Hydrogenated nitrile rubber and preparation method thereof

Abstract

The invention relates to the field of rubber, and provides hydrogenated butadiene-acrylonitrile rubber and a preparation method thereof.The preparation method comprises the following steps that S1, acrylonitrile, a molecular weight regulator, potassium persulfate, sodium dodecyl benzene sulfonate and deionized water are added into a reaction kettle, vacuumizing is conducted, inert gas is introduced, butadiene is added, a sodium bicarbonate aqueous solution is added to adjust the pH to be 10-11, and a mixture is obtained; stirring at 23-27 DEG C for 8-10 hours, washing and drying to obtain nitrile rubber for later use; and S2, adding the nitrile rubber obtained in the step S1 into acetone in an inert atmosphere, stirring, adding a porphyrin-based catalyst, stirring, introducing hydrogen, carrying out a hydrogenation reaction, cooling to room temperature, extruding a material, precipitating, and drying to obtain the hydrogenated nitrile rubber. The hydrogenated butadiene-acrylonitrile rubber provided by the invention has the characteristics of high stability, high hydrogenation activity and high hydrogenation degree.

Description

Technical Field

[0001] The present invention relates to the field of rubber, and particularly to a hydrogenated nitrile rubber and a preparation method thereof. Background Art

[0002] Hydrogenated nitrile rubber has good oil resistance, and due to its highly saturated structure, it has good heat resistance, chemical corrosion resistance, ozone resistance, and relatively high compression set resistance. At the same time, hydrogenated nitrile rubber also has high strength, high tear resistance, and excellent wear resistance, etc. It is one of the rubbers with extremely excellent comprehensive performance.

[0003] At present, there are mainly two methods for preparing hydrogenated nitrile rubber. One is homogeneous hydrogenation method, and the other is heterogeneous hydrogenation method. Among them, the homogeneous hydrogenation method means that the active component of the catalyst is dispersed in the polymer solution in molecular form, and under a certain hydrogen pressure, catalytic hydrogenation reaction is carried out on the polymer. It has the advantages of easy control of reaction conditions and stable product performance, and is one of the mainstream methods for industrial production at present. However, the homogeneous hydrogenation method has a common disadvantage that the catalyst is difficult to separate, which will lead to an increase in components and even affect the mechanical processing performance of the polymer. The heterogeneous hydrogenation method often uses supported noble metal catalysts, which can well solve the problem of difficult separation of the catalyst. However, the heterogeneous hydrogenation method still has disadvantages such as insufficient binding stability between the support and the noble metal, low hydrogenation activity of the catalyst, and difficult control of reaction conditions, etc., all of which will have a certain impact on the hydrogenation degree of hydrogenated nitrile rubber.

[0004] Patent CN 104592423A discloses a preparation method of hydrogenated nitrile rubber. This preparation method uses acetone as a solvent and colloidal palladium as a catalyst, and reacts by introducing hydrogen under the conditions of 50°C and 5 MPa for 4 h. The saturation degree of the prepared hydrogenated nitrile rubber reaches 90%, and it has a relatively high hydrogenation degree. However, the colloidal palladium catalyst selected in this application has a problem of poor stability, which may lead to a decrease in the service life of the prepared hydrogenated nitrile rubber.

[0005] Therefore, there is an urgent need in the market for a hydrogenated nitrile rubber with high stability, high hydrogenation activity and high hydrogenation degree. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention is based on the method of preparing hydrogenated nitrile rubber by heterogeneous hydrogenation method, optimizes the synthesis method and reaction conditions of this preparation method, and prepares a new type of porphyrin-based catalyst, which solves the problems of insufficient stability, low hydrogenation activity and low hydrogenation degree in the existing preparation methods of hydrogenated nitrile rubber.

