Highly transparent block-type solution-polymerized styrene-butadiene rubber and preparation method thereof

Abstract

The present invention relates to the technical field of synthetic rubber, and is a highly transparent block type solution polymerized styrene butadiene rubber and a preparation method thereof, wherein the highly transparent block type solution polymerized styrene butadiene rubber is obtained by the following method: the first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator one, and structure regulator two to a polymerization kettle under nitrogen protection, and add an initiator alkyl lithium at a temperature of 40 to 60°C to initiate a reaction; the second step is to continue the reaction for 20 minutes to 2.5 hours at a temperature of 90 to 125°C, and then add a required amount of terminator to the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block type solution polymerized styrene butadiene rubber. The highly transparent block type solution polymerized styrene butadiene rubber preparation method of the present invention has a simple process, is easy to design a polymer molecular weight, is easy to control a polymer microstructure, is suitable for industrial large-scale production, and the prepared transparent block type solution polymerized styrene butadiene rubber has excellent transparency.

Description

Technical Field

[0001] The invention relates to the technical field of synthetic rubber, in particular to a highly transparent block type solution-polymerized styrene-butadiene rubber and a preparation method thereof. Background Art

[0002] The development of solution styrene butadiene rubber can be divided into three generations: the first generation of products was developed by Phillips and Firestone in the 1960s. The product's resilience, wear resistance and hysteresis loss performance were better than ESBR, but the processing performance and anti-slip performance were poor. The second generation of SSBR, which was put into production in the early 1980s, took into account the rolling resistance and anti-slip performance of rubber through chain end modification including coupling and reasonable adjustment of the content and sequence distribution of styrene and vinyl segments. The second generation of SSBR has been widely used, and representative products include Shell's Cariflex S-1215 and Japan JSR's SL series tin-coupled SSBR. The third generation of SSBR is regarded as a broad concept. It uses the concept of integrated rubber to maximize the comprehensive performance of rubber through the optimization of molecular design and chain structure. At present, the third generation of SSBR includes: ① Styrene-isoprene-butadiene terpolymer (SIBR) with isoprene chain ends introduced into the macromolecular chain. ② SSBR containing block sequence structure distribution, its essence is to maximize the comprehensive performance of rubber through the optimized combination of molecular design and chain structure.

[0003] Copolymerization refers to the reaction of polymerizing two or more compounds into one substance under certain conditions. According to the number of monomer types, it can be divided into binary and ternary copolymers; according to the different molecular structures of the polymer, it can be divided into random copolymerization, block copolymerization, alternating copolymerization and graft copolymerization. Random copolymerization refers to the random arrangement of monomers on the macromolecular chain, the random distribution of monomers on the main chain, and no monomer can form a separate long chain segment on the molecular chain. Block copolymers, also known as mosaic copolymers, are a special polymer prepared by connecting two or more polymer segments with different properties. Block polymers with specific structures will show different properties from simple linear polymers, many random copolymers and even homopolymer mixtures. At present, in the field of butadiene-styrene series rubber synthesis, block rubber products mainly involve thermoplastic elastomer SBS and block-type solution-polymerized styrene-butadiene rubber. Among them, SBS is mainly prepared by changing the order of adding materials using a two-step method, a coupling method or a three-step method, and the resulting polymer is a thermoplastic elastomer. In recent years, the research hotspots of solution styrene butadiene rubber (SSBR) in China have mainly focused on the research of new initiators, regulators, functionalization, end group modification and molecular structure design; the overall development trend of foreign SSBR technology is: environmental protection, high performance and special materials.

