Preparation method and application of supported tetrabutylthiuram disulfide

Abstract

The invention relates to a preparation method and application of supported tetrabutylthiuram disulfide. The preparation method comprises the following steps: firstly, uniformly mixing water and carbon disulfide, and then sequentially adding di-n-butylamine and hydrogen peroxide into the mixed solution to react; after the reaction is finished, dilute acid is added for washing, an oil phase and a water phase are separated, water in the oil phase is removed through a 4A molecular sieve, finally, the oil phase is mixed with a proper amount of nano silicon dioxide, and the supported tetrabutylthiuram disulfide is obtained. The supported tetrabutylthiuram disulfide prepared by the method does not generate high-salt waste liquid, the product appearance is faint yellow, the amine residue is less than or equal to 0.1%, the moisture is less than or equal to 0.3%, the yield is more than or equal to 99.0%, and the purity is more than or equal to 99.0%; after the shape is changed, the product is difficult to decompose in storage and transportation processes; the dispersion is uniform in rubber product processing, and the performance requirements of light-color or thin products can be met; and the method can be carried out on conventional equipment, adopts low-temperature reaction, and is high in safety.

Description

Technical Field

[0001] The invention relates to the field of rubber vulcanization accelerator preparation and rubber product processing, and specifically refers to a preparation method and application of supported tetrabutylthiuram disulfide. Background Art

[0002] Vulcanization accelerator is an essential chemical substance in the rubber production process. It can not only increase the vulcanization speed of rubber and improve the performance of rubber, but also affect the aging performance of rubber, so it is widely used in rubber production. Compared with other tetraalkylthiuram disulfide vulcanization accelerators, tetrabutylthiuram disulfide vulcanization accelerators have the characteristics of no frosting, no pollution and good dispersion performance. However, with the development of society and the advancement of science and technology, the tetrabutylthiuram disulfide vulcanization accelerator prepared by traditional technology cannot meet the needs of the modern rubber industry.

[0003] At present, there are mainly the following routes for the preparation of tetrabutylthiuram disulfide:

[0004] The patent (CN 108610272 A) discloses a micro-reaction method for continuously synthesizing tetraalkylthiuram disulfide. The method uses a micro-mixer and a micro-reactor connected in series to sequentially complete the three processes of secondary amine-NaOH solution mixing, CS2-secondary amine condensation reaction and sodium dithiocarbamate oxidation reaction. The micro-reaction device efficiently mixes the reaction materials to avoid the occurrence of side reactions such as excessive oxidation. The production efficiency and product stability are improved through the series integrated operation mode. The method can be used to produce a variety of thiuram vulcanization additives such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabutylthiuram disulfide.

[0005] Related literature reports that the synthesis technology of tetrabutylthiuram disulfide generally adopts the acid-base method for preparation. First, dibutylamine and liquid alkali are added dropwise with carbon disulfide to obtain a solution containing sodium dibutyldithiocarbamate, and then sulfuric acid and hydrogen peroxide are added dropwise to the obtained solution containing sodium dibutyldithiocarbamate. After stirring for reaction, the oil phase is separated and tetrabutylthiuram disulfide is obtained. There is also an improved process, which uses dibutylamine, carbon disulfide and sodium carbonate as raw materials, reacts in water at a temperature below -10 to -15°C to generate sodium dibutyldithiocarbamate, and then reacts with potassium ferrocyanide at 0°C to prepare tetrabutylthiuram disulfide.

[0007] The above methods generally have the problem of generating a large amount of high-salt waste liquid during industrialization, such as waste liquid containing sodium sulfate. The subsequent sodium sulfate wastewater treatment often causes serious environmental pollution. In addition, the yield and purity of tetrabutylthiuram disulfide prepared by the existing acid-base method are both low, and the appearance color is also dark, often dark brown oily liquid, and white or light-colored rubber products cannot be further prepared.

