Process for halogenating copolymers

Abstract

The invention relates to the field of rubber preparation, and discloses an improved halogenated copolymer and a preparation method thereof.The halogenating method of the copolymer comprises the following steps that under the condition that ultrasonic and visible light illumination intensity is low, a copolymer, a halogenating agent and an optional substance I capable of absorbing hydrogen bromide are subjected to a contact reaction in a solvent, the halogenated copolymer is obtained. When the method is used for halogenating the copolymer, the side reaction in the copolymer and the solvent can be inhibited, the byproduct hydrogen bromide is effectively removed, the requirement on the purity of the solvent in industrial production is reduced, the production requirement can be met by using the conventional industrial solvent, and the production cost is reduced. Furthermore, the gel phenomenon can be avoided, impurities such as an initiator and an oxidizing agent are prevented from being introduced into the product, and the pure halogenated copolymer is obtained through simple and feasible process conditions and steps.

Description

Technical Field

[0001] The present invention relates to the field of rubber preparation, and specifically, to a method for halogenating a copolymer. Background Art

[0002] The copolymer of brominated isoolefin and p-alkylstyrene, especially the copolymer of brominated isobutene and p-methylstyrene BIMS, is a new type of fully saturated elastomer material with vulcanization activity and better comprehensive properties than bromobutyl rubber. Its bromination reaction mechanism is free radical bromination. The bromination reaction conditions of the copolymer of isobutene and p-methylstyrene are very harsh and are very sensitive to various impurities such as water, alcohol, acid, and base in the reaction system. Generally, the copolymer is dissolved in an alkane solvent and an organic radical initiator or an oxidant such as peroxide is added for solution bromination reaction, but there are various bromination side reactions. For example, there is a pair of competitive bromination reactions on the main chain of the copolymer of isobutene and p-methylstyrene, that is, the bromination of tertiary carbon hydrogen (3°H) and p-methyl hydrogen (1°H) on the benzene ring. The target reaction of copolymer bromination is the bromination of the p-methyl hydrogen (1°H) structure to form benzyl bromide. However, since the tertiary carbon hydrogen (3°H) is also relatively active, it is easily substituted by bromine and then transformed into a -C-Br group. The tertiary carbon bromide is extremely active and is prone to de-bromination reaction during drying at high temperatures such as above 100°C, resulting in cross-linking and discoloration of the product. And during the bromination reaction, generally, the bromine content in the target product reaches a peak point with the prolongation of the bromination time, and then gradually decreases with the increase of time. At this time, if the obtained product is dried and then dissolved in hexane, the gelation phenomenon can be clearly observed. The gel will reduce the strength of the product and affect its processing performance.

[0003] Therefore, it is necessary to provide a method for brominating a copolymer that can inhibit the occurrence of side reactions in the copolymer and the solvent and effectively reduce the occurrence of gelation during the bromination of the copolymer.

[0004] In addition, during the process of producing a halogenated polymer from a polymer and a halogenating agent, a solvent is an essential reaction medium. Through literature research, it is proved that hydrocarbon solvents can undergo halogenation reactions, especially chlorination and bromination reactions. For example, the section on alkane halogenation reactions in "Organic Chemistry" (Qian Xuhong et al., Chemical Industry Press, November 1999) indicates that alkanes do not react with halogens at room temperature and in the dark, but react under the conditions of light, heat, and free radical initiators. The halogenation reaction of alkanes is a free radical reaction. Among them, alkanes containing tertiary carbon hydrogen (3°H) structures have higher halogenation reaction activities. In industrial production, hydrocarbon solvents are usually used. For example, the purity of industrial n-hexane is 65%-85%, and the solvent usually contains other components, especially isomers of n-hexane, such as methylcyclopentane, 2-methylpentane, 3-methylpentane, etc., which are difficult to separate.

[0005] Therefore, in chemical production, in order to avoid the halogenation reaction of isomers in the solvent, it is usually necessary to select high-purity n-alkanes. For example, for the copolymer of iso-monoolefins and p-alkylstyrene, especially for the halogenation reaction of the copolymer of isobutene and p-methylstyrene in an alkane solvent, in order to avoid the halogenation reaction of the solvent, high-purity n-hexane or cyclohexane with a purity of more than 99% is required, which will lead to a substantial increase in production costs.

