Low Mooney viscosity random 1, 2-polybutadiene and preparation method and application thereof

Abstract

The invention belongs to the technical field of preparation of synthetic rubber, and particularly relates to low-Mooney-viscosity random 1, 2-polybutadiene as well as a preparation method and application thereof. The preparation method of the low-Mooney-viscosity random 1, 2-polybutadiene comprises the following steps: adding a phosphate ester compound into a molybdenum compound under protective gas, aging, cooling, and adding toluene to obtain a main catalyst; the method comprises the following steps: carrying out ice-water bath on an alkane solution of trialkylaluminium, dropwise adding an aryloxy ligand into a container, and carrying out ice-water bath reaction to obtain a cocatalyst; the preparation method comprises the following steps: dissolving butadiene in an alkane solution, respectively adding a cocatalyst, a main catalyst, an activating agent and a molecular weight regulator, and carrying out polymerization reaction to obtain the low-Mooney-viscosity random 1, 2-polybutadiene. According to the preparation method of the low-Mooney-viscosity random 1, 2-polybutadiene, provided by the invention, the conversion rate is high; the prepared 1, 2-PB is low in Mooney value and high in 1, 2-structure content; and the performance of the rubber additive and the damping material can be improved when the rubber additive is applied to the damping material.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of synthetic rubber, and in particular relates to low Mooney viscosity random 1,2-polybutadiene and a preparation method and application thereof. Background Art

[0002] High vinyl polybutadiene rubber (1,2-PB) has excellent characteristics such as high anti-slip, low heat generation, low rolling resistance and aging resistance. It is a rubber material used to prepare safe and energy-saving "green" tires. 1,2-PB has a high vinyl content and a large molecular weight. The Mooney viscosity of the product is relatively high (usually greater than 80). During the processing, there are problems such as poor material absorption and poor miscibility with other rubbers. In addition, 1,2-PB has the characteristics of high damping and can be used as a damping material for sound absorption and shock absorption after foaming, but the high viscosity of rubber Mooney will affect the quality of the foam cells and mechanical properties. Low Mooney (20-40) viscosity 1,2-PB can also be used as a rubber additive to improve the processing and mechanical properties of rubber, while improving the solvent extraction performance, anti-slip, aging resistance and damping performance of rubber. Therefore, the development of a low Mooney viscosity 1,2-PB is of great significance for expanding its application in tires and rubber products.

[0003] CN114591454A discloses an olefin metathesis technology. The polymerization catalyst is composed of a main catalyst (a complex of a molybdenum compound and a phosphate or alcohol) and a co-catalyst (a complex of an alkyl aluminum and a phenolic compound). Although the molecular weight of 1,2-PB can be reduced, the metathesis catalyst is expensive. The price of the catalyst per ton of rubber is as high as hundreds of thousands, which is difficult to produce industrially. At present, adjusting the molecular weight and distribution of 1,2-PB is the main method to reduce the Mooney viscosity of 1,2-PB. Molybdenum-based catalysts are commonly used catalytic systems for catalytic synthesis of random 1,2-PB. They not only have the advantages of high activity, but also have a 1,2-structure content of up to 80%. EP0483572A1 discloses a catalytic system composed of a molybdenum compound substituted with an alkyl acid of 10 to 30 carbon atoms or an aromatic carboxylic acid of 7 to 30 carbon atoms and an alkyl-substituted phenol or an allyl-substituted phenol to prepare 1,2-PB with a molecular weight of 250,000, but the molecular weight is still high, and the Mooney viscosity is greater than 60.

[0004] US4912182A discloses that the molecular weight of high vinyl polybutadiene can be reduced to within the required range for industrial application by using allylphenol as an additive to modify trialkylaluminum compounds. However, the product prepared by this catalytic system is syndiotactic 1,2-PB with a melting point of 195 to 215°C, which is suitable for use as plastics but difficult to be applied to rubber.

[0005] CN104530282A discloses a method for preparing random 1,2-polybutadiene, using butadiene as a monomer and a catalyst comprising the following components: a) an organic iron phosphate compound solution; b) an alkyl aluminum and / or a hydrogenated alkyl aluminum; c) an electron donor, wherein the electron donor is a phosphorus-containing organic compound and / or a nitrogen-containing organic compound and / or an oxygen-containing organic compound. Although the conversion rate is improved, the 1,2-structure content is low.

