The invention relates to N, Napos; zinc-methylcyclohexyl dithiocarbamate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of rubber vulcanization, and particularly relates to zinc N, N '-methylcyclohexyl dithiocarbamate as well as a preparation method and application thereof. The invention provides zinc N, N '-methylcyclohexyl dithiocarbamate, and the structural formula of the zinc N, N'-methylcyclohexyl dithiocarbamate is shown as a formula I. The zinc N, N '-methylcyclohexyl dithiocarbamate disclosed by the invention is used as a vulcanization accelerator, is not easy to nitrose in a rubber product processing process, is safe and environment-friendly, and can be used for replacing vulcanization accelerators such as zinc diethyl dithiocarbamate, zinc di-n-butyl dithiocarbamate and zinc dibenzyl dithiocarbamate. The zinc N, N '-methylcyclohexyl dithiocarbamate provided by the invention is a novel and friendly rubber additive, and has a good application prospect in the rubber industry. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of rubber vulcanization, and specifically relates to zinc N,N'-methylcyclohexyldithiocarbamate and a preparation method and application thereof. Background Art

[0002] Rubber vulcanization accelerator is an important auxiliary agent in rubber vulcanization, which has many advantages such as promoting rubber vulcanization, shortening vulcanization time, lowering vulcanization temperature, reducing the amount of vulcanizer and improving the physical and mechanical properties of vulcanized rubber. Currently, zinc diethyldithiocarbamate (accelerator ZDEC) and zinc di-n-butyldithiocarbamate (accelerator ZDBC) are widely used. However, the above-mentioned vulcanization accelerators will produce excessive nitrosamines with carcinogenic risks during the processing of rubber products, such as diethylnitrosamine (NDEA) and dibutylnitrosamine (NDBA). Therefore, it is urgent to develop a safe and environmentally friendly rubber vulcanization accelerator. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a zinc N,N'-methylcyclohexyl dithiocarbamate and a preparation method and application thereof. The zinc N,N'-methylcyclohexyl dithiocarbamate of the present invention is not easy to nitrosate, is safe and environmentally friendly, and can replace the vulcanization accelerator zinc diethyl dithiocarbamate and zinc di-n-butyl dithiocarbamate.

[0004] The present invention provides a zinc N,N′-methylcyclohexyldithiocarbamate, the structural formula of which is shown in Formula I:

[0005]

[0006] The present invention also provides a method for preparing the N,N′-methylcyclohexyl zinc dithiocarbamate described in the above technical solution, comprising the following steps:

[0007] mixing carbon disulfide, zinc oxide, a surfactant and water to obtain a suspension;

[0008] N-methylcyclohexylamine is added dropwise to the suspension to react, thereby obtaining zinc N,N′-methylcyclohexyldithiocarbamate.

[0009] Preferably, the molar ratio of carbon disulfide to zinc oxide is 1-1.5:0.5-0.6.

[0010] Preferably, the surfactant includes one or more of dodecylphenol polyoxyethylene ether, Tween-20 and fatty alcohol polyoxyethylene ether.

[0011] Preferably, the mass of the surfactant is 0.5% to 2% of the mass of zinc oxide.

[0012] Preferably, the carbon disulfide, zinc oxide, surfactant and water are mixed under stirring conditions, the mixing temperature is 25 to 45° C., and the mixing time is 1 to 3 hours.

[0013] Preferably, the molar ratio of N-methylcyclohexylamine to carbon disulfide is 1:1 to 1.5.

[0014] Preferably, the reaction temperature is 80-90° C. and the reaction time is 3-6 hours.

[0015] The present invention also provides the use of the N,N′-methylcyclohexyl zinc dithiocarbamate described in the above technical solution or the N,N′-methylcyclohexyl zinc dithiocarbamate obtained by the above preparation method as a vulcanization accelerator.

[0016] Preferably, the application is application in rubber vulcanization, the rubber includes natural rubber or synthetic rubber, and the mass ratio of the zinc N,N′-methylcyclohexyldithiocarbamate to the rubber is 0.2-0.6:100.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a zinc N,N′-methylcyclohexyldithiocarbamate, the structural formula of which is shown in Formula I:

[0019]

[0020] The N,N′-methylcyclohexyl zinc dithiocarbamate of the present invention is used as a vulcanization accelerator. It is not easy to nitrosate during the processing of rubber products, and it is not easy to produce carcinogenic nitrosamines. It is safe and environmentally friendly, and can replace the currently used vulcanization accelerators such as zinc diethyl dithiocarbamate and zinc di-n-butyl dithiocarbamate, thereby overcoming the disadvantage that the current vulcanization accelerators can produce excessive nitrosamines during the processing of rubber products.

