Rare earth cis-1,4-polybutadiene rubber, its preparation method and application

Abstract

The present invention provides a novel rare earth cis-1,4-polybutadiene rubber, a preparation method thereof and an application. Among them, the preparation method of the novel rare earth cis-1,4-polybutadiene rubber comprises the following steps: Step S1, taking butadiene, an organic solvent and a rare earth catalyst for a polymerization reaction to obtain a rubber polymer; Step S2, taking a branching agent to carry out a branching reaction on the rubber polymer, and then adding a terminator to obtain the novel rare earth cis-1,4-polybutadiene rubber; wherein, the branching agent comprises a carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride. This rare earth cis-1,4-polybutadiene rubber has the advantages of a relatively narrow molecular weight distribution width, a long-chain branching structure, and relatively low cold flow resistance and gel content.

Description

Technical Field

[0001] This application relates to the technical field of rubber synthesis, and particularly relates to a rare earth cis-1,4-polybutadiene rubber, a preparation method thereof, and an application thereof. Background Art

[0002] During the polymerization of butadiene, affected by factors such as catalysts and polymerization conditions, in addition to forming linear macromolecular chains, branched chains with different structural forms will also be formed. The branched structure of the polymer molecular chain has a great influence on the properties of the polymer, and its branched structure is mainly closely related to the fluidity and viscoelasticity of the polymer. In addition, different types of branched chains have different effects on the physical and mechanical properties. For example, polymers with a linear and relatively narrow molecular weight distribution are beneficial to the injection molding process but are not conducive to the mixing process. However, a higher degree of branching has an adverse effect on the physical properties of the polymer. Therefore, an appropriate degree of branching is the key to preparing branched cis-1,4-polybutadiene rubber. Existing research shows that cis-1,4-polybutadiene rubber synthesized using rare earth catalysts basically has no branched chains and has the characteristic of easy cold flow. However, narrow distribution rare earth cis-1,4-polybutadiene rubber still requires appropriate long-chain branching to improve processing performance and cold flow properties. Research on the development of the production process of rare earth cis-1,4-polybutadiene rubber shows that when using a neodymium carboxylate catalyst system, polymers with high cold flow or low cold flow, and the Mooney viscosity and molecular weight distribution can be adjusted arbitrarily can be prepared according to different compositions of the catalyst system and process conditions. However, when the molecular weight distribution of neodymium-based cis-1,4-polybutadiene rubber is narrow, it generally has high cold flow. In order to reduce the cold flow of rare earth cis-1,4-polybutadiene rubber, researchers in the industry have carried out relevant research on adding modifiers to rare earth cis-1,4-polybutadiene rubber.

[0003] In the prior art, the invention patent publication number: EP0386808A1 (1990) shows that Enichem used phosphorus trichloride as a modifier. When the conversion rate of the polymerization reaction reached more than 95%, the Mooney viscosity was measured to be 28 Pa·s by sampling; then 0.1% of the modifier phosphorus trichloride was added to the polymer, and after reacting for another 15 minutes at 110 °C, an antioxidant and a terminator were added, and the solvent was removed and dried, and the Mooney viscosity was measured to be 40 Pa·s. The data shows that phosphorus trichloride is an effective modifier, which not only reduces the cold flow property, but also shortens the combination time of the rubber compound with carbon black, and also has the effect of increasing the Mooney viscosity. In the invention patent publication (announcement) number: US3374191A (1968), Bayer had already discovered in the 1960s that sulfur chlorides without oxygen could effectively improve the cold flow property of diene rubbers, without damaging their processing properties, and had no adverse effects on the physical and mechanical properties of vulcanized rubbers. In the invention patent publication (announcement) number: US5567784A (1996), Bayer used this bifunctional sulfur derivative as a branching additive to improve the cold flow property of rare earth cis-1,4-polybutadiene rubber and prepare branched rare earth cis-1,4-polybutadiene rubber. In its examples, a neodymium neodecanoate ternary system and butadiene were polymerized in an adiabatic polymerization manner, the polymerization temperature reached 110 °C, the pressure was about 5 to 7 bar, the conversion rate was greater than 99%, and stearic acid and an antioxidant were added to terminate the polymerization; then the pressure was reduced to 1.5 bar, low-boiling components and part of the solvent volatilized, and the concentration of the rubber solution increased from 17% to 18%. An S2Cl2 solution was added under stirring, and the reaction was stirred at 110 °C for 30 minutes, and then treated and dried in the usual method. The measured Mooney viscosity was 44 Pa·s, and the cold flow value was 10 mg / min. In the invention patent publication (announcement) number: US8586678B2 (2013), Sullivan et al. described the addition of sulfide to increase the reaction as follows: the addition reaction of sulfur atoms with the double bonds of two macromolecular chains becomes a long-chain branched macromolecule, the molecular weight increases, and the Mooney viscosity increases. However, sulfur dichloride, as a low-temperature vulcanizing agent for rubber, has high chemical reactivity and can undergo chemical reactions with many inorganic and organic compounds, and is easy to react with hydrocarbons, alcohols, aldehydes, ethers, carboxylic acids, esters, amines, alkenes, etc. It can react violently with unsaturated double bonds, and sulfur and chlorine are respectively connected to the unsaturated bonds. Therefore, when using sulfur dichloride to prepare branched rare earth cis-1,4-polybutadiene rubber, it has a particularly strong tendency to gel, especially during the dispersion process of high-viscosity cis-1,4-polybutadiene rubber solution, it is extremely easy to form local gel clusters. And in the invention patent publication (announcement) number: US3374191A, the addition amount of sulfur dichloride used is 0.5% of polybutadiene, while in the invention patent publication (announcement) number: US5567784A, it is necessary to add 0.05 to 0.5% of polybutadiene. As the dosage is on the high side, it is easy to aggravate the gelation. In addition, sulfur dichloride is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution.

