Coupling agent for rubber composition, preparation method therefor, and rubber composition containing same

Abstract

A coupling agent for a rubber composition is disclosed. The disclosed coupling agent for a rubber composition is represented by chemical formula 1 or chemical formula 2. [Chemical formula 1] [Chemical formula 2] [In chemical formula 1 and chemical formula 2, R1 to R4 are each independently selected from the group consisting of an alkyl group, an aryl group and an arylamino group, R1 and R2, or R3 and R4 can optionally bind to form a ring, R5 is selected from the group consisting of an alkyl group, an aryl group, an amino group, an alkylamino group and an arylamino group, L1 and L3 are selected from the group consisting of a direct bond, an alkylene group and an arylene group, L2 is a direct bond, -NH- or -O-, n is 0, 1 or 2, and m is 1 or an integer of 2-100,000.

Description

Coupling agent for rubber composition, method for producing same, and rubber composition comprising same

[0001] The present invention relates to a coupling agent for a rubber composition, a method for producing the same, and a rubber composition comprising the same, and more particularly, to a coupling agent for a rubber composition capable of improving the reinforcing performance of carbon black used as a reinforcing agent, a method for producing the same, and a rubber composition comprising the same.

[0002] Pneumatic tires are installed on vehicles and play a vital role in supporting loads, absorbing and alleviating road shocks, transmitting engine drive and braking power, and changing and maintaining direction. The rubber composition of a tire is divided into the tread that comes into contact with the ground and the casing that supports the structure, and it greatly affects the performance of the tire. Carbon black and silica are commonly used as reinforcing agents to improve the performance of the rubber composition for tires. Rubber compositions containing carbon black as a reinforcing agent have excellent wear resistance and reinforcing properties (modulus), while rubber containing silica as a reinforcing agent has the advantages of low rolling resistance, resulting in fuel efficiency characteristics and excellent braking performance on wet roads.

[0003] One of the most significant recent paradigm shifts in the automotive industry is environmental friendliness. Due to strengthening greenhouse gas emissions regulations in each country, automotive development trends are gradually shifting from internal combustion engine vehicles to electric vehicles. As automakers focus their capabilities on EV development and investment, the global EV market is expanding, and tires with performance capabilities suited to EVs are also in demand. Due to the limited battery capacity of EVs, securing low rolling resistance (LRR) tires is essential to ensure long driving range. Furthermore, improved wear resistance is essential to withstand the high torque and high loads exerted on the motor and battery during initial acceleration due to the characteristics of electric motors.

[0004] To improve the LRR and wear resistance of tires, the most common method is to apply new materials such as functional polymers to enhance the bonding strength between the rubber and the reinforcing agent. Among these, the technology that bonds the rubber and the reinforcing agent is called coupling technology, and the substance that induces the bonding between the rubber and the reinforcing agent through chemical and physical bonding is called a coupling agent. Coupling agent technology is generally used when using hydrophilic silica, which is difficult to disperse in a hydrophobic rubber matrix, as a reinforcing agent. In the case of bis(triethoxysilylpropyl)tetrasulfide (TESPT, Si-69), it is one of the most easily found coupling agents in the tire industry because it has a silanol group that can bond with silica and a tetrasulfide structure that can bond with rubber.

[0005] In contrast, carbon black, unlike silica, has a hydrophobic surface. Therefore, when used as a reinforcing agent, it can be dispersed within a hydrophobic rubber matrix without the need for a coupling agent. Consequently, there has been limited demand for coupling agent technology. However, rubber compositions for electric vehicle tires, as mentioned above, must exhibit superior performance in harsh environments compared to conventional rubber compositions. Therefore, there is a growing need for technology to develop a coupling agent for carbon black that can simultaneously improve both LRR and wear resistance.

[0006] The present embodiment aims to provide a coupling agent for a rubber composition and a method for producing the same, which can improve the dispersibility of carbon black as a filler in the rubber composition.

