Antioxidants, their use and sbs thermoplastic elastomers and methods for their preparation

Abstract

The present application relates to the field of SBS thermoplastic elastomer, and discloses an antioxidant for preparing SBS thermoplastic elastomer and SBS thermoplastic elastomer prepared by the method. The antioxidant of the present application contains a compound with the structure shown in formula (I) and a compound with the structure shown in formula (II), wherein n in formula (I) and formula (II) is an integer of 1-16. By using the antioxidant of the present application, the aging performance of SBS thermoplastic elastomer can be significantly improved.

Description

Technical Field

[0001] This invention relates to SBS thermoplastic elastomers, and more specifically, to a novel antioxidant, a method for preparing SBS thermoplastic elastomers using the antioxidant, and the SBS thermoplastic elastomers prepared by the method. Background Technology

[0002] SBS is a widely used thermoplastic elastomer, found in adhesives, road asphalt modification, plastic modification, and footwear manufacturing. However, SBS undergoes aging during storage, and as this process progresses, the performance of SBS and its products gradually declines until they become unusable. To extend the service life of SBS and its products, substances that inhibit the aging process are added to SBS, thus extending their shelf life and overall lifespan. These substances are called antioxidants. Antioxidants are diverse, with varying functions. Based on their primary function, they can be categorized as anti-thermal-oxidative aging agents, anti-ozone agents, harmful metal ion inhibitors, anti-fatigue agents, ultraviolet absorbers, and anti-cracking agents. However, since each protective function is often not specific to a single antioxidant, using a single antioxidant often fails to achieve adequate protection.

[0003] The traditional antioxidant system for SBS consists of a compound of 2,6-di-tert-butyl-4-methylphenol (BHT) and tris(nonylphenyl) phosphite (TNPP) in a 1:1 weight ratio. However, the antioxidant capacity of this system needs further improvement. Additionally, CN103435956A discloses a compound antioxidant composition for thermoplastic styrene-butadiene block copolymers, with an addition amount of 0.2-0.6% of the SBS raw rubber weight. This composition shows a significant improvement in resistance to thermo-oxidative aging compared to traditional antioxidant systems. However, because the antioxidant in this application contains amine antioxidants, its photo-aging performance decreases, necessitating further improvement in its anti-aging properties. Summary of the Invention

[0004] The purpose of this invention is to provide a novel antioxidant for preparing SBS thermoplastic elastomers, a method for preparing SBS thermoplastic elastomers using this antioxidant, and the SBS thermoplastic elastomers prepared by this method. Using this antioxidant can significantly improve the aging performance of SBS thermoplastic elastomers.

[0005] To achieve the above objectives, a first aspect of the present invention provides an antioxidant comprising a compound with the structure shown in formula (I) and a compound with the structure shown in formula (II).

[0006]

[0007] In equations (I) and (II), n is an integer from 1 to 16.

[0008] Preferably, in equations (I) and (II), n is an integer between 10 and 14.

[0009] Preferably, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.02-2:1; more preferably, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.5-1.1:1; even more preferably, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.9-1.1:1.

[0010] A second aspect of the present invention provides a method for preparing SBS thermoplastic elastomer, the method comprising the following steps:

[0011] 1) Under the first anionic polymerization conditions, styrene is polymerized in an inert solvent in the presence of an organolithium initiator, and the conversion rate of styrene reaches more than 95%.

[0012] 2) Under the second anionic polymerization conditions, the reaction mixture obtained in step 1) is polymerized with butadiene;

[0013] 3) Under coupling reaction conditions, the polymerization product obtained in step 2) is reacted with the coupling agent;

[0014] 4) Add a terminator and an antioxidant to the coupling product obtained in step 3);

[0015] The antioxidant is any one of the antioxidants described in claims 1-4.

[0016] Preferably, the amount of antioxidant used is 0.2-0.8 parts by weight relative to 100 parts by weight of polymeric monomer; more preferably, the amount of antioxidant used is 0.2-0.5 parts by weight relative to 100 parts by weight of polymeric monomer; and even more preferably, the amount of antioxidant used is 0.4-0.5 parts by weight.

[0017] Preferably, the first anionic polymerization conditions include: a polymerization initiation temperature of 30-60°C, a pressure of 0.1-0.3 MPa, and a time of 20-30 min.

[0018] Preferably, the second anionic polymerization conditions include: a polymerization initiation temperature of 30-60°C, a pressure of 0.1-0.3 MPa, and a time of 15-30 min.

