Production method of rubber vulcanizing agent poly-p-tert-butylphenol disulfide

Abstract

The present invention belongs to the technical field of rubber vulcanizing agent production, and in particular to a production method of rubber vulcanizing agent poly-p-tert-butylphenol disulfide. The production method comprises the following steps: p-tert-butylphenol and n-heptane are put into a reactor, nitrogen is introduced for replacement, and stirring is heated to 80-100°C; then nitrogen is stopped, disulfur dichloride is pumped into the reactor through a feed distributor, and the reaction is stirred for 2-3h under the conditions of 80-100°C. After the reaction is completed, nitrogen is introduced again for replacement; then nitrogen is stopped and reduced pressure distillation is performed; finally, nitrogen is introduced into the reactor to restore normal pressure, and granulation is performed under the condition of continuous nitrogen introduction to obtain rubber vulcanizing agent poly-p-tert-butylphenol disulfide. The production method of the present invention is safe and efficient, and the prepared rubber vulcanizing agent has high sulfur content and high yield, and the solvent loss rate is low during the production process.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber vulcanizing agent production, and in particular relates to a method for producing rubber vulcanizing agent poly-p-tert-butylphenol disulfide. Background Art

[0002] Poly(p-tert-butylphenol disulfide) is a sulfur donor. When used as a rubber vulcanizer, it can improve the adhesion of vulcanized rubber, maintain high tensile strength and fatigue resistance, and has excellent heat aging resistance and anti-vulcanization reversion. Poly(p-tert-butylphenol disulfide) is light yellow to brown-black particles. It is generally made of p-tert-butylphenol and disulfur dichloride as the main raw materials, through condensation reaction, granulation and other steps, and the sulfur content is between 29.5-31.5wt.%.

[0003] At present, when producing alkylphenol disulfide vulcanizing agents in the industry, most of them need to add solvents, such as acetonitrile, nitromethane, trichloroethylene, petroleum ether, 200# solvent oil, etc. Some also need to add catalysts, and the preparation process is complicated and the cost is high.

[0004] For example, in US Pat. No. 4,877,902, 2,6-dialkylphenol and disulfur dichloride are used as raw materials, and nitroalkane and acetonitrile (or a combination thereof) are used as solvents to prepare 4,4'-polysulfide bis(2,6-dialkylphenol). This method uses a large amount of solvent and does not consider the recycling of the solvent. In addition, the reaction time is also long, up to 12 hours, which undoubtedly increases the production cost.

[0005] US Patent No. 3,968,062 discloses a method for preparing poly-p-tert-butylphenol disulfide, using p-tert-butylphenol and disulfur dichloride as raw materials, trichloroethylene (boiling point 87°C) as solvent, and the initial reaction temperature is 115-130°C, and gradually rises to 140-155°C as the reaction proceeds. In this method, the reaction temperature is relatively high, and the trichloroethylene gasified at high temperature and the hydrogen chloride gas generated by the reaction will carry disulfur dichloride out of the reaction system (the boiling point of disulfur dichloride is about 137°C), and the high temperature may cause the disulfur dichloride to decompose (disulfur dichloride may decompose when it reaches above 100°C, the higher the temperature, the greater the possibility of decomposition, and it will completely decompose at 300°C), and the solvent trichloroethylene used is a Class 1 carcinogen, which will endanger human health and environmental safety.

[0006] In view of the hazards of trichloroethane, patent CN102964282A discloses a method of using saturated alkanes (preferably petroleum ether) to replace trichloroethylene as a reaction solvent, wherein the weight ratio of p-tert-butylphenol to saturated alkanes (C5-10) is 1:0.10-0.15, and the reaction temperature is 100-140°C. This method also requires the reaction to be carried out at a relatively high temperature, and part of the disulfur dichloride will be gasified or decomposed, resulting in a large loss. In addition, petroleum ether has a low boiling point (generally 60-90°C), is easy to volatilize, and is not easy to condense during the reaction and distillation process, resulting in a large amount of solvent loss.

[0007] Patent CN104151551A uses a mixture of petroleum ether and 200# solvent oil (boiling range 140-200°C) as the reaction solvent for tert-butylphenol and disulfur dichloride, with a reaction temperature of 20-60°C. After the reaction is completed, the temperature is raised to above 160°C, and the solvent is evaporated under vacuum. The invention uses a mixed solvent to avoid the reaction material from heating up too quickly when the solvent is evaporated, causing the material to become viscous and bubbling. However, petroleum ether has a low boiling point and is not easy to condense, resulting in a large loss. The high-boiling point components in 200# solvent oil are difficult to evaporate and will remain in the product, reducing the sulfur content of the product. In addition, the reaction temperature of this method is too low, resulting in incomplete reaction of the raw materials. The remaining raw materials will decompose or react violently at the high temperature of vacuum distillation, which will deepen the color of the product and reduce the yield. Moreover, the viscosity of the material will increase in the later stage of the reaction, so this method requires the use of a large amount of solvent, resulting in increased energy consumption for solvent distillation.

