Low-cis polybutadiene rubber and preparation method thereof, and HIPS resin and preparation method thereof

Abstract

This invention relates to the field of synthetic rubber and modified resins, and discloses a low-cis polybutadiene rubber and its preparation method, as well as a HIPS resin and its preparation method. The low-cis polybutadiene rubber exhibits a three-peaked number-average molecular weight distribution: a first peak with a number-average molecular weight of 310,000-360,000 g / mol, a second peak with a number-average molecular weight of 120,000-150,000 g / mol, and a third peak with a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%; the low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber. The low-cis polybutadiene rubber provided by this invention is used as a toughening agent in the preparation of HIPS resin. Due to the synergistic effect between rubbers of different particle sizes, the HIPS resin exhibits high surface gloss and high impact strength.

Description

Technical Field

[0001] This invention relates to the field of synthetic rubber and modified resins, specifically to a low-cis polybutadiene rubber and its preparation method, and a HIPS resin and its preparation method. Background Technology

[0002] In the preparation of HIPS resin (high impact polystyrene), commonly used rubbers as toughening agents include low-cis polybutadiene rubber, high-cis polybutadiene rubber, butadiene-isoprene copolymer, solution-polymerized styrene-butadiene rubber, and styrene-butadiene-styrene copolymer, with low-cis polybutadiene rubber and high-cis polybutadiene rubber being the most optimal. For low-temperature toughening resins, low-cis polybutadiene rubber and its derivative, block styrene-butadiene rubber, are generally used for toughening. However, the molecular weight and distribution of the toughening rubber have a significant impact on the impact resistance of continuous bulk HIPS resin. Generally, if the rubber molecular weight is too small, the toughening effect is poor; if the rubber molecular weight is too large, the HIPS resin has poor gloss. In selecting toughening agents, it is necessary to match rubbers of different particle sizes to achieve a synergistic effect and balance between gloss and impact resistance, but this makes the polymerization process more complex.

[0003] By using coupling agents with different functional groups to form a compound, functional groups with different particle sizes can be obtained. However, the reactivity of the coupling agents in the compound is inconsistent, resulting in poor stability of the toughening agent. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that existing aromatic vinyl resin toughening agents are difficult to achieve multi-level particle size matching, and to provide a low-cis polybutadiene rubber and its preparation method and a HIPS resin and its preparation method. The low-cis polybutadiene rubber has a three-peak molecular weight distribution, which makes the rubber exhibit a multi-level particle size distribution. When used as a toughening agent for HIPS resin, the resulting HIPS resin has the characteristics of high gloss and high impact resistance.

[0005] To achieve the above objectives, the first aspect of the present invention provides a low-cis polybutadiene rubber, wherein the number-average molecular weight of the low-cis polybutadiene rubber exhibits a three-peak distribution, with a first peak number-average molecular weight of 310,000-360,000 g / mol, a second peak number-average molecular weight of 120,000-150,000 g / mol, and a third peak number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%.

[0006] The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

[0007] A second aspect of the present invention provides a method for preparing low-cis polybutadiene rubber, wherein the method includes the following steps:

[0008] Low-cis polybutadiene rubber solution BR1 and low-cis polybutadiene rubber solution BR2 are mixed, and the solvent is removed to obtain the low-cis polybutadiene rubber.

[0009] The amounts of the low-cis polybutadiene rubber solution BR1 and the low-cis polybutadiene rubber solution BR2 are such that the number-average molecular weight of the obtained low-cis polybutadiene rubber exhibits a three-peak distribution: the first peak has a number-average molecular weight of 310,000-360,000 g / mol, the second peak has a number-average molecular weight of 120,000-150,000 g / mol, and the third peak has a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%.

[0010] The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

[0011] A third aspect of the present invention provides a method for preparing HIPS resin, the method comprising: polymerizing styrene and a toughening agent in a benzene-based solvent in the presence of a free radical initiator; wherein the toughening agent contains the aforementioned low-cis polybutadiene rubber; wherein the benzene-based solvent is selected from at least one of unsubstituted or C1-C4 alkyl-substituted benzenes.

[0012] A fourth aspect of the present invention provides a HIPS resin prepared by the above method.

[0013] Through the above technical solutions, the low-cis polybutadiene rubber and its preparation method and the HIPS resin and its preparation method provided by the present invention achieve the following beneficial effects.

[0014] The low-cis polybutadiene rubber provided by this invention has a three-peaked number-average molecular weight distribution, with each peak having a specific peak area. This allows the low-cis polybutadiene rubber of this invention to exhibit a multi-level particle size distribution, resulting in rubber with suitable solution viscosity, which is beneficial for improving resin gloss and impact strength. When low-cis polybutadiene rubber is used as a toughening agent in the preparation of HIPS resin, the synergistic effect between rubbers of different particle sizes gives the HIPS resin the characteristics of high surface gloss and high impact strength.

[0015] This invention mixes two low-cis polybutadiene rubber solutions to make the number-average molecular weight of the low-cis polybutadiene rubber exhibit a three-peak distribution, and the number-average molecular weight and peak area of ​​each peak meet the requirements of the low-cis polybutadiene rubber of this invention. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of this invention provides a low-cis polybutadiene rubber, wherein the number-average molecular weight of the low-cis polybutadiene rubber exhibits a three-peak distribution: a first peak with a number-average molecular weight of 310,000-360,000 g / mol, a second peak with a number-average molecular weight of 120,000-150,000 g / mol, and a third peak with a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%.

[0018] The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

[0019] In this invention, the low-cis polybutadiene rubber has a three-peaked number-average molecular weight distribution, with each peak having a specific peak area. This three-peaked distribution of number-average molecular weight and peak area allows the low-cis polybutadiene rubber of this invention to exhibit a multi-level particle size distribution, resulting in rubber with suitable solution viscosity, which is beneficial for improving the resin's gloss. Using low-cis polybutadiene rubber as a toughening agent in the preparation of HIPS resin, the synergistic effect between rubbers of different particle sizes gives the HIPS resin the characteristics of high surface gloss and high impact strength.

[0020] In this invention, the low-cis polybutadiene rubber refers to polybutadiene rubber with a cis-1,4-structure content of 30wt%-40wt%.

[0021] In this invention, the low-cis polybutadiene rubber can be a single type of low-cis polybutadiene rubber or a mixture of multiple low-cis polybutadiene rubbers, as long as the number-average molecular weight of the single type of low-cis polybutadiene rubber or the mixture of multiple low-cis polybutadiene rubbers exhibits a three-peak distribution, and the number-average molecular weight and peak area of ​​each peak meet the requirements of this invention.