[0006] In addition, in the prior art, the reaction of polymers with halogenating agents is mostly carried out in the presence of organic radical initiators (such as azo compounds) and / or oxidants (such as peroxides), which introduces many impurities and has many side reactions.

[0007] Therefore, it is necessary to provide a halogenation method applicable to the copolymer of iso-monoolefins and p-alkylstyrene, so that when the copolymer is halogenated in a solvent, the occurrence of side reactions in the copolymer and the solvent can be inhibited, the by-product hydrogen halide can be effectively removed, the occurrence of gelation phenomenon can be avoided, and the requirement for the purity of the solvent in industrial production can be reduced. Using conventional industrial solvents can meet the production requirements and reduce production costs; it can avoid introducing impurities such as initiators and oxidants into the product, and obtain a pure halogenated polymer with simple, easy-to-implement and mild process conditions and steps. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects in the prior art that the gelation phenomenon is serious during the halogenation of the copolymer of iso-monoolefins and alkylstyrene, resulting in a high gelation rate of the target product, high requirements for the purity of the solvent, and low effective utilization rate of halogens, and to provide a halogenation method for the copolymer.

[0009] The halogenation method of the copolymer of the present invention includes the following steps:

[0010] Under the conditions of ultrasonic wave and visible light intensity lower than 0.05 lux, the copolymer, the halogenating agent and optionally the substance I capable of absorbing hydrogen halide are brought into contact reaction in a solvent to obtain a halogenated copolymer.

[0011] When the copolymer is halogenated by the method of the present invention, the occurrence of side reactions in the copolymer and the solvent can be inhibited, the by-product hydrogen halide can be effectively removed, and the requirement for the purity of the solvent in industrial production can be reduced. Using conventional industrial solvents can meet the production requirements and reduce production costs. Further, the present invention can avoid the occurrence of gelation phenomenon, avoid introducing impurities such as initiators and oxidants into the product, and obtain a pure halogenated copolymer with simple and easy-to-implement process conditions and steps. Detailed Embodiments

[0012] The endpoints and any values disclosed in this text for a range are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

[0013] To achieve the above object, a first aspect of the present invention provides a method for halogenating a copolymer, characterized in that the halogenation method comprises the following steps:

[0014] Under the conditions of ultrasound and visible light intensity lower than 0.05 lux, the copolymer, a halogenating agent, and optionally a substance I capable of absorbing hydrogen halide are brought into contact reaction in a solvent to obtain a halogenated copolymer.

[0015] In the present invention, the object of the present invention can be achieved as long as the halogenation is carried out under as dark conditions as possible. Preferably, the contact reaction is carried out under the condition of no visible light. A light-shielding object can be used to shield visible light, so that the method of the present invention is carried out under the condition of lower visible light intensity.

[0016] In the prior art, the reaction of halogenating agents is mostly carried out in the presence of organic radical initiators (such as azo compounds) and / or oxidants (such as peroxides), introducing many impurities and having many side reactions.

[0017] In the present invention, under the conditions of ultrasound and lower visible light intensity, the copolymer, a halogenating agent, and optionally a substance I capable of absorbing hydrogen halide are brought into contact reaction in a solvent, so that the copolymer is halogenated in the solvent. For example, when brominated, it can inhibit the occurrence of side reactions of impurities in the copolymer and the solvent during the halogenation reaction, and at the same time avoid introducing impurities such as initiators and oxidants into the halogenated copolymer product, and can obtain a pure halogenated copolymer with simple, easy-to-implement and mild process conditions and steps.

[0018] In the present invention, the total weight of the initiator and / or oxidant in the contact reaction system is lower than 0.015% of the weight of the copolymer. Preferably, the contact reaction does not contain an initiator and / or an oxidant.

[0019] The initiator or oxidant in the present invention is any common initiator or oxidant that can initiate a radical reaction. The initiator can be selected from azobisisobutyronitrile and / or azobisisoheptonitrile, and the oxidant can be selected from benzoyl peroxide and / or lauroyl peroxide.

