Rubber accelerator 2-mercaptobenzothiazole tellurium and its preparation method and application

Abstract

The application discloses a rubber accelerator 2-mercaptobenzothiazole tellurium and a preparation method and application thereof. The 2-mercaptobenzothiazole and the tellurium dioxide are respectively dissolved in solvents to obtain a tellurium dioxide solution and a 2-mercaptobenzothiazole solution; the tellurium dioxide solution is dropped into the 2-mercaptobenzothiazole solution, and a rubber accelerator 2-mercaptobenzothiazole tellurium is obtained by reaction under stirring. The preparation method is simple in operation, has few side reactions and can be carried out at room temperature. The rubber accelerator 2-mercaptobenzothiazole tellurium prepared has a medium speed and is superior to existing thiazole accelerators (M and DM) and selenothiazole accelerators (SeM) in performance.

Description

Technical Field

[0001] This invention relates to the field of rubber accelerator technology, specifically to a rubber accelerator 2-mercaptobenzothiazole tellurium, its preparation method, and its application. Background Technology

[0002] Vulcanization is a chemical change process in which raw rubber undergoes intermolecular cross-linking, transforming linear macromolecular chains into a three-dimensional network structure. During this process, the physical properties of the rubber compound also undergo fundamental changes. Vulcanized rubber exhibits characteristics such as reduced stickiness, higher elasticity, better heat resistance, higher tensile strength, insolubility in organic solvents, and resistance to breakage. It is commonly referred to as cured rubber or rubber sheet, and most rubber products are made from vulcanized rubber. Vulcanization is usually the final step in rubber processing.

[0003] Sulfur vulcanization has the longest history, and the raw materials used are inexpensive and abundant. The sulfur vulcanization system with accelerators is the most widely used vulcanization system. The use of accelerators greatly shortens the vulcanization time, lowers the vulcanization temperature, reduces the amount of sulfur used, and also significantly improves the physical and mechanical properties of rubber.

[0004] In 1925, Sebrell and Bruni discovered that 2-mercaptobenzothiazole (accelerator M) and its homologue dibenzothiazole disulfide (accelerator DM) had excellent vulcanization accelerator effects, and the vulcanizates prepared from them exhibited good mechanical properties. In the rubber industry, thiazole accelerators are commonly used general-purpose vulcanization accelerators, widely applied to various types of rubber. Due to the presence of the CS accelerator group in their molecular structure, they belong to the near-rate vulcanization accelerator category and are mainly used in large components such as tires and rubber belts.

[0005] A method for synthesizing selenobenzothiazole was published in (South China University of Technology. A rubber accelerator, selenobenzothiazole, its preparation method and application: CN202010899664.1[P]. 2020-11-17.). It has a moderate vulcanization rate and belongs to the medium-speed accelerator category.

[0006] Thiazole accelerators are inexpensive and widely used, but they have low vulcanization efficiency and require large quantities, which needs further improvement. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a rubber accelerator 2-mercaptobenzothiazole tellurium, its preparation method, and its application. The accelerator 2-mercaptobenzothiazole tellurium prepared by this method is a medium-speed accelerator.

[0008] The objective of this invention is achieved through at least one of the following technical solutions.

[0009] A method for preparing a rubber accelerator, 2-mercaptobenzothiazole tellurium, includes the following steps:

[0010] 2-Mercaptobenzothiazole and tellurium dioxide were dissolved in solvents to obtain tellurium dioxide solution and 2-mercaptobenzothiazole solution, respectively. The tellurium dioxide solution was added dropwise to the 2-mercaptobenzothiazole solution and reacted under stirring to obtain the rubber accelerator 2-mercaptobenzothiazole tellurium.

[0011] Preferably, the solvent is one or more of anhydrous ethanol, dichloromethane, acetone, and dilute hydrochloric acid.

[0012] More preferably, the concentration of the dilute hydrochloric acid is 10-14 mol / L.