[0007] The present embodiment aims to provide a rubber composition capable of having low rolling resistance characteristics and excellent wear resistance by including a coupling agent capable of inducing interaction between raw rubber and carbon black in the rubber composition.

[0008] According to one aspect of the present invention, a coupling agent for a rubber composition comprising a compound represented by Chemical Formula 1 or Chemical Formula 2 is provided.

[0009] [Chemical Formula 1]

[0010]

[0011] [Chemical Formula 2]

[0012]

[0013] [In the above chemical formulas 1 and 2, R1 to R4 are each independently selected from the group consisting of an alkyl group, an aryl group, and an arylamino group; R1 and R2, or R3 and R4, may optionally combine to form a ring; R5 is selected from the group consisting of an alkyl group, an aryl group, an amino group, an alkylamino group, and an arylamino group; L1 and L3 are selected from the group consisting of a direct bond, an alkylene group, and an arylene group; L2 is a direct bond or -NH- or -O-; n is 0 or 1 or 2; and m is an integer of 1 or 2 to 100,000.]

[0014] In the above chemical formula 1, n is 1; m is 1; L1 and L3 are selected from the group consisting of a direct bond, a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms, and a substituted or unsubstituted arylene group having 6 to 30 carbon atoms; and L2 may be a direct bond.

[0015] In the above chemical formula 1, n is 1; m is 1; L1 and L3 are substituted or unsubstituted alkylene groups having 1 to 30 carbon atoms; and L2 may be -NH- or -O-.

[0016] The above coupling agent may have a molecular weight of 1,000,000 g / mol or less.

[0017] According to another aspect of the present invention, a method for producing a coupling agent for a rubber composition is provided, comprising the steps of: a) reacting a ketone compound and a nitrogen compound in the presence of an aromatic solvent; b) cooling the obtained reactant to room temperature and then extracting the solution; and c) drying and then distilling the obtained extract.

[0018] The above step a) can be performed at 100 to 150°C for 10 to 100 hours.

[0019] The nitrogen compound may be included in an amount of 5 to 90 parts by weight based on 100 parts by weight of the ketone compound.

[0020] The above ketone compound may include at least one selected from the group consisting of aromatic ketones, cyclic ketones, aliphatic ketones and derivatives thereof.

[0021] The above nitrogen compound may include at least one selected from the group consisting of diamines, triamines, aromatic amines, hydrazine compounds and derivatives thereof.

[0022] According to another aspect of the present invention, a rubber composition comprising raw rubber; carbon black; and a coupling agent according to an aspect of the present invention is provided.

[0023] The present embodiment provides a coupling agent for a rubber composition capable of improving the dispersibility of carbon black as a filler in the rubber composition and a method for producing the same.

[0024] The present embodiment provides a rubber composition capable of having low rolling resistance characteristics and excellent wear resistance by including a coupling agent capable of inducing interaction between raw rubber and carbon black in the rubber composition.

[0025] FIGS. 1 to 10 are drawings each showing the NMR (Nuclear Magnetic Resonance) measurement results for compounds 1 to 10 synthesized according to the first to tenth synthesis examples of the present invention.

[0026] Hereinafter, the present embodiment will be described in detail with reference to the attached drawings. The following embodiments are presented to sufficiently convey the spirit of the present invention to those skilled in the art.

[0027] In the notation of groups (atomic groups) in this specification, a notation that does not describe substitution and unsubstitution includes those with substituents as well as those without substituents. For example, "alkyl group" includes not only an alkyl group without a substituent (an unsubstituted alkyl group) but also an alkyl group with a substituent (a substituted alkyl group).

[0028] The coupling agent for a rubber composition according to the present invention comprises a compound represented by the following chemical formula 1 or chemical formula 2.

[0029] [Chemical Formula 1]

[0030]

[0031] In the above chemical formula 1, R1 to R4 are independently selected from the group consisting of an alkyl group, an aryl group, and an arylamino group.

