Multi-polarity binary structure modifier, and preparation method therefor and use thereof

Abstract

The present invention provides a multi-polarity binary structure modifier, and a preparation method therefor and a use thereof. The multi-polarity binary structure modifier contains a sulfonyl hydroxide group which can fully exert the "polarity effect" of a polyamine group and an epoxy group during anionic polymerization of conjugated diene (1,3-butadiene). In one aspect, the electron supply capability is greatly improved, and the reaction is promoted to move towards a π-allyl lithium structure, and in the other aspect, the degree of association of an initiator is improved. Under the synergistic effect of the two aspects, the 1,2-structure content can be efficiently regulated, so that a high-vinyl low-gel-content polybutadiene liquid rubber can be prepared.

Description

A multipolar binary structure modifier, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 202411523004.8, filed on October 29, 2024, entitled “A Multipolar Binary Structure Regulator and Its Preparation Method and Application”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of organic synthesis technology, and in particular to a multipolar binary structure regulator, its preparation method, and its application. Background Technology

[0003] With the development of modern communication, polybutadiene liquid rubber has gradually begun to be used as an adhesive for circuit boards. Since modern communication signals are transmitted at high frequency and high speed, circuit boards generate a lot of heat during use. This requires that various materials have both heat aging resistance and excellent adhesion, while not damaging the dielectric constant and dielectric loss coefficient of the substrate. In the case of polybutadiene liquid rubber, this means that the content of polymer vinyl structure (1,2-structure) should be high to facilitate curing reaction with other resins, glass fibers, etc. to form a cross-linked structure, thereby improving the overall strength and adhesion of the circuit board.

[0004] However, polybutadiene liquid rubber is a viscous, flowable polymer formed by the polymerization of 1,3-butadiene monomers, resulting in a number-average molecular weight of 500-10,000. Typically, in anionic polymerization, the polymerization of 1,3-butadiene is predominantly trans-1,4-structure polymerization (over 60%), with a low content of 1,2-structure, which cannot meet the high reactivity requirements of advanced electronic materials. To obtain polybutadiene liquid rubber with a high content of vinyl structures (1,2-structure), it is necessary to achieve controllability of the polymer microstructure within a certain range. Many factors influence the polymer microstructure, such as the type and concentration of initiators, the effects of solvents and polar additives, and temperature. Among these factors, adding polar modifiers is one of the most important methods for synthesizing polymers with different microstructures.

[0005] However, the high vinyl content also brings a serious drawback to polybutadiene liquid rubber. As the 1,2 content of polybutadiene liquid rubber increases, numerous active unsaturated double bonds appear on the side chains of its main chain. These bonds readily react to form a three-dimensional network of macromolecules, resulting in gel formation. This leads to a decrease in the overall bonding strength of the circuit board, affecting its quality and lifespan. Therefore, developing high-vinyl, low-gel polybutadiene liquid rubber has broad industrial application value and prospects in the field of electronic communications.

[0006] In the prior art, research on high-vinyl-structure polybutadiene liquid rubber mainly involves the addition of polarity modifiers. CN113461837A provides a method for preparing low-cis, high-vinyl-terminated hydroxyl polybutadiene rubber, which uses a mixture of tetrahydrofuran and N,N-dimethylformamide, a mixture of tetrahydrofuran and tetramethylethylenediamine, a mixture of tetrahydrofuran and 2,2-di(2-tetrahydrofuranyl)propane, or a mixture of 2,2-di(2-tetrahydrofuranyl)propane and tetrahydrofurfuryl ethyl ether as the added structure modifier to prepare the high-vinyl-structure polybutadiene liquid rubber. CN1089272A discloses a method for controlling the vinyl content in butadiene homopolymers and copolymers, using a combination of diethylene glycol dimethyl ether and tetrahydrofuran as modifiers to control the vinyl content in polybutadiene rubber. CN117327219A provides a method for preparing high-vinyl polybutadiene liquid rubber, which uses a structure modifier 2,2-bis(2-tetrahydrofuranyl) to prepare high-vinyl polybutadiene liquid rubber.

[0007] While the use of small-molecule organic structure modifiers can increase the vinyl content in polybutadiene liquid rubber to some extent, these methods still have limitations. These modifiers are mainly produced through compounding, resulting in large fluctuations in vinyl structure, high dosage requirements, high cost, and limited modification effectiveness. Furthermore, they can also lead to problems such as high gelation rates.

[0008] Therefore, developing a method for preparing polybutadiene liquid rubber with high vinyl content and low gel content has become a current research direction. Summary of the Invention

[0009] This invention provides a multipolar binary structure modifier, which has the characteristic of being able to produce high-ethylene-content polybutadiene liquid rubber.

[0010] The present invention also provides a method for preparing a multipolar binary structure modifier, which has the advantage of being relatively simple in preparation process.

[0011] The present invention also provides a polybutadiene liquid rubber, which has the characteristics of high vinyl content and low gel content.

[0012] The present invention also provides a method for preparing polybutadiene liquid rubber, which has the advantages of stable product quality and suitability for industrial production.

[0013] This invention provides a multipolar binary structure modifier, wherein the multipolar binary structure modifier has the structure shown in Formula 1:

[0014] Wherein, R1 is a C1-C4 straight-chain alkyl group, and R2 is a C1-C4 straight-chain alkyl group. 12 Alkyl groups.

[0015] The present invention also provides a method for preparing a multipolar binary structure modifier. The method comprises esterifying 3,5-diamino-4-alkylbenzenesulfonic acid and tetrahydro-2-furanol to obtain the multipolar binary structure modifier.

[0016] The tetrahydro-2-furanol has the structure shown in Formula 2:

[0017] The 3,5-diamino-4-alkylbenzenesulfonic acid has the structure shown in Formula 3:

[0018] Wherein, R1 is a C1-C4 straight-chain alkyl group, and R2 is a C1-C4 straight-chain alkyl group. 12 The alkyl group; preferably R1 is n-propyl or isopropyl, and preferably R2 is methyl.

[0019] The preparation method of the multipolar binary structure modifier as described above, wherein the esterification reaction specifically includes the following steps:

[0020] 3,5-Diamino-4-alkylbenzenesulfonic acid, chlorosulfonic acid and sodium chloride were mixed and subjected to a first heating and stirring reaction to obtain a first heating and stirring reaction system.

[0021] Tetrahydro-2-furanol and sodium hydroxide aqueous solution were added to the first heating and stirring reaction system to carry out a second heating and stirring reaction, thereby obtaining a second heating and stirring reaction system.

[0022] The pH of the second heating and stirring reaction system was adjusted to 6.5–7.5, and separation was performed to obtain the multipolar binary structure regulator.

[0023] The stirring speed of the first heating and stirring reaction is 100-200 rpm, the reaction temperature is 43-52℃, and the reaction time is 1.6-2.4 h;

[0024] The stirring speed of the second heating and stirring reaction is 100-200 rpm, the reaction temperature is 112-130℃, and the reaction time is 2.6-3.5 h.

[0025] In the preparation method of the multipolar binary structure modifier as described above, in the esterification reaction, when the sum of the masses of 3,5-diamino-4-methylbenzenesulfonic acid and tetrahydro-2-furanpropanol is 100, the mass ratio of the two is (30-40):(60-70); and / or,

[0026] In the esterification reaction, the mass ratio of 3,5-diamino-4-methylbenzenesulfonic acid, chlorosulfonic acid, and sodium chloride is 1:(1.5-4.0):(0.01-0.1).

