Iron-based poly-conjugated diene rubber as well as preparation method and application thereof

Abstract

The invention relates to the field of conjugated diene polymerization, and discloses iron-based poly conjugated diene rubber as well as a preparation method and application thereof. The method comprises the following steps: (1) in a protective atmosphere, in the presence of an organic solvent I, carrying out aging treatment on a bipyridine iron complex, a conjugated diene monomer I and aluminum alkyl to obtain a material I; (2) in the presence of an organic solvent II, carrying out polymerization reaction on the material I and a conjugated diene monomer II to obtain a material II; and (3) mixing the material II with an anti-aging agent and a quenching agent to obtain the iron-based poly-conjugated diene rubber, the conjugated diene monomer I and the conjugated diene monomer II are the same or different in type. The preparation method of the iron-based poly-conjugated diene rubber provided by the invention is simple, complete conversion of the monomer can be realized without using borate in a reaction catalysis system, the production cost is lower, and industrial production is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of conjugated diene polymerization, and in particular to an iron-based polyconjugated diene rubber and a preparation method and application thereof. Background Art

[0002] Rubbers derived from the polymerization of conjugated dienes play an important role in synthetic rubber. Cis-isoprene rubber and butadiene rubber are common rubbers in my country, enjoying a wide range of applications. Research has shown that branched conjugated diene polymers offer significant advantages in wet skid resistance in tire applications, demonstrating broad application prospects.

[0003] Iron-catalyzed systems are important for the preparation of branched conjugated diene polymers due to their low cost and environmental friendliness. In iron-catalyzed conjugated diene polymerizations, borates and MAO are typically used to ensure the stability and reactivity of the catalytic centers. However, the polymerization process for these catalytic systems is relatively complex, and the inclusion of borates leads to high production costs. Furthermore, these systems are limited to laboratory research, hindering their application in industrial production.

[0004] CN114249849A discloses a kind of preparation method of iron-based conjugated diene polymer, and the method includes: under argon atmosphere, bipyridine iron complex and modified aluminum catalyst system, conjugated diene monomer and solvent are added into reactor to form reaction system, and polyreaction is carried out 10min~30min at 0 ℃~90 ℃ with stirring, and quencher and anti-aging agent are added after reaction is completed, washing, drying, obtain iron-based conjugated diene polymer.Compared with prior art, the method avoids the use of necessary dealkylating agent in alkyl aluminum system, reduces process flow, reduces reaction cost, provides important technical support for the industrialized production of iron-based rubber, and simultaneously, the conjugated diene polymer obtained has the characteristics of high branching, low gel content or even no gel and low glass transition temperature, significantly improves product quality and performance.However, there is intense heat release in the process of preparing modified aluminum in the method, increases the safety risk in production process, and the aluminum agent consumption is larger, and production cost increases.

[0005] Therefore, in view of the low production cost, simple process and high catalytic activity pursued in industrial production, a preparation method of iron-based branched conjugated diene rubber suitable for factory reaction equipment was developed. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing an iron-based polyconjugated diene rubber with high yield and low production cost.

[0007] During their research, the inventors discovered that when conjugated diene monomers are aged at low temperatures to form active chains before polymerization, the aged catalyst system becomes more stable and more active, facilitating complete monomer conversion. Furthermore, this catalyst system can form catalytically active centers without the need for borate or modifiers, resulting in a simple reaction system and lower polymerization costs.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for preparing an iron-based polyconjugated diene rubber, the method comprising:

[0009] (1) Under a protective atmosphere, in the presence of an organic solvent I, a bipyridine iron complex, a conjugated diene monomer I, and an alkyl aluminum are subjected to an aging treatment to obtain a material I;

[0010] The aging treatment conditions include: temperature of -30°C to -10°C, time of 30-120 minutes;

[0011] (2) in the presence of an organic solvent II, polymerizing the material I with a conjugated diene monomer II to obtain a material II;

[0012] (3) mixing the material II with an antioxidant and a quencher to obtain an iron-based polyconjugated diene rubber;

[0013] The molar ratio of the conjugated diene monomer II to the bipyridine iron complex calculated as iron element is 7000-16000:1;

[0014] The conjugated diene monomer I and the conjugated diene monomer II are of the same or different types.