[0020] According to the halogenation method provided by the present invention, in the present invention, the frequency of ultrasonic waves can be selected within a relatively wide range. For example, by controlling the frequency of ultrasonic waves at 20 KHz - 500 KHz, the occurrence of side reactions between the copolymer and the solvent can be inhibited, and the purpose of improving the effective utilization rate of the halogenating agent can be achieved. However, the higher the frequency of ultrasonic waves, the greater the energy consumption.

[0021] Furthermore, in order to improve the effective utilization rate of the halogenating agent and reduce energy consumption, preferably, the frequency of the ultrasonic waves is 20 KHz - 50 KHz.

[0022] In the present invention, in order to further reduce the generation of gel phenomenon during the halogenation of the copolymer of the present invention and reduce the gel rate of the target product, the optional substance I capable of absorbing hydrogen halide is selected from at least one of water, C 1-8 alcohols, carbonates, bicarbonates, and basic oxides.

[0023] In the present invention, the C 1-8 alcohols can be monohydric alcohols, dihydric alcohols, trihydric alcohols, or tetrahydric alcohols with a total carbon atom number of 1 - 8.

[0024] Preferably, the carbonate is selected from at least one of alkali metal carbonates or alkaline earth metal carbonates; the bicarbonate is selected from at least one of alkali metal bicarbonates or alkaline earth metal bicarbonates; the basic oxide is selected from at least one of alkali metal oxides or alkaline earth metal oxides.

[0025] Preferably, the alkali metal carbonate is selected from at least one of Li2CO3, Na2CO3, and K2CO3; the alkaline earth metal carbonate is selected from at least one of MgCO3, CaCO3, SrCO3, and BaCO3; the alkali metal bicarbonate is selected from NaHCO3 and / or KHCO3; the alkaline earth metal bicarbonate is selected from Mg(HCO3)2 and Ca(HCO3)2; the alkali metal oxide is selected from at least one of Li2O, Na2O, and K2O; the alkaline earth metal oxide is selected from at least one of MgO, CaO, and BaO;

[0026] Preferably, the substance I is NaHCO3 and / or KHCO3.

[0027] In the prior art, when a copolymer contacts a halogenating agent for a halogenation reaction, the purity requirement for the solvent is relatively high. However, other substances such as methylcyclopentane, 2 - methylpentane, and 3 - methylpentane are inevitably mixed into the alkane solvents sold in the prior art, and the separation is difficult. In the presence of a halogenating agent, the reaction between the isomerization impurities in the solvent and the copolymer forms a competitive reaction, significantly reducing the effective utilization rate of the halogenating agent. When the method of the present invention is used to halogenate the copolymer, a relatively high effective utilization rate of the halogenating agent can still be achieved under the condition of relatively low solvent purity.

[0028] According to the halogenation method provided by the present invention, the molar ratio of the dosage of the substance I to the halogenating agent is (0.1 - 2):1, preferably (0.2 - 1.5):1, and more preferably (0.25 - 1):1.

[0029] In the prior art, when the copolymer is contacted with the halogenating agent for the halogenation reaction, the purity requirement for the solvent is relatively high. However, other substances are inevitably mixed into the alkane solvents sold in the prior art, such as methylcyclopentane, 2-methylpentane, and 3-methylpentane, etc., and the separation is difficult. In the presence of the halogenating agent, the reaction between the isomerization impurities in the solvent and the copolymer forms a competitive reaction, significantly reducing the effective utilization rate of the halogenating agent. When the copolymer is halogenated by the method of the present invention, a high effective utilization rate of the halogenating agent can still be achieved under the condition of relatively low solvent purity. Therefore, according to the present invention, the purity of the solvent ≥ 50 wt%, preferably, the purity of the solvent ≥ 60 wt%, and preferably ≤ 85 wt%.

[0030] According to the present invention, the solvent is selected from at least one of straight-chain normal alkanes of C4 - C8 and cycloalkanes of C4 - C8; preferably, the solvent is n-hexane.

[0031] According to the present invention, the conditions of the contact reaction include: the ultrasonic power is 100 - 600 mW, the reaction temperature is 5 - 30 °C, and the reaction time is 10 - 60 min.

