Low-temperature-resistant brominated SIS thermoplastic elastomer and preparation method thereof

Abstract

The invention provides a preparation method of a low-temperature-resistant brominated SIS (styrene-isoprene-styrene) thermoplastic elastomer, which comprises the following steps: step 1, tribromophenyl allyl ether and N-(hydroxyalkyl) acrylamide are subjected to a block copolymerization reaction, then 4-vinyl benzoic acid is added for an acidification reaction, and a ring-opening agent is obtained; step 2, carrying out epoxidation reaction on a polyisoprene chain segment in the SIS thermoplastic elastomer to obtain epoxidized SIS; step 3, carrying out ring-opening reaction on a ring-opening agent and epoxidized SIS to obtain a low-temperature-resistant and flame-retardant brominated SIS thermoplastic elastomer; the mass ratio of the tribromophenyl allyl ether to the N-(hydroxyalkyl) acrylamide to the 4-vinyl benzoic acid is (40 to 60): (40 to 50): (3.0 to 5.0); the molar ratio of the ring-opening agent to the epoxy group in the epoxidized SIS is greater than or equal to 1. The SIS thermoplastic elastomer provided by the invention improves the non-polar problem, the peel strength of a pressure-sensitive adhesive prepared from the SIS thermoplastic elastomer is relatively high, and the SIS thermoplastic elastomer provided by the invention has relatively good low temperature resistance.

Description

Technical Field

[0001] This invention belongs to the field of styrene-based thermoplastic elastomers, specifically relating to a low-temperature resistant brominated SIS thermoplastic elastomer and its preparation method. Background Technology

[0002] SIS is a styrene-based thermoplastic elastomer composed of a styrene-isoprene-styrene triblock copolymer, with polyisoprene as the middle block. Its structure contains a methyl side chain, resulting in excellent cohesive strength and superior adhesion properties. Its microstructure determines its outstanding advantages in adhesive applications, making it a major base material for hot melt pressure-sensitive adhesives and widely used in packaging, labeling, and biomedicine. With the rapid development of new energy, electronics, and precision instruments, the annual growth rate of hot melt pressure-sensitive adhesives exceeds 13%, making the high-performance development of hot melt pressure-sensitive adhesives a current research hotspot.

[0003] However, as a non-polar polymer, SIS thermoplastic elastomers inevitably suffer from poor compatibility with polar materials, poor adhesion, poor oil resistance, and insufficient tack. As a result, the performance of SIS thermoplastic elastomers cannot meet the increasingly diverse application scenarios, becoming a bottleneck for the expansion of applications of SIS thermoplastic elastomer materials.

[0004] Polarization refers to enhancing the polarity of materials by introducing polar groups, polar side chains, or blending with polar substances, thereby improving their adhesion and oil resistance. Polarization can further broaden the application fields of SIS thermoplastic elastomers; therefore, polarization modification of SIS thermoplastic elastomers has become the most effective method to solve the aforementioned problems. Polarization mainly includes the introduction of polar monomers through polymerization and post-functionalization polarization modification. The polymerization method (mainly using living anionic polymerization) to introduce polar monomers is difficult to implement and has a narrow range of selectable polar monomers. Post-functionalization, on the other hand, mainly utilizes the unsaturated double bonds of isoprene segments in the SIS polymer molecular chain to introduce polar groups or segments. The modified products have a clear structure, relatively stable chemical properties, simple composition, and high polarization efficiency, making them relatively easy to implement and thus becoming one of the hot research directions in the polarization of SIS thermoplastic elastomers.

[0005] CN116515138A discloses a dynamic crosslinking network of spiropyran-modified SIS with mechanochromic properties. The dynamic crosslinking network SIS-SP-UPy, with spiropyran-modified SIS as the main chain, is constructed by epoxy functionalizing the double bonds of the polyisoprene (PI) blocks in the SIS (ESIS-hydroxy-functionalized SIS-OH), and using the esterification reaction of isocyanate NCO and OH. Bis-terminated NCO-functionalized spiropyran SP is used as the covalent crosslinking agent SP-NCO, and NCO-functionalized 2-ureido-4[1H]-pyrimidinone is used as the dynamic hydrogen-bonding crosslinking agent UPy-NCO. SP-NCO and UPy-NCO are then grafted onto the side chains of SIS-OH, resulting in a dynamic crosslinking network SIS-SP-UPy with both covalent and dynamic hydrogen-bonding crosslinking. This modified SIS primarily focuses on color-changing properties.

[0006] Therefore, how to improve the polarity of SIS thermoplastic elastomers to give them better application performance is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The main objective of this invention is to provide a low-temperature resistant brominated SIS thermoplastic elastomer and its preparation method, in order to solve the non-polarity problem of SIS thermoplastic elastomer, improve its compatibility with other resins, and enhance the peel strength of the pressure-sensitive adhesive subsequently prepared. Moreover, the brominated SIS thermoplastic elastomer of this invention has good low-temperature resistance, which can meet the low-temperature requirements of pressure-sensitive adhesives in new energy, high-end electronics industry and biomedicine.

[0008] To achieve the above objectives, the present invention provides a method for preparing a low-temperature resistant brominated SIS thermoplastic elastomer, comprising the following steps:

[0009] Step 1 involves a block copolymerization reaction of tribromophenyl allyl ether and N-(hydroxyalkyl)acrylamide, followed by an acidification reaction with the addition of 4-vinylbenzoic acid to obtain a ring-opening agent.

[0010] Step 2: The polyisoprene segments in the SIS thermoplastic elastomer undergo an epoxidation reaction to obtain epoxidized SIS;

[0011] Step 3: The ring-opening agent is reacted with the epoxidized SIS to obtain a low-temperature resistant, flame-retardant brominated SIS thermoplastic elastomer.

[0012] The mass ratio of the tribromophenyl allyl ether, N-(hydroxyalkyl)acrylamide and 4-vinylbenzoic acid is (40-60):(40-50):(3.0-5.0); the molar ratio of the ring-opening agent to the epoxy group in the epoxidized SIS is greater than or equal to 1.