[0032] The alkyl group is a substituted or unsubstituted straight-chain or branched-chain alkyl group having 1 to 30 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.

[0033] An aryl group is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and aryl groups include phenyl, naphthyl, etc.

[0034] The arylamino group is a substituted or unsubstituted arylamino group having 6 to 30 carbon atoms.

[0035] R1 and R2, or R3 and R4, may optionally combine to form a ring. Preferred examples include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group.

[0036] L1 and L3 are selected from the group consisting of a direct bond, an alkylene group, and an arylene group.

[0037] The alkylene group is a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms, and may include a methylene group, an ethylene group, a trimethylene group, a propylene group, or a butylene group.

[0038] The arylene group is a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, and may include a phenylene group or a naphthalene group.

[0039] L2 is a direct bond or -NH- or -O-, n is 0 or 1 or 2, and m is an integer from 1 or 2 to 100,000.

[0040] As a preferred example of the present invention, in chemical formula 1, n is 1; m is 1; L1 and L3 are selected from the group consisting of a direct bond, a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms, and a substituted or unsubstituted arylene group having 6 to 30 carbon atoms; and L2 may be a direct bond.

[0041] More specifically, L1 and L3 may be substituted or unsubstituted alkylene groups having 1 to 30 carbon atoms, for example, a methylene group, an ethylene group, a trimethylene group, a propylene group, a butylene group, or may include substituted or unsubstituted arylene groups having 6 to 30 carbon atoms, for example, a phenylene group, a naphthalene group. In this case, a case where one of L1 and L3 is a direct bond is also included.

[0042] In another preferred example of the present invention, in chemical formula 1, n is 1; m is 1; L1 and L3 are substituted or unsubstituted alkylene groups having 1 to 30 carbon atoms; and L2 may be -NH- or -O-. In this case, the alkylene group may be selected from the group consisting of a methylene group, an ethylene group, a trimethylene group, a propylene group, and a butylene group.

[0043] Hereinafter, chemical formula 2 will be explained.

[0044] [Chemical Formula 2]

[0045]

[0046] In chemical formula 2, R1 and R2 are the same as described above, and R5 is selected from the group consisting of an alkyl group, an aryl group, an amino group, an alkylamino group, and an arylamino group.

[0047] The alkyl group is a substituted or unsubstituted straight-chain or branched-chain alkyl group having 1 to 30 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.

[0048] An aryl group is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and aryl groups include phenyl, naphthyl, etc.

[0049] The alkylamino group is a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms.

[0050] The arylamino group is a substituted or unsubstituted arylamino group having 6 to 30 carbon atoms.

[0051] The coupling agent for the rubber composition according to one embodiment of the present invention may have a molecular weight of 1,000,000 g / mol or less, preferably 500,000 g / mol or less, more preferably 100,000 g / mol or less.

[0052] The coupling agent for a rubber composition according to the present invention can induce a reaction with carbon black and raw rubber monomers used as reinforcing agents, in particular, by including an imine group, thereby improving the low rolling resistance and wear resistance performance of a rubber composition including the same.

[0053] The present invention also provides a method for producing a coupling agent for a rubber composition.

[0054] First, in step a), a ketone compound and a nitrogen compound are reacted in the presence of an aromatic solvent.

[0055] The ketone compound includes at least one selected from the group consisting of aromatic ketones, cycloalkyl ketones, aliphatic ketones, and derivatives thereof.

[0056] The aromatic ketone may include at least one selected from the group consisting of benzophenone, acetophenone, and anthraquinone, and the cycloadditional ketone may include at least one selected from the group consisting of adamantanone, methyladamantanone, and dimethyladamantanone.

[0057] Aliphatic ketones include 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,3-dimethyl-2-hexanone, 2-pentanone, 3-pentanone, 2,4-dimethyl-3-pentanone, 2-hexanone, 4-methyl-2-hexanone, 5-methyl-2-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, It may include at least one selected from the group consisting of 3-octanone, 4-octanone, nonanone, and decanone.