[0007] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] On the one hand, the present invention provides a method for preparing hydrogenated nitrile rubber, comprising the following steps:

[0009] S1. Add acrylonitrile, molecular weight regulator, potassium persulfate, sodium dodecylbenzenesulfonate and deionized water into a reaction kettle, evacuate, introduce an inert gas, add butadiene, add an aqueous sodium bicarbonate solution to adjust the pH to 10 - 11, stir at 23 - 27 °C for 8 - 10 h, wash and dry to obtain nitrile rubber for standby;

[0010] S2. Under an inert atmosphere, add the nitrile rubber obtained in step S1 into acetone, stir, add a porphyrin - based catalyst, stir, introduce hydrogen for hydrogenation reaction, cool to room temperature, extrude the material, precipitate and dry to obtain hydrogenated nitrile rubber.

[0011] In some embodiments of the present invention, the mass ratio of acrylonitrile to butadiene in step S1 is 1:(2 - 3).

[0012] Preferably, the mass ratio of acrylonitrile to butadiene in step S1 is 1:(2 - 2.5).

[0013] More preferably, the mass ratio of acrylonitrile to butadiene in step S1 is 1:2.33.

[0014] In some embodiments of the present invention, the mass ratio of the sum of acrylonitrile and butadiene, molecular weight regulator, potassium persulfate and sodium dodecylbenzenesulfonate in step S1 is 1:(0.05 - 0.07):(0.016 - 0.02):(0.03 - 0.05).

[0015] Preferably, the mass ratio of the sum of acrylonitrile and butadiene, molecular weight regulator, potassium persulfate and sodium dodecylbenzenesulfonate in step S1 is 1:0.06:0.018:0.04.

[0016] In some embodiments of the present invention, the molecular weight regulator in step S1 is α - methylstyrene dimer.

[0017] The applicant uses α - methylstyrene dimer to replace the commonly used mercaptan - based molecular weight regulator. The α - methylstyrene dimer molecule contains no sulfur, is odorless, safe and environmentally friendly, and is a green and environmentally friendly molecular weight regulator with high regulation efficiency.

[0018] In some embodiments of the present invention, the mass ratio of nitrile rubber to porphyrin - based catalyst in step S2 is 1:(0.1 - 0.2).

[0019] Preferably, the mass ratio of nitrile rubber to porphyrin - based catalyst in step S2 is 1:0.15.

[0020] In some embodiments of the present invention, the preparation method of the porphyrin-based catalyst in step S2 includes the following steps:

[0021] (1) Mix tetrahydroxyphenyl porphyrin, palladium acetate and cobalt acetate, add anhydrous ethanol and dichloromethane, heat under reflux, rotary evaporate, elute, and dry to obtain product 1 for standby;

[0022] (2) Mix product 1, p-bromobenzaldehyde and potassium carbonate, introduce an inert gas, add DMF, introduce an inert gas, heat under reflux, distill under reduced pressure, dry, elute, and dry to obtain product 2 for standby;

[0023] (3) Mix product 2 and tetrakis(4-aminophenyl)methane, add a mixed solvent, freeze, evacuate, introduce an inert gas, heat, react at 115 - 125 °C for 71 - 73 h, take the solid, wash, Soxhlet extract, extract, and dry to obtain the porphyrin-based catalyst.

[0024] Among them, in the step (2), the mass ratio of product 1 to p-bromobenzaldehyde is 1:(0.4 - 0.6).

[0025] In some embodiments of the present invention, in the step (1), the mass ratio of tetrahydroxyphenyl porphyrin, palladium acetate and cobalt acetate is 1:(5.5 - 6.5):(2.5 - 3.5).

[0026] Preferably, in the step (1), the mass ratio of tetrahydroxyphenyl porphyrin, palladium acetate and cobalt acetate is 1:6:3.

[0027] In some embodiments of the present invention, in the step (3), the mass ratio of tetrakis(4-aminophenyl)methane to product 2 is 1:(2.5 - 3.5).

[0028] Preferably, in the step (3), the mass ratio of tetrakis(4-aminophenyl)methane to product 2 is 1:3.

