Dithiocarbamic acid rubber vulcanization accelerator and its preparation method and application

Abstract

The application discloses a dithiocarbamic acid rubber vulcanization accelerator and a preparation method and application thereof; the dithiocarbamic acid rubber vulcanization accelerator provided by the application comprises at least one of zinc N'-methyl-N-piperazinyl dithiocarbamate, selenium N'-methyl-N-piperazinyl dithiocarbamate and tellurium N'-methyl-N-piperazinyl dithiocarbamate. The preparation method provided by the application uses a green solvent, and has the advantages of simple process, low energy consumption, short reaction time and high yield. The three efficient and environment-friendly dithiocarbamic acid rubber vulcanization accelerators, namely, zinc N'-methyl-N-piperazinyl dithiocarbamate, selenium and tellurium, have fast vulcanization rate and will not produce carcinogenic nitrosamine, and make up for the vacancy of the super-speed dithiocarbamic acid rubber vulcanization accelerator with high safety.

Description

Technical Field

[0001] This invention belongs to the technical field of rubber vulcanization accelerators, specifically relating to a dithiocarbamate rubber vulcanization accelerator, its preparation method, and its application. Background Technology

[0002] Rubber materials only have practical application value after vulcanization, which transforms the linear structure of rubber molecules from a slip-prone structure into a three-dimensional network structure. Rubber vulcanization accelerators are additives that assist rubber vulcanizing agents in improving the vulcanization behavior and structure of rubber, often accelerating the vulcanization rate.

[0003] Among rubber vulcanization accelerators, the type with the fastest vulcanization rate is the ultra-high-speed accelerator, whose molecular structure belongs to the dithiocarbamate class. This type of accelerator has an irreplaceable effect on accelerating the vulcanization reaction of low-activity rubber molecules such as ethylene propylene diene monomer (EPDM). Zinc diethyl dithiocarbamate (ZDC) is commonly used in industry.

[0004] With increasingly stringent environmental protection requirements, the greening of rubber products is an inevitable trend. The availability of ultra-high-speed accelerators has been greatly reduced due to the risk of producing nitrosamines, which are carcinogenic. Although zinc dibenzyl dithiocarbamate (ZBEC) ensures the safety of nitrosamines, it has lost the characteristics of ultra-high-speed accelerators. As an environmentally friendly accelerator, it is difficult to match the high efficiency of the traditional polluting accelerator ZDC. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of existing dithiocarbamate rubber vulcanization accelerators in achieving both high efficiency and environmental friendliness, and to enrich the variety of nitrosamine-safe ultra-high-speed rubber vulcanization accelerators, the present invention aims to provide three high-efficiency and environmentally friendly dithiocarbamate rubber vulcanization accelerators, namely zinc dithiocarbamate (ZMPDC), selenium (SMPDC), and tellurium (TMPDC), as well as their preparation methods and applications.

[0006] In the molecular structure of dithiocarbamate accelerators, the choice of amino substituents directly determines the ease of nitrosamine release. Generally speaking, the smaller the molecular weight and the less steric hindrance (e.g., short-chain alkyl groups), the higher the activity, the higher the risk of nitrosamine formation, and the faster the vulcanization rate. To balance the contradiction between environmental protection and high efficiency, we first adhere to amine structures instead of low-activity structures such as phosphoric acid that do not contain nitrogen atoms. Second, we explored the typical amino substituent structures of non-carcinogenic nitrosamine compounds. Finally, we selected the heterocyclic structure N'-methyl-N-piperazinyl with a suitable molecular weight. The central atom is chosen from zinc, selenium, and tellurium, which can serve as coordination centers and have flat vulcanization curves. Thus, these three novel dithiocarbamate rubber vulcanization accelerators maintain ultra-high-speed characteristics while also possessing the environmentally friendly properties of being safe from nitrosamines.

[0007] The ZMPDC, SMPDC, and TMPDC of this invention all use N'-methyl-N-piperazinyl, which is safe for nitrosamines, as side groups, and the central atom has a unique vulcanization behavior, giving rubber products excellent performance. They are a series of new rubber vulcanization accelerators that are both efficient and environmentally friendly. Their preparation process is based on the improvement of existing complex industrial production methods that produce a lot of waste liquid. It is simple, pollution-free, and easy to achieve mass production.