[0013] Preferably, the 2-mercaptobenzothiazole and tellurium dioxide are dissolved in solvents and stirred.

[0014] More preferably, the stirring rate of the stirring conditions is 200 rpm to 300 rpm.

[0015] Preferably, the concentration of the tellurium dioxide solution is 0.016~0.107 g / mL;

[0016] Preferably, the concentration of the 2-mercaptobenzothiazole solution is 0.045~0.053 g / mL.

[0017] Preferably, the molar ratio of tellurium dioxide to 2-mercaptobenzothiazole is 1:3.5~5.

[0018] Preferably, the tellurium dioxide is industrial-grade tellurium dioxide with a purity of 99%; and the 2-mercaptobenzothiazole is commercially available 2-mercaptobenzothiazole with a purity of 98%.

[0019] Preferably, the tellurium dioxide solution is added dropwise to the 2-mercaptobenzothiazole solution at a rate of one drop per second.

[0020] Preferably, the reaction temperature is 4℃-50℃;

[0021] Preferably, the reaction time is 2 to 3 hours;

[0022] Preferably, the stirring rate during the stirring state is 200 rpm to 300 rpm.

[0023] Preferably, after the reaction, the mixture is filtered, the filter residue is collected, washed, dried, crushed, and sieved.

[0024] A further preferred method is hot filtration.

[0025] This invention provides a rubber accelerator, 2-mercaptobenzothiazole tellurium, prepared by the above-described method. Its melting point is 156-159°C, its decomposition temperature is 257-259°C, and its product yield is 85%-95%.

[0026] This invention provides the application of the above-mentioned rubber accelerator 2-mercaptobenzothiazole tellurium in the preparation of vulcanized rubber.

[0027] The rubber accelerator 2-mercaptobenzothiazole tellurium provided by this invention has better performance than the near-rate accelerators M and DM, and is also better than seleno-2-mercaptobenzothiazole. Compared with the prior art, this invention has the following advantages and beneficial effects.

[0028] (1) The synthesis process used in this invention is a "one-pot method", which does not require a reaction temperature and can react rapidly at room temperature. It is simple to operate and has few side reactions.

[0029] (2) The reaction product of the present invention is an insoluble powder, which is easy to purify and does not require organic solvents, thus reducing the generation of wastewater.

[0030] (3) This invention expands the application scope of benzothiazole, and the performance of 2-mercaptobenzothiazole tellurium is better than that of existing thiazole accelerators (M, DM) and selenothiazole accelerators (SeM). Attached Figure Description

[0031] Figure 1 The vulcanization curves are for the compound rubbers prepared in Examples 4-6, where SBR / TeM represents the compound rubber.

[0032] Figure 2 The vulcanization curves are for the compound rubbers prepared in Example 4 and Comparative Examples 1-3.

[0033] Figure 3 The graph shows the tensile strength retention rate of the rubber compounds in Examples 7-10 after aging.

[0034] Figure 4 The graph shows the elongation at break retention rate of the rubber compounds in Examples 7-10 after aging.

[0035] Figure 5 The infrared spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1 is shown.

[0036] Figure 6 The image shows the DSC thermal analysis spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1.

[0037] Figure 7 The image shows the TG thermal analysis spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1. Detailed Implementation Plan

[0038] The following examples further illustrate specific implementations of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0039] The styrene-butadiene rubber and sulfur masterbatch described in the following examples were purchased from Dongguan Siqi Rubber Technology Co., Ltd., and the open mill was a small 6-inch experimental rubber mixing mill manufactured by Guangdong Lina Industrial Co., Ltd.