[0004] Traditional plastic modification and sole materials can no longer meet current needs. In the future, they will develop in the direction of being more functional, lightweight, intelligent and environmentally friendly. With the continuous development of synthesis technology, new materials with better performance have emerged in recent years, such as solution polymerized styrene butadiene rubber (SSBR). At present, one of the research directions of the preparation technology of solution polymerized styrene butadiene rubber is to synthesize block-type solution polymerized styrene butadiene rubber with adjustable sequence structure distribution. Block-type solution polymerized styrene butadiene rubber is widely used in shoemaking, plastic modification and other rubber products industries due to its unique properties. For the synthesis of block solution polymerized styrene butadiene copolymers, most research institutions use butyl lithium as the initiator and cyclohexane as the solvent. Through the performance study of block styrene butadiene polymers, it can be seen that due to the different structural regulators, different feeding orders and different synthesis process parameters used by various research institutions, the main microstructure indicators combined with styrene content, vinyl content, block styrene content, etc. have great differences. However, the currently published literature and patents lack the description and research of the preparation technology of solution polymerized styrene butadiene rubber with high transparency. In addition, the essence of block solution styrene butadiene rubber is to maximize the comprehensive performance of rubber through the optimized combination of molecular design and chain structure, but the effective control of block styrene content within a certain vinyl content range, sequence structure regulation based on suitable structure regulators, and Mooney stabilization control technology are key technical issues that need to be solved urgently. Summary of the invention

[0005] The invention provides a highly transparent block type solution polymerized styrene butadiene rubber and a preparation method thereof, which overcomes the above-mentioned deficiencies of the prior art and can effectively solve the problems that the existing block type solution polymerized styrene butadiene rubber has low transparency and the existing block type solution polymerized styrene butadiene rubber synthesis method lacks effective control over the block styrene content.

[0006] One of the technical solutions of the present invention is achieved by the following measures: a highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0007] The first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add initiator alkyl lithium at a temperature of 40°C to 60°C to initiate the reaction; the second step is to continue the reaction at a temperature of 90°C to 125°C for 20min to 2.5h, and then add the required amount of terminator into the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0008] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0009] The above-mentioned hydrocarbon solvent is one of cyclopentane, cyclohexane, n-pentane and n-hexane, the mass ratio of styrene monomer and 1,3-butadiene monomer is 4:6 to 5:5, and the ratio of the total amount of styrene monomer and 1,3-butadiene monomer to the hydrocarbon solvent is 1:9 to 2:8.

[0010] The alkyl lithium initiator is one of n-butyl lithium, sec-butyl lithium and tert-butyl lithium, and the amount of the alkyl lithium used is 0.5 mmol to 1.2 mmol per 100 g of the total amount of styrene monomer and 1,3-butadiene monomer.

[0011] The structure regulator 1 is one of tetrahydrofuran, 2,5-dimethylfuran and 2,2-di(2-furyl)propane, and the mass ratio of the structure regulator 1 to the hydrocarbon solvent is 0.2:1000 to 3:1000.

[0012] The second structural regulator is one of ethyl tetrahydrofurfuryl ether, 2-tert-butyloxymethyltetrahydrofuran and sodium dodecylbenzenesulfonate, and the molar ratio of the second structural regulator to the initiator alkyl lithium is 1:10 to 1:1.

[0013] The terminator is an alcohol substance or a silicon-halogen bond compound, and the molar ratio of the added amount of the terminator to the alkyl lithium is 1:1 to 2:1.

[0014] The alcohol substance is one of ethanol, ethylene glycol, glycerol and isopropanol.

[0015] The general structural formula of the above silicon-halogen bond compound is SiXM3, wherein X is one of F, Cl, Br, and I, and M is one of methyl, ethyl, and isopropyl.

[0016] In the above-mentioned high-transparency block solution styrene butadiene rubber, the bound styrene content accounts for 40% to 50% of the total weight of the polymer, the vinyl content accounts for 20% to 40% of the total amount of 1,3-butadiene in the polymer, the block styrene content accounts for 4% to 20% of the total weight of the polymer, the Mooney viscosity is 10 to 110, and the molecular weight is 80,000 to 200,000.

