CN109503763B

CN109503763B - Butadiene-isoprene copolymer and method for producing same, and aromatic vinyl resin and method for producing same

Info

Publication number: CN109503763B
Application number: CN201710827281.1A
Authority: CN
Inventors: 李建成; 徐林; 王雪; 毕海鹏; 刘天鹤; 赵姜维
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2017-09-14
Filing date: 2017-09-14
Publication date: 2021-11-19
Anticipated expiration: 2037-09-14
Also published as: CN109503763A

Abstract

The invention discloses a butadiene-isoprene copolymer and a preparation method thereof, wherein the butadiene-isoprene copolymer has wider molecular weight distribution, is used as a toughening agent of aromatic vinyl resin, and can effectively improve the impact resistance of the aromatic vinyl resin. The invention also discloses aromatic vinyl resin and a preparation method thereof, the preparation method directly mixes the polymerization solution containing the butadiene-isoprene copolymer and the polymerization solution containing the butadiene-isoprene copolymer with the aromatic vinyl monomer and then carries out bulk polymerization to prepare the aromatic vinyl resin, thereby simplifying the process operation, shortening the process flow, being beneficial to reducing the overall operation energy consumption and improving the production efficiency, and the prepared aromatic vinyl resin shows obviously improved impact resistance.

Description

Butadiene-isoprene copolymer and method for producing same, and aromatic vinyl resin and method for producing same

Technical Field

The invention relates to a butadiene-isoprene copolymer and a preparation method thereof, and also relates to an aromatic vinyl resin using the butadiene-isoprene copolymer as a toughening agent and a preparation method thereof.

Background

Conventional HIPS resins (i.e., high impact polystyrene) are obtained by thermal polymerization (or radical polymerization) of rubber as a toughening agent and styrene monomer by a bulk polymerization method. The rubbers conventionally selected as toughening agents may be butadiene-isoprene copolymer (LCBR), high cis-polybutadiene rubber (HCBR), solution-polymerized styrene-butadiene rubber (SSBR), styrene-butadiene-styrene copolymer (SBS), with LCBR and its derivatives (linear styrene-butadiene copolymer and butadiene-isoprene copolymer) being most preferred.

However, butadiene-isoprene copolymers prepared by anionic polymerization have inherent characteristics of living polymerization products, i.e., generally narrow molecular weight distribution and single rubber particle size distribution (generally less than 1.5, and generally in the range of 1 to 1.2), which easily results in deterioration of processability of the rubber and at the same time is disadvantageous in improving impact resistance of the resin.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a butadiene-isoprene copolymer which has wider molecular weight distribution and aromatic vinyl resin prepared by using the butadiene-isoprene copolymer as a toughening agent has obviously improved impact resistance.

According to a first aspect of the present invention, there is provided a butadiene-isoprene copolymer having a bimodal distribution of molecular weights, a number average molecular weight of a low molecular weight component in the bimodal is in the range of 50000-120000, a molecular weight distribution index is 1.6-2.1, a number average molecular weight of a high molecular weight component in the bimodal is in the range of 160000-380000, and a molecular weight distribution index is 1.6-2.1, wherein the content of the high molecular weight component is 50-95 wt%, the content of butadiene structural units is 20-80 wt%, and the content of isoprene structural units is 20-80 wt%, based on the total amount of the copolymer.

According to a second aspect of the present invention, there is provided a method for preparing a butadiene-isoprene copolymer, the method comprising the steps of:

(a) under the condition of anion initiation reaction, isoprene and a first part of butadiene are contacted with an organic lithium initiator in alkylbenzene to carry out initiation reaction;

(b) adding a retarder to the mixture resulting from the initiation reaction of step (a), and subjecting the mixture with retarder added to a first polymerization reaction under anionic polymerization conditions;

(c) carrying out second polymerization reaction on the mixture obtained by the first polymerization reaction and a second part of butadiene;

(d) under the condition of coupling reaction, the mixture obtained by the second polymerization reaction is contacted with a coupling agent to carry out coupling reaction;

(e) and contacting the mixture obtained by the coupling reaction with a terminating agent to carry out termination reaction to obtain a polymerization solution containing the butadiene-isoprene copolymer.

According to a third aspect of the present invention, there is provided a polymerization solution containing a butadiene-isoprene copolymer prepared by the method according to the first aspect of the present invention.

According to a fourth aspect of the present invention, there is provided an aromatic vinyl resin comprising structural units derived from an aromatic vinyl monomer and structural units derived from a toughening agent, wherein the toughening agent is the butadiene-isoprene copolymer according to the first aspect of the present invention.

According to a fifth aspect of the present invention, there is provided a method for producing an aromatic vinyl resin, the method comprising: under the condition of free radical polymerization, mixing a polymerization monomer containing an aromatic vinyl monomer with a solution containing a toughening agent, and polymerizing the obtained mixture, wherein the solution containing the toughening agent is the polymerization solution containing the butadiene-isoprene copolymer according to the third aspect of the invention.

The butadiene-isoprene copolymer of the present invention has a wide molecular weight distribution, and can be used as a toughening agent for aromatic vinyl resins to effectively improve the impact resistance of the aromatic vinyl resins. Different from the existing bulk method for preparing aromatic vinyl resin, according to the preparation method of aromatic vinyl resin provided by the invention, butadiene-isoprene copolymer is not dried, granulated and dissolved, but the polymerization solution of butadiene-isoprene copolymer and aromatic vinyl monomer are directly mixed for bulk polymerization, so that the aromatic vinyl resin is prepared, the process operation is simplified, the process flow is shortened, the overall operation energy consumption is reduced, and more importantly, the prepared aromatic vinyl resin has obviously improved impact resistance.

Detailed Description

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

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

According to a first aspect of the present invention, there is provided a butadiene-isoprene copolymer having a bimodal distribution of molecular weights, the number average molecular weight (i.e., M) of the low molecular weight component of the bimodal distribution_n) Molecular weight distribution index (i.e. M00-100000) in the range of 50000-120000, preferably in the range of 60000-100000_w/M_nWherein M is_wWeight average molecular weight) of 1.7 to 2.0, the number average molecular weight of the high molecular weight component in the doublet is in the range of 160000-380000, preferably in the range of 190000-320000, and the molecular weight distribution index is 1.7 to 2.0.

The butadiene-isoprene copolymer according to the present invention has a content of the high molecular weight component of 50 to 95% by weight, preferably 55 to 92% by weight, more preferably 60 to 90% by weight, based on the total amount of the copolymer.

According to the butadiene-isoprene copolymer of the present invention, the low molecular weight component in the bimodal is a linear polymer (i.e., an uncoupled polymer) and the high molecular weight component in the bimodal is a coupled polymer (i.e., a star-branched polymer). The coupled polymer includes a coupling center and a linear chain bonded to the coupling center, the linear chain being derived from the linear polymer. The butadiene-isoprene copolymer according to the present invention can be obtained by coupling a linear polymer with a coupling agent to form a mixture containing an uncoupled polymer (i.e., a low-molecular-weight component) and a coupled polymer (i.e., a high-molecular-weight component).

According to the butadiene-isoprene copolymer of the present invention, the molecular weight distribution index of the butadiene-isoprene copolymer is 1.9 to 2.5.

In the present invention, the molecular weight and molecular weight distribution index of the butadiene-isoprene copolymer are measured by gel permeation chromatography. The molecular weight distribution index of the butadiene-isoprene copolymer is the total molecular weight distribution index of the rubber, i.e., the molecular weight distribution index measured on the basis of the double peak; the molecular weight distribution index of the high molecular weight component in the double peak is a molecular weight distribution index calculated based on the elution peak corresponding to the high molecular weight component, and the molecular weight distribution index of the low molecular weight component in the double peak is a molecular weight distribution index calculated based on the elution peak corresponding to the low molecular weight component; the content of the high molecular weight component refers to the percentage value of the peak area of the bimodal peak corresponding to the eluting peak of the high molecular weight component to the total peak area of the bimodal peak.