[0013] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention, wherein step 1 comprises: subjecting the tribromophenyl allyl ether to a polymerization reaction; after the conversion rate of the tribromophenyl allyl ether monomer reaches 95%-100%, adding N-(hydroxyalkyl)acrylamide to a polymerization reaction; after the conversion rate of the N-(hydroxyalkyl)acrylamide monomer reaches 95%, adding 4-vinylbenzoic acid to an acidification reaction to obtain a ring-opening agent; the tribromophenyl allyl ether has the following structure:

[0014]

[0015] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention comprises the following: the polymerization reaction of the tribromophenyl allyl ether is carried out in a first solvent under the action of an initiator and a structure modifier; the initiator is a hydrocarbon monolithium compound, the structure modifier is a polar organic compound, and the first solvent is a hydrocarbon solvent; the mass ratio of the tribromophenyl allyl ether, N-(hydroxyalkyl)acrylamide, and 4-vinylbenzoic acid is (50-60):(40-50):(3.0-5.0); and the molar ratio of the structure modifier to the initiator is (1.0-2.0):1.

[0016] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention includes a block copolymerization reaction at a temperature of 70–80°C, an acidification reaction at a temperature of 70–80°C, and an acidification reaction time of 30–40 min; the N-(hydroxyalkyl)acrylamide is selected from one of N-(2-hydroxyethyl)acrylamide, N-(3-hydroxypropyl)acrylamide, and N-(4-hydroxybutyl)acrylamide.

[0017] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention, wherein the ring-opening agent has the following structure:

[0018]

[0019] Where R is a C1 to C3 straight-chain alkyl group; n and m are the number of repeating units, n≥1 and m≥1.

[0020] The method for preparing low-temperature resistant brominated SIS thermoplastic elastomer according to the present invention, wherein the ring-opening agent has a number-average molecular weight of 3000-4000 and a molecular weight distribution of 1.89-2.18.

[0021] The method for preparing low-temperature resistant, brominated SIS thermoplastic elastomer according to the present invention, wherein the epoxidation reaction of the polyisoprene segment in the SIS thermoplastic elastomer is carried out in a second solvent under the action of organic acid and peroxide; the molar ratio of SIS thermoplastic elastomer, organic acid and peroxide is 100:(5-10):(20-40).

[0022] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention comprises: the organic acid being selected from at least one of formic acid, acetic acid, benzoic acid, and salicylic acid; the molar ratio of the organic acid to the SIS thermoplastic elastomer being (0.02-0.5):1; the peroxide being hydrogen peroxide and / or peracetic acid; the molar ratio of the peroxide to the SIS thermoplastic elastomer being (0.1-1.5):1; and the second solvent being selected from at least one of chlorobenzene, benzene, toluene, xylene, chloroform, acetone, and ethylbenzene.

[0023] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention, wherein the epoxy degree of the epoxidized SIS is 5% to 8%.

[0024] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention includes a ring-opening reaction between the ring-opening agent and the epoxidized SIS carried out under the action of a ring-opening catalyst, wherein the ring-opening catalyst is selected from at least one of zirconium tetrachloride, trifluoromethanesulfonic acid, and imidazole; the molar ratio of the ring-opening catalyst to the epoxy groups in the epoxidized SIS is (0.01-0.4):1; and the molar ratio of the ring-opening agent to the epoxy groups in the epoxidized SIS is (1.1-1.5):1.

[0025] The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer of the present invention includes the following: before mixing the epoxidized SIS with the ring-opening agent, the epoxidized SIS is first mixed with an organic solvent, and the pH value of the mixture is adjusted to 1-5; the molar ratio of epoxy groups, ring-opening agent and ring-opening catalyst in the epoxidized SIS is 100:(100-140):(3-9).

[0026] The method for preparing low-temperature resistant brominated SIS thermoplastic elastomer according to the present invention includes adjusting the pH value of the mixture to 1-5 using an acid anhydride, wherein the acid anhydride is selected from one or more of propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride, and octanoic anhydride.

[0027] The method for preparing the low-temperature resistant brominated SIS thermoplastic elastomer of the present invention includes a ring-opening reaction temperature of 140-150°C and a ring-opening reaction time of 3.0-4.0 hr.

[0028] To achieve the above objectives, the present invention also provides a low-temperature resistant brominated SIS thermoplastic elastomer obtained by the above preparation method.

[0029] The beneficial effects of this invention are:

[0030] (1) This invention uses tribromophenyl allyl ether and N-(hydroxyalkyl)acrylamide as reactants and synthesizes a macromolecular polar brominated ring-opening agent by end acidification with 4-vinylbenzoic acid. This macromolecular polar brominated ring-opening agent integrates ether groups, amide groups and hydroxyl groups containing long carbon chains into a single macromolecular chain. It fully utilizes the "aggregation effect" of macromolecules, the "group effect" and "structural effect" of long carbon chain hydroxyl and amide groups, which can destroy the regularity and crystallinity of SIS thermoplastic elastomer chain segments, effectively reduce the glass transition temperature (Tg) of SIS thermoplastic elastomers, and can prepare low-temperature resistant brominated SIS thermoplastic elastomers with high breakage rate in low-temperature environments below -20℃.

[0031] (2) The macromolecular polar brominated ring-opening agent contains a certain amount of benzene ring. The benzene ring has the characteristics of high rigidity and large steric hindrance, which can avoid the problem that the molecular weight distribution of SIS thermoplastic elastomer becomes wider due to branching, thereby causing the tensile strength of SIS thermoplastic elastomer raw rubber to decrease. This allows the low-temperature resistant brominated SIS thermoplastic elastomer to maintain sufficient raw rubber tensile strength.

[0032] (3) In the preparation process of low-temperature resistant brominated SIS thermoplastic elastomer, there is no emission of volatile organic compounds (VOCs) and by-product HBr. The preparation method is green and environmentally friendly, with low addition amount and significant modification effect, and is suitable for industrial production. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods not specified in the following embodiments are generally performed under conventional conditions. Unless otherwise specified, "parts" in the present invention refer to parts by mass, and "ratio" refers to mass ratio.

[0034] This invention first synthesizes a macromolecular polar brominated ring-opening agent using 4-vinylbenzoic acid, tribromophenylallyl ether, and N-(hydroxyalkyl)acrylamide; secondly, it performs an epoxidation reaction on the PI (polyisoprene) segments containing double bonds in the SIS thermoplastic elastomer to obtain epoxidized SIS; finally, it performs a ring-opening reaction between the macromolecular polar brominated ring-opening agent and the epoxidized SIS to prepare a low-temperature resistant brominated SIS thermoplastic elastomer.

