Preparation method and application of high-stability homogeneous neodymium catalyst

Abstract

The present application relates to the technical field of rare earth catalyst, in particular to a preparation method and application of a high-stability homogeneous neodymium catalyst.The neodymium catalyst is composed of four components A, B, C and D, and the molar ratio of each component is A:B:C:D=1:(5-50):(0.5-6):(1-10).The prepared neodymium catalyst utilizes the coordination ability of pyridine ligand, forms steric hindrance, inhibits the association of rare earth neodymium catalyst, and improves the stability of the catalyst.The high-stability homogeneous catalyst can be prepared without adding diene, the viscosity of the catalyst is reduced, the aging time is shortened, and the problems such as the fluctuation of polymerization activity caused by the long preparation time of the catalyst are reduced, and the prepared rare earth butadiene rubber cis structure is adjustable.

Description

Technical fields:

[0001] This invention relates to the field of rare earth catalyst technology, and in particular to a method for preparing and applying a highly stable homogeneous neodymium catalyst. Background technology:

[0002] Rare earth cis-butadiene rubber (RBBR) exhibits a regular chain structure, good linearity, high average molecular weight, and narrow molecular weight distribution. It possesses characteristics such as high strength, flexural resistance, low heat generation, good wet skid resistance, and low rolling resistance, making it a preferred rubber type for developing high-performance and green tires. The rare earth catalysts used in RBBR production include rare earth organic acids, alkyl aluminum, and halogens. Among these, the neodymium rare earth catalytic system shows high activity. The ternary neodymium rare earth catalytic system typically exhibits a heterogeneous state because neodymium reacts with halogens to form neodymium chloride, which is insoluble in organic solvents, resulting in precipitation. Due to the presence of multiple rare earth active centers in the heterogeneous ternary rare earth catalytic system, including those soluble and insoluble in organic solvents, the synthesized RBBR has a wider molecular weight distribution and poorer physical and mechanical properties. In addition, due to the high number of electrons and spatial unsaturation of neodymium ions in compounds, their derivatives are prone to interact with oxygen atoms of adjacent molecules to form oligomers. In particular, in the presence of trace amounts of water, it is easier to form oligomers with higher molecular weights. Intermolecular association can also lead to the formation of multiple active sites. At the same time, the higher molecular weight of oligomers will result in higher catalyst viscosity, low utilization of active sites, difficulty in preparing high-concentration organic acids, and a tendency for the polymerization process to become more complex and uncontrollable.

[0003] Existing methods for preparing neodymium catalytic systems typically involve adding a diene to form a complex, thus avoiding heterogeneous conditions. Since the binding of the diene to the active neodymium metal center requires a certain reaction time, precise control of aging conditions such as temperature and time is usually necessary to prepare a homogeneous catalyst with good activity while preventing the formation of diene oligomers. The aging process significantly impacts the activity of the polymerization reaction and the product's structural properties, making process control difficult and prone to causing production fluctuations.

[0004] In addition, adding carboxylic acids and phosphorus-containing compounds to the neodymium catalytic system can form a quaternary rare earth catalytic system, which can inhibit the formation of neodymium oligomers, promote and enhance the catalytic effect of the catalytic system, improve the phase stability of the catalyst, and improve the stereoselectivity of the catalyst. Kwag et al. (Macromolecules, 2002, 35(13): 4875-9.) introduced the preparation of neodymium neodecanoate coordinated with carboxylic acid under anhydrous conditions by adding excess carboxylic acid, avoiding the situation where water occupies the neodymium central orbital as a ligand and thus induces the formation of oligomers. The activity of this single-center neodymium neodecanoate is higher than that of the original neodymium neodecanoate salt. Anwander et al. (Organometallics, 2002, 21(22): 4569-71.) added sterically hindered anions to phosphate ester neodymium salt to inhibit the formation of oligomers. Liao Yuzhen et al. (Applied Chemistry, 1987, 4(1): 13-7.) found that the oligomerization of lanthanide salts in solution can be suppressed by using sterically hindered and rigid phosphate anions. Additionally, adding a small amount of Me₂SiCl₂ to neodymium phosphate esters can also break their association in solution, preparing solution-type neodymium phosphate esters. However, chlorosilanes are less reactive than chloroalkylaluminum, and their effect on the cis content of polybutadiene is minimal. However, the effects of the above methods on the preparation of homogeneous catalytic systems or aging processes have not been reported. Summary of the Invention:

