CN108017869B

CN108017869B - Polymer composition and method for improving aging resistance of styrene thermoplastic elastomer

Info

Publication number: CN108017869B
Application number: CN201610934827.9A
Authority: CN
Inventors: 康新贺; 徐林; 王雪; 王妮妮; 刘辉; 孙文娟
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2016-11-01
Filing date: 2016-11-01
Publication date: 2021-02-05
Anticipated expiration: 2036-11-01
Also published as: CN108017869A

Abstract

The invention discloses a polymer composition and a method for improving the aging resistance of a styrene thermoplastic elastomer, wherein the polymer composition and the method adopt a compound shown in formula I as an aging inhibitor, and can effectively improve the aging resistance of monovinylarene-conjugated diene copolymer, especially the styrene thermoplastic elastomer (such as SBS), and prolong the storage life and service life of the monovinylarene-conjugated diene copolymer, especially the styrene thermoplastic elastomer, even if other aging resistant substances are not added.

Description

Polymer composition and method for improving aging resistance of styrene thermoplastic elastomer

Technical Field

The invention relates to a polymer composition and a method for improving the aging resistance of a styrene thermoplastic elastomer.

Background

Styrene-based thermoplastic elastomers (also called styrene Block Copolymers, SBCs for short) are the thermoplastic elastomers with the highest worldwide production and the most similar rubber performance. SBS styrene thermoplastic elastomer is a variety of SBCs with the highest yield (70% or more), the lowest cost, and a wide range of applications, and is a triblock copolymer obtained by polymerizing styrene and butadiene as monomers, and is called "third-generation synthetic rubber" because it has characteristics of both plastics and rubber. Similar to styrene butadiene rubber, SBS can contact with water, weak acid, alkali and the like, has the characteristics of excellent tensile strength, large surface friction coefficient, good low-temperature performance, excellent electrical performance, good processability and the like, and becomes the thermoplastic elastomer with the largest consumption at present.

At present, SBS is mainly used in four application fields of rubber products, resin modifiers, adhesives and asphalt modifiers. In the aspect of rubber products, SBS molded products are mainly used in the shoe (sole) making industry, and extruded products are mainly used for rubber tubes and adhesive tapes; as a resin modifier, a small amount of SBS is respectively blended with polypropylene (PP), Polyethylene (PE) and Polystyrene (PS), so that the low-temperature performance and the impact strength of the product can be obviously improved; SBS as adhesive has high solid matter content, fast drying and low temperature resistance; the SBS serving as a modifier of the building asphalt and the road asphalt can obviously improve the weather resistance and the load resistance of the asphalt.

Although SBS has many advantages in performance, double bonds in the soft polybutadiene block part of SBS elastomer are active chemically, and have poor aging resistance to oxygen, ozone, heat, light and the like, so that SBS has aging phenomena of gradually sticking, hardening and embrittling or cracking in the storage process, and SBS and its product performance gradually decrease along with the aging process, so that the SBS and its product completely lose use value.

Therefore, it is desirable to add certain chemicals to SBS and products thereof to improve their resistance to the above-mentioned destructive effects and to retard or inhibit the aging process, thereby extending the shelf life and useful life of SBS and products thereof.

For example, CN101575423A discloses a rubber antioxidant comprising a rare earth substance formed by the reaction of one or more Re-containing oxides, one or more M-containing oxides, one or more organic acids and/or organic acid derivatives having a carbon chain length of C4 to C22, and one or more alcohols and/or alcohol derivatives having a carbon chain length of C4 to C22, wherein Re is a light rare earth element, and M is a metal element other than a rare earth element. However, the use of such a rare earth rubber antioxidant introduces metal elements into the final product, which makes it difficult to satisfy the practical use requirements of SBS, and the anti-aging performance of the antioxidant needs to be further improved.

In view of the above, it is highly desirable to develop an antioxidant suitable for a styrenic thermoplastic elastomer, particularly an SBS type thermoplastic elastomer.

Disclosure of Invention

The invention aims to provide a polymer composition containing a monovinylarene-conjugated diene copolymer, and the anti-aging agent contained in the polymer composition can obviously improve the anti-aging performance of the monovinylarene-conjugated diene copolymer.

According to a first aspect of the present invention, there is provided a polymer composition comprising a monovinylarene-conjugated diene copolymer comprising structural units derived from a monovinylarene and structural units derived from a conjugated diene, and at least one antioxidant, wherein the antioxidant is selected from compounds of formula I,

in the formula I, R₁And R₂Each independently is C₁-C₃Alkyl of R₃Is C₁-C₆Alkyl group of (1).

According to a second aspect of the present invention, there is provided a method for improving aging resistance of a styrene-based thermoplastic elastomer, comprising adding a compound represented by formula I to the styrene-based thermoplastic elastomer,

in the formula I, R₁And R₂Each independently is C₁-C₃The alkyl group of (a) is,R₃is C₁-C₆Alkyl group of (1).

The compound shown in the formula I is used as the anti-aging agent of the monovinylarene-conjugated diene copolymer, particularly the styrene thermoplastic elastomer (such as SBS), so that the anti-aging performance of the monovinylarene-conjugated diene copolymer, particularly the styrene thermoplastic elastomer can be effectively improved even if other anti-aging substances are not added, and the storage life and the service life of the monovinylarene-conjugated diene copolymer, particularly the styrene thermoplastic elastomer (such as SBS) are prolonged.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

According to a first aspect of the present invention, there is provided a polymer composition comprising a monovinylarene-conjugated diene copolymer and at least one antioxidant.

The anti-aging agent is selected from a compound shown as a formula I,

in the formula I, R₁And R₂Each independently is C₁-C₃The alkyl group of (b) may be, for example, a methyl group, an ethyl group or a propyl group (including various isomers of a propyl group, such as n-propyl group and isopropyl group). Preferably, in formula I, R₁And R₂Each independently being methyl or ethyl. More preferably, in formula I, R₁And R₂Are all methyl.

In the formula I, R₃Is C₁-C₆The alkyl group of (b) may be, for example, a methyl group, an ethyl group, a propyl group (including various isomers of propyl groups such as n-propyl group and isopropyl group), a butyl group (including various isomers of butyl groups such as n-butyl group, sec-butyl group, isobutyl group and tert-butyl group), a pentyl group (including various isomers of pentyl groups such as n-pentyl group, isopentyl group, tert-pentyl group and neopentyl group), or a hexyl group (including various isomers of hexyl groups such as n-hexyl group). Preferably, in formula I, R₃Is methyl, ethyl, n-propyl, or isopropyl. More preferably, in formula I, R₃Is n-propyl or isopropyl.