[0027] The present invention also provides a method for preparing polybutadiene liquid rubber, which can be used to obtain any of the above-mentioned polybutadiene liquid rubber. The method includes using the above-mentioned multipolar binary structure modifier and initiator to cause 1,3-butadiene to undergo a polymerization reaction to obtain the polybutadiene liquid rubber.

[0028] The initiator is a hydrocarbon-based monolithium compound;

[0029] The polymerization reaction specifically includes the following steps:

[0030] Solvent, a portion of 1,3-butadiene, and a portion of the multipolar binary structure modifier are added sequentially to the reaction vessel, followed by the addition of a portion of the initiator to initiate the polymerization reaction; during the reaction, the remaining 1,3-butadiene, multipolar binary structure modifier, and initiator are added at least twice.

[0031] The portion of 1,3-butadiene does not exceed 50% of the total mass of 1,3-butadiene;

[0032] The polymerization reaction temperature is -10 to -5℃.

[0033] In the preparation method of polybutadiene liquid rubber as described above, the remaining 1,3-butadiene, multipolar binary structure modifier, and initiator are added at least twice, specifically including:

[0034] When the conversion rate is 14%–17%, add the first component.

[0035] When the conversion rate is 65%–70%, add the second component;

[0036] When the conversion rate is 95% to 96%, a terminator is added to the reaction system to obtain the polybutadiene liquid rubber.

[0037] Both the first component and the second component include 1,3-butadiene, the multipolar binary structure modifier, and the initiator.

[0038] In the method for preparing polybutadiene liquid rubber as described above, the molar ratio of the multipolar binary structure modifier to the initiator in the first and second components is (1.0–7.2):1; and / or,

[0039] The molar ratio of a portion of the multipolar binary structure modifier and a portion of the initiator added to the container for the first time is (1.0 to 7.2):1.

[0040] In the method for preparing polybutadiene liquid rubber as described above, the amount of the initiator is equal to the ratio of the expected mass of the target polybutadiene liquid rubber to the molecular weight of the target polybutadiene liquid rubber.

[0041] The present invention also provides a polybutadiene liquid rubber comprising the above-mentioned multipolar binary structure modifier.

[0042] The polybutadiene liquid rubber described above, wherein the number average molecular weight of the liquid rubber is 3700-4900, and the vinyl content is greater than or equal to 88.6%; and / or,

[0043] The gel content of the liquid rubber is less than or equal to 2.4%.

[0044] The multipolar binary structure modifier provided by this invention has the characteristic of being able to produce polybutadiene liquid rubber with high vinyl content. Attached Figure Description

[0045] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0046] Figure 1 shows the infrared spectrum of the multipolar binary structure modifier prepared in Example 1. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Currently, methods for preparing polybutadiene liquid rubber using small-molecule organic structure modifiers suffer from problems such as large fluctuations in the vinyl structure and high gel content in the product. Based on these phenomena, the inventors speculate that this may be because small-molecule organic structure modifiers are mainly produced through compounding and mixing. These polar reagents with different microstructures exhibit varying degrees of polarity and dispersion, resulting in different effects on altering the association state of the initiator and the active species of the reactive monomers. This inevitably makes it difficult to control the rate of increase in the 1,2-structure content of the conjugated diene, hindering the stability of the polymer product structure and easily leading to large fluctuations in the vinyl structure and high gel content, thus causing the aforementioned defects in the prepared polybutadiene liquid rubber. The inventors, starting with the structure of the structure modifier, have developed a structure modifier with a novel structure. Using this modifier, polybutadiene liquid rubber with high vinyl content and low gel content can be prepared, thereby solving the aforementioned technical problems.

[0049] Based on this, the first aspect of the present invention provides a multipolar binary structure modifier, wherein the multipolar binary structure modifier has the structure shown in Formula 1:

[0050] Formula 1;

[0051] Wherein, R1 is a C1-C4 straight-chain alkyl group, and R2 is a C1-C4 straight-chain alkyl group. 12 Alkyl groups.

[0052] The inventors discovered that polybutadiene liquid rubber with high vinyl content and low gel content can be prepared using the aforementioned multipolar binary structure modifier. Specifically, when 1,3-butadiene undergoes polymerization using the aforementioned polar binary structure modifier, the resulting polybutadiene liquid rubber exhibits high vinyl content. The inventors speculate that the reason for this phenomenon may be that the sulfonic acid groups contained in the multipolar binary structure modifier can fully exert the "polar effect" of polyamine and epoxy groups during the anionic polymerization of conjugated dienes (1,3-butadiene). On the one hand, this greatly enhances the electron-donating ability, promoting the reaction towards the π-allyl lithium structure; on the other hand, it increases the association degree of the initiator. Under the synergistic effect of these two aspects, efficient control of the 1,2-structure content can be achieved, thereby enabling the preparation of high-vinyl polybutadiene liquid rubber with a high vinyl (1,2-structure) content.

[0053] More specifically, this multipolar binary structure regulator has a greater regulating capacity than when the mono-component is used alone. This composite regulating system not only requires a small dosage but is also less affected by the polymerization temperature, enabling precise control of the high vinyl content in polybutadiene liquid rubber. This solves the problems of large fluctuations and poor stability in the 1,2-structure of polybutadiene liquid rubber.

[0054] In a preferred embodiment, R1 is a C1-C4 straight-chain alkyl group, and R2 is a C1-C4 straight-chain alkyl group. 12 Alkyl groups. The selection of R1 and R2 within the above range can minimize the change in glass transition temperature of polybutadiene liquid rubber caused by the increase of vinyl groups in the 1,2-structure, while also minimizing the crystallinity caused by the regular 1,2-structure vinyl sequence.

[0055] The present invention does not limit the preparation method of the above-mentioned multipolar binary structure modifier. Conventional preparation methods in the art can be used, for example, the substance can be prepared by esterification reaction of carboxylic acids and alcohols.

[0056] A second aspect of this invention provides a method for preparing a multipolar binary structure modifier, which can be used to obtain the multipolar binary structure modifier provided in the first aspect of this invention. The method includes esterifying 3,5-diamino-4-alkylbenzenesulfonic acid and tetrahydro-2-furanol to obtain the multipolar binary structure modifier.

[0057] Tetrahydro-2-furanol has the structure shown in Formula 2:

[0058] 3,5-Diamino-4-alkylbenzenesulfonic acid has the structure shown in Formula 3:

[0059] The polar binary structure modifier is an ester, which can be prepared by esterification of the corresponding carboxylic acid and alcohol. The esterification reaction conditions are mild, and the reaction rate is relatively fast, allowing for the faster preparation of the aforementioned polar binary structure modifier, thus making the preparation method provided by this invention more efficient.

[0060] The tetrahydro-2-furanol may be selected from at least one of tetrahydro-2-furanol, tetrahydro-2-furanethanol, tetrahydro-2-furanpropanol, and tetrahydro-2-furanbutanol; the 3,5-diamino-4-alkylbenzenesulfonic acid may be selected from at least one of 3,5-diamino-4-methylbenzenesulfonic acid, 3,5-diamino-4-ethylbenzenesulfonic acid, 3,5-diamino-4-propylbenzenesulfonic acid, 3,5-diamino-4-butylbenzenesulfonic acid, 3,5-diamino-4-isobutylbenzenesulfonic acid, 3,5-diamino-4-hexylbenzenesulfonic acid, 3,5-diamino-4-octylbenzenesulfonic acid, and 3,5-diamino-4-dodecylbenzenesulfonic acid.

