JPH0611766B2 - Vinyl aromatic hydrocarbon-conjugated diolephine copolymer and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a copolymer of a vinyl aromatic hydrocarbon having improved processability and a conjugated diolefin, and a method for producing the same.

b. Conventional technology In order to meet the demands for driving safety and low fuel consumption of automobiles,
As a rubber material for tire treads with excellent properties such as breaking strength, wet skid resistance, hysteresis loss, etc.
A butadiene-based polymer having a high vinyl content in the butadiene portion and containing a branched polymer has been proposed. For example, there are JP-A-57-55912 and JP-A-57-87407.

c. Problems to be Solved by the Invention However, when these butadiene-based polymers are used alone, the roll wrapping property of the carbon black kneaded product is poor, the extruded surface of the carbon kneaded product is poor, etc. However, it had to be blended with other rubbers and used.

Focusing on the molecular weight distribution, the present inventors have diligently studied a copolymer of a vinyl aromatic hydrocarbon and a conjugated diolefin containing a certain amount of a low molecular weight polymer in a specific range, and as a result of the study, In a copolymer of an aromatic hydrocarbon containing a ringed polymer and a conjugated diolefin, a vinyl aromatic compound in a specific range is obtained by a so-called monomer addition two-step polymerization method in which the addition of the monomer to the polymerization system is divided into two steps. A copolymer of a vinyl aromatic hydrocarbon on a branch and a conjugated diolefin containing a specific range of a low molecular weight polymer containing a specific range of a range of hydrocarbons has characteristics such as hysteresis loss characteristics and fracture characteristics. The present invention has been accomplished by finding that roll winding property and extruded skin can be improved without impairing the above.

An object of the present invention is to improve workability such as roll wrapping property and extruded surface without impairing properties such as hysteresis loss property, breaking property, wet skid resistance and the like.

d. Means for Solving Problems In order to solve the above problems, the present invention provides a branched copolymer of a vinyl aromatic hydrocarbon and a conjugated diolefin using an organolithium initiator, wherein Polymer has vinyl aromatic hydrocarbon content of 10-40% by weight, vinyl bond content of conjugated diolefin part is 30-90%
The proportion of the coupled branched copolymer is 30% by weight or more, and the content of the component having a molecular weight of less than 100,000 in terms of polystyrene in the molecular weight distribution measured by GPC is 5 to 20% by weight.
And the vinyl aromatic hydrocarbon content of the component is 0-10%
The present invention provides a copolymer of vinyl aromatic hydrocarbon and a conjugated diolefin and a method for producing the same.

Examples of the vinyl aromatic hydrocarbon used in the conjugated diolefin polymer of the present invention include styrene and P-
Methylstyrene, vinyltoluene, P-ethylstyrene, vinylnaphthalene and the like can be mentioned, with preference given to styrene. As a result, the vinyl aromatic hydrocarbon content is 10 to 40% by weight, preferably 10 to 30% by weight in order to balance the breaking strength and the hysteresis loss characteristics. When the content of the bound vinyl aromatic hydrocarbon exceeds 40% by weight, the hysteresis loss property and the breaking strength are deteriorated, which is not preferable. If it is less than 10% by weight, the breaking strength is poor. The bound vinyl aromatic hydrocarbons in the copolymer can be synthesized by the oxidative decomposition method “J. Polymer Sci. Vol.
(1964) ”, it is preferable that the content of the block polymer of vinyl aromatic hydrocarbon in all the bonded vinyl aromatic hydrocarbons is 10% or less in a random state. The bound vinyl aromatic hydrocarbon may or may not be evenly distributed along the molecular chain.

Examples of the conjugated diolefin used in the present invention include 1,
Examples thereof include 3-butadiene, isoprene and piperidine, with 1,3-butadiene being preferred.

The conjugated diolefin part of the conjugated diolefin polymer of the present invention has a vinyl bond content of 30 to 90%, preferably 35 to 75%.
Is. If the vinyl content is less than 30%, the wet skid properties are poor, and if it exceeds 90%, the breaking strength is poor, which is not preferable.

Gel permeation chromatograph (GPC) of a copolymer of a vinyl aromatic hydrocarbon and a conjugated diolefin of the present invention
The molecular weight distribution curve measured by the method is a trimodal type and has a high molecular side peak (coupling polymer peak) and two low molecular side peaks (uncompressed polymer peak and first stage weight). It is composed of three peaks (the peak of the deactivated product of the coalescence).