[0004] Based on this, in the face of the technical problems existing in the preparation of rare earth cis-1,4-polybutadiene rubber in the prior art, such as serious gelation, or cold flow property, or wide molecular weight distribution, or the dichloride disulfide branching agent is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution, it is urgent to provide a rare earth cis-1,4-polybutadiene rubber and its preparation method to improve the above problems. Summary of the Invention

[0005] The main object of the present invention is to provide a rare earth cis-1,4-polybutadiene rubber, its preparation method and application, so as to solve the technical problems existing in the preparation of rare earth cis-1,4-polybutadiene rubber in the prior art, such as serious gelation, or cold flow property, or wide molecular weight distribution, or the dichloride disulfide branching agent is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution.

[0006] In order to achieve the above object, according to one aspect of the present invention, a preparation method of rare earth cis-1,4-polybutadiene rubber is provided. The preparation method includes the following steps: Step S1, taking butadiene, an organic solvent, and a rare earth catalyst for a polymerization reaction to obtain a rubber polymer; Step S2, taking a branching agent for a branching reaction in the rubber polymer, and then adding a terminator to obtain rare earth cis-1,4-polybutadiene rubber; wherein, the branching agent includes a carbon tetrachloride solution of dichloride disulfide and an aluminum trichloride complex.

[0007] Further, in Step S2, in the branching agent, the molar ratio of dichloride disulfide to aluminum trichloride is (0.2~1.5):1; by weight percentage, preferably the weight of carbon tetrachloride accounts for 40~98wt% of the branching agent.

[0008] Further, in Step S2, the temperature of the branching reaction is 20~100°C, and the reaction time is 10~120 min.

[0009] Further, in Step S1, the organic solvent is hexane; preferably, the polymerization reaction is carried out in a nitrogen atmosphere.

[0010] Further, in Step S1, the rare earth catalyst includes a rare earth compound and an alkyl aluminum. The molar ratio of the rare earth compound to the alkyl aluminum is (0.02~0.25):1. The rare earth compound is selected from one or more of neodymium neodecanoate, neodymium isooctanoate, or neodymium phosphate ester; the alkyl aluminum is a mixture of diisobutylaluminum hydride and diisobutylaluminum chloride, and the molar ratio of diisobutylaluminum hydride to diisobutylaluminum chloride is (4~15):1.

[0011] Further, in Step S1, by weight percentage, the weight ratio of butadiene to the organic solvent is (0.12~0.30):1.

[0012] Further, in Step S1, the reaction temperature of the polymerization reaction is 20~90°C, and the reaction time is 1~10 h.

[0013] To achieve the above object, according to one aspect of the present invention, there is provided a rare earth cis-1,4-polybutadiene rubber, which is obtained by the preparation method of the above rare earth cis-1,4-polybutadiene rubber.

