KR102744316B1 - Modified conjugated diene polymer, preparation method thereof and rubber composition comprising the same - Google Patents

Abstract

The present invention relates to a highly branched, high molecular weight, modified conjugated diene polymer having excellent wear resistance, a method for producing the same, and a rubber composition comprising the same. The present invention provides a modified conjugated diene polymer including a repeating unit derived from a conjugated diene monomer and a functional group derived from a modifier represented by the chemical formula 1, a method for producing the same, and a rubber composition comprising the same.

Description

Modified conjugated diene polymer, preparation method thereof, and rubber composition comprising the same {MODIFIED CONJUGATED DIENE POLYMER, PREPARATION METHOD THEREOF AND RUBBER COMPOSITION COMPRISING THE SAME}

The present invention relates to a high molecular weight modified conjugated diene polymer having excellent wet road resistance and rolling resistance and improved wear resistance, a method for producing the same, and a rubber composition comprising the same.

Recently, in response to the demand for fuel efficiency in automobiles, conjugated diene polymers that have low rolling resistance, excellent wear resistance and tensile properties, and also have steering stability represented by wet road resistance are required as rubber materials for tires.

In order to reduce the rolling resistance of tires, there is a method of reducing the hysteresis loss of vulcanized rubber, and as evaluation indices of such vulcanized rubber, rebound elasticity, tan δ, Goodrich heat generation, etc. at 50℃ to 80℃ are used. In other words, a rubber material having a large rebound elasticity or a small tan δ and Goodrich heat generation at the above temperature is desirable.

Natural rubber, polyisoprene rubber, or polybutadiene rubber are known as rubber materials with small hysteresis loss, but they have the problem of low wet road resistance. Therefore, conjugated diene polymers or copolymers such as styrene-butadiene rubber (hereinafter referred to as SBR) or butadiene rubber (hereinafter referred to as BR) have been manufactured by emulsion polymerization or solution polymerization and used as rubber for tires. Among these, the greatest advantage of solution polymerization over emulsion polymerization is that the vinyl structure content and styrene content, which determine the rubber properties, can be arbitrarily controlled, and the molecular weight and properties can be controlled by coupling or modification. Therefore, the structure of the finally manufactured SBR or BR is easy to change, and the movement of the chain ends can be reduced by bonding or modification of the chain ends, and the bonding strength with fillers such as silica or carbon black can be increased, so SBR manufactured by solution polymerization is widely used as a rubber material for tires.

When such solution-polymerized SBR is used as a rubber material for tires, the glass transition temperature of the rubber can be raised by increasing the vinyl content in the SBR, thereby controlling the tire's required physical properties such as driving resistance and braking power, and fuel consumption can be reduced by appropriately controlling the glass transition temperature. The solution-polymerized SBR is manufactured using an anionic polymerization initiator, and the chain terminals of the formed polymer are bonded or modified using various modifiers and used. For example, U.S. Patent No. 4,397,994 proposes a technology for bonding the active anion of the chain terminal of a polymer obtained by polymerizing styrene-butadiene in a nonpolar solvent using a monofunctional initiator, alkyllithium, using a bonding agent such as a tin compound.

Meanwhile, the polymerization of the SBR or BR can be carried out by batch or continuous polymerization. In the case of batch polymerization, the molecular weight distribution of the manufactured polymer is narrow, so there is an advantage in terms of improving physical properties, but there are problems such as low productivity and poor processability. In the case of continuous polymerization, the polymerization is carried out continuously, so there is an advantage in terms of excellent productivity and improving processability, but there is a problem such as poor physical properties due to a broad molecular weight distribution. Accordingly, there is a continuous demand for research to simultaneously improve productivity, processability, and physical properties when manufacturing SBR or BR.

US 4397994 A

The present invention has been made to solve the problems of the above-mentioned prior art, and aims to provide a modified conjugated diene polymer which is manufactured by reacting an active polymer with a modifier represented by Chemical Formula 1, has a high molecular weight with a highly branched structure, thereby exhibiting excellent wear resistance, and includes a functional group derived from the modifier, thereby exhibiting excellent filler affinity and compounding processability.

In addition, the present invention aims to provide a method for producing the above-mentioned modified conjugated diene polymer.

In addition, the present invention aims to provide a rubber composition comprising the modified conjugated diene polymer and a filler.

According to one embodiment of the present invention for solving the above problem, the present invention provides a modified conjugated diene polymer including a repeating unit derived from a conjugated diene monomer and a functional group derived from a modifier represented by the following chemical formula 1:

[Chemical Formula 1]

In the above chemical formula 1,

R ₁ to R ₈ are independently an alkylene group having 1 to 20 carbon atoms or an alkenylene group having 2 to 20 carbon atoms, which is unsubstituted or substituted with a substituent, wherein the substituent is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,

A ₁ to A ₄ are substituents independently represented by the following chemical formula a,

[chemical formula a]

In the above chemical formula a,

R ₉ to R ₁₁ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, wherein at least one of R ₉ to R ₁₁ is an alkoxy group having 1 to 20 carbon atoms.

In addition, the present invention provides a method for producing the modified conjugated diene polymer, including the step (S1) of producing an active polymer by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of a polymerization initiator in a hydrocarbon solvent; and the step (S2) of reacting the active polymer with a modifier represented by the chemical formula 1.

In addition, the present invention provides a rubber composition comprising the modified conjugated diene polymer and a filler.

The modified conjugated diene polymer according to the present invention is prepared by reacting an active polymer with a modifier represented by Chemical Formula 1, and can have a highly branched structure and a high molecular weight, thereby significantly improving wear resistance. In addition, by including a functional group derived from the modifier, the polymer can have excellent affinity with a filler, and thus excellent compounding processability.