[0008] More importantly, none of the above methods pays special attention to the safety issues in the production process. When using tert-butylphenol and disulfur dichloride as the main raw materials to produce poly-tert-butylphenol disulfide, the material may come into contact with iron through various channels, such as corrosion of pipelines and reactors, which will then produce iron sulfide, which is very easy to spontaneously combust, especially the iron sulfide (FeS / Fe 2 S 3 ), when in contact with oxygen at room temperature, it will rapidly oxidize and release heat, resulting in spontaneous combustion. If it encounters other combustibles, it may cause fire and explosion accidents. Therefore, in the industrial production process of poly(p-tert-butylphenol disulfide), it is also necessary to put the prevention of iron sulfide formation and spontaneous combustion in the first place. Summary of the invention

[0009] In view of the deficiencies in the prior art, the present invention aims to provide a method for producing a rubber vulcanizing agent poly-p-tert-butylphenol disulfide, which is safe and efficient, and the prepared rubber vulcanizing agent has a high sulfur content, a high yield, and a low solvent loss rate.

[0010] The production method of the rubber vulcanizing agent poly-p-tert-butylphenol disulfide of the present invention comprises the following steps:

[0011] (1) Feeding: Add 4-tert-butylphenol and n-heptane into a reactor, introduce nitrogen to replace, and then stir and heat to 60-70°C under the condition of continuous introduction of nitrogen;

[0012] (2) Reaction: Stop the nitrogen gas flow, inject disulfur dichloride into the reactor through the feed distributor, first react at 60-70°C for 1-1.5h, then heat to 95-105°C to continue the reaction, the total reaction time is 2-3h, after the reaction is completed, introduce nitrogen gas and continue stirring for 20-40min;

[0013] (3) Distillation: Stop the nitrogen flow, first perform atmospheric distillation at 110-120°C, then perform reduced pressure distillation at 130-140°C and pressure of -0.090 to -0.099 MPa;

[0014] (4) Granulation: nitrogen is introduced into the reactor to restore the pressure to normal, and then granulation is performed while maintaining the temperature at 130-150°C under the condition of continuous introduction of nitrogen to obtain the rubber vulcanizing agent poly-p-tert-butylphenol disulfide.

[0015] In the present invention, the molar ratio of p-tert-butylphenol to disulfur dichloride is 1:(1.0-1.02).

[0016] In the present invention, the mass ratio of p-tert-butylphenol to n-heptane is 1:(1.0-1.5).

[0017] The present invention adopts a single solvent n-heptane. Compared with the use of a mixed solvent, the problem of the change of the components of the mixed solvent does not need to be considered, and secondary distillation is not required. The distilled solvent can be directly reused, and the operation is simple. In the production process, n-heptane is used as a solvent on the one hand to dissolve p-tert-butylphenol, which is convenient for the reaction; on the other hand, as the reaction proceeds, the viscosity of the material gradually increases. Raising the reaction temperature is conducive to the reaction, but it will also cause part of the p-tert-butylphenol to sublimate. At this time, the reaction temperature is 95-105°C, and the n-heptane is in a slightly boiling state (the boiling point of n-heptane is 94-98°C). The n-heptane gas vaporized in the slightly boiling state rises in the reactor, and liquefies after contacting the reactor head and the sight glass with a slightly lower temperature, so that the sublimated and condensed p-tert-butylphenol can be dissolved and brought into the reaction system to continue to participate in the reaction, thereby preventing the sublimated p-tert-butylphenol from blocking the sight of the sight glass and improving the utilization rate of raw materials. In addition, the amount of n-heptane vaporized in the slightly boiling state is small, and the boiling range of n-heptane is higher than that of solvents such as petroleum ether. Gaseous n-heptane is easier to condense, which can reduce condensation energy consumption and n-heptane loss.

[0018] In step (1), the nitrogen replacement time is 20-30 minutes, and the flow rate is calculated according to the volume of the reactor. The volume of nitrogen introduced can be 1.6-2.4 times the volume of the reactor, in order to replace the air in the reactor. After the nitrogen replacement is completed, the flow rate of nitrogen is continuously introduced at 5-10L / min to prevent the outside air from entering the reactor.