[0006] Tang Xueming (Wang Guangxin, Xu Ling, Ma Wenhua, Yang Yuwei, Tang Xueming, Effect of Allyl Halide on the Kinetics of Butadiene Polymerization Catalyzed by Mo(Ⅳ) System, Synthetic Rubber Industry, 1988, 11(5): 380-384) studied the effects of more than 20 polar additives on the polymerization system. The results showed that in the molybdenum catalytic system, the double bond on the allyl halide has a similar electronegativity to butadiene, chain transfer can occur, and there is an excellent molecular weight regulation effect. The molecular weight can be reduced to below 200,000, and the Mooney viscosity can be reduced to below 40. The molecular weight regulation ability of allyl halide is: allyl bromide > allyl iodide > allyl chloride. After allyl iodine and allyl chloride are added to the catalytic system, iodine and chlorine have a retarding effect, which reduces the conversion rate of the system. Although allyl bromide can be used to prepare 1,2-PB with a Mooney viscosity lower than 40 without affecting its activity, the boiling point of allyl bromide is 70°C, which is very close to the boiling point of solvent oil n-hexane, 69°C. It is very difficult to remove it later, which affects the recycling of solvent oil and is not conducive to industrial production. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing low-Mooney viscosity random 1,2-polybutadiene, which has high conversion rate and high solvent recovery rate; the prepared 1,2-PB has a Mooney value of 20-40 and a high 1,2-structure content; and the method is applied to rubber additives and damping materials to improve their mechanical properties and processing properties.

[0008] The method for preparing low Mooney viscosity random 1,2-polybutadiene of the present invention comprises the following steps:

[0009] S1. Preparation of main catalyst

[0010] Under protective gas, add a phosphate compound to the molybdenum compound, age at 70-80° C. for 30-60 minutes, cool to room temperature, and dilute to obtain a main catalyst;

[0011] The molybdenum compound is a pentavalent molybdenum compound, and more preferably molybdenum pentachloride.

[0012] S2. Preparation of co-catalyst

[0013] Under protective gas, immerse the alkane solution of trialkylaluminum in an ice water bath at 0-5°C, add aromatic oxygen ligand dropwise into the container, control the pressure not to exceed 0.2MPa, and react in an ice water bath for 4-8h after the addition is completed to obtain a co-catalyst.

[0014] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0015] Butadiene CH2=CH-CH=CH2 (Bd) is dissolved in a solvent, and a co-catalyst, a main catalyst, an activator and a molecular weight regulator are added respectively, and polymerization is carried out at 50-80°C for 240-360 minutes to obtain low Mooney viscosity random 1,2-polybutadiene.

[0016] The diluent used in S1 is toluene or xylene, and the toluene or xylene is a solvent treated by sodium wire reflux, and its function is to remove water in the solvent and improve the conversion rate.

[0017] The phosphate compound in S1 is triethyl phosphate or tripropyl phosphate, and the molar ratio of the phosphate compound to the molybdenum compound is 2-5.

[0018] The trialkylaluminum in S2 is triethylaluminum, tributylaluminum or tripropylaluminum.

[0019] The dropping speed in S2 is preferably 1 drop / second.

[0020] The aryloxy ligand in S2 is 3-methylphenol; the molar ratio of the aryloxy ligand to the trialkylaluminum is 0.8 to 1.2, and more preferably 1.

[0021] The alkane solution of trialkylaluminum in S2 is preferably a n-hexane solution of trialkylaluminum.

[0022] The solvent in S3 is hydrogenated gasoline or n-hexane or cyclohexane, preferably n-hexane.

[0023] The amount of the main catalyst added in S3 is calculated as molybdenum (Mo), and the molar ratio of the main catalyst to butadiene is 1.5×10 -4 ~3×10 -4 The amount of the co-catalyst added is calculated as aluminum (Al), and the molar ratio of the co-catalyst to the main catalyst is 8 to 16.

[0024] The activator in S3 is 1-methylnaphthalene, 1-ethylnaphthalene or 1-propylnaphthalene, and the volume ratio of the activator to the solvent is 0.1 to 0.17.

