Preparation and application of novel coupling agent for carbon black

Abstract

The invention belongs to the technical field of carbon black reinforced rubber materials, and particularly relates to preparation and application of a novel coupling agent for carbon black. A novel coupling agent for carbon black with amino and an azine ring is self-made and is applied to a carbon black reinforced rubber material, so that the compatibility with the carbon black is high, the dispersion of the carbon black is greatly improved, the agglomeration among the carbon black is reduced, and the coupling agent can react with rubber, so that the carbon black is better combined with the rubber, and the rubber is more stable. Therefore, various properties of the carbon black reinforced rubber material are improved, and wider possibility is provided for wide application of the carbon black reinforced rubber material.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon black reinforced rubber materials, and particularly relates to the preparation and application of a novel coupling agent for carbon black. Background Art

[0002] In the preparation of rubber, carbon black (CB) is an essential part as a reinforcing filler. Due to the strong van der Waals force between carbon black particles, large agglomerates are easily formed in the rubber matrix, resulting in serious hysteresis losses in the rubber composite under dynamic deformation due to the internal friction between carbon black particles in the agglomerates, which brings adverse factors to the application of rubber products under dynamic use conditions.

[0003] To balance the contradiction between reinforcement and the increase in hysteresis loss in CB-filled rubber composites, researchers often add an additive. The most characteristic feature of the molecular structure of this additive is that it contains two groups with different chemical properties in the molecule. One is a group that is inorganic-philic and easily reacts with the surface of inorganic substances; the other is an organic-philic group that can react with rubber or form hydrogen bonds and dissolve in it. Therefore, this additive is regarded as a "molecular bridge" to improve the interfacial interaction between inorganic and organic substances, thereby greatly improving the performance of the composite material.

[0004] Currently, common methods for improving the compatibility between carbon black and rubber include adding coupling agents. For example, silane coupling agents are commonly used for the surface modification of white carbon black, but their modification effect on carbon black is limited. Traditional coupling agents are difficult to effectively modify both carbon black and rubber simultaneously.

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a novel coupling agent for carbon black. This coupling agent not only has a strong affinity with carbon black, greatly improves the dispersion of carbon black, reduces the agglomeration between carbon black, but also can react with rubber, enabling better combination of carbon black and rubber, thereby enhancing the various properties of carbon black reinforced rubber materials and providing broader possibilities for the wide application of carbon black reinforced rubber materials. Summary of the Invention

[0006] The purpose of the present invention is to provide the preparation and application of a novel coupling agent for carbon black. By synthesizing a novel coupling agent for carbon black with amino and pyrazine rings and using it in carbon black reinforced rubber materials, the various properties of carbon black reinforced rubber materials are improved.

[0007] The chemical structural formula of the novel coupling agent for carbon black (LSH coupling agent) is as follows:

[0008]

[0009] The preparation method of the novel coupling agent for carbon black includes the following steps:

[0010] S1. Add the solvent, reaction raw materials and catalyst into a round-bottom flask. After reacting at 78 °C for 12 - 16 h, cool to room temperature, add dichloromethane and deionized water, then filter. After extraction, collect the organic layer, dry it with anhydrous CaCl₂, and concentrate it under reduced pressure to obtain crude residue oil;

[0011] S2. Elute and purify the crude residue oil on silica gel by flash chromatography to obtain the coupling agent.

[0012] Preferably, the solvent is anhydrous ethanol.

[0013] Selecting the polar protic solvent ethanol as the solvent can not only effectively dissolve 5-amino-2-cyanopyrimidine, disperse insoluble sulfur particles at the same time, increase their contact area, but also interact with the reactants through hydrogen bonds to form a homogeneous reaction system. While promoting the nucleophilic addition reaction of nitrile group and hydrazine, it reduces the condensation side reaction between amino group and hydrazine. In addition, ethanol has a relatively low boiling point. By controlling the reflux temperature, it not only avoids side reactions caused by high temperature, but also maintains the dynamic balance of the reaction system through continuous reflux to promote the progress of the reaction.