[0021] The present invention also provides a method for preparing the N,N′-methylcyclohexyl zinc dithiocarbamate described in the above technical solution. The present invention uses N-methylcyclohexylamine to react with zinc oxide and carbon disulfide to synthesize a cyclohexyl-containing aminothiocarbamate zinc salt compound for the first time. The preparation method of the present invention is simple, has a short process, high operational safety, and good application performance, and is conducive to industrial production and promotion and use in the rubber industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is the hydrogen spectrum of N,N′-methylcyclohexyl zinc dithiocarbamate prepared in Example 1;

[0024] Figure 2 This is the carbon spectrum of N,N′-methylcyclohexyl zinc dithiocarbamate prepared in Example 2;

[0025] Figure 3 This is the vulcanization curve of zinc N,N′-methylcyclohexyl dithiocarbamate and vulcanization accelerators ZDBC and ZDEC at 140°C in the basic formula of natural rubber in Application Example 1;

[0026] Figure 4 This is the vulcanization curve of N,N′-methylcyclohexyl dithiocarbamate zinc and vulcanization accelerators ZDBC and ZDEC at 120°C in the basic formula of natural rubber in Application Example 2. DETAILED DESCRIPTION

[0027] The present invention provides a zinc N,N′-methylcyclohexyldithiocarbamate, the structural formula of which is shown in Formula I:

[0028]

[0029] The N,N′-methylcyclohexyl zinc dithiocarbamate of the present invention is used as a vulcanization accelerator to overcome the disadvantage that zinc diethyl dithiocarbamate (accelerator ZDEC) and zinc di-n-butyl dithiocarbamate (accelerator ZDBC) will produce excessive nitrosamines during the processing of rubber products.

[0030] The N,N′-methylcyclohexyl zinc dithiocarbamate of the present invention is an environmentally friendly zinc dithiocarbamate that is not prone to nitrosation.

[0031] The present invention also provides a method for preparing the N,N′-methylcyclohexyl zinc dithiocarbamate described in the above technical solution, comprising the following steps:

[0032] mixing carbon disulfide, zinc oxide, a surfactant and water to obtain a suspension;

[0033] N-methylcyclohexylamine is added dropwise to the suspension to react, thereby obtaining zinc N,N′-methylcyclohexyldithiocarbamate.

[0034] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0035] The invention mixes carbon disulfide, zinc oxide, a surfactant and water to obtain a suspension.

[0036] In the present invention, the molar ratio of carbon disulfide to zinc oxide is preferably 1-1.5:0.5-0.6, specifically 1.3:0.52 or 1.38:0.54.

[0037] In the present invention, the surfactant preferably includes one or more of dodecylphenol polyoxyethylene ether (OP-10), Tween-20 (Tween-20) and fatty alcohol polyoxyethylene ether.

[0038] In the present invention, the mass of the surfactant is preferably 0.5% to 2% of the mass of zinc oxide, and specifically may be 1.2% or 1.4%.

[0039] In the present invention, the mass ratio of zinc oxide to water is preferably 10-30:250, and specifically may be 22:250.

[0040] In the present invention, the carbon disulfide, zinc oxide, surfactant and water are preferably mixed under stirring conditions, the mixing temperature is preferably 25 to 45° C., specifically 25 to 30° C., the time is preferably 1 to 3 hours, specifically 2 hours. The zinc oxide is evenly dispersed during the stirring process.

[0041] After obtaining the suspension, the present invention drips N-methylcyclohexylamine into the suspension for reaction to obtain N,N′-methylcyclohexyl zinc dithiocarbamate.

[0042] In the present invention, the molar ratio of N-methylcyclohexylamine to carbon disulfide is preferably 1:1 to 1.5, specifically 1:1.3.

[0043] In the present invention, the temperature of the suspension during the dropwise addition is preferably 25 to 45° C., specifically 25 to 30° C. The present invention has no special requirements for the dropwise addition rate, and the dropwise addition rate commonly used by those skilled in the art can be used.