In a preferred embodiment, in formula I, R₁And R₂Is methyl, R₃Is n-propyl or isopropyl.

According to the polymer composition of the present invention, the amount of the antioxidant may be conventionally selected. The anti-aging agent used in the polymer composition according to the present invention has high anti-aging performance, and can effectively improve the anti-aging performance of the monovinylarene-conjugated diene copolymer even at a relatively low dosage. The polymer composition according to the present invention, the content of the antioxidant is preferably 0.1 to 1 part by weight, more preferably 0.3 to 0.8 part by weight, relative to 100 parts by weight of the monovinylarene-conjugated diene copolymer.

According to the polymer composition of the present invention, the monovinylarene-conjugated diene copolymer contains structural units derived from a monovinylarene and structural units derived from a conjugated diene. In the present invention, "structural unit derived from xxx" means that the structural unit is a structural unit formed by addition polymerization of the monomer, for example: the structural unit derived from a monovinylarene refers to a structural unit formed by addition polymerization of a monovinylarene.

The monovinylarene refers to a compound formed by substituting one hydrogen on an aromatic ring with a vinyl group, such as: the monovinylarene can be one or more than two compounds selected from the compounds shown in the formula II,

in the formula II, R₄Is C₆-C₂₀Specific examples thereof may include, but are not limited to: phenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, o-tert-butylphenyl, m-tert-butylphenyl, p-dodecylphenyl, 2, 4-di-n-butylphenyl, n-propylphenyl and 2, 4-diethylphenyl.

Preferably, the monovinyl aromatic hydrocarbon is one or more selected from the group consisting of styrene, 2-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3, 5-diethylstyrene, 3, 5-di-n-butylstyrene, 4-n-propylstyrene and 4-dodecylstyrene.

More preferably, the monovinylarene is one or more selected from styrene, 2-methylstyrene and 4-methylstyrene.

Further preferably, the monovinylarene is styrene.

The conjugated diene is an unsaturated chain hydrocarbon having a conjugated double bond (i.e., -C-) in its molecular structure, and may be any of various conjugated dienes commonly used in the art, and is not particularly limited. For example: the conjugated diene may be selected from C₄-C₈One or more than two of the conjugated diolefins (2).

Preferably, the conjugated diene is one or more selected from butadiene, isoprene, 1, 3-pentadiene, 1, 3-hexadiene and 2, 3-dimethylbutadiene.

More preferably, the conjugated diene is butadiene and/or isoprene.

Further preferably, the conjugated diene is butadiene.

The microstructure of the monovinylarene-conjugated diene copolymer can be selected according to the particular application of the polymer composition.

Generally, the content of structural units derived from monovinylarene may range from 15 to 45 wt%, preferably from 16 to 40 wt%, based on the total amount of the monovinylarene-conjugated diene copolymer; the content of structural units derived from conjugated diolefin may be from 55 to 85% by weight, preferably from 60 to 74% by weight. In the invention, the type and content of the structural unit in the monovinylarene-conjugated diene copolymer are determined by a nuclear magnetic resonance hydrogen spectrometry.

The content of the structural units derived from a conjugated diene containing a vinyl group as a side group in the monovinylarene-conjugated diene copolymer may be 5 to 75% by weight, preferably 10 to 72% by weight, more preferably 13 to 70% by weight, based on the total amount of the structural units derived from a conjugated diene. The structural units derived from conjugated diolefins which contain vinyl groups as side groups are generally structural units formed by 1, 2-polymerization and/or 3, 4-polymerization of the conjugated diolefins. In the present invention, the content of the structural unit containing a vinyl group as a side group is measured by a nuclear magnetic resonance hydrogen spectrometry.

According to the polymer composition of the present invention, the monovinylarene-conjugated diene copolymer may be a random copolymer or a block copolymer.

According to the polymer composition of the present invention, the monovinylarene-conjugated diene copolymer may be a linear copolymer, a coupled polymer, or a combination of a linear copolymer and a coupled polymer. The coupled polymer may be obtained by coupling a linear copolymer with a coupling agent. That is, the monovinylarene-conjugated diene copolymer is a monovinylarene-conjugated diene coupled polymer and/or a monovinylarene-conjugated diene linear copolymer, and the coupled polymer is formed by coupling the monovinylarene-conjugated diene linear copolymer with a coupling agent.

The coupling agent can be various common substances capable of coupling molecular chains of the linear monovinylarene-conjugated diene copolymer to form a coupled polymer, such as one or more than two of halides, ethers, aldehydes, ketones and esters.

Specific examples of the coupling agent may include, but are not limited to: dimethyl dichlorosilane, methyl trichlorosilane, tetravinylsilane, tetrachloromethane, silicon tetrachloride, stannic chloride, dimethyl terephthalate, epichlorohydrin and one or more compounds selected from the compounds shown in formula III,

in formula III, n is an integer of 1 to 12, and may be, for example, 1,2, 3,4, 5, 6, 7, 8, 9, 10, 11 or 12. Preferably, in formula III, n is an integer from 3 to 10. More preferably, in formula III, n is an integer from 7 to 10.

In the formula III, R₅And R₆Identical or different, each independently is C₁-C₃Such as methyl, ethyl, n-propyl or isopropyl. Preferably, R₅And R₆Are the same.

Specifically, the compound represented by formula III may be one compound or two or more compounds selected from dimethyl malonate, diethyl malonate, dipropyl malonate, dimethyl succinate, diethyl succinate, dipropyl succinate, dimethyl glutarate, diethyl glutarate, dipropyl glutarate, dimethyl adipate, diethyl adipate, dipropyl adipate, dimethyl pimelate, diethyl pimelate, dipropyl pimelate, dimethyl suberate, diethyl suberate, dipropyl suberate, dimethyl azelate, diethyl azelate, dipropyl azelate, dimethyl sebacate, diethyl sebacate, and dipropyl sebacate.

Preferably, the coupling agent is one or more than two of dimethyldichlorosilane, methyltrichlorosilane, epichlorohydrin and a compound shown in formula III. More preferably, the coupling agent is epichlorohydrin and/or a compound represented by formula III.

The content of the coupled polymer in the present invention is not particularly limited and may be conventionally selected. Generally, the content of the coupled polymer may be 60 to 100% by weight, preferably 65 to 90% by weight, based on the total amount of the monovinylarene-conjugated diene copolymer, and the content of the monovinylarene-conjugated diene linear copolymer may be 0 to 40% by weight, preferably 10 to 35% by weight.