[0005] The technical problem this invention aims to solve is to provide a method for preparing a highly stable homogeneous Nd:dpole catalyst and its application. This Nd:dpole catalyst utilizes the coordination ability of pyridine ligands to form steric hindrance, suppressing the association of rare earth Nd:dpole catalysts and improving catalyst stability. It can prepare a highly stable homogeneous catalyst without adding dienes, reducing catalyst viscosity, shortening aging time, and mitigating problems such as polymerization activity fluctuations caused by excessively long catalyst preparation times. The prepared rare earth cis-butadiene rubber has an adjustable cis structure. This overcomes the shortcomings of existing Nd:dpole catalysts, which require the addition of dienes to avoid heterogeneity, have high catalyst viscosity, long aging times, and polymerization activity fluctuations caused by excessively long catalyst preparation times.

[0006] The technical solution adopted in this invention is: a method for preparing a highly stable homogeneous neodymium catalyst, wherein the neodymium catalyst is composed of four components A, B, C and D, and the molar ratio of each component is A:B:C:D = 1:(5~50):(0.5~6):(1~10);

[0007] A is one or a mixture of several of the following rare earth neodymium organic compounds: rare earth neodymium carboxylate, rare earth neodymium acid phosphate, and rare earth neodymium acid phosphonate.

[0008] B is one or a mixture of several of the following: trialkylaluminum and hydrogenated alkylaluminum.

[0009] C is one or a mixture of several of the following chlorides: diisobutylaluminum chloride, diethylaluminum chloride, sesquiethylaluminum chloride, tert-butyl chloride, benzyl chloride, allyl chloride, silicon tetrachloride, and chloromethylsilane.

[0010] D is one or a mixture of several of the following pyridine compounds: pyridine, pyridine 2,6-dicarboxylic acid, diaminopyridine, diphenylpyridine, and bipyridine.

[0011] The neodymium catalyst is prepared as follows: Under nitrogen protection, A, D, and B are added to a dry catalyst aging reactor according to the ratio. After aging for 0-3 minutes, C is added and aged for 0-3 minutes. Then, the reactor is shaken at 30-80°C for 1 minute to obtain the neodymium catalyst of this product.

[0012] The A is preferably one or a mixture of several of the following: neodymium di(2-ethylhexyl) phosphate, neodymium mono-2-ethylhexyl phosphonate, neodymium naphthenate, neodymium neodecanoate, and neodymium isooctanoate.

[0013] The D is preferably one or a mixture of pyridine, pyridine 2,6-dicarboxylic acid, diaminopyridine, and bipyridine.

[0014] An application of a highly stable homogeneous neodymium catalyst in the preparation of rare earth cis-butadiene rubber is disclosed. The application method comprises the following steps: Under nitrogen protection, an organic solvent and butadiene monomer are added to a dried and deoxygenated polymerization reactor according to a specified ratio. The organic solvent is selected from one of the following saturated alkanes: hexane, cyclohexane, and hydrogenated gasoline. Then, the neodymium catalyst is added, with a molar ratio of neodymium catalyst to butadiene monomer of (8 × 10⁻⁶). -5 ~1.0×10 -3 ): 1. The butadiene monomer concentration is 8-20 g / 100 mL, and the reaction is carried out at 0℃-60℃ for 60 minutes to 6 hours; the reaction is terminated with an ethanol solution containing 1% by mass of 2,6-di-tert-butyl-p-methylphenol, and the polymer is condensed with excess hot water and then dried under vacuum to obtain rare earth cis-butadiene rubber.

[0015] The beneficial effects of this invention are: This invention realizes the use of the coordination ability of pyridine ligands to form steric hindrance, suppress the association of rare earth neodymium catalysts, improve catalyst stability, prepare highly stable homogeneous catalysts without adding dienes, reduce catalyst viscosity, shorten aging time, and reduce problems such as polymerization activity fluctuations caused by excessively long catalyst preparation time. The cis structure of the prepared rare earth cis-butadiene rubber is tunable. Detailed implementation method:

[0016] Comparative Example 1

[0017] Neodymium catalyst preparation process: At room temperature, 20 mL of n-hexane, 0.848 g of Nd(P5O7)3 (0.8 mmol), a hexane solution containing 0.53 g (1.2 mmol) of butadiene, and 14.4 mL of Al(i-Bu)2H (1.0 mol / L) were added sequentially to a 100 mL catalyst aging bottle. The mixture was then reacted at 30 °C for 20 minutes. After that, 4 mL of LAIEt2Cl (1.0 mol / L) was added and the mixture was reacted for another 20 minutes to obtain a homogeneous brownish-red rare earth catalyst.