[0040] Example 1

[0041] 3.2 g (0.02 mol) of tellurium dioxide was dissolved in 30 ml of hydrochloric acid (12 mol / L) under stirring at 300 rpm. 13.5 g (0.081 mol) of 2-mercaptobenzothiazole was dissolved in 300 ml of anhydrous ethanol under stirring at 300 rpm. The tellurium dioxide solution was added dropwise to the 2-mercaptobenzothiazole solution at a rate of 1 drop per second. The reaction temperature was controlled at 30 °C, and the stirring rate at 300 rpm. After reacting for 2 hours, the mixture was filtered while hot, and the residue was washed, dried, and pulverized to obtain the rubber accelerator 2-mercaptobenzothiazole tellurium. The yield of the obtained product was 89.3% (based on tellurium dioxide), the melting point of the product was 159 °C, and the decomposition temperature was 257 °C.

[0042] Example 2

[0043] 3.2 g (0.02 mol) of tellurium dioxide was dissolved in 200 ml of anhydrous ethanol under stirring at 300 rpm. 15 g (0.09 mol) of 2-mercaptobenzothiazole was also dissolved in 300 ml of anhydrous ethanol under stirring at 300 rpm. The tellurium dioxide solution was added dropwise to the 2-mercaptobenzothiazole solution at a rate of 1 drop per second. The reaction temperature was controlled at 8 °C, and the stirring rate at 200 rpm. After reacting at this temperature for 3 hours, the mixture was filtered while hot, and the residue was washed, dried, and pulverized to obtain the rubber accelerator 2-mercaptobenzothiazole tellurium. The yield of the obtained product was 92.1% (based on tellurium dioxide), the melting point of the product was 156 °C, and the decomposition temperature was 257 °C.

[0044] Example 3

[0045] 3.2 g (0.02 mol) of tellurium dioxide was dissolved in 50 ml of acetone under stirring at 300 rpm. 16 g (0.096 mol) of 2-mercaptobenzothiazole was dissolved in 300 ml of anhydrous ethanol under stirring at 300 rpm. The tellurium dioxide solution was added dropwise to the 2-mercaptobenzothiazole solution at a rate of 1 drop per second. The reaction temperature was controlled at 4 °C, and the stirring rate at 300 rpm. After reacting at this temperature for 3 hours, the mixture was filtered while hot, and the residue was washed, dried, and pulverized to obtain the rubber accelerator 2-mercaptobenzothiazole tellurium. The yield of the obtained product was 90.4% (based on tellurium dioxide), the melting point of the product was 159 °C, and the decomposition temperature was 259 °C.

[0046] Example 4

[0047] 2.5g of sulfur masterbatch (80% sulfur content), 1g of 2-mercaptobenzothiazole telluride (prepared from Example 1), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170°C to obtain a compound denoted as SBR / TeM. Its vulcanization curve is shown below. Figure 1 As shown in Table 1, its vulcanization parameters are as follows.

[0048] Example 5

[0049] 2.5g of sulfur masterbatch (80% sulfur content), 1g of 2-mercaptobenzothiazole telluride (prepared from Example 2), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170°C to obtain a compound rubber. The vulcanization curve is shown below. Figure 1 As shown.

[0050] Example 6

[0051] 2.5g of sulfur masterbatch (80% sulfur content), 1g of 2-mercaptobenzothiazole telluride (prepared from Example 3), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170°C to obtain a compound rubber, the vulcanization curve of which is shown below. Figure 1 As shown.

[0052] The vulcanization characteristics of SBR compound materials were tested at 170℃ using a Taiwan U-Can UR-2030 dynamic mold rheometer.

[0053] Figure 1 The vulcanization curves of the vulcanizates obtained in Examples 4-6 are shown below. Figure 1 It can be concluded that the vulcanization curves of the rubber compounds obtained in Examples 4, 5, and 6 are basically the same, and the scorch time, vulcanization time, and maximum torque are basically the same. Therefore, the rubber compound of Example 4 is selected for comparison and explanation.