The butadiene-isoprene copolymer according to the present invention may have a content of unsaturated side groups of 8 to 20 wt%, preferably 10 to 14 wt%, based on the total amount of the copolymer.

The unsaturated side groups in the butadiene-isoprene copolymer of the present invention are derived from a structural unit formed by 1, 2-polymerization of butadiene, a structural unit formed by 1, 2-polymerization of isoprene, and a structural unit formed by 3, 4-polymerization of isoprene. The content of the unsaturated side group can be determined by a nuclear magnetic resonance hydrogen spectrometry.

The butadiene-isoprene copolymer according to the present invention has a Mooney viscosity of 50 to 90, preferably 60 to 90, more preferably 70 to 85.

In the present invention, Mooney viscosity is measured by a Mooney viscometer model SMV-201SK-160 manufactured by Shimadzu corporation of Japan according to a method specified in the Chinese national standard GB/T1232-92, in a test mode: ML (1+4), test temperature 100 ℃.

The butadiene-isoprene copolymer according to the present invention has a gel content of less than 20ppm, preferably not more than 15ppm, more preferably not more than 10ppm, in terms of mass content.

In the present invention, the gel content is determined gravimetrically. The specific process is as follows: adding a polymer sample into styrene, shaking the mixture in a shaker at the temperature of 25 ℃ for 16 hours to completely dissolve soluble substances, preparing a styrene solution containing 5 weight percent of polymer, and recording the mass of the polymer sample as C (in grams); weighing a 360-mesh clean nickel screen, and recording the mass of the clean nickel screen as B (in grams); then filtering the solution by using a nickel screen; washing the nickel screen with styrene after filtering, drying the nickel screen for 30 minutes at 150 ℃ under normal pressure, weighing, and recording the mass of the nickel screen as A (in grams); the gel content was calculated according to the following formula:

gel content [ (% a-B)/C ] × 100%.

The butadiene-isoprene copolymer according to the present invention has a butadiene structural unit content of 15 to 85% by weight, preferably 20 to 80% by weight, more preferably 50 to 65% by weight, and an isoprene structural unit content of 15 to 85% by weight, preferably 20 to 80% by weight, more preferably 25 to 75% by weight, and further preferably 35 to 50% by weight, based on the total amount of the copolymer.

In the present invention, the term "butadiene structural unit" refers to a structural unit formed by polymerization of butadiene, and the term "isoprene structural unit" refers to a structural unit formed by polymerization of isoprene.

The butadiene-isoprene copolymer according to the present invention has a butadiene structural unit as an end group.

In the step (a), alkylbenzene is used as a polymerization solvent. The alkylbenzene may be one or a combination of two or more of monoalkylbenzene, dialkylbenzene and trialkylbenzene. Specifically, the alkylbenzene can be selected from compounds shown in formula II,

in the formula II, R₁And R₂Are the same or different and are each independently selected from a hydrogen atom or C₁-C₅An alkyl group such as a hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, or neopentyl group, and R₁And R₂Not simultaneously hydrogen atoms.

Preferably, the alkylbenzene is one or more of toluene, ethylbenzene and xylene. More preferably, the alkylbenzene is ethylbenzene.

In the step (a), the alkylbenzene is used as the polymerization solvent in an amount such that the concentration of the polymerization monomer is 5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, further preferably 20% by weight or more, further preferably 25% by weight or more, and particularly preferably 30% by weight or more. The alkylbenzene may be used in an amount such that the concentration of the polymerized monomer is 70 wt% or less, preferably 65 wt% or less, and more preferably 60 wt% or less. The alkylbenzene is used in such an amount that the concentration of the polymerized monomer is preferably 30 to 60% by weight, more preferably 35 to 55% by weight, and still more preferably 40 to 55% by weight, and the polymerization solution containing the butadiene-isoprene copolymer polymerized at the above monomer concentration can be used directly without removing the solvent for bulk polymerization by mixing with the monomer for polymerization of an aromatic vinyl resin to prepare an aromatic vinyl resin such as HIPS resin.

In step (a), the initiation reaction is used to contact the polymerized monomer with the organolithium initiator and carry out oligomerization to obtain an oligomer with a reactive end group, such as an oligomer with a molecular weight of 100-200 and a reactive end group. Generally, the initiation reaction may be carried out at a temperature of 10 to 50 ℃, preferably 25 to 40 ℃, more preferably 30 to 40 ℃. The time for the initiation reaction may be 1 to 8 minutes, preferably 1 to 5 minutes, more preferably 2 to 4.5 minutes, and further preferably 3 to 4 minutes.

In the step (a), the organolithium initiator may be any organolithium initiator commonly used in the field of anionic polymerization and capable of initiating polymerization of butadiene and isoprene. The organolithium initiator is preferably an organomonolithium compound, more preferably a compound represented by formula III,

R₃li (formula III)

In the formula III, R₃Is C₁-C₁₀Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, hexyl (including various isomers of hexyl), heptyl (including various isomers of heptyl), octyl (including various isomers of octyl), nonyl (including various isomers of nonyl), or decyl (including various isomers of decyl).

Specific examples of the organolithium initiator may include, but are not limited to: one or more of ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium and isobutyllithium.

Preferably, the organolithium initiator is one or more of n-butyllithium, sec-butyllithium, isobutyllithium, and tert-butyllithium. More preferably, the organolithium initiator is n-butyllithium.

The amount of the organolithium initiator may be selected according to the molecular weight of the desired polymer. Preferably, the organolithium initiator is used in an amount such that the number average molecular weight of the polymer obtained in the second polymerization reaction of step (d) is in the range of 50000-120000, preferably in the range of 60000-100000.

Methods for determining the amount of initiator to be used based on the molecular weight of the polymer to be expected are well known to those skilled in the art and will not be described in detail herein.

In the step (a), the organic lithium initiator is added to the polymerization system in the form of a solution, and the solvent of the organic lithium initiator may be one or more selected from hexane, cyclohexane and heptane, and the concentration is preferably 0.5 to 2mol/L, more preferably 0.8 to 1.5 mol/L.

In the step (b), a retarder is added to the mixture obtained by the initiation reaction to carry out the first polymerization reaction. The retarder is one or more selected from metal alkyl compounds, preferably one or more selected from organic aluminum compounds, organic magnesium compounds and organic zinc compounds.

The organic aluminum compound can be one or more than two of the compounds shown in the formula IV,

in the formula IV, R₄、R₅And R₆Are the same or different and are each independently selected from C₁-C₈Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, hexyl (including various isomers of hexyl), heptyl (including various isomers of heptyl), or octyl (including various isomers of octyl).

Specific examples of the organoaluminum compound may include, but are not limited to, one or two or more of trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, and triisobutylaluminum. Preferably, the organoaluminum compound is triethylaluminum and/or triisobutylaluminum.

The organic magnesium compound can be one or the combination of more than two of the compounds shown in the formula V,

R₈-Mg-R₇(formula V).

In the formula V, R₇And R₈Are the same or different and are each independently selected from C₁-C₈Alkyl of (2), such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentylHexyl (including the various isomers of hexyl), heptyl (including the various isomers of heptyl), or octyl (including the various isomers of octyl).

Specific examples of the organomagnesium compound may include, but are not limited to, one or two or more of di-n-butylmagnesium, di-sec-butylmagnesium, di-isobutylmagnesium, di-tert-butylmagnesium, di-n-sec-butylmagnesium, and n-butyl-sec-butylmagnesium. Preferably, the organomagnesium compound is n-butyl-sec-butylmagnesium.

The organozinc compound can be a compound of formula VI,

R₁₀-Zn-R₉(formula VI)

In the formula VI, R₉And R₁₀Are the same or different and are each independently selected from C₁-C₈Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, hexyl (including various isomers of hexyl), heptyl (including various isomers of heptyl), or octyl (including various isomers of octyl).

Specific examples of the organozinc compound may include, but are not limited to, one or two or more of diethylzinc, dipropylzinc, di-n-butylzinc, di-sec-butylzinc, diisobutylzinc, and di-tert-butylzinc. Preferably, the organozinc compound is diethyl zinc and/or di-n-butyl zinc.