In addition, the method for producing a modified conjugated diene polymer according to the present invention includes a step of reacting an active polymer with a modifier represented by Chemical Formula 1, thereby easily producing a modified conjugated diene polymer having a highly branched structure, high molecular weight, and excellent wear resistance.

In addition, the rubber composition according to the present invention has excellent wear resistance by including the above-described modified conjugated diene polymer, and at the same time, excellent compounding processability, so that it has excellent compounding properties such as tensile properties, wet road resistance, and rolling resistance.

Hereinafter, the present invention will be described in more detail to help understand the present invention.

The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner.

In the present invention, the term 'substitution' may mean that a hydrogen of a functional group, an atomic group, or a compound is substituted with a specific substituent, and when a hydrogen of a functional group, an atomic group, or a compound is substituted with a specific substituent, one or two or more substituents may be present depending on the number of hydrogens present in the functional group, an atomic group, or a compound, and when multiple substituents are present, each of the substituents may be the same as or different from each other.

In the present invention, the term 'alkyl group' may mean a monovalent aliphatic saturated hydrocarbon, and may mean all of linear alkyl groups such as methyl, ethyl, propyl, and butyl; branched alkyl groups such as isopropyl, sec-butyl, tert-butyl, and neopentyl; and cyclic saturated hydrocarbons, or cyclic unsaturated hydrocarbons including one or more unsaturated bonds.

In the present invention, the term 'alkylene group' may mean a divalent aliphatic saturated hydrocarbon such as methylene, ethylene, propylene, and butylene.

In the present invention, the term 'cycloalkyl group' may mean a cyclic saturated hydrocarbon.

In the present invention, the term 'aryl group' may mean a cyclic aromatic hydrocarbon, and may also mean a monocyclic aromatic hydrocarbon in which one ring is formed, or a polycyclic aromatic hydrocarbon in which two or more rings are combined.

In the present invention, the terms 'derived repeating unit' and 'derived functional group' may mean a component, structure, or the substance itself derived from a certain substance.

The present invention provides a modified conjugated diene polymer having a highly branched structure and high molecular weight and excellent wear resistance.

A modified conjugated diene polymer according to one embodiment of the present invention is characterized by including a repeating unit derived from a conjugated diene monomer and a functional group derived from a modifier represented by the following chemical formula 1.

[Chemical Formula 1]

In the above chemical formula 1,

R ₁ to R ₈ are independently an alkylene group having 1 to 20 carbon atoms or an alkenylene group having 2 to 20 carbon atoms, which is unsubstituted or substituted with a substituent, wherein the substituent is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,

A ₁ to A ₄ are substituents independently represented by the following chemical formula a,

[chemical formula a]

In the above chemical formula a,

R ₉ to R ₁₁ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, wherein at least one of R ₉ to R ₁₁ is an alkoxy group having 1 to 20 carbon atoms.

According to one embodiment of the present invention, the modified conjugated diene polymer may include a repeating unit derived from a conjugated diene monomer and a functional group derived from a modifier represented by Chemical Formula 1, wherein the repeating unit derived from the conjugated diene monomer may refer to a repeating unit formed when the conjugated diene monomer is polymerized, and the functional group derived from the modifier represented by Chemical Formula 1 may be a functional group derived from the modifier represented by Chemical Formula 1 present in a polymer chain including the repeating unit derived from the conjugated diene monomer, and the functional group derived from the modifier represented by Chemical Formula 1 may be present at at least one terminal of the polymer chain.

In addition, according to another embodiment of the present invention, the modified conjugated diene polymer may further include a repeating unit derived from an aromatic vinyl monomer, and in this case, the modified conjugated diene polymer may be a copolymer including a repeating unit derived from a conjugated diene monomer, a repeating unit derived from an aromatic vinyl monomer, and a functional group derived from a modifier represented by Chemical Formula 1. Here, the repeating unit derived from an aromatic vinyl monomer may mean a repeating unit formed when the aromatic vinyl monomer is polymerized.

According to one embodiment of the present invention, the conjugated diene monomer may be at least one selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halo-1,3-butadiene (halo means a halogen atom).

The above aromatic vinyl monomer may be at least one selected from the group consisting of, for example, styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, 1-vinyl-5-hexylnaphthalene, 3-(2-pyrrolidino ethyl)styrene, 4-(2-pyrrolidino ethyl)styrene, and 3-(2-pyrrolidino-1-methyl ethyl)-α-methylstyrene.

As another example, the modified conjugated diene polymer may be a copolymer further including a repeating unit derived from a diene monomer having 1 to 10 carbon atoms together with the repeating unit derived from the conjugated diene monomer. The repeating unit derived from the diene monomer may be a repeating unit derived from a diene monomer different from the conjugated diene monomer, and the diene monomer different from the conjugated diene monomer may be, for example, 1,2-butadiene. When the modified conjugated diene polymer is a copolymer further including a diene monomer, the modified conjugated diene polymer may include a repeating unit derived from the diene monomer in an amount of from more than 0 wt% to 1 wt%, from more than 0 wt% to 0.1 wt%, from more than 0 wt% to 0.01 wt%, or from more than 0 wt% to 0.001 wt%, and has an effect of preventing gel formation within this range.

According to one embodiment of the present invention, when the modified conjugated diene polymer is a copolymer, the copolymer may be a random copolymer, and in this case, there is an excellent effect of balance between each physical property. The random copolymer may mean that the repeating units forming the copolymer are arranged randomly.