[0029] Currently, the preparation method of hydrogenated nitrile rubber is gradually developing towards heterogeneous reactions. Porphyrin is an important compound existing in organisms. Metalloporphyrins have very good catalytic effects, but metalloporphyrins are expensive and in the catalytic system with metalloporphyrins as catalysts, porphyrins are prone to aggregation precipitation or self-oxidation inactivation, resulting in a decrease in catalytic yield. Compared with metalloporphyrins, porphyrin-based covalent organic polymers have good stability and thus have good application prospects in the field of heterogeneous catalysis.

[0030] The applicant selects tetra-hydroxyphenyl porphyrin to react with palladium acetate and cobalt acetate, fixing palladium ions and cobalt ions in the structure of tetra-hydroxyphenyl porphyrin (obtaining Product 1). Palladium ions are the active components for the hydrogenation catalytic reaction, and cobalt ions are the auxiliary components for the hydrogenation catalyst reaction. By controlling the ratio of the two metal ions, a synergistic hydrogenation catalysis effect can be achieved. Further, the applicant reacts Product 1 with excessive p-bromobenzaldehyde to introduce an aldehyde group structure into the structure of Product 1, and uses the aldehyde group structure to react with the amino group of tetrakis(4-aminophenyl)methane to synthesize a porphyrin-based covalent organic polymer with an imine bond, that is, a porphyrin-based catalyst. The covalent bond connection method makes the porphyrin-based catalyst have good stability, and the three-dimensional structure of tetrakis(4-aminophenyl)methane makes the synthesized porphyrin-based catalyst have a high specific surface area, thereby making the porphyrin-based catalyst have higher hydrogenation catalytic activity. Even further, the applicant unexpectedly discovers that the prepared porphyrin-based catalyst has good hydrogen storage and adsorption capabilities, is a good hydrogen storage material, and can make the synthesized hydrogenated nitrile rubber have a higher hydrogenation degree.

[0031] In some embodiments of the present invention, the conditions for introducing hydrogen for the hydrogenation reaction in step S2 are: the pressure is 5 - 6 MPa, the temperature is 45 - 55 °C, and the time is 3 - 4 h.

[0032] Preferably, the conditions for introducing hydrogen for the hydrogenation reaction in step S2 are: the pressure is 5.5 MPa, the temperature is 50 °C, and the time is 3.5 h.

[0033] On the other hand, the present invention also provides a hydrogenated nitrile rubber obtained by the preparation method described in the above technical solution, and the hydrogenation degree of the hydrogenated nitrile rubber is not less than 97.5%.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention provides a preparation method for hydrogenated nitrile rubber. Based on the heterogeneous hydrogenation method, the synthesis method and reaction conditions of this preparation method are optimized, and a new type of porphyrin-based catalyst is prepared. Through the synergistic effect among the components, the prepared hydrogenated nitrile rubber has the characteristics of high stability, high hydrogenation activity and high hydrogenation degree.

[0036] (2) The present invention selects α-methylstyrene dimer as the molecular weight regulator, which has the advantages of high regulation efficiency and is also safe and environmentally friendly.

[0037] (3) In the present invention, tetrahydroxyphenyl porphyrin reacts with palladium acetate and cobalt acetate, then reacts with an excessive amount of p-bromobenzaldehyde to introduce an aldehyde group structure, and finally undergoes a Schiff base reaction with tetra(4-aminophenyl)methane to synthesize a porphyrin-based catalyst, which has the advantages of high stability and high specific surface area, thereby enabling the prepared hydrogenated nitrile rubber to have a high hydrogenation degree.

[0038] (4) The hydrogenation degree of the hydrogenated nitrile rubber obtained by the preparation method of the present invention is not less than 97.5%, and it has the characteristics of high stability, high hydrogenation activity and high hydrogenation degree. Specific Embodiments

[0039] The present invention will be described below in conjunction with specific implementation embodiments. It should be noted that the following examples are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0040] In the following examples and comparative examples, except for the porphyrin-based catalyst, the compound monomers and related reagents used can all be purchased from the market. Among them, α-methylstyrene dimer is purchased from Shandong Shouhua Chemical Co., Ltd.