[0035] In one embodiment, the present invention provides a method for preparing a low-temperature resistant brominated SIS thermoplastic elastomer, comprising the following steps:

[0036] Step 1 involves a block copolymerization reaction of tribromophenyl allyl ether and N-(hydroxyalkyl)acrylamide, followed by an acidification reaction with the addition of 4-vinylbenzoic acid to obtain a ring-opening agent.

[0037] Step 2: The polyisoprene segments in the SIS thermoplastic elastomer undergo an epoxidation reaction to obtain epoxidized SIS;

[0038] Step 3: The ring-opening agent is reacted with the epoxidized SIS to obtain a low-temperature resistant, flame-retardant brominated SIS thermoplastic elastomer.

[0039] The mass ratio of the tribromophenyl allyl ether, N-(hydroxyalkyl)acrylamide and 4-vinylbenzoic acid is (40-60):(40-50):(3.0-5.0).

[0040] The SIS thermoplastic elastomer of this invention improves the non-polarity problem, has good compatibility with other resins, and the pressure-sensitive adhesive prepared from it has high peel strength. Moreover, the SIS thermoplastic elastomer of this invention has good low-temperature resistance, which can meet the low-temperature requirements of pressure-sensitive adhesives in new energy, high-end electronics industry and biomedicine.

[0041] In one embodiment, step 1 is: to polymerize tribromophenyl allyl ether (i.e., 2,4,6-tribromophenyl allyl ether), then add N-(hydroxyalkyl)acrylamide for further polymerization, and then add 4-vinylbenzoic acid for acidification to obtain a ring-opening agent.

[0042] Step 1 of this invention is carried out in an inert gas atmosphere. This invention does not impose any particular limitation on the inert gas, as long as it does not affect the reaction, such as nitrogen or argon. In another embodiment, after the conversion rate of tribromophenyl allyl ether monomer reaches 95%-100%, and further reaches 100%, N-(hydroxyalkyl)acrylamide is added. After the conversion rate of N-(hydroxyalkyl)acrylamide monomer reaches more than 95%, 4-vinylbenzoic acid is added for single-end capping. After the reaction, the slurry is poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent.

[0043] In yet another embodiment, the polymerization of tribromophenyl allyl ether is carried out in a first solvent under the action of an initiator and a structure modifier.

[0044] In this invention, tribromophenyl allyl ether has the following structure:

[0045]

[0046] The present invention does not specifically limit the position of the three bromine atoms on the benzene ring in tribromophenyl allyl ether, and they can be any three substitution positions at the 2, 3, 4, 5, and 6 positions, for example, 2,4,6-tribromophenyl allyl ether, 3,4,5-tribromophenyl allyl ether, etc.

[0047] The initiator can be a hydrocarbon monolithium compound, such as R′Li, where R′ is a saturated aliphatic hydrocarbon group containing 1-20 carbon atoms, an alicyclic hydrocarbon group containing 2-20 carbon atoms, an aromatic hydrocarbon group having 6-20 carbon atoms, or a complex group of the above groups. In one embodiment, the hydrocarbon monolithium compound is selected from one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthenelithium, cyclohexyllithium, and dodecyllithium, preferably n-butyllithium. The present invention does not particularly limit the amount of initiator added. In one embodiment, it is determined by the molecular weight of the polar brominated ring-opening agent of the target product macromolecule, for example, by calculating the amount of hydrocarbon monolithium compound using the following formula:

[0048] The molar mass (mol) of a hydrocarbon-based monolithium compound = total mass of the gel m (g) / molecular weight M (g / mol)

[0049] The total mass of the gel refers to the total mass of tribromophenyl allyl ether and N-(hydroxyalkyl)acrylamide, and the molecular weight refers to the molecular weight of the target product's macromolecular polar brominated ring-opening agent.

[0050] The structure modifier is a polar organic compound capable of producing a solvation effect in the polymerization system. In one embodiment, the polar organic compound is selected from diethylene glycol dimethyl ether (DGE), tetrahydrofuran (THF), diethyl ether, ethyl methyl ether, anisole, diphenyl ether, diethylene glycol dimethyl ether (DME), and triethylamine, preferably tetrahydrofuran (THF).

[0051] The first solvent is a hydrocarbon solvent, which can be a straight-chain alkane, aromatic hydrocarbon, or cycloalkanes, such as one selected from pentane, hexane, octane, heptane, and cyclohexane, with cyclohexane being preferred.

[0052] In one embodiment, the mass ratio of the first solvent, tribromophenyl allyl ether, N-(4-hydroxybutyl)acrylamide, and 4-vinylbenzoic acid is (400–500):(50.0–60.0):(40.0–50.0):(3.0–5.0); the molar ratio of the structure modifier to the initiator is (1.0–2.0):1. The N-(hydroxyalkyl)acrylamide is selected from N-(2-hydroxyethyl)acrylamide, N-(3-hydroxypropyl)acrylamide, and N-(4-hydroxybutyl)acrylamide, preferably N-(4-hydroxybutyl)acrylamide.

[0053] In one embodiment, the block copolymerization reaction is carried out at a temperature of 70–80°C, the acidification reaction is carried out at a temperature of 70–80°C, and the acidification reaction takes 30–40 minutes. In another embodiment, the reaction is carried out under stirring at a speed of 500–600 rpm.

[0054] In one specific embodiment, step 1 is as follows: In an inert gas purging process, a first solvent, tribromophenyl allyl ether, and a structure modifier are sequentially added to the polymerization reactor. The mixture is stirred and heated, and then an initiator is added to react. When the conversion rate of tribromophenyl allyl ether monomer reaches 100%, N-(hydroxyalkyl)acrylamide is added to the polymerization reactor to react. When the conversion rate of N-(hydroxyalkyl)acrylamide monomer reaches 97% or more but less than 100%, 4-vinylbenzoic acid is added to the polymerization reactor to carry out an acidification reaction. After the reaction, the slurry is poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent.

[0055] In one embodiment, the ring-opening agent of the present invention has the following structure:

[0056]

[0057] Where R is a C1 to C3 straight-chain alkyl group; n and m are the number of repeating units, 10 ≥ n ≥ 1, 10 ≥ m ≥ 1.

[0058] In another embodiment, the ring-opening agent has a number-average molecular weight (Mn) of 3000 to 4000 and a molecular weight distribution of 1.89 to 2.18.

[0059] Step 2 involves epoxidizing the polyisoprene segments in the SIS thermoplastic elastomer to obtain epoxidized SIS.

[0060] The present invention does not particularly limit the SIS thermoplastic elastomer. In one embodiment, the number average molecular weight (Mn) of the SIS thermoplastic elastomer is 130,000 to 200,000.