[0025] The molecular weight regulator in S3 is 3-bromo-2-methylpropene or trans-1-bromo-2-butene or a mixture of the two, and the amount added is calculated based on bromine, and the molar ratio of the molecular weight regulator to the main catalyst is 3 to 10. The molecular weight regulator is preferably added by first dissolving the molecular weight regulator in n-hexane to a concentration of 0.017 mol / mL.

[0026] A low Mooney viscosity random 1,2-polybutadiene is prepared by the preparation method of the low Mooney viscosity random 1,2-polybutadiene.

[0027] Application of a low Mooney viscosity random 1,2-polybutadiene: used in rubber additives and damping materials to improve their processing performance and mechanical properties.

[0028] Specifically, the method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0029] S1. Preparation of main catalyst

[0030] Under nitrogen protection, a pentavalent molybdenum compound is added to a configuration container, and a phosphate compound is added, the molar ratio of the phosphate compound to the molybdenum compound is 2-5, and the mixture is aged at 70-80°C for 30-60 minutes, cooled to room temperature, and toluene or xylene treated with sodium wire reflux is added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0031] S2. Preparation of co-catalyst

[0032] Under nitrogen protection, trialkylaluminum was dissolved in n-hexane solution, and the molar concentration of trialkylaluminum was 4.2×10 - 4 mol / mL, put it in an ice water bath, control the temperature to 0-5°C, add 3-methylphenol to the container at a rate of 1 drop / second, control the pressure not to exceed 0.2MPa, and place the container in an ice water bath for 4-8h to obtain a co-catalyst;

[0033] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0034] Butadiene (Bd) is dissolved in a solvent, and a co-catalyst, a main catalyst, an activator, and a molecular weight regulator are added respectively, and a polymerization reaction is carried out at 50 to 80° C. for 240 to 360 minutes to obtain a low Mooney viscosity random 1,2-polybutadiene. The Mooney viscosity is further adjusted by adjusting the polymerization reaction temperature, the amount of the catalyst, the activator, and the molecular weight regulator.

[0035] The principle of allyl bromide regulating molecular weight is that the inductive effect of bromine makes the electronegativity of its double bond close to that of the double bond on butadiene, so that allyl bromide can coordinate with the active center, and then chain transfer occurs to reduce the molecular weight. However, the boiling point of allyl bromide is close to that of the alkane solvent used, and solvent recovery is difficult. Using compounds containing bromine-allyl structure but with larger molecular weight seems to be an effective way to solve the azeotropic problem with solvents, but the molecular weight of bromine-allyl compounds is large, resulting in large steric hindrance, and the coordination ability is weak when used as a molecular weight regulator, and the molecular weight regulation effect is not good.

[0036] The method for preparing low Mooney viscosity random 1,2-polybutadiene rubber of the present invention comprises the following steps: 3-bromo-2-methylpropylene or trans-1-bromo-2-butene or a mixture of the two as a molecular weight regulator; a phosphate compound (triethyl phosphate or tripropyl phosphate or a mixture of the two) and a pentavalent molybdenum compound (molybdenum pentachloride) are used to prepare a main catalyst; a conjugated compound is used as an activator; trialkylaluminum monosubstituted with 3-methylphenol is used as a co-catalyst; the steric hindrance and electron cloud density of the active center are controlled by a ligand and an activator, thereby improving the coordination ability of the active center with the molecular weight regulator, and further improving the molecular weight adjustment ability without reducing the polymerization activity.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The method for preparing low Mooney viscosity random 1,2-polybutadiene of the present invention has high conversion rate and strong molecular weight regulation ability.

[0039] (2) The 1,2-polybutadiene prepared by the method of the present invention has a low Mooney value, low viscosity, low molecular weight, and high random 1,2-structure.

[0040] (3) The molecular weight regulator used in the present invention does not form an azeotrope with the solvent and does not affect the recovery and utilization of the solvent.

[0041] (4) The 1,2-polybutadiene prepared by the method of the present invention is applied to rubber additives and damping materials to improve the processing performance and mechanical properties of rubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the GPC chart of 1,2-polybutadiene prepared by Comparative Example 1 and Example 1 and Examples 4-6 of the present invention.