[0019] In step (2), the feed distributor is a stainless steel tube lined with polytetrafluoroethylene material on both the inner and outer surfaces, the upper end of which is connected to the feed port of the reactor, the lower end is sealed and bent toward the center of the reactor, the bending angle is 90-120°, and discharge holes with a diameter of 2-3 mm are distributed below the bent part of the stainless steel tube. When adding disulfur dichloride to the reactor, the feed distributor is vertically inserted below the liquid level of the reactor, and disulfur dichloride is dispersed through the discharge port to below the liquid level of the reaction material under the pressure of the magnetic pump to participate in the reaction, which can reduce the loss of disulfur dichloride and improve the reaction to be more uniform and complete.

[0020] In step (2), there is no need to introduce nitrogen during the reaction process. The generated hydrogen chloride is continuously discharged from the reactor through the hydrogen chloride exhaust valve, and is condensed by the condenser and treated by the hydrogen chloride absorption system before being discharged.

[0021] The present invention first reacts at a temperature of 60-70°C, and then heats up to 95-105°C for reaction, thereby solving the problem of increased viscosity of the system in the late stage of the reaction, and appropriately raising the temperature is conducive to sufficient reaction, improving the product yield, and avoiding the loss of n-heptane and decomposition of disulfur dichloride caused by reacting under high temperature conditions for a long time, thereby improving the solvent recovery rate and raw material utilization rate. After the reaction is completed, continuing to stir for 20-40 minutes can make the raw material reaction more complete, and the flow rate of the nitrogen introduced is 5-10L / min, which can prevent air from entering the reactor and ensure the safety of the reaction process.

[0022] In step (3), atmospheric distillation is performed until almost no solvent is evaporated, and then vacuum distillation is performed. The purpose of performing distillation in two steps is, on the one hand, to fully evaporate the n-heptane to improve the solvent recovery rate, and on the other hand, atmospheric distillation can evaporate the residual HCl and most of the n-heptane. When vacuum distillation is performed, the remaining small amount of n-heptane will not cause serious bubbling of the material when it is evaporated, thereby ensuring smooth production.

[0023] In step (4), the material in the reactor gradually decreases during granulation. In order to prevent air from entering the reactor, nitrogen needs to be continuously introduced at a flow rate of 10-20 L / min.

[0024] Preferably, the method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide comprises the following steps:

[0025] (1) Feeding: Add tert-butylphenol and n-heptane in a mass ratio of 1: (1.0-1.5) into the reactor, open the nitrogen inlet valve and hydrogen chloride exhaust valve, and introduce nitrogen into the reactor for 20-30 minutes. The total volume of nitrogen introduced is 1.6-2.4 times the volume of the reactor. After replacing the air in the reactor, adjust the nitrogen flow rate to 5-10L / min, keep the outside air from entering the reactor, and stir to heat up to 60-70°C;

[0026] (2) Reaction: Close the nitrogen inlet valve, and inject the corresponding proportion of disulfur dichloride into the reactor through the feed distributor according to the molar ratio of p-tert-butylphenol to disulfur dichloride of 1: (1.0-1.02), first react at 60-70°C for 1-1.5h, then heat to 95-105°C to continue the reaction, and the total reaction time is 2-3h. The hydrogen chloride generated during the reaction is continuously discharged from the reactor through the hydrogen chloride exhaust valve, condensed by the condenser, and treated by the hydrogen chloride absorption system before being emptied. After the reaction is completed, open the nitrogen valve, introduce nitrogen at a flow rate of 5-10L / min, and continue stirring for 20-40min;

[0027] (3) Distillation: Stop the nitrogen flow, raise the temperature to 110-120°C for atmospheric distillation, evaporate the residual HCl and most of the n-heptane, then turn on the vacuum pump and perform reduced pressure distillation at a pressure of -0.090 to -0.099 MPa and a temperature of 130-140°C to completely evaporate the n-heptane;

[0028] (4) Granulation: After the distillation is completed, nitrogen is introduced into the reactor to restore the normal pressure, and then the nitrogen flow rate is adjusted to 10-20 L / min, and the temperature is maintained at 130-150°C to perform granulation to obtain the rubber vulcanizing agent poly-p-tert-butylphenol disulfide.