[0061] This invention does not limit the specific reaction conditions of the esterification reaction. Commonly used esterification reaction conditions in the art can be used as long as they meet the requirements for obtaining the above-mentioned multipolar binary structure regulator.

[0062] In one embodiment, for tetrahydro-2-furanol, R1 is a C1-C4 straight-chain alkyl group; for 3,5-diamino-4-alkylbenzenesulfonic acid, R2 is a C1-C4 straight-chain alkyl group. 12Alkyl group. In a preferred embodiment, for formula 1, R1 is n-propyl or isopropyl; for formula 2, R2 is methyl. That is, tetrahydro-2-furanol is tetrahydro-2-furanpropanol, and 3,5-diamino-4-alkylbenzenesulfonic acid is 3,5-diamino-4-methylbenzenesulfonic acid. Because the aforementioned substances are polar substances containing heteroatoms (such as oxygen, nitrogen, sulfur, etc.), they are characterized as Lewis bases that supply electrons. Based on the anionic reaction mechanism of conjugated dienes (including 1,3-butadiene and isoprene) proposed by Jin Guantai, Li Tianhu, and others, the active species exist in two structural forms, σ-allyllithium and π-allyllithium, during the polymerization of conjugated dienes. σ-allyllithium mainly forms the 1,4-structure, while π-allyllithium mainly forms the 1,2-structure. These two structures are in thermodynamic equilibrium under the action of polar solvents. As the amount of polar additives increases, the equilibrium shifts towards the π-allyllithium structure, meaning that the 1,2-addition product increases accordingly. Therefore, the resulting polybutadiene liquid rubber has a higher vinyl content.

[0063] To further improve the purity and yield of the multipolar binary structure modifier, the esterification reaction in the preparation method of this structure modifier may specifically include the following steps:

[0064] 3,5-Diamino-4-alkylbenzenesulfonic acid, chlorosulfonic acid and sodium chloride were mixed and subjected to a first heating and stirring reaction to obtain a first heating and stirring reaction system.

[0065] Tetrahydro-2-furanol and sodium hydroxide aqueous solution were added to the first heating and stirring reaction system, and a second heating and stirring reaction was carried out to obtain the second heating and stirring reaction system.

[0066] The pH of the second heating and stirring reaction system was adjusted to 6.5–7.5, and separation was performed to obtain a multipolar binary structure regulator.

[0067] The stirring speed for the first heating and stirring reaction is 100-200 rpm, the reaction temperature is 43-52℃, and the reaction time is 1.6-2.4 h.

[0068] The stirring speed for the second heating and stirring reaction is 100-200 rpm, the reaction temperature is 112-130℃, and the reaction time is 2.6-3.5 h.

[0069] In this process, chlorosulfonic acid catalyzes the esterification reaction, sodium chloride promotes the formation of benzenesulfonyl chloride, and sodium hydroxide aqueous solution catalyzes the reaction between acyl chloride and hydroxyl groups.

[0070] The purpose of the first heating and stirring reaction is to promote the formation of the intermediate benzenesulfonyl chloride;

[0071] The second heating and stirring reaction serves to promote the esterification reaction.

[0072] The molar concentration of the sodium hydroxide aqueous solution is 15.5–17.6 mol / L. The amount of sodium hydroxide solution added conforms to the conventional addition range in the prior art, and is not particularly limited in this invention, but can be adjusted according to the amount of tetrahydro-2-furanpropanol added. In one embodiment, the mass ratio of sodium hydroxide solution to tetrahydro-2-furanpropanol is (0.1–0.5):1; further, in a preferred embodiment, the mass ratio of sodium hydroxide solution to tetrahydro-2-furanpropanol is (0.2–0.3):1.

[0073] This invention does not limit the mass ratio or molar ratio of 3,5-diamino-4-alkylbenzenesulfonic acid and tetrahydro-2-furanol, which can be determined according to the esterification reaction mechanism. For example, the molar ratio of 3,5-diamino-4-alkylbenzenesulfonic acid and tetrahydro-2-furanol is 1:1. Furthermore, either substance can be in excess to promote complete reaction.

[0074] Using esterification reactions with the above characteristics has the advantages of high yield and few side reactions.

[0075] This invention does not limit the specific processing method of the separation process in step 3). Commonly used separation methods in the art can be used, as long as the obtained multipolar binary structure regulator can be separated from the reaction system. In one embodiment, the separation process includes sequentially adjusting the pH of the reaction system to neutral with dilute hydrochloric acid solution, separating the aqueous and oil phases, drying, and distilling. The molar concentration of the dilute hydrochloric acid solution can be selected from 0.5 to 0.8 mol / L.

[0076] To further improve the conversion rate of raw materials, in the esterification reaction, when the total mass of 3,5-diamino-4-methylbenzenesulfonic acid and tetrahydro-2-furanpropanol is 100, the mass ratio of the two can be controlled at (30-40):(60-70). Furthermore, in the esterification reaction, controlling the mass ratio of 3,5-diamino-4-methylbenzenesulfonic acid, chlorosulfonic acid and sodium chloride to 1:(1.5-4.0):(0.01-0.1) can further improve the conversion rate of raw materials.

[0077] The third aspect of the present invention provides a method for preparing polybutadiene liquid rubber, the method comprising using a multipolar binary structure modifier and an initiator provided in the first aspect of the present invention to cause a polymerization reaction of 1,3-butadiene to obtain polybutadiene liquid rubber;

[0078] The initiator is a hydrocarbon-based monolithium compound;

[0079] The polymerization reaction specifically includes the following steps:

[0080] Solvent, a portion of 1,3-butadiene, and a portion of multipolar binary structure modifier are added sequentially to the reaction vessel, followed by the addition of an initiator to begin the polymerization reaction; during the reaction, the remaining 1,3-butadiene, multipolar binary structure modifier, and initiator are added at least twice.

[0081] A portion of the 1,3-butadiene does not exceed 50% of the total mass of the 1,3-butadiene;

[0082] The reaction temperature for polymerization is -10 to -5℃.

[0083] Specifically, in the above reaction process, 1,3-butadiene is not added all at once, but in at least three separate additions. Specifically, the 1,3-butadiene added at the initial stage of the reaction does not exceed 50% of the total mass of 1,3-butadiene, and the remaining 1,3-butadiene is added in at least two additional additions. Correspondingly, the multipolar binary structure modifier and initiator are also added in at least three separate additions, each including 1,3-butadiene, the multipolar binary structure modifier, and the initiator.

[0084] The reaction temperature of the polymerization reaction is -10 to -5℃, which means that the temperature of the reaction system is -10 to -5℃ during the reaction process. Furthermore, it also includes adding solvent, a portion of 1,3-butadiene, and a portion of multipolar binary structure regulator to the reaction vessel in sequence. The mixture is stirred at 600 to 700 rpm while being cooled to -10 to -5℃ before the initiator is added to start the reaction.

[0085] The solvent is a hydrocarbon solvent, specifically including straight-chain alkanes, aromatics and cycloalkanes. This hydrocarbon solvent is selected from one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene, preferably cyclohexane.