[0022] According to the present invention, preferably, in the low cis polybutadiene rubber, the first peak number-average molecular weight is 320,000-355,000 g / mol, more preferably 330,000-350,000 g / mol; and the peak area of ​​the first peak is 25%-40%, more preferably 27%-36%.

[0023] According to the present invention, preferably, in the low cis polybutadiene rubber, the number-average molecular weight of the second peak is 125,000-145,000 g / mol, more preferably 130,000-140,000 g / mol; and the peak area of ​​the second peak is 57%-75%, more preferably 62%-72%.

[0024] According to the present invention, preferably, in the low cis polybutadiene rubber, the number-average molecular weight of the third peak is 37,000-46,000 g / mol, more preferably 38,000-45,000 g / mol; and the peak area of ​​the third peak is 0.6%-5%, more preferably 0.8%-3%.

[0025] According to the present invention, preferably, the viscosity of the low-cis polybutadiene rubber in a 5 wt% styrene solution at 25°C is 80-130 cp. Controlling the solution viscosity within the above range is beneficial for obtaining HIPS resin with higher gloss and stronger impact resistance.

[0026] Furthermore, the viscosity of the low-cis polybutadiene rubber in a 5wt% styrene solution at 25°C is 90-110 cp.

[0027] According to the present invention, the Mooney viscosity ML (1+4min, 100°C) of the low cis polybutadiene rubber is 40-55. When the Mooney viscosity of the rubber meets the above range, the low cis polybutadiene rubber has superior processing properties and is easier to process and mold.

[0028] According to the present invention, the gel content of the low-cis polybutadiene rubber is not higher than 150 ppm. The lower the gel content, the better it is to obtain HIPS resin with excellent performance.

[0029] Furthermore, the gel content of the low-cis polybutadiene rubber is not higher than 100 ppm.

[0030] Furthermore, the gel content of the low-cis polybutadiene rubber is not higher than 80 ppm.

[0031] According to the present invention, the vinyl content of the low-cis polybutadiene rubber is 8wt%-20wt%.

[0032] In this invention, the vinyl content can also be referred to as the content of 1,2-structural units, which refers to the content of structural units formed by butadiene through 1,2-polymerization. When the vinyl content meets the scope of this invention, the grafting reaction of continuous bulk HIPS resin and the appropriate crosslinking in the later stages can be guaranteed.

[0033] Furthermore, the vinyl content of the low-cis polybutadiene rubber is 10wt%-16wt%.

[0034] According to the present invention, low cis polybutadiene rubber can achieve a lower color intensity. Preferably, the color intensity of the 5 wt% styrene solution of the low cis polybutadiene rubber is less than or equal to 15 APHA, more preferably less than or equal to 8 APHA, and more preferably less than or equal to 5 APHA.

[0035] A second aspect of the present invention provides a method for preparing low-cis polybutadiene rubber, wherein the method includes the following steps:

[0036] Low-cis polybutadiene rubber solution BR1 and low-cis polybutadiene rubber solution BR2 are mixed, and the solvent is removed to obtain the low-cis polybutadiene rubber.

[0037] The amounts of the low-cis polybutadiene rubber solution BR1 and the low-cis polybutadiene rubber solution BR2 are such that the number-average molecular weight of the obtained low-cis polybutadiene rubber exhibits a three-peak distribution: the first peak has a number-average molecular weight of 310,000-360,000 g / mol, the second peak has a number-average molecular weight of 120,000-150,000 g / mol, and the third peak has a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%.

[0038] The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

[0039] In this invention, two low-cis polybutadiene rubber solutions are mixed to make the number-average molecular weight of the low-cis polybutadiene rubber exhibit a three-peak distribution, and the number-average molecular weight and peak area of ​​each peak meet the requirements of the low-cis polybutadiene rubber of this invention.

[0040] According to the present invention, the preparation method of the low-cis polybutadiene rubber solution BR1 includes the following steps:

[0041] Under anionic polymerization conditions, butadiene 1 is subjected to a first polymerization in an organic solvent in the presence of a first organolithium initiator and a first structure modifier to obtain a polymerization solution 1; the polymerization solution 1 is contacted with a first coupling agent to carry out a first coupling reaction, and then a first terminator is added to obtain a low-cis polybutadiene rubber solution BR1.

[0042] According to the present invention, the preparation method of the low-cis polybutadiene rubber solution BR2 includes the following steps:

[0043] Under anionic polymerization conditions, butadiene 2 is subjected to a second polymerization in an organic solvent in the presence of a second organolithium initiator and a second structure modifier to obtain a polymerization solution 2; the polymerization solution 2 is then contacted with a second coupling agent to carry out a second coupling reaction, and a second terminator is added to obtain a low-cis polybutadiene rubber solution BR2.

[0044] According to the present invention, in the preparation process of the low-cis polybutadiene rubber solution BR1, the content of butadiene 1 is 10wt%-20wt%, preferably 10wt%-16wt%, based on the total weight of the organic solvent and butadiene 1. In the preparation process of the low-cis polybutadiene rubber solution BR2, the content of butadiene 2 is 10wt%-20wt%, preferably 10wt%-16wt%, based on the total weight of the organic solvent and butadiene 2. In the present invention, the content of butadiene 1 and the content of butadiene 2 can be the same or different.

[0045] In this invention, the organic solvents used in the preparation of BR1 and BR2 can be the same or different. These organic solvents can be various organic solvents conventionally used in the art. Preferably, each organic solvent is independently one or more of alkane solvents and cycloalkane solvents. The alkane solvents are preferably one or more of C4-C8 alkane solvents, more preferably one or more of n-pentane, n-hexane, n-heptane, and isooctane. The cycloalkane solvents are preferably one or more of C4-C8 cycloalkane solvents, more preferably one or more of cyclopentane, cyclohexane, and cycloheptane.

[0046] In a preferred embodiment of the present invention, the organic solvents are each independently selected from a combination of cyclohexane and hexane in a weight ratio of 1:0.1-0.5.

[0047] According to the present invention, there is no particular limitation on the first and second organolithium initiators, which may be the same or different. Various organolithium initiators conventionally used in the preparation of polybutadiene rubber in the art can be used. Preferably, the organolithium initiator is a compound represented by Formula I.

[0048] R 1Li-type I

[0049] Among them, R 1 Selected from C1-C 10 The alkyl group; more preferably, the organolithium initiator is one or more selected from n-butyllithium, sec-butyllithium, isobutyllithium, and tert-butyllithium, more preferably n-butyllithium and / or sec-butyllithium, and even more preferably n-butyllithium. The organolithium initiator is added to the polymerization system in solution form, and the solvent for the organolithium initiator can be one or more selected from hexane, cyclohexane, heptane, etc., with a concentration preferably 0.1-1 mol / L.