The ratio of the coupled polymer can be determined from the ratio of the peak area on the high molecular weight side to the total area of the molecular weight distribution curve by gel permeation chromatography (GPC).

The proportion of the coupled polymer in the copolymer of vinyl aromatic hydrocarbon and conjugated diolefin is 30% by weight or more,
If it is less than 30% by weight, the hysteresis loss property and the fracture property are inferior, which is not preferable.

The characteristic feature of the vinyl aromatic hydrocarbon-conjugated diolefin copolymer of the present invention is that it has a molecular weight of 1 in terms of polystyrene by GPC.
The proportion of the polymer having a conjugated diolefin of not more than 00,000 as a main component is in the range of 5 to 20% by weight.

When the polymer having a molecular weight of 100,000 or less in terms of polystyrene by GPC is present in an amount of more than 20% by weight, the hysteresis loss property is inferior. On the other hand, if it is less than 5% by weight, the workability is poor. Further, when the vinyl aromatic hydrocarbon content of 10% by weight or more is contained in the low molecular weight component having a molecular weight of 100,000 or less, the hysteresis loss characteristic is poor. The vinyl aromatic hydrocarbon content in the low molecular weight component was determined by an infrared method by collecting a component having a molecular weight of 100,000 or less by GPC.

The vinyl aromatic hydrocarbon-conjugated diolefin copolymer of the present invention has a Mooney viscosity (ML _{1 + 4} 100 ° C.) of 30 to 10
0 is preferable. When the Mooney viscosity is less than 30, the hysteresis loss property is poor, and when it exceeds 100, the workability is poor, which is not preferable.

The vinyl aromatic hydrocarbon-conjugated diolefin copolymer of the present invention having the above characteristics is manufactured by the following method.

That is, using an organolithium compound as an initiator in a hydrocarbon solvent in the presence of a Lewis base, i) first, a mixture of a vinyl aromatic hydrocarbon and a conjugated diolefin having a mixing ratio of 0 to 10/100 to 90 is used. After 10 to 70% by weight of the total amount of the monomer is polymerized and the polymerization is substantially completed, ii) Less than the polymerization activity deactivator is added in an amount of 0.2 equivalent or less with respect to the amount of the organolithium initiator used to reduce the activity. After partial inactivation, iii) the remaining monomers are added and polymerized, and after the polymerization is substantially completed, iv) coupling is performed with a coupling agent.

Examples of the hydrocarbon solvent used in the polymerization reaction of the present invention include pentane, hexane, heptane, cyclohexane, methylcyclopentane, benzene, toluene, xylene, and the like.
It is used in the range of 0.5 to 20 parts by weight per part by weight.

As the organic lithium initiator, ethyl lithium, propyl lithium, butyl lithium, pentyl lithium, 1,
4-dilithiobutane, 1,5-dilithiopentane and the like can be mentioned. The amount of organolithium initiator used depends on the monomer
It is in the range of 0.2 to 20 millimoles per 100 grams.

It also improves polymer randomness and vinyl bond content.
A suitable amount of Lewis base is usually used in combination with the organolithium initiator to adjust to 30-90%.

Examples of the Lewis base used here include ether and tertiary amine, and specifically, for example, diethyl ether, dibutyl ether, tetrahydrofuran, 2-methoxytetrahydrofuran, 2-methoxymethyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl. Ether, ethylene glycol dibutyl ether, triethylamine, viridine,
N, N, N ', N'-tetramethylethylenediamine,
N, N, N ', N'-tetraethylethylenediamine,
Examples thereof include N-methylmorpholine and triethylenediamine. The amount of Lewis base used is in the range of 0.05 to 1000 mol per mol of the organolithium initiator.

As the polymerization active terminal deactivator used in the present invention, compounds having active hydrogen such as water, alcohols or phenols are preferably used. As alcohols, methanol, ethanol, propyl alcohol, butanol,
Examples thereof include ethylene glycol, propylene glycol and glycerin. Examples of phenols include phenol, cresol, α, β-naphthanol, nonylphenol, t-butyl-hydroxytoluene and the like. Water, methanol, phenol and t-butyl-hydroxytoluene are particularly preferable.