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

[0009] A dithiocarbamate rubber vulcanization accelerator, comprising at least one of N'-methyl-N-piperazinyl dithiocarbamate zinc, N'-methyl-N-piperazinyl dithiocarbamate selenium, and N'-methyl-N-piperazinyl dithiocarbamate tellurium.

[0010] The structural formula of zinc N'-methyl-N-piperazinyl dithiocarbamate is as follows:

[0011]

[0012] The structural formula of selenium N'-methyl-N-piperazinyl dithiocarbamate is as follows:

[0013]

[0014] The structural formula of N'-methyl-N-piperazinyl dithiocarbamate tellurium is as follows:

[0015]

[0016] The above-mentioned method for preparing dithiocarbamate rubber vulcanization accelerators.

[0017] (1) The preparation method of zinc N'-methyl-N-piperazinyl dithiocarbamate includes the following steps:

[0018] N-methylpiperazine was added to water, followed by zinc oxide. After the mixture was dispersed evenly, carbon disulfide was added dropwise. The mixture was heated to react. Once the white particles had completely precipitated, the mixture was washed, filtered, and dried to obtain zinc N'-methyl-N-piperazinyl dithiocarbamate.

[0019] (2) A method for preparing selenium N'-methyl-N-piperazinyl dithiocarbamate, comprising the following steps:

[0020] Selenium dioxide was added to ethanol, followed by N-methylpiperazine. After the mixture was evenly dispersed, carbon disulfide was added dropwise. The mixture was heated to react. Once the pale yellow particles had completely precipitated, the mixture was washed, filtered, and dried to obtain N'-methyl-N-piperazinyl dithiocarbamate selenium.

[0021] (3) The preparation method of N'-methyl-N-piperazinyl dithiocarbamate tellurium includes the following steps:

[0022] (A) Add sodium hydroxide aqueous solution to tellurium dioxide, heat and stir until the solution is clear to obtain a sodium hydroxide solution of tellurium dioxide;

[0023] (B) Mix sodium hydroxide aqueous solution and N-methylpiperazine, add carbon disulfide dropwise, then add tellurium dioxide sodium hydroxide solution, and heat to react;

[0024] (C) Add hydrochloric acid solution to the solution in step (B), heat to react, wash, filter and dry to obtain N'-methyl-N-piperazinyldithiocarbamate tellurium.

[0025] Preferably, in method (1), the concentration of N-methylpiperazine is 0.03–0.11 g / ml;

[0026] Preferably, in method (1), the molar ratio of N-methylpiperazine, zinc oxide, and carbon disulfide is (2-2.2):1:(2-2.2).

[0027] Preferably, in method (1), the reaction temperature is 30-50°C and the reaction time is 2-4 hours.

[0028] Preferably, in method (1), the preparation method of zinc N'-methyl-N-piperazinyl dithiocarbamate specifically includes the following steps:

[0029] N-methylpiperazine was added to deionized water under low temperature and stirring (stirring rate 1) conditions, followed by zinc oxide. After the mixture was evenly dispersed, carbon disulfide was slowly and uniformly added dropwise. After the addition was complete, the stirring speed was increased (stirring rate 2), and the mixture was slowly heated and kept at the temperature for reaction. After the white particles had completely precipitated, the mixture was cooled, washed, filtered, and dried to obtain zinc N'-methyl-N-piperazinyl dithiocarbamate.

[0030] Furthermore, the low temperature is 2–12°C.

[0031] Furthermore, the zinc oxide is sourced from commercially available 99% pure zinc oxide powder with a particle size of 100–1000 nm.

[0032] Furthermore, the dripping rate is 1–5 ml / min.

[0033] Furthermore, the stirring rate 1 is 400-600 rpm, and the stirring rate 2 is 800-1000 rpm.

[0034] Furthermore, the N-methylpiperazine is sourced from commercially available N-methylpiperazine with a purity of 99%.