The molecular weight of the linear monovinylarene-conjugated diene copolymer may be selected according to the particular application of the polymer composition. Generally, the linear monovinylarene-conjugated diene copolymer may have a number average molecular weight of from 4 to 20, preferably from 5 to 18, more preferably from 5.5 to 16, ten thousand and a molecular weight distribution index of from 1.01 to 1.8, more preferably from 1.01 to 1.6.

In the present invention, the molecular weight, the distribution thereof, and the coupling efficiency were measured by gel permeation chromatography, specifically by ALLIANCE2690 type Gel Permeation Chromatograph (GPC) available from WATERS, USA, wherein the gel permeation chromatograph was equipped with a differential detector, Tetrahydrofuran (THF) was used as a mobile phase, the column temperature was 25 ℃, and narrow-distribution polystyrene was used as a standard sample. In the present invention, the molecular weight and distribution of the linear copolymer can be measured before or after the coupling step.

The monovinylarene-conjugated diene copolymer can be prepared by conventional methods, for example, by anionic polymerization.

According to the polymer composition of the first aspect of the present invention, good aging resistance can be exhibited even if a substance capable of improving the aging resistance of the monovinylarene-conjugated diene copolymer is not contained in addition to the compound represented by formula I.

According to a second aspect of the present invention, there is provided a method for improving aging resistance of a styrenic thermoplastic elastomer, which comprises adding a compound represented by formula I to a styrenic thermoplastic elastomer,

The compounds of formula I have been described in detail in the polymer composition according to the first aspect of the invention and will not be described in detail here.

According to the method of the second aspect of the present invention, the styrene-based thermoplastic elastomer may be various types of common thermoplastic elastomers, such as thermoplastic elastomers formed from styrene and conjugated diene, and specific examples thereof may include, but are not limited to, styrene-butadiene-styrene-based thermoplastic elastomers and partial hydrides thereof, and styrene-isoprene-styrene-based thermoplastic elastomers and partial hydrides thereof. Preferably, the styrene-based thermoplastic elastomer is a styrene-butadiene-styrene-based thermoplastic elastomer. More preferably, the styrene-based thermoplastic elastomer is a styrene-butadiene-styrene-based thermoplastic elastomer synthesized by a coupling method.

The styrenic thermoplastic elastomer can be prepared by a conventional method, for example: the styrenic thermoplastic elastomer can be prepared by a three-stage polymerization method.

In a preferred embodiment of the present invention, the styrene-based thermoplastic elastomer is a styrene-butadiene-styrene-type thermoplastic elastomer, and the content of structural units derived from styrene may be 15 to 45% by weight, preferably 25 to 40% by weight, more preferably 30 to 35% by weight, based on the total amount of the styrene-butadiene-styrene-type thermoplastic elastomer; the content of structural units derived from butadiene may be 55 to 85% by weight, preferably 60 to 75% by weight, more preferably 65 to 70% by weight.

In this preferred embodiment, the styrene-butadiene-styrene type thermoplastic elastomer contains the structural unit derived from butadiene as a vinyl group as a side group in an amount of preferably 5 to 25% by weight, more preferably 10 to 20% by weight, and further preferably 13 to 18% by weight, based on the total amount of the structural units derived from butadiene.

In this preferred embodiment, the styrene-butadiene-styrene type thermoplastic elastomer preferably contains a coupled polymer formed by coupling a styrene-butadiene-styrene linear copolymer with a coupling agent, and optionally a styrene-butadiene-styrene linear copolymer.

The coupling agent may be any of various conventional substances capable of coupling molecular chains of a styrene-butadiene-styrene linear copolymer together to form a coupled polymer, such as one or more of halides, ethers, aldehydes, ketones, and esters.

In the formula III, R₅And R₆Identical or different, each independently is C₁-C₃Such as methyl, ethyl, n-propyl, or isopropyl. Preferably, R₅And R₆Are the same.

The content of the coupled polymer may be 60 to 100% by weight, preferably 65 to 90% by weight, more preferably 70 to 85% by weight, and still more preferably 76 to 82% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer, and the content of the styrene-butadiene-styrene linear copolymer may be 0 to 40% by weight, preferably 10 to 35% by weight, more preferably 15 to 30% by weight, and still more preferably 18 to 24% by weight.

In this preferred embodiment, the number average molecular weight of the styrene-butadiene-styrene linear copolymer may be 4 to 10 ten thousand, preferably 5 to 9 ten thousand, and more preferably 5.5 to 8 ten thousand. Molecular weight distribution index (M) of the styrene-butadiene-styrene linear copolymer_w/M_n) It may be 1.5 or less, preferably 1.01 to 1.3, more preferably 1.01 to 1.2, and still more preferably 1.01 to 1.1.

The styrene-butadiene-styrene type thermoplastic elastomer according to this preferred embodiment can be prepared by a method comprising the steps of:

(1) polymerizing styrene in a solvent under anionic polymerization conditions in the presence of an organolithium initiator to an extent such that the conversion of styrene is 99% or more;

(2) adding butadiene to the mixture obtained in step (1) and carrying out polymerization under anionic polymerization conditions to the extent that the conversion of butadiene is 99% or more;

optionally, (3) reacting the mixture obtained in the step (2) with a coupling agent under the coupling reaction condition;

(4) adding the anti-aging agent according to the present invention to the mixture obtained in step (2) or the mixture obtained in step (3).

In the present invention, "optional" means "containing or not containing", "including or not including".

In the step (1), the organolithium initiator may be any of various organomonolithium compounds, organodilithium compounds or organopolylithium compounds capable of initiating polymerization of monovinylarene and conjugated diene, which are commonly used in the field of anionic polymerization, and is not particularly limited. The organolithium initiator is preferably an organomonolithium compound, more preferably a compound represented by formula II,

R₇li (formula IV)

In the formula IV, R₇Is C₁-C₆Alkyl of (C)₃-C₁₂Cycloalkyl of, C₇-C₁₄Aralkyl or C₆-C₁₂Aryl group of (1).

Said C is₁-C₆Alkyl of (2) includes C₁-C₆Straight chain alkyl of (2) and C₃-C₆Specific examples thereof 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.

Said C is₃-C₁₂Specific examples of the cycloalkyl group of (a) may include, but are not limited to: cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-n-propylcyclohexyl and 4-n-butylcyclohexyl.

Said C is₇-C₁₄Specific examples of the aralkyl group of (a) may include, but are not limited to: phenylmethyl, phenylethyl, phenyl-n-propyl, phenyl-n-butyl, phenyl-t-butyl, phenyl-isopropyl, phenyl-n-pentyl and phenyl-n-butyl.

Said C is₆-C₁₂Specific examples of the aryl group of (a) may include, but are not limited to: phenyl, naphthyl, 4-methylphenyl and 4-ethylphenyl.