[0014] Furthermore, the content of cis-1,4 structure polybutadiene rubber in the rare earth cis-1,4-polybutadiene rubber is 95-98%, the Mooney viscosity of the rare earth cis-1,4-polybutadiene rubber is 35-80, and the polydispersity index PDI of its molecular weight distribution is 2-3.

[0015] According to another aspect of the present invention, there is provided an application of the rare earth cis-1,4-polybutadiene rubber in the fields of tires, conveyor belts or shoe making, and the rare earth cis-1,4-polybutadiene rubber is the above rare earth cis-1,4-polybutadiene rubber.

[0016] The rare earth cis-1,4-polybutadiene rubber obtained by applying the technical solution of the present invention has the advantages of a narrow molecular weight distribution width, a long-chain branched structure and cold flow resistance, and a low gel content. It has excellent comprehensive properties and broad application prospects. Description of the Drawings

[0017] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. In the drawings:

[0018] Figure 1 Shows the infrared spectrum of the rare earth cis-1,4-polybutadiene rubber prepared according to Example 1 of the present invention;

[0019] Figure 2 Shows the gel permeation chromatography of the rare earth cis-1,4-polybutadiene rubber prepared according to Example 1 of the present invention;

[0020] Figure 3 Shows the relationship diagram between the intrinsic viscosity and molecular weight of the rare earth cis-1,4-polybutadiene rubber prepared according to Example 1 of the present invention. Detailed Embodiments

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0022] As described in the background art section of the present invention, in the prior art, rare earth cis-1,4-polybutadiene rubber has technical problems such as serious gelation, or cold flow property, or relatively wide molecular weight distribution, or the fact that the branching agent sulfur dichloride is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution. Based on this, the present invention provides a preparation method of rare earth cis-1,4-polybutadiene rubber, and the preparation method includes the following steps: Step S1, taking butadiene, an organic solvent, and a rare earth catalyst to carry out a polymerization reaction to obtain a rubber polymer; Step S2, taking a branching agent to carry out a branching reaction in the rubber polymer, and then adding a terminator to obtain rare earth cis-1,4-polybutadiene rubber; wherein, the branching agent includes a carbon tetrachloride solution of sulfur dichloride and an aluminum trichloride complex.

[0023] Due to inappropriate branching degree, or relatively wide molecular weight distribution, or inappropriate Mooney viscosity, etc. in the rare earth cis-1,4-polybutadiene rubber in the prior art, there are technical problems such as serious gelation, or cold flow property, or relatively wide molecular weight distribution, or the fact that the branching agent sulfur dichloride is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution. The present invention provides a preparation method of rare earth cis-1,4-polybutadiene rubber, and the preparation method includes the following steps: Step S1, taking butadiene, an organic solvent, and a rare earth catalyst to carry out a polymerization reaction to obtain a rubber polymer; Step S2, taking a branching agent to carry out a branching reaction in the rubber polymer, and then adding a terminator to obtain rare earth cis-1,4-polybutadiene rubber. In particular, the branching agent provided in the present invention is a carbon tetrachloride solution including sulfur dichloride and an aluminum trichloride complex. On the one hand, it can avoid the problem that sulfur dichloride with high chemical reactivity is used alone as a branching agent in the preparation steps of conventional rare earth cis-1,4-polybutadiene rubber, thereby causing gel formation and affecting the reaction process. On the other hand, it can also inhibit the reaction of sulfur dichloride with the residual butadiene in the rubber solution to produce cyclic small molecules, thereby improving the polymerization reaction conversion rate and optimizing the reaction process. Moreover, the rare earth cis-1,4-polybutadiene rubber prepared by this method has the advantages of a relatively narrow molecular weight distribution width, long-chain branching structure, cold flow resistance, and low gel content, and has excellent comprehensive performance and broad industrial application prospects.

[0024] In a preferred embodiment, in Step S2, in the branching agent, the molar ratio of sulfur dichloride to aluminum trichloride is (0.2~1.5):1; calculated by weight percentage, further preferably, the addition amount of carbon tetrachloride accounts for 40~98wt% of the branching agent; so as to further exert the characteristics of the branching agent and obtain rare earth cis-1,4-polybutadiene rubber with a relatively narrow molecular weight distribution width and long-chain branching structure.

