Preparation method for increasing bulk density of rubber accelerator TMTD

Abstract

The invention belongs to the technical field of rubber vulcanization accelerator TMTD production, and relates to a preparation method for increasing the bulk density of a rubber accelerator TMTD. Water, dimethylamine and carbon disulfide are fully and uniformly mixed and then react. Dropwise adding the liquid alkali solution when the pH value is 7.9-8.1, dropwise adding hydrogen peroxide to carry out oxidation reaction, and adding phosphate when the pH value reaches 5.9-6.1. And continuously dropwise adding hydrogen peroxide until the pH value reaches 1-2, continuously stirring, filtering, washing, adding deionized water and a defoaming agent, filtering, and drying to obtain a dry product of the rubber accelerator TMTD. The rubber accelerator TMTD synthesized by the method provided by the invention is a white crystal in appearance, large in bulk density, stable in product quality and resistant to storage, and the process conforms to the production concepts of green production and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber vulcanization accelerator TMTD production and relates to a preparation method for increasing the bulk density of the rubber accelerator TMTD. Background Art

[0002] At present, the rubber vulcanization accelerator TMTD is mostly synthesized by the chlorine method. After the oxidation in the oxidation kettle, the product mostly floats or suspends above the liquid, which makes it impossible to stir evenly during the production process, resulting in quality problems in the product. In addition, there are also problems of difficult and time-consuming material transfer during the material transfer process. In the subsequent packaging, due to the low bulk density of the product, the product occupies a large space. There is also a clumping problem caused by static electricity during storage, which seriously affects the shelf life of the product. At the same time, due to the low bulk density, the dispersibility of the product is relatively poor. When preparing the pre-dispersion TT-80, it cannot form a good agglomeration during the mixing process, the granulation speed is slow during granulation, and the cut surface of the granules is rough, which affects the use effect. Summary of the invention

[0003] Aiming at the problems existing in the production and use of the traditional rubber vulcanization accelerator TMTD, the invention proposes a novel preparation method for increasing the bulk density of the rubber accelerator TMTD.

[0004] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions: A preparation method for increasing the bulk density of rubber accelerator TMTD comprises the following steps: (1) Add dimethylamine solution and carbon disulfide into the static mixer in sequence, keep them for a sufficient residence time, mix them thoroughly and then add them into the first reactor for reaction.

[0005] (2) Under stirring, add the liquid alkali solution dropwise to the first reactor, use a pH online monitor to detect the pH value, stop adding dropwise when the pH value is 7.9-8.1, and obtain a dimethyl sodium disulfide formate solution. Preferably, the dimethyl sodium disulfide formate solution has a straw yellow-green appearance and a specific gravity of 1.070 g / ml.

[0006] (3) Under stirring, hydrogen peroxide is added dropwise to the sodium dimethyl disulfide formate solution to carry out an oxidation reaction, and a pH online monitor is used to detect the pH value during the process of adding hydrogen peroxide.

[0007] (4) When the pH value reaches 5.9-6.1, add phosphate ester.

[0008] (5) After adding the phosphate ester, continue to add hydrogen peroxide until the pH reaches 1-2, then stop adding hydrogen peroxide and the oxidation reaction reaches the end point.

[0009] (6) After determining that the oxidation reaction has reached the endpoint, continue stirring for a period of time, and then filter the product and wash it with water until it is neutral to obtain the TMTD semi-finished product.

[0010] (7) Add the TMTD semi-finished product into the second reactor, add deionized water and a defoaming agent, and stir and mix thoroughly at room temperature to obtain a material.

[0011] (8) Filtering and drying the material to obtain a dry product of rubber accelerator TMTD.

[0012] Preferably, the molar ratio of dimethylamine: carbon disulfide: liquid alkali (solute of the liquid alkali solution) is 1:(1-2):(1.0-1.1).

[0013] Preferably, the mass concentration of the liquid alkali solution in step (2) is 30-35%; the mass of the added phosphate in step (4) accounts for 0.4-0.6% of the dry mass of the accelerator TMTD in step (8); deionized water is added to the commercially available phosphate, which is then heated by steam to melt before use.