[0017] The second technical solution of the present invention is achieved by the following measures: A method for preparing a highly transparent block-type solution-polymerized styrene-butadiene rubber by implementing one of the above technical solutions is carried out as follows:

[0018] The first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add alkyl lithium as an initiator at a temperature of 40° C. to 60° C. to initiate the reaction;

[0019] In the second step, the reaction is continued at a temperature of 90° C. to 125° C. for 20 minutes to 2.5 hours, and then a required amount of terminator is added to the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0020] The method for preparing the highly transparent block-type solution-polymerized styrene-butadiene rubber of the invention has simple process, easy design of polymer molecular weight, easy control of polymer microstructure, and is suitable for industrial large-scale production. The prepared transparent block-type solution-polymerized styrene-butadiene rubber has excellent transparency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 This is a gel permeation chromatogram of the highly transparent block-type solution-polymerized styrene-butadiene rubber prepared in Example 3 of the present invention, wherein the abscissa is time and the ordinate is molecular weight.

[0022] Attached Figure 2 is the nuclear magnetic vibration of the highly transparent block-type solution-polymerized styrene-butadiene rubber prepared in Example 4 of the present invention 1 H-NMR spectrum.

[0023] Attached Figure 3 This is a transparency test chart of the highly transparent block solution-polymerized styrene-butadiene rubber prepared in Example 3 of the present invention, the commercially available block solution-polymerized styrene-butadiene rubber and the thermoplastic elastomer SBS, wherein the abscissa is the wavelength and the ordinate is the transmittance. DETAILED DESCRIPTION

[0024] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; the normal temperature and room temperature in the present invention generally refer to the temperature of 15°C to 25°C, and are generally defined as 25°C.

[0025] The present invention will be further described below in conjunction with embodiments:

[0026] Embodiment 1: This highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0027] The first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add alkyl lithium as an initiator at a temperature of 40° C. to 60° C. to initiate the reaction;

[0028] In the second step, the reaction is continued at a temperature of 90° C. to 125° C. for 20 minutes to 2.5 hours, and then a required amount of terminator is added to the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0029] The above-mentioned hydrocarbon solvent is one of cyclopentane, cyclohexane, n-pentane and n-hexane, the mass ratio of styrene monomer and 1,3-butadiene monomer is 4:6 to 5:5, and the ratio of the total amount of styrene monomer and 1,3-butadiene monomer to the hydrocarbon solvent is 1:9 to 2:8.

[0030] The alkyl lithium initiator is one of n-butyl lithium, sec-butyl lithium and tert-butyl lithium, and the amount of the alkyl lithium used is 0.5 mmol to 1.2 mmol per 100 g of the total amount of styrene monomer and 1,3-butadiene monomer.

[0031] The structure regulator 1 is one of tetrahydrofuran, 2,5-dimethylfuran and 2,2-di(2-furyl)propane, and the mass ratio of the structure regulator 1 to the hydrocarbon solvent is 0.2:1000 to 3:1000.

[0032] The second structural regulator is one of ethyl tetrahydrofurfuryl ether, 2-tert-butyloxymethyltetrahydrofuran and sodium dodecylbenzenesulfonate, and the molar ratio of the second structural regulator to the initiator alkyl lithium is 1:10 to 1:1.

[0033] The terminator is an alcohol substance or a silicon-halogen bond compound, and the molar ratio of the added amount of the terminator to the alkyl lithium is 1:1 to 2:1.

[0034] The alcohol substance is one of ethanol, ethylene glycol, glycerol and isopropanol.

[0035] The general structural formula of the above silicon-halogen bond compound is SiXM3, wherein X is one of F, Cl, Br, and I, and M is one of methyl, ethyl, and isopropyl.

[0036] In the above-mentioned high-transparency block solution styrene butadiene rubber, the bound styrene content accounts for 40% to 50% of the total weight of the polymer, the vinyl content accounts for 20% to 40% of the total amount of 1,3-butadiene in the polymer, the block styrene content accounts for 4% to 20% of the total weight of the polymer, the Mooney viscosity is 10 to 110, and the molecular weight is 80,000 to 200,000.