[0014] Preferably, the reaction raw materials are 5-amino-2-cyanopyrimidine and hydrazine hydrate, and the molar ratio is 1:(4.5 - 5.5).

[0015] Selecting 5-amino-2-cyanopyrimidine and hydrazine hydrate as raw materials, ethanol as the solvent, and insoluble sulfur as the catalyst not only simplifies the process, but also avoids overreaction or accumulation of by-products, thereby improving the yield and purity of the required coupling agent obtained. This may be due to the directional condensation effect of hydrazine hydrate, which not only reduces the nitrile group of 5-amino-2-cyanopyrimidine to an amino group, but also provides the nitrogen atoms required for cyclization, and drives the alternating condensation of diazine ring and tetrazine ring. By regulating the molar ratio of hydrazine hydrate and 5-amino-2-cyanopyrimidine, the cyclization sequence is precisely regulated, and a linear polyheterocyclic skeleton of "amino-diazine ring-tetrazine ring-diazine ring-amino" is constructed, realizing the synergistic design of a high-nitrogen rigid skeleton and a flexible amino terminal group.

[0016] Preferably, the catalyst is insoluble sulfur.

[0017] Selecting insoluble sulfur as the catalyst, on the one hand, it can not only act as a dehydrogenating agent to promote the [4+2] cycloaddition of nitrile group and hydrazine to form a tetrazine ring, but also catalyze the cyclization reaction through surface active sites to improve the reaction efficiency. On the other hand, insoluble sulfur with a high specific surface area can not only adsorb amino groups, reduce their reaction activity, but also form weak coordination bonds with amino groups to prevent them from participating in condensation or oxidation, thus inhibiting the occurrence of side reactions.

[0018] Preferably, the molar ratio of the reaction raw materials and the catalyst is (2 - 4):1.

[0019] Preferably, the solid-liquid ratio of the solvent to the reaction raw material is 1 mL:(140 - 150) mg.

[0020] Preferably, the addition amounts of dichloromethane and water are respectively 2 - 3 times and 1 - 2 times the volume of the solvent.

[0021] The specific conditions for elution and purification are as follows: the eluent is petroleum ether / ethyl acetate, and gradient elution is carried out at volume ratios of 1:1, 2:1, and 4:1. After collecting the target components and combining them, the solvent is removed by rotary evaporation and then vacuum dried.

[0022] Finally, gradient elution with petroleum ether / ethyl acetate is adopted to effectively separate polycyclic products with small polarity differences from by-products, further improving the product purity.

[0023] The application of the novel coupling agent for carbon black is applied to carbon black-reinforced rubber materials.

[0024] For the carbon black-reinforced rubber material, calculated by weight, its preparation raw materials include 100 parts of natural rubber, 45 - 55 parts of carbon black, 0.1 - 2 parts of the novel coupling agent for carbon black, 3 - 5 parts of zinc oxide, 1 - 3 parts of stearic acid, 1 - 3 parts of antioxidant 6PPD, 0.5 - 2 parts of protective wax, 0.5 - 1 part of sulfur, and 1 - 2 parts of accelerator NS.

[0025] Preferably, the tensile strength of the natural rubber is ≥18 MPa, the plasticity retention rate is ≥60%, and the impurity content is ≤0.05%.

[0026] In some preferred embodiments, the natural rubber is purchased from Shanghai Cunsi Industry Co., Ltd., imported natural rubber from Vietnam.

[0027] Preferably, the oil absorption value of the carbon black is 120 - 134 10 -5 m3 / kg, and the residue on a 325-mesh sieve is ≤0.001%.

[0028] In some preferred embodiments, the carbon black is purchased from Tianjin Moke New Material Technology Co., Ltd., carbon black N134, N234.

[0029] Preferably, the average particle size of the zinc oxide is 25 - 35 nm, and the ignition loss is ≤0.2%.

[0030] In some preferred embodiments, the zinc oxide is purchased from Beijing Decodaojin Technology Co., Ltd., rubber nano-zinc oxide.