[0035] Furthermore, the source of the carbon disulfide is commercially available carbon disulfide with a purity of 99%.

[0036] The zinc N'-methyl-N-piperazinyl dithiocarbamate provided by this invention is a white powder; the preparation method of zinc N'-methyl-N-piperazinyl dithiocarbamate provided by this invention has a yield of 77.0% to 84.1%.

[0037] Preferably, in method (2), the concentration of N-methylpiperazine is 0.06–0.22 g / ml;

[0038] Preferably, in method (2), the molar ratio of N-methylpiperazine, selenium dioxide, and carbon disulfide is (4-4.2):1:(4-4.2).

[0039] Preferably, in method (2), the reaction temperature is 30-50°C and the reaction time is 2-4 hours.

[0040] Preferably, in method (2), the preparation method of selenium N'-methyl-N-piperazinyl dithiocarbamate specifically includes the following steps:

[0041] Selenium dioxide was added to anhydrous ethanol under low temperature and stirring (stirring rate 1) conditions, followed by N-methylpiperazine. After the mixture was evenly dispersed, carbon disulfide was slowly and uniformly added dropwise. After the addition was complete, the stirring speed was increased (stirring rate 2), and the mixture was slowly heated and kept at the temperature for reaction. When the pale yellow particles were completely precipitated, the mixture was washed, filtered, and dried to obtain N'-methyl-N-piperazinyl dithiocarbamate selenium.

[0042] Furthermore, the low temperature is 2–12°C.

[0043] Furthermore, the dripping rate is 1–5 ml / min.

[0044] Furthermore, the stirring rate 1 is 400-600 rpm, and the stirring rate 2 is 800-1000 rpm.

[0045] Furthermore, the selenium dioxide is sourced from commercially available selenium dioxide with a purity of 99%.

[0046] Furthermore, the N-methylpiperazine is sourced from commercially available N-methylpiperazine with a purity of 99%.

[0047] Furthermore, the source of the carbon disulfide is commercially available carbon disulfide with a purity of 99%.

[0048] The N'-methyl-N-piperazinyl dithiocarbamate selenium provided by this invention is a pale yellow powder; the preparation method of N'-methyl-N-piperazinyl dithiocarbamate selenium provided by this invention has a yield of 77.0% to 85.0%.

[0049] Preferably, in method (3), the mass fraction of the sodium hydroxide aqueous solution is 2% to 3%;

[0050] Preferably, in method (3), the reaction temperature in step (B) is 50–70°C, and the reaction time is 1–3 h;

[0051] Preferably, in method (3), the molar ratio of sodium hydroxide, tellurium dioxide in step (A), sodium hydroxide, N-methylpiperazine, and carbon disulfide in step (B) is (2-2.2):1:(4-4.2):(4-4.2):(4-4.2).

[0052] Preferably, in method (3), the mass fraction of the hydrochloric acid solution is 35% to 38%;

[0053] Preferably, in method (3), the molar ratio of hydrochloric acid to sodium hydroxide is 1 to 1.2:1;

[0054] Preferably, in method (3), the reaction temperature in step (C) is 50-70°C and the reaction time is 1-3 hours.

[0055] Preferably, in method (3), the preparation method of N'-methyl-N-piperazinyl dithiocarbamate tellurium specifically includes the following steps:

[0056] Prepare a sodium hydroxide aqueous solution with a certain mass fraction, add an appropriate amount to tellurium dioxide, and heat and stir until the solution is clear; add the remaining sodium hydroxide aqueous solution and N-methylpiperazine to a flask, and stir at low temperature (stirring rate 1); slowly and uniformly add carbon disulfide, and after the addition is complete, slowly heat, then add hot sodium hydroxide solution of tellurium dioxide and react fully for a period of time, then add a certain amount of hydrochloric acid, then increase the stirring speed (stirring rate 2), and continue to react for a period of time; finally, wash, filter, and dry to obtain N'-methyl-N-piperazinyldithiocarbamate tellurium.

[0057] Furthermore, the sodium hydroxide aqueous solution is added to tellurium dioxide, and the temperature reached by heating after the addition is complete is 50-70°C.