[0037] The invention uses hydrocarbon substances as solvents, 1,3-butadiene monomers and styrene monomers as raw materials, and alkyl lithium as initiator. Under the dual regulation of two structural regulators with different polarities, an intermittent polymerization mode is adopted to achieve the optimization of molecular design and chain structure by controlling the addition amount and ratio within a wide temperature range, so as to prepare a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0038] The present invention selects two types of structure regulators, wherein structure regulator 1 is a non-protonic ether with medium polarity, and structure regulator 2 is relatively polar and has large steric hindrance. The main functions of the structure regulator in the present invention are: 1. improving the polarity of the solvent; 2. adjusting the reactivity ratio of styrene and butadiene, changing the reactivity ratio of the two and thus changing the copolymerization mode of the two monomers; 3. causing the alkyl lithium initiator to produce polarization and solvation effects, playing a role in dissociation, and reducing the degree of association of lithium ions in the alkyl lithium; 4. improving the polymerization reaction rate. In the synthesis process, structure regulator 1 and structure regulator 2 interact with each other, wherein structure regulator 1 is a non-protonic ether with medium polarity, which can change the polarity of the solvent, but its regulating ability for vinyl is limited, and it tends to produce block copolymers, which can be beneficial to the formation of blocks to a certain extent within the low vinyl range. Structural regulator II has a large steric hindrance and a strong polarity, which can dissociate the initiator alkyl lithium and can complex with the active polybutadiene lithium chain ([PBLi]) to form a π-allyl lithium structure, which promotes the dissociation of active species and accelerates the polymerization reaction rate. For example, 2-tert-butyloxymethyltetrahydrofuran has a large volume and forms a large steric hindrance when complexed with [PBLi]. This steric hindrance makes it easier for 1,3-butadiene monomers to generate 1,2-structured products when inserted between C-Li bonds. Therefore, adding structural regulator II can both increase the polymerization reaction rate and increase the vinyl content in the polymer.

[0039] The present invention uses anionic polymerization chain end active termination technology to terminate the polymerization reaction, and uses alcohol substances or silicon-halogen bond compounds as terminators to effectively terminate the chain end active center, thereby preventing it from contacting water, air, esters, phenols and other substances to produce coupled macromolecules.

[0040] Embodiment 2: As the optimization of the above embodiment, the highly transparent block type solution polymerized styrene butadiene rubber is obtained by the following method:

[0041] The first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add initiator alkyl lithium at a temperature of 40°C or 60°C to initiate the reaction; the second step is to continue the reaction at a temperature of 90°C or 125°C for 20 minutes or 2.5 hours, and then add the required amount of terminator into the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0042] The above hydrocarbon solvent is one of cyclopentane, cyclohexane, n-pentane and n-hexane, the mass ratio of styrene monomer and 1,3-butadiene monomer is 4:6 or 5:5, and the ratio of the total amount of styrene monomer and 1,3-butadiene monomer to the hydrocarbon solvent is 1:9 or 2:8.

[0043] The alkyl lithium initiator is one of n-butyl lithium, sec-butyl lithium and tert-butyl lithium, and the amount of the alkyl lithium used is 0.5 mmol or 1.2 mmol per 100 g of the total amount of styrene monomer and 1,3-butadiene monomer.

[0044] The structure regulator 1 is one of tetrahydrofuran, 2,5-dimethylfuran and 2,2-di(2-furyl)propane, and the mass ratio of the structure regulator 1 to the hydrocarbon solvent is 0.2:1000 or 3:1000.

[0045] The second structural regulator is one of ethyl tetrahydrofurfuryl ether, 2-tert-butyloxymethyltetrahydrofuran and sodium dodecylbenzenesulfonate, and the molar ratio of the second structural regulator to the initiator alkyl lithium is 1:10 or 1:1.

[0046] The terminator is an alcohol substance or a silicon-halogen bond compound, and the molar ratio of the added amount of the terminator to the alkyl lithium is 1:1 or 2:1.

[0047] The alcohol substance is one of ethanol, ethylene glycol, glycerol and isopropanol.

[0048] The general structural formula of the above silicon-halogen bond compound is SiXM3, wherein X is one of F, Cl, Br, and I, and M is one of methyl, ethyl, and isopropyl.

[0049] In the above-mentioned highly transparent block solution styrene butadiene rubber, the bound styrene content accounts for 40% or 50% of the total weight of the polymer, the vinyl content accounts for 20% or 40% of the total amount of 1,3-butadiene in the polymer, the block styrene content accounts for 4% or 20% of the total weight of the polymer, the Mooney viscosity is 10 or 110, and the molecular weight is 80,000 or 200,000.