[0044] In the present invention, the reaction temperature is preferably 80-90°C, and the reaction time is preferably 3-6 hours. The reaction includes a condensation reaction and a double decomposition salt formation reaction, and the reaction formula is as follows:

[0045]

[0046] In the present invention, after the reaction, the process preferably further comprises: cooling the reaction liquid obtained by the reaction to room temperature, solid-liquid separation, drying and crushing; the solid-liquid separation method is preferably filtration; the drying temperature is preferably 90°C, and the time is preferably dried to constant weight; the present invention has no special requirements for the crushing method, and the particle size (D90) after crushing is preferably 10 to 25 μm.

[0047] The present invention also provides the use of the N,N′-methylcyclohexyl zinc dithiocarbamate described in the above technical solution or the N,N′-methylcyclohexyl zinc dithiocarbamate obtained by the above preparation method as a vulcanization accelerator.

[0048] In the present invention, the application is preferably application in rubber vulcanization, and the rubber preferably includes natural rubber or synthetic rubber.

[0049] In the present invention, the mass ratio of the zinc N,N′-methylcyclohexyldithiocarbamate to the rubber is preferably 0.2-0.6:100, and the specific usage ratio may be 0.442:100 (1 mmol:100 g).

[0050] The N,N′-methylcyclohexyl zinc dithiocarbamate of the present invention is used as a rubber vulcanization accelerator, has similar vulcanization properties to zinc diethyl dithiocarbamate (ZDEC) and zinc di-n-butyl dithiocarbamate (ZDBC), and can replace zinc diethyl dithiocarbamate or zinc di-n-butyl dithiocarbamate.

[0051] In order to further illustrate the present invention, the N,N′-methylcyclohexyl zinc dithiocarbamate and its preparation method and application provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0052] In the embodiments and application examples of the present invention, OP-10 is dodecylphenol polyoxyethylene ether, ZDBC is the accelerator zinc di-n-butyl dithiocarbamate, and ZDEC is the accelerator zinc diethyl dithiocarbamate.

[0053] Example 1

[0054] At room temperature, 250.0g water, 0.3g OP-10, 22.2g zinc oxide (0.27mol), and 52.3g carbon disulfide (0.69mol) were sequentially placed in a four-necked flask with a condenser, and the temperature was slowly raised to 25°C and stirred for 2h. At 25°C, 60.0g N-methylcyclohexylamine (0.53mol) was added dropwise, and the temperature was raised to 80°C for reaction for 3h after completion. The mixture was cooled to room temperature, filtered, dried (90°C, dried to constant weight), and crushed (particle size analyzer test: D90 = 10-25μm) to obtain 115.2g of N,N′-methylcyclohexyl zinc dithiocarbamate, with a yield of 99.3%, an initial melting point of 198°C, and a Zn mass content of 14.9%.

[0055] Figure 1 This is the hydrogen spectrum of N,N′-methylcyclohexyl zinc dithiocarbamate prepared in Example 1.

[0056] Example 2

[0057] At room temperature, 250.0g of water, 0.3g of Tween-20, 22.2g of zinc oxide, and 52.3g of carbon disulfide were sequentially placed in a four-necked flask with a condenser, and the temperature was slowly raised to 25°C and stirred for 2h. At 25°C, 60.0g of N-methylcyclohexylamine was added dropwise, and the temperature was raised to 80°C for reaction for 3h after completion. The mixture was cooled to room temperature, filtered, dried (90°C, dried to constant weight), and crushed (particle size analyzer test: D90 = 10-25μm) to obtain 115.6g of N,N′-methylcyclohexyl zinc dithiocarbamate, with a yield of 99.7%, an initial melting point of 199°C, and a Zn mass content of 14.8%.

[0058] Figure 2 This is the carbon spectrum of N,N′-methylcyclohexyl zinc dithiocarbamate prepared in Example 2.

[0059] Application Example 1

[0060] The zinc N,N′-methylcyclohexyl dithiocarbamate, ZDBC and ZDEC prepared in Example 1 were used as vulcanization accelerators, and rubber was prepared by mixing in a rubber mixer (vulcanization temperature 140° C.). The basic formula is shown in Table 1:

[0061] Table 1 Basic formula of rubber in application example 1

[0062]

[0063] The vulcanization curves of zinc N,N′-methylcyclohexyl dithiocarbamate compounds, ZDBC compounds and ZDEC compounds are shown in Figure 3 , where 1 is ZDBC, 2 is N,N′-methylcyclohexyl zinc dithiocarbamate, and 3 is ZDEC; the vulcanization characteristic parameters are shown in Table 2:

[0064] Table 2 Vulcanization characteristic parameters of application example 1

[0065]

[0066]

[0067] from Figure 3 It can be seen from Table 2 that when the same dosage of N,N′-methylcyclohexyl zinc dithiocarbamate and vulcanization accelerators ZDBC and ZDEC are used, under the vulcanization condition of 140°C, the minimum torque, maximum torque, scorch time, positive vulcanization time and vulcanization rate index are basically similar. N,N′-methylcyclohexyl zinc dithiocarbamate has similar vulcanization characteristics (vulcanization process) as the vulcanization accelerator ZDBC.

