KR101700012B1 - Modified diene polymer and composition comprising the same - Google Patents

Abstract

The present invention relates to a vinyl aromatic-conjugated diene-based copolymer which is obtained by introducing a functional monomer which is converted into a carboxylic acid or anhydride into a terminal of the vinyl aromatic-conjugated diene copolymer under thermal or acid catalysis and has an enhanced compatibility with a hydroxy group on the surface of the inorganic filler Thereby providing a modified diene polymer excellent in affinity for an inorganic filler. When the modified conjugated diene-based copolymer according to the present invention is used for a tire material, the affinity with the inorganic filler is improved and the balance between low hysteresis loss and wet skid property, which are main characteristics required in a tire, Effect can be obtained.

Description

MODIFIED DIENE POLYMER AND COMPOSITION COMPRISING THE SAME [0002]

More particularly, the present invention relates to a modified conjugated diene polymer and a composition containing the modified conjugated diene polymer. More particularly, the present invention relates to a modified conjugated diene polymer which is hydrolyzed under heat or an acid catalyst to at least one of the starting end and the terminal end of the polymer chain to form a carboxyl group or an anhydride ), Which is excellent in storage stability and is excellent in affinity with a polar inorganic additive such as silica, and a composition containing the same.

Recently, as interest in environmentally friendly materials and energy saving materials has increased, modified conjugated diene-based polymer materials in which functional chemicals are introduced into diene-based polymers are used in various applications. Particularly, there is a growing demand for development of material technology capable of improving braking performance and fuel economy by applying such modified conjugated diene polymer to automobile tires. Previously, styrene-butadiene rubber (ESBR) obtained by emulsion polymerization was used as a material used for tire tread, and a material having enhanced elasticity through blending and vulcanization process was used as an inorganic additive such as carbon black and sulfur. However, it is difficult to control the molecular weight and the molecular weight distribution of the ESBR material during the polymerization process, and the control of the microstructure of the polymer is limited.

On the other hand, in the case of styrene butadiene rubber (SSBR) obtained by solution polymerization, an organometallic catalyst such as butyl lithium having carbon anion is generally used as an initiator, and molecular weight and molecular weight distribution Of course, not only the polymer microstructure but also the macro-structure can be freely controlled, so that rubber materials can be designed to improve braking performance and reduce fuel consumption when used in tire treads. In order to improve performance, inorganic particles having a polar group that chemically interacts with the surface of particles such as silica are increasingly used instead of carbon black, and a functional group capable of bonding or interacting with such inorganic particles is added to the end of the polymer It is known that the use of the introduced modified conjugated diene polymer can further improve the tire performance.

However, in the case of the styrene-butadiene rubber obtained through solution polymerization, when it is mixed with a filler such as inorganic particles or metal oxide particles in general, the compatibility is poor and the dispersibility of the filler particles is lowered, When applied to tire material after vulcanization, the tire performance is degraded.

U.S. Patent No. 7,279,531 discloses a method of introducing a tin (Sn) -based compound as a modifying compound into a conjugated diene-based polymer to improve the dispersibility and affinity for carbon black. However, there is a limit to effectively improve bonding and dispersibility with an inorganic additive such as silica having a polar group on the surface.

U.S. Patent No. 7,335,706 uses hexachlorodisiloxane as a modifying compound to increase compatibility with silica. When the modified conjugated diene polymer prepared by using this compound is blended with silica, the fuel consumption can be increased compared with the conjugated diene polymer not modified by the bond with silica, but there is a limit to the production due to the strong toxicity However, the dispersion of silica is not sufficient and there is a limit to improvement in fuel efficiency when used in a tire.

In JP-A-8-337614, an alkoxysilane containing a glycidyl group is used as a modifying compound for compatibility with silica and strengthening of bonding. When the modified conjugated diene polymer in which the compound is introduced is mixed with silica, the fuel consumption can be increased compared with the unmodified conjugated diene polymer. However, by the coupling reaction between the alkoxysilane groups, The pattern viscosity of the diene polymer increases, and the functional groups capable of binding to the silica are consumed by the coupling reaction, so that the dispersion of the silica may not be sufficient.