[0058] Furthermore, the low temperature is 2–12°C.

[0059] Furthermore, the dripping rate is 1–5 ml / min.

[0060] Furthermore, the stirring rate 1 is 400-600 rpm, and the stirring rate 2 is 800-1000 rpm.

[0061] Furthermore, the tellurium dioxide is sourced from commercially available tellurium dioxide with a purity of 99%.

[0062] Furthermore, the N-methylpiperazine is sourced from commercially available N-methylpiperazine with a purity of 99%.

[0063] Furthermore, the source of the carbon disulfide is commercially available carbon disulfide with a purity of 99%.

[0064] Furthermore, the sodium hydroxide is sourced from commercially available sodium hydroxide with a purity of 99%.

[0065] The N'-methyl-N-piperazinyl dithiocarbamate tellurium provided by this invention is an orange-red powder; the preparation method of N'-methyl-N-piperazinyl dithiocarbamate tellurium provided by this invention has a yield of 64.0% to 69.0%.

[0066] The above-mentioned dithiocarbamate rubber vulcanization accelerators are used in the preparation of vulcanized rubber.

[0067] Styrene-butadiene rubber, as a chain olefin, contains weakly electron-withdrawing phenyl and vinyl side groups, but lacks electron-donating methyl groups that enhance the reactivity of double bonds. This facilitates the amplification of the role of accelerators in the sulfur vulcanization system and reduces interference from its own molecular structure.

[0068] Preferably, the vulcanized rubber comprises the following components in parts by weight: 100-120 parts styrene-butadiene rubber, 5-8 parts zinc oxide, 1-2 parts stearic acid, 2-3 parts sulfur, and 1-3 parts dithiocarbamate rubber vulcanization accelerator.

[0069] Further, the vulcanized rubber comprises the following components in parts by weight: 100 parts styrene-butadiene rubber, 5 parts zinc oxide, 1 part stearic acid, 2 parts sulfur, and 1 part zinc N'-methyl-N-piperazinyl dithiocarbamate.

[0070] Or 100 parts styrene-butadiene rubber, 5 parts zinc oxide, 1 part stearic acid, 2 parts sulfur, and 1 part N'-methyl-N-piperazinyl dithiocarbamate selenium;

[0071] Alternatively, 100 parts styrene-butadiene rubber, 5 parts zinc oxide, 1 part stearic acid, 2 parts sulfur, and 1 part N'-methyl-N-piperazinyldithiocarbamate tellurium.

[0072] The above three new high-efficiency and environmentally friendly accelerators produce styrene-butadiene rubber with better vulcanization performance than styrene-butadiene rubber prepared with commonly used vulcanization accelerators ZDC and ZBEC. Moreover, the production process does not generate waste gas and does not use hazardous chemical raw materials such as toxic gases, highly toxic substances or carcinogens.

[0073] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0074] (1) The preparation method provided by the present invention uses green solvents, has a simple process, low energy consumption, short reaction time, and high yield.

[0075] (2) The three high-efficiency and environmentally friendly dithiocarbamate rubber vulcanization accelerators N'-methyl-N-piperazinyl dithiocarbamate zinc, selenium and tellurium provided by the present invention not only have a fast vulcanization rate, but also do not produce carcinogenic nitrosamines, filling the gap in the variety of ultra-fast dithiocarbamate rubber vulcanization accelerators that are safe for nitrosamines. Attached Figure Description

[0076] Figure 1 The vulcanization curves are for the rubber compounds prepared in Examples 4, 5, and 6 and Comparative Examples 1 and 2.

[0077] Figure 2 Infrared spectra of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators, namely zinc, selenium, and tellurium N'-methyl-N-piperazinyl dithiocarbamate, prepared in Examples 1, 2, and 3.

[0078] Figure 3 Raman spectra of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators, namely zinc, selenium, and tellurium N'-methyl-N-piperazinyl dithiocarbamate, prepared in Examples 1, 2, and 3.