Specific examples of the organolithium initiator may include, but are not limited to: one or more of ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, 2-naphthyllithium, 4-butylphenyl lithium, 4-tolyllithium, cyclohexyllithium, and 4-butylcyclohexyllithium.

Preferably, the organolithium initiator is n-butyllithium and/or sec-butyllithium. More preferably, the organolithium initiator is n-butyllithium.

The amount of the organolithium initiator to be used may be selected according to the molecular weight of the intended styrene-butadiene-styrene linear copolymer, and is not particularly limited. Methods for determining the amount of initiator to be used in view of the desired molecular weight of the polymer are well known to those skilled in the art and will not be described in detail herein.

In the step (1), the kind of the solvent is not particularly limited, and may be a solvent commonly used in solution polymerization, as long as the solvent is in a liquid state under the polymerization reaction conditions, does not participate in the polymerization reaction, and does not react with the polymer obtained by the reaction. Preferably, the solvent may be one or two or more of cycloalkane, aromatic hydrocarbon and isoparaffin. Specifically, the solvent may be one or more of benzene, toluene, hexane, cyclohexane, pentane, and heptane. The amount of the solvent may be conventionally selected. Generally, the solvent is used in an amount such that the concentration of the monomers (i.e., styrene and butadiene) is from 8 to 20 weight percent, preferably from 12 to 18 weight percent.

In steps (1) and (2), the anionic polymerization conditions may be conventional conditions sufficient for anionic polymerization to occur. Specifically, the initiation temperature of the polymerization reaction may be 30 to 80 ℃, preferably 35 to 70 ℃, more preferably 40 to 60 ℃, and still more preferably 40 to 50 ℃. The polymerization can be carried out under conventional pressure. Generally, the polymerization may be carried out at a pressure of 0.005 to 1.5MPa, preferably 0.1 to 0.3MPa, in terms of gauge pressure. The heat of reaction may or may not be removed during the polymerization reaction. When the heat of reaction is removed, the polymerization temperature may be controlled to 40 to 110 ℃ and preferably 50 to 100 ℃. The coupling reaction can be carried out at the same temperature as the polymerization reaction, and can be carried out generally at a temperature of 40 to 110 ℃ and preferably at a temperature of 50 to 100 ℃. The duration of the coupling reaction is such that the desired coupling efficiency can be obtained. In general, the duration of the coupling reaction may be from 0.1 to 0.5 hours.

In the step (3), the coupling reaction may be carried out under conventional conditions after the coupling agent is added. In general, after the coupling agent is added, the coupling reaction can be carried out under ordinary conditions as long as the coupling reaction is ensured to proceed smoothly. Generally, the coupling reaction can be carried out under the same conditions as the polymerization reaction, for example, at a temperature of 50 to 120 ℃, preferably 60 to 90 ℃, more preferably 65 to 85 ℃. The time of the coupling reaction is determined to enable the coupling efficiency to meet the requirement.

In the step (3), the amount of the coupling agent may be selected according to the desired coupling efficiency, and is not particularly limited. Methods for determining the amount of coupling agent to be used, based on the desired coupling efficiency, are well known to those skilled in the art and will not be described in detail herein.

After the polymerization reaction (coupling reaction in the presence of coupling reaction) is completed, the resulting reaction mixture may be contacted with a terminating agent to inactivate the active centers. The terminating agent may be any of the various substances capable of terminating a living chain commonly used in the field of anionic polymerization, and may be, for example, water and/or an alcohol, preferably C₁-C₅Such as one or more of methanol, ethanol, n-propanol, and isopropanol. Preferably, the terminator may be isopropyl alcohol. The amount of the terminator to be used is not particularly limited so long as it can inactivate the active species.

In step (4), the antioxidant according to the present invention may be mixed with the polymer obtained in step (2) or the mixture obtained in step (3) using a conventional method.

After the polymerization reaction (including the coupling reaction, which is a coupling reaction) is completed, a step of removing the solvent may be further included. The step of removing the solvent may be performed before the addition of the antioxidant, or may be performed after the addition of the antioxidant, and is preferably performed after the addition of the antioxidant. The solvent may be extracted using conventional methods, for example: alcoholization precipitation, centrifugation, filtration decantation, hot water coagulation and steam stripping.

According to the method of the second aspect of the present invention, the amount of the compound represented by formula I may be selected according to the kind of the styrenic thermoplastic elastomer. In general, the compound represented by formula I may be added in an amount of 0.1 to 1 part by weight, preferably 0.3 to 0.8 part by weight, based on 100 parts by weight of the styrene-based thermoplastic elastomer.

According to the method of the second aspect of the invention, the aging resistance of the styrene thermoplastic elastomer can be remarkably improved by singly using the compound shown in the formula I. That is, the method according to the second aspect of the present invention may not additionally add a substance capable of improving the aging resistance of a styrenic thermoplastic elastomer other than the compound represented by formula I. That is, according to the method of the second aspect of the present invention, the antioxidant is selected from the compounds represented by formula I.

The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.

In the following examples and comparative examples, the following test methods are referred to.

(1) The microstructure of the copolymer is obtained by measuring the prepared polymer composition by adopting an AVANCE DRX 400MHz nuclear magnetic resonance spectrometer of Bruker company of Switzerland, and the solvent is deuterated chloroform; wherein "St%" represents the content of a structural unit derived from styrene, St non-block% represents the content of a styrene structural unit present in a non-block form in the copolymer, St block% represents the content of a styrene block in the copolymer, the styrene block means a segment in which a structural unit is formed of styrene and the number of the structural unit is more than 5, "1, 4-Bd%" represents the content of a structural unit in which butadiene is 1, 4-polymerized, and "1, 2-Bd%" represents the content of a structural unit in which butadiene is 1, 2-polymerized.

(2) Molecular weight, molecular weight distribution index (M)_w/M_n) And the coupling efficiency was determined by measuring the polymer composition prepared by means of a Gel Permeation Chromatograph (GPC) equipped with a differential detector and flowing with tetrahydrofuran, model ALLIANCE2690, WATERSThe column temperature was 25 ℃ and narrow distribution polystyrene was used as a standard.

(3) The oxidation induction period (OIT) is measured by adopting an MDSC2910 Differential Scanning Calorimetry (DSC) instrument of the American TA company, the temperature rise rate is 10 ℃/min, the test temperature is 185 ℃ in an oxygen atmosphere, and the longer the oxidation induction period is, the better the anti-aging performance is.