[0008] The patent (CN 110950790 A) discloses a method for preparing tetrabutylthiuram disulfide, a rubber vulcanization accelerator, and the specific reaction steps are as follows:

[0009] ① Add 1200L of pure water and 400kg of di-n-butylamine into the reaction container in sequence, stir the solvent to mix evenly, and obtain a di-n-butylamine aqueous solution;

[0010] ② Then adjust the temperature to 30° C. and add 243 kg of carbon disulfide dropwise to the di-n-butylamine aqueous solution obtained in step ①. The addition is completed over 2.5 hours. After the addition of carbon disulfide is completed, continue to stir and react at the same temperature for 2 hours to obtain a solution containing di-n-butyldithiocarbamic acid;

[0011] ③ Then adjust the temperature to 20° C. and add 338.1 kg of 16.5 wt% hydrogen peroxide to the solution containing di-n-butyl dithiocarbamic acid obtained in step ②. The addition is completed over 3.0 hours. After the addition of hydrogen peroxide is completed, continue to stir the reaction at the same temperature for 2 hours, and then stand to separate the oil phase;

[0012] ④ The oil phase after standing and separation in step ③ was transferred into a distillation kettle, heated to 80°C and subjected to reduced pressure distillation for 2.5h to remove the solvent water in the oil phase to obtain tetrabutylthiuram disulfide, a rubber vulcanization accelerator;

[0013] This preparation method is currently the most commonly used route for producing tetrabutylthiuram disulfide. The disadvantages of this method are that in step ④, the oil phase is transferred to a distillation kettle, heated to 80°C and distilled under reduced pressure for 2.5 hours, resulting in lower product yield and purity, darker color, high residual di-n-butylamine in the product, and high water content; during the storage and transportation of the product, the decomposition purity decreases; it cannot be evenly dispersed during rubber processing, resulting in partial over-sulfurization or under-sulfurization, and the product cannot meet the requirements of light-colored and thin products.

[0014] In view of the above problems, the present invention discloses a preparation method and application of supported tetrabutylthiuram disulfide. The supported tetrabutylthiuram disulfide prepared by the method does not produce salt-containing waste liquid, has a light yellow appearance, low amine residue, moisture ≤0.3%, a yield ≥99.0%, and a purity ≥99.0%;

[0015] After the shape is changed, the product is difficult to decompose during storage and transportation; it is evenly dispersed during rubber product processing and can meet the requirements of light-colored and thin products. Summary of the invention

[0016] The purpose of the present invention is to address the technical defects existing in the prior art, and the present invention provides a method for preparing supported tetrabutylthiuram disulfide.

[0017] The present invention is implemented by the following technical solutions:

[0018] A preparation method and application of supported tetrabutylthiuram disulfide, characterized by comprising the following steps:

[0019] (1) Water and carbon disulfide are added into the reactor in sequence, the temperature is controlled at 10-20°C, and stirred for 10-15 minutes;

[0020] (2) Slowly add di-n-butylamine at 10-20°C, and then control the temperature at 10-20°C to react for 0.5-1h;

[0021] (3) Slowly add hydrogen peroxide at 10-20°C, and then control the temperature at 10-20°C to react for 2-3 hours;

[0022] (4) Separate the water layer and wash the oil phase with dilute acid;

[0023] (5) separating the oil phase from the water phase, and removing water from the oil phase using a 4A molecular sieve;

[0024] (6) The oil phase is mixed with an appropriate amount of silicon dioxide to obtain a supported tetrabutylthiuram disulfide compound.

[0025] Preferably, the molar ratio of di-n-butylamine, carbon disulfide and hydrogen peroxide is 1.0:0.98 to 1.0:0.5 to 0.55.

[0026] Preferably, the hydrogen peroxide is a 10% to 15% aqueous solution.

[0027] Preferably, the mass of the appropriate amount of silicon dioxide is 28% to 32% of the mass of liquid tetrabutylthiuram disulfide; and the particle size of the silicon dioxide is 10 to 50 nm.

[0028] The supported tetrabutylthiuram disulfide compound prepared by the invention is used as a vulcanization accelerator in light-colored or thin rubber products, such as rubber bands, transparent rubber balls and the like.

[0030] The present invention has the following beneficial effects:

[0031] The supported tetrabutylthiuram disulfide prepared by the method does not generate high-salt waste liquid, the product has a light yellow appearance, amine residue ≤0.1%, water ≤0.3%, yield ≥99.0%, and purity ≥99.0%. After the product changes its form, it is difficult to decompose during storage and transportation. It is evenly dispersed during rubber product processing and can meet the performance requirements of light-colored or thin products. In addition, the method can be carried out on conventional equipment, adopts low-temperature reaction, and has high safety.

[0032] (1) It was first proposed to react dibutylamine with carbon disulfide and hydrogen peroxide under low temperature conditions (control the reaction temperature at 10-20°C), and then use a water absorbent to remove the water in the liquid product. Carbon disulfide is flammable and has a wide explosion range, and low temperature is conducive to safe operation; secondary amines are easily oxidized to reddish-brown oxides at high temperatures, and low temperatures are conducive to reducing the formation of secondary amine oxides.