[0050] Embodiment 3: This highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0051] The first step is to add 162 g of styrene monomer, 190 g of 1,3-butadiene monomer, 2000 g of cyclopentane, 2.0 g of tetrahydrofuran and 0.37 g of 2-tert-butoxymethyltetrahydrofuran (the molar ratio of 2-tert-butoxymethyltetrahydrofuran to n-butyl lithium is 4:5) into a polymerization kettle under nitrogen protection, and add 2.93 mmol of n-butyl lithium as an initiator at a temperature of 50°C to initiate the reaction;

[0052] In the second step, the reaction was continued at 90°C for 2 hours, and then 0.16 g of terminator ethanol (the molar ratio of ethanol to n-butyl lithium was 6:5) was added into the polymerization kettle to terminate the reaction, thereby obtaining highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0053] The prepared highly transparent block-type solution-polymerized styrene-butadiene rubber was dried and weighed. The monomer conversion rate was measured and calculated to be about 95%, the number average molecular weight Mn was 115,000, the molecular weight distribution index Mw / Mn was 1.03, and the Mooney viscosity was 44.1. The highly transparent block-type solution-polymerized styrene-butadiene rubber had a combined styrene content of 45.5%wt (based on the total weight of the polymer), a block styrene content of 14.2%wt (based on the total weight of the polymer), and a vinyl content of 34.6%wt (based on the total amount of polymerized 1,3-butadiene).

[0054] Embodiment 4: This highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0055] In the first step, under nitrogen protection, 162 g of styrene monomer, 190 g of 1,3-butadiene monomer, 2000 g of cyclopentane, 3.0 g of 2,2-di(2-furyl)propane, and 0.22 g of ethyl tetrahydrofurfuryl ether (the molar ratio of ethyl tetrahydrofurfuryl ether to n-butyl lithium is 3:5) are added to the polymerization kettle, and 2.8 mmol of n-butyl lithium as an initiator is added at a temperature of 50°C to initiate the reaction;

[0056] In the second step, the reaction was continued at 90°C for 2 hours, and then 0.64 g of the terminator triethylchlorosilane (the molar ratio of triethylchlorosilane to n-butyllithium was 6:5) was added into the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0057] The prepared highly transparent block-type solution-polymerized styrene-butadiene rubber was dried and weighed. The monomer conversion rate was measured and calculated to be about 98%, the number average molecular weight Mn was 125,000, the molecular weight distribution index Mw / Mn was 1.03, and the Mooney viscosity was 45.2. The highly transparent block-type solution-polymerized styrene-butadiene rubber had a combined styrene content of 45.1%wt (based on the total weight of the polymer), a block styrene content of 12.6%wt (based on the total weight of the polymer), and a vinyl content of 31.2%wt (based on the total amount of polymerized 1,3-butadiene).

[0058] Embodiment 5: This highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0059] In the first step, under nitrogen protection, 162 g of styrene monomer, 190 g of 1,3-butadiene monomer, 2000 g of cyclopentane, 4.0 g of 2,5-dimethylfuran and 0.36 g of sodium dodecylbenzene sulfonate (the molar ratio of ethyl tetrahydrofurfuryl ether to sec-butyl lithium is 2:5) are added to the polymerization kettle in sequence, and 2.59 mmol of sec-butyl lithium as an initiator is added at a temperature of 50°C to initiate the reaction;

[0060] In the second step, the reaction was continued at 90°C for 2 hours, and then 0.15 g of terminator ethanol (the molar ratio of ethanol to sec-butyl lithium was 6:5) was added into the polymerization kettle to terminate the reaction, thereby obtaining highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0061] The prepared highly transparent block-type solution-polymerized styrene-butadiene rubber was dried and weighed. The monomer conversion rate was measured and calculated to be about 98%, the number average molecular weight Mn was 136,000, the molecular weight distribution index Mw / Mn was 1.02, and the Mooney viscosity was 50. The highly transparent block-type solution-polymerized styrene-butadiene rubber had a styrene content of 45.80%wt (based on the total weight of the polymer), a block styrene content of 9.2%wt (based on the total weight of the polymer), and a vinyl content of 28.9%wt (based on the total amount of polymerized 1,3-butadiene).