[0041] Preparation Example 1

[0042] The synthesis method of porphyrin-based catalyst A includes the following steps:

[0043] (1) Mix 1.5 g of tetrahydroxyphenyl porphyrin, 10.5 g of palladium acetate and 4.5 g of cobalt acetate, add 100 ml of absolute ethanol and 100 ml of dichloromethane, heat under reflux at 140 °C for 4 h, rotary evaporate, and use 200 ml of a dichloromethane solution of 8 wt% absolute ethanol as the eluent for elution, and dry at 60 °C for 8 h to obtain Product 1 for standby;

[0044] (2) Mix 3 g of Product 1, 1.5 g of p-bromobenzaldehyde and 0.7 g of potassium carbonate, introduce nitrogen, add 150 ml of DMF, introduce nitrogen, heat under reflux at 120 °C for 24 h, carry out vacuum distillation, dry at 105 °C for 8 h, use 100 ml of a dichloromethane solution of 10 wt% absolute ethanol as the eluent for elution, and dry at 60 °C for 8 h to obtain Product 2 for standby;

[0045] (3) Mix 3 g of product 2 and 1 g of tetrakis(4-aminophenyl)methane, add 20 ml of a mixed solvent (18 ml of o-dichlorobenzene, 1 ml of n-butanol, and 1 ml of glacial acetic acid), freeze with liquid nitrogen for 30 min, evacuate, introduce nitrogen, heat at 150 °C for 2 h, react at 120 °C for 72 h, take the solid, wash it successively with dioxane, acetone, and tetrahydrofuran until colorless, perform Soxhlet extraction with THF and acetone for 24 h respectively, extract, and dry at 105 °C for 8 h to obtain the porphyrin-based catalyst A.

[0046] Preparation Example 2

[0047] Porphyrin-based catalyst B, the specific implementation method is the same as that of porphyrin-based catalyst A, the difference is: in step (1), replace the mass of palladium acetate with 7.8 g.

[0048] Preparation Example 3

[0049] Porphyrin-based catalyst C, the specific implementation method is the same as that of porphyrin-based catalyst A, the difference is: in step (1), replace the mass of cobalt acetate with 3.3 g.

[0050] Preparation Example 4

[0051] Porphyrin-based catalyst D, the specific implementation method is the same as that of porphyrin-based catalyst A, the difference is: in step (3), replace the mass of tetrakis(4-aminophenyl)methane with 0.75 g.

[0052] Example 1

[0053] A preparation method of hydrogenated nitrile rubber, comprising the following steps:

[0054] S1. Add 30 g of acrylonitrile, 6 g of α-methylstyrene dimer, 1.8 g of potassium persulfate, 4 g of sodium dodecylbenzenesulfonate, and 200 ml of deionized water to a reaction kettle, evacuate, introduce nitrogen, add 70 g of butadiene, add a 5 wt% aqueous sodium bicarbonate solution to adjust the pH = 10.5, stir at 25 °C for 9 h, wash with 300 ml of deionized water, and dry at 105 °C for 5 h to obtain the nitrile rubber for standby;

[0055] S2. Under a nitrogen atmosphere, add 30 g of the nitrile rubber obtained in step S1 to 100 ml of acetone, stir for 1 h, add 4.5 g of porphyrin-based catalyst A, stir for 5 min, introduce hydrogen at 50 °C and 5.5 MPa for hydrogenation reaction for 3.5 h, cool to room temperature, extrude the material, precipitate with anhydrous methanol, and dry at room temperature for 48 h to obtain the hydrogenated nitrile rubber.

[0056] Example 2

[0057] A preparation method of hydrogenated nitrile rubber, comprising the following steps:

[0058] S1. Add 30 g of acrylonitrile, 4.5 g of α-methylstyrene dimer, 1.44 g of potassium persulfate, 2.7 g of sodium dodecylbenzenesulfonate and 200 ml of deionized water into a reaction kettle, evacuate, introduce nitrogen, add 60 g of butadiene, add a 5 wt% aqueous sodium bicarbonate solution to adjust the pH to 10, stir at 23 °C for 10 h, wash with 300 ml of deionized water, and dry at 105 °C for 5 h to obtain nitrile rubber for standby;

[0059] S2. Under a nitrogen atmosphere, add 30 g of the nitrile rubber obtained in step S1 into 100 ml of acetone, stir for 1 h, add 3 g of porphyrin-based catalyst A, stir for 5 min, introduce hydrogen gas at 45 °C and 5 MPa for a hydrogenation reaction for 4 h, cool to room temperature, extrude the material, precipitate with anhydrous methanol, and dry at room temperature for 48 h to obtain hydrogenated nitrile rubber.