According to one embodiment of the present invention, the modified conjugated diene polymer is manufactured by a manufacturing method including a step of reacting an active polymer described below with a modifier represented by Chemical Formula 1, wherein the modifier represented by Chemical Formula 1 has a plurality of reaction active sites capable of reacting with the active polymer, so that a plurality of polymer chains composed of a conjugated diene monomer-derived repeating unit of the active polymer or a conjugated diene monomer-derived repeating unit and an aromatic vinyl monomer-derived repeating unit are coupled to the modifier to each other, thereby allowing the polymer to have a highly branched structure and a high molecular weight, and thus allowing the polymer to have significantly excellent wear resistance.

In the chemical formula 1 above, R ₁ to R ₈ are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, A ₁ to A ₄ are each independently a substituent represented by the following chemical formula a, and in the chemical formula a above, R ₉ to R ₁₁ are each independently an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, wherein at least one of R ₉ to R ₁₁ may be an alkoxy group having 1 to 10 carbon atoms.

Additionally, as another example, the modifier represented by the chemical formula 1 may contain 8 to 12 alkoxy groups in the molecule.

Specifically, the modifier represented by the chemical formula 1 may be at least one selected from compounds represented by the following chemical formulas 1-1 to 1-6.

[Chemical Formula 1-1]

[Chemical Formula 1-2]

[Chemical Formula 1-3]

[Chemical Formula 1-4]

[Chemical Formula 1-5]

[Chemical Formula 1-6]

In the above chemical formulas 1-1 to 1-6, Me is a methyl group and Et is an ethyl group.

In addition, the modified conjugated diene polymer according to one embodiment of the present invention may have a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 800,000 g/mol to 3,000,000 g/mol, 1,000,000 g/mol to 3,000,000 g/mol, or 1,200,000 to 3,000,000 g/mol, and within this range, the wear resistance of the modified conjugated diene polymer may be excellent.

Meanwhile, the modified conjugated diene polymer may have a number average molecular weight (Mn) of 500,000 g/mol to 2,000,000 g/mol, 800,000 g/mol to 2,000,000 g/mol, or 800,000 g/mol to 1,700,000 g/mol, and may have a number average molecular weight and a weight average molecular weight in the above-mentioned range while having a molecular weight distribution (PDI; MWD; Mw/Mn) of 1.0 or more and 5.0 or less, or 1.0 or more and 3.0 or less, in which case there is an excellent effect of balance between each physical property.

In addition, the modified conjugated diene polymer may have a Mooney stress relaxation rate of 0.050 to 0.300 measured at 140°C, and specifically, the Mooney stress relaxation rate may be 0.050 to 0.200 or 0.050 to 0.150. Here, the Mooney stress relaxation rate may be an indicator of the degree of branching and the molecular weight of the polymer, and for example, when the Mooney stress relaxation rate decreases, the degree of branching and the molecular weight of the polymer tend to increase.

Meanwhile, Mooney stress relaxation rate is generally thought to be related to Mooney viscosity, but the higher the degree of branching of the modified conjugated diene polymer, the smaller the Mooney stress relaxation rate. Therefore, even if the Mooney viscosity is equivalent, the Mooney stress relaxation rate may differ depending on the degree of branching.

As another example, the modified conjugated diene polymer may have a Mooney viscosity at 140°C of 80 or more, 80 to 150, or 80 to 140.

When the weight average molecular weight is within the above-mentioned range and the Mooney stress relaxation rate is within the above-mentioned range, the balance between properties is excellent and the wear resistance can be greatly improved.

Here, the Mooney viscosity may be measured by using a Large Rotor of Monsanto MV2000E under the conditions of 140°C and a Rotor Speed of 2±0.02 rpm, after leaving the polymer at room temperature (23±5°C) for more than 30 minutes, sampling 27±3 g and filling it inside the die cavity, and operating the platen to apply torque. In addition, the Mooney stress relaxation ratio was measured by measuring the slope value of the Mooney viscosity change that appears when the torque is released after measuring the Mooney viscosity, and its absolute value was defined as the Mooney stress relaxation ratio.

In addition, the modified conjugated diene polymer may have a vinyl content of 5 wt% or more, 10 wt% or more, or from 10 wt% to 80 wt%. Here, the vinyl content may mean the content of a 1,2-added, but not a 1,4-added, conjugated diene monomer with respect to 100 wt% of the conjugated diene copolymer composed of a monomer having a vinyl group and an aromatic vinyl monomer.

In addition, the present invention provides a method for producing the modified conjugated diene polymer.

The method for producing the modified conjugated diene polymer according to one embodiment of the present invention is characterized by including a step (S1) of producing an active polymer by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of a polymerization initiator in a hydrocarbon solvent; and a step (S2) of reacting the active polymer with a modifying agent represented by the following chemical formula 1.

[Chemical Formula 1]

In the chemical formula 1 above, R ₁ to R ₈ and A ₁ to A ₄ are as described above, and the conjugated diene monomer and the aromatic vinyl monomer are also as described above.

The hydrocarbon solvent is not particularly limited, but may be at least one selected from the group consisting of n-pentane, n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene, and xylene.

In addition, according to one embodiment of the present invention, the polymerization initiator may be an organometallic compound, and the organometallic compound is not particularly limited, but may be, for example, selected from the group consisting of methyllithium, isopropyllithium, propyllithium, isopropyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyllithium, n-eicosyllithium, 4-butylphenyllithium, 4-tolyllithium, cyclohexyllithium, 3,5-di-n-heptylcyclohexyllithium, 4-cyclopentyllithium, naphthylsodium, naphthylpotassium, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithium sulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodium amide, potassium amide, and lithium isopropylamide. There may be more than one type.

According to one embodiment of the present invention, the polymerization initiator may be used in an amount of 0.01 mmol to 10 mmol, 0.05 mmol to 5 mmol, 0.1 mmol to 2 mmol, 0.1 mmol to 1 mmol, or 0.15 to 0.8 mmol based on 100 g of the total monomer. Here, the monomer may represent the content of the conjugated diene monomer or the total amount of the conjugated diene monomer and the aromatic vinyl monomer.