[0062] Embodiment 6: This highly transparent block type solution-polymerized styrene-butadiene rubber is obtained by the following method:

[0063] The first step is to add 3500 g of styrene monomer, 4100 g of 1,3-butadiene monomer, 43000 g of n-hexane, 107.5 g of tetrahydrofuran, and 2.43 g of 2-tert-butoxymethyltetrahydrofuran (the molar ratio of 2-tert-butoxymethyltetrahydrofuran to tert-butyl lithium is 1:5) to a polymerization kettle under nitrogen protection, and add 50.39 mmol of initiator tert-butyl lithium at a temperature of 45°C to initiate the reaction;

[0064] In the second step, the reaction was continued at a temperature of 110°C for 1 hour, and then 3.25 g of terminator ethanol (the molar ratio of ethanol to tert-butyl lithium was 7:5) was added to the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

[0065] The prepared highly transparent block-type solution-polymerized styrene-butadiene rubber was dried and weighed. The monomer conversion rate was measured and calculated to be about 98%, the number average molecular weight Mn was 151,000, the molecular weight distribution index Mw / Mn was 1.02, and the Mooney viscosity was 56. The highly transparent block-type solution-polymerized styrene-butadiene rubber had a styrene content of 45.9%wt (based on the total weight of the polymer), a block styrene content of 15.7%wt (based on the total weight of the polymer), and a vinyl content of 30.7%wt (based on the total amount of polymerized 1,3-butadiene).

[0066] The number average molecular weight Mn and molecular weight distribution index (Mw / Mn) of the highly transparent block type solution polymerized styrene butadiene rubber prepared in Examples 3 to 6 of the present invention were measured by gel permeation chromatography (GPC); the bound styrene content and vinyl content of the highly transparent block type solution polymerized styrene butadiene rubber were measured by Fourier transform infrared spectrometer (FTIR); the block styrene content was measured by nuclear magnetic vibration 1The results were obtained by H-NMR analysis and Mooney viscosity was obtained by Mooney viscometer.

[0067] Figure 1 The gel permeation chromatogram of the highly transparent block-type solution-polymerized styrene-butadiene rubber prepared in Example 3 of the present invention is shown in FIG. Figure 1 It can be seen from the gel permeation chromatogram of the highly transparent block-type solution-polymerized styrene-butadiene rubber prepared in Example 3 that a single-peak molecular weight distribution is shown, the peak shape is symmetrical, and only a very small amount of "double coupling peak" is contained. The narrow molecular weight distribution indicates that the present invention has few side reactions, and the coupling macromolecules produced by the polymer contacting water, air, esters, phenols and the like are effectively avoided during the reaction.

[0068] Figure 2 The highly transparent block-type solution-polymerized styrene-butadiene rubber prepared in Example 4 of the present invention 1 Based on the H-NMR spectrum and the calculation method provided in the literature “Microstructure Regulation of Styrene-Butadiene Copolymers and Design and Synthesis of Solution Polymerized Butadiene Styrene (SSBR)” (Zhao Fangyuan. Microstructure Regulation of Styrene-Butadiene Copolymers and Design and Synthesis of Solution Polymerized Butadiene Styrene (SSBR) [D]. Beijing University of Chemical Technology), it was calculated that the randomness R of the high-transparent block type solution polymerized butadiene styrene rubber was 74.2%, and the block styrene content was 12.6%.