[0032] Furthermore, in order to further inhibit the occurrence of side reactions in the copolymer and the solvent and improve the effective utilization rate of the halogenating agent, preferably, the conditions of the contact reaction include: the ultrasonic power is 150 - 350 mW, the reaction temperature is 10 - 25 °C, and the reaction time is 20 - 40 min.

[0033] According to the present invention, the copolymer is a copolymer of C4 - C 12 iso-monoolefins and C9 - C 15 alkylstyrenes, preferably a copolymer of C4 - C7 iso-monoolefins and C9 - C 12 alkylstyrenes, and the C9 - C 15 alkylstyrene monomers are selected from at least one of p-methylstyrene, p-ethylstyrene, and p-isobutylstyrene, and more preferably a copolymer of isobutene and / or isopentene and p-methylstyrene.

[0034] In order to further verify that methylcyclopentane, 2-methylpentane and 3-methylpentane do not undergo substitution reaction in the substitution method provided by the present invention, and the alkyl hydrogen on the phenyl group has high selectivity in the substitution method provided by the present invention, the inventors used other compounds with similar structures for testing. Under the conditions of low ultrasound and visible light intensity and room temperature, the inventors studied the bromination reaction process of p-xylene with liquid bromine. Specifically, under the same conditions, an equal amount of liquid bromine was added to methylcyclopentane, 2-methylpentane, 3-methylpentane and p-xylene, respectively, and the bromination reaction was carried out under the same ultrasound and no visible light conditions and room temperature. The fading of the orange color in the solution indicates the end of the reaction, that is, the complete reaction of the bromine element.

[0035] The research results show that when the bromination contact reaction is carried out under the conditions of low ultrasound and visible light intensity and room temperature, methylcyclopentane, 2-methylpentane and 3-methylpentane do not undergo bromination reaction, while p-xylene undergoes bromination reaction on the methyl group, and the reaction is relatively fast.

[0036] According to the present invention, based on the total weight of the copolymer, the content of the structural unit derived from alkylstyrene in the copolymer is 0.5-90 wt %, preferably 1-50 wt %.

[0037] In a specific embodiment of the present invention, the copolymer is a copolymer of isobutylene and p-methylstyrene, and based on the total weight of the copolymer, the content of the structural unit from p-methylstyrene in the copolymer is 3-20% by weight, and the rest is the structural unit from isobutylene. The halogenation method provided by the present invention is more suitable for the above copolymer, and can further improve the effective utilization rate of the halogenating agent. In the present invention, the effective utilization rate of the halogenating agent refers to the molar amount of the halogenating agent introduced into the p-methyl hydrogen (1°H) position of the copolymer in the halogenation reaction to form the benzyl halide The ratio of the molar amount of the halogenating agent participating in the halogenation reaction.

[0038] According to the present invention, the weight average molecular weight of the copolymer is preferably 100,000-1,000,000.

[0039] According to the present invention, the halogenating agent is preferably a halogen element, more preferably liquid bromine.

[0040] In the present invention, in order to further improve the effective utilization rate of the halogenating agent, preferably, relative to 100 parts by weight of the solvent, the amount of the copolymer is 1-20 parts by weight, and the amount of the halogenating agent is 0.08-1.2 parts by weight.

[0041] In the present invention, more preferably, relative to 100 parts by weight of the solvent, the amount of the copolymer is 5-15 parts by weight, and the amount of the halogenating agent is 0.2-0.5 parts by weight.

[0042] The present invention will be described in detail below by way of examples.

[0043] In the following examples, unless otherwise specified, the raw materials can be obtained commercially; 85% n-hexane is selected from Yanshan Juhua brand, with a purity of 85 wt%, among which the content of impurity methylcyclopentane is 7.70 wt%, the content of impurity 3-methylpentane is 5.52 wt%, and the content of impurity 2-methylpentane is 0.34 wt%; 60% n-hexane is selected from Yanshan Juhua brand, with a purity of 60 wt%, among which the content of impurity methylcyclopentane is 10.31 wt%, the content of impurity 3-methylpentane is 18.11 wt%, and the content of impurity 2-methylpentane is 4.34 wt%. Liquid bromine: analytical pure, ≥99 wt%, Beijing Yili Fine Chemicals Co., Ltd.; azobisisobutyronitrile (ABVN): analytical pure, ≥99 wt%, J&K CHEMIC; sodium bicarbonate: analytical pure, ≥99 wt%, Beijing Chemical Plant.