The polymerization in the step (S1) may be, for example, anionic polymerization, and as a specific example, may be a living anionic polymerization having an anion active site at the polymerization terminal by a growth polymerization reaction by anion. In addition, the polymerization in the step (S1) may be temperature-elevated polymerization, isothermal polymerization, or isothermal polymerization (adiabatic polymerization), and the isothermal polymerization may mean a polymerization method including a step of polymerizing by its own reaction heat without arbitrarily applying heat after introducing a denaturing initiator, the temperature-elevated polymerization may mean a polymerization method of increasing the temperature by arbitrarily applying heat after introducing the denaturing initiator, and the isothermal polymerization may mean a polymerization method of maintaining the temperature of the polymerization product constant by applying heat to increase the heat or removing heat after introducing the denaturing initiator.

In addition, the polymerization in the above step (S1) can be performed through a batch reaction, a continuous reaction, or an appropriate combination thereof.

In addition, according to one embodiment of the present invention, the polymerization in step (S1) may be carried out by further including a diene compound having 1 to 10 carbon atoms in addition to the conjugated diene monomer, and in this case, there is an effect of preventing a gel from being formed on the wall of the reactor during long-term operation. An example of the diene compound may be 1,2-butadiene.

The polymerization in the above step (S1) can be carried out at a temperature range of, for example, 80°C or less, -20°C to 80°C, 0°C to 80°C, 0°C to 70°C, or 10°C to 70°C, and has the effect of increasing the polymerization conversion rate of the polymerization reaction within this range.

The active polymer manufactured by the above step (S1) may mean a polymer in which a polymer anion and an organic metal cation are combined.

In addition, the polymerization of the step (S1) may be carried out including a polar additive, and the polar additive may be added in a proportion of 0.001 g to 50 g, 0.001 g to 10 g, or 0.005 g to 0.1 g based on 100 g of the total monomer. In another example, the polar additive may be added in a proportion of 0.001 g to 10 g, 0.005 g to 5 g, or 0.005 g to 4 g based on 1 mmol of the total polymerization initiator.

The polar additive may be, for example, at least one selected from the group consisting of tetrahydrofuran, 2,2-di(2-tetrahydrofuryl)propane, diethyl ether, cycloamyl ether, dipropyl ether, ethylene methyl ether, ethylene dimethyl ether, diethylene glycol, dimethyl ether, tert-butoxyethoxyethane, bis(3-dimethylaminoethyl)ether, (dimethylaminoethyl)ethyl ether, trimethylamine, triethylamine, tripropylamine, N,N,N',N'-tetramethylethylenediamine, sodium mentholate, and 2-ethyl tetrahydrofurfuryl ether, and preferably 2,2-di(2-tetrahydrofuryl)propane, triethylamine, tetramethylethylenediamine, sodium mentholate, or 2-ethyl tetrahydrofurfuryl. It may be ether (2-ethyl tetrahydrofurfuryl ether), and when the polar additive is included, there is an effect of inducing easy formation of a random copolymer by compensating for the difference in reaction speed between a conjugated diene monomer, or a conjugated diene monomer and an aromatic vinyl monomer when copolymerizing them.

According to one embodiment of the present invention, the reaction of the step (S2) may be a modification reaction or coupling reaction using a modification agent, and at this time, the modification agent may be used in an amount of 0.01 mmol to 10 mmol based on 100 g of the total monomer. In another example, the modification agent may be used in an amount of 0.1 mol to 10 mol, 0.1 mol to 5 mol, or 0.1 mol to 3 mol based on 1 mol of the polymerization initiator of the step (S1).

In addition, the present invention provides a rubber composition comprising the above-mentioned modified conjugated diene polymer.

The above rubber composition may contain the modified conjugated diene polymer in an amount of 10 wt% or more, 10 wt% to 100 wt%, or 20 wt% to 90 wt%, and within this range, the composition has excellent mechanical properties such as tensile strength and wear resistance, and excellent balance between each property.

In addition, the rubber composition may further include other rubber components as needed in addition to the modified conjugated diene polymer, and at this time, the rubber component may be included in an amount of 90 wt% or less based on the total weight of the rubber composition. As a specific example, the other rubber component may be included in an amount of 1 to 900 wt% based on 100 wt% of the modified conjugated diene polymer.

The above rubber component may be, for example, natural rubber or synthetic rubber, and specific examples thereof include natural rubber (NR) including cis-1,4-polyisoprene; modified natural rubber such as epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and hydrogenated natural rubber, which are modified or refined from the above general natural rubber; It can be a synthetic rubber such as styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), butyl rubber (IIR), ethylene-propylene copolymer, polyisobutylene-co-isoprene, neoprene, poly(ethylene-co-propylene), poly(styrene-co-butadiene), poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene), poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene), polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, halogenated butyl rubber, and any one of these or a mixture of two or more thereof can be used.

The above rubber composition may contain, for example, 0.1 to 200 parts by weight, or 10 to 120 parts by weight, of a filler based on 100 parts by weight of the modified conjugated diene polymer of the present invention. The filler may be, for example, a silica-based filler, and specific examples thereof may include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, or colloidal silica, and preferably wet silica, which has the most excellent effect of improving fracture characteristics and achieving wet grip properties. In addition, the rubber composition may further contain a carbon black-based filler, if necessary.

As another example, when silica is used as the filler, a silane coupling agent may be used together to improve reinforcing properties and low heat generation, and specific examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-Triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-Triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-Trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-Triethoxysilylpropylbenzolyltetrasulfide, 3-Triethoxysilylpropylmethacrylate monosulfide, 3-Trimethoxysilylpropylmethacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, or dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, and the like, and any one or a mixture of two or more of these may be used. Preferably, considering the effect of improving reinforcing properties, it may be bis(3-triethoxysilylpropyl)polysulfide or 3-trimethoxysilylpropylbenzothiazyl tetrasulfide.