[0086] The initiator is a hydrocarbon-based monolithium compound, specifically, the hydrocarbon-based monolithium compound has the structural formula RLi, where R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic group, or a complex group containing 1 to 20 carbon atoms. Specifically, the hydrocarbon-based monolithium compound can be selected from at least one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthium lithium, cyclohexyllithium, and dodecyllithium. In a preferred embodiment, the hydrocarbon-based monolithium compound is n-butyllithium, and the amount of initiator added can be determined by the molecular weight of the target high-content vinyl liquid polybutadiene.

[0087] Furthermore, the 1,3-butadiene is of polymerization grade (purity ≥97%); the terminator can be selected from one or more of methanol, ethanol, propanol, butanol, isobutanol and pentanol, and the amount used is the conventional amount used in the art. The amount added is preferably 2.0 to 7.0 parts based on 100 parts by weight of 1,3-butadiene monomer, more preferably 4.0 to 5.0 parts.

[0088] Furthermore, based on 100 parts by mass of 1,3-butadiene monomer, the mass ratio of solvent, 1,3-butadiene, and terminator is (800-1000):100:(3.0-5.0).

[0089] The inventors discovered that the polybutadiene liquid rubber prepared using the above method has a low gel content. Based on this phenomenon, the inventors speculate that the reason may be that the segmented polymerization achieved by using low temperature (multipolar binary structure regulator and initiator) and multiple additions can control the growth and branching of polybutadiene molecular chains by generating new active centers and reducing the reaction rate, thereby reducing the aggregation of polybutadiene molecular chains and preventing the probability of gel conversion, thus obtaining polybutadiene liquid rubber with a gel content ≤2.4%. Furthermore, the initial addition of 1,3-butadiene should not exceed 50% of the total mass of 1,3-butadiene to prevent the reaction system from generating too much gel due to an excessively fast initial reaction rate.

[0090] This invention does not limit the timing of adding the remaining 1,3-butadiene and the multipolar binary structure modifier, and can be done according to actual needs. In one embodiment, the remaining 1,3-butadiene, the multipolar binary structure modifier, and the initiator can be added in batches when the reaction system has different conversion rates. For example, 1,3-butadiene, the multipolar binary structure modifier, and the initiator can be added for the first time when the conversion rate is 10-30%, and then added for the second time when the conversion rate is 60-80%.

[0091] Understandably, during the addition of 1,3-butadiene and the multipolar binary structure modifier, an initiator can also be added simultaneously to maintain the smooth progress of the reaction.

[0092] The present invention does not limit the total mass ratio of 1,3-butadiene to the multipolar binary structure modifier. In one embodiment, the mass ratio of the two is 100:28-100:4.5.

[0093] The method for preparing polybutadiene liquid rubber provided by this invention uses a multipolar binary structure modifier to control the vinyl content in the product, resulting in stable product quality and suitability for industrial production.

[0094] In a further embodiment, the remaining 1,3-butadiene, the multipolar binary structure modifier, and the initiator are added at least twice, specifically including:

[0095] When the conversion rate is 14%–17%, add the first component.

[0096] When the conversion rate is 65%–70%, add the second component;

[0097] When the conversion rate is 95% to 96%, a terminator is added to the reaction system to obtain polybutadiene liquid rubber;

[0098] Both the first and second components include 1,3-butadiene, a multipolar binary structure modifier, and an initiator.

[0099] The above polymerization reaction achieves segmented polymerization by adding 1,3-butadiene, a multipolar binary structure regulator, and an initiator three times at specific times (specific conversion rates) (one initial addition and two supplementary additions). This multi-stage addition method controls the rapid growth and branching of polybutadiene molecular chains, reduces the aggregation of polybutadiene molecular chains, and lowers the conversion to gel. The resulting polybutadiene liquid rubber has the advantage of lower gel content.

[0100] Furthermore, after adding the terminator, the process includes separating the obtained polybutadiene liquid rubber. Specifically, water and acid are added to the reaction mixture containing polybutadiene, the mixture is stirred and allowed to stand to separate into layers, separating the aqueous phase and the oil phase. The oil phase is then subjected to vacuum distillation to obtain a low-gel, high-vinyl polybutadiene liquid rubber. The types of water and acid used in the above coagulation process are well known to those skilled in the art, and their addition amounts conform to the conventional addition ranges in the prior art; this invention does not impose any particular limitation. For example, the acid can be selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and dilute nitric acid.

[0101] The multipolar binary structure modifier does not participate in the actual copolymerization reaction during the preparation of polybutadiene liquid rubber. In actual industrial production of polybutadiene liquid rubber, the multipolar binary structure modifier can be easily separated from the solvent, and the solvent can be recycled.

[0102] This invention employs a system of hydrocarbon-based monolithium compound initiator and multipolar binary structure modifier to initiate the anionic polymerization of 1,3-butadiene. By rationally setting the component ratios in this system, especially the ratio of multipolar binary structure modifier to hydrocarbon-based monolithium compound, the vinyl content in the polybutadiene structure can be controlled. In specific implementation, the molar ratio of multipolar binary structure modifier to hydrocarbon-based monolithium compound initiator in the first and second components is (1.0–7.2):1, more preferably (2.9–3.7):1, where the hydrocarbon-based monolithium compound initiator is calculated as elemental lithium. In a more preferred embodiment, the molar ratio of a portion of the multipolar binary structure modifier and a portion of the initiator initially added to the container is also (1.0–7.2):1, more preferably (2.9–3.7):1. The first addition of a portion of the multipolar binary structure modifier and a portion of the initiator to the reaction vessel refers to the multipolar binary structure modifier and initiator added sequentially to the reaction vessel at the beginning of the preparation process, as described in the process of "adding solvent, a portion of 1,3-butadiene, a portion of the multipolar binary structure modifier, and then adding a portion of the initiator to start the polymerization reaction".

[0103] In one embodiment, in the method for preparing polybutadiene liquid rubber provided by the present invention, both the esterification reaction and the polymerization reaction are carried out in an oxygen-free, anhydrous, and inert gas environment. The inert gas is nitrogen or a gas of a group 0 element in the periodic table other than radon, preferably argon; the number of replacements is 3 to 5; the reaction vessel can be a loop reactor or a batch reactor, preferably a batch reactor.

[0104] In one embodiment, the amount of initiator is equal to the ratio of the expected prepared mass of the target polybutadiene liquid rubber to the molecular weight of the target polybutadiene liquid rubber. Specifically, the amount of initiator can be calculated using the following formula (taking n-butyllithium as an example):

[0105] Molar amount of n-butyllithium (mol) = Total mass of gel m (g) / Molecular weight M (g / mol)

[0106] The total mass of the adhesive refers to the expected preparation mass of the target high-content vinyl liquid polybutadiene, and the molecular weight refers to the molecular weight of the target high-content vinyl liquid polybutadiene.

[0107] Using the above method to determine the amount of initiator can achieve the technical effect of controlling the molecular weight of polybutadiene liquid rubber.

[0108] A fourth aspect of the present invention provides a polybutadiene liquid rubber comprising the multipolar binary structure modifier provided in the first aspect of the present invention.

[0109] The polybutadiene liquid rubber provided by this invention has the characteristics of high vinyl content and low gel content. In a preferred embodiment, the number average molecular weight of the liquid rubber is 3700-4900, and the vinyl content is greater than or equal to 88.6%, while the gel content is less than or equal to 2.4%. Specifically, the vinyl content refers to the content of polymer vinyl structure (1,2-structure) in the polybutadiene liquid rubber.