Preferably, the retarder is an organoaluminum compound and/or an organomagnesium compound. More preferably, the retarder is one or more of triethylaluminum, triisobutylaluminum and n-butyl-sec-butylmagnesium.

The amount of the retarder may be selected according to the kind of the retarder.

In one embodiment, the retarder is an organoaluminum compound, and the molar ratio of the organoaluminum compound to the organolithium initiator can be from 0.6 to 0.95: 1, preferably 0.7 to 0.9: 1, the organic aluminum compound is calculated by aluminum element, and the organic lithium initiator is calculated by lithium element.

In another embodiment, the retarder is an organomagnesium compound, and the molar ratio of the organomagnesium compound to the organolithium initiator can be from 1 to 6: 1, preferably 2 to 4: the organic magnesium compound is calculated by magnesium element, and the organic lithium initiator is calculated by lithium element.

In yet another embodiment, the retarder is an organoaluminum compound and an organomagnesium compound, and the molar ratio of the organoaluminum compound, the organomagnesium compound, and the organolithium initiator can be from 0.5 to 2: 1-5: 1, preferably 0.8 to 1: 1.5-3: the organic aluminum compound is calculated by aluminum element, the organic magnesium compound is calculated by magnesium element, and the organic lithium initiator is calculated by lithium element.

In yet another embodiment, the retarder is an organozinc compound, and the molar ratio of organozinc compound to organolithium initiator may be 1-6: 1, preferably 2 to 4: the organic zinc compound is calculated by zinc element, and the organic lithium initiator is calculated by lithium element.

In step (b), the first polymerization reaction may be carried out under conventional anionic polymerization conditions. Generally, the conditions of the first polymerization reaction include: the temperature can be 60-150 deg.C, preferably 80-120 deg.C, and the time can be 60-150min, preferably 70-120 min.

In the step (c), the mixture obtained in the first polymerization reaction is mixed with a second portion of butadiene to carry out a second polymerization reaction.

According to the preparation method of the present invention, the content of the second portion of butadiene may be 5 to 60% by weight, preferably 7 to 50% by weight, and more preferably 10 to 45% by weight, based on the total amount of butadiene.

According to the preparation method of the present invention, preferably, the conditions of the second polymerization reaction include: the temperature can be 60-150 deg.C, preferably 80-100 deg.C, and the time can be 40-120min, preferably 50-100 min.

In step (d), the mixture obtained from the second polymerization reaction in step (c) is coupled by using a coupling agent to bond a part of polymer chains to form a multi-arm star polymer, so that the molecular weight of the prepared butadiene-isoprene copolymer is in a bimodal distribution. Specific examples of the coupling agent may include, but are not limited to, one or more of silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, 1, 8-dibromooctane, gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, and N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane. Preferably, the coupling agent is silicon tetrachloride and/or methyltrichlorosilane.

The amount of the coupling agent used may be selected based on the amount of multi-arm star polymer that is expected to be incorporated in the butadiene-isoprene copolymer. Preferably, the coupling agent is used in an amount such that the molecular weight of the finally prepared butadiene-isoprene copolymer is bimodal, the number average molecular weight of the high molecular weight component (i.e., the polymer component formed by coupling) in the bimodal is in the range of 160000-380000, preferably in the range of 190000-320000, and the content of the high molecular weight component (which may also be referred to as coupling efficiency) is in the range of 50-95 wt%, preferably 55-92 wt%, more preferably 60-90 wt%.

The amount of coupling agent used may be determined based on the desired coupling efficiency. Generally, the molar ratio of coupling agent to organolithium initiator may be from 0.13 to 0.35: 1, more preferably 0.16 to 0.33: 1, more preferably 0.17 to 0.3: 1, more preferably 0.17 to 0.25: 1, the organolithium initiator refers to the amount of the organolithium initiator used to initiate the reaction in step (a), and does not include the portion of the organolithium initiator used to add impurities for removing the reaction system prior to adding the polymerization monomer. The coupling agent may be added to the polymerization system in the form of a solution, and the solvent for dissolving the coupling agent may be, for example, one or two or more selected from hexane, cyclohexane, heptane and the like, and the concentration of the coupling agent is preferably 0.05 to 1mol/L, more preferably 0.1 to 0.5mol/L, and further preferably 0.1 to 0.2 mol/L.

In step (d), the coupling reaction may be carried out under conventional conditions. Generally, the conditions of the coupling reaction include: the temperature may be 60-100 deg.C, preferably 70-90 deg.C, and the time may be 60-100 minutes, preferably 80-100 minutes.

According to the process of the invention, in step (e), the coupling reaction is carried outThe mixture of (a) is contacted with a terminating agent to terminate, thereby inactivating the living chains. The terminator may be, for example, C₁-C₄Preferably one or more of isopropanol, stearic acid, citric acid and carbon dioxide, more preferably carbon dioxide.

In a preferred embodiment, step (e) comprises: and carrying out contact reaction on the mixture obtained by the coupling reaction and carbon dioxide. The carbon dioxide is adopted for termination reaction, and the carbon dioxide can form carbonate with metal ions (Li, Mg, Al, Fe and Zn) in a polymerization system, so that the color development reaction of the metal ions is avoided, and the product has lower chroma. The carbon dioxide herein may be introduced into the reaction system in the form of a gas (for example, carbon dioxide gas having a gauge pressure of 0.2 to 1MPa (for example, 0.3 to 0.6MPa) or may be introduced into the reaction system in the form of an aqueous dry ice solution (for example, having a concentration of 0.5 to 2.0 mol/L).

In this preferred embodiment, the conditions for terminating the reaction include: the temperature is 50-80 deg.C, and the time is 10-40 min.

According to the preparation method of the present invention, the polymerization solution obtained by terminating the reaction in step (e) may be directly discharged without solvent removal treatment or used in a subsequent process, for example, may be directly used as a toughening agent for bulk preparation of aromatic vinyl resins. According to the specific situation, the polymerization solution obtained by terminating the reaction in step (e) may be subjected to a solvent removal treatment, for example, by evaporating a part of the solvent, so as to satisfy the requirements of the subsequent steps. The polymerization solution obtained by terminating the reaction in step (e) may be subjected to solvent removal by a conventional method such as coagulation, and subjected to extrusion granulation by an extruder (e.g., a twin-screw extruder) to obtain the corresponding polymer pellets.

In a preferred embodiment, the preparation method according to the present invention does not include the step of subjecting the polymerization solution containing the butadiene-isoprene copolymer obtained in the step (e) to solvent removal, but directly uses the mixture obtained by terminating the reaction in the step (e) as a toughening agent for the aromatic vinyl resin.

According to the preparation method, alkylbenzene is used as a polymerization solvent, and a retarder is introduced in the polymerization reaction process, so that the molecular weight distribution of the prepared butadiene-isoprene copolymer can be effectively broadened. The butadiene-isoprene copolymer obtained by the preparation method of the invention not only has wide total molecular weight distribution, generally 1.9-2.5, but also has wide molecular weight distribution of low molecular weight component and high molecular weight component in double peak, and the molecular weight distribution can be 1.6-2.1 respectively. Meanwhile, the preparation method of the present invention can greatly reduce the gel content of the prepared polymer, and the gel content of the prepared butadiene-isoprene copolymer is less than 20ppm by mass content. The butadiene-isoprene copolymer produced by the production method of the present invention is particularly suitable for producing an aromatic vinyl resin having a higher impact strength, such as high impact polystyrene (i.e., HIPS resin).

According to a third aspect of the present invention, there is provided a polymerization solution containing a butadiene-isoprene copolymer prepared by the method according to the second aspect of the present invention.

In the present invention, "a structural unit derived from an aromatic vinyl monomer" means that the structural unit is formed from an aromatic vinyl monomer, and the atomic species and the number of each atom are the same as compared with the aromatic vinyl monomer except that the electronic structure is changed; "structural unit derived from a toughening agent" means that the structural unit is formed from the toughening agent and that the atomic species and number of atoms are the same as compared to the toughening agent except for the change in electronic structure.