[0043] Figure 2 It is the FTIR graph of the 1,2-polybutadiene prepared in Comparative Example 2 and Examples 2-4 of the present invention. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that the following examples are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0046] The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified. The density of the triethyl phosphate is based on the relative density (g / mL, 20 / 4°C): 1.06817. The density of the tripropyl phosphate is based on the density 1.012g / mL (25°C). The following amounts of the main catalyst added are all calculated in terms of molybdenum (Mo), the amounts of the co-catalyst added are all calculated in terms of aluminum (Al), and the amounts of the molecular weight regulator added are all calculated in terms of bromine (Br). The density of 3-methylphenol in S2 in the example is 1.038g / cm 3 The butadiene concentration is 1.3 g / mL. The addition according to the molar ratio or volume ratio is performed according to the reagent state to meet the ratio formula.

[0047] Example 1

[0048] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0049] S1. Preparation of main catalyst

[0050] Under nitrogen protection, molybdenum pentachloride was added to the configuration container, triethyl phosphate was added to make the molar ratio of phosphate compound to molybdenum compound 2, aged at 70°C for 30 minutes, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0051] S2. Preparation of co-catalyst

[0052] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 0°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0053] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0054] Butadiene (Bd) was dissolved in a n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, and a 0.017 mol / mL n-hexane solution of 3-bromo-2-methylpropylene were added respectively, and a polymerization reaction was carried out at 50° C. for 240 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0055] The molar ratio of the main catalyst to butadiene is 1.5×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 6; the volume ratio of 1-methylnaphthalene to n-hexane is 0.1; the molar ratio of 3-bromo-2-methylpropylene to the main catalyst is 3.

[0056] Example 2

[0057] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0058] S1. Preparation of main catalyst

[0059] Under nitrogen protection, molybdenum pentachloride was added to the configuration container, triethyl phosphate was added to make the molar ratio of phosphate compound to molybdenum compound 3, aged at 70°C for 30 minutes, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0060] S2. Preparation of co-catalyst

[0061] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 0°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0062] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0063] Butadiene (Bd) was dissolved in a hydrogenated gasoline solution, and a co-catalyst, a main catalyst, 1-ethylnaphthalene, and a 0.017 mol / mL n-hexane solution of 3-bromo-2-methylpropylene were added respectively, and a polymerization reaction was carried out at 70° C. for 300 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0064] The molar ratio of the main catalyst to butadiene is 2×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 10; the volume ratio of 1-methylnaphthalene to n-hexane is 0.13; the molar ratio of 3-bromo-2-methylpropylene to the main catalyst is 5.

[0065] Example 3

[0066] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0067] S1. Preparation of main catalyst

[0068] Under nitrogen protection, 1g of molybdenum pentachloride was added to the configuration container, and triethyl phosphate was added to make the molar ratio of triethyl phosphate to molybdenum pentachloride 5. The mixture was aged at 70°C for 30min, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0069] S2. Preparation of co-catalyst

[0070] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 5°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0071] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0072] Butadiene (Bd) was dissolved in a cyclohexane solution, and a co-catalyst, a main catalyst, 1-propylnaphthalene, and a 0.017 mol / mL n-hexane solution of 3-bromo-2-methylpropylene were added respectively, and a polymerization reaction was carried out at 80° C. for 360 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0073] The molar ratio of the main catalyst to butadiene is 3×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 12; the volume ratio of 1-methylnaphthalene to n-hexane is 0.17; the molar ratio of 3-bromo-2-methylpropylene to the main catalyst is 10.

[0074] Example 4

[0075] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0076] S1. Preparation of main catalyst

[0077] Under nitrogen protection, 1 g of molybdenum pentachloride was added to the preparation container, and tripropyl phosphate was added to make the molar ratio of tripropyl phosphate to molybdenum pentachloride 2. The mixture was aged at 80 °C for 60 min, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5 × 10 -4mol / mL to obtain the main catalyst.

[0078] S2. Preparation of co-catalyst

[0079] Under nitrogen protection, 10 mL of triethylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 5°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 8 hours to obtain a co-catalyst.

[0080] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0081] Butadiene (Bd) was dissolved in n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, and 0.017 mol / mL n-hexane solution of trans-1-bromo-2-butene were added respectively, and polymerization reaction was carried out at 60° C. for 240 min to obtain low Mooney viscosity random 1,2-polybutadiene.

[0082] The molar ratio of the main catalyst to butadiene is 1.5×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 8; the volume ratio of 1-methylnaphthalene to n-hexane is 0.1; the molar ratio of trans-1-bromo-2-butene to the main catalyst is 3.