(4) The aging test method is a hot air aging method, and the specific operation method comprises the following steps:

the samples were placed in an aging oven (model CLM-QLH-100, Touchfang Vanda) at a temperature of 70 ℃ for 72 hours, and the tensile strength and elongation at break before and after hot air aging were measured. The greater the change in tensile strength and elongation at break before and after hot air aging, measured according to the methods specified in GB/T528-2009, the poorer the aging resistance of the sample.

(5) The mechanical properties were measured by the method specified in GB/T528-2009 using Shimadzu AG-20KNG tensile machine, and the samples used were type I samples.

(6) In examples 1 to 9, the samples for measuring the tensile strength and the elongation at break before and after hot air aging were measured by directly sampling the dried SBS thermoplastic elastomer;

in examples 10 to 21, the samples for determining the mechanical properties were prepared by vulcanizing the polymer compositions prepared according to the A series of formulations of GB/T8656-1998, under vulcanization conditions comprising: mixing raw rubber by using an open mill, and mixing at the roll temperature of 50 +/-5 ℃; the vulcanization temperature is 145 ℃, the pressure is more than 10MPa, and the vulcanization time is 35 minutes.

Examples 1-21 are intended to illustrate the invention.

Example 1

Under the protection of high-purity nitrogen, 2288g of mixed solvent (cyclohexane and N-hexane in a weight ratio of 88: 12) and 131g of styrene are sequentially added into a 5-liter polymerization kettle, and a polymerization system passes through high-purity N₂After the displacement deoxidation, 6.88mmol of n-butyllithium was added to conduct polymerization. The polymerization initiation temperature was 42 ℃ and the reaction pressure was 0.1 MPa. The reaction is continued when the peak temperature is 57 ℃ after 20 minutesAfter 5 minutes (detection shows that the conversion rate of the styrene is more than 99 percent), 305g of butadiene is added, the reaction is carried out for 20 minutes until the peak temperature is 98 ℃, and after 10 minutes (detection shows that the conversion rate of the butadiene is 100 percent), 4.128mmol (0.382g) of epichlorohydrin is added into the polymerization kettle, and the coupling reaction is carried out for 20 minutes. After the coupling reaction was completed, 0.2g of isopropanol as a terminator and 1.308g of 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) as an antioxidant were added

Wherein R is₁And R₂Is methyl, R₃N-propyl, available from carbofuran technologies ltd), and stirred well. The obtained glue solution is condensed by water vapor and dried by an open mill to obtain the SBS thermoplastic elastomer, the molecular structure parameters of the SBS thermoplastic elastomer are listed in the table 1, and the physical and mechanical properties and the aging experimental data of the prepared SBS thermoplastic elastomer are listed in the table 2.

Example 2

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 4, 4' -butylidenebis (6-t-butyl-3-methylphenol) was used in an amount of 2.180g as an anti-aging agent.

Example 3

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) was used in an amount of 2.616g as an anti-aging agent.

Example 4

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) was used in an amount of 3.488g as an anti-aging agent.

Example 5

An SBS thermoplastic elastomer was prepared in the same manner as in example 1 except that 4, 4' -butylidenebis (6-t-butyl-3-methylphenol) was used in an amount of 0.436g as an anti-aging agent.

Example 6

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) was used in an amount of 4.360g as an anti-aging agent.

Comparative example 1

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 2, 6-di-t-butyl-p-phenol (abbreviated as 264) was used as an antioxidant.

Comparative example 2

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate (1076 for short) was used as an antioxidant.

Comparative example 3

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that a mixture of 264 and 1076 (264: 1076: 1: 2 by weight) was used as an antioxidant.

Comparative example 4

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that a mixture of 264 and trinonylphenyl phosphite (TNPP for short) (264: TNPP is 1: 1 by weight) was used as an antioxidant.

Comparative example 5

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 4, 6-bis (octylthiomethyl) o-cresol (1520 for short) was used as an antioxidant.

Comparative example 6

An SBS thermoplastic elastomer was prepared in the same manner as in example 1 except that 4, 4' -methylenebis (6-tert-butyl-3-methylphenol) (abbreviated as 702) was used as an antioxidant.

Comparative example 7

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that the antioxidant was a mixture of 1076 and 1520 (1076: 1520: 1 by weight ratio) as an antioxidant.

Comparative example 8

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that the antioxidant was dilauryl dithiodipropionate (DLPT for short) as the antioxidant.

Comparative example 9

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that a mixture of DLPT and 1076 (DLPT: 1076: 1 by weight) was used as an antioxidant.

Comparative example 10

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that TNPP was used as an anti-aging agent.

Comparative example 11

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that tris [2, 4-di-t-butylphenyl ] phosphite (168 for short) was used as an antioxidant.

Comparative example 12

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that a mixture of 1520 and 168 (1520: 168: 1: 2 by weight) was used as an anti-aging agent.

Comparative example 13

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid (abbreviated as 3114) was used as an antioxidant.

Comparative example 14

An SBS thermoplastic elastomer was prepared in the same manner as in example 1, except that a mixture of 3114 and 168 (3114: 168: 1: 2 by weight) was used as an antioxidant.

Example 7

Under the protection of high-purity nitrogen, 2288g of mixed solvent (cyclohexane and N-hexane in a weight ratio of 88: 12) and 153g of styrene are sequentially added into a 5-liter polymerization kettle, and a polymerization system passes through high-purity N₂After the displacement deoxidation, 6.48mmol of n-butyllithium was added to conduct polymerization. The polymerization initiation temperature was 41 ℃ and the reaction pressure was 0.12 MPa. After the reaction reaches the peak temperature of 59 ℃ in 23 minutes and is continued for 5 minutes (the conversion rate of styrene is more than 99 percent in the detection), 283g of butadiene is added, and after the reaction reaches the peak temperature of 95 ℃ in 22 minutes and the peak temperature of 10 minutes (the conversion rate of butadiene is 100 percent in the detection), 3.89mmol (0.36g) of chloropropylene oxide is added into a polymerization kettleAlkane, and the coupling reaction is continued for 20 min. After the coupling reaction was completed, 0.2g of isopropanol as a terminator and 1.308g of 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) as an antioxidant were added and stirred uniformly. The obtained glue solution is condensed by water vapor and dried by an open mill to obtain the SBS thermoplastic elastomer, the molecular structure parameters of the SBS thermoplastic elastomer are listed in the table 1, and the physical and mechanical properties and the aging experimental data of the prepared SBS thermoplastic elastomer are listed in the table 2.