[0044] The effective utilization rate of bromine is determined by the following method: The degree of bromination of the copolymer is measured using a Bruker AVANCE400 nuclear magnetic resonance spectrometer (400 Hz) from Switzerland, with a magnetic field strength of 9.40 Tesla, using CDCl3 as the solvent and TMS as the internal standard. The target product is a copolymer in which the hydrogen on the alkyl group in the alkylstyrene structural unit of the isomonoolefin and alkylstyrene copolymer is replaced by a bromine atom.

[0045] The effective utilization rate of bromine % = the number of moles of bromine in the target product / the number of moles of bromine participating in the reaction × 100%. The density of liquid bromine is 3.119 g / mL.

[0046] The gel fraction test method is as follows: Take W2 g of the brominated target product and cut it into pieces. Wrap the crushed sample in a cylinder folded from a filter paper with a mass of W1 g and place it in a Soxhlet extractor. Use tetrahydrofuran as the extractant and reflux for 8 h. Then take out the filter paper cylinder, dry it, and weigh it. At this time, the mass of the remaining sample and the filter paper is W3 g. Then the gel fraction % = (W3 - W1) / W2 × 100%.

[0047] Example 1

[0048] Dissolve 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of this copolymer is 500,000, and based on the total weight of the copolymer, the content of the structural unit from p-methylstyrene is 12% by weight) in 225 g of 85 wt% n-hexane. Then add 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate. After mixing evenly, carry out a contact reaction under ultrasonic waves with a frequency of 20 KHz and a power of 300 W and in the absence of visible light irradiation. The reaction temperature is 25 °C and the reaction time is 30 min.

[0049] The calculated effective utilization rate of bromine is 81%, and no gel phenomenon occurs.

[0050] Example 2

[0051] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate were added. After mixing evenly, a contact reaction was carried out under ultrasonic waves with a frequency of 50 KHz and a power of 300 W and in the absence of visible light irradiation. The reaction temperature was 25 °C, and the reaction time was 30 min.

[0052] The calculated effective utilization rate of bromine is 78%, and no gel phenomenon occurs.

[0053] Example 3

[0054] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate were added. After mixing evenly, a contact reaction was carried out under ultrasonic waves with a frequency of 30 KHz and a power of 300 W and in the absence of visible light irradiation. The reaction temperature was 25 °C, and the reaction time was 30 min.

[0055] The calculated effective utilization rate of bromine is 80%, and no gel phenomenon occurs.

[0056] Example 4

[0057] This example was carried out in a similar manner to Example 1, except that:

[0058] In this example, the contact reaction was carried out under the action of ultrasonic waves at 100 KHz.

[0059] The calculated effective utilization rates of bromine are 76% respectively, and no gel phenomenon occurs.

[0060] Example 5

[0061] This example was carried out in a similar manner to Example 1, except that:

[0062] In this example, the contact reaction was carried out under the action of ultrasonic waves at 200 KHz.

[0063] The calculated effective utilization rates of bromine are 74% respectively, and no gel phenomenon occurs.

[0064] Example 6

[0065] This example is carried out in a similar manner to Example 1, except that:

[0066] In this example, the contact reaction is carried out under the action of 500 KHz ultrasound.

[0067] The calculated effective utilization rate of bromine is 73% respectively, and no gel phenomenon occurs.

[0068] Example 7

[0069] This example is carried out in a similar manner to Example 1, except that:

[0070] In this example, 85 wt% n-hexane is replaced with an equal mass of 60 wt% n-hexane.

[0071] The calculated effective utilization rate of bromine is 72%, and no gel phenomenon occurs.

[0072] Example 8

[0073] This example is carried out in a similar manner to Example 1, except that:

[0074] In this example, 1.06 g of liquid bromine is added, and sodium bicarbonate is added according to the molar ratio of sodium bicarbonate to liquid bromine of 0.1:1.