[0029] Considering that iron sulfide may be produced in the production process of the vulcanizing agent, which may bring potential safety hazards, the reactor used in the production process of the present invention is a glass-lined reactor, and a graphite condenser is used to condense the gas generated by the reaction and distillation, and a pipeline lined with polytetrafluoroethylene is used to transport the material. The entire production process (including reaction and granulation) is carried out in one reactor, which avoids material transfer, reduces the contact opportunity between the material and air and iron, simplifies the production steps, and improves safety.

[0030] During the operation of the present invention, nitrogen is introduced as a protective gas, so that the contact between the material and oxygen in the air is reduced, and the safety is improved. The produced rubber vulcanizing agent poly-p-tert-butylphenol disulfide is light yellow hemispherical particles, which are more suitable for the preparation of light-colored rubber and have a wider application range compared with dark brown products. In addition, the introduction of nitrogen can also prevent water vapor from entering the reaction kettle during the operation, thereby avoiding the loss of disulfur dichloride (disulfur dichloride is relatively active and is more likely to react with water than p-tert-butylphenol).

[0031] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide obtained by the production method of the invention is light yellow hemispherical particles, with a sulfur content of ≥30wt.% and a softening point of 90-95°C.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention adopts n-heptane with a boiling range of 94-98°C as the reaction solvent, and adopts a method of first reacting at 60-70°C for a period of time and then heating to 95-105°C for full reaction. On the one hand, the problem of increased viscosity of the system in the late stage of the reaction is solved. Appropriately increasing the temperature is conducive to full reaction and improving the product yield. At the same time, the loss of n-heptane and the decomposition of disulfur dichloride caused by long-term reaction under high temperature conditions are avoided, thereby improving the solvent recovery rate and raw material utilization rate. On the other hand, at the reaction temperature of 95-105°C in the late stage of the reaction, n-heptane is in a slightly boiling state, and the p-tert-butylphenol attached to the inner wall of the reactor and the sight glass after sublimation when the temperature is increased can be dissolved and refluxed into the reaction system, thereby improving the raw material utilization rate. In addition, the vaporization amount of n-heptane in the slightly boiling state is small, and it is easier to condense than low-boiling point solvents (such as petroleum ether, etc.), which can reduce the condensation energy consumption and the loss of n-heptane. The solvent loss rate in a single production process is less than 6%;

[0034] (2) The present invention distills off n-heptane and residual hydrogen chloride by first distilling at atmospheric pressure and then distilling at reduced pressure. On the one hand, the loss of n-heptane during the distillation process can be reduced, and the solvent recovery rate can be improved. On the other hand, the residual HCl and most of the n-heptane can be distilled off by atmospheric distillation. When performing reduced pressure distillation, the remaining small amount of n-heptane will not cause serious bubbling of the material during distillation, thereby ensuring smooth production.

[0035] (3) The present invention utilizes a feed distributor to disperse disulfur dichloride below the liquid surface of the reaction material to participate in the reaction, which can make the reaction more uniform and complete. At the same time, the reaction temperature is controlled below 105°C, shortening the high-temperature reaction time. After the reaction, the distillation is performed after a period of equilibrium, which can promote the full reaction of disulfur dichloride and reduce the thermal decomposition loss of disulfur dichloride, thereby reducing the excess rate of disulfur dichloride to less than 2%;

[0036] (4) The present invention avoids the use of iron equipment and provides nitrogen protection during the production process, thereby avoiding the generation of iron sulfide and the influence of oxygen and water vapor on the reaction materials, which not only improves production safety, but also the prepared rubber vulcanizing agent poly-p-tert-butylphenol disulfide is light yellow particles, which is more suitable for the preparation of light-colored rubber compared with the darker brown product and has a wider range of applications;

[0037] (5) The rubber vulcanizing agent poly-p-tert-butylphenol disulfide produced by the present invention has a sulfur content of ≥30wt.%, a softening point of 90-95°C, and when applied to rubber tire rubber, it can improve various properties of the rubber tire rubber, especially the resistance to hot air aging. DETAILED DESCRIPTION

[0038] The present invention is further described below with reference to the examples. The raw materials used in the examples, unless otherwise specified, are all commercially available conventional raw materials; the process methods used in the examples, unless otherwise specified, are all conventional methods in the art.

[0039] Some of the raw materials used in the examples are described as follows:

[0040] n-Heptane: boiling range 94-98°C, Liaoning Yufeng Chemical Co., Ltd.;

[0041] Petroleum ether: boiling range 60-90°C, density 0.7g / cm 3 , Liaoning Yufeng Chemical Co., Ltd.;

[0042] 200# solvent oil: boiling range 140-200℃, Liaoning Yufeng Chemical Co., Ltd.