[0050] The amounts of the first and second organolithium initiators of this invention can be rationally selected based on the amount of monomer and the desired molecular weight of the low-cis polybutadiene rubber, and their amounts can vary within a wide range. Preferably, the molar ratio of butadiene 1 to the first organolithium initiator is 650-900:1, more preferably 680-850:1, and even more preferably 700-830:1; the molar ratio of butadiene 2 to the second organolithium initiator is 2200-2800:1, more preferably 2300-2700:1, and even more preferably 2400-2600:1.

[0051] In this invention, the actual amount of the first and second organolithium initiators is the amount of effective organolithium initiators, which can be understood as the actual amount not including the amount of organolithium initiators used for sterilization.

[0052] In this invention, the anionic solution polymerization reaction is carried out in the presence of a structure modifier. The first and second structure modifiers can be conventionally selected in the art, and the first and second structure modifiers can be the same or different. Preferably, the structure modifier is one or more of ether-based and amine-based structure modifiers.

[0053] Preferably, the ether compound structure modifier is one or more of aliphatic monoethers, aliphatic polyethers, aromatic ethers, and cyclic ethers.

[0054] More preferably, the aliphatic monoether is one or more of aliphatic symmetrical monoether and aliphatic asymmetric monoether, the aliphatic symmetrical monoether is one or more of methyl ether, diethyl ether, propyl ether and butyl ether, and the aliphatic asymmetric monoether is methyl ethyl ether.

[0055] More preferably, the aliphatic polyether is one or more of aliphatic symmetrical polyether and aliphatic asymmetric polyether, the aliphatic symmetrical polyether is one or more of ethylene glycol diC1-C4 alkyl ether, diethylene glycol diC1-C4 alkyl ether and diethylene glycol diC1-C4 alkyl ether, preferably one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, and the aliphatic asymmetric polyether is ethylene glycol methyl ethyl ether and / or diethylene glycol methyl ethyl ether.

[0056] Preferably, the aromatic ether is anisole and / or diphenyl ether.

[0057] Preferably, the cyclic ether is one or more of tetrahydrofuran, tetrahydrofurfuryl C1-C4 alkyl ether, and 1,4-dioxane, and more preferably one or more of tetrahydrofuran, tetrahydrofurfuryl methyl ether, tetrahydrofurfuryl ethyl ether, tetrahydrofurfuryl propyl ether, tetrahydrofurfuryl isopropyl ether, tetrahydrofurfuryl butyl ether, and 1,4-dioxane.

[0058] Preferably, the amine compound structure modifier is one or more of N,N,N',N'-tetramethylethylenediamine, N,N-dimethyltetrahydrofurfurylamine, triethylamine, and tripropylamine.

[0059] In a preferred embodiment of the present invention, the structure modifier is one or more of tetrahydrofuran, tetrahydrofurfuryl methyl ether, tetrahydrofurfuryl ethyl ether, tetrahydrofurfuryl propyl ether, tetrahydrofurfuryl isopropyl ether, tetrahydrofurfuryl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, more preferably one or more of tetrahydrofurfuryl methyl ether, tetrahydrofurfuryl ethyl ether, and tetrahydrofurfuryl propyl ether, and particularly preferably tetrahydrofurfuryl ethyl ether.

[0060] In this invention, the molar ratio of the first structure modifier to the first organolithium initiator is 0.02-2:1; the molar ratio of the second structure modifier to the second organolithium initiator is also 0.02-2:1. When the amount of structure modifier is within the range specified in this invention, the vinyl content of the prepared low-cis polybutadiene rubber is within the range specified in this invention, while the reaction rate is increased.

[0061] According to the present invention, in the preparation of BR1 and BR2, the anionic solution polymerization reaction results in a butadiene conversion rate of 98% or higher. Preferably, the conditions for the first polymerization include: a temperature of 0-100°C, more preferably 40-100°C, and even more preferably 50-100°C; and a time of 20-100 min, preferably 30-60 min. Preferably, the conditions for the second polymerization include: a temperature of 0-100°C, more preferably 40-100°C, and even more preferably 50-100°C; and a time of 20-100 min, preferably 30-60 min.

[0062] In this invention, the temperature of the first polymerization includes the initiation temperature and the maximum temperature of the first polymerization; preferably, the difference between the maximum temperature and the initiation temperature of the first polymerization is 35-50°C. The temperature of the second polymerization includes the initiation temperature and the maximum temperature of the second polymerization; preferably, the difference between the maximum temperature and the initiation temperature of the second polymerization is 35-50°C.

[0063] According to the present invention, the first coupling agent and the second coupling agent are each independently a silane coupling agent, preferably one or more of silicon tetrachloride, silicon tetrabromide, and tin tetrachloride, and more preferably silicon tetrachloride. Silicon tetrachloride allows for more precise control of the coupling reaction, resulting in higher stability and repeatability of the coupling reaction.

[0064] According to the present invention, in the process of preparing BR1 and BR2, the amount of the first coupling agent and the amount of the second coupling agent can vary within a certain range. The molar ratio of the first coupling agent to the first organolithium initiator is 0.2-0.3:1, preferably 0.21-0.26:1; the molar ratio of the second coupling agent to the second organolithium initiator is 0.1-0.17:1, preferably 0.1-0.15:1.

[0065] Preferably, the conditions for the first coupling reaction include: a temperature of 60-90°C and a time of 20-40 min. The conditions for the second coupling reaction include: a temperature of 60-90°C and a time of 20-40 min.

[0066] According to the present invention, the coupling reaction can be terminated by adding a terminator to obtain a polymerization solution of low-cis polybutadiene rubber. In order to extract the low-cis polybutadiene rubber, the solvent can be removed after termination (e.g., by steam condensation desolventizing treatment) and dried to extract the low-cis polybutadiene rubber.

[0067] Preferably, the terminator is one or more of C1-C4 alcohols, organic acids, and carbon dioxide, more preferably one or more of isopropanol, stearic acid, citric acid, and carbon dioxide, and even more preferably carbon dioxide. When carbon dioxide is used to terminate the reaction, it can form carbonates with metal ions (Li, Mg, Al, Fe, Zn) in the polymerization system and separate them from the polymer, thereby avoiding the color reaction of metal ions and giving the low-cis polybutadiene rubber a lower color intensity. The carbon dioxide can be introduced into the reaction system in the form of a gas (e.g., carbon dioxide gas with a gauge pressure of 0.2-1 MPa (e.g., 0.3-0.6 MPa)) or in the form of a dry ice aqueous solution (e.g., a concentration of 0.1-5 wt%).