[0031] Preferably, the dropping melting point of the protective wax is 67 - 72 °C, and the kinematic viscosity at 100 °C is 5.0 - 8.5 mm2 / s.

[0032] The protective wax is purchased from Guangzhou Chuangbo Chemical Co., Ltd., rubber protective wax CB-3.

[0033] The preparation method of the carbon black reinforced rubber material comprises the following steps: adding raw materials into an internal mixer for internal mixing, then passing through a two-roll mill for open mixing and a vulcanizer for vulcanization to obtain the product.

[0034] Preferably, the preparation method of the carbon black reinforced rubber material comprises the following steps:

[0035] A1. First-stage mixing: Control the temperature of the internal mixer at 80 - 100 °C, the rotation speed at 85 - 95 r / min, add natural rubber, after internal mixing for 1 min, add carbon black and a new coupling agent for carbon black, mix for 2 - 4 min, then add zinc oxide, stearic acid, antioxidant 6PPD, and protective wax and mix for 1 - 3 min, and discharge the rubber at 145 - 155 °C to obtain the first-stage mixed rubber.

[0036] A2. Second-stage mixing: Adjust the rotor speed to 55 - 65 r / min, the temperature to 80 - 100 °C, add the first-stage mixed rubber and mix for 1 min, then add sulfur and accelerator NS and mix for 1 - 2 min, and discharge the rubber at 115 - 125 °C to obtain the second-stage mixed rubber.

[0037] A3. Open mixing on a two-roll mill: Put the second-stage mixed rubber into a two-roll open mill, make it wrap around the roll, cut the rubber left and right 2 times, thin pass 6 times, take off the sheet, and cool it to room temperature to obtain the open-mixed rubber.

[0038] A4. Vulcanization on a vulcanizer: Put the open-mixed rubber into a vulcanizer for vulcanization, cool it to room temperature for 24 h after exhausting to obtain the product.

[0039] Preferably, the specific conditions of the vulcanization are: vulcanization temperature 140 - 160 °C, vulcanization time 25 - 35 min.

[0040] Applying the new coupling agent for carbon black prepared by the present invention to the preparation of the carbon black reinforced rubber material, the amino group has a strong affinity for carbon black. It can not only form hydrogen bond interactions with the oxygen-containing groups on the surface of carbon black, but also form ionic bonds, greatly improving the dispersion of carbon black and reducing the agglomeration between carbon blacks. At the same time, the structure contains a pyrazine ring that will react with the double bonds in the rubber, enabling better combination of carbon black and rubber and improving multiple properties of the rubber.

[0041] In terms of processing performance, the amino group on the coupling agent has a strong affinity for carbon black. It can not only form hydrogen bond interactions with the oxygen-containing groups on the surface of carbon black, but also form ionic bonds, greatly improving the dispersion of carbon black and reducing the agglomeration between carbon blacks. At the same time, the tetrazine ring contained in the coupling agent structure will react with the double bonds in the rubber, enabling better combination of carbon black and rubber, forming a "carbon black - coupling agent - rubber" bridging structure, weakening the physical crosslinking network formed by direct contact of carbon black, thereby reducing the viscosity of the rubber compound, enhancing the fluidity of the rubber compound, and improving the processing performance.

[0042] In terms of mechanical properties, the coupling agent forms a strong interfacial bond through chemical bonds and physical interactions, enabling the external force to be efficiently transferred from the rubber matrix to the carbon black filler, reducing stress concentration. At the same time, the coupling agent increases the voids between carbon black aggregates, and more rubber molecules penetrate into the voids to form an interpenetrating network structure, increasing the effective load-bearing area. As a result, the carbon black-reinforced rubber material can uniformly bear stress during stretching, significantly improving the tensile strength and modulus at a specified elongation of the carbon black-reinforced rubber material.

[0043] In terms of hysteresis properties, the coupling agent improves the dispersion of carbon black, destroys the rigid network formed by direct filler-filler contact, weakens the Payne effect, reduces energy loss, and thus reduces heat generation and rolling resistance. At the same time, the strong interfacial bond inhibits the relative slip between the rubber molecular chains and the carbon black surface, reducing frictional heat generation. In addition, the enhanced interfacial interaction reduces the slip resistance of the rubber molecular chains on the carbon black surface, reducing hysteresis loss.