[0083] Example 5

[0084] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0085] S1. Preparation of main catalyst

[0086] Under nitrogen protection, 1 g of molybdenum pentachloride was added to the configuration container, and tripropyl phosphate was added to make the molar ratio of tripropyl phosphate to molybdenum pentachloride 3. The mixture was aged at 70 °C for 60 min, cooled to room temperature, and xylene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5 × 10 -4 mol / mL to obtain the main catalyst.

[0087] S2. Preparation of co-catalyst

[0088] Under nitrogen protection, 10 mL of tripropylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 2°C, 0.52 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 8 hours to obtain a co-catalyst.

[0089] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0090] Butadiene (Bd) was dissolved in a n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, and a 0.017 mol / mL n-hexane solution of trans-1-bromo-2-butene were added respectively, and a polymerization reaction was carried out at 70° C. for 240 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0091] The molar ratio of the main catalyst to butadiene is 2×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 12; the volume ratio of 1-methylnaphthalene to n-hexane is 0.13; the molar ratio of trans-1-bromo-2-butene to the main catalyst is 5.

[0092] Example 6

[0093] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0094] S1. Preparation of main catalyst

[0095] Under nitrogen protection, 1g of molybdenum pentachloride was added to the configuration container, and tripropyl phosphate was added to make the molar ratio of tripropyl phosphate to molybdenum pentachloride 5. The mixture was aged at 70°C for 60min, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0096] S2. Preparation of co-catalyst

[0097] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 2°C, 0.34 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0098] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0099] Butadiene (Bd) was dissolved in a n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, and a 0.017 mol / mL n-hexane solution of trans-1-bromo-2-butene were added respectively, and a polymerization reaction was carried out at 80° C. for 240 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0100] The molar ratio of the main catalyst to butadiene is 3×10 -4; The molar ratio of the co-catalyst to the main catalyst is 16; the volume ratio of 1-methylnaphthalene to n-hexane is 0.17; the molar ratio of trans-1-bromo-2-butene to the main catalyst is 10.

[0101] Example 7

[0102] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0103] Solvent Recovery

[0104] Butadiene polymerization was carried out under the conditions of Example 1. After the polymerization was completed, polybutadiene was precipitated with ethanol, and the remaining solution was fractionated. After removing the front fraction, the fraction at 61-76° C. was collected to remove impurities and insoluble substances such as ethanol and molecular weight regulator. The solvent after fractionation was added with sodium wire for distillation to further remove water and ethanol in n-hexane, and used as a recovery solvent for standby use.

[0105] S1. Preparation of main catalyst

[0106] Under nitrogen protection, 1g of molybdenum pentachloride was added to the configuration container, and tripropyl phosphate was added to make the molar ratio of tripropyl phosphate to molybdenum pentachloride 5. The mixture was aged at 70°C for 60min, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0107] S2. Preparation of co-catalyst

[0108] Under nitrogen protection, place 10 mL of triisobutylaluminum n-hexane solution (the molar concentration of aluminum is 4.2×10-4 mol / mL) in an ice-water bath, control the temperature at 2°C, slowly drop 0.43 mL of 3-methylphenol into the container, control the pressure not to exceed 0.2 MPa, and after the addition is completed, place the container in an ice-water bath to react for 4 hours to obtain a co-catalyst.

[0109] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0110] Butadiene (Bd) was dissolved in the recovered n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, and a 0.017 mol / mL n-hexane solution of trans-1-bromo-2-butene were added respectively, and a polymerization reaction was carried out at 80° C. for 240 min to obtain a low Mooney viscosity random 1,2-polybutadiene.

[0111] The molar ratio of the main catalyst to butadiene is 3×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 16; the volume ratio of 1-methylnaphthalene to n-hexane is 0.17; the molar ratio of trans-1-bromo-2-butene to the main catalyst is 10.

[0112] This example illustrates that the molecular weight regulator used in the present invention does not affect the recovery and utilization of the solvent.