[0025] In order to further prepare rare earth cis-1,4-polybutadiene rubber with excellent performance, having the advantages of cold flow resistance and low gel content, preferably in step S2, the temperature of the branching reaction is 20-100 °C, and the reaction time is 10-120 min; so that the branching reaction proceeds sufficiently, improving the performance of the branched product, and obtaining rare earth cis-1,4-polybutadiene rubber with a narrow molecular weight distribution width and long chain branching structure.

[0026] In a preferred embodiment, in step S1, the organic solvent is hexane, so that the reaction raw materials are fully dissolved in the solvent to obtain a homogeneous and stable reaction solution, and further making the polymerization reaction more sufficient; preferably, the polymerization reaction is carried out in a nitrogen atmosphere to avoid adverse effects of impurities in the air on the polymerization reaction product and improve the performance of the rare earth cis-1,4-polybutadiene rubber.

[0027] In order to further prepare rare earth cis-1,4-polybutadiene rubber with a narrow molecular weight distribution width, long chain branching structure, cold flow resistance and low gel content, preferably the rare earth catalyst includes a rare earth compound and an alkyl aluminum, and preferably the molar ratio of the rare earth compound to the alkyl aluminum is (0.02-0.25):1; further preferably, the rare earth compound is selected from one or more of neodymium neodecanoate, neodymium isooctanoate or neodymium phosphate ester; more preferably, the alkyl aluminum is a mixture of diisobutyl aluminum hydride and diisobutyl aluminum chloride, and the molar ratio of diisobutyl aluminum hydride to diisobutyl aluminum chloride is (4-15):1.

[0028] In a preferred embodiment, in step S1, by weight percentage, the weight ratio of butadiene to the organic solvent is (0.12-0.30):1, thus preparing for obtaining rare earth cis-1,4-polybutadiene rubber with excellent performance.

[0029] In order to prepare a rubber polymer with excellent performance and further prepare rare earth cis-1,4-polybutadiene rubber with a narrow molecular weight distribution width and long chain branching structure, preferably in step S1, the reaction temperature of the polymerization reaction is 20-90 °C, and the reaction time is 1-10 h.

[0030] On the other hand, the present invention also provides a rare earth cis-1,4-polybutadiene rubber, which is obtained by the above method for preparing rare earth cis-1,4-polybutadiene rubber. This rare earth cis-1,4-polybutadiene rubber has the advantages of a narrow molecular weight distribution width, long chain branching structure, cold flow resistance and low gel content, has excellent comprehensive performance, and has a broad application prospect.

[0031] In a preferred embodiment, the content of cis-1,4-polybutadiene rubber in the rare earth cis-1,4-polybutadiene rubber is 95-98%; preferably, the Mooney viscosity of the rare earth cis-1,4-polybutadiene rubber is 35-80, and its molecular weight distribution width coefficient PDI is 2-3.

[0032] On the other hand, the present invention also provides an application of rare earth cis-1,4-polybutadiene rubber in the fields of tires, conveyor belts or shoe-making, and the rare earth cis-1,4-polybutadiene rubber is the above-mentioned rare earth cis-1,4-polybutadiene rubber.

[0033] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0034] Example 1

[0035] Under nitrogen protection, 1700 g of hexane, 300 g of butadiene, 0.56 mmol of neodymium neodecanoate, 8.33 mmol of diisobutylaluminum hydride, and 1.67 mmol of diisobutylaluminum chloride were successively added to a 5 L reactor, and a polymerization reaction was carried out at 50 °C for 4 h. A carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride (wherein, disulfur dichloride is 0.060 g, aluminum trichloride is 0.059 g, and carbon tetrachloride is 2.4 g) was added, and a branching reaction was carried out at 50 °C for 0.5 h. After the branched product was taken out from the polymerization kettle, an ethanol solution of 2,6-di-tert-butyl-p-cresol was added to terminate the reaction, and rare earth cis-1,4-polybutadiene rubber was obtained. The conversion rate was 98.0%, the content of cis-1,4 structure in the polymer was 98.0%, the Mooney viscosity was 48, the polydispersity index PDI of the molecular weight distribution was 2.06, and the gel content was 0. Figure 1 is its infrared spectrum, indicating the successful synthesis of the cis-structured polymer. Figure 2 is its GPC spectrum, which has a narrow molecular weight distribution range. Figure 3 is a graph showing the relationship between the intrinsic viscosity and the molecular weight of the rare earth cis-1,4-polybutadiene rubber. The viscosity of the rare earth cis-1,4-polybutadiene rubber increases with the increase of the molecular weight. Specifically, the small molecular weight part of the rare earth cis-1,4-polybutadiene rubber with a molecular weight below 100,000 is a linear structure; after the molecular weight is greater than 100,000, the molecular chain shows a branched structure, and its viscosity is lower than the theoretical viscosity of the linear structure, and with the increase of the molecular weight of the polymer chain, the degree of branching increases. Thus, it can be shown that the prepared rare earth cis-1,4-polybutadiene rubber is a branched structure.