[0079] Figure 4 DSC curves of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators, namely zinc, selenium, and tellurium N'-methyl-N-piperazinyl dithiocarbamate, prepared in Examples 1, 2, and 3.

[0080] Figure 5 The TG curves are for three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators, namely zinc, selenium, and tellurium N'-methyl-N-piperazinyl dithiocarbamate, prepared in Examples 1, 2, and 3.

[0081] Figure 6 The images show the appearance of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators prepared in Examples 1, 2, and 3: zinc, selenium, and tellurium dithiocarbamates; and the styrene-butadiene rubber compounds and vulcanizates prepared in Examples 4, 5, and 6. Detailed Implementation

[0082] 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.

[0083] Example 1

[0084] (1) Add 300ml of deionized water to the flask, place the flask in ice water, and keep the temperature reading at about 10℃.

[0085] (2) Add 10.17 g (0.1 mol) of N-methylpiperazine to the flask and set the magnetic stir bar speed to 560 rpm;

[0086] (3) Add 4.07g (0.05mol) of zinc oxide (particle size 200nm) to the flask to make the zinc oxide particles evenly dispersed;

[0087] (4) Using a constant pressure dropping funnel to control the dropping rate (dropping rate of 3 ml / min), slowly add 7.62 g (0.1 mol) of carbon disulfide to the flask, and keep the reaction system at 10 °C;

[0088] (5) Increase the rotation speed to 820 rpm, slowly heat to 30°C, react for 3 hours, and after the white particles have completely precipitated, let it cool down to room temperature naturally.

[0089] (6) Wash, filter using a vacuum pump, and then place the product in a vacuum drying oven and dry at 60°C for 2 hours to obtain zinc N'-methyl-N-piperazinyl dithiocarbamate with a yield of 77%.

[0090] Example 2

[0091] (1) Add 300 ml of anhydrous ethanol to the flask, place the flask in ice water, keep the temperature reading at about 10°C, then add 5.60 g (0.05 mol) of selenium dioxide, and set the rotation speed to 600 rpm;

[0092] (2) Add 20.33 g (0.2 mol) of N-methylpiperazine to the flask and disperse it evenly;

[0093] (3) Slowly add 15.23 g (0.2 mol) of carbon disulfide (dropping rate of 3 ml / min), and increase the rotation speed to 800 rpm to ensure uniform dispersion of particles;

[0094] (4) Slowly heat to 30°C and react for 3 hours. After the pale yellow particles have completely precipitated, let them cool down to room temperature naturally.

[0095] (5) Wash, filter using a vacuum pump, and then place the product in a vacuum drying oven and dry at 60°C for 3 hours to obtain selenium N'-methyl-N-piperazinyl dithiocarbamate with a yield of 77%.

[0096] Example 3

[0097] (1) Dissolve 6.25g (0.15mol) sodium hydroxide in 250g deionized water to prepare a sodium hydroxide aqueous solution with a mass fraction of 2.4%;

[0098] (2) Take one-third of the prepared sodium hydroxide aqueous solution, i.e., 85.42g, and add it to 3.99g (0.025mol) of tellurium dioxide. Heat to 50℃ and stir until the solution is clear.

[0099] (3) Add the remaining sodium hydroxide aqueous solution and 10.17 g (0.1 mol) N-methylpiperazine to the flask, keep the system temperature at about 10 °C, start stirring, and stir at 560 rpm for 2 h.

[0100] (4) Use a constant pressure dropping funnel to control the dropping rate (dropping rate is 3 ml / min), slowly add 7.62 g (0.1 mol) carbon disulfide to the flask in step (3), and after the addition is complete, raise the temperature to 50°C, add the hot tellurium dioxide solution previously dissolved in sodium hydroxide to the flask, and react for 3 h. At this time, no precipitate appears.

[0101] (5) Take 14.39g of 38% hydrochloric acid (0.15mol) solution and add it to the flask. The reaction system changes from alkaline to neutral. The product dissolved in the alkali instantly produces an orange-red precipitate.