[0044] In terms of wear resistance, the bridging structure formed by the addition of the coupling agent can prevent carbon black from detaching from the rubber matrix during the wear process, thereby strengthening the interfacial peel resistance. The uniform dispersion of carbon black reduces local stress concentration, delaying crack initiation and propagation. The amino groups in the coupling agent form a transfer film during the friction process, covering the worn surface. The thermal stability of the tetrazine structure also ensures that the transfer film does not fail under frictional heat generation, enhancing the stability of the friction interface. At the same time, as the dosage of the coupling agent increases, the dispersion and interfacial bonding are gradually optimized, and the wear resistance is improved. However, an excessive amount of the coupling agent may affect other properties of the carbon black-reinforced rubber material.

[0045] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0046] 1. The present invention provides the preparation and application of a novel coupling agent for carbon black. By self-preparing a novel coupling agent for carbon black with amino and tetrazine rings and applying it to carbon black-reinforced rubber materials, it not only has strong affinity with carbon black, greatly improves the dispersion of carbon black, reduces the agglomeration between carbon blacks, but also can react with rubber, enabling better combination of carbon black and rubber, thereby enhancing the various properties of carbon black-reinforced rubber materials and providing broader possibilities for the wide application of carbon black-reinforced rubber materials.

[0047] 2. By selecting 5-amino-2-cyanopyrimidine and hydrazine hydrate as the main reactants, ethanol as the solvent, and insoluble sulfur as the catalyst, the present invention not only simplifies the process but also avoids overreaction or by-product accumulation, thereby improving the yield and purity of the desired coupling agent obtained.

[0048] 3. By selecting the polar protic solvent ethanol as the solvent, the present invention can not only effectively dissolve 5-amino-2-cyanopyrimidine, disperse insoluble sulfur particles at the same time, increase their contact area, but also promote the reaction and reduce the condensation side reaction between amino groups and hydrazine.

[0049] 4. The present invention adopts gradient elution with petroleum ether / ethyl acetate to effectively separate polycyclic products and by-products with small polarity differences, further improving the product purity.

[0050] 5. By applying the prepared carbon black with a novel coupling agent to prepare carbon black-reinforced rubber materials, the amino group has a strong affinity for carbon black. It can not only form hydrogen bonds with oxygen-containing groups on the carbon black surface, but also form ionic bonds, greatly improving the dispersion of carbon black and reducing the agglomeration between carbon blacks. At the same time, the structure contains a pyrazine ring that reacts with double bonds in rubber, enabling better combination of carbon black and rubber and improving multiple properties of rubber. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0052] The raw materials used in the present invention are all commercially available. Specifically:

[0053] The tensile strength of natural rubber is ≥18 MPa, the plasticity retention rate is ≥60%, and the impurity content is ≤0.05%. It is purchased from Shanghai Cunsi Industry Co., Ltd., natural rubber imported from Vietnam.

[0054] Carbon black, the oil absorption value is 120 - 134 10 -5 m3 / kg, the residue on a 325-mesh sieve is ≤0.001%. It is purchased from Tianjin Moke New Material Technology Co., Ltd., carbon black N134, N234.

[0055] Zinc oxide, the average particle size is 25 - 35 nm, and the ignition loss is ≤0.2%. It is purchased from Beijing Decodaojin Technology Co., Ltd., rubber nano-zinc oxide.

[0056] The dropping melting point of the protective wax is 67 - 72 °C, and the kinematic viscosity at 100 °C is 5.0 - 8.5 mm 2 / s. It is purchased from Guangzhou Chuangbo Chemical Co., Ltd., rubber protective wax CB-3.