[0018] Preparation process of rare earth cis-butadiene rubber: 2500 mL of butadiene-hexane solution (monomer concentration of 0.10 g / mL) was added to a 5000 mL polymerization reactor, followed by the addition of 10 mL of the neodymium catalyst prepared above (Nd / butadiene molar ratio of 0.9 × 10⁻⁶). -4 The mixture was stirred and reacted at 70°C for 4 hours. After the reaction was completed, the rubber solution was transferred from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, rare earth cis-butadiene rubber was obtained.

[0019] Structural analysis results of rare earth butadiene rubber products: cis-1,4-polybutadiene content is 97% by mass, trans-1,4-polybutadiene content is 2% by mass, 1,2-polybutadiene content is 1% by mass, and the weight-average molecular weight is 52 × 10⁻⁶. 4 The molecular weight distribution is 2.13, and Mooney (ML1+4at100℃) is 45MU.

[0020] Comparative Example 2

[0021] Unlike Comparative Example 1, no diene was added, resulting in a heterogeneous rare earth catalyst.

[0022] Structural analysis results of rare earth butadiene rubber products: cis-1,4-polybutadiene content is 95% by mass, trans-1,4-polybutadiene content is 4% by mass, and 1,2-polybutadiene content is 1% by mass; weight-average molecular weight is 57 × 10⁻⁶. 4 The molecular weight distribution is 3.23; Mooney (ML1+4at100℃.): 55MU.

[0023] Example 1

[0024] Neodymium catalyst preparation process: At room temperature, 20 mL of n-hexane, 0.848 g of Nd(P5O7)3 (0.8 mmol), 0.06 g of bipyridine (0.8 mmol), and 14.4 mL of Al(i-Bu)2H (1.0 mol / L) were added sequentially to a 100 mL catalyst aging bottle. Then, 4 mL of AlEt2Cl (1.0 mol / L) was added and the reaction was carried out for 1 minute to obtain a homogeneous red rare earth catalyst.

[0025] Preparation process of rare earth cis-butadiene rubber: 2500 mL of butadiene-hexane solution (monomer concentration of 0.10 g / mL) was added to a 5000 mL polymerization reactor, followed by the addition of 10 mL of the neodymium catalyst prepared above (Nd / butadiene molar ratio of 0.9 × 10⁻⁶). -4 The mixture was stirred and reacted at 40°C for 4 hours. After the reaction was completed, the rubber solution was transferred from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, rare earth cis-butadiene rubber was obtained.

[0026] Product structure analysis results: cis-1,4-polybutadiene content is 96% by mass, trans-1,4-polybutadiene content is 3% by mass, 1,2-polybutadiene content is 1% by mass, and the weight-average molecular weight is 42 × 10⁻⁶. 4 The molecular weight distribution is 2.23, Mooney (ML1+4at100℃): 41MU.

[0027] Example 2

[0028] Unlike Example 1, the molar ratio of the components is A:B:C:D = 1:35:3:4.5, and the Nd / butadiene molar ratio is 8 × 10⁻⁶. -5 .

[0029] Product structure analysis results: cis-1,4-polybutadiene content was 94% by mass, trans-1,4-polybutadiene content was 5% by mass, and 1,2-polybutadiene content was 1% by mass; weight-average molecular weight was 29 × 10⁻⁶. 4 The molecular weight distribution is 3.53; Mooney (ML1+4at100℃): 31MU.

[0030] Example 3

[0031] Unlike Example 1, the added pyridine compound was diaminopyridine. The molar ratio of each component was A:B:C:D = 1:5:0.5:1, and the Nd / butadiene molar ratio was 3 × 10⁻⁶. -4 .

[0032] Product structure analysis results: cis-1,4-polybutadiene content is 99% by mass, trans-1,4-polybutadiene content is 0.5% by mass, and 1,2-polybutadiene content is 0.5% by mass; weight-average molecular weight is 45 × 10⁻⁶. 4 The molecular weight distribution is 2.45; Mooney (ML1+4at100℃): 58MU.