[0043] The reactor used in the embodiment is a glass-lined reactor, the condenser used is made of graphite, and the pipes used for conveying materials are lined with polytetrafluoroethylene material.

[0044] The feed distributor used in the embodiment is a stainless steel tube lined with polytetrafluoroethylene material on both the inner and outer surfaces, the upper end of which is connected to the feed port of the reactor, the lower end is sealed and bent toward the center of the reactor, the bending angle is between 90-120° (120° is used in the embodiment), and discharge holes with a diameter of between 2-3mm (3mm is used in the embodiment) are distributed below the bent part of the stainless steel tube.

[0045] Example 1

[0046] The production method of the present invention is used to prepare the rubber vulcanizing agent poly-p-tert-butylphenol disulfide, which comprises the following steps:

[0047] (1) Feeding: Add 600 kg of p-tert-butylphenol and 600 kg of n-heptane into a 3000 L reactor, open the nitrogen inlet valve and the hydrogen chloride exhaust valve, and introduce nitrogen into the reactor at a flow rate of 160 L / min for 30 min to replace the air in the reactor. After replacing the air in the reactor, adjust the nitrogen flow rate to 10 L / min, and heat to 60 °C with stirring;

[0048] (2) Reaction: Close the nitrogen inlet valve, start the magnetic pump, and inject 539 kg of disulfur dichloride (the molar ratio of disulfur dichloride to tert-butylphenol is 1:1) into the reactor through the feed distributor. First, stir the reaction at 60°C for 1 hour, then raise the temperature to 100°C and continue the reaction for 1.5 hours. The hydrogen chloride generated by the reaction is continuously discharged from the reactor through the hydrogen chloride exhaust valve, condensed by the condenser, and treated by the hydrogen chloride absorption system before being emptied. After the reaction is completed, open the nitrogen valve and introduce nitrogen at a flow rate of 10 L / min, and continue stirring for 30 minutes;

[0049] (3) Distillation: Stop the nitrogen flow, raise the temperature to 120°C for atmospheric distillation, evaporate the residual HCl and most of the n-heptane, then turn on the vacuum pump and perform reduced pressure distillation at a pressure of -0.090 MPa and a temperature of 140°C to completely evaporate the n-heptane;

[0050] (4) Granulation: After the distillation is completed, nitrogen is introduced into the reactor to restore the normal pressure, and then the nitrogen flow rate is adjusted to 10 L / min, and the temperature is maintained at 150°C for granulation to obtain the rubber vulcanizing agent poly (p-tert-butylphenol disulfide).

[0051] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this example is light yellow hemispherical particles, with a sulfur content of 30.0wt.%, a softening point of 91.7°C, and a yield of 98.6%. During the production process, a total of 572.4kg of n-heptane was collected, and the solvent loss rate was 4.6%.

[0052] Example 2

[0053] The production method of the present invention is used to prepare the rubber vulcanizing agent poly-p-tert-butylphenol disulfide, which comprises the following steps:

[0054] (1) Feeding: 600 kg of p-tert-butylphenol and 720 kg of n-heptane were added to a 3000 L reactor. The nitrogen inlet valve and the hydrogen chloride exhaust valve were opened to introduce nitrogen into the reactor at a flow rate of 200 L / min for 30 min to replace the air in the reactor. The nitrogen flow rate was adjusted to 5 L / min and the temperature was raised to 70 °C with stirring.

[0055] (2) Reaction: Close the nitrogen inlet valve, start the magnetic pump, and inject 545 kg of disulfur dichloride (the molar ratio of disulfur dichloride to tert-butylphenol is 1.01:1) into the reactor through the feed distributor. First, stir and react at 70°C for 1.5 hours, then raise the temperature to 105°C and continue to react for 0.5 hours. The hydrogen chloride generated by the reaction is continuously discharged from the reactor through the hydrogen chloride exhaust valve, condensed by the condenser, and treated by the hydrogen chloride absorption system before being emptied. After the reaction is completed, open the nitrogen valve and introduce nitrogen at a flow rate of 5 L / min, and continue stirring for 40 minutes;

[0056] (3) Distillation: Stop the nitrogen flow, raise the temperature to 110°C for atmospheric distillation, evaporate the residual HCl and most of the n-heptane, then turn on the vacuum pump and perform reduced pressure distillation at a pressure of -0.099 MPa and a temperature of 130°C to completely evaporate the n-heptane;

[0057] (4) Granulation: After the distillation is completed, nitrogen is introduced into the reactor to restore the normal pressure, and then the nitrogen flow rate is adjusted to 5 L / min, and the temperature is maintained at 150°C for granulation to obtain the rubber vulcanizing agent poly (p-tert-butylphenol disulfide).