The deactivator may be added alone into the polymerization system after the completion of the polymerization of the monomer added in the first step, or may be added as a mixture with the monomer and the solvent added in the second step. The amount of the quenching agent added is 0.2 equivalent or less of the amount of the initiator used. If the added amount exceeds 0.2 equivalent, the hysteresis loss characteristic becomes poor.

The coupling agent used in the present invention includes a bifunctional coupling agent such as dibromoethane, a trifunctional or higher-functional polyfunctional coupling agent such as a compound having 3 to 4 halogen atoms or dicarboxylic acid diesters. , Isocyanates can be used.

Examples of the compound having 3 to 4 halogen atoms include
Specifically, silicon tetrachloride, silicon halide compounds such as methyl trichloride, methyltrichlorotin, tetrachlorotin, butyltrichlorotin, octyltrichlorotin, methyltribromotin, octyltribromotin, tetrabromotin, tetra Iodotin, cyclohexyltrichlorotin, phenyltrichlorotin, 1,2
Halogenation of -bis (trichlorostannyl) ethane, 1,2-bis (methyldichlorostannyl) ethane, 1,4-bis (trichlorostannyl) butane, 1,4-bis (methyldichlorostannyl) butane Organic compounds such as tin compounds, tetrabromobenzene and trichlorobenzene can be mentioned.

Specific examples of dicarboxylic acid diesters include dimethyl adipate, diethyl adipate, dioctyl adipate, diethyl fumarate, diethyl ailenate and the like.

Examples of the isocyanates include tolylene isocyanate and tolidine diisocyanate.

Of these, tin halide compounds are preferred.

The coupling reaction is usually carried out under the conditions of a reaction temperature of 0 to 150 ° C. and a reaction time of 1 minute to 20 hours.

The amount of the coupling agent to be used is 0.1-based on the halogen atom per 1 atom equivalent of lithium of the organolithium compound.
It is used in the range of 3.0 equivalents, preferably in the range of 0.2 to 1.5 equivalents.

More preferably, in the case of obtaining a coupling polymer in which the bond of the coupling moiety is a tin-butadienyl bond, immediately before the addition of the tin halide compound, 0.5 to 100 mol, preferably 1 to 100 mol, per 1 atom equivalent of lithium of the organolithium compound is preferable. It is desirable to add 1 to 50 mol of 1,3-butadiene.

The vinyl aromatic hydrocarbon-conjugated diolefin copolymer of the present invention is a homopolymer or natural rubber and high cis 1,4-polyisoprene, emulsion polymerization styrene butadiene copolymer, solution polymerization styrene butadiene copolymer (of the present invention Blended with one or more rubbers of synthetic rubbers such as high cis 1,4-polybutadiene, low cis 1,4-polybutadiene, etc., except for conjugated diolefin-based polymers), known compounding agents, fillers, Blended with process oil, vulcanizing agent, accelerator,
After being vulcanized, it is used as a rubber material for tires such as tire treads, tire sidewalls, tire belt parts, tire beat parts, etc.
Used for hoses, window frames, and other industrial products. Further, it is also used as a base rubber of an impact resistant resin obtained by polymerizing with styrene, styrene, acrylonitrile or the like.

e. Examples Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

In the examples, the bound styrene content was determined by measuring the area of the infrared absorption peak due to the phenyl group at 699 cm ₋₁ and from the calibration curve obtained in advance.

The microstructure of the polybutadiene portion was determined by the infrared method (Morero method).

The impact resilience was measured using a Dunlop trypsometer at a temperature of 50 ° C. so as to serve as an index of hysteresis loss of the tire tread. The larger the value, the better the impact resilience. The tensile properties were measured according to JIS K 6301. Wet skid resistance is measured on indoor wet asphalt road surface using a skid tester manufactured by Stanley, UK,
The results are shown in index form with Example 3 as 100. The larger the index value, the better. Regarding the roll wrapping property of the blend, a winding state at 60 ° C. and a 6 inch roll was observed.

The molecular weight distribution of the polymer of the present invention is from Waters
The measurement was performed under the following conditions using a 244 type GPC and a differential refractometer as a detector.