In Korean Patent Laid-Open No. 10-2010-0078817, it has been attempted to improve the affinity with silica by using a coupling agent in which methacrylate and polyethylene glycol are combined, thereby improving the braking performance and fuel consumption of the wet road surface simultaneously, but the polyethylene glycol portion And the silanol groups on the surface of the silica are not strong enough to interfere with each other, dispersion of the silica may not be sufficient, and improvement of the running performance is limited.

U.S. Patent No. 6,365,668 introduces functional groups of carboxylic acid through post-reaction after polymerizing styrene butadiene rubber. When the modified conjugated diene polymer is blended with silica, the running performance and braking performance of the conjugated diene polymer can be improved compared to the unmodified conjugated diene polymer. However, the peroxide added for post- , The double bond of the 4-butadiene unit is decomposed, and the running performance may be deteriorated.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the problems of the above-described prior arts, and an object of the present invention is to provide a process for producing a conjugated diene polymer which comprises hydrolyzing a conjugated diene polymer under heat or an acid catalyst to convert an ester group into a carboxyl group or an anhydride By introducing functional monomers that can be used in combination with an additive such as an inorganic substance or a metal oxide particle to improve the dispersibility of these particles and to provide a modified conjugated diene polymer excellent in affinity with a polar inorganic additive.

Another object of the present invention is to provide a composition comprising the modified conjugated diene polymer of the present invention and an inorganic filler, wherein the composition of the present invention improves the dispersibility of the inorganic additive and the rubber to provide a low hysteresis Balance between the loss and the wet skid resistance, that is, the balance of the rotational resistance / braking property, and exhibits an excellent storage stability.

In order to solve the above-mentioned problems, the present invention includes a functional monomer which is hydrolyzed in at least one of the starting end and the terminal end of the polymer chain under heat or acid catalyst to convert the ester group into a carboxyl group or an anhydride And a modified conjugated diene polymer.

In a preferred embodiment of the present invention, the functional monomer is a monomer represented by the following formula (1).

[Chemical Formula 1]

Wherein R ₁ is hydrogen, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, R ₂ is an alkyl group having 4 to 20 carbon atoms or a 6 to 20 carbon atom-containing aryl group Or an alkylsilyl group having 3 to 20 carbon atoms and 1 to 10 silicon atoms or an arylsilyl group having 6 to 20 carbon atoms and having 1 to 10 silicon atoms and R ₂ is cleaved by thermal or acid catalysis to give an ester Is converted to a carboxylic acid group or anhydride.

In the above formula (1), preferred examples of R ₁ include hydrogen, methyl and ethyl, and preferred examples of R ₂ include a tertiary-butyl ester group, a trimethylsilyl ester group, a triethylsilyl ester group, A butoxyphenyl group, a trimethylsiloxyphenyl group, and a triethylsiloxyphenyl group.

The functional monomer is preferably selected from among tertiary-butyl acrylate, tertiary-butyl methacrylate, trimethylsilyl acrylate, trimethylsilyl methacrylate, triethylsilyl acrylate and triethylsilyl methacrylate One or more compounds may be used, but are not limited thereto.

It is preferable that the modified conjugated diene polymer of the present invention contains at least 1 to 100 functional monomers at the terminals thereof. In the case where the functional monomer is not introduced, the balance of low hysteresis loss and wet skid resistance and storage stability, which are the object of the present invention, are not improved, and when more than 100 functional monomers are introduced, I do not.

In the modified conjugated diene polymer of the present invention, the functional monomer may be contained in the polymer in an oligomer type block structure.

In the present invention, the conjugated diene polymer refers to a conjugated diene-based homopolymer obtained by polymerizing a dienic monomer alone or a conjugated diene-based copolymer obtained by copolymerizing two or more dienic monomers, or a conjugated diene- Of a vinyl monomer copolymerized with a vinyl monomer.

Therefore, the modified conjugated diene polymer of the present invention can be obtained by polymerizing at least one (co) polymer of a diene monomer or a copolymer of a diene monomer and a vinyl aromatic monomer in the presence of an organic metal catalyst such as organolithium and a hydrocarbon solvent , The functional monomer may be added to carry out the polymerization, and the polar additive may be further added as needed during the polymerization.

Examples of the diene monomer include, but are not limited to, at least one selected from 1,3-butadiene and isoprene.

