Imidazole ionic liquid for trans-polybutadiene rubber mixing and preparation method and application thereof

Abstract

The application provides an imidazole ionic liquid for trans-polybutadiene rubber mixing, a preparation method and application thereof. The imidazole ionic liquid is named as MI, and X in the chemical formula is at least one of Br, Cl, I or F. The imidazole ionic liquid for trans-polybutadiene rubber mixing is used in wet mixing and premixing of trans-polybutadiene rubber. The application innovatively designs and synthesizes an imidazole ionic liquid MI which is soluble in alkaline water, and the MI shows good solubility to TBIR. After the MI is used to dissolve the TBIR, the wet premixing system of natural latex and magnesium hydroxide with water as a solvent is added, and the green wet premixing technology for TBIR (without organic solvent) is realized.

Description

Technical Field

[0001] This invention belongs to the field of rubber wet premixing technology, and particularly relates to an imidazole ionic liquid, its preparation method and application. Background Technology

[0002] Mixing is the first and most crucial step in the rubber compound processing and production process. Its task is to uniformly mix the raw rubber in the formula with various raw materials to produce a compound that meets the requirements. The mixing process not only affects the processing performance of the rubber but also significantly impacts the physical and mechanical properties of the compound and even the performance of the finished product. The concept of wet mixing technology was proposed by Cabot Corporation in 2001. It involves mixing latex-state rubber (natural or synthetic latex) with a pre-dispersed liquid dispersion system of reinforcing fillers. The reinforcing filler particles are dispersed within the latex system, forming a homogeneous liquid system. Then, flocculation and co-precipitation occur to form a rubber / filler composite material. Unlike traditional methods that use solid rubber and powdered fillers as raw materials and employ open mills or internal mixers for mechanical mixing, wet mixing overcomes some inherent drawbacks of dry mixing. The entire wet mixing process is carried out under liquid conditions. Firstly, it overcomes the pollution problem caused by the large amount of powdered fillers flying around in dry mixing processes, thus improving the working environment of the mixing process. Secondly, it reduces energy consumption in the mixing process, thus saving energy and reducing emissions. Finally, and most importantly, the rubber compound prepared using the wet mixing process is better suited to achieving superior overall physical properties. Specifically, compared to the solid-solid mixing of traditional dry mixing processes, the liquid-liquid mixing of wet mixing technology makes it easier to achieve pipelined transportation, continuous production, and automation, avoiding dust pollution and significantly reducing energy consumption and production costs. Wet mixing allows powdered fillers to be fully dispersed in the rubber, while the rubber macromolecules are not damaged by mechanical shearing and high-temperature thermal oxidation, resulting in high rubber strength, high elongation at break, good elasticity, and superior dynamic performance, thus improving the overall performance of the finished product.

[0003] Trans-butadiene-pentadiene rubber (TBIR) is a new generation of functional synthetic rubber jointly developed by Qingdao University of Science and Technology and Shandong Huaju Polymer Materials Co., Ltd. TBIR is a copolymeric polymer material with a high trans-1,4-structure, composed of isoprene and butadiene structural units. TBIR can improve the compatibility between natural rubber, cis-butadiene rubber, styrene-butadiene rubber, and other rubbers, improve the dispersibility of fillers in the compound, and help each rubber type exert its superior performance. In particular, TBIR-containing vulcanized rubber exhibits good fatigue performance, which has a positive effect on extending the service life of rubber vibration damping products. However, TBIR is a synthetic polymer material with low molecular polarity, making it difficult to dissolve in water-based solvents, which is not conducive to the development of wet processing technology.

[0004] Ionic liquids, also known as room-temperature ionic liquids or room-temperature molten salts, are generally composed of organic cations and inorganic / organic anions, and are liquid at or near room temperature. In 2002, Swatloski et al. used alkyl-substituted imidazole ionic liquids to dissolve and treat cellulose, finding that they had good solubility for cellulose. This property of imidazole ionic liquids provided a new approach for the dissolution of polymeric organic materials. However, existing imidazole ionic liquids have a weaker conjugation effect compared to MI (methyl ether ionization), and may not be able to dissolve TBIR (total tert-butyl irradiated liquid). Furthermore, existing imidazole particle liquids generally do not contain silyl ethoxy groups, and therefore cannot form chemical bonds with fillers such as magnesium hydroxide, nor do they modify the fillers. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide an imidazole ionic liquid for trans-butadiene rubber compounding, its preparation method and application.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] An imidazole-based ionic liquid for trans-butadiene-pentylene rubber compounding, the imidazole-based ionic liquid is named MI, and its chemical formula is as follows:

[0008]

[0009] In the formula, X is at least one of Br, Cl, I or F.