[0113] Example 8

[0114] The method for preparing the low Mooney viscosity random 1,2-polybutadiene comprises the following steps:

[0115] S1. Preparation of main catalyst

[0116] Under nitrogen protection, 1g of molybdenum pentachloride was added to the configuration container, and triethyl phosphate was added to make the molar ratio of triethyl phosphate to molybdenum pentachloride 5. The mixture was aged at 70°C for 30min, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0117] S2. Preparation of co-catalyst

[0118] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 5°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0119] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0120] Butadiene (Bd) was dissolved in n-hexane solution, and a co-catalyst, a main catalyst, 1-methylnaphthalene, 0.017 mol / mL n-hexane solution of 3-bromo-2-methylpropylene and 1-bromo-2-butene were added respectively, and polymerization reaction was carried out at 80° C. for 240 min to obtain low Mooney viscosity random 1,2-polybutadiene.

[0121] The molar ratio of the main catalyst to butadiene is 3×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 12; the volume ratio of 1-methylnaphthalene to n-hexane is 0.17; the molar ratio of 3-bromo-2-methylpropylene to the main catalyst is 5, and the molar ratio of 1-bromo-2-butene to the main catalyst is 5.

[0122] Comparative Example 1

[0123] A method for preparing 1,2-polybutadiene comprises the following steps: using tri-n-butyl phosphate with slightly larger steric hindrance as a ligand, and the other configuration ratios and polymerization conditions are the same as those in Example 1, and polymerizing at 60° C. for 240 minutes to obtain 1,2-polybutadiene rubber. This comparative example shows that the length of the substituent chain of the phosphate ligand has a greater influence on the coordination ability of the active center and the molecular weight regulator, and when the carbon chain length of the substituent is greater than or equal to 4, the molecular weight regulation ability is weakened.

[0124] Comparative Example 2

[0125] A method for preparing 1,2-polybutadiene comprises the following steps: using triisobutyl phosphate as a ligand, the other configuration conditions and polymerization conditions are the same as those in Example 1, and polymerizing at 60° C. for 240 minutes to obtain 1,2-polybutadiene rubber. This comparative example shows that triisobutyl phosphate and tri-n-butyl phosphate have similar effects, and neither can effectively improve the coordination ability of the active center and the molecular weight regulator.

[0126] Comparative Example 3

[0127] A method for preparing 1,2-polybutadiene comprises the following steps: using triphenyl phosphate as a ligand, the other configuration conditions and polymerization conditions are the same as those in Example 1, and polymerizing at 60° C. for 240 minutes to obtain 1,2-polybutadiene rubber. This comparative example shows that when triphenyl phosphate is used as a ligand, the regulating ability of the molecular weight regulator is further weakened, and the conversion rate is reduced.

[0128] Comparative Example 4

[0129] A method for preparing 1,2-polybutadiene comprises the following steps: using trimethyl phosphate ligand, without adding activator 1-methylnaphthalene, the other configuration conditions and polymerization conditions are the same as those in Example 1, and polymerizing at 60° C. for 240 minutes to obtain 1,2-polybutadiene rubber. This comparative example shows that the conjugation effect of the activator and the active center can improve the molecular weight regulating ability of the molecular weight regulator.

[0130] Comparative Example 5

[0131] A method for preparing 1,2-polybutadiene comprises the following steps:

[0132] S1. Preparation of main catalyst

[0133] Under nitrogen protection, molybdenum pentachloride was added to the configuration container, triethyl phosphate was added to make the molar ratio of phosphate compound to molybdenum compound 3, aged at 70°C for 30 minutes, cooled to room temperature, and toluene treated with sodium wire reflux was added to dilute the concentration of molybdenum to 5×10 -4 mol / mL to obtain the main catalyst.

[0134] S2. Preparation of co-catalyst

[0135] Under nitrogen protection, 10 mL of triisobutylaluminum n-hexane solution (aluminum molar concentration of 4.2×10 -4 mol / mL) was placed in an ice water bath, the temperature was controlled at 0°C, 0.43 mL of 3-methylphenol was slowly added dropwise to the container, the pressure was controlled not to exceed 0.2 MPa, and after the addition was completed, the container was placed in an ice water bath for reaction for 4 hours to obtain a co-catalyst.

[0136] S3. Preparation of low Mooney viscosity random 1,2-polybutadiene

[0137] Butadiene (Bd) was dissolved in n-hexane solution, and a co-catalyst and a main catalyst were added respectively, and polymerization reaction was carried out at 60°C for 240 minutes to obtain 1,2-polybutadiene. The molar ratio of the main catalyst to butadiene was 2×10 -4 ; The molar ratio of the co-catalyst to the main catalyst is 10.

