate was added as a coupling agent. The analysis results of the obtained polymer are shown in Table-1.

Add 2500 g of cyclohexane to a reactor with a stirrer for Polymer F 51.
, 100 g of 1,3-butadiene, and 60 g of styrene were charged, and the temperature inside the reactor was adjusted to 80° C., and then 0.34 g of n-butyllithium was charged to start polymerization. Immediately after the start of polymerization, 140 g of butadiene was continuously added over 120 minutes. After the polymerization conversion rate reached 99% or more, 0.5% of ethylene glycol dibutyl ether was added.
g.

Immediately after adding 70 g of styrene and 60 g of butadiene, polymerization was carried out while continuously adding 70 g of butadiene. After the polymerization conversion rate reached 99%, 0.22 g of tin tetrachloride was added as a pulling agent. The analysis results of the obtained polymer are shown in Table-1.

Polymer G Polymer G was obtained using a polymerization method similar to that of Polymer B.

The analysis results of the obtained polymer are shown in Table-1.

Polymer H A polymer was obtained by the same polymerization method as Polymer C except that 1.5 g of tetrahydrofuran was used. The analysis results of the obtained polymer are shown in Table-1.

Polymer ■ 2500 g of cyclohexane in a 5 g reactor with a stirrer
, 60g of 1,3-butadiene was charged, and the temperature inside the reactor was adjusted to 80°C, and then 0.34g of n-butyllithium was added.
was charged to start polymerization. Immediately after the polymerization conversion rate reached 99% or more, 0.5 g of ethylene glycol dibutyl ether, 80 g of butadiene, and 260 g of styrene were added, and then polymerization was carried out while continuously adding 100 g of butadiene. After the polymerization conversion rate reached 99% or more, 0.22 g of tin tetrachloride was added as a coupling agent. The analysis results of the obtained polymer are shown in Table-1.

Polymer J Polymerization and camping reaction were carried out using a similar recipe to Polymer C, except that 0.5 g of ethylene glycol was added during the second stage polymerization. The analysis results of the obtained polymer are shown below.
Shown in 1.

Polymer K Polymerization and camping reaction were carried out using the same recipe as Polymer A except that the amount of n-butyllithium used was 0.30 g and the amount of tin tetrachloride was changed to 0.05 g. The analysis results of the obtained polymer are shown in Table-1.

Polymer L: 2500 g of cyclohexane in a reactor with internal volume 51 and equipped with a stirrer; 1. After charging 200 g of 3-butadiene, 100 g of styrene, and 0.5 g of tetrahydrofuran and adjusting the temperature inside the reactor to 80° C., 0.34 g of n-butyllithium was charged to start polymerization. Immediately after the start of polymerization, 200 g of butadiene was continuously added over 90 minutes. After the polymerization conversion rate reached 99%, 0.22 g of tin tetrachloride was added as a coupling agent. The analysis results of the obtained polymer are shown in Table-1.

Polymers M, N, O1P Polymers M, N, 0, and P were prepared using the same polymerization method as Polymer A, but with different monomer charging ratios.

The analysis results of the obtained polymer are shown in Table-1.

Table 3 shows the physical property evaluation results of the polymers obtained in the above Examples and Comparative Examples.
It is clear that the composition has excellent properties in terms of wear resistance, fracture strength, and hysteresis loss characteristics as compared to the comparative example.

e0 Effects of the Invention According to the present invention, a styrene-butadiene copolymer composition having excellent wear resistance, fracture strength, and hysteresis loss characteristics can be obtained.

Table-2 Polymer 11AF Carpon Plank Stearic Acid nO Anti-Aging Agent 81ONA *+ ,, 7p $! Accelerator DPG *'II DM 4 sulfur ml N-phenyl-N'-isopropyl-2 bottles 2
Sodium diphthyldithiocarba *3 Diphenylguanidine 4 Parts by weight of dibensothiazyl disulfide 0, 8 0, 6 1, 2 1, 5 - Phenyl diamine mate

Claims (2)

[Claims] (1) In a hydrocarbon solvent, styrene and conjugated diene are copolymerized using an organolithium compound as a polymerization initiator, and then 3
Mooney viscosity (ML_1_+_4_
,_1_0_0°C) 20 to 120 styrene-conjugated diene copolymer rubber, i) the average bonded styrene content is 3 to 50% by weight, ii) the vinyl bond content of the butadiene moiety is less than 30%, iii) the branched copolymer content is 20% by weight or more,
iv) The copolymer rubber consists of a random copolymer block (A) with a high bound styrene content and a random copolymer block (B) with a low bound styrene content, and the bound styrene content of the block (A) is the average bound styrene content. and v) a styrene-conjugated diene copolymer rubber containing 5% by weight or more of block (A) alone or 30 parts by weight or more of the copolymer rubber and other diene rubber 70
10 to 120 parts by weight of carbon black and 0.5 to 5 parts by weight of vulcanizing agent per 100 parts by weight of the blended rubber.
A diene rubber composition comprising parts by weight. (2) The rubber composition according to claim (1), wherein the vinyl bond content of the butadiene moiety is less than 20%.