The aromatic vinyl monomer refers to a monomer having both an aromatic group (e.g., phenyl group) and a vinyl group in the molecular structure. Specific examples of the aromatic vinyl monomer may include, but are not limited to: one or the combination of more than two of styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene and vinylnaphthalene. Preferably, the aromatic vinyl monomer is styrene.

The aromatic vinyl resin may contain only a structural unit derived from an aromatic vinyl monomer and a structural unit derived from a toughening agent, and may also contain a structural unit formed by polymerization of other vinyl monomers. Specific examples of other vinyl monomers may include, but are not limited to: one or more of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile and maleic acid.

The total amount of the toughening agent may be conventionally selected, and preferably, the content of the toughening agent may be 2 to 25% by weight, preferably 5 to 20% by weight, based on the total amount of the aromatic vinyl resin. The amount of the toughening agent may also be optimized according to the type of the aromatic vinyl resin.

In a preferred embodiment, the aromatic vinyl resin contains only structural units derived from an aromatic vinyl monomer and structural units derived from a toughening agent, and a preferred example of the corresponding aromatic vinyl resin is high impact polystyrene. The content of styrene structural units may be 80 to 95 wt%, preferably 85 to 93 wt%, and more preferably 88 to 92 wt%, and the content of butadiene structural units may be 5 to 20 wt%, preferably 7 to 15 wt%, and more preferably 8 to 12 wt%, based on the total amount of the high impact polystyrene. The high impact polystyrene may have a weight average molecular weight of 15 to 35 ten thousand, preferably 16 to 32 ten thousand, more preferably 17 to 30 ten thousand, and a molecular weight distribution index of 1.8 to 3.8, preferably 2 to 3.5, more preferably 2.5 to 3.3.

The high impact polystyrene according to the preferred embodiment has high impact properties and may have an Izod impact strength of 15kJ/m²Above, even 18kJ/m²The above; the present invention will be described in detail below by way of examples.

According to the method for preparing the aromatic vinyl resin of the present invention, specific examples of the aromatic vinyl monomer may include, but are not limited to: one or the combination of more than two of styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene and vinylnaphthalene. Preferably, the aromatic vinyl monomer is styrene.

The polymerized monomer may contain other vinyl monomers in addition to the aromatic vinyl monomer, and specific examples of the other vinyl monomers may include, but are not limited to: one or more of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile and maleic acid.

In a preferred embodiment, the aromatic vinyl monomer is styrene and the final aromatic vinyl resin produced is high impact polystyrene.

According to the method for preparing an aromatic vinyl resin of the present invention, the polymerization reaction may be carried out by a radical polymerization method. The type of the radical initiator used in the radical polymerization is not particularly limited, and may be selected conventionally, and may be one or two or more kinds of thermal decomposition type radical initiators, for example. Preferably, the radical initiator is one or more than two of a peroxide type initiator and an azobisnitrile type initiator. Specific examples of the radical initiator may include, but are not limited to: one or more of diacyl peroxide, peroxy-2-ethylhexyl tert-butyl carbonate, peroxydicarbonate, peroxycarboxylate, alkyl peroxide and azobisnitrile compounds (such as azobisisobutyronitrile and azobisisoheptonitrile). Preferably, the free radical initiator is one or more than two of dibenzoyl peroxide, di-o-methylbenzoyl peroxide, tert-butyl peroxybenzoate and tert-butyl peroxy-2-ethylhexylcarbonate.

The amount of the radical initiator to be used may be conventionally selected so as to be able to obtain an aromatic vinyl resin having a desired molecular weight. Methods for determining the amount of initiator to be used based on the molecular weight of the polymer to be expected are well known to those skilled in the art and will not be described in detail herein.

According to the method for preparing an aromatic vinyl resin of the present invention, the polymerization reaction can be carried out under conventional conditions. Generally, the conditions of the polymerization reaction include: the temperature is 100-155 deg.C (e.g. 100-150 deg.C), and the time is 4-12 hr (e.g. 7-9 hr).

In a preferred embodiment, the polymerization conditions include: the polymerization conditions include: firstly reacting at the temperature of 100-110 ℃ for 1-3h, then reacting at the temperature of 120-130 ℃ for 1-3h, then reacting at the temperature of 140-150 ℃ for 1-3h, and finally reacting at the temperature of 160-170 ℃ for 1-3 h. The polymerization reaction may be carried out with stirring, for example, with stirring at 100-400 rpm.

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

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

(1) Molecular weight and molecular weight distribution index

The measurement is carried out by adopting a HLC-8320 type gel permeation chromatograph of Tosoh corporation in Japan, and the gel permeation chromatograph is provided with TSKgel SuperMultiporeHZ-N and TSKgel SuperMultiporeHZ standard columns, the solvent is chromatographic pure THF, and narrow-distribution polystyrene is used as a standard sample.

The method for testing the molecular weight and the molecular weight distribution index of the butadiene-isoprene copolymer comprises the following steps: the solvent is chromatographic pure tetrahydrofuran, narrow-distribution polystyrene is used as a standard sample, a polymer sample is prepared into a tetrahydrofuran solution with the mass concentration of 1mg/mL, the sample injection amount is 10.00 mu L, the flow rate is 0.35mL/min, and the test temperature is 40.0 ℃.

The molecular weight distribution index of the butadiene-isoprene copolymer is the total molecular weight distribution index of the copolymer, i.e., the molecular weight distribution index measured on a bimodal basis; the molecular weight distribution index of the high molecular weight component in the double peak is a molecular weight distribution index calculated based on the elution peak corresponding to the high molecular weight component, and the molecular weight distribution index of the low molecular weight component in the double peak is a molecular weight distribution index calculated based on the elution peak corresponding to the low molecular weight component; the content of the high molecular weight component refers to the percentage value of the peak area of the bimodal peak corresponding to the eluting peak of the high molecular weight component to the total peak area of the bimodal peak.

The HIPS resin has the following molecular weight and molecular weight distribution index test modes: HIPS resin is dissolved in toluene and centrifugally separated, the supernatant is condensed by ethanol, and then dissolved in THF to prepare a solution with the concentration of 1mg/mL, the THF is used as a mobile phase, and the test temperature is 40 ℃.

(2) A microstructure of a polymer comprising: the content of each structural unit and the content of unsaturated side groups.

The method adopts an AVANCEDRX400MHz type nuclear magnetic resonance instrument produced by BRUKER for measurement, and adopts deuterated chloroform as a solvent and tetramethylsilicon as an internal standard during the test.

(3) Mooney viscosity

Mooney viscosity was measured by a Mooney viscometer model SMV-201SK-160 manufactured by Shimadzu corporation of Japan according to a method specified in the Chinese national Standard GB/T1232-92, in the following manner: ML (1+4), test temperature 100 ℃.

(4) Gel content

The gel content was determined gravimetrically. The specific process is as follows: adding a polymer sample into styrene, shaking the mixture in a shaker at the temperature of 25 ℃ for 16 hours to completely dissolve soluble substances, preparing a styrene solution containing 5 weight percent of polymer, and recording the mass of the polymer sample as C (in grams); weighing a 360-mesh clean nickel screen, and recording the mass of the clean nickel screen as B (in grams); then filtering the solution by using a nickel screen; washing the nickel screen with styrene after filtering, drying the nickel screen for 30 minutes at 150 ℃ under normal pressure, weighing, and recording the mass of the nickel screen as A (in grams); the gel content was calculated according to the following formula:

gel content [ (% a-B)/C ] × 100%.

(5) Impact strength

Notched Izod impact Strength (in kJ/m) as specified in the Chinese national Standard GB/T1843-1996²Meter) test method, the dimensions of the used sample are 80mm × 10mm × 4 mm.

Example 1

This example serves to illustrate the invention.