[0102] (6) Increase the rotation speed to 810 rpm and continue the reaction at 50°C for 2 hours;

[0103] (7) Wash, filter using a vacuum pump, place the product in a vacuum drying oven, dry at 60°C for 2 hours, rinse with deionized water two to three times to remove sodium chloride, and finally dry to obtain N'-methyl-N-piperazinyl dithiocarbamate tellurium, with a yield of 64%.

[0104] Example 4

[0105] 5g of zinc oxide, 1g of stearic acid, 2g of sulfur, and 1g of zinc N'-methyl-N-piperazinyl dithiocarbamate (prepared in Example 1) were sequentially added to 100g of styrene-butadiene rubber using a two-roll mill to obtain a compound, denoted as SBR / ZMPDC. The vulcanized rubber was obtained by testing with a rotorless vulcanizer at 150°C, and its vulcanization curve is shown below. Figure 1 As shown in Table 1, the vulcanization parameters are as follows.

[0106] Example 5

[0107] 5g of zinc oxide, 1g of stearic acid, 2g of sulfur, and 1g of N'-methyl-N-piperazinyl dithiocarbamate selenium (prepared in Example 2) were sequentially added to 100g of styrene-butadiene rubber using an open mill to obtain a compound, denoted as SBR / SMPDC. The vulcanized rubber was obtained by testing with a rotorless vulcanizer at 150°C, and its vulcanization curve is shown below. Figure 1 As shown in Table 1, the vulcanization parameters are as follows.

[0108] Example 6

[0109] 5g of zinc oxide, 1g of stearic acid, 2g of sulfur, and 1g of N'-methyl-N-piperazinyl dithiocarbamate tellurium (prepared in Example 3) were sequentially added to 100g of styrene-butadiene rubber using an open mill to obtain a compound, denoted as SBR / TMPDC. The vulcanized rubber was obtained by testing with a rotorless vulcanizer at 150°C, and its vulcanization curve is shown below. Figure 1 As shown in Table 1, the vulcanization parameters are as follows.

[0110] Comparative Example 1

[0111] 5g zinc oxide, 1g stearic acid, 2g sulfur, and 1g accelerator ZDC (purchased from Dongguan Siqi Rubber Technology Co., Ltd.) were sequentially added to 100g styrene-butadiene rubber using an open mill to obtain a compound, denoted as SBR / ZDC. The vulcanized rubber was then tested at 150℃ using a rotorless vulcanizer, and its vulcanization curve is shown below. Figure 1 As shown in Table 1, the vulcanization parameters are as follows.

[0112] Comparative Example 2

[0113] 5g zinc oxide, 1g stearic acid, 2g sulfur, and 1g accelerator ZBEC (purchased from Dongguan Siqi Rubber Technology Co., Ltd.) were sequentially added to 100g styrene-butadiene rubber using an open mill to obtain a compound, denoted as SBR / ZBEC. The vulcanized rubber was then tested at 150℃ using a rotorless vulcanizer, and its vulcanization curve is shown below. Figure 1 As shown in Table 1, the vulcanization parameters are as follows.

[0114] The vulcanization parameters of the rubber compounds obtained in Examples 4, 5, and 6 and Comparative Examples 1 and 2 are shown in Table 1, and the vulcanization curves are shown in Table 2. Figure 1 From Table 1 and Figure 1 It can be seen that the styrene-butadiene rubber (SBR) produced by ZMPDC, SMPDC, and TMPDC, which are safe against nitrosamines, has a shorter scorch time, around two minutes and thirty seconds, which is faster than that produced by ZDC, a traditional accelerator that is unsafe due to scorch and nitrosamines. SMPDC and TMPDC generally have a higher degree of crosslinking, while ZBEC has the lowest degree of crosslinking. ZMPDC SBR has the fastest vulcanization rate, faster than that produced by the traditional ultra-fast accelerator ZDC.

[0115] Table 1. Vulcanization parameters of the rubber compounds obtained in Examples 4, 5, and 6 and Comparative Examples 1 and 2.