[0057] Example 1

[0058] This example provides a novel coupling agent for polymer carbon black and its preparation method. The steps are as follows:

[0059] S1. Add 3 mL of absolute ethanol into a round-bottom flask, then add 120 mg (1 mmol) of 5-amino-2-cyanopyrimidine and 64 mg (2.0 mmol) of insoluble sulfur, and then dropwise add 250 mg (5.0 mmol) of hydrazine hydrate. After reacting at 78 °C for 14 h, cool to room temperature, add 8 mL of dichloromethane and 5 mL of deionized water, filter to separate the insoluble sulfur, extract, collect the organic layer, dry with anhydrous CaCl2, and concentrate under reduced pressure to obtain a crude residue oil;

[0060] S2. Elute and purify the crude residue oil on silica gel by flash chromatography to obtain the coupling agent.

[0061] The specific conditions for the elution and purification are as follows: the eluent is petroleum ether / ethyl acetate with a volume ratio of 1:1, 2:1, 4:1 for gradient elution. After collecting the target components and combining them, rotate to evaporate the solvent and then dry under vacuum.

[0062] A carbon black reinforced rubber material, by weight, its preparation raw materials include 100 parts of natural rubber, 50 parts of carbon black, 0.5 part of a new coupling agent for carbon black, 4 parts of zinc oxide, 2 parts of stearic acid, 2 parts of antioxidant 6PPD, 1 part of protective wax, 0.85 part of sulfur, and 1.4 parts of accelerator NS.

[0063] The preparation method of the carbon black reinforced rubber material includes the following steps: add the raw materials into a mixer for mixing, and then mix and vulcanize through a two-roll mill and a vulcanizer to obtain it.

[0064] Preferably, the preparation method of the carbon black reinforced rubber material includes the following steps:

[0065] A1. First-stage mixing: Control the temperature of the mixer at 90 °C and the rotation speed at 90 r / min. Add natural rubber, after mixing for 1 min, add carbon black and the new coupling agent for carbon black, mix for 3 min, then add zinc oxide, stearic acid, antioxidant 6PPD, and protective wax, mix for 2 min, and discharge the rubber at 150 °C to obtain the first-stage mixed rubber;

[0066] A2. Second-stage mixing: Adjust the rotor speed to 60 r / min and the temperature to 90 °C. Add the first-stage mixed rubber and mix for 1 min, then add sulfur and accelerator NS and mix for 1.5 min, and discharge the rubber at 120 °C to obtain the second-stage mixed rubber;

[0067] A3. Mixing on a two-roll mill: Put the second-stage mixed rubber into a two-roll mill, make it wrap around the roll, cut the rubber left and right 2 times, thin pass 6 times, take off the sheet, and cool at room temperature to obtain the mixed rubber on the two-roll mill;

[0068] A4. Vulcanizing with a vulcanizer: Put the mixed rubber on the two-roll mill into a vulcanizer for vulcanization, exhaust, and cool at room temperature for 24 h to obtain it.

[0069] The specific conditions of the vulcanization are: vulcanization temperature is 150° C., and vulcanization time is 30 min.

[0070] Example 2

[0071] The difference between this embodiment and embodiment 1 is that the carbon black reinforced rubber material, in parts by weight, comprises raw materials for preparing the carbon black reinforced rubber material, including 100 parts of natural rubber, 50 parts of carbon black, 1 part of a new coupling agent for carbon black, 4 parts of zinc oxide, 2 parts of stearic acid, 2 parts of antioxidant 6PPD, 1 part of protective wax, 0.85 parts of sulfur, and 1.4 parts of accelerator NS.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the carbon black reinforced rubber material, in parts by weight, is prepared from raw materials including 100 parts of natural rubber, 50 parts of carbon black, 4 parts of zinc oxide, 2 parts of stearic acid, 2 parts of antioxidant 6PPD, 1 part of protective wax, 0.85 parts of sulfur, and 1.4 parts of accelerator NS.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is: S1. Add 3 mL of anhydrous ethanol to a round-bottom flask, then add 120 mg (1 mmol) of 5-amino-2-cyanopyrimidine and 64 mg (2.0 mmol) of insoluble sulfur, and then drop 150 mg (3.0 mmol) of hydrazine hydrate. After reacting at 78° C. for 14 h, cool to room temperature, add 8 mL of dichloromethane and 5 mL of deionized water, filter and separate the insoluble sulfur, collect the organic layer after extraction, dry with anhydrous CaCl2, and concentrate under reduced pressure to obtain a crude residual oil.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is: S1. Add 3 mL of anhydrous ethanol to a round-bottom flask, then add 120 mg (1 mmol) of 5-amino-2-cyanopyrimidine, and then drop 250 mg (5.0 mmol) of hydrazine hydrate. After reacting at 78° C. for 14 h, cool to room temperature, add 8 mL of dichloromethane and 5 mL of deionized water, filter and separate insoluble sulfur, collect the organic layer after extraction, dry with anhydrous CaCl2, and concentrate under reduced pressure to obtain crude residual oil.