[0019] Preferably, the organolithium initiator is a compound represented by formula (Ⅲ).

[0020] R3Li formula (Ⅲ),

[0021] In formula (Ⅲ), R3 is a C1-C6 alkyl group, C3 ... 12 cycloalkyl, C7-C 14 Aryl or C6-C 12 Aryl groups.

[0022] Preferably, the coupling agent is a three-arm coupling agent.

[0023] Preferably, the coupling agent is methyltrichlorosilane.

[0024] Preferably, the organolithium initiator is based on lithium, and the molar ratio of the coupling agent to the organolithium initiator is 0.25-0.35:1.

[0025] A third aspect of the present invention provides an SBS thermoplastic elastomer prepared by the above-described preparation method.

[0026] The fourth aspect of this invention provides the application of the antioxidant of this invention in the preparation of SBS thermoplastic elastomers.

[0027] The anti-aging agent provided by this invention can significantly improve the aging performance of low SBS thermoplastic elastomers.

[0028] Furthermore, by using a three-arm coupling agent, the SBS thermoplastic elastomer obtained has a unique star-shaped structure. Moreover, by using the three-arm coupling agent in combination with the antioxidant specific to this invention, the antioxidant properties of the obtained SBS thermoplastic elastomer can be further improved. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] According to a first aspect of the present invention, an antioxidant is provided, wherein the antioxidant comprises a compound with the structure shown in formula (I) and a compound with the structure shown in formula (II).

[0031]

[0032] In equations (I) and (II), n is an integer from 1 to 16.

[0033] Preferably, in formula (I), n is an integer from 10 to 14.

[0034] Preferably, in formula (II), n is an integer from 10 to 14.

[0035] Specific examples of n include: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16.

[0036] Specific examples of compounds with the structure shown in formula (I) include compounds with n ranging from 1 to 16. Among these, compounds with n ranging from 10 to 14 are preferred.

[0037] Specific examples of compounds with the structure shown in formula (II) include compounds with n ranging from 1 to 16. Among these, compounds with n ranging from 10 to 14 are preferred.

[0038] According to the present invention, the relative ratio of the compound with the structure shown in formula (I) and the compound with the structure shown in formula (II) in the antioxidant can be appropriately selected according to the specific application. Taking into account cost factors, generally, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.2-2:1; preferably, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.5-1.1:1; more preferably, the molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.9-1.1:1. Within the above range, by making the molar ratio of the compound with the structure shown in formula (I) 0.5 or more, the anti-aging performance can be further improved. However, when the molar ratio of the compound with the structure shown in formula (I) is 2:1 or more, the cost will increase, and the non-rubber component in the prepared polymer will increase, affecting the performance in the application (e.g., the adhesive performance in the field of waterproof membranes).

[0039] Furthermore, the compounds with the structures shown in formula (I) and (II) above can be prepared by organic synthesis or obtained commercially.

[0040] In a second aspect, the present invention provides a method for preparing an SBS thermoplastic elastomer, the method comprising the following steps:

[0041] 1) Under the first anionic polymerization conditions, styrene is polymerized in an inert solvent in the presence of an organolithium initiator, and the conversion rate of styrene reaches more than 95%.

[0042] 2) Under the second anionic polymerization conditions, the reaction mixture obtained in step 1) is polymerized with butadiene;

[0043] 3) Under coupling reaction conditions, the polymerization product obtained in step 2) is reacted with the coupling agent;

[0044] 4) Add a terminator and an antioxidant to the coupling product obtained in step 3);

[0045] Wherein, the coupling agent is a three-arm coupling agent, and the antioxidant is the antioxidant according to any one of claims 1-4.

[0046] The antioxidant has been described in detail above and will not be repeated here. Furthermore, this invention relates only to improvements in the antioxidant, and there are no particular limitations on the conditions in the above-described method for preparing SBS thermoplastic elastomers; they can be implemented according to conditions known in the art.

[0047] In this invention, the amount of antioxidant can be appropriately selected based on the weight of the polymeric monomers. Generally, relative to 100 parts by weight of the total amount of polymeric monomers (styrene and butadiene), the amount of antioxidant is 0.2-0.8 parts by weight, preferably 0.2-0.5 parts by weight, more preferably 0.3-0.5 parts by weight, and particularly preferably 0.4-0.5 parts by weight.