[0058] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this example is light yellow hemispherical particles, with a sulfur content of 30.1wt.%, a softening point of 93.2°C, and a yield of 98.9%. A total of 683.3kg of n-heptane was collected during the production process, and the solvent loss rate was 5.1%.

[0059] Example 3

[0060] The production method of the present invention is used to prepare the rubber vulcanizing agent poly-p-tert-butylphenol disulfide, which comprises the following steps:

[0061] (1) Feeding: 600 kg of p-tert-butylphenol and 780 kg of n-heptane were added to a 3000 L reactor. The nitrogen inlet valve and the hydrogen chloride exhaust valve were opened to introduce nitrogen into the reactor at a flow rate of 240 L / min for 30 min to replace the air in the reactor. The nitrogen flow rate was adjusted to 8 L / min and the temperature was raised to 65 °C with stirring.

[0062] (2) Reaction: Close the nitrogen inlet valve, start the magnetic pump, and inject 547.5 kg of disulfur dichloride (the molar ratio of disulfur dichloride to tert-butylphenol is 1.015:1) into the reactor through the feed distributor. First, stir and react at 65°C for 1.5 hours, then raise the temperature to 95°C and continue to react for 1.5 hours. The hydrogen chloride generated by the reaction is continuously discharged from the reactor through the hydrogen chloride exhaust valve, condensed by the condenser, and treated by the hydrogen chloride absorption system before being emptied. After the reaction is completed, open the nitrogen valve and introduce nitrogen at a flow rate of 8 L / min, and continue stirring for 30 minutes;

[0063] (3) Distillation: Stop the nitrogen flow, raise the temperature to 115°C for atmospheric distillation, evaporate the residual HCl and most of the n-heptane, then turn on the vacuum pump and perform reduced pressure distillation at a pressure of -0.095 MPa and a temperature of 125°C to completely evaporate the n-heptane;

[0064] (4) Granulation: After the distillation is completed, nitrogen is introduced into the reactor to restore the normal pressure, and then the nitrogen flow rate is adjusted to 8 L / min, and the temperature is maintained at 140°C for granulation to obtain the rubber vulcanizing agent poly (p-tert-butylphenol disulfide).

[0065] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this example is light yellow hemispherical particles, with a sulfur content of 30.1wt.%, a softening point of 93.4°C, and a yield of 99.0%. A total of 738.7kg of n-heptane was collected during the production process, and the solvent loss rate was 5.3%.

[0066] Example 4

[0067] The production method of the present invention is used to prepare the rubber vulcanizing agent poly-p-tert-butylphenol disulfide, which comprises the following steps:

[0068] (1) Feeding: 600 kg of p-tert-butylphenol and 900 kg of n-heptane were added to a 3000 L reactor. The nitrogen inlet valve and the hydrogen chloride exhaust valve were opened to introduce nitrogen into the reactor at a flow rate of 240 L / min for 20 min to replace the air in the reactor. The nitrogen flow rate was adjusted to 10 L / min and the temperature was raised to 70 °C with stirring.

[0069] (2) Reaction: Close the nitrogen inlet valve, start the magnetic pump, and inject 550 kg of disulfur dichloride (the molar ratio of disulfur dichloride to tert-butylphenol is 1.02:1) into the reactor through the feed distributor. First, stir and react at 70°C for 1 hour, then raise the temperature to 105°C and continue to react for 1 hour. The hydrogen chloride generated by the reaction is continuously discharged from the reactor through the hydrogen chloride exhaust valve, condensed by the condenser, and treated by the hydrogen chloride absorption system before being emptied. After the reaction is completed, open the nitrogen valve and introduce nitrogen at a flow rate of 10 L / min, and continue stirring for 20 minutes;

[0070] (3) Distillation: Stop the nitrogen flow, raise the temperature to 110°C for atmospheric distillation, evaporate the residual HCl and most of the n-heptane, then turn on the vacuum pump and perform reduced pressure distillation at a pressure of -0.099 MPa and a temperature of 130°C to completely evaporate the n-heptane;

[0071] (4) Granulation: After the distillation is completed, nitrogen is introduced into the reactor to restore the normal pressure, and then the nitrogen flow rate is adjusted to 10 L / min, and the temperature is maintained at 130°C for granulation to obtain the rubber vulcanizing agent poly (p-tert-butylphenol disulfide).