[0058] As a preferred example of the present invention, the ketone compound may include at least one selected from the group consisting of benzophenone, its derivatives Michler's ketone, 2-adamantanone, and 2,4-dimethyl-3-pentanone.

[0059] The nitrogen compound comprises at least one selected from the group consisting of diamines, triamines, aromatic amines, hydrazine compounds and derivatives thereof.

[0060] The diamine may include at least one selected from the group consisting of ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, and 2,5-dimethyl-2,5-hexanediamine.

[0061] Triamines may include diethylenetriamine.

[0062] The aromatic amine may include one or more selected from the group consisting of aniline, p-methoxyaniline, o-, m- or p-toluidine, 2,4- and 2,6-toluenediamine and m- or p-phenylenediamine.

[0063] The hydrazine compound may include at least one selected from the group consisting of hydrazine, methylhydrazine, and phenylhydrazine.

[0064] In a preferred embodiment of the present invention, the nitrogen compound may include at least one selected from the group consisting of 1,6-diaminohexane, diethylenetriamine, aniline, phenylenediamine, and phenylhydrazine.

[0065] a) In step a, it is advantageous to react 5 to 90 parts by weight, preferably 10 to 80 parts by weight, of a nitrogen compound with respect to 100 parts by weight of a ketone compound at a reaction temperature of 100 to 150°C, preferably 110 to 140°C, for 10 to 100 hours. At this time, toluene can be used as an organic solvent.

[0066] In step b), the reactant obtained in step a) is cooled to room temperature and then the solution is extracted. The extraction solution may be an aqueous solution containing diethyl ether and sodium carbonate, but is not limited thereto. The extraction method is performed using a method commonly used in the art.

[0067] In step c), the obtained extract is dried and then distilled. The distillation method may be a reduced pressure distillation method, and preferably, first reduced pressure distillation is performed followed by reduced pressure filtration and second reduced pressure distillation.

[0068] The coupling agent for a rubber composition manufactured according to the present invention can induce a reaction with carbon black and raw rubber monomers used as a reinforcing agent, in particular, by including an imine group, thereby improving the low rolling resistance and wear resistance performance of a rubber composition including the same.

[0069] The present invention also provides a rubber composition comprising a coupling agent according to one embodiment of the present invention.

[0070] The rubber composition is composed of raw rubber, carbon black, and a coupling agent.

[0071] The raw rubber may include at least one selected from isoprene rubber and isoprene rubber and diene rubber.

[0072] Isoprene rubber may include natural rubbers such as, for example, deproteinized natural rubber and high-purity natural rubber, or modified natural rubbers such as, for example, epoxidized natural rubber, hydrogenated natural rubber, and grafted natural rubber.

[0073] The diene rubber may include, for example, styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene-containing styrene butadiene rubber or nitrile-containing styrene butadiene rubber.

[0074] In addition to the raw rubber described above, neoprene rubber, chlorobutyl rubber, or bromobutyl rubber may also be used.

[0075] Carbon black that can be used includes furnace black, acetylene black, thermal black, and channel black.

[0076] The coupling agent is the same as described above.

[0077] The rubber composition according to the present invention may contain 10 to 80 parts by weight, preferably 20 to 70 parts by weight, and more preferably 30 to 60 parts by weight, of carbon black, based on 100 parts by weight of raw rubber, and may contain less than 5 parts by weight, preferably 0.5 to 3 parts by weight, and more preferably 1 to 2 parts by weight, of a coupling agent.

[0078] By satisfying the above-described conditions, the coupling promotion effect between the raw rubber and carbon black by the coupling agent according to the present invention is maximized, so that the carbon black can be sufficiently dispersed in the rubber composition without generating by-products.