[0075] The calculated effective utilization rate of bromine is 76%, and the gel rate is 20%.

[0076] Example 9

[0077] This example is carried out in a similar manner to Example 1, except that:

[0078] In this example, 1.06 g of liquid bromine is added, and sodium bicarbonate is added according to the molar ratio of sodium bicarbonate to liquid bromine of 0.2:1.

[0079] The calculated effective utilization rate of bromine is 73%, and the gel rate is 8%.

[0080] Example 10

[0081] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of this copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units from p-methylstyrene in the copolymer is 12% by weight) is dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate are added. After mixing evenly, the contact reaction is carried out under ultrasound with a frequency of 20 KHz and a power of 300 W and in the absence of visible light irradiation. The reaction temperature is 25 °C, and the reaction time is 20 min.

[0082] The calculated effective utilization rate of bromine is 79%, and no gel phenomenon occurs.

[0083] Example 11

[0084] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units derived from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate were added. After mixing evenly, the contact reaction was carried out under ultrasonic waves with a frequency of 20 KHz and a power of 200 W and without visible light irradiation. The reaction temperature was 25 °C, and the reaction time was 30 min.

[0085] The calculated effective utilization rate of bromine is 77%, and no gel phenomenon occurs.

[0086] Example 12

[0087] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units derived from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) was added without adding sodium bicarbonate. After mixing evenly, the contact reaction was carried out under ultrasonic waves with a frequency of 30 KHz and a power of 300 W and without visible light irradiation. The reaction temperature was 25 °C, and the reaction time was 30 min.

[0088] The calculated effective utilization rate of bromine is 78%, and the gel rate is 35%.

[0089] Comparative Example 1

[0090] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of structural units derived from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane, then 0.34 mL of liquid bromine (1.06 g) and 0.14 g of sodium bicarbonate were added. After mixing evenly, it was irradiated with a tungsten lamp with a light power of 150 W, and the contact reaction was carried out without ultrasonic action. The reaction time was 2 min, and the reaction temperature was 25 °C.

[0091] The calculated effective utilization rate of bromine is 62%, and no gel phenomenon occurs.

[0092] Comparative Example 2

[0093] 25 g of a copolymer formed from isobutene monomer and p-methylstyrene monomer (the weight-average molecular weight of the copolymer is 500,000, and based on the total weight of the copolymer, the content of the structural unit derived from p-methylstyrene in the copolymer is 12% by weight) was dissolved in 225 g of 85 wt% n-hexane. Then, 10 g of a n-hexane solution containing 0.4% by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) and 0.34 mL of liquid bromine (1.06 g) were added successively. Without ultrasound and without adding sodium bicarbonate, after mixing evenly, the reaction was carried out for 8 min at a reaction temperature of 56 °C.

[0094] The calculated effective utilization rate of bromine was 38%, and the gel fraction was 30%.

[0095] From the above results, it can be seen that by carrying out the contact reaction under the conditions of 20 KHz - 400 KHz ultrasound, without visible light irradiation, and in the presence of a substance capable of absorbing hydrogen bromide, the occurrence of side reactions in the copolymer and the solvent can be inhibited, the by-product hydrogen bromide can be effectively removed, and the occurrence of gelation can be avoided. And even when the solvent purity is 60 wt%, the effective utilization rate of bromine can still reach 72%, greatly reducing the requirement for solvent purity, saving energy consumption, and reducing production costs. The conditions for initiating the halogenation reaction in the comparative example were light irradiation and an initiator. Under these two initiation methods, only under the temperature and time conditions provided in the comparative example can the reaction proceed completely. At the same time, the present invention can avoid introducing impurities such as initiators and oxidants into the product, and can obtain the target halogenated copolymer simply, easily, mildly, and quickly.

[0096] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for halogenating a copolymer, characterized in that, The halogenation method comprises the following steps: Under the conditions of ultrasound and visible light intensity lower than 0.05 lux, a copolymer, a halogenating agent and optionally a substance I capable of absorbing hydrogen halide are brought into contact reaction in a solvent to obtain a halogenated copolymer; Preferably, the contact reaction is carried out under the condition of no visible light.