[0110] The polybutadiene liquid rubber provided by this invention is characterized by a vinyl content of ≥88.6%. When used in circuit board adhesives, this polybutadiene liquid rubber facilitates curing reactions with other resins and glass fibers to form cross-linked structures, thereby improving the overall strength and adhesion of the circuit board. Furthermore, the polybutadiene liquid rubber provided by this invention also has a gel content of ≤2.4%. Here, gel refers to a three-dimensional network of macromolecules formed by the reaction of numerous double bonds, and gel content refers to the amount of insoluble matter remaining on a 125-micron (120-mesh) filter after the polybutadiene liquid rubber has been dissolved in toluene for a period of time. The lower gel content of the polybutadiene liquid rubber, when used in circuit board adhesives, can further increase the overall bonding strength of the circuit board, resulting in higher quality and longer service life.

[0111] This invention does not limit the preparation method of the polybutadiene liquid rubber; methods commonly used in the art can be used. For example, in one embodiment, the 1,3-butadiene monomer can be polymerized using the multi-component binary structure modifier provided in the first aspect of this invention under the action of an initiator, and the polymerization temperature is controlled to be less than or equal to 0 degrees Celsius to obtain the above-mentioned polybutadiene liquid rubber.

[0112] The following will provide a detailed description of the multipolar binary structure modifier, its preparation method, and its application provided by the present invention, with reference to specific embodiments.

[0113] Raw material source:

[0114] 1,3-Butadiene, 99% purity, Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0115] 3,5-Diamino-4-methylbenzenesulfonic acid, 97% purity, Wuhan Jiyesheng Chemical Co., Ltd.

[0116] Tetrahydro-2-furanopropanol, 98% purity, Shanghai Jizhi Biochemical Technology Co., Ltd.

[0117] n-Butyllithium, 98% purity, Nanjing Tonglian Chemical Co., Ltd.

[0118] All other reagents are commercially available industrial products.

[0119] The conversion rate is calculated as follows:

[0120] There is a positive correlation between the conversion rate and molecular weight of anionic polymerization; that is, as the conversion rate increases, the molecular weight of the polymer also increases.

[0121] Single-unit conversion rate = (Number of converted units / Total number of units) × 100%

[0122] The conversion quantity refers to the molecular weight of the gel sample taken within a specific time period, while the total quantity refers to the total molecular weight of the polymer reached by the monomers participating in the reaction.

[0123] Example 1

[0124] (I) Preparation of multipolar binary structure regulator: 150g of 3,5-diamino-4-methylbenzenesulfonic acid, 315g of chlorosulfonic acid and 6.0g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 43℃ and stirred at 100rpm for 1.6hr. Then 350g of tetrahydro-2-furanpropanol was added and the mixture was heated to 112℃. 70g of sodium hydroxide solution (molar concentration of 15.5mol / L) was added to catalyze the reaction for 2.6hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.5mol / L). The mixture was washed, separated, dried and distilled to obtain the multipolar binary structure regulator (yield 90.1%).

[0125] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged three times. Then, 4000g of cyclohexane, 230g of 1,3-butadiene, and 200mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 600rpm and cooled to -5℃. Then, 69mmol of n-butyllithium was added to react. When the conversion rate reached 14%, 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier, and 47mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 65%, 120g of cyclohexane was added to further react. The reaction was continued with 1,3-butadiene, 81 mmol of multipolar binary structure modifier, and 28 mmol of n-butyllithium. When the conversion rate reached 95%, 15 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 6 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 30 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0126] Example 2

[0127] (I) Preparation of multipolar binary structure regulator: 160g of 3,5-diamino-4-methylbenzenesulfonic acid, 352g of chlorosulfonic acid and 7.1g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 45℃ and stirred at 120rpm for 1.8hr. Then 340g of tetrahydro-2-furanpropanol was added and the mixture was heated to 115℃. 75g of sodium hydroxide solution (molar concentration of 15.9mol / L) was added to catalyze the reaction for 2.8hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.5mol / L). The mixture was washed, separated, dried and distilled to obtain the multipolar binary structure regulator (yield 90.7%).

[0128] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged three times. Then, 4200g of cyclohexane, 240g of 1,3-butadiene, and 195mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 620rpm and cooled to -6℃. Then, 65mmol of n-butyllithium was added to react. When the conversion rate reached 14%, 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier, and 45mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 66%, 110g of cyclohexane was added to react. The reaction was continued with 1,3-butadiene, 80 mmol of multipolar binary structure modifier, and 26 mmol of n-butyllithium. When the conversion rate reached 95%, 17 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 7 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 32 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0129] Example 3

[0130] (I) Preparation of multipolar binary structure regulator: 170g of 3,5-diamino-4-methylbenzenesulfonic acid, 391g of chlorosulfonic acid and 8.5g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 47℃ and stirred at 150rpm for 1.9hr. Then 330g of tetrahydro-2-furanpropanol was added and the mixture was heated to 120℃. 80g of sodium hydroxide solution (molar concentration of 16.3mol / L) was added to catalyze the reaction for 3.0hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.5mol / L). The mixture was washed, separated, dried and distilled to obtain the multipolar binary structure regulator (yield 91.6%).

[0131] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged three times. Then, 4500g of cyclohexane, 250g of 1,3-butadiene, and 200mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 640rpm and cooled to -7℃. Then, 63mmol of n-butyllithium was added to react. When the conversion rate reached 15%, 150g of 1,3-butadiene, 138mmol of multipolar binary structure modifier, and 42mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 67%, 100g of cyclohexane was added to react. The reaction was continued with 1,3-butadiene, 83 mmol of multipolar binary structure modifier, and 25 mmol of n-butyllithium. When the conversion rate reached 95.4%, 20 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 9 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 35 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was then separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0132] Example 4

[0133] (I) Preparation of multipolar binary structure regulator: 180g of 3,5-diamino-4-methylbenzenesulfonic acid, 430g of chlorosulfonic acid and 9.2g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 49℃ and stirred at 170rpm for 2.0hr. Then 320g of tetrahydro-2-furanpropanol was added and the mixture was heated to 124℃. 84g of sodium hydroxide solution (molar concentration of 16.8mol / L) was added to catalyze the reaction for 3.1hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.6mol / L). The mixture was washed, separated, dried and distilled to obtain the multipolar binary structure regulator (yield 92.4%).

[0134] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged four times. Then, 4600g of cyclohexane, 260g of 1,3-butadiene, and 195mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 660rpm and cooled to -8℃. Then, 60mmol of n-butyllithium was added to react. When the conversion rate reached 15.7%, 160g of 1,3-butadiene, 135mmol of multipolar binary structure modifier, and 40mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 68%, 80g of cyclohexane was added to further react. The reaction was continued with 1,3-butadiene, 75 mmol of multipolar binary structure modifier, and 22 mmol of n-butyllithium. When the conversion rate reached 95.6%, 21 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 8 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 35 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0135] Example 5

[0136] (I) Preparation of multipolar binary structure regulator: 190g of 3,5-diamino-4-methylbenzenesulfonic acid, 470g of chlorosulfonic acid and 11.3g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 50℃ and stirred at 190rpm for 2.2hr. Then 310g of tetrahydro-2-furanpropanol was added and the mixture was heated to 127℃. 87g of sodium hydroxide solution (molar concentration of 17.2mol / L) was added to catalyze the reaction for 3.3hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.7mol / L). The multipolar binary structure regulator was obtained by washing, separation, drying and distillation (yield 93.0%).