[0061] This invention does not specifically limit the method for epoxidation of polyisoprene segments in SIS thermoplastic elastomers; conventional methods in the art are acceptable. In one embodiment, the epoxidation reaction of polyisoprene segments in SIS thermoplastic elastomers is carried out in a second solvent under the action of an organic acid and a peroxide. The organic acid may be selected from at least one of formic acid, acetic acid, benzoic acid, and salicylic acid, and the molar ratio of the organic acid to the SIS thermoplastic elastomer is (0.02–0.5):1, preferably (0.05–0.10):1; the peroxide may be hydrogen peroxide and / or peracetic acid, and the molar ratio of the peroxide to the SIS thermoplastic elastomer is (0.1–1.5):1, preferably (0.2–0.4):1; the second solvent may be selected from at least one of chlorobenzene, benzene, toluene, xylene, chloroform, acetone, and ethylbenzene. The molar ratio of the SIS thermoplastic elastomer, organic acid, and peroxide is 100:(5–10):(20–40).

[0062] In one embodiment, the SIS thermoplastic elastomer is mixed with a second solvent to form a SIS thermoplastic elastomer solution, which is then added to a reaction vessel. Organic acid and peroxide are then added sequentially to the solution to carry out an epoxidation reaction. The resulting product is precipitated with ethanol, washed, and dried to obtain an epoxidized SIS thermoplastic elastomer.

[0063] In another embodiment, the mass concentration of the SIS thermoplastic elastomer in the SIS thermoplastic elastomer solution is 1 wt% to 15 wt%, preferably 5 wt% to 10 wt%.

[0064] In one embodiment, the epoxidation reaction temperature is 60–70°C, and the epoxidation reaction time is 3.0–5.0 hours. In another embodiment, the epoxy degree of the epoxidized SIS is 5%–8%. This invention grafts the homopolymer segments of the ring-opening agent onto the PI (isoprene homopolymer) segments of the SIS thermoplastic elastomer through a ring-opening reaction of carboxyl and epoxy groups. During the reaction, if the epoxy degree of the epoxidized SIS thermoplastic elastomer is too high, it easily leads to extensive entanglement of the branches, causing gelation and impairing the ductility of the SIS; if the epoxy degree is too low, the reaction introduces fewer bromine-containing branches, resulting in an insignificant modification effect. Therefore, the epoxy degree of the epoxidized SIS thermoplastic elastomer of this invention is 5%–8%.

[0065] The degree of epoxidation in epoxidized SIS is also called epoxy degree. Epoxy degree refers to the extent to which unsaturated double bonds in SIS are epoxidized; in other words, it is the percentage of epoxy groups in epoxidized SIS compared to the number of unsaturated double bonds in the unepoxidized SIS. Epoxy degree is an important indicator of the degree of epoxidation in epoxidized SIS, and it is usually measured accurately using NMR.

[0066] Step 3 involves reacting the ring-opening agent with the epoxidized SIS to obtain a low-temperature resistant, flame-retardant brominated SIS thermoplastic elastomer.

[0067] In one embodiment, the ring-opening reaction between the ring-opening agent and the epoxidized SIS is carried out in the presence of a ring-opening catalyst. The ring-opening catalyst is selected from at least one of zirconium tetrachloride (ZrCl4), trifluoromethanesulfonic acid, and imidazole, preferably zirconium tetrachloride (ZrCl4). The molar ratio of the ring-opening catalyst to the epoxy groups in the epoxidized SIS is (0.01–0.4):1, preferably (0.04–0.1):1. To ensure that the ring-opening agent can be fully grafted onto the thermoplastic elasticity of the SIS, the molar number of carboxyl groups in the ring-opening agent needs to be greater than the molar number of epoxy groups in the epoxidized SIS. Therefore, the molar ratio of the ring-opening agent to the epoxy groups in the epoxidized SIS is (1.1–1.5):1.

[0068] In one embodiment, epoxidized SIS is mixed with an organic solvent to prepare an epoxidized SIS thermoplastic elastomer solution, which is then added to a reaction vessel. The pH of the mixture is adjusted to 1-5, a ring-opening agent and a ring-opening catalyst are added, and the mixture is heated to carry out a ring-opening reaction. The resulting mixture is precipitated with ethanol, washed, and dried to obtain a low-temperature resistant, flame-retardant brominated SIS thermoplastic elastomer. The precipitation, washing, and drying processes are well known to those skilled in the art and can be reasonably set according to the conditions in the brominated SIS thermoplastic elastomer preparation process; this invention does not impose any particular limitations.

[0069] In one embodiment, the mass concentration of the epoxy SIS thermoplastic elastomer in the epoxidized SIS thermoplastic elastomer solution is 1.0 wt% to 10.0 wt%, preferably 3.0 wt% to 5.0 wt%. The organic solvent may be selected from at least one of chlorobenzene, benzene, toluene, xylene, chloroform, acetone, and ethylbenzene. The molar ratio of epoxy groups, ring-opening agents, and ring-opening catalysts in the epoxidized SIS is 100:(110-150):(4-10). In another embodiment, an acid anhydride is used to adjust the pH of the mixture, and the acid anhydride is selected from one or more of propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride, or octanoic anhydride.

[0070] In another embodiment, the ring-opening reaction temperature is 140–150°C, and the ring-opening reaction time is 3.0–4.0 hr.

[0071] The preparation process of the low-temperature resistant brominated SIS thermoplastic elastomer of this invention is carried out in an oxygen-free, anhydrous, and inert gas environment. The inert gas can be nitrogen or a gas of a group 0 element in the periodic table except radon, preferably argon. The reaction apparatus can be purged before the reaction, for example, 3 to 5 times. The reaction apparatus of this invention can be a reaction vessel, such as a loop reactor or a batch reactor, preferably a batch reactor.

[0072] This invention also provides a low-temperature resistant, brominated SIS thermoplastic elastomer obtained by the above preparation method. Compared with SIS thermoplastic elastomer, it not only possesses a certain degree of polarity, improving its compatibility with other polar resins and significantly enhancing the peel strength of the subsequently prepared pressure-sensitive adhesive, but also effectively lowers its glass transition temperature (Tg), improving low-temperature resistance and avoiding low breakage rates and debonding in low-temperature environments below -20°C. This meets the low-temperature performance requirements of pressure-sensitive adhesives in new energy, high-end electronics, and biomedical industries. Furthermore, the low-temperature resistant, brominated SIS thermoplastic elastomer of this invention maintains sufficient raw rubber tensile strength of SIS thermoplastic elastomer.