[0116]

[0117] The infrared spectra of the three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators N'-methyl-N-piperazinyl dithiocarbamate zinc, selenium, and tellurium prepared in Examples 1, 2, and 3 of this invention are shown below. Figure 2As shown in the figure, it can be seen that: 2750~3000cm -1 Area (2792cm) -1 2784cm -1 2933cm -1 2938cm -1 The stretching vibration peaks of the CH bonds in -CH3- and -CH2- were observed, at 1200–1300 cm⁻¹. -1 Area (1233cm) -1 1236cm -1 The appearance of -CH3- and -CH2- CH bond bending vibration peaks corresponds to the methylpiperazine ring structure; in the range of 1470–1497 cm⁻¹ -1 Area (1485cm) -1 1474cm -1 1480cm -1 The characteristic absorption peak of the CN bond appears, especially at the CN single bond (1250-1350 cm⁻¹). -1 ) and C=N double bonds (1640-1690 cm⁻¹) -1 The peak between 1291cm indicates that the CN bond represented by this peak has partial double bond properties, corresponding to the CN bond connected to -CSS-; -1 1282cm -1 1287cm -1 Corresponding to the CN single bond connecting the methyl group and the piperazine ring; 1150 cm -1 Nearby (1141cm) -1 1158cm -1 () is an antisymmetric stretching vibration of -CSS-, 990cm -1 Nearby (990cm) -1 994cm -1 986cm -1 ) is a symmetrical stretching vibration of -CSS-.

[0118] The Raman spectra of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators prepared in Examples 1, 2, and 3 of this invention, namely zinc, selenium, and tellurium N'-methyl-N-piperazinyl dithiocarbamate, are shown below. Figure 3 As shown in the figure, it can be seen that on the ZMPDC spectral line, at 134 cm⁻¹... -1 This corresponds to a lattice vibration at 164 cm⁻¹. -1 The location may be due to Zn-S vibrational coupling with ligands, 410 cm. -1 441cm -1 This corresponds to the out-of-plane deformation of CNC in two different chemical environments, with the Zn-S stretching vibration appearing at 492 cm⁻¹. -1 At 547 cm⁻¹, the stretching vibration of CN occurs.-1 At; on the SMPDC spectral line, 128 cm⁻¹ -1 This corresponds to lattice vibrations; the Se-S bending vibration occurs at 158 ​​cm⁻¹. -1 At this point, the bending vibration of S-Se-S appears at 220cm. -1 At 364 cm⁻¹, the stretching vibration of Se-S occurs. -1 Location, 421cm -1 443cm -1 This corresponds to the out-of-plane deformation of CNC in two different chemical environments; on the TMPDC spectral line, 133 cm⁻¹ -1 This corresponds to lattice vibrations; the Te-S bending vibration appears at 152 cm⁻¹. -1 At this point, the bending vibration of S-Te-S occurs at 220 cm. -1 At 314 cm⁻¹, the stretching vibration of Te-S appears. -1 and 354cm -1 Location, 414cm -1 This corresponds to the out-of-plane deformation of the CNC machine; the stretching vibration of the CN occurs at 546cm. -1 and 570cm -1 Place.

[0119] The main characteristic groups of ZMPDC, SMPDC, and TMPDC were characterized by a combination of infrared spectroscopy and Raman analysis.

[0120] The DSC curves of three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators, N'-methyl-N-piperazinyl dithiocarbamate zinc, selenium, and tellurium, prepared in Examples 1, 2, and 3 of this invention are shown below. Figure 4 As shown, the TG curve is as follows Figure 5 As shown. From Figure 4 and Figure 5It can be seen that: ZMPDC has a melting point of 262.0℃ and a decomposition temperature of 314.4℃; SMPDC has a melting point of 141.8℃ and a decomposition temperature of 180.6℃; and TMPDC has a melting point of 146.4℃ and a decomposition temperature of 207.1℃. None of the three showed weight loss around 100℃, indicating the absence of water of crystallization in their structures. The three single peaks in the DSC curves indicate high sample purity. ZMPDC's melting point is significantly higher than that of SMPDC and TMPDC, and its peak is narrow and sharp, indicating complete crystallization. SMPDC's melting point is slightly lower than that of TMPDC, and its peaks are wider, suggesting potentially less complete crystallization. ZMPDC can cover various vulcanization temperature ranges of rubber and will not fail due to decomposition, but its fluidity during vulcanization is poor, requiring uniform dispersion during mixing. SMPDC and TMPDC should be avoided at temperatures above 180℃ to prevent decomposition and failure; however, they melt during vulcanization, making them more fluid and contributing to improved rubber crosslinking.