(1) 300g of ethylbenzene, 70g of butadiene and 80g of isoprene were mixed, and 3.2mL of a hexane solution of n-butyllithium (1.0mol/L, the same applies hereinafter) was added at 40 ℃ to react for 3 min; then 2.7mL of a toluene solution of triisobutylaluminum (1.0mol/L, the same applies below) was added and reacted at 90 ℃ for 120 min; then adding 50g of butadiene, and continuing to react for 60min at 90 ℃; then 3.6mL of hexane solution of silicon tetrachloride (0.2mol/L, the same applies below) is added to carry out coupling reaction for 90min at the temperature of 80 ℃; introducing carbon dioxide gas into the reaction system at 60 deg.C under 0.3MPa for 15 min; stopping introducing carbon dioxide, and obtaining a reaction solution, namely an ethylbenzene polymerization solution A1 (the polymer concentration is 40 weight percent) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with number average molecular weight of 66000 accounted for 12 wt%, the molecular weight distribution index was 1.81, the fraction with number average molecular weight of 211000 accounted for 88 wt%, the molecular weight distribution index was 1.87, the content of isoprene structural units was about 40 wt%, the content of butadiene structural units was about 60 wt%, the content of unsaturated side groups was 12.8 wt%, and the branching area was 88%; the gel content of the copolymer was 1ppm, and the molecular weight distribution index of the copolymer was 2.14; the copolymer Mooney viscosity was 76.

(2)30g of solution A1 (as toughener), 170g of styrene and 0.02g of tert-butyl peroxy-2-ethylhexyl carbonate were mixed and polymerized at 110 ℃ for 2h at a stirring speed of 300rpm, and then heated to 130 ℃ for 3 h; heating to 150 ℃ at the stirring speed of 100rpm, polymerizing for 2h, finally heating to 170 ℃ and polymerizing for 1h, and carrying out vacuum flash evaporation on the reaction product to remove unreacted monomers and solvent to obtain the HIPS resin P1.

Wherein, in the resin, the content of the butadiene structural unit is about 4.7 weight percent, the content of the isoprene structural unit is about 3.2 weight percent, the content of the styrene structural unit is about 92.1 weight percent, the weight-average molecular weight is 264000g/mol, and the molecular weight distribution index is 2.48; the Izod impact strength of the HIPS resin was 18.7kJ/m²。

Example 2

This example serves to illustrate the invention.

(1) Mixing 300g of ethylbenzene, 100g of butadiene and 80g of isoprene, and adding 2.3mL of n-butyllithium in hexane at 50 ℃ to react for 4 min; then adding 1.8mL of toluene solution of triisobutylaluminum and reacting for 90min at 100 ℃; then adding 20g of butadiene, and continuing to react for 60min at 100 ℃; then 2mL of hexane solution of silicon tetrachloride is added to carry out coupling reaction for 90min at the temperature of 80 ℃; introducing carbon dioxide gas into the reaction system at 60 deg.C under 0.5MPa for 10 min; stopping introducing carbon dioxide, and obtaining a reaction solution, namely an ethylbenzene polymerization solution A2 (the polymer concentration is 40 weight percent) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 94000 accounted for 36 wt.%, the molecular weight distribution index was 1.89, the fraction with a number average molecular weight of 301000 accounted for 64 wt.%, the molecular weight distribution index was 1.94, the content of isoprene structural units was about 40 wt.%, the content of butadiene structural units was about 60 wt.%, the content of unsaturated side groups was 13.6 wt.%, and the branching area was 64%; the gel content of the copolymer was 3ppm, and the molecular weight distribution index of the copolymer was 2.39; the copolymer Mooney viscosity was 83.

(2) 35g of solution A2 (as toughener), 170g of styrene and 0.02g of tert-butyl peroxy-2-ethylhexyl carbonate were mixed and polymerized at 110 ℃ for 2h at a stirring speed of 300rpm, and then heated to 130 ℃ for 3 h; heating to 150 ℃ at the stirring speed of 100rpm, polymerizing for 2h, finally heating to 170 ℃ and polymerizing for 1h, and carrying out vacuum flash evaporation on the reaction product to remove unreacted monomers and solvent to obtain the HIPS resin P2.

Wherein, in the resin, the content of the butadiene structural unit is about 5.6 weight percent, the content of the isoprene structural unit is about 3.7 weight percent, the content of the styrene structural unit is about 90.7 weight percent, the weight-average molecular weight is 242000g/mol, and the molecular weight distribution index is 2.64; the Izod impact strength of the HIPS resin was 19.6kJ/m²。

Example 3

This example serves to illustrate the invention.

(1) Mixing 250g of ethylbenzene, 115g of butadiene and 125g of isoprene, and adding 3.3mL of n-butyllithium in hexane at 40 ℃ for reaction for 3 min; then 7mL of toluene solution of diethyl zinc reacts for 120min at 90 ℃; then adding 10g of butadiene, and continuing to react for 100min at 90 ℃; then 3.1mL of hexane solution of silicon tetrachloride is added to carry out coupling reaction for 100min at the temperature of 75 ℃; introducing carbon dioxide gas into the reaction system at 70 deg.C under 0.3MPa for 20 min; stopping introducing carbon dioxide, and obtaining a reaction solution, namely an ethylbenzene polymerization solution A3 (the polymer concentration is 50 weight percent) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 81000 accounted for 23 wt%, the molecular weight distribution index was 1.85, the fraction with a number average molecular weight of 259000 accounted for 77 wt%, the molecular weight distribution index was 1.92, the content of isoprene structural units was about 50 wt%, the content of butadiene structural units was about 50 wt%, the content of unsaturated side groups was 13.1 wt%, and the branching area was 77%; the gel content of the copolymer was 2ppm, and the molecular weight distribution index of the copolymer was 2.26; the copolymer Mooney viscosity was 79.

(2)30g of solution A3 (as toughening agent), 170g of styrene and 0.02g of dibenzoyl peroxide were combined and polymerized at 105 ℃ for 2h at a stirring speed of 300rpm, and then heated to 120 ℃ for 3 h; heating to 150 ℃ under the stirring speed of 100rpm, polymerizing for 1.5h, finally heating to 160 ℃ for polymerizing for 2h, and carrying out vacuum flash evaporation on the reaction product to remove unreacted monomers and solvent to obtain the HIPS resin P3.

Wherein in the resin, a butadiene structural unitAbout 5% by weight, the content of isoprene structural units is about 5% by weight, the content of styrene structural units is about 90% by weight, the weight average molecular weight is 216000g/mol, and the molecular weight distribution index is 2.61; the Izod impact strength of the HIPS resin was 21.8kJ/m²。

Example 4

This example serves to illustrate the invention.

(1) 300g of p-xylene, 100g of butadiene and 50g of isoprene were mixed and reacted at 40 ℃ with 3.8mL of a hexane solution of n-butyllithium for 3 min; then adding 3.2mL of toluene solution of triisobutylaluminum and reacting for 120min at 90 ℃; then adding 50g of butadiene, and continuing to react for 60min at 90 ℃; then 5.5mL of methyl trichlorosilane hexane solution (0.2mol/L) is added to carry out coupling reaction for 80min at the temperature of 80 ℃; introducing carbon dioxide gas into the reaction system at 60 deg.C under 0.3MPa for 15 min; stopping introducing the carbon dioxide, and obtaining a reaction solution, namely a paraxylene polymerization solution A4 (the polymer concentration is 40 weight percent) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 54000 accounted for 18 wt%, the molecular weight distribution index was 1.91, the fraction with a number average molecular weight of 141000 accounted for 82 wt%, the molecular weight distribution index was 1.96, the content of isoprene structural units was about 25 wt%, the content of butadiene structural units was about 75 wt%, the content of unsaturated side groups was 12.9 wt%, and the branching area was 82%; the gel content of the copolymer was 4ppm, and the molecular weight distribution index of the copolymer was 2.21; the copolymer Mooney viscosity was 61.

(2)30g of solution A4 (as toughener), 170g of styrene and 0.02g of tert-butyl peroxy-2-ethylhexyl carbonate were mixed and polymerized at 110 ℃ for 2h at a stirring speed of 300rpm, and then heated to 130 ℃ for 3 h; heating to 150 ℃ at the stirring speed of 100rpm, polymerizing for 2h, finally heating to 170 ℃ and polymerizing for 1h, and carrying out vacuum flash evaporation on the reaction product to remove unreacted monomers and solvent to obtain the HIPS resin P4.