[0073] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0074] (1) Source of raw materials:

[0075] SIS thermoplastic elastomers, China Petroleum & Chemical Research Institute

[0076] N-(4-hydroxybutyl)acrylamide, 99% purity, Shanghai Jizhi Biochemical Technology Co., Ltd.

[0077] 3,4,5-Tribromophenylallyl ether, polymerization grade, Hubei Xinghengye Technology Co., Ltd.

[0078] 2,4,6-Tribromophenylallyl ether, polymerization grade, Hubei Jiahuixingcheng Biotechnology Co., Ltd.

[0079] 4-Vinylbenzoic acid, 98% purity, Condis Chemical (Hubei) Co., Ltd.

[0080] Zirconium chloride (ZrCl4), 99% purity, Wuxi Yaodexin Chemical Products Co., Ltd.

[0081] n-Butyllithium, 98% purity, Nanjing Tonglian Chemical Co., Ltd.

[0082] All other reagents are commercially available industrial products.

[0083] (2) Analysis and testing methods:

[0084] Molecular weight and molecular weight distribution were determined using a Waters 2414 gel permeation chromatography (GPC) system (USA). A polytribromophenyl allyl ether standard was used as the calibration curve. The mobile phase was tetrahydrofuran, the column temperature was 40℃, the sample concentration was 1 mg / mL, the injection volume was 50 μL, the elution time was 40 min, and the flow rate was 1 mL / min. -1 .

[0085] Determination of epoxy content: 1H NMR spectroscopy was used. A Shimadzu UNITY 300 NMR spectrometer was used. The prepared epoxidized SIS was dissolved in deuterated chloroform to prepare a 1% (w / w) solution for determination.

[0086] Formula for calculating epoxy degree in epoxidized SIS (ESIS):

[0087]

[0088] Among them, A 2.70 A is the integrated area of ​​the epoxy group peak in ESIS. 5.12 Let be the integral area of ​​the unsaturated double bond C=C in ESIS.

[0089] Preparation of standard samples: The low-temperature resistant, brominated SIS thermoplastic elastomer was cut into small pieces and placed in a beaker. It was heated in an oven at 180°C for 40 minutes. After the pieces were completely melted, they were coated. The coating substrate was release paper. After coating, a PET film was simultaneously attached to the release paper. The PET film thickness was 100µm, the release paper thickness was 50µm, and the coating thickness was 30-40µm. The coated PET film was cured at room temperature for 24 hours before product performance testing was conducted.

[0090] Determination of glass transition temperature (Tg): The glass transition temperature of the product was measured using DSC. The instrument model was DSC1, manufactured by Mettler AG, Switzerland. The heating range was -80 to 80 °C, and the heating rate was 10 °C / min.

[0091] Determination of breakage rate: After the brominated SIS thermoplastic elastomer pressure-sensitive tape is coated, it is cured at room temperature for 24 hours and then attached to the cardboard of the packaging box. Roller pressing is performed using the rollers in GB / T 4851-2014 Test Method for Adhesive Tape Holding Power. The bonded board is then placed in a refrigerator at -20℃ for 2 hours. After that, it is peeled off at 90° in the refrigerator. The percentage of the cardboard area that is broken in the bonded area is the breakage rate.

[0092] Peel strength test: Determined according to the method in standard GB / T 2792-2014.

[0093] Tensile strength: determined according to the method in standard GB / T528-2009.

[0094] Example 1

[0095] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2000g of cyclohexane, 250g of 3,4,5-tribromophenylallyl ether and 168mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 500rpm. When the temperature was raised to 70℃, 168mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reached 100%, 250g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reached 97%, 15g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 30min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn = 3000, Mw / Mn = 1.89).

[0096] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a 5.0 wt% SIS thermoplastic elastomer solution, which was then added to a reaction vessel. 0.05 mol of formic acid and 0.2 mol of hydrogen peroxide were then added sequentially, and the mixture was heated to 60 °C for 3.0 h for epoxidation. The resulting product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxide content of 5.0%).

[0097] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 3.0 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 1.0 with propionic anhydride. Then, 1.1 mol of a macromolecular polar brominated ring-opening agent and 0.04 mol of ZrCl4 were added. The mixture was heated to 140℃ for a ring-opening reaction for 3.0 hours. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0098] Example 2

[0099] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2100g of cyclohexane, 260g of 3,4,5-tribromophenylallyl ether and 184mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 530rpm. When the temperature was raised to 72℃, 153mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reached 100%, 240g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reached 97%, 17g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 32min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3300, Mw / Mn is 1.93).

[0100] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a 6.0 wt% SIS thermoplastic elastomer solution, which was then added to a reaction vessel. 0.06 mol of formic acid and 0.26 mol of hydrogen peroxide were then added sequentially, and the mixture was heated to 68 °C for 3.6 hours for epoxidation. The resulting product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxy degree of 5.7%).

[0101] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 3.5 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 2.2 with propionic anhydride. 1.23 mol of a macromolecular polar brominated ring-opening agent and 0.05 mol of ZrCl4 were added. The mixture was heated to 142℃ for 3.2 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0102] Example 3

[0103] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2200g of cyclohexane, 270g of 3,4,5-tribromophenylallyl ether and 203mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 540rpm. When the temperature was raised to 75℃, 144mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reached 100%, 230g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reached 97%, 19g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 34min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3500, Mw / Mn is 2.04).

[0104] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a 7.0 wt% SIS thermoplastic elastomer solution, which was then added to a reaction vessel. 0.07 mol of formic acid and 0.29 mol of hydrogen peroxide were then added sequentially, and the mixture was heated to 65 °C for 4.0 h for epoxidation. The resulting product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxy degree of 6.3%).

[0105] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.0 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 3.4 with propionic anhydride. Then, 1.31 mol of a macromolecular polar brominated ring-opening agent and 0.07 mol of ZrCl4 were added. The mixture was heated to 145℃ for 3.5 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0106] Example 4

[0107] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2300g of cyclohexane, 280g of 3,4,5-tribromophenylallyl ether and 230mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 560rpm. When the temperature was raised to 76℃, 136mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reached 100%, 220g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reached 97%, 21g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 37min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3700, Mw / Mn is 2.09).