In addition, since the rubber composition according to one embodiment of the present invention uses a modified conjugated diene polymer having a functional group having high affinity for silica introduced into an active site as a rubber component, the amount of the silane coupling agent can be reduced compared to the usual case, and accordingly, the silane coupling agent can be used in an amount of 1 to 20 parts by weight, or 5 to 15 parts by weight, based on 100 parts by weight of silica, and within this range, the effect as a coupling agent is sufficiently exhibited while also having the effect of preventing gelation of the rubber component.

The rubber composition according to one embodiment of the present invention may be sulfur crosslinkable and may further include a vulcanizing agent. The vulcanizing agent may be specifically sulfur powder and may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the rubber component, and within this range, the vulcanized rubber composition has the effect of securing the necessary elastic modulus and strength while exhibiting excellent fuel efficiency.

The rubber composition according to one embodiment of the present invention may further include, in addition to the above-described components, various additives commonly used in the rubber industry, specifically, a vulcanization accelerator, a process oil, an antioxidant, a plasticizer, an anti-aging agent, a scorch inhibitor, zinc white, stearic acid, a thermosetting resin, or a thermoplastic resin.

The above-mentioned vulcanization accelerator may be, for example, a thiazole-based compound such as M(2-mercaptobenzothiazole), DM(dibenzothiazyl disulfide), CZ(N-cyclohexyl-2-benzothiazyl sulfenamide), or a guanidine-based compound such as DPG (diphenyl guanidine), and may be included in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the rubber component.

The above process oil acts as a softener in the rubber composition, and may be, for example, a paraffinic, naphthenic, or aromatic compound. When considering tensile strength and wear resistance, an aromatic process oil may be used, and when considering hysteresis loss and low-temperature characteristics, a naphthenic or paraffinic process oil may be used. The above process oil may be included in an amount of, for example, 100 parts by weight or less with respect to 100 parts by weight of the rubber component, and within this range, there is an effect of preventing a decrease in the tensile strength and low heat generation (low fuel consumption) of the vulcanized rubber.

The antioxidant may be, for example, 2,6-di-t-butylparacresol, dibutylhydroxytoluenyl, 2,6-bis((dodecylthio)methyl)-4-nonylphenol or 2-methyl-4,6-bis((octylthio)methyl)phenol, and may be used in an amount of 0.1 to 6 parts by weight per 100 parts by weight of the rubber component.

The above-mentioned anti-aging agent may be, for example, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, or a high-temperature condensate of diphenylamine and acetone, and may be used in an amount of 0.1 to 6 parts by weight per 100 parts by weight of the rubber component.

The rubber composition according to one embodiment of the present invention can be obtained by mixing using a mixer such as a Banbury mixer, a roll mixer, or an internal mixer according to the above compounding prescription, and a rubber composition having low heat generation and excellent wear resistance can be obtained by a vulcanization process after molding processing.

Accordingly, the rubber composition can be useful in the manufacture of various components of a tire, such as a tire tread, undertread, sidewall, carcass coating rubber, belt coating rubber, bead filler, squeegee, or bead coating rubber, or various industrial rubber products, such as an anti-vibration rubber, belt conveyor, and hose.

In addition, the present invention provides a tire manufactured using the rubber composition.

The above tire may include a tire or tire tread.

Hereinafter, the present invention will be described in detail by way of examples in order to specifically explain the present invention. However, the examples according to the present invention may be modified in various different forms, and the scope of the present invention should not be construed as being limited to the examples described below. The examples of the present invention are provided in order to more completely explain the present invention to a person having average knowledge in the art.

In addition, the materials used in the examples and comparative examples below were manufactured and used by referring to commonly known manufacturing methods, except where specifically mentioned, or were purchased and used as distributed materials.

Manufacturing example 1

A 5 L round bottom flask equipped with a shrink line was decompressed to completely remove moisture, and 1000 ml of acetonitrile was added under an air atmosphere, followed by adding 4 mol (963.2 g) of (3-chloropropyl)triethoxysilane and 10.12 g of triethylamine, and cooled to 0°C. Thereafter, 1 mol (172.27 g) of 1,4,7,10-tetraazacyclododecane was added using a dropping funnel over 1 hour, and after the addition was completed, the temperature was increased to 40°C and stirred for 4 hours to proceed with the reaction. Thereafter, the solvent and triethylamine were removed using a rotary condenser to prepare a compound represented by the following chemical formula 1-1.

[Chemical Formula 1-1]

Manufacturing example 2

A compound represented by the following chemical formula 1-2 was prepared in the same manner as in Manufacturing Example 1, except that 4 mol (794.9 g) of (3-chloropropyl)trimethoxysilane was used instead of (3-chloropropyl)triethoxysilane in Manufacturing Example 1.

[Chemical Formula 1-2]

Manufacturing example 3

A compound represented by the following chemical formula 1-3 was prepared in the same manner as in Manufacturing Example 1, except that 4 mol (839.2 g) of (3-chloropropyl)diethoxymethylsilane was used instead of (3-chloropropyl)triethoxysilane in Manufacturing Example 1.

[Chemical Formula 1-3]

Manufacturing example 4

A compound represented by the following chemical formula 1-4 was prepared in the same manner as in Preparation Example 1, except that 1 mol (200.32 g) of 1,4,8,11-tetraazacyclotetradecane was used instead of 1,4,7,10-tetraazacyclododecane in Preparation Example 1.