[0060] Example 3

[0061] A preparation method of hydrogenated nitrile rubber, comprising the following steps:

[0062] S1. Add 30 g of acrylonitrile, 8.4 g of α-methylstyrene dimer, 2.4 g of potassium persulfate, 6 g of sodium dodecylbenzenesulfonate and 200 ml of deionized water into a reaction kettle, evacuate, introduce nitrogen, add 90 g of butadiene, add a 5 wt% aqueous sodium bicarbonate solution to adjust the pH to 11, stir at 27 °C for 8 h, wash with 300 ml of deionized water, and dry at 105 °C for 5 h to obtain nitrile rubber for standby;

[0063] S2. Under a nitrogen atmosphere, add 30 g of the nitrile rubber obtained in step S1 into 100 ml of acetone, stir for 1 h, add 6 g of porphyrin-based catalyst A, stir for 5 min, introduce hydrogen gas, and introduce hydrogen gas at 55 °C and 6 MPa for a hydrogenation reaction for 3 h, cool to room temperature, extrude the material, precipitate with anhydrous methanol, and dry at room temperature for 48 h to obtain hydrogenated nitrile rubber.

[0064] Example 4

[0065] This example provides a preparation method of hydrogenated nitrile rubber. The specific implementation manner is the same as that of Example 1, except that the mass of the porphyrin-based catalyst A in step S2 is 2.7 g.

[0066] Example 5

[0067] This example provides a preparation method of hydrogenated nitrile rubber. The specific implementation manner is the same as that of Example 1, except that the mass of the porphyrin-based catalyst A in step S2 is 6.6 g.

[0068] Example 6

[0069] This example provides a method for preparing hydrogenated nitrile rubber. The specific implementation is the same as that of Example 1, except that the porphyrin-based catalyst B replaces the porphyrin-based catalyst A in equal amounts.

[0070] Example 7

[0071] This example provides a method for preparing hydrogenated nitrile rubber. The specific implementation is the same as that of Example 1, except that the porphyrin-based catalyst C replaces the porphyrin-based catalyst A in equal amounts.

[0072] Example 8

[0073] This example provides a method for preparing hydrogenated nitrile rubber. The specific implementation is the same as that of Example 1, except that the porphyrin-based catalyst D replaces the porphyrin-based catalyst A in equal amounts.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing hydrogenated nitrile rubber. The specific implementation is the same as that of Example 1, except that palladium acetate replaces the porphyrin-based catalyst A in equal amounts.

[0076] Performance Test

[0077] The hydrogenation degree of the hydrogenated nitrile rubber prepared in the above Examples 1-8 and Comparative Example 1 was tested, and the test results are shown in Table 1.

[0078] The hydrogenation degree of the hydrogenated nitrile rubber was tested by the bromine-iodine method with reference to the standard ASTM D5902-05(2019).

[0079] Table 1

[0080]

[0081]

[0082] As can be seen from the data in Table 1, the hydrogenated nitrile rubber in Examples 1-3 of the present invention generally has a high hydrogenation degree, and the highest hydrogenation degree can reach 98.5%. The higher the hydrogenation degree, the better the stability of the prepared hydrogenated nitrile rubber is proved from the side. Among them, in Examples 4-5, the addition amount of the porphyrin-based catalyst was changed, so that the porphyrin-based catalyst could not fully promote the hydrogenation reaction of nitrile rubber, resulting in a significant decrease in the hydrogenation degree of the hydrogenated nitrile rubber; in Examples 6-8, the reaction ratios between palladium acetate, cobalt acetate and tetrahydroxyphenylporphyrin during the synthesis of the porphyrin-based catalyst, and the reaction ratio between the aldehyde group and tetra(4-aminophenyl)methane during the Schiff base reaction were changed, resulting in a decrease in the specific surface area, stability and hydrogen storage capacity of the porphyrin-based catalyst, and further leading to a decrease in the hydrogenation degree of the hydrogenated nitrile rubber; Comparative Example 1 used palladium acetate to equally replace the porphyrin-based catalyst A, and the test found that the hydrogenation degree of the hydrogenated nitrile rubber showed poor results.