Example 8

Under the protection of high-purity nitrogen, 2288g of mixed solvent (cyclohexane and N-hexane in a weight ratio of 88: 12) and 142g of styrene are sequentially added into a 5-liter polymerization kettle, and a polymerization system passes through high-purity N₂After the displacement deoxidation, 6.22mmol of n-butyllithium was added to conduct polymerization. The polymerization initiation temperature was 40 ℃ and the reaction pressure was 0.14 MPa. After the reaction reaches 60 ℃ at the peak temperature after 25 minutes, the reaction is continued for 5 minutes (the conversion rate of styrene is more than 99 percent at the moment by detection), 294g of butadiene is added, after the reaction reaches 98 ℃ at the peak temperature after 20 minutes, the peak temperature is 10 minutes (the conversion rate of butadiene is 100 percent at the moment by detection), 1.4306mmol (0.349g) of dipropyl pimelate is added into the polymerization kettle, and the coupling reaction is continued for 20 minutes. After the coupling reaction was completed, 0.2g of isopropanol as a terminator and 1.308g of 4, 4' -ethylenebis (6-t-butyl-3-methylphenol) as an antioxidant were added

Wherein R is₁And R₂Is methyl, R₃Methyl, available from carbofuran technologies ltd), and stirred well. The obtained glue solution is condensed by water vapor and dried by an open mill to obtain the SBS thermoplastic elastomer, the molecular structure parameters of the SBS thermoplastic elastomer are listed in the table 1, and the physical and mechanical properties and the aging experimental data of the prepared SBS thermoplastic elastomer are listed in the table 2.

Example 9

An SBS thermoplastic elastomer was prepared in the same manner as in example 8, except that the coupling reaction was not performed after the polymerization reaction was completed, but the antioxidant was directly added. The obtained glue solution is condensed by water vapor and dried by an open mill to obtain the SBS thermoplastic elastomer, the molecular structure parameters of the SBS thermoplastic elastomer are listed in the table 1, and the physical and mechanical properties and the aging experimental data of the prepared SBS thermoplastic elastomer are listed in the table 2.

TABLE 1

Item	Example 1	Example 7	Example 8
				Number average molecular weight¹All of	6.34	6.73	7.01
Molecular weight distribution index¹	1.05	1.05	1.06
				Coupling efficiency,% of	79.51	78.32	78.92
St％，wt％	30.2	35.1	32.5
				1,2-Bd％，wt％	14.5	17.9	16.8
1,4-Bd％，wt％	85.5	82.1	83.2

¹: molecular weight of uncoupled Polymer determined after coupling reaction and distribution thereof

TABLE 2

TABLE 3

The results of tables 2 and 3 confirm that the aging resistance of the SBS thermoplastic elastomer can be effectively improved by the method of the present invention even if only one anti-aging agent is used, thereby effectively extending the pot life and service life of the SBS thermoplastic elastomer.

Example 10

2288g of a mixed solvent (a mixed solution of cyclohexane and n-hexane, wherein the mass ratio of cyclohexane/n-hexane is 88/12), 78g of Styrene (ST) and 234g of butadiene (1,3-BD) were charged in a 5-liter stainless steel stirred tank reactor under the protection of high-purity nitrogen gas. Using 0.78g of 2, 2-bis (tetrahydrofuryl) propane (DTHFP) as a polarity regulator, killing impurities by using n-butyllithium, and then adding 2.08mmol of n-butyllithium as an initiator to perform polymerization reaction, wherein the initiation temperature is 50 ℃, the polymerization pressure is 0.10MPa, and heat is not removed in the reaction process. The temperature of the reaction solution in the reaction vessel reached a peak temperature of 73.3 ℃ at the time of 5 minutes of the reaction, and the polymerization pressure was 0.22MPa at this time. After the temperature reached the peak temperature for 1 minute (i.e., from the time when the temperature reached the peak temperature, at the time of 1 minute), 0.3744mmol of Diethyl Pimelate (DP) was added to the reaction vessel for coupling, and after stirring for 30 minutes, 0.516mmol of isopropyl alcohol was added to terminate the reaction. Finally, 1.2480g of 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) as an antioxidant was added thereto and stirred uniformly. The obtained glue solution is subjected to water vapor condensation to obtain the polymer composition according to the invention, wherein the molecular structure parameters of the monovinylarene-conjugated diene copolymer in the polymer composition, the physical and mechanical properties of the polymer composition, the dynamic mechanical properties and the aging experimental data are listed in table 4.

Example 11

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that diethyl pimelate was added to the reactor after the temperature in the reactor reached the peak temperature for 5 minutes.

Example 12

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that diethyl pimelate was added to the reaction vessel after the temperature in the reaction vessel reached the peak temperature for 7 minutes.

Example 13

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that the coupling agent was tin tetrachloride.

Example 14

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that the coupling agent was silicon tetrachloride.

Example 15

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that the polarity modifier was tetrahydrofurfuryl ethyl ether (ETE).

Example 16

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that the polarity modifier was diethylene glycol dimethyl ether (2G).

Example 17

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that the polarity modifier was Tetramethylethylenediamine (TMEDA).

Comparative example 15

Monovinylarene-conjugated diene copolymer and polymer compositions were prepared in the same manner as in example 10, except that 1076 was used as an antioxidant.

Comparative example 16

A monovinylarene-conjugated diene copolymer and a polymer composition were prepared in the same manner as in example 10, except that a mixture of DLTP and 1076 (DLTP: 1076: 1 by weight) was used as an antioxidant.

Comparative example 17

A monovinylarene-conjugated diene copolymer and a polymer composition were prepared in the same manner as in example 10, except that a mixture of 264 and TNPP (264: TNPP ═ 1: 1 by weight) was used as an antioxidant.

TABLE 4

TABLE 5

Item	Comparative example 15	Comparative example 16	Comparative example 17
				The dosage of the anti-aging agent is wt%	0.6	0.6	0.6
Oxidative induction period, min	44	39	12
				Tear Strength (aged for 4 days), MPa	16.7	16.2	15.4
Relative elongation (aged 4 days), MPa	320	309	321
				300% tensile Strength (aged for 4 days), MPa	6.6	6.1	5.4

Example 18

In a 5L stainless steel stirring reaction kettle, 2288g of mixed solvent (mixed solution of cyclohexane and n-hexane, wherein the mass of cyclohexane/n-hexane isThe quantitative ratio was 88/12), 78g of styrene and 234g of butadiene. Using 0.78g of 2, 2-bis (tetrahydrofuryl) propane (DTHFP) as a polarity regulator, killing impurities by using n-butyllithium, and then adding 2.10mmol of n-butyllithium as an initiator to perform polymerization reaction, wherein the initiation temperature is 50 ℃, the polymerization pressure is 0.13MPa, and heat is not removed in the reaction process. The temperature of the reaction liquid in the reaction vessel reached a peak temperature of 74.5 ℃ at the time of 5 minutes of the reaction, and the polymerization pressure was 0.24MPa at this time. When the temperature reaches the peak temperature, 0.4200mmol Diethyl Pimelate (DP) is added into the reaction kettle for coupling, and after stirring for 30 minutes, 0.516mmol isopropanol is added to stop the reaction. Finally, 1.560g of 4, 4' -propylenebis (6-t-butyl-3-ethylphenol) as an antioxidant was added (i.e.,

wherein R is₁And R₂Is ethyl, R₃Ethyl, available from carbofuran technologies ltd), stirred well. The obtained glue solution is subjected to water vapor condensation to obtain the polymer composition according to the invention, wherein the molecular structure parameters of the monovinylarene-conjugated diene copolymer, the physical and mechanical properties of the polymer composition, the dynamic mechanical properties and the aging experimental data are listed in table 6.