[0015] The second aspect of the present invention provides an iron-based polyconjugated diene rubber prepared by the method described in the first aspect.

[0016] The third aspect of the present invention provides use of the iron-based polyconjugated diene rubber described in the second aspect in rubber products.

[0017] The preparation method of the iron-based polyconjugated diene rubber provided by the present invention is simple, and complete monomer conversion can be achieved without the use of borate in the reaction catalytic system. This method reduces production costs and facilitates industrial production. Furthermore, the prepared iron-based polyconjugated diene rubber has a number-average molecular weight of 280,000 to 550,000, and the molar content of 3,4-structures in polyisoprene and 1,2-structures in polybutadiene is greater than or equal to 60%, demonstrating high branching. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The iron-based polyconjugated diene rubber (polyisoprene) obtained in Example 1 1 H NMR spectrum. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] As mentioned above, the first aspect of the present invention provides a method for preparing an iron-based polyconjugated diene rubber, the method comprising:

[0021] (1) Under a protective atmosphere, in the presence of an organic solvent I, a bipyridine iron complex, a conjugated diene monomer I, and an alkyl aluminum are subjected to an aging treatment to obtain a material I;

[0022] The aging treatment conditions include: temperature of -30°C to -10°C, time of 30-120 minutes;

[0023] (2) in the presence of an organic solvent II, polymerizing the material I with a conjugated diene monomer II to obtain a material II;

[0024] (3) mixing the material II with an antioxidant and a quencher to obtain an iron-based polyconjugated diene rubber;

[0025] The molar ratio of the conjugated diene monomer II to the bipyridine iron complex calculated as iron element is 7000-16000:1;

[0026] The conjugated diene monomer I and the conjugated diene monomer II are of the same or different types.

[0027] Preferably, the protective atmosphere is provided by nitrogen or helium.

[0028] Preferably, the bipyridine iron complex is selected from at least one of the following structures:

[0029]

[0030] During the research, the inventors found that in the preferred case, the bipyridine iron complex combined with alkyl aluminum as the catalyst system has higher catalytic activity and is more conducive to the formation of iron-based conjugated diene rubber.

[0031] Preferably, in step (1), the molar ratio of the conjugated diene monomer I to the bipyridine iron complex calculated as iron element is 10-500:1; preferably 100-500:1.

[0032] Preferably, the bipyridine iron complex is provided by a hexane solution of the bipyridine iron complex.

[0033] Preferably, the concentration of the bipyridyl iron complex in the hexane solution is 0.001-0.1 mol / L. More preferably, the concentration of the bipyridyl iron complex in the hexane solution is 0.03-0.07 mol / L.

[0034] Preferably, in step (1), the molar ratio of the alkyl aluminum calculated as aluminum element to the bipyridine iron complex calculated as iron element is 10-100:1.

[0035] Preferably, in step (1), the amount of the organic solvent I is 0.4-1.2 mL relative to 1 mmol of the conjugated diene monomer I.

[0036] Preferably, the conjugated diene monomer I and the conjugated diene monomer II are each independently selected from at least one of butadiene and isoprene.

[0037] Preferably, the alkyl aluminum is at least one of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

[0038] More preferably, the alkyl aluminum is triisobutyl aluminum. The inventors have found that in this preferred embodiment, the catalyst system formed by triisobutyl aluminum and bipyridine iron complex has higher activity and the obtained iron-based polyconjugated diene rubber has a higher degree of branching.

[0039] The present invention has no particular requirements for the apparatus used for the aging treatment, and those skilled in the art may select one as needed. For example, the aging treatment is performed in a catalyst aging treatment apparatus comprising an alkyl aluminum tank, a monomer tank, a solvent tank, a catalyst aging tank, and a bipyridine iron complex solution tank equipped with a mechanical stirrer and a delivery pump.