[0033] Example 4

[0034] Unlike Example 1, the added pyridine compound was diaminopyridine. The molar ratio of each component was A:B:C:D = 1:23:4:9, and the Nd / butadiene molar ratio was 1.0 × 10⁻⁶. -3 The butadiene monomer concentration is 17g / 100mL.

[0035] Product structure analysis results: cis-1,4-polybutadiene content was 94% by mass, trans-1,4-polybutadiene content was 3% by mass, and 1,2-polybutadiene content was 1% by mass; weight-average molecular weight was 42 × 10⁻⁶. 4 The molecular weight distribution is 2.75; Mooney (ML1+4at100℃): 48MU.

[0036] Example 5

[0037] Unlike Example 1, the added pyridine compound was diphenylpyridine, and the molar ratio between the components was A:B:C:D = 1:11:2:3, with an Nd / butadiene molar ratio of 6 × 10⁻⁶. -4 The butadiene monomer concentration is 8 g / 100 mL.

[0038] Product structure analysis results: cis-1,4-polybutadiene content is 95% by mass, trans-1,4-polybutadiene content is 3% by mass, and 1,2-polybutadiene content is 2% by mass; weight-average molecular weight is 40 × 10⁻⁶. 4 The molecular weight distribution is 2.51; Mooney (ML1+4at100℃): 46MU.

[0039] Example 6

[0040] Unlike Example 1, the added pyridine compound was diphenylpyridine, and the molar ratio between the components was A:B:C:D = 1:30:0.8:8, with an Nd / butadiene molar ratio of 3.2 × 10⁻⁶. -4 The butadiene monomer concentration is 20g / 100mL.

[0041] Product structure analysis results: cis-1,4-polybutadiene content was 98% by mass, trans-1,4-polybutadiene content was 1% by mass, and 1,2-polybutadiene content was 1% by mass; weight-average molecular weight was 31 × 10⁻⁶. 4 The molecular weight distribution is 3.32; Mooney (ML1+4at100℃): 41MU.

[0042] Example 7

[0043] Unlike Example 1, the neodymium compound used was neodymium isooctanoate, and the molar ratio between the components was A:B:C:D = 1:24:2.5:2.5, with an Nd / butadiene molar ratio of 4.7 × 10⁻⁶. -4 The butadiene monomer concentration is 15g / 100mL.

[0044] Product structure analysis results: cis-1,4-polybutadiene content is 97% by mass, trans-1,4-polybutadiene content is 2% by mass, and 1,2-polybutadiene content is 1% by mass; weight-average molecular weight is 42 × 10⁻⁶. 4 The molecular weight distribution is 2.91; Mooney (ML1+4at100℃): 43U.

[0045] Example 8

[0046] Unlike Example 1, the neodymium compound used was neodymium isooctanoate, and the molar ratio between the components was A:B:C:D = 1:31:6:5, with an Nd / butadiene molar ratio of 5 × 10⁻⁶. -4 The butadiene monomer concentration is 12g / 100mL.

[0047] Product structure analysis results: cis-1,4-polybutadiene content is 95% by mass, trans-1,4-polybutadiene content is 4% by mass, and 1,2-polybutadiene content is 1% by mass; weight-average molecular weight is 35 × 10⁻⁶. 4 The molecular weight distribution is 2.41; Mooney (ML1+4at100℃): 41MU.

[0048] Example 9

[0049] Unlike Example 1, the neodymium compound used was neodymium naphthenate, and the molar ratio between the components was A:B:C:D = 1:11:4:10.

[0050] Product structure analysis results: cis-1,4-polybutadiene content was 98% by mass, trans-1,4-polybutadiene content was 1% by mass, and 1,2-polybutadiene content was 1% by mass; weight-average molecular weight was 53 × 10⁻⁶. 4 The molecular weight distribution is 2.74; Mooney (ML1+4at100℃): 58MU.

[0051] Example 10

[0052] Unlike Example 1, the added pyridine compound was a mixture of pyridine 2-6 dicarboxylate and pyridine. The molar ratio between the components was A:B:C:D = 1:12:3:(1+3.5).