Example 19

In a 5 l stainless steel stirring reaction kettle, 2288g of a mixed solvent (a mixed solution of cyclohexane and n-hexane, wherein the mass ratio of cyclohexane/n-hexane is 90/10), 62.4g of styrene and 249.6g of butadiene were added under the protection of high-purity nitrogen. Using 0.91g of 2,2- (bistetrahydrofuryl) propane (DTHFP) as a polarity regulator, killing impurities by using n-butyl lithium, and then adding 3.15mmol of n-butyl lithium as an initiator to perform polymerization reaction, wherein the initiation temperature is 40 ℃, the polymerization pressure is 0.12MPa, and heat is not removed in the reaction process. The temperature of the reaction liquid in the reaction vessel reached a peak temperature of 69.4 ℃ at the time of 12 minutes of the reaction, and the polymerization pressure was 0.26MPa at this time. After the temperature reached the peak temperature for 3 minutes (i.e., from the time when the temperature reached the peak temperature, at the 3 rd minute), 0.693mmol of diethyl pimelate was added to the reaction vessel for coupling, and after stirring for 30 minutes, 0.516mmol of isopropyl alcohol was added to terminate the reaction. Finally, 1.872g of 4, 4' -butylidenebis (6-tert-butyl-3-methylphenol) as an antioxidant was added thereto and stirred uniformly. The obtained glue solution is subjected to water vapor condensation to obtain the polymer composition according to the invention, wherein the molecular structure parameters of the monovinylarene-conjugated diene copolymer, the physical and mechanical properties of the polymer composition, the dynamic mechanical properties and the aging experimental data are listed in table 6.

Example 20

A polymer composition was prepared in the same manner as in example 19, except that the coupling agent was diethyl sebacate.

Example 21

A polymer composition was prepared in the same manner as in example 19, except that the coupling agent was dipropyl pimelate.

TABLE 6

The results of tables 4 to 6 confirm that the polymer compositions according to the invention have good ageing resistance.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A polymer composition comprising a monovinylarene-conjugated diene copolymer comprising structural units derived from monovinylarene and structural units derived from conjugated diene, and at least one antioxidant, characterized in that the antioxidant is selected from compounds of formula I,

in the formula I, R₁And R₂Each independently is C₁-C₃Alkyl of R₃Is C₁-C₆Alkyl groups of (a);

the content of structural units derived from monovinyl aromatic hydrocarbon is 15 to 45% by weight and the content of structural units derived from conjugated diene is 55 to 85% by weight, based on the total amount of the monovinyl aromatic hydrocarbon-conjugated diene copolymer, and the content of structural units derived from conjugated diene containing a vinyl group as a side group is 5 to 75% by weight, based on the total amount of structural units derived from conjugated diene, in the monovinyl aromatic hydrocarbon-conjugated diene copolymer,

the monovinylarene-conjugated diene copolymer is a monovinylarene-conjugated diene coupled polymer, or a monovinylarene-conjugated diene coupled polymer and a monovinylarene-conjugated diene linear copolymer, the content of the coupled polymer is 60-100 wt% based on the total amount of the monovinylarene-conjugated diene copolymer, the coupled polymer is formed by coupling the monovinylarene-conjugated diene linear copolymer with a coupling agent, the number average molecular weight of the monovinylarene-conjugated diene linear copolymer is 4-20 ten thousand, the molecular weight distribution index is 1.01-1.8, the coupling agent is one or more than two selected from epichlorohydrin and a compound shown in a formula III,

in the formula III, n is an integer of 1-12, R₅And R₆Identical or different, each independently is C₁-C₃Alkyl group of (1).

2. The polymer composition according to claim 1, wherein the antioxidant is contained in an amount of 0.1 to 1 part by weight, relative to 100 parts by weight of the monovinylarene-conjugated diene copolymer.

3. The polymer composition according to claim 2, wherein the antioxidant is contained in an amount of 0.3 to 0.8 parts by weight, relative to 100 parts by weight of the monovinylarene-conjugated diene copolymer.

4. The polymer composition according to any one of claims 1 to 3, wherein in formula I, R is₁And R₂Each independently being methyl or ethyl.

5. The polymer composition according to claim 4, wherein in formula I, R₁And R₂Is methyl.

6. The polymer composition according to any one of claims 1 to 3, wherein in formula I, R is₃Is methyl, ethyl, n-propyl or isopropyl.

7. The polymer composition according to claim 6, wherein in formula I, R₃Is n-propyl or isopropyl.

8. The polymer composition according to any one of claims 1 to 3, wherein the content of structural units derived from monovinylarene is from 16 to 40 wt% and the content of structural units derived from conjugated diene is from 60 to 74 wt%, based on the total amount of the monovinylarene-conjugated diene copolymer.

9. The polymer composition according to any one of claims 1 to 3, wherein the monovinylarene-conjugated diene copolymer has a content of conjugated diene-derived structural units containing a vinyl group as a side group of 10 to 72 wt%, based on the total amount of conjugated diene-derived structural units.

10. The polymer composition according to claim 9, wherein the monovinylarene-conjugated diene copolymer has a content of structural units derived from a conjugated diene containing a vinyl group as a side group of 13 to 70% by weight, based on the total amount of structural units derived from a conjugated diene.

11. The polymer composition according to claim 1, wherein the content of the coupled polymer is 65 to 90% by weight and the content of the monovinylarene-conjugated diene linear copolymer is 10 to 35% by weight, based on the total amount of the monovinylarene-conjugated diene copolymer.

12. The polymer composition according to claim 1 or 11, wherein the linear monovinylarene-conjugated diene copolymer has a number average molecular weight of from 5 to 18 ten thousand and a molecular weight distribution index of from 1.01 to 1.6.

13. The polymer composition of claim 12, wherein the linear monovinylarene-conjugated diene copolymer has a number average molecular weight from 5.5 to 16 ten thousand.