[0137] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged four times. Then, 4800g of cyclohexane, 270g of 1,3-butadiene, and 203mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 680rpm and cooled to -9℃. Then, 58mmol of n-butyllithium was added to react. When the conversion rate reached 16.5%, 170g of 1,3-butadiene, 130mmol of multipolar binary structure modifier, and 38mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 69%, 60g of cyclohexane was added to further react. The reaction was continued with 1,3-butadiene, 70 mmol of multipolar binary structure modifier, and 20 mmol of n-butyllithium. When the conversion rate reached 95.8%, 23 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 9 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 35 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0138] Example 6

[0139] (I) Preparation of multipolar binary structure regulator: 200g of 3,5-diamino-4-methylbenzenesulfonic acid, 520g of chlorosulfonic acid and 14.0g of sodium chloride were added to a 2000mL three-necked flask. The mixture was heated to 52℃ and stirred at 200rpm for 2.3hr. Then 300g of tetrahydro-2-furanpropanol was added and the mixture was heated to 130℃. 90g of sodium hydroxide solution (molar concentration of 17.6mol / L) was added to catalyze the reaction for 3.5hr. After the reaction was completed, the mixture was cooled to room temperature and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration of 0.8mol / L). The mixture was washed, separated, dried and distilled to obtain the multipolar binary structure regulator (yield 93.5%).

[0140] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: In a jacketed 10L stainless steel polymerization reactor, argon gas was purged five times. Then, 5000g of cyclohexane, 280g of 1,3-butadiene, and 204mmol of multipolar binary structure modifier were added sequentially to the polymerization reactor. The mixture was stirred at 700rpm and cooled to -10℃. Then, 55mmol of n-butyllithium was added to react. When the conversion rate reached 17.0%, 180g of 1,3-butadiene, 130mmol of multipolar binary structure modifier, and 35mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 70%, 40g of cyclohexane was added to further react. The reaction was continued with 1,3-butadiene, 60 mmol of multipolar binary structure modifier, and 16 mmol of n-butyllithium. When the conversion rate reached 96.0%, 25 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 10 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 40 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0141] Example 7

[0142] This embodiment is basically the same as Embodiment 1, except that the same molar amount of 3,5-diamino-4-propylbenzenesulfonic acid is used instead of 3,5-diamino-4-methylbenzenesulfonic acid.

[0143] Example 8

[0144] This embodiment is basically the same as Example 1, except that the same molar amount of 3,5-diamino-4-hexylbenzenesulfonic acid is used instead of 3,5-diamino-4-methylbenzenesulfonic acid.

[0145] Example 9

[0146] This embodiment is basically the same as Example 1, except that the same molar amount of 3,5-diamino-4-dodecylbenzenesulfonic acid is used instead of 3,5-diamino-4-methylbenzenesulfonic acid.

[0147] Example 10

[0148] This embodiment is basically the same as Example 1, except that the same molar amount of tetrahydro-2-furanmethanol is used instead of tetrahydro-2-furanpropanol.

[0149] Example 11

[0150] This embodiment is basically the same as Example 1, except that the same molar amount of tetrahydro-2-furanbutanol is used instead of tetrahydro-2-furanpropanol.

[0151] Comparative Example 1

[0152] (I) Preparation of multipolar binary structure regulator: Other conditions are the same as in Example 1, except that 3,5-diamino-4-methylbenzenesulfonic acid is not added in the preparation of the multipolar binary structure regulator, but 2-methyl-5-aminobenzenesulfonic acid is added, and the amount added is 150g, that is, 150g is added to a 2000mL three-necked flask. 2-Methyl-5-aminobenzenesulfonic acid, 315 g chlorosulfonic acid, and 6.0 g sodium chloride were heated to 43°C, and the mixture was stirred at 100 rpm for 1.6 hours. Then, 350 g tetrahydro-2-furanpropanol was added, and the mixture was heated to 112°C. 70 g sodium hydroxide solution (molar concentration 15.5 mol / L) was added to catalyze the reaction for 2.6 hours. After the reaction was completed, the material was cooled to room temperature, and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration 0.5 mol / L). After washing, separation, drying, and distillation, a multipolar binary structure regulator a was obtained (yield 90.3%).

[0153] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions were the same as in Example 1, except that a multipolar binary structure modifier a was added during the preparation of the low-gel, high-vinyl polybutadiene liquid rubber. Specifically, in a 10L stainless steel polymerization reactor with a jacket, argon gas was introduced three times for purging. Then, 4000g of cyclohexane, 230g of 1,3-butadiene, and 200mmol of multipolar binary structure modifier a were added sequentially to the polymerization reactor. The mixture was stirred at 600rpm and cooled to -5℃. Then, 69mmol of n-butyllithium was added to react. When the conversion rate reached 14%, 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier a, and 47mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 65%, 120g of cyclohexane was added to react. The reaction was continued with 1,3-butadiene, 81 mmol of multipolar binary structure modifier a, and 28 mmol of n-butyllithium. When the conversion rate reached 95%, 15 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 6 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 30 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0154] Comparative Example 2

[0155] (I) Preparation of multipolar binary structure modifier: Other conditions are the same as in Example 2, except that tetrahydro-2-furanpropanol is not added during the preparation of the multipolar binary structure modifier. Instead, 1-butoxy-2-propanol is added in an amount of 340g, that is, 160g is added to a 2000mL three-necked flask. 3,5-Diamino-4-methylbenzenesulfonic acid, 352 g of chlorosulfonic acid, and 7.1 g of sodium chloride were heated to 45°C, and the mixture was stirred at 120 rpm for 1.8 hours. Then, 340 g of 1-butoxy-2-propanol was added, and the mixture was heated to 115°C. 75 g of sodium hydroxide solution (molar concentration 15.9 mol / L) was added to catalyze the reaction for 2.8 hours. After the reaction was completed, the material was cooled to room temperature, and the pH of the solution was adjusted to neutral with dilute hydrochloric acid solution (molar concentration 0.5 mol / L). After washing, separation, drying, and distillation, a multipolar binary structure regulator b was obtained (yield 88.3%).

[0156] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions were the same as in Example 2, except that a multipolar binary structure modifier b was added during the preparation of the low-gel, high-vinyl polybutadiene liquid rubber. Specifically, in a 10L stainless steel polymerization reactor with a jacket, argon gas was introduced three times for purging. Then, 4200g of cyclohexane, 240g of 1,3-butadiene, and 195mmol of multipolar binary structure modifier b were added sequentially to the polymerization reactor. The stirring speed was 620rpm. When the temperature was lowered to -6℃, 65mmol of n-butyllithium was added for reaction. When the conversion rate reached 14%, 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier b, and 45mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 66%, 110g of cyclohexane was added. The reaction was continued with 1,3-butadiene, 80 mmol of multipolar binary structure modifier b, and 26 mmol of n-butyllithium. When the conversion rate reached 95%, 17 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 7 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 32 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0157] Comparative Example 3