Wherein in the resin, the structural unit of butadieneAbout 6.1% by weight, about 2% by weight of isoprene structural units, about 91.9% by weight of styrene structural units, a weight average molecular weight of 257000g/mol, and a molecular weight distribution index of 2.71; the Izod impact strength of the HIPS resin was 15.8kJ/m²。

Example 5

This example serves to illustrate the invention.

(1) Mixing 250g of ethylbenzene, 60g of butadiene and 180g of isoprene, and adding 2.5mL of n-butyllithium in hexane at 40 ℃ to react for 3 min; then adding 2mL of toluene solution of triisobutylaluminum and reacting for 90min at 100 ℃; then adding 10g of butadiene, and continuing to react for 60min at 90 ℃; then 2.1mL of hexane solution of silicon tetrachloride is added to carry out coupling reaction for 90min at the temperature of 80 ℃; introducing carbon dioxide gas into the reaction system at 60 deg.C under 0.3MPa for 15 min; stopping introducing carbon dioxide, and obtaining a reaction solution, namely an ethylbenzene polymerization solution A5 (the polymer concentration is 50 weight percent) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 109000 accounted for 44 wt%, the molecular weight distribution index was 1.91, the fraction with a number average molecular weight of 349000 accounted for 56 wt%, the molecular weight distribution index was 1.96, the content of isoprene structural units was about 72 wt%, the content of butadiene structural units was about 28 wt%, the content of unsaturated side groups was 13.1 wt%, and the branching area was 63%; the gel content of the copolymer was 4ppm, and the molecular weight distribution index of the copolymer was 2.48; the copolymer Mooney viscosity was 87.

(2) 22g of solution A5 (as toughener), 170g of styrene and 0.02g of tert-butyl peroxy-2-ethylhexyl carbonate were mixed and polymerized at 110 ℃ for 2h at a stirring speed of 300rpm, and then heated to 130 ℃ for 3 h; heating to 150 ℃ at the stirring speed of 100rpm, polymerizing for 2h, finally heating to 170 ℃ and polymerizing for 1h, and carrying out vacuum flash evaporation on the reaction product to remove unreacted monomers and solvent to obtain the HIPS resin P5.

Wherein the resin has a butadiene structural unit content of about 3 wt%, andthe content of pentadiene structural units was about 4.5 weight percent, the content of styrene structural units was about 92.5 weight percent, the weight average molecular weight was 239000g/mol, and the molecular weight distribution index was 2.44; the Izod impact strength of the HIPS resin was 15.2kJ/m²。

Comparative example 1

The process as described in example 1, except that 300g of ethylbenzene and 200g of butadiene were mixed as a raw material instead of the mixture of 300g of ethylbenzene, 70g of butadiene and 120g of isoprene, and the second portion of butadiene addition was removed, but the entire polymerization time was delayed to 3 hours before the coupling agent was added, and the reaction solution obtained after the final termination was the ethylbenzene polymerization solution DA1 (polymer concentration of 40% by weight) of polybutadiene; the molecular weight of polybutadiene in the solution was bimodal, with 11 wt% of the fraction with a number average molecular weight of 67000, a molecular weight distribution index of 1.78, 89 wt% of the fraction with a number average molecular weight of 215000, and a molecular weight distribution index of 1.86; the gel content of the copolymer was 2ppm, and the molecular weight distribution index of the copolymer was 2.06; the copolymer Mooney viscosity was 71.

The toughening agent adopts DA1 to replace A1; thus, HIPS resin DP1 was finally obtained. In the resin, the content of a butadiene structural unit is about 7.2 weight percent, the content of a styrene structural unit is about 92.8 weight percent, the weight average molecular weight is 227000g/mol, and the molecular weight distribution index is 2.78; the Izod impact strength of the HIPS resin was 14.2kJ/m²。

Comparative example 2

According to the method described in example 1, except that 300g of ethylbenzene, 120g of butadiene and 80g of isoprene were mixed as a starting material, instead of adding butadiene in two portions, i.e., a step of removing the second portion of butadiene addition, the entire polymerization time was delayed to 3 hours before the coupling agent was added, and the reaction solution obtained after the final termination was the ethylbenzene polymerization solution DA2 (polymer concentration 40 wt%) of butadiene-isoprene copolymer; the molecular weight of the butadiene-isoprene copolymer in the solution was bimodal, wherein the fraction having a number average molecular weight of 67000 accounted for 44 wt%, the molecular weight distribution index was 1.84, the fraction having a number average molecular weight of 215000 accounted for 56 wt%, the molecular weight distribution index was 1.91, the content of isoprene structural units was about 60 wt%, and the content of butadiene structural units was about 40 wt%; the gel content of the copolymer was 1ppm, and the molecular weight distribution index of the copolymer was 2.39; the copolymer Mooney viscosity was 59.

The toughening agent adopts DA2 to replace A1; thus, HIPS resin DP2 was finally obtained. In the resin, the content of a butadiene structural unit was about 3% by weight, the content of an isoprene structural unit was about 4.6% by weight, the content of a styrene structural unit was about 92.4% by weight, the weight average molecular weight was 288000, and the molecular weight distribution index was 2.64; the Izod impact strength of the HIPS resin was 13.9kJ/m²。

Comparative example 3

According to the method described in example 1, except that in the step (1), the amount of n-butyllithium n-hexane solution is 5mL, the amount of triisobutylaluminum n-hexane solution is 4.3mL, and the amount of silicon tetrachloride n-hexane solution is 5.3mL, the obtained reaction solution is the ethylbenzene polymerization solution DA3 (polymer concentration is 40 wt%) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in this solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 42000 accounted for 23 wt%, the molecular weight distribution index was 1.77, the fraction with a number average molecular weight of 135000 accounted for 77 wt%, the molecular weight distribution index was 1.85, the content of isoprene structural units was about 60 wt%, and the content of butadiene structural units was about 40 wt%; the gel content of the copolymer was 5ppm, and the molecular weight distribution index of the copolymer was 2.24; the copolymer Mooney viscosity was 48.

The toughening agent adopts DA3 to replace A1; thus, HIPS resin DP3 was finally obtained. In the resin, the content of a butadiene structural unit was about 3.0% by weight, the content of an isoprene structural unit was about 4.6% by weight, the content of a styrene structural unit was about 92.4% by weight, the weight average molecular weight was 293000g/mol, and the molecular weight distribution index was 2.72; the Izod impact strength of the HIPS resin was 11.8kJ/m²。

Comparative example 4

According to the method described in example 1, except that in the step (1), the amount of n-butyllithium n-hexane solution was 1.5mL, the amount of triisobutylaluminum n-hexane solution was 1.2mL, and the amount of silicon tetrachloride n-hexane solution was 1.5mL, the obtained reaction solution was the ethylbenzene polymerization solution DA3 (polymer concentration was 40 wt%) of the butadiene-isoprene copolymer; the butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 152000 accounted for 61 wt%, the molecular weight distribution index was 1.83, the fraction with a number average molecular weight of 486000 accounted for 39 wt%, the molecular weight distribution index was 1.91, the content of isoprene structural units was about 60 wt%, and the content of butadiene structural units was about 40 wt%; the gel content of the copolymer was 8ppm, and the molecular weight distribution index of the copolymer was 2.53; the copolymer Mooney viscosity was 117.

