Rubber accelerator 2-mercaptobenzothiazole tellurium as well as preparation method and application thereof

Abstract

The invention discloses a rubber accelerator 2-mercaptobenzothiazole tellurium as well as a preparation method and application thereof. The preparation method comprises the following steps: respectively dissolving 2-mercaptobenzothiazole and tellurium dioxide in a solvent to obtain a tellurium dioxide solution and a 2-mercaptobenzothiazole solution; and dropwise adding the tellurium dioxide solution into the 2-mercaptobenzothiazole solution, and reacting in a stirring state to obtain the rubber accelerator tellurium 2-mercaptobenzothiazole. The preparation method disclosed by the invention is simple to operate and few in side reaction, and can be carried out at room temperature; the prepared rubber accelerator 2-mercaptobenzothiazole tellurium belongs to a medium-speed accelerator, and the performance of the rubber accelerator 2-mercaptobenzothiazole tellurium is superior to that of the existing thiazole accelerator (M, DM) and selenothiazole accelerator (SeM).

Description

Technical Field

[0001] The invention relates to the technical field of rubber accelerators, and in particular to a rubber accelerator 2-mercaptobenzothiazole tellurium and a preparation method and application thereof. Background Art

[0002] Vulcanization is a chemical change process in which the raw rubber is cross-linked between molecules and the linear macromolecular chains are chemically cross-linked to form a spatial network structure. In this process, the physical properties of the rubber compound also undergo fundamental changes. The vulcanized rubber has the characteristics of no viscosity, high elasticity, good heat resistance, high tensile strength, insolubility in organic solvents, and not easy to break. We usually call it cooked rubber or rubber skin. Most rubber products are vulcanized rubber. Usually vulcanization is the last step in the rubber processing process.

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

[0004] In 1925, Sebrell and Bruni found that 2-mercaptobenzothiazole (accelerator M) and its homologue dibenzothiazole disulfide (accelerator DM) have good vulcanization accelerating effects, and the prepared vulcanized rubber has good mechanical properties. In the rubber industry, thiazole accelerators are commonly used general-purpose vulcanization accelerators and are widely used in various types of rubber. Due to the CS promoting group in its molecular structure, it is a quasi-speed vulcanization accelerator and is mainly used in large-scale products such as tires and belts.

[0005] A method for synthesizing selenobenzothiazole was disclosed in (South China University of Technology. A rubber accelerator selenobenzothiazole and its preparation method and application: CN202010899664.1[P].2020-11-17.), which has a medium vulcanization rate and is a medium-speed accelerator.

[0006] Thiazole accelerators are cheap and widely used, but their vulcanization efficiency is low and their usage is large, which needs further improvement. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a rubber accelerator 2-mercaptobenzothiazole tellurium and a preparation method and application thereof. The accelerator 2-mercaptobenzothiazole tellurium prepared by the method is a medium-speed accelerator.

[0008] The purpose of the present invention is achieved by at least one of the following technical solutions.

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

[0010] 2-mercaptobenzothiazole and tellurium dioxide are dissolved in solvents respectively to obtain tellurium dioxide solution and 2-mercaptobenzothiazole solution; the tellurium dioxide solution is dropped into the 2-mercaptobenzothiazole solution, and the mixture is reacted under stirring to obtain rubber accelerator 2-mercaptobenzothiazole tellurium.

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

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

[0013] Preferably, the 2-mercaptobenzothiazole and tellurium dioxide are dissolved in a solvent respectively and the reaction is carried out under stirring;

[0014] Further preferably, the stirring rate of the stirring condition is 200 rpm-300 rpm.

[0015] Preferably, the concentration of the tellurium dioxide solution is 0.016 to 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 source of the tellurium dioxide is industrial-grade tellurium dioxide with a purity of 99%; the source of the 2-mercaptobenzothiazole is commercially available 2-mercaptobenzothiazole with a purity of 98%.

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

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

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

[0022] Preferably, the stirring rate in the stirring state is 200 rpm-300 rpm.

[0023] Preferably, after the reaction, suction filtration is performed, and the filter residue is taken, washed, dried, crushed, and sieved.

[0024] More preferably, the suction filtration is performed while hot.

[0025] The present invention provides a rubber accelerator 2-mercaptobenzothiazole tellurium prepared by the above preparation method, which has a melting point of 156-159° C., a decomposition temperature of 257-259° C., and a product yield of 85%-95%.

[0026] The present invention provides an application of the rubber accelerator 2-mercaptobenzothiazole tellurium in the preparation of vulcanized rubber.