[0068] In this invention, there is no particular limitation on the amount of the terminator. Preferably, the amount of the first terminator is 0.05-0.2 parts by weight relative to 100 parts by weight of butadiene 1, and the amount of the second terminator is 0.05-0.2 parts by weight relative to 100 parts by weight of butadiene 2.

[0069] To improve the antioxidant properties of the obtained low-cis polybutadiene rubber, an antioxidant may be introduced into the low-cis polybutadiene rubber. Preferably, an antioxidant is introduced into the terminated reaction system after termination, so that the polymerization solution of the resulting low-cis polybutadiene rubber contains an antioxidant. If it is necessary to remove the low-cis polybutadiene rubber, a solvent removal treatment can be performed after introducing the antioxidant. The present invention does not particularly limit the antioxidant used; it can be any conventional antioxidant in the art. For example, the antioxidant is one or more of 4,6-bis(octylthiomethyl)o-cresol (trade name: Antioxidant 1520), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester (trade name: Antioxidant 1076), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (trade name: Antioxidant 4020), N-isopropylphenyl-N'-phenyl-p-phenylenediamine (trade name: Antioxidant 4010NA), and N-phenyl-2-naphthylamine (trade name: Antioxidant D), preferably a combination of antioxidant 1520 and antioxidant 1076, more preferably a combination of antioxidant 1520 and antioxidant 1076 in a weight ratio of 1:1-3.

[0070] Preferably, the weight ratio of the antioxidant to butadiene is 0.1-0.6:100.

[0071] According to the present invention, the dry weight ratio of the low-cis polybutadiene rubber solution BR1 to the low-cis polybutadiene rubber solution BR2 is 1:2.5-4, preferably 1:2.8-3.5.

[0072] According to the present invention, a low-cis polybutadiene rubber solution BR1 and a low-cis polybutadiene rubber solution BR2 are mixed and the solvent is removed to obtain the low-cis polybutadiene rubber; wherein, the method for removing the solvent from the polymer solution mixture of the low-cis polybutadiene rubber preferably includes: first subjecting the mixture of BR1 and BR2 to steam condensation treatment, and then extruding, dehydrating and drying.

[0073] According to the present invention, the steam condensation treatment can substantially remove the organic solvent from the mixture of BR1 and BR2, yielding colloidal particles with an oil content of 1-2% by weight and a water content of 40-60% by weight. The present invention does not particularly limit the steam condensation treatment; conventional steam condensation treatment methods in the art can be used.

[0074] According to the present invention, the extrusion dehydration can make the oil content of the rubber particles obtained by the steam condensation treatment reach less than 1% by weight and the water content reach 9-13% by weight. Then, by drying (for example, first drying with an expansion dryer and then drying with a hot air box), the low cis polybutadiene rubber of the present invention with a volatile content of less than 1% by weight can be obtained.

[0075] Surprisingly, the feeding process for the coagulation and drying of low-cis polybutadiene rubber was continuous and stable, with no issues such as material blockage, leakage, screw slippage, expansion and fire, granule discoloration, or granule agglomeration and caking. This demonstrates that the low-cis polybutadiene rubber provided by this invention can be readily produced.

[0076] A third aspect of the present invention provides a method for preparing HIPS resin, the method comprising: polymerizing styrene and a toughening agent in a benzene-based solvent in the presence of a free radical initiator; wherein the toughening agent contains the aforementioned low-cis polybutadiene rubber; wherein the benzene-based solvent is selected from at least one of unsubstituted or C1-C4 alkyl-substituted benzenes.

[0077] In this invention, the number-average molecular weight of low cis polybutadiene rubber exhibits a three-peak distribution, and its particle size exhibits a multi-level distribution. Furthermore, by controlling the number-average molecular weight and peak area of ​​the three-peak distribution, the viscosity of the rubber solution is suitable and the gel content is low. Using this low cis polybutadiene rubber as a toughening agent to prepare HIPS resin enables the HIPS resin to have excellent surface gloss and impact strength.

[0078] In this invention, the C1-C4 alkyl group is selected from at least one of methyl, ethyl, n-propyl, isopropyl, and n-butyl; wherein, the C1-C4 alkyl-substituted benzene as the benzene solvent can be single-site substituted or multi-site substituted; preferably, the benzene solvent is selected from at least one of benzene, toluene, ethylbenzene, and xylene.

[0079] In this invention, the benzene solvent can be the conventional amount used in the preparation of HIPS resin in the art. For example, based on the total weight of styrene, benzene solvent and toughening agent, the amount of benzene solvent is 6wt%-18wt%.

[0080] In this invention, the toughening agent contains the low-cis polybutadiene rubber obtained by the above-described method of this invention to obtain HIPS resin with high gloss and high impact resistance. In order to obtain HIPS resin with even better performance, the weight ratio of styrene to toughening agent on a dry weight basis is 550-1900:100, preferably 600-1600:100, more preferably 800-1400:100, and even more preferably 900-1300:100.

[0081] In this invention, the free radical initiator can be any type of initiator conventionally used in the preparation of HIPS resins. For example, the free radical initiator can be one or more thermally decomposable initiators, preferably selected from peroxide initiators and / or azobisnitrile compound initiators, more preferably one or more of peroxy-2-ethylhexyl tert-butyl carbonate, diacyl peroxide, dicarbonate peroxide, carboxylic acid peroxide, alkyl peroxide, and azobisnitrile compounds, and even more preferably one or more of benzoyl peroxide, di-o-methylbenzoyl peroxide, tert-butyl peroxide, dicumyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile. In this invention, the weight ratio of styrene to the free radical initiator is 2500-12000:1, more preferably 3000-9500:1, more preferably 4000-9000:1, and even more preferably 5000-8500:1.

[0082] In this invention, the polymerization reaction can incorporate various additives to enhance the overall performance of HIPS, namely, high surface gloss and impact resistance. Preferably, the additive is mineral oil. In this invention, the amount of mineral oil used is 2-5 parts by weight relative to 100 parts by weight of styrene.

[0083] In this invention, the conditions for the polymerization reaction include: a temperature of 100-150°C and a time of 7-9 hours.

[0084] In a preferred embodiment of the present invention, the polymerization reaction conditions include: reacting at 100-110°C for 1-3 hours, then reacting at 115-125°C for 1-3 hours (e.g., 1-2 hours), then reacting at 130-140°C for 1-3 hours (e.g., 1-2 hours), and finally reacting at 145-155°C for 1-3 hours (e.g., 1-2.5 hours). More preferably, the polymerization reaction conditions include: reacting at 105-110°C for 1.5-2.5 hours, then reacting at 120-125°C for 1.5-2.5 hours, then reacting at 130-135°C for 1.5-2.5 hours, and finally reacting at 150-155°C for 1.5-2.5 hours. This polymerization reaction can be carried out under stirring, for example, at 100-400 rpm.