The toughening agent adopts DA3 to replace A1; thus, HIPS resin DP3 was finally obtained. In the resin, the content of a butadiene structural unit is about 3.3 weight percent, the content of an isoprene structural unit is about 4.8 weight percent, the content of a styrene structural unit is about 91.9 weight percent, the weight average molecular weight is 237000g/mol, and the molecular weight distribution index is 2.68; the HIPS resin has an Izod impact strength of 12.6kJ/m²。

Comparative example 5

The process of example 1 was repeated, except that ethylbenzene was replaced with equal weight of cyclohexane in the step (1), and the obtained reaction solution was a cyclohexane polymerization solution DA4 (polymer concentration: 40% by weight) of butadiene-isoprene copolymer. The butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was bimodal, wherein the fraction with a number average molecular weight of 69000 accounted for 8 wt%, the molecular weight distribution index was 1.32, the fraction with a number average molecular weight of 221000 accounted for 92 wt%, the molecular weight distribution index was 1.37, the content of isoprene structural units was about 39.8 wt%, the content of butadiene structural units was about 60.2 wt%, the content of unsaturated side groups was 12.1 wt%, and the branching area was 92%; the gel content of the copolymer was 23ppm, and the molecular weight distribution index of the copolymer was 1.54; the copolymer Mooney viscosity was 62.

In the step (3), the solvent is removed by condensing DA4 with steam, the plasticator is dried, and then 40% ethylbenzene solution is obtained by dissolving ethylbenzene instead of A1, so that the HIPS resin DP4 is prepared. In the resin, the content of a butadiene structural unit was about 4.5% by weight, the content of an isoprene structural unit was about 3.1% by weight, the content of a styrene structural unit was about 92.4% by weight, the weight average molecular weight was 213000g/mol, and the molecular weight distribution index was 2.86; the HIPS resin has an Izod impact strength of 12.4kJ/m²。

Comparative example 6

According to the method described in example 1, except that, in the step (1), "2.7 mL of a toluene solution of triisobutylaluminum (1.0mol/L, hereinafter the same) was added and reacted at 90 ℃ for 120 min" was not performed, the polymerization rate and the polymerization temperature could not be controlled, the explosive polymerization occurred, and a large amount of gel was generated. The obtained reaction solution was an ethylbenzene polymerization solution DA5 (polymer concentration: 40% by weight) of butadiene-isoprene copolymer. The butadiene-isoprene copolymer in the solution was terminated with a polymerized segment of butadiene, and its molecular weight was trimodal, wherein the fraction with a number average molecular weight of 64000 accounted for 6 wt%, and the molecular weight distribution index was 1.68; the fraction with number average molecular weight of 128000 accounted for 35%, and the molecular weight distribution index was number average molecular weight of 1.71; 205000, a molecular weight distribution index of 1.75, an isoprene structural unit content of about 40.2 wt.%, a butadiene structural unit content of about 59.8 wt.%, an unsaturated side group content of 16.6 wt.% and a branching area of 94%; the gel content of the copolymer was 746ppm, the molecular weight distribution index of the copolymer was 2.98; the copolymer Mooney viscosity was 87.

In the step (3), DA5 was used in place of A1, whereby HIPS resin DP5 was obtained. The resin had a butadiene structural unit content of about 3.8 wt%, an isoprene structural unit content of about 2.5 wt%, a styrene structural unit content of about 93.7 wt%, a weight average molecular weight of 197000g/mol, and a molecular weight distribution index of 2.77; the Izod impact strength of the HIPS resin was 10.9kJ/m²。

Reference example 1

A control resin was prepared as in step (2) of example 1, i.e., no toughener A1 was used in the preparation of the resin, while the amounts of polymerized monomers and solvent were adjusted to: 184g of styrene, 10g of butadiene, 6g of isoprene and 25g of ethylbenzene, giving a control resin R1. In the resin, the content of a butadiene structural unit was about 4.6% by weight, the content of an isoprene structural unit was about 2.8% by weight, the content of a styrene structural unit was about 92.6% by weight, the weight average molecular weight was 186000g/mol, and the molecular weight distribution index was 3.27; the HIPS resin has an Izod impact strength of 7.4kJ/m²。

The results of examples 1-5 demonstrate that HIPS resins prepared using butadiene-isoprene copolymers according to the present invention as toughening agents have significantly improved impact strength.

The results of examples 1-5 also demonstrate that the polymerization process is controlled and the gel content of the prepared polymer is low when the butadiene-isoprene copolymer is prepared using the method of the present invention, and that HIPS resins prepared using the prepared butadiene-isoprene copolymer as a toughening agent exhibit improved high impact strength; meanwhile, the prepared butadiene-isoprene copolymer does not need to undergo a solvent removal process and a redissolution process, and can be directly used as a toughening agent to be mixed with a polymerization monomer for preparing HIPS resin and then subjected to free radical polymerization reaction, so that the HIPS resin is prepared in situ.

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

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

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

Claims

1. A butadiene-isoprene copolymer, the molecular weight of which is bimodal, the number average molecular weight of the low molecular weight component in the bimodal is in the range of 50000-120000, the molecular weight distribution index is 1.6-2.1, the number average molecular weight of the high molecular weight component in the bimodal is in the range of 160000-380000, the molecular weight distribution index is 1.6-2.1, based on the total amount of the copolymer, the content of the high molecular weight component is 50-95 wt%, the content of butadiene structural units is 20-80 wt%, and the content of isoprene structural units is 20-80 wt%;

the preparation method of the copolymer comprises the following steps:

(e) contacting the mixture obtained by the coupling reaction with a terminating agent for terminating reaction to obtain a polymerization solution containing the butadiene-isoprene copolymer;

the alkylbenzene is used in such an amount that the total concentration of isoprene and butadiene is from 30% by weight to 60% by weight,

the second fraction of butadiene is present in an amount of 5 to 60 wt.%, based on the total amount of butadiene.

2. The copolymer according to claim 1, wherein the high molecular weight component is contained in an amount of 55 to 92% by weight, based on the total amount of the copolymer.

3. The copolymer according to claim 2, wherein the content of the high molecular weight component is 60 to 90% by weight based on the total amount of the copolymer.

4. The copolymer as claimed in any of claims 1 to 3, wherein the number average molecular weight of the low molecular weight component in the bimodal is in the range of 60000-100000 and the molecular weight distribution index is in the range of 1.7-2.0, and the number average molecular weight of the high molecular weight component in the bimodal is in the range of 190000-320000 and the molecular weight distribution index is in the range of 1.7-2.0.

5. The copolymer according to any one of claims 1 to 3, wherein the content of unsaturated side groups in the copolymer is 8 to 20% by weight, based on the total amount of the copolymer.

6. The copolymer according to any one of claims 1 to 3, wherein the copolymer has a molecular weight distribution index of 1.9 to 2.5.

7. The copolymer according to any one of claims 1 to 3, wherein the gel content of the copolymer is less than 20ppm by mass.

8. The copolymer according to any one of claims 1 to 3, wherein the Mooney viscosity of the copolymer is from 50 to 90.

9. A method for preparing a butadiene-isoprene copolymer, comprising the steps of:

10. The method of claim 9, wherein the alkylbenzene is used in an amount such that the total concentration of isoprene and butadiene is from 35 wt% to 55 wt%.

11. The method of claim 10, wherein the alkylbenzene is used in an amount such that the total concentration of isoprene and butadiene is from 40 wt% to 55 wt%.

12. The method of any one of claims 9-11, wherein the alkylbenzene is one or more of toluene, ethylbenzene, and xylene.

13. The method according to any one of claims 9 to 11, wherein in step (a), the time for initiating the reaction is 1-5 min; the temperature of the initiation reaction is 10-50 ℃.

14. The method according to claim 13, wherein in step (a), the time for initiating the reaction is 2-4 min; the temperature of the initiation reaction is 25-40 ℃.

15. The method of claim 14, wherein the temperature at which the reaction is initiated is 30-40 ℃.

16. The method according to any one of claims 9 to 11, wherein the retarder is one or two or more selected from an organoaluminum compound, an organomagnesium compound, and an organozinc compound.

17. The method according to claim 16, wherein the organoaluminum compound is one or two or more compounds represented by formula IV,

in the formula IV, R₄、R₅And R₆Are the same or different and are each independently selected from C₁-C₈Alkyl group of (1).

18. The method according to claim 17, wherein the organoaluminum compound is one or two or more of trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, and triisobutylaluminum.

19. The process according to claim 18, wherein the organoaluminum compound is triethylaluminum and/or triisobutylaluminum.