[0158] Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions were the same as in Example 3, except that a multipolar binary structure modifier was not added during the preparation of the low-gel, high-vinyl polybutadiene liquid rubber. Instead, tetrahydro-2-furanpropanol was added. Specifically, in a 10L stainless steel polymerization reactor with a jacket, argon gas was purged three times. Then, 4500g of cyclohexane, 250g of 1,3-butadiene, and 200mmol of tetrahydro-2-furanpropanol were added sequentially to the polymerization reactor. The mixture was stirred at 640rpm and cooled to -7°C. Then, 63mmol of n-butyllithium was added to react. When the conversion rate reached 15%, 150g of 1,3-butadiene, 138mmol of tetrahydro-2-furanpropanol, and 42mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 67%, 100g of tetrahydro-2-furanpropanol was added to further react. The reaction was continued with 1,3-butadiene, 83 mmol tetrahydro-2-furanpropanol, and 25 mmol n-butyllithium. When the conversion rate reached 95.4%, 20 g ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 9 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 35 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was then separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0159] Comparative Example 4

[0160] Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions were the same as in Example 4, except that a multipolar binary structure modifier was not added during the preparation of the low-gel, high-vinyl polybutadiene liquid rubber. Instead, 3,5-diamino-4-methylbenzenesulfonic acid was added. Specifically, in a 10L stainless steel polymerization reactor with a jacket, argon gas was purged three times. Then, 4500g of cyclohexane, 270g of 1,3-butadiene, and 300mmol of 3,5-diamino-4-methylbenzenesulfonic acid were added sequentially to the polymerization reactor. The mixture was stirred at 640rpm and cooled to 3°C. Then, 65mmol of n-butyllithium was added to react. When the conversion rate reached 17%, 146g of 1,3-butadiene, 185mmol of 3,5-diamino-4-methylbenzenesulfonic acid, and 40mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 71%, 84g of cyclohexane was added to react. The reaction was continued with 1,3-butadiene, 110 mmol of 3,5-diamino-4-methylbenzenesulfonic acid, and 24 mmol of n-butyllithium. When the conversion rate reached 94%, 20 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 8 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 34 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0161] Comparative Example 5

[0162] (a) Preparation of multipolar binary structure modifier: Same as in Example 5.

[0163] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions were the same as in Example 5, except that no multipolar binary structure modifier was added when the conversion rate reached 16.5% during the preparation of the low-gel, high-vinyl polybutadiene liquid rubber. Specifically, in a 10L stainless steel polymerization reactor with a jacket, argon gas was purged four times, and then 4800g of cyclohexane, 270g of 1,3-butadiene, and 203mmol of multipolar binary structure modifier were added sequentially. The mixture was stirred at 680rpm and cooled to -9℃. Then, 58mmol of n-butyllithium was added to react. When the conversion rate reached 16.5%, 170g of 1,3-butadiene and 38mmol of n-butyllithium were added to continue the reaction. When the conversion rate reached 69%, 60g of cyclohexane was added to react. The reaction of 1,3-butadiene and 20 mmol of n-butyllithium continued until the conversion rate reached 95.8%. 23 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 9 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 35 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was then separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0164] Comparative Example 6

[0165] (a) Preparation of multipolar binary structure modifier: Same as in Example 6.

[0166] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions are the same as in Example 6, except that in the preparation of low-gel, high-vinyl polybutadiene liquid rubber, 1,3-butadiene, multipolar binary structure modifier, and n-butyllithium raw material are added to the polymerization reactor all at once, instead of being added in three steps. That is, in a 10L stainless steel polymerization reactor with a jacket, argon gas is introduced to purge five times, and then 5000g of cyclohexane, 500g of... 1,3-Butadiene and 394 mmol of a multipolar binary structure modifier were stirred at 700 rpm and cooled to -10 °C. Then, 106 mmol of n-butyllithium was added to react. When the conversion rate reached 96.0%, 25 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 10 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 40 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0167] Comparative Example 7

[0168] (a) Preparation of multipolar binary structure modifier: Same as in Example 6.

[0169] (II) Preparation of low-gel, high-vinyl polybutadiene liquid rubber: Other conditions are the same as in Example 6, except that the reaction temperature in the preparation of low-gel, high-vinyl polybutadiene liquid rubber is not -10℃, but -1℃. That is, in a 10L stainless steel polymerization reactor with a jacket, argon gas is introduced to purge five times, and then 5000g of cyclohexane, 280g of 1,3-butadiene and 204mmol of multipolar binary structure modifier are added to the polymerization reactor in sequence. The stirring speed is 700rpm. When the temperature is lowered to -1℃, 55mmol of n-butyllithium is added to react. When the conversion rate reaches 17.0%, 180g of 1,3-butadiene, 130mmol of multipolar binary structure modifier and 35mmol of n-butyllithium are added to continue the reaction. When the conversion rate reaches 70%, 40g of cyclohexane is added to further react. The reaction was continued with 1,3-butadiene, 60 mmol of multipolar binary structure modifier, and 16 mmol of n-butyllithium. When the conversion rate reached 96.0%, 25 g of ethanol was added to terminate the polymerization reaction, resulting in a polymerization mixture. Subsequently, coagulation was carried out by adding 3 L of deionized water and 10 mL of sulfuric acid (molar concentration of 0.4 mol / L) to the mixture. After stirring for 40 minutes, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed three times with 5 L of water. The resulting oil phase was then subjected to vacuum distillation and vacuum drying at 75 °C to obtain a low-gel, high-vinyl polybutadiene liquid rubber.

[0170] Comparative Example 8

[0171] This embodiment is basically the same as Example 1, except that in step (ii), the timing of adding 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier, and 47mmol of n-butyllithium is adjusted from 14% to 30% of the conversion rate.

[0172] Comparative Example 9

[0173] This embodiment is basically the same as Example 1, except that in step (ii), the timing of adding 120g of 1,3-butadiene, 81mmol of multipolar binary structure modifier, and 28mmol of n-butyllithium is adjusted from 65% to 80% of the conversion rate.

[0174] Comparative Example 10

[0175] This embodiment is basically the same as Example 1, except that in step (ii), the timing of adding 150g of 1,3-butadiene, 136mmol of multipolar binary structure modifier, and 47mmol of n-butyllithium is adjusted from 14% to 30% of the conversion rate; at the same time, the timing of adding 120g of 1,3-butadiene, 81mmol of multipolar binary structure modifier, and 28mmol of n-butyllithium is adjusted from 65% to 80% of the conversion rate.

[0176] Test case

[0177] 1. The multipolar binary structure modifier prepared in Example 1 was subjected to infrared spectroscopy testing, and the results are shown in Figure 1.

[0178] As shown in Figure 1, the wavenumber is between 860 and 850 cm⁻¹. -1 Characteristic peaks of epoxy groups appear at [location]; at wavenumbers of 1150–1250 cm⁻¹ -1 Characteristic peaks of sulfonic acid groups appeared; at wavenumbers of 1730–1720 cm⁻¹. -1 Characteristic peaks of ester groups appeared; at wavenumbers of 3100–3200 cm⁻¹ -1 The characteristic peaks of phenyl appeared; at wavenumbers of 3400–3300 cm⁻¹. -1 A sharp absorption peak appeared for the amine group.

[0179] This indicates that the multipolar binary structure modifier prepared in Example 1 has the structure shown in Formula 1.

[0180] 2. The molecular weight of the polybutadiene liquid rubber prepared in each example and comparative example was determined. 1 HNBR vinyl content determination, aging performance test and gel content test.