[Chemical Formula 1-4]

Manufacturing example 5

A compound represented by the following chemical formula 1-5 was prepared in the same manner as in Manufacturing Example 4, except that 4 mol (794.9 g) of (3-chloropropyl)trimethoxysilane was used instead of (3-chloropropyl)triethoxysilane in Manufacturing Example 4.

[Chemical Formula 1-5]

Manufacturing example 6

A compound represented by the following chemical formula 1-6 was prepared in the same manner as in Manufacturing Example 4, except that 4 mol (839.2 g) of (3-chloropropyl)diethoxymethylsilane was used instead of (3-chloropropyl)triethoxysilane in Manufacturing Example 4.

[Chemical Formula 1-6]

Example 1

A 20 L autoclave reactor was charged with 100 g of styrene, 880 g of 1,3-butadiene, 5,000 g of n-hexane, and 0.70 g of 2,2-di(2-tetrahydrofuryl)propane as a polar additive, and the internal temperature of the reactor was increased to 50°C. When the internal temperature of the reactor reached 50°C, 3.0 mmol of n-butyllithium was added as a polymerization initiator, and an adiabatic temperature-raising reaction was performed. After about 20 minutes, 20 g of 1,3-butadiene was added, and the ends of the polymer chains were capped with butadiene. After 5 minutes, 1.2 mmol of the compound represented by Chemical Formula 1-1 prepared in Manufacturing Example 1 as a modifier was added, and the reaction was performed for 15 minutes. Afterwards, the polymerization reaction was stopped using ethanol, and 45 ml of a solution containing 0.3 wt% IR1520 (BASF), an antioxidant, dissolved in n-hexane, was added. The resulting polymer was placed in hot water heated by steam and stirred to remove the solvent, thereby producing a modified conjugated diene polymer.

Example 2

In Example 1, a modified conjugated diene polymer was manufactured in the same manner as in Example 1, except that 1.2 mmol of the compound represented by the chemical formula 1-2 manufactured in Preparation Example 2 was added instead of the compound represented by the chemical formula 1-1 to carry out the modification reaction.

Example 3

In Example 1, a modified conjugated diene polymer was manufactured in the same manner as in Example 1, except that 1.2 mmol of the compound represented by the chemical formula 1-3 manufactured in Preparation Example 3 was added instead of the compound represented by the chemical formula 1-1 to carry out the modification reaction.

Example 4

In Example 1, a modified conjugated diene polymer was manufactured in the same manner as in Example 1, except that 1.2 mmol of the compound represented by the chemical formula 1-4 manufactured in Manufacturing Example 4 was added instead of the compound represented by the chemical formula 1-1 to carry out the modification reaction.

Example 5

In Example 1, a modified conjugated diene polymer was manufactured in the same manner as in Example 1, except that 1.2 mmol of the compound represented by the chemical formula 1-5 manufactured in Preparation Example 5 was added instead of the compound represented by the chemical formula 1-1 to carry out the modification reaction.

Example 6

In Example 1, a modified conjugated diene polymer was manufactured in the same manner as in Example 1, except that 1.2 mmol of the compound represented by the chemical formula 1-6 manufactured in Preparation Example 6 was added instead of the compound represented by the chemical formula 1-1 to carry out the modification reaction.

Comparative Example 1

A 20 L autoclave reactor was charged with 100 g of styrene, 880 g of 1,3-butadiene, 5,000 g of n-hexane, and 0.70 g of 2,2-di(2-tetrahydrofuryl)propane as a polar additive, and the internal temperature of the reactor was increased to 50°C. When the internal temperature of the reactor reached 50°C, 3.0 mmol of n-butyllithium was added as a polymerization initiator, and an adiabatic temperature-raising reaction was performed. After 20 minutes, 20 g of 1,3-butadiene was added, and the ends of the polymer chains were capped with butadiene. After 5 minutes, 0.8 mmol of SiCl ₄ was added as a coupling agent, and the reaction was performed for 15 minutes. Afterwards, the polymerization reaction was stopped using ethanol, and 45 ml of a solution containing 0.3 wt% IR1520 (BASF), an antioxidant, dissolved in n-hexane, was added. The resulting polymer was placed in hot water heated by steam and stirred to remove the solvent, thereby producing an unmodified conjugated diene polymer.

Comparative Example 2

In Example 1, except that N ¹ ,N ¹ ,N ³ ,N ³ -tetrakis(3-(trimethoxysilyl)propyl)propan-1,3-diamine was used as a modifier, the ^same procedure as in Example 1 was repeated to produce a ^modified conjugated diene polymer. Here, ^{the N 1 ,} N ¹ ,N ³ ,N ³ -tetrakis(3-(trimethoxysilyl)propyl)propan-1,3-diamine was produced and used with reference to the contents of JP 2019-14014 B2 ⁽ 2019. 11. 15.).

Experimental Example 1

For each modified or unmodified conjugated diene polymer manufactured in the above examples and comparative examples, the styrene unit content and vinyl content in the polymer, as well as the weight average molecular weight (Mw, X10 ³ g/mol), molecular weight distribution (PDI, MWD), and Mooney stress relaxation rate were measured. The results are shown in Table 1 below.

1) Styrene units and vinyl content (weight %)

The styrene unit (SM) and vinyl content in each of the above polymers were measured and analyzed using a Varian VNMRS 500 MHz NMR.

In the NMR measurement, 1,1,2,2-tetrachloroethane was used as the solvent, and the solvent peak was calculated as 5.97 ppm. 7.2–6.9 ppm was the peak of random styrene, 6.9–6.2 ppm was the peak of block styrene, 5.8–5.1 ppm was the peak of 1,4-vinyl, and 5.1–4.5 ppm was the peak of 1,2-vinyl, and thus the styrene unit and vinyl content were calculated.

