Azo silane coupling agent, synthesis method and application thereof

Abstract

This invention discloses an azo silane coupling agent, its synthesis method, and applications. This azo silane coupling agent, derived from a substitution reaction between chloropropyltriethoxysilane and azodicarbonamide, improves the dispersibility of silica in natural rubber, thereby enhancing the mechanical properties and processing stability of the rubber compound. Compared to the commonly used silane coupling agent Si75 (bis-(triethoxysilylpropyl) disulfide), this product exhibits a better dispersion of silica in rubber compounds, improving the rubber compound's wear resistance and reducing its rolling resistance.

Description

Technical Field

[0001] The invention relates to an azo silane coupling agent, and also relates to a synthesis method and application of the azo silane coupling agent, belonging to the technical field of chemical synthesis. Background Art

[0002] Azo silane coupling agents are a new type of rubber silane used in the tire industry. They are used as coupling agents in silica-reinforced rubber compounds, particularly in fuel-efficient tires. Due to their low sulfur content in their molecular structure, they are less susceptible to scorching and safer to process. Research has shown that silica modified with azo silane coupling agents exhibits better wear resistance and lower rolling resistance than silica modified with the coupling agent Si75 (bis-(triethoxysilylpropyl) disulfide).

[0003] Currently, there are few reports on the synthesis and application of azo silane coupling agents. Summary of the Invention

[0004] The present invention aims to provide an azo silane coupling agent, which is obtained by reacting an azo compound and a silane coupling agent. The azo silane coupling agent has a better effect of improving the dispersibility of white carbon black in a rubber compound than a silane coupling agent, and the rubber compound has better wear resistance and lower rolling resistance.

[0005] The azo silane coupling agent of the present invention has the following structural formula:

[0006]

[0007] The azo silane coupling agent is obtained by a substitution reaction between chloropropyltriethoxysilane and azodicarbonamide. The synthesis method specifically includes the following steps:

[0008] Using chloropropyltriethoxysilane and azodicarbonamide as raw materials, triethylamine as solvent and acid binding agent, an azo silane coupling agent is obtained through substitution reaction. The reaction formula is as follows:

[0009]

[0010] Furthermore, the molecular formula of the azodicarbonamide is C2H4N4O2, and the molar ratio of chloropropyltriethoxysilane to azodicarbonamide is 1:0.5-1, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, preferably 1:0.7-1.

[0011] Furthermore, the molar ratio of chloropropyltriethoxysilane to triethylamine is 1:1-1.3, for example, 1:1, 1:1.1, 1:1.2, 1:1.3.

[0012] Furthermore, chloropropyltriethoxysilane, azodicarbonamide and triethylamine are mixed and then heated to react. There is no special requirement for the mixing order of the three.

[0013] Furthermore, the present invention adopts a two-stage heating method to carry out the reaction, wherein the mixture of chloropropyltriethoxysilane, azodicarbonamide and triethylamine is first heated to 90-95° C. for reflux reaction for 2-3 hours, and then heated to 120-125° C. for reaction for 4-5 hours.

[0014] Furthermore, after the reaction is completed, the reaction liquid is post-treated to obtain an azo silane coupling agent product. The post-treatment process includes: cooling the reaction liquid to room temperature, filtering to remove the formed triethylamine hydrochloride and unreacted azodicarbonamide, and then distilling the filtrate or distilling under reduced pressure to remove the triethylamine. The residue is the final product.

[0015] The present invention also provides the use of the azo silane coupling agent as a white carbon black dispersant.

[0016] The present invention has the following beneficial effects:

[0017] 1. This invention uses triethoxychloropropylsilane and azodicarbonamide as raw materials, resulting in an azo silane coupling agent through a substitution reaction. This product improves the dispersibility of silica in natural rubber, thereby enhancing the mechanical properties and processing stability of the rubber compound. Compared with the commonly used silane coupling agent Si75 [bis-(triethoxysilylpropyl) disulfide], this product exhibits better dispersion of silica in rubber compounds, improving the rubber compound's wear resistance and reducing its rolling resistance.

[0018] 2. The synthesis method of the present invention is simple and easy to operate. Triethylamine is used as both a solvent and an acid-binding agent, which improves the efficiency and yield of the reaction. The reaction adopts a two-stage temperature increase operation, which improves the reaction efficiency and improves the yield and purity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a high performance liquid chromatogram of the product obtained in Example 4 of the present invention.