[0010] Under the same technical concept, the present invention also provides a method for preparing an imidazole ionic liquid for trans-butadiene rubber compounding, comprising the following steps:

[0011] (1) Synthesis of M intermediate:

[0012] Triarylimidazolium and tri-meta-aryl halogen were placed in a reaction vessel, copper iodide was added, along with a surfactant, carbonate and organic solvent. The mixture was stirred under a nitrogen atmosphere for 12-48 hours at a temperature of 60-120°C. The mixture was then filtered, and the lower clear liquid was concentrated and dried under vacuum to obtain aromatic imidazolium intermediate M.

[0013] The molar ratio of the triarylimidazolium, tri-meta-aryl halogen, copper iodide, surfactant, carbonate, and organic solvent is 3.0-3.5:1.0:0.5-1.0:0.5-1.0:5.0-8.0:150-600;

[0014] The chemical formula of the intermediate M is as follows:

[0015]

[0016] (2) Synthesis of MI from aromatic imidazole intermediate M:

[0017] Aromayl imidazole intermediate M and halopropyltriethoxysilane were placed in a reaction vessel and refluxed at 80-150℃ for 12-24 h. After the reaction was completed, excess halopropylsiloxysilane was rotary evaporated to obtain ionic liquid MI.

[0018] The molar ratio of the aromatic imidazole intermediate M to the halopropyltriethoxysilane is 1.0:3.1-6.0.

[0019] Preferably, the surfactant is at least one of dimethylethylenediamine, L-proline, or 1,2-cyclohexanediamine; the carbonate is at least one of potassium carbonate, sodium carbonate, or cesium carbonate; and the organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide, including dimethylethylenediamine, L-proline, or 1,2-cyclohexanediamine.

[0020] Under the same technical concept, the present invention also provides an application of an imidazole ionic liquid for trans-butadiene rubber compounding, wherein the imidazole ionic liquid for trans-butadiene rubber compounding is used in the wet compounding premixing of trans-butadiene rubber.

[0021] More preferably, the imidazole ionic liquid for trans-butadiene rubber compounding is used in special equipment or high-end track rubber vibration damping and flame retardant products.

[0022] Preferably, the wet compounding step of the trans-butadiene rubber is as follows:

[0023] (1) Mechanical stirring and ultrasonic treatment of natural rubber latex;

[0024] (2) Dissolve trans-butadiene rubber in an imidazole ionic liquid. After complete dissolution, slowly add it dropwise to an alkaline aqueous solution and stir until a stable trans-butadiene rubber ionic liquid aqueous solution is formed.

[0025] (3) Slowly add the trans-butadiene rubber ionic liquid aqueous solution to the natural rubber latex;

[0026] (4) Disperse magnesium hydroxide in distilled water, stir mechanically, and slowly and gradually transfer the well dispersed magnesium hydroxide aqueous solution into natural rubber latex;

[0027] (5) Heat the natural rubber latex to 40℃-60℃, mechanically stir and ultrasonically premix for 2h-10h. After the premixing is complete, add a weak acid to break the emulsion to obtain raw rubber. Wash the raw rubber thoroughly, and then vacuum dry the raw rubber at 20℃-35℃ for 96h-168h to obtain premixed trans-butadiene rubber masterbatch.

[0028] The premixing mechanism diagram of imidazole ionic liquids with TBIR and magnesium hydroxide for trans-butadiene rubber compounding is shown below. Figure 8As shown. The TBIR wet premixing technology is carried out in an alkaline aqueous solution and is a green chemical technology. The designed and synthesized MI can not only act as a solvent for TBIR, but the silyl ethoxy bond of MI can also undergo dehydration condensation and hydrogen bond self-assembly with magnesium hydroxide, which improves the dispersibility and stability of magnesium hydroxide in NR and TBIR, and synergistically promotes the compatibility of TBIR and filler.

[0029] Preferably, in the wet mixing process, the raw materials are proportioned in the following mass ratios:

[0030]

[0031] Preferably, the alkaline aqueous solution is an aqueous solution of sodium hydroxide or potassium hydroxide, and the solute to solvent ratio is (1-5) g / 10 mL; the weak acid is oxalic acid and / or acetic acid.

[0032] Preferably, the mechanical stirring speed in step (4) is 500 rpm to 2000 rpm, and the stirring time is 1 h to 2 h.