[0036] Example 2

[0037] The difference from Example 1 is only that: 5.56 mmol of diisobutylaluminum hydride and 1.39 mmol of diisobutylaluminum chloride were used. Rare earth cis-1,4-polybutadiene rubber was obtained, with a conversion rate of 98.0%, a content of cis-1,4 structure in the polymer of 98.0%, a Mooney viscosity of 65, a molecular weight distribution of 2.6, and a gel content of 0.

[0038] Example 3

[0039] The difference from Example 1 is only that: a carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride (wherein, disulfur dichloride is 0.012 g, aluminum trichloride is 0.060 g, and carbon tetrachloride is 1.44 g) is added to obtain rare-earth cis-1,4-polybutadiene rubber, with a conversion rate of 97.5%, the content of cis-1,4 structure in the polymer being 96.9%, the Mooney viscosity being 53, the molecular weight distribution being 2.6, and the gel content being 0.

[0040] Example 4

[0041] The difference from Example 1 is only that: a carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride (wherein, disulfur dichloride is 0.024 g, aluminum trichloride is 0.024 g, and carbon tetrachloride is 0.24 g) is added to obtain rare-earth cis-1,4-polybutadiene rubber, with a conversion rate of 96.7%, the content of cis-1,4 structure in the polymer being 97.3%, the Mooney viscosity being 56, the molecular weight distribution being 2.7, and the gel content being 0.

[0042] Example 5

[0043] The difference from Example 1 is only that: a carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride (wherein, disulfur dichloride is 0.048 g, aluminum trichloride is 0.024 g, and carbon tetrachloride is 0.18 g) is added to obtain rare-earth cis-1,4-polybutadiene rubber, with a conversion rate of 97.5%, the content of cis-1,4 structure in the polymer being 97.7%, the Mooney viscosity being 61, the molecular weight distribution being 2.8, and the gel content being 0.

[0044] Example 6

[0045] The difference from Example 1 is only that: a carbon tetrachloride solution of a complex of disulfur dichloride and aluminum trichloride (wherein, disulfur dichloride is 0.096 g, aluminum trichloride is 0.048 g, and carbon tetrachloride is 0.36 g) is added to obtain rare-earth cis-1,4-polybutadiene rubber, with a conversion rate of 98.2%, the content of cis-1,4 structure in the polymer being 97.1%, the Mooney viscosity being 72, the molecular weight distribution being 2.9, and the gel content being trace.

[0046] Example 7

[0047] The difference from Example 1 is only that: the temperature of the branching reaction is 20 °C to obtain rare-earth cis-1,4-polybutadiene rubber, with a conversion rate of 96.5%, the content of cis-1,4 structure in the polymer being 96.3%, the Mooney viscosity being 51, the molecular weight distribution being 2.6, and the gel content being 0.

[0048] Example 8

[0049] It is only different from Example 1 in that: the branching reaction temperature is 35 °C, and rare earth cis-1,4-polybutadiene rubber is obtained, with a conversion rate of 96.4%, the content of cis-1,4 structure in the polymer being 95.8%, the Mooney viscosity being 56, the molecular weight distribution being 2.8, and the gel content being 0.

[0050] Example 9

[0051] It is only different from Example 1 in that: the branching reaction temperature is 75 °C, and rare earth cis-1,4-polybutadiene rubber is obtained, with a conversion rate of 97.1%, the content of cis-1,4 structure in the polymer being 97.5%, the Mooney viscosity being 69, the molecular weight distribution being 2.9, and the gel content being 0.