[0085] A fourth aspect of the present invention provides a HIPS resin prepared by the above method.

[0086] According to the present invention, the content of styrene structural units in the HIPS resin is 85wt%-95wt%, preferably 88wt%-94wt%.

[0087] In this invention, the HIPS resin, after removing the styrene structural units, mainly consists of butadiene structural units. This can be understood as the remaining content being the content of butadiene structural units, that is, the content of butadiene structural units is 5wt%-15wt%, preferably 6wt%-12wt%.

[0088] According to the present invention, the weight-average molecular weight of the HIPS resin is 150,000-400,000 g / mol, preferably 200,000-300,000 g / mol.

[0089] According to the present invention, the molecular weight distribution coefficient of the HIPS resin is 2-2.9.

[0090] The HIPS resin prepared by the method of the present invention has high impact resistance and high gloss. Preferably, the cantilever beam impact strength of the HIPS resin is 14 kJ / m. 2 The above is preferably 15 kJ / m 2 The above, more preferably 15-17 kJ / m 2 The surface gloss (60°) of the HIPS resin is 69 or higher, preferably 70 or higher, and more preferably 75 or higher.

[0091] The present invention will be described in detail below through embodiments.

[0092] In the following examples and comparative examples, the monomer conversion rate was determined by gravimetric method, which is the weight percentage of the polymer after solvent removal to the theoretical polymer yield.

[0093] The content of 1,2-polymer structural units in low-cis polybutadiene rubber is measured by measuring the vinyl content, using a BRUKER AVANCED RDX 400MHz nuclear magnetic resonance spectrometer with a frequency of 400MHz, deuterated chloroform as the solvent, and tetramethylsilane as the built-in standard.

[0094] Molecular weight and molecular weight distribution were determined using an HLC-8320 gel permeation chromatograph from Tosoh Corporation, Japan. The test conditions included: TSKgel SuperMultipore HZ-N column, TSKgel SuperMultipore HZ standard column, chromatographic grade THF solvent, polystyrene as calibration standard, sample concentration of 1 mg / mL, injection volume of 10.00 μL, flow rate of 0.35 mL / min, and test temperature of 40 °C.

[0095] The viscosity of a 5 wt% styrene solution of low cis polybutadiene rubber was determined using a capillary viscometer at a constant temperature of 25°C.

[0096] The gel content of low-cis polybutadiene rubber was determined by gravimetric method. After filtration through a 400-mesh (38 μm) sieve, the ratio of the weight of the residue to the amount of rubber used was calculated.

[0097] Mooney viscosity was measured using a GT-7080-S2 Mooney viscometer manufactured by Taiwan High Speed ​​Rail Corporation, according to the method specified in Chinese National Standard GB / T1232.1-2016. The test conditions were: preheating time 1 min, rotation time 4 min, and test temperature 100℃.

[0098] The APHA colorimetric test method is as follows: a low-cis polybutadiene rubber sample is prepared into a 5wt% styrene solution and measured using a Lico620 colorimeter with a colorimetric tube diameter of 11mm.

[0099] The mechanical properties of HIPS were tested using an INSTRON 5567 universal testing machine (UK). The notched impact strength of the cantilever beam was measured according to GB / T1843-2018 standard (kJ / m²). 2 ).

[0100] The 60° gloss level was determined according to ASTM D526 (60°).

[0101] In the following examples and comparative examples:

[0102] Antioxidant 1520 was purchased from Sinopharm Reagent Company and was of analytical grade.

[0103] Antioxidant 1076 was purchased from Inokai Reagents, analytical grade;

[0104] Tetrahydrofurfuryl ethyl ether was purchased from Bailingwei Reagent Company, 99 wt%;

[0105] The n-butyllithium was purchased from Bailingwei Reagent Company and diluted with hexane to a concentration of 0.4 mol / L.

[0106] The mineral oil was supplied by the No. 1 Chemical Plant of Beijing Yanshan Petrochemical Company, and its density is 0.85-0.88 g / ml.

[0107] Organic solvent A: A mixed solvent of cyclohexane and hexane in a mass ratio of 1:0.2.

[0108] Antioxidant A: A combination of antioxidant 1520 and antioxidant 1076 in a weight ratio of 1:2.

[0109] Antioxidant B: A combination of antioxidant 1520 and antioxidant 1076 in a weight ratio of 1:1.

[0110] Preparation Example 1A

[0111] Under nitrogen protection, organic solvent, 1,3-butadiene monomer, and structure modifier were added to the reactor and heated to the polymerization temperature. An organolithium initiator was then added, followed by anionic solution polymerization at this temperature to obtain polymerization solution 1. The monomer conversion rate is shown in Table 1. A first coupling agent was then added to polymerization solution 1 to initiate a coupling reaction under coupling conditions. A terminator was added to terminate the coupling reaction, and then an antioxidant was added and mixed to finally obtain the polymerization solution LCBR 1A of low-cis polybutadiene rubber. The types and amounts of coupling agents, terminators, and antioxidants, as well as the polymerization and coupling reaction conditions, are shown in Table 1.

[0112] Preparation Examples 2A-10A

[0113] Polymerization solutions LCBR 2A-LCBR10A of low-cis polybutadiene rubber were prepared according to the method described in Preparation Example 1A, except that the reactions were carried out using the parameters shown in Table 1.

[0114] Preparation Examples 1B-10B

[0115] The polymerization solutions LCBR 1B-LCBR10B of low-cis polybutadiene rubber were prepared according to the method described in Preparation Example 1A, except that the reactions were carried out using the parameters shown in Table 2.

[0116] Preparation Example 1C-3C

[0117] Linear polymerization solutions of low-cis polybutadiene rubber, LCBR 1C-LCBR 3C, were prepared according to the method described in Preparation Example 1A, except that the reactions were carried out using the parameters shown in Table 2. The number average molecular weights of the low-cis polybutadiene linear polymers in LCBR1C-LCBR 3C were 37,800 g / mol, 126,000 g / mol, and 336,000 g / mol, respectively.

[0118] Table 1

[0119]

[0120] Continued from Table 1

[0121]

[0122]

[0123] Note: All dosages listed in Table 1 are based on pure compounds.

[0124] Table 2

[0125]

[0126] Table 2

[0127]

[0128]

[0129] Table 2

[0130]

[0131] Note: All dosages listed in Table 2 are based on pure compounds.