[0048] According to the present invention, the organolithium initiator can be any organolithium monolithium compound, organolithium dilithium compound, or organolithium polylithium compound commonly used in the field of anionic polymerization that can initiate olefin polymerization, without particular limitation. The organolithium initiator is preferably an organolithium monolithium compound, more preferably a compound represented by formula (III).

[0049] R3Li Formula (III)

[0050] In formula (III), R3 is a C1-C6 alkyl group, C3 ... 12 cycloalkyl, C7-C 14 Aryl or C6-C 12 Aryl groups.

[0051] The C1-C6 alkyl groups include straight-chain alkyl groups of C1-C6 and branched alkyl groups of C3-C6, and specific examples may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, and n-hexyl.

[0052] The C3-C 12 Specific examples of cycloalkyl groups may include, but are not limited to: cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-n-propylcyclohexyl, and 4-n-butylcyclohexyl.

[0053] The C7-C 14 Specific examples of aralkyl groups may include, but are not limited to: phenylmethyl, phenylethyl, phenyl-n-propyl, phenyl-n-butyl, phenyl-tert-butyl, phenylisopropyl, phenyl-n-pentyl, and phenyl-n-butyl.

[0054] The C6-C 12 Specific examples of aryl groups may include, but are not limited to: phenyl, naphthyl, 4-methylphenyl and 4-ethylphenyl.

[0055] The organolithium initiator may be, but is not limited to, one or more of the following: ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, phenyl lithium, 2-naphthyl lithium, 4-butylphenyl lithium, 4-tolyl lithium, cyclohexyl lithium, and 4-butylcyclohexyl lithium, preferably n-butyl lithium and / or sec-butyl lithium, and more preferably n-butyl lithium.

[0056] The present invention does not particularly limit the amount of the organolithium initiator, which can be appropriately selected according to the molecular weight and microstructure of the target polymer. Preferably, the amount of the organolithium initiator relative to 100g of polymerizing monomers (the combined amount of styrene and butadiene) can be 0.5-5 mmol, more preferably 0.5-2 mmol.

[0057] According to the present invention, in step (1), the inert solvent can be any organic substance capable of serving as a reaction medium, for example, it can be a hydrocarbon solvent and / or an ether solvent. The hydrocarbon solvent can be one or more of C5-C7 cycloalkanes, aromatics, and isoalkanes. Specific examples of the hydrocarbon solvent may include, but are not limited to, one or more of benzene, toluene, hexane, cyclohexane, pentane, heptane, hexane, and cyclohexane. The ether solvent can be C4-C... 15 The solvents are monoethers and / or polyethers. Specific examples of the ether solvents may include, but are not limited to, tert-butoxyethoxyethane. These solvents can be used alone or in combination. Preferably, the inert solvent is a hydrocarbon solvent, more preferably a combination of cyclohexane and n-hexane, and even more preferably a mixture of cyclohexane and n-hexane in a mass ratio of 7-9:1.

[0058] Furthermore, as is known to those skilled in the art, trace amounts of water may be present in the inert solvent. Water is a terminator in anionic polymerization, capable of terminating chain growth reactions through proton transfer. Therefore, to ensure the smooth progress of the reaction, the present invention preferably removes water from the inert solvent. This removal can be achieved by adding a dehydrating agent to the inert solvent. The types of dehydrating agents are known to those skilled in the art, for example, 5A molecular sieve.

[0059] According to the present invention, in step 1), the first anionic polymerization conditions may include: a polymerization initiation temperature of 30-60°C, preferably 45-55°C; and a pressure of 0.1-0.3 MPa, preferably 0.1-0.2 MPa.

[0060] In step 2), the second anionic polymerization conditions may include: a polymerization initiation temperature of 30-60°C, preferably 45-55°C; and a pressure of 0.1-0.3 MPa, preferably 0.1-0.2 MPa.

[0061] In this invention, all pressures refer to gauge pressure.

[0062] According to one embodiment of the present invention, in steps 1)-2), the polymerization time can be selected based on the peak reaction temperature (peak temperature) reached in each step. The term "peak reaction temperature" or "peak temperature" refers to the highest temperature reached during the reaction process in each step. In this case, the polymerization time in step 1) can be 20-30 minutes, and the polymerization time in step 2) can be 15-30 minutes. Typically, after reaching the peak reaction temperature, the monomer conversion rate in each reaction step can reach 100% by weight.

[0063] According to the present invention, the polymerization is carried out in an atmosphere formed by an inert gas. The inert gas refers to a gas that does not chemically interact with the reactants, reaction products, and solvent under the polymerization conditions, such as nitrogen and / or Group 0 element gases (e.g., argon).