Examples of the vinyl aromatic monomers include, but are not limited to, at least one selected from styrene and alphamethylstyrene.

The organometallic catalyst that can be used in the production of the modified conjugated diene polymer of the present invention is a form in which an alkali metal or an alkaline earth metal is combined with a hydrocarbon anion. Examples of the alkali metal or alkaline earth metal include lithium, sodium, But are not limited thereto. Preferred organometallic catalysts are organolithium catalysts, and non-limiting examples of organolithium catalysts include n-butyllithium having one anion, sec-butyllithium, tert-butyllithium, n-hexyllithium, isopropyllithium , Octyllithium, benzyllithium, phenyllithium, naphthyllithium, and derivatives thereof, and one kind or a mixture of two or more of them may be used. Organic lithium catalysts having both anions can also be used. Examples thereof include divinylbenzene lithium, dipropenylbenzene lithium, and lithium pyrollidide, Or a mixture of two or more thereof. In some cases, one or more organic lithium catalysts having one anion and an organic lithium catalyst having both anions can be used in combination.

In the polymerization of the modified conjugated diene polymer of the present invention, in addition to the organometallic catalyst, a polar additive may be additionally used to control the microstructure of the polymer, to improve the polymerization rate, or to control the reactivity, May vary depending on the purpose and type of the additive. Non-limiting examples of such polar additives include, but are not limited to, N, N, N ', N'-tetramethylethylenediamine (TMEDA), tetrahydrofuran (THF), diethyl ether, cycloalcohol ether, dipropyl ether, ethylene glycol, Ethylamine, ethylbutyl ether, crown ether, ditetrahydrofuryl propane, ethyltetrahydrofuryl ether, triethylamine, and derivatives thereof. With such a polar additive, the random structure of the polymer and the content of the vinyl group can be controlled according to the object, and the polymerization reaction rate can be improved.

Examples of the hydrocarbon solvent usable in the polymerization of the modified conjugated diene polymer of the present invention include n-hexane, n-heptane, cyclohexane, isooctane, methylcyclopentane, benzene, toluene and xylene. Two or more of them may be used in combination. In the polymerization, the monomers are added in an amount of 50% by weight or less, preferably 15 to 35% by weight in the hydrocarbon solvent. When the total content of the monomers is more than 50% by weight, the viscosity of the solution increases and it is difficult to control the molecular weight and the reaction heat, or it is difficult to homogeneously stir at the time of polymerization.

In the polymerization of the modified conjugated diene polymer of the present invention, the polymerization temperature may vary depending on the solvent, and polymerization is generally possible at 10 to 160 ° C. Depending on the polymerization temperature, the microstructure can be varied, and the polymerization temperature can be controlled according to the purpose.

In the polymerization of the modified conjugated diene polymer of the present invention, a coupling agent may be added. As the coupling agent, it is preferable to use two or more functional groups capable of reacting with the living anion. As the coupling agent, any one generally usable in the art can be used, and when the functional group of the coupling agent is two, a linear polymer having a molecular weight increased by two times is obtained. When the functional group of the coupling agent is three or more A star-polymer can be obtained. As the coupling agent, generally, tin-based, alkoxysilane-based or halosilane-based coupling agents may be used, and a coupling system including a glycidyl group may be used. Non-limiting examples of coupling agents include tin-based coupling agents such as diphenyltin dichloride, dibutyltin dichloride, dihexyltin dichloride, dioctyltin dichloride, phenyltin trichloride, butyltin trichloride, octyl And the alkoxysilane series may be selected from the group consisting of dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, diphenyldimethoxysilane, dipropyldimethoxysilane, dipropyldimethoxysilane, tetraethoxysilane, Butyltrimethoxysilane, butyltrimethoxysilane, ethyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, Ethoxy silane, tetramethoxy silane, tetraethoxy silane and the like can be used. Examples of the halosilane series include diphenyldichlorosilane, dihexyldichlorosilane, dioctyldichlorosilane, dibutyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, phenyltrichlorosilane, hexyltrichlorosilane, octyltrichlorosilane, butyltrichlorosilane Silane, methyltrichlorosilane, tetrachlorosilane, and the like can be used. Examples of the coupling agent containing a glycidyl group include 4,4'-methylenebis (N, N-diglycidylaniline), N, N-diglycidyl-4-glycidoxyaniline, N, N, N, N ', N'-tetraglycidyl-3,3'-diethyl-4,4'-diaminodiphenylmethane and the like can be used. The above coupling agents may be used alone or in combination of two or more. The coupling agent is not intended to be limited in structure, and any coupling agent may be used as long as it can react with an active end group such as a tin-based, alkoxysilane-based, halosilane-based, glycidyl-based.