14. The polymer composition according to claim 1 or 11, wherein in formula III, n is an integer from 3 to 10.

15. The polymer composition according to claim 14, wherein in formula III, n is an integer from 7 to 10.

16. The polymer composition according to claim 1 or 11, wherein the compound represented by formula III is one compound or two or more compounds selected from dimethyl malonate, diethyl malonate, dipropyl malonate, dimethyl succinate, diethyl succinate, dipropyl succinate, dimethyl glutarate, diethyl glutarate, dipropyl glutarate, dimethyl adipate, diethyl adipate, dipropyl adipate, dimethyl pimelate, diethyl pimelate, dipropyl pimelate, dimethyl suberate, diethyl suberate, dipropyl suberate, dimethyl azelate, diethyl azelate, dipropyl azelate, dimethyl sebacate, diethyl sebacate, and dipropyl sebacate.

17. The polymer composition according to any one of claims 1 to 3 and 11, wherein the monovinylarene is one or more selected from compounds represented by formula II,

in the formula II, R₄Is C₆-C₂₀Aryl group of (1).

18. The polymer composition of claim 17, wherein the monovinylarene is styrene.

19. The polymer composition according to any of claims 1-3 and 11, wherein the conjugated diene is selected from C₄-C₈One or more than two of the conjugated diolefins (2).

20. The polymer composition of claim 19, wherein the conjugated diene is butadiene.

21. A method for improving aging resistance of a styrene-based thermoplastic elastomer, which comprises adding a compound represented by the formula I to the styrene-based thermoplastic elastomer,

in the formula I, R₁And R₂Each independently is C₁-C₃Alkyl of R₃Is C₁-C₆The alkyl group of (a) is,

the styrene-based thermoplastic elastomer is styrene-butadiene-styrene type thermoplastic elastomer, and the content of structural units derived from styrene is 15-45 wt% and the content of structural units derived from butadiene is 55-85 wt% based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer; the styrene-butadiene-styrene type thermoplastic elastomer has a content of a butadiene-derived structural unit containing a vinyl group as a side group of 5 to 25% by weight based on the total amount of the butadiene-derived structural units;

the styrene-butadiene-styrene type thermoplastic elastomer comprises a coupling polymer and an optional styrene-butadiene-styrene linear copolymer, wherein the content of the coupling polymer is 60-100 wt% and the content of the styrene-butadiene-styrene linear copolymer is 0-40 wt% based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer, the coupling polymer is obtained by coupling the styrene-butadiene-styrene linear copolymer with a coupling agent, the number average molecular weight of the styrene-butadiene-styrene linear copolymer is 4-10 ten thousand, and the molecular weight distribution index is less than 1.5;

the coupling agent is one or more than two of epichlorohydrin and a compound shown in a formula III,

22. The method of claim 21, wherein, in formula I, R₁And R₂Each independently being methyl or ethyl.

23. The method of claim 22, wherein, in formula I, R₁And R₂Is methyl.

24. The method of any one of claims 21-23, wherein, in formula I, R₃Is methyl, ethyl, n-propyl or isopropyl.

25. The method of claim 24, wherein, in formula I, R₃Is n-propyl or isopropyl.

26. The method of claim 21, wherein the styrenic thermoplastic elastomer is a styrene-butadiene-styrene type thermoplastic elastomer synthesized by a coupling method.

27. The method according to claim 21, wherein the content of structural units derived from styrene is 25 to 40% by weight and the content of structural units derived from butadiene is 60 to 75% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer.

28. The method according to claim 27, wherein the content of structural units derived from styrene is 30 to 35% by weight and the content of structural units derived from butadiene is 65 to 70% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer.

29. The method according to any one of claims 21 and 26 to 28, wherein the styrene-butadiene-styrene type thermoplastic elastomer has a content of a structural unit derived from butadiene containing a vinyl group as a side group of 10 to 20% by weight based on the total amount of the structural unit derived from butadiene.

30. The method according to claim 29, wherein the styrene-butadiene-styrene type thermoplastic elastomer has a content of structural units derived from butadiene containing vinyl groups as side groups of 13 to 18% by weight based on the total amount of structural units derived from butadiene.

31. The method according to claim 21, wherein the content of the coupled polymer is 65 to 90% by weight and the content of the styrene-butadiene-styrene linear copolymer is 10 to 35% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer.

32. The method according to claim 31, wherein the content of the coupled polymer is 70 to 85% by weight and the content of the styrene-butadiene-styrene linear copolymer is 15 to 30% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer.

33. The method according to claim 32, wherein the content of the coupled polymer is 76 to 82% by weight and the content of the styrene-butadiene-styrene linear copolymer is 18 to 24% by weight, based on the total amount of the styrene-butadiene-styrene type thermoplastic elastomer.

34. The process of any of claims 21, 26-28, and 31-33, wherein the styrene-butadiene-styrene linear copolymer has a number average molecular weight of 5 to 9 ten thousand and a molecular weight distribution index of 1.01 to 1.3.

35. The process of claim 34, wherein the styrene-butadiene-styrene linear copolymer has a number average molecular weight of 5.5 to 8 ten thousand and a molecular weight distribution index of 1.01 to 1.2.

36. The method of claim 35, wherein the molecular weight distribution index of the styrene-butadiene-styrene linear copolymer is 1.01 to 1.1.

37. The method of any one of claims 21, 26-28, and 31-33, wherein n is an integer from 3 to 10 in formula III.

38. The method of claim 37, wherein in formula III, n is an integer from 7 to 10.

39. The method according to any one of claims 21, 26-28, and 31-33, wherein the compound represented by formula III is one compound or two or more compounds selected from dimethyl malonate, diethyl malonate, dipropyl malonate, dimethyl succinate, diethyl succinate, dipropyl succinate, dimethyl glutarate, diethyl glutarate, dipropyl glutarate, dimethyl adipate, diethyl adipate, dipropyl adipate, dimethyl pimelate, diethyl pimelate, dipropyl pimelate, dimethyl suberate, diethyl suberate, dipropyl suberate, dimethyl azelate, diethyl azelate, dipropyl azelate, dimethyl sebacate, diethyl sebacate, and dipropyl sebacate.

40. The method according to any one of claims 21 to 23, 26 to 28 and 31 to 33, wherein the compound represented by formula I is added in an amount of 0.1 to 1 part by weight relative to 100 parts by weight of the styrenic thermoplastic elastomer.

41. The method as claimed in claim 40, wherein the compound represented by formula I is added in an amount of 0.3 to 0.8 part by weight based on 100 parts by weight of the styrenic thermoplastic elastomer.