[0069] Transparency test:

[0070] The highly transparent block type solution polymerized styrene butadiene rubber prepared in Example 3, the commercially available block type solution polymerized styrene butadiene rubber and the thermoplastic elastomer SBS were cut into slices with a thickness of 1 mm, and their direct light transmittance in the wavelength range of 380 nm to 810 nm was tested by a visible spectrometer (the light transmittance at each wavelength was measured 4 times and the average value was taken). The test results are shown in FIG. Figure 3 .Depend on Figure 3 It can be seen that the highly transparent block-type solution-polymerized styrene-butadiene rubber of the present invention has higher transparency than the commercially available block-type solution-polymerized styrene-butadiene rubber, and its direct light transmittance within the wavelength range of 380nm to 810nm is higher than 45%, and the direct light transmittance within the wavelength range of 600nm to 810nm is above 60%. Therefore, the highly transparent block-type solution-polymerized styrene-butadiene rubber of the present invention can be widely used in the shoemaking industry to improve the transparency and glossiness of shoe products, thereby driving the development of the domestic high-end shoemaking industry, and then can be promoted and applied to other rubber products or plastic modification, and give play to its unique application value.

[0071] In summary, the method for preparing the highly transparent block-type solution-polymerized styrene-butadiene rubber of the present invention is simple in process, the polymer molecular weight is easy to design, the polymer microstructure is easy to control, and it is suitable for industrial large-scale production. The prepared transparent block-type solution-polymerized styrene-butadiene rubber has excellent transparency and can be widely used in the shoemaking industry, and can significantly improve the transparency of rubber products.

Claims

1. A highly transparent block-type solution-polymerized styrene-butadiene rubber, characterized in that The method is as follows: the first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add alkyl lithium as an initiator at a temperature of 40°C to 60°C to initiate the reaction; the second step is to continue the reaction at a temperature of 90°C to 125°C for 20 minutes to 2.5 hours, and then add a required amount of terminator into the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber; wherein the mass ratio of styrene monomer to 1,3-butadiene monomer is 4:6 to 5:5; the hydrocarbon solvent is one of cyclopentane, cyclohexane, n-pentane and n-hexane, and the mass ratio of the total amount of styrene monomer and 1,3-butadiene monomer to the hydrocarbon solvent is 1:9 to 2:8; the initiator alkyl lithium is added to the polymerization kettle to initiate the reaction; The alkyl lithium is one of n-butyl lithium, sec-butyl lithium and tert-butyl lithium, and the amount of alkyl lithium is 0.5 mmol to 1.2 mmol per 100 g of the total amount of styrene monomer and 1,3-butadiene monomer; the structure regulator one is one of tetrahydrofuran, 2,5-dimethylfuran, 2,2-di(2-furyl)propane, and the mass ratio of the structure regulator one to the hydrocarbon solvent is 0.2:1000 to 3:1000; the structure regulator two is 2-tert-butoxymethyltetrahydrofuran, and the molar ratio of the structure regulator two to the initiator alkyl lithium is 1:10 to 1:1; the terminator is a silicon-halogen bond compound, and the general structural formula of the silicon-halogen bond compound is SiXM3, wherein X is one of F, Cl, Br, I, and M is one of methyl, ethyl, and isopropyl.

2. The highly transparent block-type solution-polymerized styrene-butadiene rubber according to claim 1, characterized in that The molar ratio of the added amount of the terminator to the alkyl lithium is 1:1 to 2:

1.

3. The highly transparent block-type solution-polymerized styrene-butadiene rubber according to claim 1 or 2, characterized in that In the highly transparent block solution styrene butadiene rubber, the bound styrene content accounts for 40% to 50% of the total weight of the polymer, the vinyl content accounts for 20% to 40% of the total amount of 1,3-butadiene in the polymer, the block styrene content accounts for 4% to 20% of the total weight of the polymer, the Mooney viscosity is 10 to 110, and the molecular weight is 80,000 to 200,000.

4. A method for preparing a highly transparent block-type solution-polymerized styrene-butadiene rubber according to claim 1, 2 or 3, characterized in that The process is carried out in the following steps: the first step is to add styrene monomer and 1,3-butadiene monomer, hydrocarbon solvent, structure regulator 1 and structure regulator 2 into a polymerization kettle under nitrogen protection, and add initiator alkyl lithium at a temperature of 40°C to 60°C to initiate the reaction; the second step is to continue the reaction at a temperature of 90°C to 125°C for 20 minutes to 2.5 hours, and then add the required amount of terminator into the polymerization kettle to terminate the reaction, thereby obtaining a highly transparent block-type solution-polymerized styrene-butadiene rubber.

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