[0014] Preferably, the defoaming agent in step (7) is polymethylsiloxane.

[0015] Preferably, the reaction temperature in step (1) and step (3) is 45-70°C.

[0016] Preferably, the stirring reaction time in step (6) is 9-11 minutes.

[0017] Preferably, the stirring and mixing time in step (7) is at least 30 minutes; and the drying temperature in step (8) is 75-85°C.

[0018] Preferably, the mass fraction of the hydrogen peroxide solution is 15%. During the production process, 30% mass fraction of hydrogen peroxide is added to the static mixer and then diluted with deionized water before use.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are: 1. The rubber accelerator TMTD synthesized by the method proposed in the present invention has the appearance of white crystals, large bulk density, stable product quality and good storage resistance.

[0020] 2. The method proposed by the present invention uses phosphate esters and defoamers commonly used in chemical production as additives, and the raw material cost is low and cheap and easy to obtain.

[0021] (3) Phosphate ester is added under acidic conditions during the reaction process, which better plays the role of agglomerating the target product particles; defoamer is added under neutral conditions, which further reduces the space between the target product particles and improves the packing density of the target product. Moreover, the amount of phosphate ester and defoamer added is very small, and almost no new harmful substances are generated in the wastewater, which is in line with the production concept of green production and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a photo of the internal mixing product of TT80 produced using TMTD prepared in Example 1.

[0023] Figure 2 This is a photo of the granulated product of TT80 produced by TMTD prepared in Example 1.

[0024] Figure 3 This is a photo of the internal mixing product of TT80 produced using TMTD prepared in Comparative Example 1.

[0025] Figure 4 This is a photo of the granulated product of TT80 produced by TMTD prepared in Comparative Example 1. DETAILED DESCRIPTION

[0026] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0028] Unless otherwise specified, the concentrations of the substances in the following examples are in mass percentage. Example 1 This embodiment provides a method for increasing the bulk density of the rubber accelerator TMTD, comprising the following steps.

[0029] (1) Weigh 112.5g of 40% dimethylamine solution and 102.9g of 98% pure carbon disulfide into conical flasks respectively, and use a peristaltic pump to drop the above two substances into the static mixer respectively. The dropping time is controlled within 5 minutes. After the dropping is completed, the substances in the static mixer enter the first reactor equipped with stirring, thermometer and pH online detector through overflow.

[0030] (2) Seal the first reactor, turn on the heating switch, heat the materials in the first reactor to 45°C, weigh 128.75 g of a 32% mass fraction of liquid alkali (sodium hydroxide) solution, put it into a conical flask, and use a peristaltic pump to drop the liquid alkali solution into the first reactor. The drop rate is controlled at 30 g / min. From the beginning of this step until the reaction in the first reactor is completed, maintain the stirring rate at 200 rpm. When the pH online detector shows pH = 8, stop dropping the liquid alkali solution.

[0031] (3) Weigh 119.0 g of 30% hydrogen peroxide solution and 119.0 g of deionized water, place them in different conical flasks, and use a peristaltic pump to drop the two substances into the second static mixer at a rate of 30 g / min. After the dropwise addition is completed, a 15% hydrogen peroxide solution is obtained, and then the substances in the second static mixer are controlled by a peristaltic pump at a drop rate of 20 g / min to enter the first reactor to start the oxidation reaction.

[0032] (4) Add 0.5 g of deionized water to 1.2 g of phosphate ester and heat with 100°C steam until the phosphate ester melts for later use. When the pH online detector detects the material in the first reactor and shows pH = 6, immediately add the melted water-containing phosphate ester to the first reactor.

[0033] (5) The peristaltic pump controls the 15% hydrogen peroxide solution to continue to be added at a drop rate of 20 g / min. When the pH online detector shows pH = 1, the addition is stopped.