[0121] The appearance of the three highly efficient and environmentally friendly dithiocarbamate rubber vulcanization accelerators N'-methyl-N-piperazinyl dithiocarbamate zinc, selenium, and tellurium prepared in Examples 1, 2, and 3 of this invention, as well as the styrene-butadiene rubber compound and vulcanizate prepared in Examples 4, 5, and 6, are as follows: Figure 6 As shown. From Figure 6 It can be seen that: ZMPDC is a white powder, and the styrene-butadiene rubber compound prepared from it is also white, turning light yellow after vulcanization, making it a good choice for light-colored rubber products; SMPDC is a pale yellow powder, and the styrene-butadiene rubber compound prepared from it is also pale yellow, turning orange-yellow after vulcanization, with the color deepening, requiring proper matching of color masterbatch for colored rubber products; TMPDC is an orange powder, and the styrene-butadiene rubber compound prepared from it is also orange, but turning black after vulcanization, making it more suitable for use in carbon black-filled rubbers. These color changes also reflect the differences in the products after the vulcanization reaction, especially since the black SBR / TMPDC may be amorphous tellurium powder, similar in appearance to carbon black reinforcing rubber.

[0122] The above embodiments are 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, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A vulcanized rubber composition, characterized in that, The product comprises the following components in parts by weight: 100-120 parts styrene-butadiene rubber, 5-8 parts zinc oxide, 1-2 parts stearic acid, 2-3 parts sulfur, and 1-3 parts dithiocarbamate rubber vulcanization accelerator; wherein the dithiocarbamate rubber vulcanization accelerator is at least one selected from N'-methyl-N-piperazinyl dithiocarbamate zinc, N'-methyl-N-piperazinyl dithiocarbamate selenium, and N'-methyl-N-piperazinyl dithiocarbamate tellurium. The structural formula of selenium N'-methyl-N-piperazinyl dithiocarbamate is as follows: The structural formula of N'-methyl-N-piperazinyl dithiocarbamate tellurium is as follows: 。 2. The vulcanized rubber composition according to claim 1, characterized in that, The N'-methyl-N-piperazinyl dithiocarbamate selenium is obtained by a preparation method including the following steps: selenium dioxide is added to ethanol, then N-methylpiperazine is added, dispersed evenly, carbon disulfide is added dropwise, the reaction is heated, and after the pale yellow particles are completely precipitated, the mixture is washed, filtered, and dried to obtain the product; wherein, the molar ratio of N-methylpiperazine, selenium dioxide, and carbon disulfide is (4-4.2):1:(4-4.2), the reaction temperature is 30-50℃, and the reaction time is 2-4h.

3. The vulcanized rubber composition according to claim 1, characterized in that, The N'-methyl-N-piperazinyl dithiocarbamate tellurium is obtained by a preparation method comprising the following steps: (A) Add an aqueous solution of sodium hydroxide to tellurium dioxide, heat and stir until the solution is clear to obtain a sodium hydroxide solution of tellurium dioxide; (B) Mix sodium hydroxide aqueous solution and N-methylpiperazine, add carbon disulfide dropwise, then add tellurium dioxide sodium hydroxide solution, and heat to react; (C) Add hydrochloric acid solution to the solution obtained in step (B), heat to react, wash, filter and dry to obtain the product; In step (A), the molar ratio of sodium hydroxide, tellurium dioxide, sodium hydroxide, N-methylpiperazine, and carbon disulfide is (2-2.2):1:(4-4.2):(4-4.2):(4-4.2). The reaction temperature in steps (B) and (C) is 50-70℃, and the reaction time is 1-3h.

4. The use of the vulcanized rubber composition according to any one of claims 1-3 in the preparation of vulcanized rubber articles.

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