2) Weight average molecular weight (Mw, X10 ³ g/mol), molecular weight distribution (PDI, MWD)

The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured through GPC (Gel permeation chromatography) analysis, and the molecular weight distribution (PDI, MWD, Mw/Mn) was calculated from the measured molecular weights. Specifically, the GPC was performed by combining two PLgel Olexis (Polymer Laboratories) columns and one PLgel mixed-C (Polymer Laboratories) column, and PS (polystyrene) was used as the GPC standard material when calculating the molecular weight. The GPC measurement solvent was prepared by mixing 2 wt% of an amine compound into tetrahydrofuran.

3) Muni stress relaxation rate

Using the Large Rotor of Monsanto MV2000E, under the conditions of 140℃ and Rotor Speed 2±0.02 rpm, the polymer was left at room temperature (23±5℃) for more than 30 minutes, 27±3 g was sampled, filled into the die cavity, and the platen was operated to apply torque while measuring Mooney viscosity. The slope value of the Mooney viscosity change that appears when the torque is released was measured, and its absolute value was defined as the Mooney stress relaxation ratio.

division Example Comparative example 1 2 3 4 5 6 1 2 NMR
(weight%) SM 10 10 10 10 10 10 10 10 Vinyl 38 38 38 38 38 38 38 38 GPC Mw(X10 ³ g/mol) 2108 2284 2146 2284 1601 1643 1547 1577 Mn(X10 ³ g/mol) 1301 1377 1328 1369 979 998 967 997 PDI 1.62 1.66 1.62 1.67 1.64 1.65 1.60 1.58 Muni stress relaxation rate 0.1214 0.1077 0.1196 0.1026 0.1476 0.1397 0.1607 0.1555

As shown in Table 1 above, the modified conjugated diene polymers of Examples 1 to 6 prepared using the modifier represented by Chemical Formula 1 of the present invention showed increased molecular weights and decreased Mooney stress relaxation rates compared to the unmodified conjugated diene polymer Comparative Example 1 and the modified conjugated diene polymer of Comparative Example 2 prepared using a modifier having a structure different from that of the modifier represented by Chemical Formula 1 but including an amine group and an alkoxysilane group. From the decrease in the Mooney stress relaxation rates, it was confirmed that the modified conjugated diene polymers of Examples 1 to 6 had a highly branched structure compared to Comparative Examples 1 and 2.

The above results mean that the modified conjugated diene polymer according to the present invention can have a high molecular weight and a highly branched structure by being manufactured using a modifier represented by the chemical formula 1.

Experimental example 2

In order to compare and analyze the properties of the rubber compositions containing each modified or unmodified conjugated diene polymer manufactured in the above examples and comparative examples and the molded articles manufactured therefrom, the tensile properties and viscoelastic properties were measured respectively, and the results are shown in Table 3 below.

1) Manufacturing of rubber specimens

Each modified or unmodified conjugated diene polymer of the examples and comparative examples was mixed as raw rubber under the mixing conditions shown in Table 2 below. The contents of the raw materials in Table 2 are each part by weight based on 100 parts by weight of the raw rubber.

division raw material Content (weight parts) Stage 1 Mixing rubber 100 Silica 70 Coupling agent (X50S) 11.2 Fair trade 37.5 Zinc oxide 3 Stearic acid 2 Antioxidant 2 Anti-aging agent 2 Wax 1 2nd stage mixing sulfur 1.5 Rubber accelerator 1.75 Vulcanization accelerator 2

Specifically, the above rubber specimen is mixed through first-stage mixing and second-stage mixing. In the first-stage mixing, a semi-automatic mixer equipped with a temperature control device was used to mix raw rubber, silica (filler), an organosilane coupling agent (X50S, Evonik), a process oil (TDAE oil), a zincating agent (ZnO), stearic acid, an antioxidant (TMQ (RD) (2,2,4-trimethyl-1,2-dihydroquinoline polymer), an anti-aging agent (6PPD ((dimethylbutyl)-N-phenyl-phenylenediamine)), and wax (Microcrystaline Wax). At this time, the initial temperature of the mixer was controlled to 70°C, and after mixing was completed, the first mixture was obtained at a discharge temperature of 145°C to 155°C. In the second-stage mixing, the first mixture was cooled to room temperature, and then the first mixture, sulfur, a rubber accelerator (DPD (diphenylguanine)), and A vulcanization accelerator (CZ (N-cytohexyl-2-benzothiazylsulfenamide)) was added and mixed at a temperature of 100°C or lower to obtain a secondary compound. Afterwards, a rubber specimen was manufactured through a curing process at 160°C for 20 minutes.

2) Tensile properties

Tensile properties were measured by manufacturing each test piece according to the tensile test method of ASTM 412, and measuring the tensile strength at the time of cutting and the tensile stress at 300% elongation (300% modulus) of the test piece. Specifically, the tensile properties were measured at room temperature at a speed of 50 cm/min using a Universal Test Machin 4204 (Instron) tensile tester. The results in Table 3 are expressed as an index based on Comparative Example 1, and a higher value indicates better performance.

3) Viscoelastic properties

Viscoelastic properties were measured for viscoelastic behavior for dynamic deformation at a frequency of 10 Hz and each measurement temperature (-60℃ to 60℃) using a dynamic mechanical analyzer (GABO Corporation) in Film Tension mode, and the tan δ value was confirmed. In the measurement results, the higher the low-temperature 0℃ tan δ value, the better the wet road resistance, and the lower the high-temperature 60℃ tan δ value, the less hysteresis loss and the better the rolling resistance characteristics (fuel efficiency). However, since the results in Table 3 are expressed as an index based on Comparative Example 1, a higher value indicates better.