[0052] Example 10

[0053] It is only different from Example 1 in that: the branching reaction temperature is 20 °C, and rare earth cis-1,4-polybutadiene rubber is obtained, with a conversion rate of 96.5%, the content of cis-1,4 structure in the polymer being 97.9%, the Mooney viscosity being 75, the molecular weight distribution being 3.0, and the gel content being 0.

[0054] Example 11

[0055] It is only different from Example 1 in that: 5.00 mmol of diisobutylaluminum hydride and 1.39 mmol of diisobutylaluminum chloride are used to obtain rare earth cis-1,4-polybutadiene rubber, with a conversion rate of 96.3%, the content of cis-1,4 structure in the polymer being 98.0%, the Mooney viscosity being 85, the molecular weight distribution being 2.9, and the gel content being 0.

[0056] Example 12

[0057] It is only different from Example 1 in that: 0.83 mmol of neodymium neodecanoate, 8.34 mmol of diisobutylaluminum hydride, and 1.67 mmol of diisobutylaluminum chloride are used for polymerization reaction at 35 °C for 6 h to obtain rare earth cis-1,4-polybutadiene rubber, with a conversion rate of 96.3%, the content of cis-1,4 structure in the polymer being 95.4%, the Mooney viscosity being 35, the molecular weight distribution being 2.6, and the gel content being 0.

[0058] Comparative Example 1

[0059] It is different from Example 1 in that: no branching agent is added. The conversion rate of the product is 96.8%, the content of cis-1,4 structure in the polymer being 96.4%, the Mooney viscosity being 29, the molecular weight distribution being 2.1, and the gel content being 0.

[0060] Comparative Example 2

[0061] It is different from Example 2 in that: no branching agent is added. The conversion rate of the product is 96.8%, the content of cis-1,4 structure in the polymer being 97.9%, the Mooney viscosity being 49, the molecular weight distribution being 2.4, and the gel content being 0.

[0062] Comparative Example 3

[0063] The difference from Example 3 is that no branching agent was added. The Mooney viscosity is 48 and the molecular weight distribution is 2.4.

[0064] Comparative Example 4

[0065] The difference from Example 4 is that no branching agent was added. The Mooney viscosity is 49 and the molecular weight distribution is 2.5.

[0066] Comparative Example 5

[0067] The difference from Example 5 is that no branching agent was added. The Mooney viscosity is 47 and the molecular weight distribution is 2.5.

[0068] Comparative Example 6

[0069] The difference from Example 6 is that no branching agent was added. The Mooney viscosity is 49 and the molecular weight distribution is 2.4.

[0070] Comparative Example 7

[0071] The difference from Example 7 is that no branching agent was added. The Mooney viscosity is 47 and the molecular weight distribution is 2.4.

[0072] Comparative Example 8

[0073] The difference from Example 8 is that no branching agent was added. The Mooney viscosity is 49 and the molecular weight distribution is 2.6.

[0074] Comparative Example 9

[0075] The difference from Example 9 is that no branching agent was added. The Mooney viscosity is 49 and the molecular weight distribution is 2.4.

[0076] Comparative Example 10

[0077] The difference from Example 10 is that no branching agent was added. The Mooney viscosity is 50 and the molecular weight distribution is 2.6.

[0078] Comparative Example 11

[0079] The difference from Example 11 is that no branching agent was added. The product conversion rate is 96.5%, the cis-1,4 structure content of the polymer is 98.1%, the Mooney viscosity is 55, the molecular weight distribution is 2.3, and the gel content is 0.

[0080] Comparative Example 12

[0081] The difference from Example 12 is that no branching agent was added. The product conversion rate was 94.7%, the content of cis-1,4 structure in the polymer was 95.5%, the Mooney viscosity was 29, the molecular weight distribution was 2.1, and the gel content was 0.

[0082] Comparative Example 13

[0083] The difference from Example 1 is only that the added branching agent is 0.12 g of disulfur dichloride.

[0084] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0085] According to the embodiments and comparative examples of the present invention, the content of cis-1,4 structure, Mooney viscosity, molecular weight distribution and gel content of the polymer were tested. It can be found that the content of cis-1,4 structure in the polymer before and after branching did not change much; the gel content did not increase significantly, avoiding the strong gelation tendency and the easy formation of local gel clusters when using disulfur dichloride to prepare branched rare earth cis-polybutadiene rubber in the conventional technology; the Mooney viscosity increased significantly, avoiding the operation that the rubber solution of rare earth cis-polybutadiene rubber needs to remove small molecule volatiles before the branching reaction, and also avoiding the problem that disulfur dichloride is extremely easy to form cyclic small molecule products with the residual butadiene in the rubber solution and cannot effectively form a branched structure.