[0033] Preferably, the premixed trans-butadiene rubber obtained by the wet mixing premixing process is used to prepare vulcanized rubber, and the specific steps are as follows:

[0034] (1) Mix the premixed trans-butadiene rubber masterbatch evenly at a mixing temperature of 80℃-100℃;

[0035] (2) Add zinc oxide, stearic acid, antioxidant, carbon black, and silica, and mix at a low temperature for 3-5 minutes;

[0036] (3) Add sulfur and accelerator, mix for 3-5 minutes, mix at a temperature of 70℃-90℃, and pass through the open mill 3-5 times or make triangular wraps 3-5 times to obtain the two-stage compound rubber.

[0037] (4) After the compound obtained in step (3) is left to stand for at least 16 hours, vulcanized rubber is prepared according to the vulcanization conditions of vulcanization temperature of 145℃-155℃ and vulcanization time of TC90+(2-5)min.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) This invention innovatively designs and synthesizes an imidazole-based ionic liquid MI that is miscible with alkaline water, and MI exhibits good solubility for TBIR. After dissolving TBIR with MI, it is then added to a wet premixing system of natural latex and magnesium hydroxide using water as a solvent, realizing a green wet premixing technology for TBIR (without organic solvents). Simultaneously, the siloxyalkylene and nitrogen elements in MI can chemically bond with magnesium hydroxide and enhance hydrogen bonding, respectively, which is beneficial for filler dispersion and thus enhances the physical and mechanical properties of the rubber. Through this green wet premixing technology for TBIR, the fatigue life of flame-retardant rubber is extended.

[0040] (2) The preparation method of the present invention is simple and easy to operate, has high versatility, can be used with organic synthesis instruments and equipment, has high equipment versatility, and has good market application value in the rubber industry. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a chemical schematic diagram of the imidazole ionic liquid MI;

[0043] Figure 2 This is a schematic diagram of the synthesis mechanism of imidazole ionic liquid MI;

[0044] Figure 3 This is the NMR spectrum of the aromatic imidazole intermediate M;

[0045] Figure 4 This is a picture of a raw rubber sample of premixed trans-butadiene rubber from Example 1;

[0046] Figure 5 This is a sample image of the premixed trans-butadiene rubber masterbatch from Example 1;

[0047] Figure 6 This is a 10x magnified electron microscope image of the raw rubber of premixed trans-butadiene rubber from Example 1.

[0048] Figure 7 The image shows an electron microscope image of the raw rubber of the premixed trans-butadiene rubber from Example 1.

[0049] Figure 8 The diagram shows the premixing mechanism of imidazole ionic liquids with TBIR and magnesium hydroxide;

[0050] Figure 9 The images show the vulcanization curves of the rubber compounds in Example 1 and Comparative Example 1. Detailed Implementation

[0051] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0053] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0054] Example 1

[0055] An imidazole-based ionic liquid for trans-butadiene rubber compounding, the imidazole-based ionic liquid is named MI, and its chemical formula is as follows: Figure 1 As shown;

[0056] The preparation method of imidazole ionic liquids for trans-butadiene rubber compounding, and the synthesis mechanism circuit diagram are as follows: Figure 2 As shown, the specific steps are as follows:

[0057] Triarylimidazole (0.31 mol, 91.88 g) and 1,3,5-triiodobenzene (0.1 mol, 45.58 g) were placed in a reaction vessel, followed by copper iodide (0.06 mol, 11.43 g), L-proline (0.06 mol, 6.91 g), potassium carbonate (0.6 mol, 82.92 g), and then DMF (20 mol, 1462 g). After purging oxygen with nitrogen for 30 min, the reaction was stirred at 110 °C for 24 h under a nitrogen atmosphere. The mixture was filtered, the supernatant was collected, the solvent was concentrated, and the solution was dried under vacuum to obtain intermediate M.

[0058] The NMR spectrum of intermediate M is as follows Figure 3 As shown.

[0059] M (0.05 mol, 48.07 g) and chloropropyltriethoxysilane (0.25 mol, 60.2 g) were placed in a reaction vessel and refluxed at 80 °C for 12 h. After the reaction was completed, excess chloropropyltriethoxysilane was evaporated using a rotary evaporator to obtain the ionic liquid MI.

[0060] The wet premixing of TBIR with imidazole ionic liquid for trans-butadiene rubber compounding is performed using the following steps:

[0061] Take 150 parts by weight of natural rubber latex and mechanically stir and sonicate at 2000 rpm;

[0062] Take 10 parts of TBIR and dissolve it in 20 parts of imidazole ionic liquid. After complete dissolution, slowly add it dropwise to 10 parts of 1g / 5mL sodium hydroxide aqueous solution and stir until a stable solution is formed.