Column: Toyo Soda column GMH-3, GMH-6, G6000H-6 Mobile phase: Tetrahydrofuran Also, regarding the molecular weight in terms of polystyrene, a monodisperse styrene polymer manufactured by Waters was used, and the peak of the monodisperse styrene polymer was determined by GPC. The molecular weight in terms of polystyrene of the polymer of the present invention was determined using a calibration curve obtained by previously determining the relationship between the molecular weight and the number of GPC counts.

For the roll wrapping property, a 6-inch roll was used, and the quality of the wrapping property of the rubber at 60 ° C. was visually judged.

The extrudability of the formulations was measured by ASTM 2230-77 (Method A).

Example 1 1500 g of cyclohexane in a 10 polymerization reactor equipped with a stirrer,
200 g of 1,3-butadiene, 13.5 g of tetrahydrofuran
Then, the temperature in the polymerization reaction vessel was adjusted to 10 ° C., and 0.65 g of n-butyllithium was added to initiate polymerization.

The highest temperature reached was 50 ° C.

After completion of the reaction, the mixture was cooled to 10 ° C in 30 minutes.

Next, 590 g of 1,3-butadiene with a water content of 5 ppm, 200 g of styrene with a water content of 10 ppm, and cyclohexane with a water content of 5 ppm.
A mixture of 4500 g was added to the polymerization system in 1 minute to start the second stage polymerization.

The polymerization conversion rate became 99% or more 35 minutes after the addition of the monomer, after which 10 g of 1,3-butadiene was added, and after 5 minutes, 0.4 g of tin tetrachloride was added and the coupling reaction was carried out for 30 minutes.

50m cyclohexane solution containing 7g of 2,6-ditertiarybutyl-P-cresol, an antioxidant in the polymer solution
After the addition of the above, the obtained polymer solution was dissolved by steam stripping and dried on a hot roll at 110 ° C. to obtain a styrene-butadiene copolymer.

The properties of the obtained polymer are shown in Table 2.

After kneading with a 250cc Brabender plastomill and 6 inch rolls according to the compounding procedure shown in Table-3
Vulcanization was performed at 0 ° C for 12 minutes.

The properties of the obtained vulcanizate are shown in Table 4.

Example 2 Instead of water in 1,3-butadiene, styrene and cyclohexane in Example 1, 10 ppm of methanol was added,
The same procedure as in Example 1 was carried out except that 5 ppm and 3 ppm were included.

Example 3 In Example 1, 0 g of styrene was used in the first-stage polymerization, and 10 g of styrene was used instead of 200 g of styrene in the second-stage polymerization.
The same procedure as in Example 1 was carried out except that the amounts were changed to g and 190 g.

Comparative Example 1 10 polymerization reactors equipped with a stirrer, 6000 g of cyclohexane
After 790 g of 1,3-butadiene, 200 g of styrene and 54 g of tetrahydrofuran were charged and the temperature in the polymerization reaction vessel was adjusted to 10 ° C, 0.65 g of n-butyllithium was added to initiate polymerization.

The temperature reached 86 ° C in 35 minutes after the initiation of the polymerization, and the polymerization conversion rate became 99% or more. Then, 10 g of 1,3-butadiene was added, and after 5 minutes, 0.40 g of tin tetrachloride was added and the coupling reaction was carried out for 30 minutes. .

Then, the same procedure as in Example 1 was carried out to obtain a vulcanized product.

Table-2 and Table-4 show the evaluation results of various properties.

Comparative Example 2 In Example 1, the first stage 1,3-butadiene 200
g, second stage 1,3-butadiene 590 g, styrene 200 g
Instead of, 1st stage 1,3-butadiene 160g, Sutin 4
0g, second stage 1,3-butadiene 630g, styrene 160g
Example 1 was repeated except that

Comparative Example 3 In Example 1, tetrahydrofuran was added at 13.5% in the first stage.
g, instead of using 40.5 g in the second stage polymerization, 0.4 each
The same procedure as in Example 1 was performed except that g and 1.2 g were used.

Comparative Example 4 Tetrahydrofuran was added at 13.5% in Example 1
g, instead of using 40.5g in the second stage, 90g, 27 respectively
Example 1 was repeated except that 0 g was used.

Comparative Example 5 In Example 1, the second stage polymerization of 1,3-butadiene 59
Instead of 0 g and styrene 200 g, 1,3-butadiene 34
The same procedure as in Example 1 was carried out using 0 g and styrene 450 g.