[0027] The performance of the rubber accelerator 2-mercaptobenzothiazole tellurium provided by the present invention is better than that of the quasi-speed grade accelerators M and DM, and is better than that of seleno-2-mercaptobenzothiazole. Compared with the prior art, the present invention has the following advantages and beneficial effects.

[0028] (1) The synthesis process adopted by the present invention is a "one-pot method", which has no requirements on the reaction temperature, can react quickly at room temperature, 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 an organic solvent, thereby reducing the generation of waste water.

[0030] (3) The present invention expands the application scope of benzothiazole, and the performance of 2-mercaptobenzothiazole tellurium is better than the existing thiazole accelerators (M, DM) and selenothiazole accelerators (SeM). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The vulcanization curves of the rubber mixes prepared in Examples 4-6, wherein SBR / TeM represents the rubber mix.

[0032] Figure 2 The vulcanization curves of the rubber compounds obtained in Example 4 and Comparative Examples 1-3 are shown.

[0033] Figure 3 This is a graph showing the tensile strength retention of the rubber compounds of Examples 7 to 10 after aging.

[0034] Figure 4 This is a graph showing the elongation at break retention rate of the rubber compounds of Examples 7 to 10 after aging.

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

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

[0037] Figure 7 This is the TG thermal analysis spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1. Specific implementation plan

[0038] The specific implementation of the present invention is further described below in conjunction with examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed 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 mixing mill was a small 6-inch experimental mixing mill produced by Guangdong Lina Industrial Co., Ltd.

[0040] Example 1

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

[0042] Example 2

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

[0044] Example 3

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

[0046] Example 4

[0047] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of 2-mercaptobenzothiazole tellurium (prepared in Example 1), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber by an open mill, and vulcanized at 170° C. to obtain a mixed rubber, which was recorded as SBR / TeM. Its vulcanization curve is as follows: Figure 1 The vulcanization parameters are shown in Table 1.

[0048] Example 5

[0049] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of 2-mercaptobenzothiazole tellurium (prepared in Example 2), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber by an open mill, and vulcanized at 170° C. to obtain a mixed rubber, the vulcanization curve of which is as follows: Figure 1 shown.

[0050] Example 6

[0051] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of 2-mercaptobenzothiazole tellurium (prepared in Example 3), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber by an open mill, and vulcanized at 170° C. to obtain a mixed rubber, the vulcanization curve of which is as follows: Figure 1 shown.

[0052] The vulcanization characteristics of SBR compound rubber materials were tested at 170°C using Taiwan U-Can UR-2030 dynamic die rheometer.

[0053] Figure 1 is the vulcanization curve of the vulcanized rubber obtained in Examples 4-6, Figure 1 It can be concluded that the vulcanization curves of the rubber mixes obtained in Examples 4, 5 and 6 are substantially identical, and the scorch time, vulcanization time and maximum torque are substantially the same, so the rubber mix of Example 4 is selected for comparison and illustration.

[0054] Example 7

[0055] 50 phr carbon black, 2.5 g sulfur masterbatch (sulfur content 80%), 1 g 2-mercaptobenzothiazole tellurium (prepared in Example 1), 5 g zinc oxide, and 1 g stearic acid were added to 100 g styrene-butadiene rubber by an open mill, and vulcanized at 170° C. to obtain a mixed rubber, which was recorded as SBR / N550 / TeM. Its thermal oxidation aging resistance is as follows: Figure 3 and Figure 4 shown.

[0056] Example 8

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

[0058] Example 9

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

[0060] Example 10

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

[0062] Comparative Example 1

[0063] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of 2-mercaptobenzothiazole (accelerator M), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber by an open mill, and vulcanized at 170°C to obtain a mixed rubber, which was recorded as SBR / M. Its vulcanization curve is shown in Figure 2 Its vulcanization parameters are shown in Table 1.

[0064] Comparative Example 2

[0065] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of dibenzothiazole disulfide (accelerator DM), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber through an open mill, and vulcanized at 170°C to obtain a mixed rubber, which was recorded as SBR / DM. Its vulcanization curve is as follows: Figure 2 Its vulcanization parameters are shown in Table 1.

[0066] Comparative Example 3

[0067] 2.5 g of sulfur masterbatch (sulfur content 80%), 1 g of selenobenzothiazole (accelerator SeM), 5 g of zinc oxide, and 1 g of stearic acid were added to 100 g of styrene-butadiene rubber by an open mill, and vulcanized at 170°C to obtain a mixed rubber, which was recorded as SBR / SeM. Its vulcanization curve is shown in Figure 2 Its vulcanization parameters are shown in Table 1.