[0079] The rubber composition according to one embodiment of the present invention may further include a reinforcing agent such as silica, clay, or talc, and may further include additives such as a vulcanizing agent such as sulfur, a vulcanization accelerator such as sulfenamide, a vulcanization accelerator assistant such as zinc oxide or magnesium oxide, a process oil such as naphthenic oil or aromatic oil, a dispersing agent (wax) such as stearic acid, an anti-aging agent, an antioxidant, an ozone cracking inhibitor, a peptizing agent, an adhesive resin, a vulcanization retardant, and the like, within a range that does not affect the coupling interaction between the raw rubber and the carbon black by the coupling agent.

[0080] The rubber composition manufactured according to one embodiment of the present invention can be applied not only to a rubber composition for tires, but also to a rubber composition for a casing (sidewall, wing, base tread, sidewall packing, breaker cushion, etc.) into which carbon black is introduced.

[0081] Hereinafter, the present invention will be described in detail through examples. However, these examples are provided to explain the present invention in more detail, and the scope of the present invention is not limited by the following examples.

[0082] Example

[0083] 1. Synthesis of coupling agent

[0084] Synthesis Example 1:

[0085] Compound 1 was synthesized according to the following reaction scheme.

[0086]

[0087] In a round-bottom flask made of tempered glass, 50 g of benzophenone, 15.9 g of 1,6-diaminohexane, and 7.1 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 350 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the specified period of time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed by distillation under reduced pressure. The remaining reactant was removed by distillation to obtain compound 1. The structure of the obtained compound 1 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 1.

[0088] Synthesis Example 2:

[0089] Compound 2 was synthesized according to the following reaction scheme.

[0090]

[0091] In a round-bottom flask made of tempered glass, 10 g of benzophenone, 2.84 g of diethylenetriamine, and 0.19 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed by distillation under reduced pressure. The remaining reactant was removed by distillation to obtain compound 2. The structure of the obtained compound 2 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Fig. 2.

[0092] Synthesis Example 3:

[0093] Compound 3 was synthesized according to the following reaction scheme.

[0094]

[0095] In a round-bottom flask made of tempered glass, 10 g of benzophenone, 5.64 g of aniline, and 1.57 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. Compound 3 was obtained by washing with methanol. The structure of the obtained compound 3 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Fig. 3.

[0096] Synthesis Example 4:

[0097] Compound 4 was synthesized according to the following reaction scheme.

[0098]

[0099] In a round-bottom flask made of tempered glass, 10 g of benzophenone, 6.54 g of phenylhydrazine, and 1.57 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed by distillation under reduced pressure. Compound 4 was obtained by washing with methanol. The structure of the obtained compound 4 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Fig. 4.

[0100] Synthesis Example 5:

[0101] Compound 5 was synthesized according to the following reaction scheme.

[0102]

[0103] In a round-bottom flask made of tempered glass, 10.7 g of Michler's ketone, 4.65 g of 1,6-diaminohexane, and 0.76 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 300 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The dissolved solvent was filtered under reduced pressure using benzene. The filtrate was distilled under reduced pressure to obtain compound 5. The structure of the obtained compound 5 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Fig. 5.

[0104] Synthesis Example 6:

[0105] Compound 6 was synthesized according to the following reaction scheme.

[0106]

[0107] In a round-bottom flask made of tempered glass, 10 g of 2-adamantanone, 3.86 g of 1,6-diaminohexane, and 0.23 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and sodium carbonate aqueous solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The remaining reactant was removed using distillation to obtain compound 6. The structure of the obtained compound 6 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 6.

[0108] Synthesis Example 7:

[0109] Compound 7 was synthesized according to the following reaction scheme.

[0110]

[0111] In a round-bottom flask made of tempered glass, 27.6 g of 2,4-dimethyl-3-pentanone, 5.63 g of 1,6-diaminohexane, and 0.46 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the specified period of time. After cooling to room temperature, the mixture was extracted with diethyl ether and sodium carbonate aqueous solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The remaining reactant was removed using a vacuum pump to obtain compound 7. The structure of the obtained compound 7 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 7.

[0112] Synthesis Example 8:

[0113] Compound 8 was synthesized according to the following reaction scheme.