[0072] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this example is light yellow hemispherical particles, with a sulfur content of 30.2wt.%, a softening point of 93.7°C, and a yield of 99.2%. A total of 848.7kg of n-heptane was collected during the production process, and the solvent loss rate was 5.7%.

[0073] Comparative Example 1

[0074] In this comparative example, the rubber vulcanizing agent poly-p-tert-butylphenol disulfide was prepared according to the method disclosed in Example 1 of patent CN104151551 A, as follows:

[0075] Add 100g of p-tert-butylphenol and 200g of a mixed solvent (160g of petroleum ether and 40g of 200# solvent oil) into a 500ml four-necked flask, install an agitator, a reflux device, a constant pressure dropping funnel, and a thermometer, and cool the reflux device with tap water. Add 95g of disulfur dichloride (the molar ratio of disulfur dichloride to p-tert-butylphenol is about 1.05:1) into the constant pressure dropping funnel, raise the temperature to 50°C while stirring, slowly drop the disulfur dichloride into the flask within 2h, and continue stirring at low temperature for 1h; change to a vacuum distillation device, start vacuuming when the temperature rises to 170°C, continue to raise the temperature to 180°C, and distill under reduced pressure until no solvent is evaporated, collect the evaporated solvent, and pour the material into a clean porcelain tray while hot for cooling, so as to obtain the rubber vulcanizing agent poly-p-tert-butylphenol disulfide.

[0076] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this comparative example is dark brown-red particles with a sulfur content of 27.8wt.%, a softening point of 88.4°C, and a yield of 94.1%. During the preparation process, 162.6g of mixed solvent (petroleum ether and 200# solvent oil) was collected, and the solvent loss rate was 18.7%.

[0077] Compared with the present invention, the rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared by the method has a lower sulfur content and yield, and a darker color. On the one hand, it is because it uses high-boiling point 200# solvent oil as a solvent, and 200# solvent oil is difficult to be completely evaporated during the distillation process, and a part of the solvent will remain in the product, resulting in a reduction in sulfur content; on the other hand, it is because the reaction temperature of the method is relatively low, and the raw materials are difficult to react completely at a relatively low reaction temperature, and the distillation temperature in the later stage is too high. During the distillation process, the remaining disulfur dichloride will undergo thermal decomposition, and p-tert-butylphenol will also be evaporated with the solvent, resulting in a reduction in product yield, and the excessively high temperature during distillation may also cause some side reactions, which is also the reason why the product color is darker. In addition, the solvent loss rate of the method is much higher than that of the present invention, because the proportion of low-boiling petroleum ether in the mixed solvent used is relatively large, and petroleum ether has a low boiling point, is highly volatile, and is difficult to condense, and is easily lost during the reaction process. Therefore, the solvent addition ratio of the method is also higher than that of the present invention.

[0078] Comparative Example 2

[0079] This comparative example adopts the method disclosed in Example 3 of patent CN102964282A to prepare rubber vulcanizing agent poly-p-tert-butylphenol disulfide, as follows:

[0080] 150g of p-tert-butylphenol and 150ml of petroleum ether (105g) were added to a 500ml four-necked flask, and a stirrer, a reflux device, a constant pressure dropping funnel, and a thermometer were installed. The reflux device was cooled with tap water. 162g of disulfur dichloride (the molar ratio of disulfur dichloride to p-tert-butylphenol was 1.2:1) was added to the constant pressure dropping funnel. The temperature was raised to 100°C under stirring. The disulfur dichloride was added dropwise to the flask within 1.5h for reaction. After the addition was completed, stirring was continued until no reaction gas was released. During the reaction, the temperature was gradually raised to 140°C. The hydrogen chloride produced by the reaction was absorbed by a dilute alkali solution after passing through a reflux condenser. After the reaction was completed, the reduced pressure distillation was carried out until no solvent was evaporated. The evaporated solvent was collected to obtain a brown viscous liquid, which was released while hot and granulated to obtain a brown solid, which was the rubber vulcanizing agent poly-p-tert-butylphenol disulfide.

[0081] The rubber vulcanizing agent poly-p-tert-butylphenol disulfide prepared in this comparative example is dark brown particles with a sulfur content of 28.5wt.%, a softening point of 89.5°C, and a yield of 98.2%. During the preparation process, 65.8g of petroleum ether was collected, and the solvent loss rate was 37.3%.

[0082] Compared with the present invention, this method uses petroleum ether as a solvent. Since petroleum ether has a low boiling point, is highly volatile, and is difficult to condense, it is easily lost during the reaction process, resulting in a much higher solvent loss rate than the present invention. In addition, the reaction temperature of this method is always kept at a relatively high temperature, disulfur dichloride is prone to thermal decomposition, and at a reaction temperature of 140° C., some side reactions may occur, resulting in a lower sulfur content and darker color of the product.