[0040] Preferably, the organic solvent I and the organic solvent II are each independently selected from at least one of toluene, p-xylene, n-hexane, cyclohexane, petroleum ether, pentane, and hydrogenated gasoline.

[0041] Preferably, in step (2), the amount of the organic solvent II is 0.8-1.2 mL relative to 1 mmol of the conjugated diene monomer II.

[0042] Preferably, the molar ratio of the conjugated diene monomer II to the bipyridine iron complex calculated as iron element is 8000-15000:1.

[0043] Preferably, in step (2), the polymerization reaction conditions include: temperature of 20-60° C., and time of 10-480 min. More preferably, the polymerization reaction conditions include: temperature of 20-40° C., and time of 100-180 min.

[0044] Preferably, in step (3), the mixing conditions include: temperature of 20-30° C. and time of 100-130 min.

[0045] According to a preferred embodiment, in step (3), the anti-aging agent is an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a concentration of 0.5-1.5 wt%.

[0046] According to another preferred embodiment, the volume ratio of the antioxidant to the organic solvent II is 1:40-60.

[0047] Preferably, the quenching agent is a mixed solution of concentrated hydrochloric acid and methanol, and the volume ratio of the methanol to concentrated hydrochloric acid is 40-50:1.

[0048] Preferably, the concentrated hydrochloric acid is hydrochloric acid with a mass fraction of 30-37 wt%.

[0049] Preferably, the volume ratio of the quencher to the organic solvent II is 1:180-220.

[0050] Preferably, the method further comprises: washing and drying the mixed materials in sequence to obtain the iron-based polyconjugated diene rubber.

[0051] The present invention does not particularly limit the washing and drying methods, and those skilled in the art can perform them according to known technical means. For example, the mixed material is washed three times with anhydrous ethanol and then dried at 40° C. to a constant weight to obtain the iron-based polyconjugated diene rubber.

[0052] The aging treatment, the polymerization reaction, and the mixing in the present invention are preferably carried out under stirring conditions. The present invention does not particularly limit the stirring speed, and those skilled in the art can select it as needed.

[0053] As mentioned above, the second aspect of the present invention provides an iron-based polyconjugated diene rubber prepared by the method described in the first aspect.

[0054] Preferably, the iron-based polyconjugated diene rubber has a number average molecular weight of 280,000-550,000, a molecular weight distribution index of 2.0-4.0, and a branching degree of ≥60%.

[0055] As mentioned above, the third aspect of the present invention provides the use of the iron-based polyconjugated diene rubber described in the second aspect in rubber products.

[0056] The present invention is described in detail below using examples. Unless otherwise specified, the instruments, reagents, and materials used in the following examples are all conventional instruments, reagents, and materials available in the prior art and can be obtained through regular commercial channels. The experimental methods and detection methods used in the following examples are all conventional experimental methods and detection methods available in the prior art, unless otherwise specified.

[0057] Antiaging agent I: 1 g of 2,6-di-tert-butyl-4-methylphenol was dissolved in 99 g of ethanol solution to prepare a 1 wt% 2,6-di-tert-butyl-4-methylphenol ethanol solution.

[0058] Quenching agent I: obtained by mixing methanol and concentrated hydrochloric acid (mass fraction 37 wt%) in a volume ratio of 50:1.

[0059] Bipyridine iron complex I, bipyridine iron complex II, and bipyridine iron complex DI are represented by formula (I), formula (II), and formula (DI), respectively; the specific structures are as follows:

[0060]

[0061] Bipyridine iron complex I, bipyridine iron complex II, and bipyridine iron complex DI were prepared according to Examples 5, 6, and 9 in CN114249849A; and the prepared bipyridine iron complex I, bipyridine iron complex II, and bipyridine iron complex DI were respectively prepared using hexane to prepare 0.05 mol / L bipyridine iron complex hexane solutions, which were named iron complex solution A, iron complex solution B, and iron complex solution C, respectively.