[0034] (6) The material was stirred in the first reactor for 10 minutes and then stopped. The temperature in the first reactor was controlled not to exceed 70°C during the entire reaction process by condensing water or other means. The solid product in the obtained material was filtered and dehydrated, and washed with water until the pH value was 7. Then the material was transferred to the second reactor with stirring, and 691.2g of deionized water and 4g of defoaming agent polymethylsiloxane (Jinan Guichi Industrial Co., Ltd., viscosity 5000 at room temperature) were added at room temperature. After stirring at 200rpm for 30min, it was filtered and dehydrated, and dried at 80°C for 3h to obtain the target product TMTD.

[0035] After testing, the mass of the rubber accelerator TMTD product prepared in this example is 230.4 g, the bulk density is 42.68 g / 100 ml, the initial melting point is 142.2° C., and the purity is 99.32%.

[0036] The TMTD obtained in this example was subjected to an aging test for 48 hours at a temperature of 55°C and a humidity of 65%. The purity of the samples before and after the test was 99.32% and 99.31%, respectively. It can be concluded from the experimental data that the accelerator TMTD prepared in this example is not easily degraded, which ensures its quality during the storage period.

[0037] The rubber accelerator TMTD prepared in this example was used to prepare the pre-dispersion TT80 in the following steps: 2000g TMTD, 20g sodium stearate, 80g paraffin, 250g EPDM, and 150g naphthenic oil were placed in a pre-dispersion mixer in sequence, and the motor speed was adjusted to 80 rpm for compression mixing. When the material temperature naturally rose to 55 degrees Celsius, the mixing was stopped, the material was dumped out, and the material was placed in a granulator for granulation. According to monitoring, the sample was clumped during the mixing process, as shown in FIG. Figure 1 As shown in the figure, the cut surface of the TT80 pellets obtained in the granulation process is smooth. Figure 2 shown.

[0038] Example 2 The present embodiment is consistent with the embodiment 1 except for the special explanation.

[0039] (1) Weigh 120.8g of 40% dimethylamine solution and 110g of 98% pure carbon disulfide into conical flasks respectively, and use a peristaltic pump to drop the above two substances into the first static mixer respectively, and the dropping time is controlled within 5 minutes. After the dropwise addition is completed, the substances in the first static mixer enter the first reactor equipped with stirring, thermometer and pH online detector through overflow.

[0040] (2) Seal the first reactor, turn on the heating switch, heat the materials in the first reactor to 45°C, weigh 135g of a 30% mass fraction liquid alkali (sodium hydroxide, slightly excessive) solution, put it into a conical flask, and use a peristaltic pump to drop the liquid alkali solution into the first reactor. The drop rate is controlled at 30g / min. From the beginning of this step until the reaction in the first reactor is completed, maintain the stirring rate at 200rpm. When the pH online detector shows pH = 8.1, stop dropping the liquid alkali solution.

[0041] (3) Weigh 119.0 g of 30% hydrogen peroxide solution and 119.0 g of deionized water, place them in different conical flasks, and use a peristaltic pump to drop the two substances into the second static mixer at a rate of 30 g / min. After the dropwise addition is completed, a 15% hydrogen peroxide solution is obtained, and then the substances in the second static mixer are controlled by a peristaltic pump at a drop rate of 20 g / min to enter the first reactor to start the oxidation reaction.

[0042] (4) Add 0.5 g of deionized water to 1.2 g of phosphate ester and heat with 100°C steam until the phosphate ester melts for later use. When the pH online detector detects the material in the first reactor and shows pH = 6, immediately add the melted phosphate ester to the first reactor.

[0043] (5) The peristaltic pump controls the 15% hydrogen peroxide solution to continue to be added at a drop rate of 20 g / min. When the pH online detector shows pH = 1, the addition is stopped.

[0044] (6) The material was stirred in the first reactor for 10 minutes and then stopped. The temperature of the first reactor was controlled by the condensed water cooling system of the first reactor to be less than 65°C during the entire reaction process. The solid product in the obtained material was filtered and dehydrated, and washed with water to pH = 7. Then the material was transferred to the second reactor with stirring, 690.9g of deionized water and 4g of polymethylsiloxane were added at room temperature, stirred at 200rpm for 30min, filtered and dehydrated, and dried at 80°C for 3h to obtain the target product TMTD.