In the modified conjugated diene polymer of the present invention, after the functional monomer is introduced into the conjugated diene polymer, the conversion of the ester group of the functional monomer into a carboxylic acid or anhydride through hydrolysis can be sufficiently hydrolyzed through heat, It is preferable to carry out the hydrolysis under an acid catalyst in order to induce the hydrolysis more efficiently. For this purpose, various acids such as hydrochloric acid, acetic acid, nitric acid, para-toluenesulfonic acid series and the like can be applied.

The present invention also provides a composition comprising the above-mentioned modified conjugated diene polymer of the present invention. The composition of the present invention is characterized by containing 0.1 to 200 parts by weight of an inorganic filler per 100 parts by weight of the modified conjugated diene polymer of the present invention.

As the inorganic filler contained in the composition of the present invention, carbon black, silica, etc. may be used alone or in combination of two or more. Particularly, when an inorganic filler having a large number of functional groups on the surface of inorganic particles such as silica is blended, the performance of the modified conjugated diene polymer of the present invention can be further improved. The inorganic filler preferably has a pH of 3 or more and 7 or less when dispersed in a 4% aqueous solution to efficiently induce hydrolysis of the ester group or phenyl ether group of the functional monomer. If the pH is less than 3, corrosion of the processing equipment may occur during the mixing of the inorganic filler and the conjugated diene polymer. When the pH is more than 7, the hydrolysis rate of the ester group or phenyl ether group of the functional monomer is slow .

The composition of the present invention is generally suitable for use as a material for tires, particularly for tire treads, and therefore may further comprise conventional additives usually used in tire compositions.

The modified diene polymer of the present invention is excellent in affinity with a polar inorganic additive such as silica, and a composition obtained by using the inorganic or metal oxide particles alone or in combination with two or more kinds of particles by using the same, , Particularly when applied to a tire tread, has an excellent balance of low hysteresis loss and wet skid resistance, improves fuel economy and braking performance, and exhibits an excellent storage stability.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Is not limited to the following examples.

[ Example ]

Experimental Method

1. Analysis of polymer microstructure

The microstructure of the polymerized polymer was confirmed using 400 MHz < 1 > H-NMR of Bruker.

2. Molecular weight measurement

Molecular weight measurements were made using two polystyrene 5 μm mixed-C columns from PLgel, in series, with a polystyrene reference sample (molecular weight 5000 g / mol) and polymerized polymer with THF as solvent. The detector uses a refractive index detector (RI).

3. Measurement of hydrolysis rate

The hydrolysis rate of the conjugated diene polymer was 0.2 part by weight of I-1076 as an antioxidant, and 50 phr of silica having a pH of 5 when it was dispersed in a 4% aqueous solution was introduced into the flask. The mixture was kneaded at 150 DEG C for 3 minutes using a rotor and cooled. It was dissolved in tetrahydrofuran (THF), filtered with a filter, and the solvent was removed from the filtrate, followed by measurement by ¹ H-NMR. The ester group hydrolysis was confirmed by the peak area of the hydrogen of the carboxylic acid (converted to carboxylic acid after hydrolysis) to 12.3 ppm, and the alkoxyphenyl group hydrolysis (converted to the phenol group after hydrolysis) to 7.9 ppm of the phenol group Of the hydrogen. Conversion ratios were calculated taking into consideration the ratio of the amounts of the butadiene and the functional monomers, and the relative area ratio to the peak area of the butadiene unit (4.3 to 6.1 ppm) in ¹ H-NMR.

4. Measurement of metamorphic rate

Two columns filled with silica-based gel (Zorbax PSM) were connected in series, and the solvent was measured with a refractive index detector (RI) using THF. A sample of polystyrene standards (molecular weight 5000 g / mol) was dissolved in the solvent together with the polymer and injected into the column for measurement. The denaturation rate was calculated by the following equation.