4) Wear resistance (DIN wear test)

For each rubber specimen, a DIN abrasion test was performed according to ASTM D5963, and the DIN wt loss index (loss volume index): ARIA (Abration resistance index, Method A) was expressed. A higher value indicates better performance.

division Example Comparative example 1 2 3 4 5 6 1 2 Tensile properties
(Index, %) tensile strength 109 108 110 114 114 112 100 107 300% modulus 114 117 120 120 117 119 100 114 Viscoelastic properties
(Index, %) tan δ
(at 0℃) 102 101 107 106 103 107 100 101 tan δ
(at 60℃) 122 123 129 131 121 124 100 114 My wear resistance 119 119 124 122 116 114 100 108

As shown in Table 3 above, Examples 1 to 6 according to one embodiment of the present invention were all excellent in balance in tensile properties, viscoelastic properties, and wear resistance compared to Comparative Examples 1 and 2.

At this time, Examples 1 to 6 were manufactured by a modification reaction with a modifier represented by Chemical Formula 1, and Comparative Examples 1 and 2 were manufactured by a modification reaction with a modifier that is unmodified or has an amine group and an alkoxysilane group but has a structure different from that of the modifier represented by Chemical Formula 1 presented in the present invention.

The results in Tables 1 and 3 above mean that the modified conjugated diene copolymer of the present invention can have a highly branched structure and a high molecular weight by being manufactured using a modifier represented by Chemical Formula 1, and thus has the effect of significantly improving wear resistance, and at the same time, by including a functional group derived from the modifier, it has excellent affinity with a filler, so that the compounding processability can be improved, and thus the tensile properties and viscoelastic properties can be excellent in a balanced manner.

Claims (14)

A modified conjugated diene polymer comprising a repeating unit derived from a conjugated diene monomer and a functional group derived from a modifier represented by the following chemical formula 1:
[Chemical Formula 1]

In the above chemical formula 1,
R ₁ to R ₈ are independently an alkylene group having 1 to 20 carbon atoms or an alkenylene group having 2 to 20 carbon atoms, which is unsubstituted or substituted with a substituent, wherein the substituent is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,
A ₁ to A ₄ are substituents independently represented by the following chemical formula a,
[chemical formula a]

In the above chemical formula a,
R ₉ to R ₁₁ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, wherein at least one of R ₉ to R ₁₁ is an alkoxy group having 1 to 20 carbon atoms.
In the first paragraph,
In the above chemical formula 1, R ₁ to R ₈ are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, and A ₁ to A ₄ are each independently a substituent represented by the following chemical formula a,
A modified conjugated diene polymer in the above chemical formula a, wherein R ₉ to R ₁₁ are each independently an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and at least one is an alkoxy group.
In the first paragraph,
A modified conjugated diene polymer, wherein the modifying agent represented by the chemical formula 1 contains 8 to 12 alkoxy groups in the molecule.
In the first paragraph,
A modified conjugated diene polymer, wherein the modifier represented by the chemical formula 1 is at least one compound selected from compounds represented by the following chemical formulas 1-1 to 1-6:
[Chemical Formula 1-1]

[Chemical Formula 1-2]

[Chemical Formula 1-3]

[Chemical Formula 1-4]

[Chemical Formula 1-5]

[Chemical Formula 1-6]

In the above chemical formulas 1-1 to 1-6,
Me is a methyl group and Et is an ethyl group.
In the first paragraph,
A modified conjugated diene polymer having a weight average molecular weight of 1,200,000 to 3,000,000 g/mol.
In the first paragraph,
A modified conjugated diene polymer having a Mooney stress relaxation rate of 0.050 to 0.150 measured at 140°C.
In the first paragraph,
A modified conjugated diene polymer further comprising a repeating unit derived from an aromatic vinyl monomer.
A step (S1) of producing an active polymer by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in the presence of a polymerization initiator in a hydrocarbon solvent; and
A method for producing a modified conjugated diene polymer of claim 1, comprising the step (S2) of reacting the active polymer with a modifier represented by the following chemical formula 1:
[Chemical Formula 1]

In the above chemical formula 1,
R ₁ to R ₈ are independently an alkylene group having 1 to 20 carbon atoms or an alkenylene group having 2 to 20 carbon atoms, which is unsubstituted or substituted with a substituent, wherein the substituent is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,
A ₁ to A ₄ are substituents independently represented by the following chemical formula a,
[chemical formula a]

In the above chemical formula a,
R ₉ to R ₁₁ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, wherein at least one of R ₉ to R ₁₁ is an alkoxy group having 1 to 20 carbon atoms.
In Article 8,
A method for producing a modified conjugated diene polymer, wherein the modifying agent represented by the chemical formula 1 is at least one compound selected from compounds represented by the chemical formulas 1-1 to 1-6 below:
[Chemical Formula 1-1]

[Chemical Formula 1-2]

[Chemical Formula 1-3]

[Chemical Formula 1-4]

[Chemical Formula 1-5]

[Chemical Formula 1-6]

In the chemical formulas 1-1 to 1-6 above,
Me is a methyl group and Et is an ethyl group.
In Article 8,
A method for producing a modified conjugated diene polymer, wherein the polymerization initiator is used in an amount of 0.01 mmol to 10 mmol based on 100 g of a conjugated diene monomer.
In Article 8,
A method for producing a modified conjugated diene polymer, wherein the above-mentioned modifier is used in an amount of 0.1 mol to 10 mol based on 1 mol of the polymerization initiator.
In Article 8,
A method for producing a modified conjugated diene polymer, wherein the polymerization in the above step (S1) is performed further using a polar additive.
A rubber composition comprising a modified conjugated diene polymer of claim 1 and a filler.
In Article 13,
A rubber composition comprising 0.1 to 200 parts by weight of a filler based on 100 parts by weight of the above-mentioned modified conjugated diene polymer.