[0114]

[0115] In a round-bottom flask made of tempered glass, 21.1 g of 2,4-dimethyl-3-pentanone, 3.82 g of diethylenetriamine, and 0.35 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 150 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the specified period of time. After cooling to room temperature, the mixture was extracted with diethyl ether and sodium carbonate aqueous solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The remaining reactant was removed using a vacuum pump to obtain compound 8. The structure of the obtained compound 8 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 8.

[0116] Synthesis Example 9:

[0117] Compound 9 was synthesized according to the following reaction scheme.

[0118]

[0119] In a round-bottom flask made of tempered glass, 47.5 g of 2,4-dimethyl-3-pentanone, 9 g of p-phenylenediamine, and 3.16 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 300 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The dissolved solvent was filtered under reduced pressure using acetonitrile. The filtrate was distilled under reduced pressure to obtain compound 9. The structure of the obtained compound 9 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 9.

[0120] Synthesis Example 10:

[0121] Compound 10 was synthesized according to the following reaction scheme.

[0122]

[0123] In a round-bottom flask made of tempered glass, 47.5 g of 2,4-dimethyl-3-pentanone, 9 g of p-phenylenediamine, and 3.16 g of p-toluenesulfonic acid were each added at room temperature and dissolved in 300 g of toluene. A Dean-Stark trap was then installed. The temperature was then raised to 125°C and the reaction was carried out for the indicated time. After cooling to room temperature, the mixture was extracted with diethyl ether and an aqueous sodium carbonate solution. The separated organic layer was dried over magnesium sulfate and the organic solvent was removed using reduced pressure distillation. The undissolved solid was filtered under reduced pressure using acetonitrile to obtain compound 10. The structure of the obtained compound 10 was confirmed through NMR (Nuclear Magnetic Resonance) measurement, as shown in Figure 10.

[0124] 2. Manufacture of rubber composition

[0125] (Example 1)

[0126] For 100 parts by weight of raw rubber, 45 parts by weight of carbon black, 1.5 parts by weight of compound 1 prepared in Synthesis Example 1 as a coupling agent, 4 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 1 part by weight of an antioxidant were mixed at 160°C for 1 minute, and after releasing at 165°C, 1.7 parts by weight of sulfur and 1.3 parts by weight of a vulcanization accelerator were added at 105°C for a second mixing to prepare a rubber composition. At this time, the raw rubber used was a 1:1 mixture of natural rubber and butadiene rubber.

[0127] (Examples 2 to 10)

[0128] A rubber composition was manufactured in the same manner as in Example 1 above, except that compounds 2 to 10, each synthesized according to Synthesis Examples 2 to 10, were used instead of compound 1 as a coupling agent.

[0129] (Comparative Example 1)

[0130] A rubber composition was manufactured in the same manner as in Example 1 above, except that no coupling agent was used.

[0131] (Comparative Example 2)

[0132] A rubber composition was manufactured in the same manner as in Example 1 above, except that a compound represented by the following chemical formula 3 was used as a coupling agent.

[0133] [Chemical Formula 3]

[0134]

[0135] (Comparative Example 3)

[0136] A rubber composition was manufactured in the same manner as in Example 1 above, except that a compound represented by the following chemical formula 4 was used as a coupling agent.

[0137] [Chemical Formula 4]

[0138]

[0139] Evaluation example: Physical property and performance evaluation

[0140] Physical properties and performance evaluations were performed on rubber specimens manufactured from rubber compositions manufactured according to Examples 1 to 10 and Comparative Examples 1 to 3, and the results are shown in Table 1 below.

[0141]

[0142] - Mooney viscosity (ML1+4, 100℃) was measured according to ASTM D1646. Mooney viscosity is a value indicating the viscosity of unvulcanized rubber. The lower the value, the better the processability of the unvulcanized rubber.

[0143] - Hardness (Shore A) was measured according to DIN 53505. Hardness indicates steering stability, and a higher value indicates better steering stability.