[0064] According to the present invention, an activator may be added during the anionic polymerization reaction in step (1) to effectively control the microstructure of the polymer product. The activator may be one or more of various existing substances capable of regulating the microstructure of polymers, including oxygen-containing, nitrogen-containing, sulfur-containing, and phosphorus-containing compounds. Specifically, the activator may be selected from one or more of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dioxane, crown ether, tetrahydrofurfuryl ethyl ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamine, potassium tert-butoxide, potassium tert-pentoxide, potassium lauryl alcohol, potassium alkylbenzene sulfonate, and sodium alkylbenzene sulfonate. Generally, the molar ratio of the activator to the organic monolithium initiator can be 0.2-100:1, preferably 0.5-50:1.

[0065] Generally, anionic polymerization systems do not exhibit significant termination or transfer reactions; the active sites remain even after all monomers are consumed. Therefore, the preparation method of this invention may further include contacting the resulting reaction mixture with a terminator after the polymerization reaction is complete, thereby terminating the polymerization reaction and deactivating the active sites. The terminator can be any substance commonly used in anionic polymerization that can terminate active chains, such as water and / or alcohols. The alcohol is preferably a C1-C5 alcohol, such as one or more of methanol, ethanol, n-propanol, and isopropanol. Preferably, the terminator is water.

[0066] According to the present invention, before the polymerization reaction is completed and before the terminating agent is added to terminate the reaction, the method of the present invention further includes contacting the polymerized mixture with a coupling agent to couple the active chains generated during the polymerization reaction.

[0067] The types of coupling agents are known to those skilled in the art, and may include, for example, two-arm coupling agents, three-arm coupling agents, and so on. Examples of coupling agents include one or more of methyltrichlorosilane, dimethyldichlorosilane, silicon tetrachloride, and tin tetrachloride; methyltrichlorosilane is preferred.

[0068] In a particularly preferred embodiment of the present invention, the coupling agent is a three-arm coupling agent. By using a three-arm coupling agent in combination with the antioxidant specific to the present invention, the antioxidant properties of the obtained SBS thermoplastic elastomer can be further improved. Examples of such three-arm coupling agents include one or more of methyltrichlorosilane, ethyltrichlorosilane, and methyltribromosilane.

[0069] The amount of coupling agent used is determined so that the coupled polymer can meet the specific application requirements. Generally, the organolithium initiator is calculated as lithium, and the molar ratio of the coupling agent to the organolithium initiator is preferably 0.25-0.35:1.

[0070] There are no particular limitations on the conditions under which the polymerization product is reacted with the coupling agent; any conventional conditions can be used. Generally, the polymerization product can be reacted with the coupling agent under anionic polymerization conditions.

[0071] According to the present invention, the polymer in the final mixture can be precipitated from the solution by methods such as purification precipitation, centrifugation, filtration, decantation, and hot water coagulation. Alternatively, the solvent in the reaction system can be removed by air stripping. Those skilled in the art will know this, and it will not be described in detail here.

[0072] A third aspect of the present invention provides an SBS thermoplastic elastomer prepared by the above-described preparation method.

[0073] The fourth aspect of this invention provides the application of the antioxidant of this invention in the preparation of SBS thermoplastic elastomers.

[0074] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0075] In the following examples and comparative examples, the number-average molecular weight and molecular weight distribution were determined using a gel permeation chromatography (GPC) instrument of model LC-20A purchased from Shimadzu Corporation, with THF as the mobile phase, narrow-distribution polystyrene as the standard, and the test temperature being 25°C.

[0076] In the following examples and comparative examples, the oxidation induction period (OIT, min) was measured using a DSC200PC differential scanning calorimeter manufactured by Netzsch GmbH, Germany.

[0077] In the following examples and comparative examples, the inert solvent used was a mixture of cyclohexane and n-hexane in a weight ratio of 88:12. Before polymerization, 5A molecular sieve (…) was added to the mixed solvent. Purchased from Dalian Kangyu Chemical Co., Ltd.) and stored for 1 week. Among them, the 5A molecular sieve was pre-calcined at 500℃ for 5 hours before use.

[0078] Example 1

[0079] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.10MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction, and the reaction continued for 20 minutes. Then, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which reached 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio of 0.5:1) to obtain a gel solution. The polymer had a number-average molecular weight of 61,000 and a molecular weight distribution of 1.11.