[0086] In summary, the rare earth cis-polybutadiene rubber prepared by this method has the advantages of a narrow molecular weight distribution width, a long-chain branched structure, cold flow resistance, and a low gel content. It has excellent comprehensive properties and broad application prospects.

[0087] Although this specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what is claimed, but are mainly used to describe the characteristics of specific embodiments of a particular invention. Certain features described in multiple embodiments in this specification can also be combined and implemented in a single embodiment. On the other hand, various features described in a single embodiment can also be separately implemented in multiple embodiments or implemented in any suitable sub-combination. In addition, although features may function in certain combinations as described above and are even initially claimed as such, one or more features from the claimed combination can in some cases be removed from the combination, and the claimed combination can be directed to a sub-combination or a variant of the sub-combination.

[0088] Similarly, although the operations are depicted in the drawings in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or sequentially, or that all illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Additionally, the separation of various system modules and components in the above-described embodiments should not be understood to be required in all embodiments, and it should be understood that the program components and systems described can generally be integrated together in a single software product or packaged into multiple software products.

[0089] Accordingly, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the acts recited in the claims can be performed in a different order and still achieve the desired result. Additionally, the processes depicted in the figures are not necessarily in the particular order or sequential order shown to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0090] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0091] The above are only specific embodiments of the present application, which enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing rare earth butadiene rubber, characterized in that: The preparation method comprises the following steps: Step S1, taking butadiene, an organic solvent and a rare earth catalyst to perform a polymerization reaction to obtain a rubber polymer; Step S2, taking a branching agent and performing a branching reaction in the rubber polymer, and then adding a terminator to obtain the rare earth butadiene rubber; wherein the branching agent comprises a carbon tetrachloride solution of a disulfur dichloride and an aluminum trichloride complex, the molar ratio of the disulfur dichloride to the aluminum trichloride is 0.2-1.5:1, and the weight of the carbon tetrachloride accounts for 40-98wt% of the branching agent.

2. The method for preparing rare earth butadiene rubber according to claim 1, characterized in that: In the step S2, the branching reaction temperature is 20-100° C., and the reaction time is 10-120 min.

3. The method for preparing rare earth butadiene rubber according to claim 1, characterized in that: In the step S1, the organic solvent is hexane, and the polymerization reaction is carried out under a nitrogen atmosphere.

4. The method for preparing rare earth butadiene rubber according to claim 1, characterized in that: In step S1, the rare earth catalyst includes a rare earth compound and an alkyl aluminum, the rare earth compound is selected from one or more of neodymium neodecanoate, neodymium isooctanoate or neodymium phosphate, the molar ratio of the rare earth compound to the alkyl aluminum is 0.02-0.25:1, the alkyl aluminum is a mixture of diisobutylaluminum hydride and diisobutylaluminum chloride, and the molar ratio of the diisobutylaluminum hydride to the diisobutylaluminum chloride is 4-15:

1.

5. The method for preparing rare earth butadiene rubber according to claim 1, characterized in that: In the step S1, the weight ratio of the butadiene to the organic solvent is 0.12-0.30:1 in weight percentage.

6. The method for preparing rare earth butadiene rubber according to claim 1, characterized in that: In the step S1, the reaction temperature of the polymerization reaction is 20-90° C., and the reaction time is 1-10 hours.

7. A rare earth butadiene rubber, characterized in that: The rare earth cis-1,4-dione rubber is a rare earth cis-1,4-dione rubber obtained by the method for preparing the rare earth cis-1,4-dione rubber according to any one of claims 1 to 6.

8. The rare earth butadiene rubber according to claim 7, characterized in that: The content of cis-1,4 structured cis-1,4-butadiene rubber in the rare earth cis-1,4-butadiene rubber is 95-98%, the Mooney viscosity of the rare earth cis-1,4-butadiene rubber is 35-80, and the molecular weight distribution width coefficient PDI is 2-3.

9. An application of rare earth butadiene rubber in the field of tires, conveyor belts or shoemaking, characterized in that: The rare earth butadiene rubber is the rare earth butadiene rubber according to claim 7 or 8.

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