[0053] Product structure analysis results: cis-1,4-polybutadiene content was 94% by mass, trans-1,4-polybutadiene content was 4% by mass, and 1,2-polybutadiene content was 2% by mass; weight-average molecular weight was 42 × 10⁻⁶. 4 The molecular weight distribution is 2.317; Mooney (ML1+4at100℃): 48MU.

[0054] Example 11

[0055] Unlike Example 1, the components were added sequentially in the order of A, D, B, and C.

[0056] Product structure analysis results: cis-1,4-polybutadiene content is 97% by mass, trans-1,4-polybutadiene content is 2% by mass, and 1,2-polybutadiene content is 1% by mass; weight-average molecular weight is 52 × 10⁻⁶. 4 The molecular weight distribution is 2.26; Mooney (ML1+4at100℃): 45MU.

[0057] Example 12

[0058] Unlike Example 1, the components were added sequentially in the order of D, A, B, and C.

[0059] Product structure analysis results: cis-1,4-polybutadiene content was 97% by mass, trans-1,4-polybutadiene content was 2% by mass, and 1,2-polybutadiene content was 1% by mass; weight-average molecular weight was 51 × 10⁻⁶. 4 The molecular weight distribution is 2.45; Mooney (ML1+4at100℃): 47MU.

[0060] Example 13

[0061] Unlike Example 1, the molar ratio of each component is: A:B:C:D = 1:50:0.5:7.

[0062] Product structure analysis results: cis-1,4-polybutadiene content was 93% by mass, trans-1,4-polybutadiene content was 5% by mass, and 1,2-polybutadiene content was 2% by mass; weight-average molecular weight was 57 × 10⁻⁶. 4 The molecular weight distribution is 2.44; Mooney (ML1+4at100℃): 62MU.

[0063] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A process for the preparation of a highly stable homogeneous neodymium catalyst, characterized in that: The neodymium catalyst is composed of four components A, B, C and D, and the molar ratio of each component is A:B:C:D=1:(5-50):(0.5-6):(1-10); The A is one or a mixture of several of the rare earth neodymium carboxylate, rare earth neodymium acid phosphate, and rare earth acid phosphonic acid neodymium in the rare earth neodymium organic compound; The B is one or a mixture of several of the trialkylaluminum and hydrogenated alkylaluminum in the alkylaluminum; The C is one or a mixture of several of the dichlorodiisobutylaluminum, dichlorodiethylaluminum, sesquiethylaluminum, tert-butyl chloride, benzyl chloride, allyl chloride, silicon tetrachloride, and chloromethylsilane in the chlorides; The D is one or a mixture of several of the 2,6-diformylpyridine, diaminopyridine, diphenylpyridine, and bipyridine in the pyridine compounds; The preparation method of the neodymium catalyst is as follows: under the protection of nitrogen, A, D and B are added to a dry catalyst aging reactor according to the ratio, aged for 0-3 min, then C is added, aged for 0-3 min, then oscillated at 30-80℃ for 1 min to obtain the product neodymium catalyst.

2. The process for the preparation of a highly stable homogeneous neodymium catalyst according to claim 1, characterized in that: The A is one or a mixture of several of the neodymium di(2-ethylhexyl)phosphate, 2-ethylhexyl phosphonic acid neodymium mono 2-ethylhexyl ester, neodecanoic acid neodymium, and isooctanoic acid neodymium.

3. Use of a high-stability homogeneous neodymium catalyst prepared according to the preparation method of claim 1, characterized in that: The neodymium catalyst is applied in the preparation of rare earth butadiene rubber, and the application method comprises the following steps: under the protection of nitrogen, an organic solvent and butadiene monomer are added into a dry and oxygen-free polymerization reactor according to a proportion, the organic solvent is selected from one of saturated alkanes, hexane, cyclohexane and hydrogenated gasoline, then the neodymium catalyst is added, the molar ratio of the neodymium catalyst to the butadiene monomer is (8*10 -5 ~1.0*10 -3 ):1, the concentration of the butadiene monomer is 8-20 g / 100 mL, and the reaction is carried out at 0-60 DEG C for 60 minutes to 6 hours; the reaction is terminated by using an ethanol solution containing 1% of 2,6-di-tert-butyl-p-cresol in mass percentage, the polymer is coagulated by using excessive hot water, and then vacuum drying is carried out to obtain the rare earth butadiene rubber.