[0080] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0081] Example 2

[0082] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio of 0.6:1) to obtain a gel solution. The polymer had a number-average molecular weight of 60,000 and a molecular weight distribution of 1.12.

[0083] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0084] Example 3

[0085] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio of 0.7:1) to obtain a gel solution. The polymer had a number-average molecular weight of 61,000 and a molecular weight distribution of 1.12.

[0086] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0087] Example 4

[0088] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio of 0.8:1) to obtain a gel solution. The polymer had a number-average molecular weight of 62,000 and a molecular weight distribution of 1.10.

[0089] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0090] Example 5

[0091] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio of 0.9:1) to obtain a gel solution. The polymer had a number-average molecular weight of 59,000 and a molecular weight distribution of 1.11.

[0092] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0093] Example 6

[0094] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio 1.0:1) to obtain a gel solution. The polymer had a number-average molecular weight of 61,000 and a molecular weight distribution of 1.10.

[0095] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0096] Example 7

[0097] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.71g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was then added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2 g of water (a terminator) and 2 g of a mixture of antioxidant 1 (a compound with the structure shown in formula (I), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) and antioxidant 2 (a compound with the structure shown in formula (II), n=12, purchased from Beijing Jiyi Chemical Co., Ltd.) were added (molar ratio 1.1:1) to obtain a gel solution. The polymer had a number-average molecular weight of 59,000 and a molecular weight distribution of 1.11.

[0098] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0099] Example 8

[0100] The procedure was carried out according to Example 7, except that the amount of the mixture of antioxidant 1 and antioxidant 2 was 2.66 g, and the same adhesive solution was obtained otherwise. The polymer had a number-average molecular weight of 60,000 and a molecular weight distribution of 1.12.

[0101] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0102] Example 9

[0103] The procedure was carried out according to Example 7, except that the amount of the mixture of antioxidant 1 and antioxidant 2 was 3.33 g, and the same adhesive solution was obtained otherwise. The number average molecular weight of the polymer was 59,000, and the molecular weight distribution was 1.11.

[0104] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0105] Example 10

[0106] The procedure was carried out according to Example 7, except that the same molar amount of dimethyldichlorosilane was used instead of methyltrichlorosilane, and the same adhesive solution was obtained otherwise. The polymer had a number-average molecular weight of 59,000 and a molecular weight distribution of 1.11.

[0107] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0108] Example 11

[0109] The method of Example 7 was followed, except that antioxidant 1 was a compound with n=14 in the structure shown in Formula (I) (purchased from Beijing Jiyi Chemical Co., Ltd.), and antioxidant 2 was a compound with n=14 in the structure shown in Formula (II) (purchased from Beijing Jiyi Chemical Co., Ltd.). Otherwise, the adhesive was obtained in the same manner. The polymer had a number-average molecular weight of 61,000 and a molecular weight distribution of 1.12.

[0110] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0111] Comparative Example 1

[0112] Under high-purity nitrogen protection, 3497g of mixed solvent and 200g of styrene were added sequentially to a 10L polymerization reactor. After the reactor was deoxygenated by high-purity nitrogen purging, 0.75g of n-butyllithium was added to initiate the polymerization reaction. The polymerization initiation temperature was 50℃, and the reaction pressure was 0.1MPa. The peak temperature of 55℃ was reached after 3 minutes of reaction. After continuing the reaction for 20 minutes, 466g of butadiene was added, and the reaction pressure was 0.15MPa. The peak temperature of 85℃ was reached after 15 minutes of reaction. Five minutes after reaching the peak temperature, a sample was taken to measure the conversion rate, which was 100%. 0.50g of methyltrichlorosilane was added to the polymerization reactor to continue the coupling reaction. After the coupling reaction was completed, 0.2g of water (terminator), 2.65g of traditional antioxidant 1 (2,6-di-tert-butyl-p-cresol), and 2.65g of traditional antioxidant 2 (tris(nonylphenol) phosphite) were added to obtain the adhesive solution. The polymer has a number-average molecular weight of 60,000 and a molecular weight distribution of 1.12.

[0113] After the adhesive solution is condensed by water vapor, it is dried on a two-roll mill to obtain the SBS product. The aging test data of the product are shown in Table 1.

[0114] Table 1

[0115]

[0116] Note: The oxidation induction period test temperature was 140℃.