[0054] Example 7

[0055] 50 phr carbon black, 2.5 g sulfur masterbatch (80% sulfur content), 1 g 2-mercaptobenzothiazole telluride (prepared from Example 1), 5 g zinc oxide, and 1 g stearic acid were added to 100 g styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170°C to obtain a compound rubber, denoted as SBR / N550 / TeM. Its resistance to thermo-oxidative aging is as follows: Figure 3 and Figure 4 As shown.

[0056] Example 8

[0057] 50 phr carbon black, 2.5 g sulfur masterbatch (80% sulfur content), 1 g 2-mercaptobenzothiazole (accelerator M), 5 g zinc oxide, and 1 g stearic acid were added to 100 g styrene-butadiene rubber using an open mill. The mixture was vulcanized at 170°C to obtain a compound rubber, denoted as SBR / N550 / M. Its resistance to thermo-oxidative aging is as follows: Figure 3 and Figure 4 As shown.

[0058] Example 9

[0059] 50 phr carbon black, 2.5 g sulfur masterbatch (80% sulfur content), 1 g 2-mercaptobenzothiazole (accelerator DM), 5 g zinc oxide, and 1 g stearic acid were added to 100 g styrene-butadiene rubber using an open mill. The mixture was vulcanized at 170°C to obtain a compound rubber, denoted as SBR / N550 / DM. Its resistance to thermo-oxidative aging is as follows: Figure 3 and Figure 4 As shown.

[0060] Example 10

[0061] 50 phr carbon black, 2.5 g sulfur masterbatch (80% sulfur content), selenobenzothiazole (accelerator SeM), 5 g zinc oxide, and 1 g stearic acid were added to 100 g styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170°C to obtain a compound rubber, denoted as SBR / N550 / SeM. Its resistance to thermo-oxidative aging is as follows: Figure 3 and Figure 4 As shown.

[0062] Comparative Example 1

[0063] 2.5g of sulfur masterbatch (80% sulfur content), 1g of 2-mercaptobenzothiazole (accelerator M), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was vulcanized at 170℃ to obtain a compound denoted as SBR / M. Its vulcanization curve is shown below. Figure 2 As shown, its vulcanization parameters are shown in Table 1.

[0064] Comparative Example 2

[0065] 2.5g of sulfur masterbatch (80% sulfur content), 1g of dibenzothiazole disulfide (accelerator DM), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was then vulcanized at 170℃ to obtain a compound, denoted as SBR / DM. Its vulcanization curve is shown below. Figure 2 As shown, its vulcanization parameters are shown in Table 1.

[0066] Comparative Example 3

[0067] 2.5g of sulfur masterbatch (80% sulfur content), 1g of selenobenzothiazole (accelerator SeM), 5g of zinc oxide, and 1g of stearic acid were added to 100g of styrene-butadiene rubber using an open mill. The mixture was vulcanized at 170℃ to obtain a compound, denoted as SBR / SeM. Its vulcanization curve is shown below. Figure 2 As shown, its vulcanization parameters are shown in Table 1.

[0068] The vulcanization parameters of the rubber compounds obtained in Examples 4 and Comparative Examples 1-3 are shown in Table 1, and the vulcanization curves of the rubber compounds obtained in Examples 4 and Comparative Examples 1-3 are shown in Table 1. Figure 2 From Table 1 and Figure 2 It can be seen that among the four accelerators, 2-mercaptobenzothiazole tellurium compound (SBR / TeM) has the fastest vulcanization speed and the largest torque, indicating the highest vulcanization efficiency.

[0069] Table 1 shows the vulcanization parameters of the compound rubbers prepared in Example 4 and Comparative Examples 1-3.

[0070]

[0071] The physical properties of the compound rubbers prepared in Example 4 and Comparative Examples 1-3 are shown in Table 2. Table 2 shows that the physical properties of the 2-mercaptobenzothiazole telluride vulcanizate are enhanced compared to the other two. Specifically, the tensile strength increases by 32.7% compared to SBR / M, 62% compared to SBR / DM, and 13% compared to SBR / SeM; the 100% elongation increases by 14.3% compared to SBR / M, 11.4% compared to SBR / DM, and 8% compared to SBR / SeM; and the 300% elongation increases by 24.3% compared to SBR / M, 55% compared to SBR / DM, and 8% compared to SBR / SeM.