[0062] Example 1

[0063] In this embodiment, the iron-based polyconjugated diene rubber is prepared according to the formula and process parameters in Table 1 and the following method. The preparation method of the iron-based polyconjugated diene rubber includes the following steps:

[0064] (1) In a nitrogen atmosphere, an organic solvent I, a hexane solution of a bipyridine iron complex, a conjugated diene monomer I, and an alkyl aluminum were sequentially added to a catalyst aging tank and aged at 150 rpm to obtain a material I;

[0065] The aging treatment conditions are: temperature of -10°C and time of 60 min;

[0066] (2) In a 5 L polymerization reactor, the material I, the organic solvent II, and the conjugated diene monomer II were polymerized at 150 rpm to obtain a material II;

[0067] The polymerization reaction conditions are: temperature 30°C, time 120 min;

[0068] (3) mixing the material II with an antioxidant and a quencher at 150 rpm. After the reaction is terminated, the mixed material is washed three times with anhydrous ethanol and then dried at 40° C. to a constant weight to obtain an iron-based polyconjugated diene rubber;

[0069] The mixing conditions are: temperature of 30° C. and time of 120 min.

[0070] The product obtained in Example 1 was 1 H NMR characterization analysis, the results are as follows Figure 1 shown.

[0071] Unless otherwise specified, the remaining examples were carried out using a process similar to that of Example 1, except that the raw materials and amounts used, and the process parameters were different. For details, see Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Table 1

[0076]

[0077] Comparative Example 1

[0078] This comparative example was carried out using a method similar to that of Example 1, except that no aging treatment was performed in this comparative example. The specific operation was as follows: Under a nitrogen atmosphere, organic solvent I, a hexane solution of a bipyridine iron complex, conjugated diene monomer I, alkyl aluminum, organic solvent II, and conjugated diene monomer II were sequentially added into a 5 L polymerization reactor and polymerization reaction was carried out at 150 rpm to obtain material II;

[0079] The polymerization reaction conditions are: temperature 30°C, time 120 min;

[0080] The remaining steps are the same as those in Example 1.

[0081] Comparative Example 2

[0082] This comparative example was carried out using a method similar to that of Example 1, except that the aging treatment temperature was 10° C. and the time was 60 min; the remaining steps were the same as those of Example 1.

[0083] Comparative Example 3

[0084] This comparative example was carried out using a method similar to that of Example 1, except that the temperature of the aging treatment was -50°C; the remaining steps were the same as those of Example 1.

[0085] Comparative Example 4

[0086] This comparative example was carried out using a method similar to that of Example 1, except that the amount of isoprene used in step (3) was 5700 mmol; the remaining steps were the same as those of Example 1.

[0087] Comparative Example 5

[0088] This comparative example was carried out using a method similar to that of Example 1, except that the polymerization reaction of step (2) was not carried out in this comparative example. Specifically, the material I obtained in step (1) was mixed with an antioxidant and a quencher to obtain an iron-based polyconjugated diene rubber;

[0089] The remaining steps are the same as those in Example 1.

[0090] Test Case

[0091] The iron-based polyconjugated diene rubber prepared in the above example was tested for performance. The number average molecular weight and molecular weight distribution index (PDI) were determined by gel permeation chromatography (GPC) analysis using an Agilent-1260 instrument. The method involved dissolving 5 mg of the polymer sample in 4 mL of chromatography-grade tetrahydrofuran (THF) and filtering the completely dissolved solution through an organic filter with a pore size of 0.25 μm to obtain the test sample. During the test, the sample was passed through a chromatography column at a flow rate of 1.0 mL / min at 40°C while eluting with chromatography-grade THF. The molecular weight (Mn) and molecular weight distribution (PDI) of the polymer were determined based on the time it took to exit the column.

[0092] The molar contents of 1,4-structure and 1,2-structure in polybutadiene and the molar contents of 1,4-structure and 3,4-structure in polyisoprene were quantitatively determined by nuclear magnetic resonance. The yield was calculated according to the following formula: yield = actual weighed weight of product / theoretical weight of product × 100%. The test results are shown in Table 2.