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

[0069] Table 1 Vulcanization parameters of the rubber compounds obtained in Example 4 and Comparative Examples 1-3.

[0070]

[0071] The physical property parameters of the rubber mixtures obtained in Example 4 and Comparative Examples 1 to 3 are shown in Table 2. It can be seen from Table 2 that the physical properties of the 2-mercaptobenzothiazole tellurium vulcanized rubber are enhanced compared with the other two. Among them, the tensile strength is increased by 32.7% compared with SBR / M, 62% compared with SBR / DM, and 13% compared with SBR / SeM; the 100% elongation is increased by 14.3% compared with SBR / M, 11.4% compared with SBR / DM, and 8% compared with SBR / SeM; the 300% elongation is increased by 24.3% compared with SBR / M, 55% compared with SBR / DM, and 8% compared with SBR / SeM.

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

[0073]

[0074]

[0075] The heat-oxidative aging resistance of the rubber compounds obtained in Examples 7 to 10 is as follows: Figure 3 and Figure 4As shown in the figure, it can be seen that after the same aging time, the tensile strength retention rate and elongation at break of SBR / N550 / TeM are the highest, the tensile strength retention rate is about 10% higher than that of the other three accelerators, and the elongation at break retention rate is about 8% higher than that of the other three accelerators.

[0076] The infrared spectrum of 2-mercaptobenzothiazole tellurium prepared in Example 1 of the present invention is as follows: Figure 5 As shown, it can be seen from the figure that 3056 is the absorption peak of CH, 1490 is the absorption peak of C=C, 1594 is the absorption peak of C=N, 666 is the absorption peak of CS, and there are no SH and NH peaks in the spectrum, indicating that the synthesized substance is different from M.

[0077] The infrared spectra of other prepared 2-mercaptobenzothiazole tellurium are similar to that of Example 1.

[0078] Through elemental analysis, the present invention can obtain the element contents of C, H, S, and N, and further infer the possible chemical structure. Table 4 is the elemental analysis of 2-mercaptobenzothiazole tellurium prepared in Example 1. It can be observed that the actual value is consistent with the theoretical value, which fully demonstrates that 2-mercaptobenzothiazole tellurium is synthesized.

[0079] Table 4 Elemental analysis of 2-mercaptobenzothiazole tellurium

[0080]

[0081] The DSC thermal analysis curve of 2-mercaptobenzothiazole tellurium prepared in Example 1 of the present invention is as follows: Figure 6 Its TG thermal analysis curve is shown in Figure 7 As shown. Figure 6 and Figure 7 It can be seen that the melting point of the obtained product is 159°C, the decomposition temperature is 257°C, and there is only one thermal weight loss step, indicating that the obtained product is of high purity.

[0082] The above embodiments are only preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a rubber accelerator 2-mercaptobenzothiazole tellurium, characterized in that: The following steps are involved: 2-mercaptobenzothiazole and tellurium dioxide are dissolved in solvents respectively to obtain tellurium dioxide solution and 2-mercaptobenzothiazole solution; the tellurium dioxide solution is dropped into the 2-mercaptobenzothiazole solution, and the mixture is reacted under stirring to obtain rubber accelerator 2-mercaptobenzothiazole tellurium.

2. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The solvent is one or more of anhydrous ethanol, dichloromethane, acetone and dilute hydrochloric acid.

3. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The 2-mercaptobenzothiazole and tellurium dioxide are dissolved in a solvent respectively and stirred; the stirring rate of the stirring condition is 200 rpm-300 rpm.

4. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The concentration of the tellurium dioxide solution is 0.016 to 0.107 g / mL; The concentration of the 2-mercaptobenzothiazole solution is 0.045-0.053 g / mL.

5. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The molar ratio of the tellurium dioxide to 2-mercaptobenzothiazole is 1:3.5-5.

6. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The tellurium dioxide solution is dripped into the 2-mercaptobenzothiazole solution at a rate of one drop per second.

7. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: The reaction temperature is 4° C.-50° C., the reaction time is 2-3 hours; and the stirring rate in the stirring state is 200 rpm-300 rpm.

8. The method for preparing the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 1, characterized in that: After the reaction, the product is filtered, and the residue is washed, dried, crushed and sieved.

9. 2-Mercaptobenzothiazole tellurium, a rubber accelerator prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the rubber accelerator 2-mercaptobenzothiazole tellurium according to claim 9 in the preparation of vulcanized rubber.

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