Modification ratio (%) = [1- (A2 x A3) / (A1 x A4)] x 100

A1: the total peak area of the sample (excluding the peak area of the sample based on polystyrene) and the total peak area of the sample when the area of the entire peak obtained in the styrene gel column is 100;

A2: When the area of the entire peak obtained in the styrene gel column is taken as 100, the peak area of the polystyrene standard sample,

A3: When the area of the entire peak obtained in the silica gel column is taken as 100, the sample peak area not adsorbed to the silica gel gel,

A4: Peak area of the polystyrene-based sample when the area of the entire peak obtained in the silica gel column is taken as 100.

5. Tensile test

The cured specimens were prepared as c-type dumbbells and measured using a universal testing machine (LLOYD UTM) according to the ASTM 412 tensile test method.

6. Viscoelastic properties

The tan δ, the viscoelastic property of the vulcanized specimen, was measured with a temperature sweep at 10 Hz and 0.1% strain conditions using DMTA equipment. When the value of tan? At 0 占 폚 is high, the wet skid property which is braking is excellent, and when the tan? Value at 60 占 폚 is low, low hysteresis is exhibited and the fuel efficiency is excellent.

7. Mineral Particle Dispersibility

The dispersibility of the modified conjugated diene polymer and inorganic particles was confirmed by payne effect using RPA2000 manufactured by Alpha Technology Inc. as a sample before vulcanization after blending with Hakke. The Pheny effect is shown by the difference of 0.2% and 40% at 0.1Hz and 60 ℃, and the smaller the value, the better the dispersibility of inorganic particles.

8. Pattern viscosity

The pattern viscosity of the modified conjugated diene polymer itself was measured on the basis of ML (1 + 4) at 100 ° C using a Mooney viscometer manufactured by Alpha technology.

9. Storage stability (cold flow)

The storage stability analysis was carried out at a temperature of 50 DEG C through a 1/4 inch orifice for one minute at a pressure of 3.5 psi. The lengths of the specimens were compared by increasing the length of the specimen after one day, by placing a piece of polymer 3 cm / 3 cm / 3 cm in height on a glass plate inclined at an angle of 30 ° from room temperature.

Example  One

34 g of styrene, 126 g of 1,3-butadiene and 830 g of hexane were placed in a 2 L autoclave reactor, 0.9 ml of tetramethylethylenediamine (TMEDA) was added thereto, and the temperature of the reactor was raised to 40 캜 while rotating with a stirrer under a nitrogen atmosphere. When the reactor temperature reached the set temperature, 5.6 mL of 0.3M butyl lithium (n-BuLi) was added to conduct the polymerization reaction. After 10 minutes from the reaction temperature reaching the maximum temperature, 80 mmol of t-butyl methacrylate was added to carry out further polymerization. Trimethylolpropane triglycidyl ether was added for coupling, After an additional 10 minutes, ethanol was added to terminate the polymerization. After the polymer solution was discharged from the reactor, the antioxidant Irganox-1076 was added in an amount of 0.2 parts by weight based on 100 parts by weight of the polymer. In order to remove hexane as a solvent of the polymer, the produced polymer was placed in heated hot water and stirred to remove the solvent, followed by roll drying to remove the residual solvent.

Example  2

except that t-butyl acrylate was used in place of t-butyl methacrylate.

Example  3

The procedure of Example 1 was repeated except that trimethylsilyl methacrylate was used instead of t-butyl methacrylate.

Comparative Example  One

except that t-butyl methacrylate was not used.

Comparative Example  2

The procedure of Example 1 was repeated, except that methyl methacrylate was used instead of t-butyl methacrylate.

Experimental Example : Polymer and Mineral Kneading  And physical property measurement experiment

Each of the polymers obtained in the above Examples and Comparative Examples was blended in the composition shown in Table 1 below to prepare a composition. A method of kneading the polymer composition was a Haake Polylab OS Rheodrive manufactured by Thermo Scientific Inc., and a bombarded rotor was used.