Comparative Example 6 The procedure of Example 1 was repeated, except that tin tetrachloride (0.04 g) was used instead of tin tetrachloride (0.4 g).

Comparative Example 7 In the same manner as in Example 1, except that the water content in 1,3-butadiene, styrene, and cyclohexane in Example 1 was adjusted to 15 ppm, 20 ppm, and 15 ppm instead of being adjusted to 5 ppm, 10 ppm, and 5 ppm, respectively. I did.

Example 4 In Example 1, 1,3-butadiene 590 having a water content of 5 ppm
g, 200 g of styrene having a water content of 10 ppm, and 4500 g of cyclohexane having a water content of 5 ppm, instead of being added,
Example 1 was repeated except that 590 g of 1,3-butadiene having a water content of 2 ppm, 200 g of styrene having a water content of 3 ppm, and 4500 g of cyclohexane having a water content of 2 ppm were added.

Example 5 In Example 1, 200 g of 1,3-butadiene was obtained by the first-stage polymerization.
Example 1 was repeated except that 180 g of 1,3-butadiene and 20 g of styrene were used instead of.

Example 6 In Example 1, tetrahydrofuran 13.5 was used in the first stage.
g, Example 1 except that 3.7 g and 11.0 g were added, respectively, instead of adding 40.5 g of tetrahydrofuran in the second stage.
I went the same way.

Example 7 Example 1 was repeated except that tin tetrachloride (0.30 g) was added instead of tin tetrachloride (0.40 g).

Example 8 In Example 1, 1,3-butadiene 490 was used in the second stage polymerization.
g and 300 g of styrene were added, and the same procedure as in Example 1 was performed.

Table-3 Rubber 100 Carbon black 50 Highly aromatic oil 10 Zinc white 3 Stearic acid 2 Anti-aging agent 810 NA ¹⁾ 1 Vulcanization accelerator CZ ²⁾ 1.7 1) N-phenyl-N'-isopropyl-P-phenylenediamine 2) N-cyclohexyl-2-benzothiazyl sulfenamide e. Effects of the Invention According to the present invention, workability such as roll wrapping property and extruded skin can be improved without impairing properties such as hysteresis loss property, breaking property and wet skid resistance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mikio Takeuchi 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (72) Inventor Tatsuo Fujimaki 3-2-3 Fujimicho, Higashimurayama, Tokyo Shin Musashino Sky Heights 613

Claims (2)

[Claims] 1. A copolymer of a vinyl aromatic hydrocarbon and a conjugated diolefin using an organolithium initiator, wherein the average bound vinyl aromatic hydrocarbon content of the copolymer is 10 to 40% by weight, and the conjugated The vinyl bond content of the diolefin part is 30 to 90%, and the proportion of the branched branched copolymer is 30% by weight.
Above, gel permeation chromatography (hereinafter GP
The content of the component having a molecular weight of less than 100,000 in terms of polystyrene in the molecular weight distribution measured by C) is 5 to 20% by weight, and the vinyl aromatic hydrocarbon content of the component is less than 10% by weight. A copolymer of a vinyl aromatic hydrocarbon and a conjugated diolefin characterized by the following: 2. An organolithium compound is used as an initiator in a hydrocarbon solvent in the presence of a Lewis base, i) The ratio of vinyl aromatic hydrocarbon to conjugated diolefin is 0-10 / 100-90. The monomer mixture is added in an amount of 10 to 70% by weight based on all the monomers, and after the polymerization reaction is substantially completed, ii) a polymerization-active end-activator is added in an amount of 0.2 equivalent to the amount of the organolithium initiator used. The following is added to partially deactivate the active end, and then iii) the remaining monomer is added and polymerized, and after the polymerization is substantially completed, iv) the coupling agent is finally added to form a branched chain. Characterized by polymerizing copolymer, vinyl aromatic hydrocarbon content is 10-40% by weight, vinyl bond content of conjugated diolefin part is 30-
90%, 5-20% of components having a molecular weight of less than 100,000 in terms of polystyrene measured by GPC, and vinyl aromatic hydrocarbon content of the components is less than 10% by weight. For producing a copolymer of styrene and a conjugated diolefin.