[0108] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a SIS thermoplastic elastomer solution with a mass fraction of 8.0 wt%. The solution was added to a reaction vessel, and then 0.08 mol of formic acid and 0.33 mol of hydrogen peroxide were added sequentially. The temperature was raised to 67°C and the epoxidation reaction was carried out for 4.5 hours. The product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxy degree of 7.1%).

[0109] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.1 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 3.9 with propionic anhydride. Then, 1.39 mol of a macromolecular polar brominated ring-opening agent and 0.08 mol of ZrCl4 were added. The mixture was heated to 147°C for 3.7 hours to carry out the ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0110] Example 5

[0111] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2400g of cyclohexane, 290g of 2,4,6-tribromophenylallyl ether and 238mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 580rpm. When the temperature was raised to 78℃, 133mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 2,4,6-tribromophenylallyl ether monomer reached 100%, 210g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reached 97%, 23g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 58min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3800, Mw / Mn is 2.13).

[0112] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a 9.2 wt% SIS thermoplastic elastomer solution, which was then added to a reaction vessel. 0.09 mol of formic acid and 0.38 mol of hydrogen peroxide were then added sequentially, and the mixture was heated to 69 °C for 4.8 hours for epoxidation. The resulting product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxy degree of 7.7%).

[0113] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.7 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 4.6 with propionic anhydride. Then, 1.43 mol of a macromolecular polar brominated ring-opening agent and 0.09 mol of ZrCl4 were added. The mixture was heated to 148℃ for 3.8 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0114] Example 6

[0115] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2500g of cyclohexane, 300g of 2,4,6-tribromophenylallyl ether and 252mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 600rpm. When the temperature was raised to 80℃, 126mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 2,4,6-tribromophenylallyl ether monomer reached 100%, 200g of N-(4-hydroxybutyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reached 97%, 25g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 40min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 4000, Mw / Mn is 2.18).

[0116] (II) Preparation of epoxidized SIS thermoplastic elastomer: 1 mol of SIS thermoplastic elastomer was dissolved in toluene to prepare a 10.0 wt% SIS thermoplastic elastomer solution, which was then added to a reaction vessel. 0.10 mol of formic acid and 0.40 mol of hydrogen peroxide were added sequentially, and the mixture was heated to 70 °C for 5.0 h for epoxidation. The resulting product was precipitated with ethanol, washed, and dried to obtain epoxidized SIS thermoplastic elastomer (epoxy degree of 8.0%).

[0117] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in chlorobenzene to prepare a 5.0 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 5.0 with butyric anhydride. Then, 1.50 mol of a macromolecular polar brominated ring-opening agent and 0.10 mol of ZrCl4 were added. The mixture was heated to 150℃ for 4.0 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0118] Example 7

[0119] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2450g of cyclohexane, 294g of 2,4,6-tribromophenylallyl ether and 242mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 580rpm. When the temperature was raised to 78℃, 130mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 2,4,6-tribromophenylallyl ether monomer reached 98%, 210g of N-(4-hydroxyethyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxyethyl)acrylamide monomer reached 96%, 23g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 58min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3820, Mw / Mn is 2.11).

[0120] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 5.

[0121] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.8 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 4.8 with propionic anhydride. Then, 1.46 mol of a macromolecular polar brominated ring-opening agent and 0.09 mol of ZrCl4 were added. The mixture was heated to 149℃ for a ring-opening reaction for 3.9 hours. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0122] Example 8

[0123] (I) Preparation of macromolecular polar brominated ring-opening agent: In a jacketed 4L stainless steel reactor, an inert gas was introduced for purging. 2500g of cyclohexane, 300g of 2,4,6-tribromophenylallyl ether and 255mmol of THF were added sequentially to the polymerization reactor. The stirring speed was 600rpm. When the temperature was raised to 80℃, 129mmol of n-butyllithium was added to carry out the reaction. When the conversion rate of 2,4,6-tribromophenylallyl ether monomer reached 95%, 200g of N-(3-hydroxypropyl)acrylamide was added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxypropyl)acrylamide monomer reached 98%, 25g of 4-vinylbenzoic acid was added to the polymerization reactor for acidification reaction for 40min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent (Mn is 3910, Mw / Mn is 2.16).

[0124] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 6.

[0125] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in chlorobenzene to prepare a 5.0 wt% epoxidized SIS thermoplastic elastomer solution. This solution was added to a reaction vessel, and the pH of the solution was adjusted to 5.0 with butyric anhydride. Then, 1.48 mol of a macromolecular polar brominated ring-opening agent and 0.10 mol of ZrCl4 were added. The mixture was heated to 150℃ for 4.0 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0126] Comparative Example 1

[0127] (I) Preparation of macromolecular polar brominated ring-opening agent: Other conditions are the same as in Example 1, except that the amount of 4-vinylbenzoic acid added in the preparation of the macromolecular polar brominated ring-opening agent is 10.0 g. That is: in a jacketed 4L stainless steel reactor, inert gas is introduced for purging, and 2000 g of cyclohexane, 250 g of 3,4,5-tribromophenylallyl ether and 168 mmol of THF are added to the polymerization reactor in sequence. The stirring speed is 500 rpm, and when the temperature is raised to 70°C, 168 mmol of n-butyllithium is added to react. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reaches 100%, 250 g of N-(4-hydroxybutyl)acrylamide is added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reaches 97%, 10 g of N-(4-hydroxybutyl)acrylamide monomer is added to the polymerization reactor. 4-Vinylbenzoic acid was subjected to an acidification reaction for 30 min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent a (Mn is 2980, Mw / Mn is 1.87).

[0128] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 1.

[0129] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 1, except that a macromolecular polar brominated ring-opening agent was not added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer. Instead, a macromolecular polar brominated ring-opening agent a was added in an amount of 1.1 mol. Specifically, an epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 3.0 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to a reaction vessel. The pH of the solution was adjusted to 1.0 with propionic anhydride. Then, 1.1 mol of macromolecular polar brominated ring-opening agent a and 0.04 mol of ZrCl4 were added. The mixture was heated to 140°C for 3.0 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested performance is shown in Table 1.