[0093] Table 2

[0094]

[0095] Calculation of production cost of catalytic polymerization reaction:

[0096] Taking Example 1 of the present invention as an example, the aggregation cost is calculated:

[0097] The molar ratio of bipyridine iron complex to conjugated diene monomer and alkyl aluminum is 1:10000:40; 1.5 kg of bipyridine iron complex and 12 kg of alkyl aluminum are required to produce each ton of iron-based conjugated diene polymer, with the bipyridine iron complex costing 200 yuan per kilogram and the alkyl aluminum costing 80 yuan per kilogram; the total cost of the catalytic system in the production process is 1,260 yuan per ton.

[0098] An iron-based conjugated diene polymer was synthesized according to Example 49 in CN114249849A. The catalytic polymerization cost was:

[0099] The molar ratio of bipyridine iron complex to conjugated diene monomer and alkyl aluminum is 1:5000:40; the production of each ton of iron-based conjugated diene polymer requires 3.0 kg of bipyridine iron complex, 24 kg of organoaluminum compound and 1.5 kg of modifier (water); the bipyridine iron complex costs 200 yuan per kilogram; the organoaluminum compound costs 80 yuan per kilogram; the cost of the catalytic system in the production process is a total of 2,520 yuan.

[0100] From the above comparison, it can be seen that the method provided by the present invention can significantly reduce the cost of the catalytic system in the polymerization reaction, and when the modifier in CN114249849A is an organic compound, its production cost is higher.

[0101] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing an iron-based conjugated diene rubber, characterized in that: The method includes: (1) Under a protective atmosphere, in the presence of an organic solvent I, a bipyridine iron complex, a conjugated diene monomer I, and an alkyl aluminum are subjected to an aging treatment to obtain a material I; The aging treatment conditions include: temperature of -30°C to -10°C, time of 30-120 minutes; (2) in the presence of an organic solvent II, polymerizing the material I with a conjugated diene monomer II to obtain a material II; (3) mixing the material II with an antioxidant and a quencher to obtain an iron-based polyconjugated diene rubber; The molar ratio of the conjugated diene monomer II to the bipyridine iron complex calculated as iron element is 7000-16000:1; The conjugated diene monomer I and the conjugated diene monomer II are of the same or different types.

2. The method according to claim 1, wherein The bipyridine iron complex is selected from at least one of the following structures:

3. The method according to claim 1 or 2, wherein: In step (1), the molar ratio of the conjugated diene monomer I to the bipyridine iron complex calculated as iron element is 10-500:1; preferably 100-500:1; Preferably, in step (1), the molar ratio of the alkyl aluminum calculated as aluminum element to the bipyridine iron complex calculated as iron element is 10-100:

1.

4. The method according to any one of claims 1 to 3, wherein: The conjugated diene monomer I and the conjugated diene monomer II are each independently selected from at least one of butadiene and isoprene; and / or The alkyl aluminum is at least one of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

5. The method according to any one of claims 1 to 4, wherein: The molar ratio of the conjugated diene monomer II to the bipyridine iron complex calculated as iron element is 8000-15000:

1.

6. The method according to any one of claims 1 to 5, wherein: In step (2), the polymerization reaction conditions include: temperature of 20-60° C., time of 10-480 min; Preferably, the polymerization reaction conditions include: temperature of 20-40° C. and time of 100-180 min.

7. The method according to any one of claims 1 to 6, wherein: In step (3), the anti-aging agent is an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a concentration of 0.5-1.5 wt%; and / or The volume ratio of the antioxidant to the organic solvent II is 1:40-60.

8. The method according to any one of claims 1 to 7, wherein: The quenching agent is a mixed solution of concentrated hydrochloric acid and methanol, and the volume ratio of methanol to concentrated hydrochloric acid is 40-50:1; and / or The volume ratio of the quenching agent to the organic solvent II is 1:180-220.

9. Iron-based polyconjugated diene rubber prepared by the method according to any one of claims 1 to 8.

10. Use of the iron-based conjugated diene rubber according to claim 9 in rubber products.

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