[0078] Comparative Example 4

[0079] The differences between this comparative example and Example 1 are as follows: S1. Add 3 mL of N,N-dimethylformamide into a round-bottom flask, then add 120 mg (1 mmol) of 5-amino-2-cyanopyrimidine and 64 mg (2.0 mmol) of insoluble sulfur. Then, dropwise add 250 mg (5.0 mmol) of hydrazine hydrate. After reacting at 78 °C for 14 h, cool to room temperature. Add 8 mL of dichloromethane and 5 mL of deionized water, then filter to separate the insoluble sulfur. After extraction, collect the organic layer, dry it with anhydrous CaCl2, and concentrate it under reduced pressure to obtain a crude residue oil.

[0080] Performance Testing of Carbon Black Reinforced Rubber Materials

[0081] Refer to GB / T 1232.1-2016 to test the fluidity of carbon black reinforced rubber materials. Test conditions: Use a large rotor with a diameter of 38.1 mm, preheat for 1 minute, rotate for 4 minutes, and the test temperature is 100 °C. Use a Shore hardness tester to test the hardness of carbon black reinforced rubber materials. Refer to ISO37-2005 to test the 50% modulus at 100% elongation, 300% modulus at 100% elongation, tensile strength, and elongation at break of carbon black reinforced rubber materials. The test temperature is room temperature, and the tensile rate is 500 mm / min. Refer to GB / T 529-2008 to test the tear strength of carbon black reinforced rubber materials. Refer to GB / T 9867-2008 to test the abrasion resistance of carbon black reinforced rubber materials, and evaluate it by volume loss. Refer to ISO 4666-3:2016 to test the compression heat build-up of carbon black reinforced rubber materials. Refer to ISO4662:2017 to test the rebound resilience of carbon black reinforced rubber materials at 23 °C. Refer to ISO 4664:2021 to test the 60 °C loss factor (tanδ) of carbon black reinforced rubber materials. The results are shown in Table 1.

[0082] Table 1 Test Results

[0083]

[0084]

[0085] By comparing the properties of the carbon black-reinforced rubber materials prepared in Examples 1-2 and Comparative Example 1 in Table 1, it can be seen that for the carbon black-reinforced rubber materials in Examples 1-2 with the coupling agent added, the Mooney viscosity is significantly reduced and the processing performance is improved, indicating that the addition of the LSH coupling agent can weaken the agglomeration of carbon black, and the reduction of the physical crosslinking point density leads to the decrease of the Mooney viscosity of the rubber compound; for the carbon black-reinforced rubber materials in Examples 1-2 with the coupling agent added, the tensile strength and 300% modulus at elongation are both increased to a certain extent, indicating that the addition of the coupling agent increases the aggregation voids between carbon blacks, and more rubber molecules can enter the voids between carbon black aggregates, thereby improving the stress-strain performance of the composite material; from the comprehensive data of compression temperature rise, rebound and DMA 60°C tanδ, it can be seen that the addition of the coupling agent can improve the dynamic heat generation performance of the carbon black-reinforced rubber material, reduce the rolling resistance, and significantly improve the low hysteresis performance of the carbon black-reinforced rubber material, indicating that the addition of the coupling agent can improve the interfacial interaction between carbon black and rubber, weaken the Payne effect, and thus reduce heat generation and rolling resistance; from the DIN wear volume data, it can be seen that the addition of the coupling agent can significantly improve the wear resistance of the carbon black-reinforced rubber material, and the wear resistance becomes better with the increase of the coupling agent dosage.