[0117] As shown in Table 1 above, Examples 1-11 used the antioxidant of the present invention in different proportions, with an addition amount of 0.3-0.5 parts by weight relative to 100 parts by weight of the polymer monomer; Comparative Example DS1 used a traditional antioxidant, with an addition amount of 0.8 parts by weight relative to 100 parts by weight of the polymer monomer. The data indicate that the antioxidant of the present invention has significantly better resistance to thermo-oxidative aging than traditional antioxidants.

[0118] By comparing Example 7 with Example 10, it can be seen that by using a three-arm coupling agent in combination with the antioxidant specific to this invention, the thermo-oxidative aging resistance of the obtained SBS thermoplastic elastomer can be significantly improved.

[0119] By comparing Examples 1-4 with Examples 5-7, it can be seen that when the molar ratio of the compound with the structure shown in Formula (I) to the compound with the structure shown in Formula (II) is 0.9-1.1:1, the thermo-oxidative aging resistance of the obtained SBS thermoplastic elastomer can be further significantly improved.

[0120] By comparing Example 7 with Examples 8 and 9, it can be seen that when the amount of the antioxidant is 0.4-0.5 parts by weight, the anti-thermal and oxygen aging resistance of the obtained SBS thermoplastic elastomer can be further significantly improved.

[0121] By comparing Example 7 with Example 11, it can be seen that by making antioxidant 1 a compound with n=12 in the compound structure shown in Formula (I) and antioxidant 2 a compound with n=12 in the compound structure shown in Formula (II), the thermo-oxidative aging resistance of the obtained SBS thermoplastic elastomer can be further significantly improved.

[0122] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An antioxidant, characterized in that, This antioxidant contains compounds with the structure shown in formula (I) and compounds with the structure shown in formula (II). Equation (I), Equation (II), In equations (I) and (II), n is an integer from 1 to 16. The molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.5-1.1:

1.

2. The antioxidant according to claim 1, wherein, In equations (I) and (II), n is an integer between 10 and 14.

3. The antioxidant according to claim 1, wherein, The molar ratio of the compound with the structure shown in formula (I) to the compound with the structure shown in formula (II) is 0.9-1.1:

1.

4. A method for preparing SBS thermoplastic elastomer, the method comprising the following steps: 1) Under the first anionic polymerization conditions, styrene is polymerized in an inert solvent in the presence of an organolithium initiator, and the conversion rate of styrene reaches more than 95%. 2) Under the second anionic polymerization conditions, the reaction mixture obtained in step 1) is polymerized with butadiene; 3) Under coupling reaction conditions, the polymerization product obtained in step 2) is reacted with the coupling agent; 4) Add a terminator and an antioxidant to the coupling product obtained in step 3); The antioxidant is characterized in that it is the antioxidant described in any one of claims 1-3.

5. The method according to claim 4, wherein, The amount of antioxidant used is 0.2-0.8 parts by weight relative to 100 parts by weight of polymeric monomer.

6. The method according to claim 4, wherein, The amount of antioxidant used is 0.2-0.5 parts by weight relative to 100 parts by weight of polymeric monomer.

7. The method according to claim 6, wherein, The amount of antioxidant used is 0.4-0.5 parts by weight relative to 100 parts by weight of polymeric monomer.

8. The method according to any one of claims 4-7, wherein, The first anionic polymerization conditions include: a polymerization initiation temperature of 30-60℃, a pressure of 0.1-0.3MPa, and a time of 20-30min.

9. The method according to any one of claims 4-7, wherein, The second anionic polymerization conditions include: a polymerization initiation temperature of 30-60℃, a pressure of 0.1-0.3MPa, and a time of 15-30min.

10. The method according to any one of claims 4-7, wherein, The organolithium initiator is a compound represented by formula (Ⅲ). R3Li type (Ⅲ). In formula (Ⅲ), R3 is a C1-C6 alkyl group, C3 ... 12 cycloalkyl, C7-C 14 Aryl or C6-C 12 Aryl groups.

11. The method according to any one of claims 4-7, wherein, The coupling agent is a three-arm coupling agent.

12. The method according to claim 11, wherein, The coupling agent is methyltrichlorosilane.

13. The method according to any one of claims 4-7, wherein, The organolithium initiator is calculated based on lithium, and the molar ratio of the coupling agent to the organolithium initiator is 0.25-0.35:

1.

14. An SBS thermoplastic elastomer, characterized in that, The SBS thermoplastic elastomer is prepared by the method described in any one of claims 4-13.

15. The use of the antioxidant according to any one of claims 1-3 in the preparation of SBS thermoplastic elastomer.

Images