[0130] Comparative Example 2

[0131] (I) Preparation of macromolecular polar brominated ring-opening agent: Other conditions are the same as in Example 2, except that 3,4,5-tribromophenylallyl ether is not added in the preparation of the macromolecular polar brominated ring-opening agent. Instead, 260g of 3,5-dibromostyrene is added. That is, in a jacketed 4L stainless steel reactor, an inert gas is introduced for purging. 2100g of cyclohexane, 260g of 3,5-dibromostyrene, and 184mmol of THF are added sequentially to the polymerization reactor. The stirring speed is 530rpm. When the temperature is raised to 72°C, 153mmol of n-butyllithium is added to carry out the reaction. When the conversion rate of 3,5-dibromostyrene monomer reaches 100%, 240g of N-(4-hydroxybutyl)acrylamide is added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reaches 97%, 17g of N-(4-hydroxybutyl)acrylamide monomer is added to the polymerization reactor. 4-Vinylbenzoic acid was subjected to an acidification reaction for 32 min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent b (Mn is 3200, Mw / Mn is 1.91).

[0132] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 2.

[0133] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 2, except that a macromolecular polar brominated ring-opening agent was not added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer. Instead, a macromolecular polar brominated ring-opening agent b was added in an amount of 1.23 mol. Specifically, an epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 3.5 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to a reaction vessel. When the pH of the solution was adjusted to 2.2 with propionic anhydride, 1.23 mol of macromolecular polar brominated ring-opening agent b and 0.05 mol of ZrCl4 were added. The mixture was heated to 142°C for 3.2 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0134] Comparative Example 3

[0135] (I) Preparation of macromolecular polar brominated ring-opening agent: Other conditions are the same as in Example 3, except that the amount of 3,4,5-tribromophenylallyl ether added in the preparation of the macromolecular polar brominated ring-opening agent is 100g. That is: in a 4L stainless steel reactor with a jacket, an inert gas is introduced for purging, and 2200g of cyclohexane, 100g of 3,4,5-tribromophenylallyl ether and 203mmol of THF are added to the polymerization reactor in sequence. The stirring speed is 540rpm, and when the temperature is raised to 75°C, 144mmol of n-butyllithium is added to react. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reaches 100%, 230g of N-(4-hydroxybutyl)acrylamide is added to the polymerization reactor to continue the reaction. When the conversion rate of N-(4-hydroxybutyl)acrylamide monomer reaches 97%, 19g of N-butyllithium is added to the polymerization reactor. 4-Vinylbenzoic acid was subjected to an acidification reaction for 34 min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent c (Mn is 3000, Mw / Mn is 2.01).

[0136] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 3.

[0137] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 3, except that a macromolecular polar brominated ring-opening agent was not added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer. Instead, a macromolecular polar brominated ring-opening agent c was added in an amount of 1.31 mol. Specifically, an epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.0 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to a reaction vessel. The pH of the solution was adjusted to 3.4 with propionic anhydride. Then, 1.31 mol of macromolecular polar brominated ring-opening agent c and 0.07 mol of ZrCl4 were added. The mixture was heated to 145°C for 3.5 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0138] Comparative Example 4

[0139] (I) Preparation of macromolecular polar brominated ring-opening agent: Other conditions are the same as in Example 4, except that N-(4-hydroxybutyl)acrylamide is not added during the preparation of the macromolecular polar brominated ring-opening agent. Instead, 220g of acrylamide is added. That is, in a 4L stainless steel reactor with a jacket, an inert gas is introduced for purging. 2300g of cyclohexane, 280g of 3,4,5-tribromophenylallyl ether, and 230mmol of THF are added sequentially to the polymerization reactor. The stirring speed is 560rpm. When the temperature is raised to 76°C, 136mmol of n-butyllithium is added to carry out the reaction. When the conversion rate of 3,4,5-tribromophenylallyl ether monomer reaches 100%, 220g of acrylamide is added to the polymerization reactor to continue the reaction. When the conversion rate of acrylamide monomer reaches 97%, 21g of acrylamide is added to the polymerization reactor. 4-Vinylbenzoic acid was subjected to an acidification reaction for 37 min. After the reaction, the slurry was poured out, coagulated, washed, and vacuum dried to obtain a macromolecular polar brominated ring-opening agent d (Mn is 3600, Mw / Mn is 2.05).

[0140] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 4.

[0141] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 4, except that a macromolecular polar brominated ring-opening agent was not added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer. Instead, a macromolecular polar brominated ring-opening agent d was added in an amount of 1.39 mol. Specifically, an epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.1 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to a reaction vessel. The pH of the solution was adjusted to 3.9 with propionic anhydride. Then, 1.39 mol of macromolecular polar brominated ring-opening agent d and 0.08 mol of ZrCl4 were added. The mixture was heated to 147°C for 3.7 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0142] Comparative Example 5

[0143] (I) Preparation of macromolecular polar brominated ring-opening agent: Other conditions are the same as in Example 5, except that N-(4-hydroxybutyl)acrylamide is not added in the preparation of macromolecular polar brominated ring-opening agent. That is: in a 4L stainless steel reactor with a jacket, an inert gas is introduced for replacement, and 2400g of cyclohexane, 290g of 2,4,6-tribromophenylallyl ether and 238mmol of THF are added to the polymerization reactor in sequence. The stirring speed is 580rpm, and when the temperature is raised to 78°C, 133mmol of n-butyllithium is added to react. When the conversion rate of 2,4,6-tribromophenylallyl ether monomer reaches 100%, 23g of 4-vinylbenzoic acid is added to the polymerization reactor for acidification reaction for 58min. After the reaction, the slurry is poured out, coagulated, washed, and vacuum dried to obtain macromolecular polar brominated ring-opening agent e (Mn is 2300, Mw / Mn is 1.95).

[0144] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 5.

[0145] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 5, except that a macromolecular polar brominated ring-opening agent was not added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer. Instead, a macromolecular polar brominated ring-opening agent e was added in an amount of 1.43 mol. Specifically, an epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in xylene to prepare a 4.7 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to a reaction vessel. The pH of the solution was adjusted to 4.6 with propionic anhydride. Then, 1.43 mol of macromolecular polar brominated ring-opening agent e and 0.09 mol of ZrCl4 were added. The mixture was heated to 148°C for 3.8 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested properties are shown in Table 1.

[0146] Comparative Example 6

[0147] (a) Preparation of macromolecular polar brominated ring-opening agents: Same as in Example 6.

[0148] (II) Preparation of epoxidized SIS thermoplastic elastomer: Same as in Example 6.