[0132] Example 1

[0133] The low-cis polybutadiene rubber LCBR1A solution and the low-cis polybutadiene rubber LCBR1B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C1 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0134] Example 2

[0135] The low-cis polybutadiene rubber LCBR2A solution and the low-cis polybutadiene rubber LCBR2B solution were mixed at a dry rubber weight ratio of LCBR 2A to LCBR 2B of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C2 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0136] Example 3

[0137] The low-cis polybutadiene rubber LCBR3A solution and the low-cis polybutadiene rubber LCBR3B solution were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C3 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0138] Example 4

[0139] The low-cis polybutadiene rubber LCBR4A solution and the low-cis polybutadiene rubber LCBR4B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C4 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0140] Example 5

[0141] The low-cis polybutadiene rubber LCBR5A solution and the low-cis polybutadiene rubber LCBR5B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C5 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0142] Example 6

[0143] The low-cis polybutadiene rubber LCBR6A solution and the low-cis polybutadiene rubber LCBR6B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C6 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0144] Example 7

[0145] The low-cis polybutadiene rubber LCBR7A solution and the low-cis polybutadiene rubber LCBR7B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber C7 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0146] Example 8

[0147] According to the method described in Example 1, except that the low-cis polybutadiene rubber LCBR7B was used instead of LCBR1B in Example 1, the organic solvent was removed by steam condensation treatment and dried to obtain the low-cis polybutadiene rubber C8 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0148] Example 9

[0149] According to the method described in Example 1, except that the low-cis polybutadiene rubber LCBR7A was used instead of LCBR1A in Example 1, the organic solvent was removed by steam condensation treatment and dried to obtain the low-cis polybutadiene rubber C9 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0150] Example 10

[0151] According to the method described in Example 1, except that LCBR 1A and LCBR 1B were mixed at a dry rubber weight ratio of 1:2.5, the organic solvent was removed by steam condensation treatment and dried to obtain the low cis polybutadiene rubber C10 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0152] Example 11

[0153] According to the method described in Example 1, except that LCBR 1A and LCBR 1B were mixed at a dry rubber weight ratio of 1:3.5, the organic solvent was removed by steam condensation treatment and dried to obtain the low cis polybutadiene rubber C11 of the present invention. Its structure and properties were measured and the results are shown in Table 3.

[0154] Example 12

[0155] According to the method described in Example 1, except that LCBR 1A and LCBR 1B were mixed at a dry rubber weight ratio of 1:4.5, the organic solvent was removed by steam condensation treatment and dried to obtain the low cis polybutadiene rubber C12 of the present invention. Its structure and properties were measured and the results are shown in Table 3.

[0156] Comparative Example 1

[0157] The low-cis polybutadiene rubber LCBR8A solution and the low-cis polybutadiene rubber LCBR8B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber DB1 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0158] Comparative Example 2

[0159] The low-cis polybutadiene rubber LCBR9A solution and the low-cis polybutadiene rubber LCBR9B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber DB2 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0160] Comparative Example 3

[0161] The low-cis polybutadiene rubber LCBR10A solution and the low-cis polybutadiene rubber LCBR10B were mixed at a dry rubber weight ratio of 1:3. The organic solvent was removed by steam condensation treatment and then dried to obtain the low-cis polybutadiene rubber DB3 of the present invention. Its structure and properties were measured, and the results are shown in Table 3.

[0162] Comparative Example 4

[0163] The low-cis polybutadiene linear polymers in LCBR 1C, LCBR 1C and LCBR 3C were mixed at a dry weight ratio of 1:52.9:23.1 to obtain a low-cis polybutadiene rubber linear copolymer. The structure and properties of the copolymer were determined, and the results are shown in Table 3.

[0164] Table 3

[0165]

[0166]

[0167] Continued from Table 3

[0168]

[0169] As can be seen from Table 3, the viscosity of a 5wt% styrene solution of the low cis polybutadiene rubber with a trimodal molecular weight distribution obtained in this invention is between 80-128 cp, the gel content is not higher than 150 ppm, and the color is low, making the low cis polybutadiene rubber of this invention particularly suitable for HIPS modification.

[0170] Test Example 1

[0171] 100g of low-cis polybutadiene rubber C1, 150g of ethylbenzene, and 1100g of styrene monomer were mixed, and then 45g of mineral oil and 0.2g of peroxy-2-ethylhexyl tert-butyl carbonate were added and mixed. The mixture was polymerized at a stirring speed of 300 rpm and a polymerization temperature of 105℃ for 2 hours, and then the temperature was increased to 120℃ for 2 hours. The mixture was then polymerized at a stirring speed of 100 rpm and a temperature of 135℃ for 2 hours, and finally the temperature was increased to 150℃ for 2 hours. The reaction product was then subjected to vacuum flash evaporation to remove unreacted monomers and solvents to obtain HIPS resin P1.

[0172] The structure and properties of the HIPS resin P1 were measured after drying, and the results are shown in Table 4.

[0173] Test Example 2

[0174] 120g of low-cis polybutadiene rubber C2, 120g of xylene, and 1100g of styrene monomer were mixed, and then 50g of mineral oil and 0.2g of azobisisobutyronitrile were added and mixed. The mixture was polymerized at a stirring speed of 350rpm and a polymerization temperature of 110℃ for 1.5h, and then the temperature was increased to 120℃ for 2.5h. The mixture was then polymerized at a stirring speed of 200rpm and a temperature of 130℃ for 1.5h, and finally the temperature was increased to 155℃ for 2h. The reaction product was then subjected to vacuum flash evaporation to remove unreacted monomers and solvents to obtain HIPS resin P2.

[0175] The structure and properties of the HIPS resin P2 were measured after drying, and the results are shown in Table 4.

[0176] Test Example 3-11

[0177] According to the method described in Test Example 1, the difference is that low-cis polybutadiene rubber C3-C12 is used instead of low-cis polybutadiene rubber C1, so that the reaction products are obtained by vacuum flash evaporation, removal of unreacted monomers and solvents, respectively, to obtain HIPS resins P3-P12.

[0178] The structure and properties of HIPS resins P3-P12 were measured after drying, and the results are shown in Table 4.

[0179] Comparative test cases 1-4

[0180] According to the method described in Test Example 1, the difference is that low-cis polybutadiene rubbers DC1-DC4 are used instead of low-cis polybutadiene rubber C1, so that the reaction products are obtained by vacuum flash evaporation, removal of unreacted monomers and solvents, respectively, to obtain HIPS resins DP1-DP4.

[0181] The structure and properties of HIPS resins DP1-DP4 were measured after drying, and the results are shown in Table 4.