[0144] - 100% modulus, 300% modulus and elongation were measured according to ISO 37 standard.

[0145] - Tan δ was measured using a Rheometrics Dynamic Spectrometer.

[0146] As can be seen in Table 1 above, the rubber compositions manufactured according to Examples 1, 2, 5 to 10 of the present invention exhibited higher 100% modulus values ​​and 300% modulus values ​​compared to Comparative Example 1, which did not use a coupling agent. It is believed that these results are due to the enhanced interaction between carbon black and rubber in the rubber composition due to the carbon coupling agent.

[0147] Meanwhile, in the case of the example with improved modulus value, the elongation tends to have a relatively low value because the modulus value is high compared to Comparative Example 1, but it was confirmed that all of them are within a range that does not significantly affect the physical properties of the rubber sheet.

[0148] In the case of Examples 3 and 4, the effect of improving the modulus value due to the terminal structure was minimal compared to the carbon coupling agent with the both terminal structure, but because it could react with the carbon black surface and improve the dispersion of the carbon black, a lower Mooney viscosity and a higher elongation were confirmed compared to the comparative example.

[0149] In addition, in the case of Examples 1, 2, 7 and 8, the degree of interaction between carbon black and rubber differed depending on the presence or absence of an amine group in the carbon coupling agent backbone, resulting in a difference in modulus value.

Claims

1. A coupling agent for a rubber composition comprising a compound represented by the following chemical formula 1 or chemical formula 2: [Chemical Formula 1] [Chemical Formula 2] [In the above chemical formula 1 and chemical formula 2, R1 to R4 are each independently selected from the group consisting of an alkyl group, an aryl group, and an arylamino group; R1 and R2, or R3 and R4 may optionally combine to form a ring; R5 is selected from the group consisting of an alkyl group, an aryl group, an amino group, an alkylamino group, and an arylamino group; L1 and L3 are selected from the group consisting of a direct bond, an alkylene group, and an arylene group; L2 is a direct bond or -NH- or -O-; n is 0 or 1 or 2; m is an integer between 1 and 2, inclusive, and 100,000.] 2. In paragraph 1, In the above chemical formula 1 n is 1; m is 1; L1 and L3 are selected from the group consisting of a direct bond, a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms, and a substituted or unsubstituted arylene group having 6 to 30 carbon atoms; L2 is a coupling agent for a direct bond rubber composition.

3. In paragraph 1, In the above chemical formula 1 n is 1; m is 1; L1 and L3 are substituted or unsubstituted alkylene groups having 1 to 30 carbon atoms; L2 is a coupling agent for a rubber composition having -NH- or -O-.

4. In paragraph 1, The above coupling agent is a coupling agent for a rubber composition having a molecular weight of 1,000,000 g / mol or less. 5.a) A step of reacting a ketone compound and a nitrogen compound in the presence of an aromatic solvent; b) a step of cooling the obtained reactant to room temperature and then extracting the solution; and c) A method for producing a coupling agent for a rubber composition, comprising the step of drying and then distilling the obtained extract.

6. In paragraph 5, A method for producing a coupling agent for a rubber composition, wherein the step a) is performed at 100 to 150°C for 10 to 100 hours.

7. In paragraph 5, A method for producing a coupling agent for a rubber composition comprising 5 to 90 parts by weight of the nitrogen compound relative to 100 parts by weight of the ketone compound.

8. In paragraph 5, A method for producing a coupling agent for a rubber composition, wherein the ketone compound comprises at least one selected from the group consisting of aromatic ketones, cyclic ketones, aliphatic ketones and derivatives thereof.

9. In paragraph 5, A method for producing a coupling agent for a rubber composition, wherein the above nitrogen compound comprises at least one selected from the group consisting of diamine, triamine, aromatic amine, hydrazine compound and derivatives thereof.

10. Raw rubber; carbon black; and A rubber composition comprising a coupling agent according to any one of claims 1 to 4.

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