20. The method according to claim 16, wherein the organomagnesium compound is one or a combination of two or more of the compounds represented by formula V,

R₈-Mg-R₇(formula V)

In the formula V, R₇And R₈Are the same or different and are each independently selected from C₁-C₈Alkyl group of (1).

21. The method according to claim 20, wherein the organomagnesium compound is one or more of di-n-butylmagnesium, di-sec-butylmagnesium, di-isobutylmagnesium, di-tert-butylmagnesium, di-n-sec-butylmagnesium, and n-butyl-sec-butylmagnesium.

22. The method of claim 21, wherein the organomagnesium compound is n-butyl-sec-butylmagnesium.

23. The method of claim 16, wherein the organozinc compound is a compound of formula VI,

R₁₀-Zn-R₉(formula VI)

In the formula VI, R₉And R₁₀Are the same or different and are each independently selected from C₁-C₈Alkyl group of (1).

24. The method according to claim 23, wherein the organozinc compound is one or more of diethylzinc, dipropylzinc, di-n-butylzinc, di-sec-butylzinc, diisobutylzinc, and di-tert-butylzinc.

25. The process of claim 24, wherein the organozinc compound is diethyl zinc and/or di-n-butyl zinc.

26. The process according to claim 16, wherein the retarder is an organoaluminum compound and the organolithium initiator are used in such amounts that the molar ratio of Al element to Li element is from 0.6 to 0.95: 1.

27. the process according to claim 26, wherein the organoaluminum compound and the organolithium initiator are used in amounts such that the molar ratio of Al element to Li element is from 0.7 to 0.9: 1.

28. the method of claim 16, wherein the retarder is an organomagnesium compound and the organolithium initiator are used in amounts such that a molar ratio of Mg element to Li element is 1-6: 1.

29. the process of claim 28, wherein the organomagnesium compound and the organolithium initiator are used in amounts such that a molar ratio of Mg element and Li element is 2-4: 1.

30. the process according to claim 16, wherein the retarder is an organoaluminum compound and an organomagnesium compound, and the organoaluminum compound, the organomagnesium compound and the organolithium initiator are used in amounts such that a molar ratio of an Al element, an Mg element and a Li element is from 0.5 to 2: 1-5: 1.

31. the process according to claim 30, wherein the organoaluminum compound, organomagnesium compound and organolithium initiator are used in amounts such that a molar ratio of Al element, Mg element and Li element is from 0.8 to 1: 1.5-3: 1.

32. the method of claim 16, wherein the retarder is an organozinc compound and the organolithium initiator are used in amounts such that the molar ratio of Zn element to Li element is 1-6: 1.

33. the method of claim 32 wherein the organozinc compound and organolithium initiator are used in amounts such that the molar ratio of Zn element to Li element is from 2 to 4: 1.

34. a process according to any one of claims 9-11, wherein the second fraction of butadiene is present in an amount of 7-50 wt%, based on the total amount of butadiene.

35. The process as claimed in any one of claims 9 to 11, wherein the organolithium initiator is used in an amount such that the number average molecular weight of the copolymer in the mixture obtained by the second polymerization reaction is in the range of 50000-120000.

36. The process as claimed in claim 35, wherein the organolithium initiator is used in an amount such that the number average molecular weight of the copolymer in the mixture obtained by the second polymerization reaction is within the range of 60000-100000.

37. The process according to any one of claims 9 to 11, wherein the coupling agent is used in an amount such that the coupled copolymer content of the mixture resulting from the coupling reaction is from 50 to 95% by weight.

38. The process according to claim 37, wherein the coupling agent is used in an amount such that the coupled copolymer content of the mixture resulting from the coupling reaction is from 55 to 92% by weight.

39. The process according to claim 38, wherein the coupling agent is used in an amount such that the coupled copolymer content of the mixture resulting from the coupling reaction is from 60 to 90% by weight.

40. The method as claimed in claim 37, wherein the degree of the coupling reaction is such that the number average molecular weight of the coupled copolymer in the mixture resulting from the coupling reaction is in the range of 160000-380000.

41. The method as claimed in claim 40, wherein the degree of the coupling reaction is such that the number average molecular weight of the coupled copolymer in the mixture obtained by the coupling reaction is in the range of 190000-320000.

42. The method according to any one of claims 9 to 11, wherein in step (d) the coupling agent is one or more of silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, 1, 8-dibromooctane, gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane and N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane.

43. The method of claim 42, wherein the coupling agent is silicon tetrachloride and/or methyltrichlorosilane.

44. The method of any of claims 9-11, wherein the conditions of the first polymerization reaction comprise: the temperature is 60-150 ℃; the time is 60-150 min;

the conditions of the second polymerization reaction include: the temperature is 60-150 ℃; the time is 40-120 min;

the conditions of the coupling reaction include: the temperature is 60-100 ℃; the time is 60-100 min.

45. The method of claim 44, wherein the conditions of the first polymerization reaction comprise: the temperature is 80-120 ℃; the time is 70-120 min;

the conditions of the second polymerization reaction include: the temperature is 80-100 ℃; the time is 50-100 min;

the conditions of the coupling reaction include: the temperature is 70-90 ℃; the time is 80-100 min.

46. The method according to any one of claims 9 to 11, wherein the method does not comprise a step of subjecting the polymerization solution containing the butadiene-isoprene copolymer obtained in step (e) to solvent removal.

47. A polymerization solution containing a butadiene-isoprene copolymer prepared by the method of any one of claims 9-46.

48. An aromatic vinyl resin comprising a structural unit derived from an aromatic vinyl monomer and a structural unit derived from a toughening agent, wherein the toughening agent is a butadiene-isoprene copolymer;

the molecular weight of the butadiene-isoprene copolymer is in bimodal distribution, the number average molecular weight of a low molecular weight component in the bimodal distribution is in the range of 50000-120000, the molecular weight distribution index is 1.6-2.1, the number average molecular weight of a high molecular weight component in the bimodal distribution is in the range of 160000-380000, the molecular weight distribution index is 1.6-2.1, and based on the total amount of the copolymer, the content of the high molecular weight component is 50-95 wt%, the content of a butadiene structural unit is 20-80 wt%, and the content of an isoprene structural unit is 20-80 wt%.

49. The aromatic vinyl resin according to claim 48, wherein the high molecular weight component is contained in an amount of 55 to 92% by weight based on the total amount of the copolymer.

50. The aromatic vinyl resin according to claim 49, wherein the content of the high molecular weight component is 60 to 90% by weight based on the total amount of the copolymer.

51. The aromatic vinyl resin according to any one of claims 48 to 50, wherein the number average molecular weight of the low molecular weight component in the bimodal ranges from 60000-100000 and the molecular weight distribution index is from 1.7 to 2.0, and the number average molecular weight of the high molecular weight component in the bimodal ranges from 190000-320000 and the molecular weight distribution index is from 1.7 to 2.0.

52. The aromatic vinyl resin according to any one of claims 48 to 50, wherein the content of unsaturated side groups in the copolymer is 8 to 20% by weight based on the total amount of the copolymer.

53. The aromatic vinyl resin according to any one of claims 48 to 50, wherein the copolymer has a molecular weight distribution index of 1.9 to 2.5.

54. The aromatic vinyl resin according to any one of claims 48 to 50, wherein the gel content of the copolymer is less than 20ppm by mass.

55. The aromatic vinyl resin according to any one of claims 48 to 50, wherein the Mooney viscosity of the copolymer is from 50 to 90.

56. The aromatic vinyl resin according to claim 48, wherein the aromatic vinyl resin is a high impact polystyrene resin.

57. A method for preparing an aromatic vinyl resin, comprising: mixing a polymerized monomer containing an aromatic vinyl monomer with a solution containing a toughening agent under a radical polymerization reaction condition, and polymerizing the resultant mixture, wherein the solution containing the toughening agent is the polymerized solution containing the butadiene-isoprene copolymer according to claim 47.

58. The method of claim 57, wherein the aromatic vinyl resin is a high impact polystyrene resin.