[0182] Comparative test cases 5-7

[0183] According to the method described in Test Example 1, the difference is that Asahi Kasei low-cis polybutadiene rubbers 720A, 35AE and 55AE were used instead of low-cis polybutadiene rubber C1, respectively, so that the reaction products were obtained by vacuum flash evaporation, removal of unreacted monomers and solvents, respectively, to obtain HIPS resins DP5-DP7.

[0184] The structure and properties of HIPS resins DP5-DP7 were measured after drying, and the results are shown in Table 4.

[0185] Table 4

[0186]

[0187] As can be seen from Table 4, using low-cis polybutadiene containing the present invention as a toughening agent can produce HIPS resin with strong impact resistance and high gloss. Compared with HIPS resin obtained by using commercially available toughening agents, the HIPS resin obtained by the present invention has significantly improved impact resistance and gloss.

[0188] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A low-cis polybutadiene rubber, characterized in that, The low-cis polybutadiene rubber exhibits a three-peaked number-average molecular weight distribution: the first peak has a number-average molecular weight of 310,000-360,000 g / mol, the second peak has a number-average molecular weight of 120,000-150,000 g / mol, and the third peak has a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%. The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

2. The low-cis polybutadiene rubber according to claim 1, wherein, The number-average molecular weight of the first peak is 320,000-355,000 g / mol; the peak area of ​​the first peak is 25%-40%. And / or, the number-average molecular weight of the second peak is 125,000-145,000 g / mol; the peak area of ​​the second peak is 57%-75%; And / or, the number-average molecular weight of the third peak is 37,000-46,000 g / mol; the peak area of ​​the third peak is 0.6%-5%.

3. The low-cis polybutadiene rubber according to claim 1 or 2, wherein, The number-average molecular weight of the first peak is 330,000-350,000 g / mol; the peak area of ​​the first peak is 27%-36%. And / or, the number-average molecular weight of the second peak is 130,000-140,000 g / mol; the peak area of ​​the second peak is 62%-72%; And / or, the number-average molecular weight of the third peak is 38,000-45,000 g / mol; the peak area of ​​the third peak is 0.8%-3%.

4. The low-cis polybutadiene rubber according to claim 1 or 2, wherein, The viscosity of the low-cis polybutadiene rubber in a 5wt% styrene solution at 25°C is 80-130 cp. And / or, the Mooney viscosity ML of the low cis polybutadiene rubber is 40-55, and the test conditions for the Mooney viscosity are: preheating time 1 min, rotation time 4 min, and test temperature 100℃. And / or, the gel content of the low-cis polybutadiene rubber is not higher than 150 ppm; And / or, the vinyl content of the low-cis polybutadiene rubber is 8%-20 wt%; And / or, the color of the 5wt% styrene solution of the low cis polybutadiene rubber is less than or equal to 15 APHA.

5. The low-cis polybutadiene rubber according to claim 4, wherein, The viscosity of the low-cis polybutadiene rubber in a 5wt% styrene solution at 25°C is 90-110 cp. And / or, the gel content of the low-cis polybutadiene rubber is not higher than 100 ppm; And / or, the vinyl content of the low-cis polybutadiene rubber is 10%-16 wt%; And / or, the color of the 5wt% styrene solution of the low cis polybutadiene rubber is less than or equal to 8 APHA.

6. The low-cis polybutadiene rubber according to claim 5, wherein, The gel content of the low-cis polybutadiene rubber is not higher than 80 ppm; And / or, the color of the 5wt% styrene solution of the low cis polybutadiene rubber is less than or equal to 5 APHA.

7. A method for preparing low-cis polybutadiene rubber, characterized in that, The method includes the following steps: Low-cis polybutadiene rubber solution BR1 and low-cis polybutadiene rubber solution BR2 are mixed, and the solvent is removed to obtain the low-cis polybutadiene rubber. The amounts of the low-cis polybutadiene rubber solution BR1 and the low-cis polybutadiene rubber solution BR2 are such that the number-average molecular weight of the obtained low-cis polybutadiene rubber exhibits a three-peak distribution: the first peak has a number-average molecular weight of 310,000-360,000 g / mol, the second peak has a number-average molecular weight of 120,000-150,000 g / mol, and the third peak has a number-average molecular weight of 36,000-48,000 g / mol; wherein the peak area of ​​the first peak is 21%-44%, the peak area of ​​the second peak is 51%-79%, and the peak area of ​​the third peak is 0.4%-8%. The low-cis polybutadiene rubber is a coupled low-cis polybutadiene rubber.

8. The preparation method according to claim 7, wherein, The preparation method of the low-cis polybutadiene rubber solution BR1 includes the following steps: Under anionic polymerization conditions, butadiene 1 is subjected to a first polymerization in an organic solvent in the presence of a first organolithium initiator and a first structure modifier to obtain a polymerization solution 1; the polymerization solution 1 is contacted with a first coupling agent to carry out a first coupling reaction, and then a first terminator is added to obtain a low-cis polybutadiene rubber solution BR1.

9. The preparation method according to claim 7, wherein, The preparation method of the low-cis polybutadiene rubber solution BR2 includes the following steps: Under anionic polymerization conditions, butadiene 2 is subjected to a second polymerization in an organic solvent in the presence of a second organolithium initiator and a second structure modifier to obtain a polymerization solution 2; the polymerization solution 2 is then contacted with a second coupling agent to carry out a second coupling reaction, and a second terminator is added to obtain a low-cis polybutadiene rubber solution BR2.

10. The preparation method according to claim 8, wherein, The molar ratio of butadiene 1 to the first organolithium initiator is 650-900:1; And / or, the molar ratio of the first coupling agent to the first organolithium initiator is 0.2-0.3:

1.

11. The preparation method according to claim 10, wherein, The molar ratio of butadiene 1 to the first organolithium initiator is 680-850:1; And / or, the molar ratio of the first coupling agent to the first organolithium initiator is 0.21-0.26:

1.

12. The preparation method according to claim 11, wherein, The molar ratio of butadiene 1 to the first organolithium initiator is 700-830:

1.

13. The preparation method according to claim 9, wherein, The molar ratio of butadiene 2 to the second organolithium initiator is 2200-2800:1; And / or, the molar ratio of the second coupling agent to the second organolithium initiator is 0.1-0.17:

1.

14. The preparation method according to claim 13, wherein, The molar ratio of butadiene 2 to the second organolithium initiator is 2300-2700:1; And / or, the molar ratio of the second coupling agent to the second organolithium initiator is 0.1-0.15:

1.

15. The preparation method according to claim 14, wherein, The molar ratio of butadiene 2 to the second organolithium initiator is 2400-2600:

1.