[0181] in:

[0182] Molecular weight determination: Molecular weight was determined using a Waters 2414 gel permeation chromatography (GPC) system (Waters, Inc., USA). A polystyrene standard was used as the calibration curve. The mobile phase was tetrahydrofuran, the column temperature was 40℃, the sample concentration was 1 mg / ml, the injection volume was 50 μL, the elution time was 40 min, and the flow rate was 1 ml·min⁻¹.

[0183] 1 Determination of HNBR vinyl groups: using proton nuclear magnetic resonance spectroscopy (NMR) 1 The vinyl content of low-gel, high-vinyl polybutadiene liquid rubber was analyzed and characterized by 1H NMR. The main methods are as follows: 1. The product was completely dissolved in deuterated chloroform to prepare a 1H NMR sample; 2. The 1H NMR spectrum was measured and analyzed.

[0184] Aging performance test: The method in standard GB / T 3512 2014 shall be followed.

[0185] Gel content test: Perform the method in standard SH / T 1050-91.

[0186] The test results are shown in Table 1.

[0187] Table 1 Properties of low-gel, high-vinyl-butadiene liquid rubber

[0188] As shown in Table 1, compared with Comparative Examples 1-7, the polybutadiene liquid rubber prepared using a multipolar binary structure modifier has a higher vinyl (1,2-structure) content and a lower gel content than the polybutadiene liquid rubber prepared using a mono-structure modifier.

[0189] Example 6 uses a three-step addition method, while Comparative Example 6 uses a one-step addition method. Comparing the two, the gel content of the product obtained in Example 6 is 2.9% lower than that of the product obtained in Comparative Example 6. Comparing Example 6 and Comparative Example 7, in the preparation of low-gel, high-vinyl polybutadiene liquid rubber, the gel content of the product obtained at a reaction temperature of -10℃ is 1.2% lower than that of the product obtained at a reaction temperature of -1℃. This indicates that the present invention can effectively reduce the gel content of polybutadiene liquid rubber and ensure product quality by reducing the temperature and using distributed addition to achieve distributed polymerization.

[0190] The low-gel, high-vinyl polybutadiene liquid rubber prepared by this invention showed a small decrease in vinyl (1,2-structure) content after hot air aging, only about 2%, further indicating that the 1,2-structure in the low-gel, high-vinyl polybutadiene liquid rubber prepared by this invention has good stability.

[0191] Comparing Example 1 with Comparative Examples 8-10, it can be seen that Comparative Example 8 modified the timing of adding the first component based on Example 1, Comparative Example 9 modified the timing of adding the second component based on Example 1, and Comparative Example 10 modified the timing of adding both the first and second components based on Example 1. Therefore, the gel content in the polybutadiene liquid rubber obtained in Comparative Examples 8-10 is higher than that in Example 1. This indicates that adding the first component at a conversion rate of 14%–17% and adding the second component at a conversion rate of 65%–70% can control the rapid growth and branching of polybutadiene molecular chains through segmented polymerization, reducing the aggregation of polybutadiene molecular chains and lowering the conversion to gel. The resulting polybutadiene liquid rubber has the advantage of a lower gel content.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multipolar binary structure modifier, characterized in that, The multipolar binary structure modifier has the structure shown in Formula 1: Wherein, R1 is a C1-C4 straight-chain alkyl group, and R2 is a C1-C4 straight-chain alkyl group. 12 Alkyl groups.

2. A method for preparing the multipolar binary structure modifier according to claim 1, characterized in that, The multipolar binary structure modifier is prepared by esterification of 3,5-diamino-4-alkylbenzenesulfonic acid and tetrahydro-2-furanol. The tetrahydro-2-furanol has the structure shown in Formula 2: The 3,5-diamino-4-alkylbenzenesulfonic acid has the structure shown in Formula 3:

3. The preparation method according to claim 2, characterized in that, R1 is a C1–C4 straight-chain alkyl group, and R2 is a C1–C4 straight-chain alkyl group. 12 The alkyl group; preferably R1 is n-propyl or isopropyl, and preferably R2 is methyl.

4. The preparation method according to claim 2 or 3, characterized in that, The esterification reaction specifically includes the following steps: 3,5-Diamino-4-alkylbenzenesulfonic acid, chlorosulfonic acid and sodium chloride were mixed and subjected to a first heating and stirring reaction to obtain a first heating and stirring reaction system. Tetrahydro-2-furanol and sodium hydroxide aqueous solution were added to the first heating and stirring reaction system to carry out a second heating and stirring reaction, thereby obtaining a second heating and stirring reaction system. The pH of the second heating and stirring reaction system was adjusted to 6.5–7.5, and separation was performed to obtain the multipolar binary structure regulator. The stirring speed of the first heating and stirring reaction is 100-200 rpm, the reaction temperature is 43-52℃, and the reaction time is 1.6-2.4 h; The stirring speed of the second heating and stirring reaction is 100-200 rpm, the reaction temperature is 112-130℃, and the reaction time is 2.6-3.5 h.

5. The preparation method according to any one of claims 2-4, characterized in that, In the esterification reaction, when the sum of the masses of 3,5-diamino-4-methylbenzenesulfonic acid and tetrahydro-2-furanpropanol is 100, the mass ratio of the two is (30-40):(60-70); and / or, In the esterification reaction, the mass ratio of 3,5-diamino-4-methylbenzenesulfonic acid, chlorosulfonic acid, and sodium chloride is 1:(1.5-4.0):(0.01-0.1).

6. A method for preparing polybutadiene liquid rubber, characterized in that, The 1,3-butadiene is polymerized using the multipolar binary structure modifier and initiator described in claim 1 to obtain the polybutadiene liquid rubber. The initiator is a hydrocarbon-based monolithium compound; The polymerization reaction specifically includes the following steps: Solvent, a portion of 1,3-butadiene, and a portion of the multipolar binary structure modifier are added sequentially to the reaction vessel, followed by the addition of a portion of the initiator to initiate the polymerization reaction; during the reaction, the remaining 1,3-butadiene, multipolar binary structure modifier, and initiator are added at least twice. The portion of 1,3-butadiene does not exceed 50% of the total mass of 1,3-butadiene; The polymerization reaction temperature is -10 to -5℃.

7. The preparation method according to claim 6, characterized in that, The remaining 1,3-butadiene, multipolar binary structure modifier, and initiator will be added in at least two separate additions, specifically including: When the conversion rate is 14%–17%, add the first component. When the conversion rate is 65%–70%, add the second component; When the conversion rate is 95% to 96%, a terminator is added to the reaction system to obtain the polybutadiene liquid rubber. Both the first component and the second component include 1,3-butadiene, the multipolar binary structure modifier, and the initiator.

8. The preparation method according to claim 7, characterized in that, In the first and second components, the molar ratio of the multipolar binary structure modifier to the initiator is (1.0–7.2):1; and / or, The molar ratio of a portion of the multipolar binary structure modifier and a portion of the initiator added to the container for the first time is (1.0 to 7.2):

1.

9. The preparation method according to any one of claims 6-8, characterized in that, The amount of the initiator is equal to the ratio of the expected prepared mass of the target polybutadiene liquid rubber to the molecular weight of the target polybutadiene liquid rubber.

10. A polybutadiene liquid rubber, characterized in that, It is prepared using the method for preparing polybutadiene liquid rubber according to any one of claims 6-9.

11. The polybutadiene liquid rubber according to claim 10, characterized in that, The liquid rubber has a number-average molecular weight of 3700–4900 and a vinyl content of ≥88.6%; and / or, The gel content of the liquid rubber is less than or equal to 2.4%.

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