The formulation proceeded in two steps. The kneading was carried out in the same manner as in the first kneading, except that the first kneading was performed at a rate of 75% by weight and the rotor was rotated at 60 rpm to prepare a polymer, filler (silica), oil, zinc oxide (ZnO), stearic acid, silane coupling agent -PPD to control the temperature to obtain a first composition at 160 캜. In the second kneading, the compound obtained in the first kneading is cooled to room temperature, and sulfur and diphenyl guanidine (DPG: Diphenyl Guanidine), N-cyclohexyl-2-benzothiazole sulfonamide (CBS: N-cyclohexyl-2-benzothiazole sulfonamide) was added and kneaded for 5 minutes. The compounded composition was vulcanized at 170 캜 in a T90 + 5 min press to prepare a vulcanized rubber specimen.

[Table 1]

The physical properties and performance of the polymer and polymer composition prepared according to the present invention were evaluated and shown in the following [Table 2] and [Table 3], respectively.

[Table 2]

* Styrene content and vinyl content are calculated by H-NMR.

* The vinyl content is the ratio of the vinyl groups produced by the 1,2-bond among the total butadiene monomers.

[Table 3]

As shown in Tables 2 and 3, in Examples 1 to 3 according to the present invention, the ester groups of the functional monomers introduced into the polymer were converted into carboxylic acid groups by hydrolysis, so that the hydrolysis rate, , The tensile strength and the modulus of 300% were high, and the dispersibility when mixed with the filler was excellent. When used as a tire tread, it had a high tan δ at 0 ° C and was excellent in braking performance on a wet road surface. Of the total amount of the diene-based rubber material.

On the other hand, Comparative Example 1 had a low silica dispersibility when the functional monomer of the present invention was not used. As a result, the tensile strength and the 300% modulus were much lower than those of Examples 1 to 3, The use of a methacrylate-based monomer similar to the functional monomer of the present invention, which is a methyl ester group which is not easily hydrolyzed, does not improve the polarity as in the case of introducing the functional monomer of the present invention, The properties such as acidity, tensile strength and 300% modulus were inferior to those of Examples 1 to 3, but the methyl methacrylate monomer was superior to Comparative Example 1 because of its higher polarity than SBR. Examples 1 to 3 and Comparative Example 2 were found to have improved cold flow as compared with Comparative Example 1.

Claims (10)

A modified conjugated diene polymer comprising a functional monomer represented by the following formula (1) at the end of a polymer chain:
[Chemical Formula 1]

(Wherein R ₁ is hydrogen, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, R ₂ is an alkyl group having 4 to 20 carbon atoms and a tertiary carbon atom, or an aryl group having 6 to 20 carbon atoms Or an alkylsilyl group having 3 to 20 carbon atoms and 1 to 10 silicon atoms or an arylsilyl group having 6 to 20 carbon atoms and 1 to 10 silicon atoms and having R ₂ separated by thermal or acid catalysis, Wherein the ester group is converted to a carboxylic acid group or anhydride and the polymer is bonded to the C = C portion of the functional monomer introduced at the terminal thereof, wherein the functional monomer is selected from the group consisting of tertiary-butyl acrylate, tertiary-butyl methacrylate Is at least one compound selected from the group consisting of trimethylsilyl acrylate, trimethylsilyl methacrylate, triethylsilyl acrylate and triethylsilyl methacrylate. delete The modified conjugated diene-based polymer according to claim 1, wherein 1 to 100 functional monomers are contained in the polymer. The modified conjugated diene-based polymer according to claim 1, wherein the functional monomer is contained in the polymer in an oligomer-type block structure. The polymer of claim 1, wherein the polymer is prepared by (co) polymerizing one or more diene monomers, or by copolymerizing a dienic monomer and a vinyl aromatic monomer and then polymerizing the functional monomer Wherein the modified conjugated diene polymer is a conjugated diene polymer. The conjugated diene according to claim 5, wherein the diene monomer is at least one selected from 1,3-butadiene and isoprene, and the vinyl aromatic monomer is at least one selected from styrene and alphamethylstyrene. Based polymer. A composition comprising 0.1 to 200 parts by weight of an inorganic filler based on 100 parts by weight of the modified conjugated diene polymer of any one of claims 1 to 6. The composition according to claim 7, wherein the inorganic filler is a carbon black-based filler, a silica-based filler, or a mixture thereof. The composition according to claim 7, wherein the inorganic filler has a pH of 3 or more and 7 or less when dispersed in a 4% aqueous solution. 8. The composition of claim 7, wherein the composition is a composition for tire material.