[0138] The 1,2-polybutadiene prepared in the above examples and comparative examples was analyzed for copolymer composition sequence distribution and microstructure by nuclear magnetic resonance spectrometer and infrared spectrometer, the molecular weight and molecular weight distribution index of the copolymer was analyzed by gel permeation chromatography, and the Mooney viscosity of the polymer was analyzed by Mooney viscometer. The 1,2-structure content was calculated based on the 738, 911, 967 cm -1 They are the characteristic peaks of cis-1,4, 1,2 and trans-1,4 structures respectively, and the peak areas of these three characteristic peaks are calculated. The contents mentioned here are all mass contents. Mn is the number average molecular weight, ML is the ML100 (1+4) Mooney viscosity, and the results are shown in Table 1.

[0139] Table 1 Test results

[0140] project Polymerization conversion rate / % 1,2-Structure content / % Mn ML Example 1 85 90 21.2 38 Example 2 90 85 18.5 35 Example 3 95 82 13.2 20 Example 4 82 93 20.8 38 Example 5 88 88 15.5 32 Example 6 92 83 12.3 20 Example 7 84 90 20.5 37 Example 8 87 87 17.5 32 Comparative Example 1 76 91 33.2 88 Comparative Example 2 75 88 34.1 87 Comparative Example 3 ＜65 92 38.3 90 Comparative Example 4 86 89 25.1 60 Comparative Example 5 88 85 45 85

[0141] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing low Mooney viscosity random 1,2-polybutadiene, characterized in that: The following steps are involved: S1. Preparation of main catalyst Under protective gas, the molybdenum compound and the phosphate compound are mixed, aged at 70-80° C. for 30-60 minutes, cooled to room temperature, and diluted to obtain a main catalyst; S2. Preparation of co-catalyst Under protective gas, the alkane solution of trialkylaluminum is added dropwise to the container with the aryloxy ligand at 0-5°C, the pressure is controlled not to exceed 0.2MPa, and after the addition is completed, the mixture is reacted in an ice-water bath for 4-8h to obtain a co-catalyst; S3. Preparation of low Mooney viscosity random 1,2-polybutadiene Butadiene is dissolved in a solvent, a co-catalyst, a main catalyst, an activator and a molecular weight regulator are added respectively, and polymerization is carried out at 50 to 80° C. for 240 to 360 minutes to obtain low Mooney viscosity random 1,2-polybutadiene.

2. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The phosphate compound in S1 is triethyl phosphate or tripropyl phosphate, and the molar ratio of the phosphate compound to the molybdenum compound is 2-5.

3. The method for preparing low Mooney viscosity random high 1,2-polybutadiene according to claim 1, characterized in that: The trialkylaluminum in S2 is triethylaluminum, tributylaluminum or tripropylaluminum.

4. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The aryloxy ligand in S2 is 3-methylphenol; the molar ratio of the aryloxy ligand to trialkylaluminum is 0.8 to 1.

2.

5. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The solvent in S3 is hydrogenated gasoline or n-hexane or cyclohexane.

6. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The amount of the main catalyst added in S3 is calculated based on molybdenum, and the molar ratio of the main catalyst to butadiene is 1.5×10 -4 ~3×10 -4 ; The amount of the co-catalyst added is calculated based on aluminum, and the molar ratio of the co-catalyst to the main catalyst is 8 to 16.

7. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The activator in S3 is 1-methylnaphthalene, 1-ethylnaphthalene or 1-propylnaphthalene, and the volume ratio of the activator to the solvent is 0.1 to 0.

17.

8. The method for preparing low Mooney viscosity random 1,2-polybutadiene according to claim 1, characterized in that: The molecular weight regulator in S3 is 3-bromo-2-methylpropene or trans-1-bromo-2-butene or a mixture of the two, and the added amount is calculated based on bromine. The molar ratio of the molecular weight regulator to the main catalyst is 3-10.

9. A low Mooney viscosity random 1,2-polybutadiene, characterized in that: The low Mooney viscosity random 1,2-polybutadiene is prepared by the preparation method of any one of claims 1 to 8.

10. An application of the low Mooney viscosity random 1,2-polybutadiene according to claim 9, characterized in that: Used in rubber additives and damping materials.

Images