[0033] (2) Use dilute acid washing to remove the dibutylamine that has not participated in the reaction.

[0034] (3) Liquid products are mixed with silica to form solid products, which are difficult to decompose during transportation and storage.

[0035] (4) The preparation process is simple, the process is simple, the operation is safe, and it has good performance when applied to light-colored or thin rubber products. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the curing characteristic curing curve of the compound rubber of Example 1 in Table 2 at 140°C;

[0037] Figure 2 is the vulcanization characteristic vulcanization curve at 140°C of the compound rubber of Example 2 in Table 2;

[0038] Figure 3 It is the vulcanization characteristic vulcanization curve of the compound rubber of the comparative example 1 in Table 2 at 140°C. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail in the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0042] At room temperature, 200.0g of water and 29.6g (wt 97.5%) of carbon disulfide were sequentially added into a four-necked flask with a condenser, cooled to 10-20°C, and stirred at this temperature for 15min; 50.0g of di-n-butylamine (wt 99.0%) was added dropwise at a temperature of 10-20°C, and stirred at 10-20°C for 1h; 53.1g of hydrogen peroxide (wt 13.0%) was added dropwise at a temperature of 10-20°C, and stirred for 2.5h after the addition was completed; The material was transferred to a separating funnel to separate the water layer, the oil layer was washed twice with an appropriate amount of dilute acid (wt 0.8%), and then washed with water until the pH value was 6-7; the oil phase was transferred to a beaker, 5-10 particles of 4A molecular sieve were added, and the mixture was placed on a vibration table and vibrated for 2-3 hours to remove water; the molecular sieve was removed to obtain 76.6 g of liquid tetrabutylthiuram disulfide; the yield of tetrabutylthiuram disulfide was 99.1%, the purity detected by chromatography was 99.2%, the purity detected by chromatography was 0.09% of the residual amine, and the water content was 0.27%.

[0043] Example 2

[0044] At room temperature, 200.0g water and 29.6g (wt 97.5%) carbon disulfide were sequentially added into a four-necked flask with a condenser, cooled to 10-20°C, and stirred at this temperature for 15min; 50.0g di-n-butylamine (wt 99.0%) was added dropwise at a temperature of 10-20°C, and stirred at 10-20°C for 1h after completion; 53.1g hydrogen peroxide (wt 11.0%) was added dropwise at a temperature of 10-20°C, and stirred for 2.5h after completion of the addition; the material was transferred to a separating funnel to separate the water layer, and the oil layer was treated with an appropriate amount of dilute acid (wt 0.8%). Wash twice, and then wash with water until the pH value is 6-7; transfer the oil phase to a beaker, add 5-10 4A molecular sieves, and place it on a vibration table to vibrate for 2-3 hours to remove water; remove the molecular sieve to obtain 76.9g of liquid tetrabutylthiuram disulfide; the yield of tetrabutylthiuram disulfide is 99.5%, the purity detected by chromatography is 99.3%, the amine residue detected by chromatography is 0.07%, and the water content is 0.25%; add 33.0g of silicon dioxide with a particle size of 10-50nm to 76.9g of liquid tetrabutylthiuram disulfide and mix them evenly to obtain supported tetrabutylthiuram disulfide.

[0045] Comparative Example 1

[0046] At room temperature, 120.0g of water and 40.0g of di-n-butylamine (wt 99%) aqueous solution were sequentially added into a four-necked flask with a condenser, the temperature was 30±1°C, and the mixture was stirred at this temperature for 1h; 24.8g of carbon disulfide (wt 97.5%) was added dropwise at a temperature of 30±1°C, and the mixture was stirred and reacted at 30±1°C for 2h after completion; the temperature was lowered by 20±1°C, 33.8g of hydrogen peroxide (wt 16.5%) was added dropwise, and the mixture was stirred and reacted at 20±1°C for 2h after completion; the water layer was separated and the oil phase was distilled at 80°C under reduced pressure of 0.09-0.095MPa for 2.5h to obtain 58.8g of tetrabutylthiuram disulfide; the yield of tetrabutylthiuram disulfide was 95.1%, the purity detected by liquid phase was 97.9%, the purity detected by chromatography was 1.3% of amine residue, and the water content was 0.75%;

[0047] This comparative example was repeatedly tested according to the preparation method disclosed in the patent (CN 110950790A), and the highest product yield was 95.1%. The main reason for the low yield and purity was the hydrolysis of tetrabutylthiuram disulfide during the vacuum distillation at 80°C.