[0086] By comparing Example 1 with Comparative Examples 2-4, the effects of the preparation raw materials and process of the coupling agent on the carbon black-reinforced rubber material were analyzed. In Comparative Example 2, too little hydrazine hydrate was added, which might lead to incomplete cyclization, the product containing uncondensed intermediates, low purity, and affecting the carbon black dispersion and the properties of the rubber material; in Comparative Example 3, without the insoluble sulfur catalyst, the reaction rate would be significantly reduced, the proportion of tetrazine rings in the product would decrease, the yield would decrease, and the by-products would increase, thus reducing the carbon black dispersion and the properties of the rubber material; in Comparative Example 4, the solvent was changed to the strongly polar aprotic solvent N,N-dimethylformamide with a relatively high boiling point, and side reactions such as amino oxidation might occur during the removal of the solvent at high temperature, so the product purity would be affected, and further the carbon black dispersion and the properties of the rubber material would be affected.

[0087] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A novel coupling agent for carbon black, characterized in that, Its chemical structural formula is shown in the following formula: The preparation method of the novel coupling agent for carbon black includes the following steps: S1. Add a solvent, reaction raw materials and a catalyst into a round-bottom flask, react at 78 °C for 12 - 16 h, then cool to room temperature, add dichloromethane and deionized water, filter, extract, collect the organic layer, dry with anhydrous CaCl2, and concentrate under reduced pressure to obtain a crude residue oil; S2. Elute and purify the crude residue oil on silica gel by flash chromatography to obtain the coupling agent.

2. Preparation of the novel coupling agent for carbon black according to claim 1, characterized in that, The reaction raw materials are 5-amino-2-cyanopyrimidine and hydrazine hydrate, and the molar ratio is 1:(4.5 - 5.5).

3. Preparation of the novel coupling agent for carbon black according to claim 2, characterized in that, The catalyst is insoluble sulfur; the molar ratio of the reaction raw materials to the catalyst is (2 - 4):

1.

4. The preparation of the novel coupling agent for carbon black according to claim 1, characterized in that, The solvent is anhydrous ethanol.

5. The preparation of the novel coupling agent for carbon black according to claim 2, characterized in that, The solid-liquid ratio of the solvent to the reaction raw materials is 1 mL:(140 - 150) mg.

6. The preparation of the novel coupling agent for carbon black according to claim 5, characterized in that, The addition amounts of dichloromethane and water are 2 - 3 times and 1 - 2 times the volume of the solvent, respectively.

7. The preparation of the novel coupling agent for carbon black according to claim 1, characterized in that, The specific conditions for the elution and purification are as follows: the eluent is petroleum ether / ethyl acetate, elute at a gradient of volume ratios of 1:1, 2:1, and 4:1, collect and combine the target components, remove the solvent by rotary evaporation, and then dry under vacuum.

8. Use of the novel coupling agent for carbon black according to any one of claims 1 to 7, characterized in that, It is applied to carbon black-reinforced rubber materials.

9. Use of the novel coupling agent for carbon black according to claim 8, characterized in that, The carbon black-reinforced rubber material, by weight, its preparation raw materials include 100 parts of natural rubber, 45 - 55 parts of carbon black, 0.1 - 2 parts of the novel coupling agent for carbon black, 3 - 5 parts of zinc oxide, 1 - 3 parts of stearic acid, 1 - 3 parts of antioxidant, 0.5 - 2 parts of protective wax, 0.5 - 1 part of sulfur, and 1 - 2 parts of accelerator.

10. The application of the novel coupling agent for carbon black according to claim 9, characterized in that, The preparation method of the carbon black-reinforced rubber material includes the following steps: add the raw materials into a mixer for mixing, and then mix and vulcanize through an open mill and a vulcanizer to obtain the product.

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