16. The preparation method according to claim 7, wherein, The dry weight ratio of the low-cis polybutadiene rubber solution BR1 to the low-cis polybutadiene rubber solution BR2 is 1:2.5-4.

17. The preparation method according to claim 16, wherein, The dry weight ratio of the low-cis polybutadiene rubber solution BR1 to the low-cis polybutadiene rubber solution BR2 is 1:2.8-3.

5.

18. The preparation method according to claim 8 or 9, wherein, The first organolithium initiator and / or the second organolithium initiator are each independently a compound represented by Formula I. R 1 Formula I of Li Among them, R 1 Selected from C1-C 10 Alkyl groups.

19. The preparation method according to claim 18, wherein, The first organolithium initiator and / or the second organolithium initiator are each independently selected from at least one of n-butyllithium, sec-butyllithium, isobutyllithium and tert-butyllithium; And / or, the first coupling agent and / or the second coupling agent are each independently a silane coupling agent.

20. The preparation method according to claim 19, wherein, The first organolithium initiator and / or the second organolithium initiator are each independently n-butyllithium and / or sec-butyllithium; And / or, the first coupling agent and / or the second coupling agent are each independently at least one of silicon tetrachloride, silicon tetrabromide and tin tetrachloride.

21. The preparation method according to claim 20, wherein, The first organolithium initiator and / or the second organolithium initiator are each independently n-butyllithium; And / or, the first coupling agent and / or the second coupling agent are each independently silicon tetrachloride.

22. The preparation method according to claim 8 or 9, wherein, The first terminator and / or the second terminator are each independently selected from at least one of C1-C4 alcohols, organic acids and carbon dioxide.

23. The preparation method according to claim 22, wherein, The first terminator and / or the second terminator are each independently selected from at least one of isopropanol, stearic acid, citric acid and carbon dioxide.

24. The preparation method according to claim 23, wherein, The first terminator and / or the second terminator are each independently carbon dioxide.

25. The preparation method according to claim 8, wherein, The conditions for the first polymerization include: a temperature of 0-100℃ and a time of 20-100 min; And / or, the conditions for the first coupling reaction include: a temperature of 60-90°C and a time of 20-40 min.

26. The preparation method according to claim 25, wherein, The conditions for the first polymerization include: a temperature of 40-100℃ and a time of 30-60 min.

27. The preparation method according to claim 26, wherein, The conditions for the first polymerization include a temperature of 50-100°C.

28. The preparation method according to claim 9, wherein, The conditions for the second polymerization include: a temperature of 0-100℃ and a time of 20-100 min; And / or, the conditions for the second coupling reaction include: a temperature of 60-90°C and a time of 20-40 min.

29. The preparation method according to claim 28, wherein, The conditions for the second polymerization include: a temperature of 40-100℃ and a time of 30-60 min.

30. The preparation method according to claim 29, wherein, The conditions for the second polymerization include a temperature of 50-100°C.

31. A method for preparing HIPS resin, the method comprising: In a benzene-based solvent, styrene and a toughening agent are polymerized in the presence of a free radical initiator; wherein the toughening agent contains the low-cis polybutadiene rubber according to any one of claims 1-6; wherein the benzene-based solvent is selected from at least one of unsubstituted or C1-C4 alkyl-substituted benzenes.

32. The method according to claim 31, wherein, Based on the total weight of styrene, benzene solvents and toughening agents, the amount of benzene solvents used is 6wt%-18wt%.

33. The method according to claim 31, wherein, The weight ratio of styrene to toughening agent (dry weight) is 550-1900:

100.

34. The method according to claim 33, wherein, The weight ratio of styrene to toughening agent (dry weight) is 600-1600:

100.

35. The method according to claim 34, wherein, The weight ratio of styrene to toughening agent (dry weight) is 800-1400:

100.

36. The method according to claim 35, wherein, The weight ratio of styrene to toughening agent (dry weight) is 900-1300:

100.

37. The method according to claim 31 or 32, wherein, The free radical initiator is at least one of peroxydiacyl, peroxydicarbonate, peroxycarboxylic acid ester, alkyl peroxide, and azobisnitrile compounds.

38. The method according to claim 31 or 32, wherein, The free radical initiator is at least one selected from the following: 2-ethylhexyl tert-butyl peroxide, benzoyl peroxide, di-o-methylbenzoyl peroxide, tert-butyl peroxide, dicumyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile. And / or, the weight ratio of the amount of styrene to the amount of the free radical initiator is 2500-12000:

1.

39. The method according to claim 38, wherein, The weight ratio of the amount of styrene to the amount of the free radical initiator is 3000-9500:

1.

40. The method according to claim 39, wherein, The weight ratio of the amount of styrene to the amount of the free radical initiator is 4000-9000:

1.

41. The method according to claim 40, wherein, The weight ratio of the amount of styrene to the amount of the free radical initiator is 5000-8500:

1.

42. The method according to claim 31, wherein, The conditions for the polymerization reaction include: a temperature of 100-150℃ and a time of 7-9 hours; Alternatively, the polymerization reaction conditions may include: reacting at 100-110°C for 1-3 hours, then at 115-125°C for 1-3 hours, then at 130-140°C for 1-3 hours, and finally at 145-155°C for 1-3 hours.

43. The method according to claim 42, wherein, The polymerization reaction conditions include: first reacting at 105-110℃ for 1.5-2.5h, then reacting at 120-125℃ for 1.5-2.5h, then reacting at 130-135℃ for 1.5-2.5h, and finally reacting at 150-155℃ for 1.5-2.5h.

44. A HIPS resin prepared by the method according to any one of claims 31-43.

45. The HIPS resin according to claim 44, wherein, The styrene structural units in the HIPS resin are 85wt%-95wt%; And / or, the weight-average molecular weight of the HIPS resin is 150,000-400,000 g / mol; And / or, the molecular weight distribution coefficient of the HIPS resin is 2-2.9; And / or, the cantilever beam impact strength of the HIPS resin is 14 kJ / m. 2 above; And / or, the HIPS resin has a surface gloss of 69 or higher at 60°.

46. ​​The HIPS resin according to claim 45, wherein, The styrene structural units in the HIPS resin are 88wt%-94wt%; And / or, the weight-average molecular weight of the HIPS resin is 200,000-300,000 g / mol; And / or, the cantilever beam impact strength of the HIPS resin is 15 kJ / m. 2 above; And / or, the HIPS resin has a surface gloss of 70 or higher at 60°.

47. The HIPS resin according to claim 45, wherein, The cantilever beam impact strength of the HIPS resin is 15-17 kJ / m. 2 ; And / or, the HIPS resin has a surface gloss of 75 or higher at 60°.

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