[0072] Table 2. Physical property parameters of the rubber compounds obtained in Example 4 and Comparative Examples 1-3

[0073]

[0074] The thermo-oxidative aging resistance of the compound rubber prepared in Examples 7-10 is as follows: Figure 3 and Figure 4As shown in the figure, after the same aging time, SBR / N550 / TeM has the highest tensile strength retention rate and elongation at break retention rate. The tensile strength retention rate is about 10% higher than the other three accelerators, and the elongation at break retention rate is about 8% higher than the other three accelerators.

[0075] The infrared spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1 of this invention is as follows: Figure 5 As shown in the figure, it can be seen that: 3056 is the absorption peak of CH, 1490 is the absorption peak of C=C, 1594 is the absorption peak of C=N, and 666 is the absorption peak of CS. The absence of SH and NH peaks in the spectrum indicates that the synthesized substance is different from M.

[0076] The infrared spectra of the 2-mercaptobenzothiazole tellurium prepared in other embodiments were similar to those in Example 1.

[0077] Elemental analysis revealed the elemental contents of C, H, S, and N, allowing for the deduction of possible chemical structures. Table 3 shows the elemental analysis of 2-mercaptobenzothiazole tellurium prepared in Example 1. The actual values ​​match the theoretical values, demonstrating the successful synthesis of 2-mercaptobenzothiazole tellurium.

[0078] Table 32 Elemental Analysis of 2-Mercaptobenzothiazole Tellurium

[0079]

[0080] The DSC thermal analysis curve of 2-mercaptobenzothiazole tellurium prepared in Example 1 of this invention is shown below. Figure 6 As shown, its TG thermal analysis curve is as follows: Figure 7 As shown. From Figure 6 and Figure 7 It can be seen that the product has a melting point of 159℃, a decomposition temperature of 257℃, and only one thermal weight loss step, indicating that the product has a high purity.

[0081] The above embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. The application of a rubber accelerator, 2-mercaptobenzothiazole tellurium, in the preparation of vulcanized rubber, characterized in that, The preparation method of the rubber accelerator 2-mercaptobenzothiazole tellurium includes the following steps: 2-Mercaptobenzothiazole and tellurium dioxide are dissolved separately in a solvent to obtain a tellurium dioxide solution and a 2-mercaptobenzothiazole solution. The tellurium dioxide solution is added dropwise to the 2-mercaptobenzothiazole solution, and the reaction is carried out under stirring to obtain the rubber accelerator 2-mercaptobenzothiazole tellurium. The solvent is one or more of anhydrous ethanol, dichloromethane, acetone, and dilute hydrochloric acid. The molar ratio of tellurium dioxide to 2-mercaptobenzothiazole is 1:3.5~5. The tellurium dioxide solution is added dropwise to the 2-mercaptobenzothiazole solution at a rate of dropwise per second. The reaction temperature is 4℃-50℃, the reaction time is 2~3 hours, and the stirring speed is 200rpm-300rpm.

2. The application of the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1 in the preparation of vulcanized rubber, characterized in that, The 2-mercaptobenzothiazole and tellurium dioxide were dissolved in a solvent and stirred under stirring conditions; the stirring rate of the stirring conditions was 200 rpm-300 rpm.

3. The application of the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1 in the preparation of vulcanized rubber, characterized in that, The concentration of the tellurium dioxide solution is 0.016~0.107 g / mL; The concentration of the 2-mercaptobenzothiazole solution is 0.045~0.053 g / mL.

4. The application of the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1 in the preparation of vulcanized rubber, characterized in that, After the reaction, the mixture is filtered, the filter residue is collected, washed, dried, crushed, and sieved.

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