[0083] From the comparison of the preparation methods of the embodiments and comparative examples 1-2, it can be seen that the vulcanizing agent obtained by the preparation method of the present invention is lighter in color and can be used as an additive for light-colored rubber, and its application range is wider; and the sulfur content is relatively high, which helps to improve its vulcanization performance; in addition, the solvent recovery rate is greatly improved during the preparation process, the excess rate of disulfur dichloride is reduced, the raw material utilization rate is improved, and the production cost is significantly reduced.

[0084] Taking Example 3 as an example, the rubber vulcanizing agent poly-p-tert-butylphenol disulfide samples prepared in Example 3 and Comparative Examples 1-2 were added to the rubber under the same formula and the same conditions, and after vulcanization at 150°C for 30 minutes, various properties were tested, and after hot air aging at 100°C for 48 hours, various properties were tested again. Among them, the tensile stress, tensile strength, and elongation at break were tested with reference to the standard GB / T 528-2009, the tear strength was tested with reference to the standard GB∕T 529-2008, and the rebound rate was tested with reference to the standard GB / T 1681-2009. The test results are shown in Table 1-2.

[0085] Table 1 Test results of vulcanized rubber properties

[0086]

[0087] Table 2 Test results of vulcanized rubber properties after hot air aging

[0088]

[0089] It can be seen from Table 1-2 that compared with the rubber vulcanizer prepared in Comparative Example 1-2, the rubber vulcanizer of the present invention prepared under the same conditions has a smaller decrease rate in tensile strength and elongation at break after hot air aging, which indicates that the rubber vulcanizer prepared in the present invention has better resistance to hot air aging.

Claims

1. A method for producing a rubber vulcanizing agent poly-p-tert-butylphenol disulfide, characterized in that: The following steps are involved: (1) Feeding: Add 4-tert-butylphenol and n-heptane into a reactor, introduce nitrogen to replace, and then stir and heat to 60-70°C under the condition of continuous introduction of nitrogen; (2) Reaction: Stop the nitrogen gas flow, inject disulfur dichloride into the reactor through the feed distributor, first react at 60-70°C for 1-1.5h, then heat to 95-105°C to continue the reaction, the total reaction time is 2-3h, after the reaction is completed, introduce nitrogen gas and continue stirring for 20-40min; (3) Distillation: Stop the nitrogen flow, first perform atmospheric distillation at 110-120°C, then perform reduced pressure distillation at 130-140°C and pressure of -0.090 to -0.099 MPa; (4) Granulation: nitrogen is introduced into the reaction kettle to restore the normal pressure, and then granulation is performed while maintaining the temperature at 130-150° C. under the condition of continuous introduction of nitrogen to obtain the rubber vulcanizing agent poly-p-tert-butylphenol disulfide; Among them, the reactor used in the production process is a glass-lined reactor; a graphite condenser is used in the production process to condense the gases generated by the reaction and distillation; and a pipe lined with polytetrafluoroethylene material is used to transport materials in the production process.

2. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: The molar ratio of p-tert-butylphenol to disulfur dichloride is 1:(1.0-1.02).

3. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: The mass ratio of p-tert-butylphenol to n-heptane is 1:(1.0-1.5).

4. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: In step (1), the nitrogen replacement time is 20-30 min, and the volume of nitrogen introduced during the nitrogen replacement is 1.6-2.4 times the volume of the reactor.

5. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: After nitrogen replacement is completed, nitrogen is continuously introduced at a flow rate of 5-10 L / min.

6. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: In step (2), the feed distributor is a stainless steel tube with polytetrafluoroethylene lined on both the inner and outer surfaces, the upper end of which is connected to the feed port of the reactor, the lower end is sealed and bent toward the center of the reactor, the bending angle is 90-120°, and discharge holes with a diameter of 2-3 mm are distributed below the bent part of the stainless steel tube.

7. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: In step (2), after the reaction is completed, nitrogen is introduced at a flow rate of 5-10 L / min.

8. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: In step (4), the nitrogen flow rate is 10-20 L / min.

9. The method for producing the rubber vulcanizing agent poly-p-tert-butylphenol disulfide according to claim 1, characterized in that: The obtained rubber vulcanizing agent poly-p-tert-butylphenol disulfide is light yellow hemispherical particles, with a sulfur content of ≥30wt.%, and a softening point of 90-95°C.

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