[0083] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of hydrogenated nitrile rubber, characterized in that, It includes the following steps: S1. Add acrylonitrile, molecular weight regulator, potassium persulfate, sodium dodecylbenzenesulfonate and deionized water into a reaction kettle, evacuate to vacuum, introduce inert gas, add butadiene, add aqueous sodium bicarbonate solution to adjust the pH to 10 - 11, stir at 23 - 27 °C for 8 - 10 h, wash and dry to obtain nitrile rubber for standby; S2. Under an inert atmosphere, add the nitrile rubber obtained in step S1 into acetone, stir, add a porphyrin - based catalyst, stir, introduce hydrogen for hydrogenation reaction, cool to room temperature, extrude the material, precipitate and dry to obtain hydrogenated nitrile rubber.

2. The preparation method of the hydrogenated nitrile rubber according to claim 1, characterized in that, In step S1, the mass ratio of acrylonitrile to butadiene is 1:(2 - 3).

3. The preparation method of the hydrogenated nitrile rubber according to claim 1, characterized in that, In step S1, the mass ratio of the sum of acrylonitrile and butadiene, molecular weight regulator, potassium persulfate and sodium dodecylbenzenesulfonate is 1:(0.05 - 0.07):(0.016 - 0.02):(0.03 - 0.05).

4. The preparation method of the hydrogenated nitrile rubber according to claim 1, wherein, In step S1, the molecular weight regulator is α - methylstyrene dimer.

5. The preparation method of the hydrogenated nitrile rubber according to claim 1, characterized in that, In step S2, the mass ratio of nitrile rubber to porphyrin - based catalyst is 1:(0.1 - 0.2).

6. The preparation method of the hydrogenated nitrile rubber according to claim 1, wherein, The preparation method of the porphyrin - based catalyst in step S2 includes the following steps: (1) Mix tetrahydroxyphenylporphyrin, palladium acetate and cobalt acetate, add anhydrous ethanol and dichloromethane, heat under reflux, rotary evaporate, elute and dry to obtain product 1 for standby; (2) Mix product 1, p - bromobenzaldehyde and potassium carbonate, introduce inert gas, add DMF, introduce inert gas, heat under reflux, distill under reduced pressure, dry, elute and dry to obtain product 2 for standby; (3) Mix product 2 and tetrakis(4 - aminophenyl)methane, add a mixed solvent, freeze, evacuate to vacuum, introduce inert gas, heat, react at 115 - 125 °C for 71 - 73 h, take the solid, wash, Soxhlet extract, extract and dry to obtain the porphyrin - based catalyst.

7. The preparation method of the hydrogenated nitrile rubber according to claim 6, characterized in that, In step (1), the mass ratio of tetrahydroxyphenylporphyrin, palladium acetate and cobalt acetate is 1:(5.5 - 6.5):(2.5 - 3.5).

8. The preparation method of the hydrogenated nitrile rubber according to claim 6, characterized in that, In step (3), the mass ratio of tetrakis(4 - aminophenyl)methane to product 2 is 1:(2.5 - 3.5).

9. The preparation method of the hydrogenated nitrile rubber according to claim 1, characterized in that, The conditions for introducing hydrogen for hydrogenation reaction in step S2 are: pressure is 5 - 6 MPa, temperature is 45 - 55 °C, and time is 3 - 4 h.

10. The preparation method of the hydrogenated nitrile rubber according to any one of claims 1-9, characterized in that, The hydrogenation degree of the prepared hydrogenated nitrile rubber is not less than 97.5%.

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