2. The halogenation method according to claim 1, wherein, The total weight of the initiator and / or oxidant in the contact reaction system is lower than 0.015% of the weight of the copolymer; Preferably, the contact reaction system does not contain an initiator and / or an oxidant.

3. The halogenation method according to claim 1 or 2, wherein The frequency of the ultrasound is 20 KHz - 500 KHz, preferably 20 KHz - 50 KHz.

4. The halogenation method according to any one of claims 1-3, wherein, The substance I is selected from at least one of water, an alcohol of C 1-8 , a carbonate, a bicarbonate, and a basic oxide; Preferably, the carbonate is selected from at least one of alkali metal carbonates and alkaline earth metal carbonates; the bicarbonate is selected from at least one of alkali metal bicarbonates and alkaline earth metal bicarbonates; the basic oxide is selected from at least one of alkali metal oxides and alkaline earth metal oxides; Preferably, the alkali metal carbonate is selected from at least one of Li2CO3, Na2CO3 and K2CO3; the alkaline earth metal carbonate is selected from at least one of MgCO3, CaCO3, SrCO3 and BaCO3; the alkali metal bicarbonate is selected from NaHCO3 and / or KHCO3; the alkaline earth metal bicarbonate is selected from Mg(HCO3)2 and / or Ca(HCO3)2; the alkali metal oxide is selected from at least one of Li2O, Na2O and K2O; the alkaline earth metal oxide is selected from at least one of MgO, CaO and BaO; Preferably, the substance I is NaHCO3 and / or KHCO3.

5. The halogenation method according to any one of claims 1-4, wherein, The molar ratio of the amount of the substance I to the halogenating agent is (0.1 - 2):1, preferably (0.2 - 1.5):1, more preferably (0.25 - 1):

1.

6. The halogenation method according to any one of claims 1-5, wherein, The purity of the solvent ≥ 50 wt%; preferably, the purity of the solvent ≥ 60 wt%, more preferably ≤ 85 wt%.

7. The halogenation method according to any one of claims 1-6, wherein, The power of the ultrasound is 100 W - 600 W, preferably 150 W - 350 W.

8. The halogenation method according to any one of claims 1-7, wherein, The solvent is selected from at least one of straight-chain normal alkanes having 4 - 8 carbon atoms and cycloalkanes having 4 - 8 carbon atoms; preferably, the solvent is n-hexane.

9. The halogenation method according to any one of claims 1-8, wherein, The conditions of the contact reaction include: the reaction temperature is 5 - 30 °C, and the reaction time is 10 - 60 min; Preferably, the reaction temperature is 10 - 25 °C, and the reaction time is 20 - 40 min.

10. The halogenation method according to any one of claims 1-9, wherein, The copolymer is a C4-C 12 copolymer of isoolefin and C9-C 15 alkylstyrene, preferably a copolymer of C4-C7 isoolefin and C9-C 12 alkylstyrene, and the C9-C 15 alkylstyrene is selected from at least one of p-methylstyrene, p-ethylstyrene, and p-isobutylstyrene. More preferably, the copolymer is a copolymer of isobutene and p-methylstyrene, and / or a copolymer of isopentene and p-methylstyrene; Preferably, based on the total weight of the copolymer, the content of the structural unit derived from alkylstyrene in the copolymer is 0.5 - 90% by weight, preferably 1 - 50% by weight; Preferably, the weight-average molecular weight of the copolymer is 100,000 - 1,000,000.

11. The halogenation method according to any one of claims 1-10, wherein, The halogenating agent is a halogen element, preferably liquid bromine.

12. The halogenation method according to any one of claims 1-11, wherein, Relative to 100 parts by weight of the solvent, the amount of the copolymer used is 1 - 20 parts by weight, and the amount of the halogenating agent used is 0.08 - 1.2 parts by weight; Preferably, relative to 100 parts by weight of the solvent, the amount of the copolymer used is 5 - 15 parts by weight, and the amount of the halogenating agent used is 0.2 - 0.5 parts by weight.