[0048] The samples prepared by the above three methods were numbered as sample 1, sample 2, and sample 3, respectively, and placed in a constant temperature and humidity oven at a temperature of 50±2°C and a humidity of 30% to 33%. The purity and amine residue were tested at 20d, 40d, 60d, 80d, and 100d, respectively. The results are shown in Table 1:

[0049] Table 1

[0050]

[0051]

[0052] As can be seen from Table 1, the stability of the supported tetrabutylthiuram disulfide of Example 2 is better than that of the non-supported tetrabutylthiuram disulfide of Example 1 and the tetrabutylthiuram disulfide prepared in Comparative Example 1. The product of Example 1 is difficult to decompose during storage and transportation.

[0053] The products of Example 1, Example 2 and Comparative Example 1 were respectively prepared into rubber mixtures according to the basic formula of natural rubber in Table 2, and then the vulcanization characteristics at 140°C were tested. Figure 1-3 The dispersion uniformity of the accelerator is quantified by calculating the dispersion degree (standard deviation) of the scorch time (ts1), the positive vulcanization time (tc90), and the vulcanization index (CRI1) in each group of sample results. As shown in Table 3, the dispersion degree of Example 2 is significantly smaller than that of Example 1 and Comparative Example 1, indicating that the dispersion of the sample prepared in Example 2 in the rubber material is better than that of Example 1 and Comparative Example 1. Figure 1 , Figure 2 , Figure 3The standard deviation of each test result is calculated, which is also the data corresponding to "σ(N)" in the figure. The specific process is that after preparing the mixed rubber for each sample, the rubber material at 4 different positions is taken to test the vulcanization characteristics, and then the standard deviation of the corresponding data results of the scorch time (ts1), positive vulcanization time (tc90), and vulcanization index (CRI1) in the 4 test results is calculated.

[0054] Table 2

[0055]

[0056] Table 3

[0057]

[0058] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing supported tetrabutylthiuram disulfide, characterized in that: The following steps are involved: (1) Water and carbon disulfide are added into the reactor in sequence, the temperature is controlled at 10-20°C, and stirred for 10-15 minutes; (2) Slowly add di-n-butylamine at 10-20°C, and then control the temperature at 10-20°C to react for 0.5-1h; (3) Slowly add hydrogen peroxide at 10-20°C, and then control the temperature at 10-20°C to react for 2-3 hours; (4) separation of the oil phase and the water phase; (5) obtaining liquid tetrabutylthiuram disulfide in the oil phase; (6) Mixing liquid tetrabutylthiuram disulfide with silicon dioxide to obtain a supported tetrabutylthiuram disulfide compound.

2. The method for preparing a supported tetrabutylthiuram disulfide according to claim 1, characterized in that: The molar ratio of di-n-butylamine, carbon disulfide and hydrogen peroxide is 1.0:0.98 to 1.0:0.5 to 0.55; in step (5), the oil phase is washed with dilute acid to remove the di-n-butylamine that has not participated in the reaction, and then washed with water to remove the acid.

3. The method for preparing a supported tetrabutylthiuram disulfide according to claim 1, characterized in that: The hydrogen peroxide is a 10% to 15% aqueous solution.

4. The method for preparing a supported tetrabutylthiuram disulfide according to claim 1, characterized in that: The mass of the silicon dioxide is 28% to 32% of the mass of liquid tetrabutylthiuram disulfide; and the particle size of the silicon dioxide is 10 to 50 nm.

5. The supported liquid tetrabutylthiuram disulfide prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The amine residue in the tetrabutylthiuram disulfide compound is ≤0.1%, the water content is ≤0.3%, the yield is ≥99.0%, and the purity is ≥99.0%.

6. Use of the supported tetrabutylthiuram disulfide according to claim 5 as a vulcanization accelerator in light-colored or thin rubber products.

7. A rubber composition using the supported tetrabutylthiuram disulfide as claimed in claim 5 as a vulcanization accelerator, characterized in that: The dispersion of scorch time (ts1), positive cure time (tc90) and vulcanization index (CRI1) is lower than that of the rubber composition with non-supported tetrabutylthiuram disulfide as vulcanization accelerator.

8. The rubber composition according to claim 7, characterized in that The rubber composition comprises 100 g of NR, 5 g of zinc oxide, 2.5 g of sulfur, 1 g of stearic acid and 1 g of the supported tetrabutylthiuram disulfide.

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