[0020] Figure 2 This is the H NMR spectrum of the product obtained in Example 4 of the present invention. DETAILED DESCRIPTION

[0021] The following description of exemplary embodiments of the present invention includes various details to facilitate understanding, which should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions, operations, and structures are omitted from the following description.

[0022] In the following examples and comparative examples, the yield is calculated as follows: yield = mass of the obtained product / (0.5 × molar amount of chloropropyltriethoxysilane × molecular weight of the azo silane coupling agent) × 100%.

[0023] Example 1

[0024] 238.4 g (1 mol) of chloropropyltriethoxysilane, 101.19 g of triethylamine (1 mol), and 58.04 g of azodicarbonamide (0.5 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. Triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser tube. 6.8 g of fraction was obtained, which was 98.7% triethylamine as determined by gas chromatography. The remainder was the azo silane coupling agent product, totaling 152.04 g. The product appeared as a red oily liquid, and the purity was 84.68% as determined by liquid chromatography.

[0025] Example 2

[0026] In a three-necked flask, 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 58.04 g of azodicarbonamide (0.5 mol) were added. The temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser. 14.3 g of fraction was obtained; 157.27 g of azo silane coupling agent product was obtained; the product was a red oily liquid, and the purity was 84.42% as determined by liquid chromatography.

[0027] Example 3

[0028] 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 69.65 g of azodicarbonamide (0.6 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser, and 166.54 g of azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 85.33%.

[0029] Example 4

[0030] 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 87.06 g of azodicarbonamide (0.75 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser, and 190.13 g of azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 85.79%. Figure 1 HPLC chart of the obtained product. Figure 2 The NMR spectrum of the obtained product.

[0031] Example 5

[0032] 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 116.08 g of azodicarbonamide (1 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser, and 188.02 g of azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 85.06%.

[0033] Example 6

[0034] 238.4 g (1 mol) of chloropropyltriethoxysilane, 122.44 g of triethylamine (1.21 mol), and 116.08 g of azodicarbonamide (1 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After 2 hours, the temperature was raised to 120-125°C, kept warm for 4 hours, and then cooled to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser tube, and 184.27 g of azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 85.50%.

[0035] Comparative Example 1

[0036] 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 116.08 g of azodicarbonamide (1 mol) were added to a three-necked flask, and the temperature was raised to 90-95°C to start reflux reaction. After keeping the temperature for 6 hours, the temperature was lowered to room temperature, and the triethylamine hydrochloride and unreacted azodicarbonamide were filtered out. The filtrate was subjected to vacuum distillation at a pressure of -0.08-0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser tube, and 170.97 g of azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 83.51%.

[0037] Comparative Example 2

[0038] 238.4 g (1 mol) of chloropropyltriethoxysilane, 111.31 g of triethylamine (1.1 mol), and 116.08 g of azodicarbonamide (1 mol) were added to a three-necked flask, and the temperature was raised to 50°C to start the reaction. After the reaction was kept at this temperature for 8 hours, the temperature was lowered to room temperature. The triethylamine hydrochloride and unreacted azodicarbonamide were filtered out, and the filtrate was subjected to negative pressure distillation at a pressure of -0.08 to -0.09 MPa and a temperature of 110°C. The distillation was considered complete when no fraction appeared on the condenser tube, and 207.49 g of an azo silane coupling agent product was obtained. The product was tested by liquid chromatography and the purity was 3.24%.

Claims

1. A method for synthesizing an azo silane coupling agent, characterized in that: The azo silane coupling agent has the structural formula shown below: The synthesis method comprises: adding 238.4 g of chloropropyltriethoxysilane, 111.31 g of triethylamine, and 87.06 g of azodicarbonamide into a three-necked flask, heating the mixture to 90-95° C. to start a reflux reaction, heating the mixture to 120-125° C. after 2 hours, keeping the temperature for 4 hours, and then cooling the mixture to room temperature, filtering the triethylamine hydrochloride and unreacted azodicarbonamide, and performing vacuum distillation on the filtrate at a pressure of -0.08-0.09 MPa and a temperature of 110° C. The distillation is considered complete when no fraction appears on the condenser, thereby obtaining an azo silane coupling agent product.

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