[0068] Application Example 2

[0069] The zinc N,N′-methylcyclohexyl dithiocarbamate, ZDBC and ZDEC prepared in Example 2 were used as vulcanization accelerators, and rubber was prepared by mixing in a rubber mixer (vulcanization temperature 120° C.). The basic formula is shown in Table 3:

[0070] Table 3 Basic formula of rubber in Application Example 2

[0071]

[0072] The vulcanization curves of zinc N,N′-methylcyclohexyl dithiocarbamate compounds, ZDBC compounds and ZDEC compounds are shown in Figure 4 , where 1 is ZDBC, 2 is N,N′-methylcyclohexyl zinc dithiocarbamate, and 3 is ZDEC; the vulcanization characteristic parameters are shown in Table 4:

[0073] Table 4 Vulcanization characteristic parameters of application example 2

[0074]

[0075] from Figure 4 It can be seen from Table 4 that when the same amount of N,N′-methylcyclohexyl zinc dithiocarbamate and vulcanization accelerators ZDBC and ZDEC are used, under the vulcanization condition of 120°C, the minimum torque, maximum torque, scorch time, positive vulcanization time and vulcanization rate are basically similar. N,N′-methylcyclohexyl zinc dithiocarbamate has similar vulcanization characteristics as vulcanization accelerators ZDBC and ZDEC.

[0076] The vulcanized rubber gloves prepared by using the zinc N,N′-methylcyclohexyl dithiocarbamate of the present invention as a vulcanization accelerator were sent to SGS for testing, and the nitrosamines and nitroso compounds were tested according to the EU standard EN 71-12:2016. NDELA, NDMA, NDEA, NDPA, NDiPA, NDBA, NDiBA, NDiNA, NMOR, NPIP, NDBzA, NMPhA, and NEPhA were not detected. The zinc N,N′-methylcyclohexyl dithiocarbamate of the present invention is used as a vulcanization accelerator, which is not easy to nitrosate during the processing of rubber products, and is not easy to produce nitrosamines with carcinogenic risks.

[0077] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A zinc N,N'-methylcyclohexyl dithiocarbamate, characterized in that: The structural formula is shown in Formula I:

2. The method for preparing zinc N,N'-methylcyclohexyldithiocarbamate according to claim 1, characterized in that: The following steps are involved: mixing carbon disulfide, zinc oxide, a surfactant and water to obtain a suspension; N-methylcyclohexylamine is added dropwise to the suspension to react, thereby obtaining zinc N,N'-methylcyclohexyldithiocarbamate.

3. The preparation method according to claim 2, characterized in that: The molar ratio of carbon disulfide to zinc oxide is 1-1.5:0.5-0.

6.

4. The preparation method according to claim 2, characterized in that: The surfactant includes one or more of dodecylphenol polyoxyethylene ether, Tween-20 and fatty alcohol polyoxyethylene ether.

5. The preparation method according to claim 2 or 4, characterized in that: The mass of the surfactant is 0.5% to 2% of the mass of zinc oxide.

6. The preparation method according to claim 2, characterized in that: The carbon disulfide, zinc oxide, surfactant and water are mixed under stirring conditions, the mixing temperature is 25-45° C., and the mixing time is 1-3 hours.

7. The preparation method according to claim 2 or 3, characterized in that: The molar ratio of the N-methylcyclohexylamine to carbon disulfide is 1:1 to 1.

5.

8. The preparation method according to claim 2, characterized in that: The reaction temperature is 80-90° C. and the reaction time is 3-6 hours.

9. Use of the zinc N,N'-methylcyclohexyldithiocarbamate according to claim 1 or the zinc N,N'-methylcyclohexyldithiocarbamate obtained by the preparation method according to any one of claims 2 to 8 as a vulcanization accelerator.

10. The use according to claim 9, characterized in that: The application is application in rubber vulcanization, the rubber includes natural rubber or synthetic rubber, and the mass ratio of the N,N'-methylcyclohexyl zinc dithiocarbamate to the rubber is 0.2-0.6:100.

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