[0063] A stable TBIR ionic liquid aqueous solution was gradually and slowly added dropwise to natural rubber latex;

[0064] Take 80 parts by mass of magnesium hydroxide and disperse it in 200 parts of distilled water. Stir mechanically at 2000 rpm for 1 hour to make it uniformly dispersed in the aqueous solvent.

[0065] The well-dispersed magnesium hydroxide aqueous solution was slowly and gradually transferred into the natural rubber latex;

[0066] Heat to 60℃, mechanically stir and ultrasonically premix for 5 hours;

[0067] After complete premixing, 20 parts of acetic acid were added to break the emulsion, and the premixed raw rubber was thoroughly washed with distilled water. Then, the premixed rubber was vacuum dried at 30°C for 168 hours to obtain premixed trans-butadiene rubber masterbatch.

[0068] See the sample after wet premixing Figure 4 , 5 See electron micrograph of the sample. Figure 6 , 7 ,Depend on Figure 6 , 7 As can be seen, the filler exhibits a relatively uniform dispersion in the raw rubber, and the circled areas in the figure represent air bubbles.

[0069] The premixed trans-butadiene rubber masterbatch was used in the preparation of the rubber compound, as shown in Table 1, #2. The specific operating steps are as follows:

[0070] (1) Add the wet premixed masterbatch into a general rubber mixing equipment and mix evenly, with the mixing temperature controlled at 80℃-100℃.

[0071] (2) Add zinc oxide, stearic acid, antioxidant, carbon black, and silica, and mix at a low temperature for 3-5 minutes;

[0072] (3) Add sulfur and accelerator, mix for 3-5 minutes, mix at 70℃-90℃, pass through the open mill 3-5 times or make triangular wraps 3-5 times to obtain two-stage compound rubber.

[0073] After the compound obtained in step (3) is left to stand for 16 hours, vulcanized rubber is prepared according to the vulcanization conditions of vulcanization temperature 150℃±5℃ and vulcanization time TC90+(2-5)min.

[0074] Table 1 Rubber Formulation (parts by mass)

[0075]

[0076]

[0077] Comparative Example 1:

[0078] The rubber compound was prepared by wet process, and the remaining steps were the same as in Example 1. The formulation is shown in Table 1, 1#.

[0079] The vulcanization curves of compound rubber #1 and #2 are shown below. Figure 9 As shown in the figure, compared with ordinary rubber compounds, rubber compounds prepared using the wet premixing method exhibit the following characteristics: 1. The overall vulcanization curve trends remain largely consistent, with TS2 and TC90 remaining essentially unchanged. This indicates that rubber compounds prepared using the wet premixing method can maintain the original vulcanization process, which is beneficial for maintaining the consistency of the vulcanization process, the continuity of production operations, and the quality stability of the rubber compound. 2. The vulcanization curve of rubber compounds prepared using the wet premixing method is flatter, and the maximum torque value is also slightly higher. This suggests that the wet premixing technology has a positive effect on improving the conventional properties of the rubber compound, and the rubber compound is suitable for long-term storage.

[0080] Table 2 shows the physical, fatigue, and flame retardant properties of vulcanizates 1# and 2#. Compared to vulcanizate 1#, vulcanizate 2#, prepared using a wet premixing method, has the following main upgrades:

[0081] 1. The significant increase in tensile strength indicates an increase in the modulus of the vulcanizate, making it more resistant to deformation;

[0082] 2. Compression set is reduced, and resilience is improved;

[0083] The decrease in tanδ at 3.23℃ and 60℃ and the decrease in compression temperature rise indicate that the dynamic properties of the vulcanizate are improved and the internal loss is reduced. This indirectly reflects that, on the one hand, the dispersibility of the filler inside the vulcanizate is improved, resulting in fewer stress concentration points, and on the other hand, it may be due to the contribution of TBIR.

[0084] 4. Improved low-temperature performance indicates that wet-process premixed flame-retardant rubber exhibits stronger freeze resistance in low-temperature environments;

[0085] 5. Improved flexural fatigue performance helps solve the problem of poor fatigue performance of flame-retardant rubber; 6. Reduced maximum smoke density and heat release rate improve overall flame-retardant performance.

[0086] Table 2 Physical and flame retardant properties of vulcanizates

[0087] .

Claims

1. An imidazole-based ionic liquid for compounding trans-butadiene-pentadiene rubber, characterized in that, The imidazole ionic liquid is named MI, and its chemical formula is as follows: ； In the formula, X is at least one of Br, Cl, I or F.