[0149] (III) Preparation of Low-Temperature Resistant, Brominated SIS Thermoplastic Elastomer: Other conditions were the same as in Example 6, except that the amount of macromolecular polar brominated ring-opening agent added during the preparation of the low-temperature resistant, brominated SIS thermoplastic elastomer was 0.5 mol. Specifically, epoxidized SIS thermoplastic elastomer containing 1 mol of epoxy groups was dissolved in chlorobenzene to prepare a 5.0 wt% epoxidized SIS thermoplastic elastomer solution, which was then added to the reaction vessel. When the pH of the solution was adjusted to 5.0 with butyric anhydride, 0.5 mol of macromolecular polar brominated ring-opening agent and 0.10 mol of ZrCl4 were added. The mixture was heated to 150°C for 4.0 hours for ring-opening reaction. The resulting mixture was precipitated with ethanol, washed, and dried to obtain the low-temperature resistant, brominated SIS thermoplastic elastomer. Sampling and Analysis: Standard samples were prepared, and the tested performance is shown in Table 1.

[0150] Table 1. Low-temperature resistance and properties of brominated SIS thermoplastic elastomers

[0151]

[0152]

[0153] As shown in Table 1, comparing Examples 1-8 with Comparative Examples 1-6, it is evident that the low-temperature resistant, brominated SIS thermoplastic elastomers prepared in Examples 1-8 exhibited a higher breakage rate at -20℃ than those in Comparative Examples 1-6. Furthermore, the glass transition temperatures of the low-temperature resistant, brominated SIS thermoplastic elastomers prepared in Examples 1-8 were lower than those in Comparative Examples 1-6, indicating that the macromolecular polar brominated ring-opening agent significantly improved the low-temperature resistance of SIS thermoplastic elastomers. Simultaneously, the tensile strength of the elastomers in Examples 1-8 was greater than that in Comparative Examples 1-6, demonstrating that the low-temperature resistant, brominated SIS thermoplastic elastomers maintained sufficient raw rubber tensile strength.

[0154] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a low-temperature resistant brominated SIS thermoplastic elastomer, characterized in that, Includes the following steps: Step 1 involves a block copolymerization reaction of tribromophenyl allyl ether and N-(hydroxyalkyl)acrylamide, followed by an acidification reaction with the addition of 4-vinylbenzoic acid to obtain a ring-opening agent. Step 2: The polyisoprene segments in the SIS thermoplastic elastomer undergo an epoxidation reaction to obtain epoxidized SIS; Step 3: The ring-opening agent is reacted with the epoxidized SIS to obtain a low-temperature resistant, flame-retardant brominated SIS thermoplastic elastomer. The mass ratio of the tribromophenyl allyl ether, N-(hydroxyalkyl)acrylamide and 4-vinylbenzoic acid is (40-60):(40-50):(3.0-5.0); the molar ratio of the ring-opening agent to the epoxy group in the epoxidized SIS is greater than or equal to 1.

2. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, Step 1 involves: subjecting the tribromophenyl allyl ether to a polymerization reaction; after the conversion rate of the tribromophenyl allyl ether monomer reaches 95%-100%, adding N-(hydroxyalkyl)acrylamide for further polymerization; after the conversion rate of the N-(hydroxyalkyl)acrylamide monomer reaches 95%, adding 4-vinylbenzoic acid for an acidification reaction to obtain a ring-opening agent; the tribromophenyl allyl ether has the following structure:

3. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 2, characterized in that, The polymerization reaction of the tribromophenyl allyl ether is carried out in a first solvent under the action of an initiator and a structure modifier; the initiator is a hydrocarbon monolithium compound, the structure modifier is a polar organic compound, and the first solvent is a hydrocarbon solvent; the mass ratio of the tribromophenyl allyl ether, N-(hydroxyalkyl)acrylamide, and 4-vinylbenzoic acid is (50-60):(40-50):(3.0-5.0); the molar ratio of the structure modifier to the initiator is (1.0-2.0):

1.

4. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The block copolymerization reaction is carried out at a temperature of 70–80°C, the acidification reaction is carried out at a temperature of 70–80°C, and the acidification reaction is carried out for a time of 30–40 min; N-(hydroxyalkyl)acrylamide is selected from one of N-(2-hydroxyethyl)acrylamide, N-(3-hydroxypropyl)acrylamide, and N-(4-hydroxybutyl)acrylamide.

5. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The ring-opening agent has the following structure: Formula I: Where R is a C1 to C3 straight-chain alkyl group; n and m are the number of repeating units, n≥1 and m≥1.

6. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 5, characterized in that, The ring-opening agent has a number-average molecular weight of 3000-4000 and a molecular weight distribution of 1.89-2.

18.

7. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The epoxidation reaction of polyisoprene segments in SIS thermoplastic elastomers is carried out in a second solvent under the action of organic acids and peroxides.

8. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 7, characterized in that, The organic acid is selected from at least one of formic acid, acetic acid, benzoic acid and salicylic acid, and the molar ratio of the organic acid to the SIS thermoplastic elastomer is (0.02-0.5):1; the peroxide is hydrogen peroxide and / or peracetic acid, and the molar ratio of the peroxide to the SIS thermoplastic elastomer is (0.1-1.5):1; the second solvent is selected from at least one of chlorobenzene, benzene, toluene, xylene, chloroform, acetone and ethylbenzene.

9. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The epoxy degree of the epoxidized SIS is 5% to 8%.

10. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The ring-opening reaction between the ring-opening agent and the epoxidized SIS is carried out under the action of a ring-opening catalyst, which is selected from at least one of zirconium tetrachloride, trifluoromethanesulfonic acid and imidazole; the molar ratio of the ring-opening catalyst to the epoxy group in the epoxidized SIS is (0.01-0.4):1; the molar ratio of the ring-opening agent to the epoxy group in the epoxidized SIS is (1.1-1.5):

1.

11. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 10, characterized in that, Before being mixed with the ring-opening agent, the epoxidized SIS is first mixed with an organic solvent, and the pH of the mixture is adjusted to 1-5; the molar ratio of epoxy groups, ring-opening agent and ring-opening catalyst in the epoxidized SIS is 100:(100-140):(3-9).

12. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 11, characterized in that, The pH of the mixture is adjusted to 1-5 using an acid anhydride, wherein the acid anhydride is selected from one or more of propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride, and octanoic anhydride.

13. The method for preparing the low-temperature resistant, brominated SIS thermoplastic elastomer according to claim 1, characterized in that, The ring-opening reaction temperature is 140–150°C, and the ring-opening reaction time is 3.0–4.0 hr.

14. The low-temperature resistant brominated SIS thermoplastic elastomer obtained by the preparation method according to any one of claims 1-13.

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