2. A method for preparing an imidazole ionic liquid for trans-butadiene-pentadiene rubber compounding as described in claim 1, characterized in that, Includes the following steps: (1) Synthesis of intermediate M: Triarylimidazolium and tri-meta-aryl halogen were placed in a reaction vessel, copper iodide was added, along with a surfactant, carbonate and organic solvent. The mixture was stirred under a nitrogen atmosphere for 12-48 hours at a temperature of 60-120°C. The mixture was then filtered, and the lower clear liquid was concentrated and dried under vacuum to obtain aromatic imidazolium intermediate M. The molar ratio of the triarylimidazolium, tri-meta-aryl halogen, copper iodide, surfactant, carbonate, and organic solvent is 3.0-3.5:1.0:0.5-1.0:0.5-1.0:5.0-8.0:150-600; The chemical formula of the intermediate M is as follows: ； (2) Synthesis of MI from aromatic imidazole intermediate M: Aromatic imidazole intermediate M and halopropyltriethoxysilane were placed in a reaction vessel and refluxed at 80℃-150℃ for 12h-24h. After the reaction was completed, excess halopropylsiloxysilane was rotary evaporated to obtain ionic liquid MI. The molar ratio of the aromatic imidazole intermediate M to the halopropyltriethoxysilane is 1.0:3.1-6.

0.

3. The preparation method according to claim 2, characterized in that, The surfactant is at least one of dimethylethylenediamine, L-proline, or 1,2-cyclohexanediamine; the carbonate is at least one of potassium carbonate, sodium carbonate, or cesium carbonate; and the organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

4. The application of the imidazole ionic liquid for trans-butadiene-pentadiene rubber compounding as described in claim 1, characterized in that, The imidazole ionic liquid for trans-butadiene rubber compounding is used in the wet compounding premixing of trans-butadiene rubber.

5. The application as described in claim 4, characterized in that, The specific steps for wet compounding trans-butadiene rubber are as follows: (1) Mechanical stirring and ultrasonic treatment of natural rubber latex; (2) Dissolve trans-butadiene rubber in an imidazole ionic liquid. After complete dissolution, slowly add it dropwise to an alkaline aqueous solution and stir until a stable trans-butadiene rubber ionic liquid aqueous solution is formed. (3) Slowly add the trans-butadiene rubber ionic liquid aqueous solution to the natural rubber latex; (4) Disperse magnesium hydroxide in distilled water, stir mechanically, and slowly and gradually transfer the well dispersed magnesium hydroxide aqueous solution into natural rubber latex; (5) Heat the natural rubber latex to 40℃-60℃, mechanically stir and ultrasonically premix for 2h-10h. After the premixing is complete, add weak acid to break the emulsion to obtain raw rubber. Wash the raw rubber thoroughly, and then vacuum dry the raw rubber at 20℃-35℃ for 96h-168h to obtain premixed trans-butadiene rubber masterbatch.

6. The application as described in claim 5, characterized in that, In the aforementioned wet mixing process, the raw materials are proportioned in the following mass ratios: 100-200 parts of natural rubber latex; 5-20 parts of trans-butadiene rubber; 10-20 parts of imidazole ionic liquid; 10-20 parts of alkaline aqueous solution; 50-100 parts of magnesium hydroxide; 100-300 parts distilled water; 10-50 parts of weak acid.

7. The application as described in claim 5, characterized in that, The alkaline aqueous solution is an aqueous solution of sodium hydroxide or potassium hydroxide, with a solute-solvent ratio of (1-5) g / 10 mL; the weak acid is oxalic acid and / or acetic acid.

8. The application as described in claim 5, characterized in that, The mechanical stirring speed in step (4) is 500rpm-2000rpm, and the stirring time is 1h-2h.

9. The application as described in any one of claims 4-6, characterized in that, The specific steps for preparing vulcanized rubber using the premixed trans-butadiene rubber obtained by the wet mixing premix are as follows: (1) Mix the premixed trans-butadiene rubber masterbatch evenly at a mixing temperature of 80℃-100℃; (2) Add zinc oxide, stearic acid, antioxidant, carbon black, and silica, and mix at a low temperature for 3-5 minutes; (3) Add sulfur and accelerator, mix for 3-5 minutes, mix at 70℃-90℃, pass through the open mill 3-5 times or make triangular wraps 3-5 times to obtain two-stage compound rubber. (4) After the compound obtained in step (3) is left to stand for at least 16 hours, vulcanized rubber is prepared according to the vulcanization conditions of vulcanization temperature of 145℃-155℃ and vulcanization time of TC90+(2-5)min.

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