[0045] After testing, the mass of the rubber accelerator TMTD product prepared in this example is 231.1 g, the bulk density is 42.54 g / 100 ml, the initial melting point is 142.3° C., and the purity is 99.35%.

[0046] Example 3 The present embodiment is consistent with the embodiment 1 except for the special explanation.

[0047] (1) Weigh 112.5g of 40% dimethylamine solution and 102.9g of 98% pure carbon disulfide into conical flasks respectively, and use a peristaltic pump to drop the above two substances into the first static mixer respectively, and the dropping time is controlled within 5 minutes. After the dropwise addition is completed, the substances in the first static mixer enter the first reactor equipped with stirring, thermometer and pH online detector through overflow.

[0048] (2) Seal the first reactor, turn on the heating switch, heat the materials in the first reactor to 50°C, weigh 128.75g of a 35% mass fraction liquid alkali (sodium hydroxide) solution, put it into a conical flask, and use a peristaltic pump to drop the liquid alkali solution into the first reactor. The dropping rate is controlled at 30g / min. From the beginning of this step until the reaction in the first reactor is completed, maintain the stirring rate at 200rpm. When the pH online detector shows pH = 7.9, stop dropping the liquid alkali solution.

[0049] (3) Weigh 119.0 g of 30% hydrogen peroxide solution and 119.0 g of deionized water, place them in different conical flasks, and use a peristaltic pump to drop the two substances into the second static mixer at a rate of 30 g / min. After the dropwise addition is completed, a 15% hydrogen peroxide solution is obtained, and then the substances in the second static mixer are controlled by a peristaltic pump at a drop rate of 20 g / min to enter the first reactor to start the oxidation reaction.

[0050] (4) Add 0.5 g of deionized water to 1.2 g of phosphate ester and heat with 100°C steam until the phosphate ester melts for later use. When the pH online detector detects the material in the first reactor and shows pH = 6, immediately add the melted phosphate ester to the first reactor.

[0051] (5) The peristaltic pump controls the 15% hydrogen peroxide solution to continue to be added at a drop rate of 20 g / min. When the pH online detector shows pH = 1, the addition is stopped.

[0052] (6) The material was stirred in the first reactor for 11 minutes and then stopped. The temperature of the first reactor was controlled not to exceed 55°C during the entire reaction process by the condensation water cooling system of the first reactor. The solid product in the obtained material was filtered and dehydrated, and washed with water to pH = 7. Then the material was transferred to the second reactor with stirring, 691.2g of deionized water and 4g of defoaming agent polymethylsiloxane were added at room temperature, and after stirring at 200rpm for 30min, it was filtered and dehydrated, and dried at 75°C for 3h to obtain the target product TMTD.

[0053] After testing, the mass of the rubber accelerator TMTD product prepared in this example is 230.3 g, the bulk density is 42.59 g / 100 ml, the initial melting point is 141.9° C., and the purity is 99.29%.

[0054] Comparative Example 1 The difference between this comparative example and Example 1 is that no phosphate ester and defoamer are added, that is, in steps (3)-(5), a hydrogen peroxide solution is directly added dropwise until the system pH is 1; and the material in step (6) is stirred in the first reactor for 10 minutes before stopping stirring, and then directly filtered, dehydrated, washed, and dried to obtain a finished product. After testing, the obtained rubber accelerator TMTD product has a bulk density of 28.78g / 100ml, an initial melting point of 140.2℃, and a purity of 98.08%.

[0055] It can be seen from this comparative example that the accelerator TMTD produced without adding phosphate ester and defoamer has lower indicators than Example 1.

[0056] The sample was subjected to a 48-hour aging test at a temperature of 55°C and a humidity of 65%. The purity of the sample before and after the test was 98.08% and 96.27%, respectively. From the experimental data, it can be concluded that the accelerator TMTD obtained in the comparative example was significantly degraded under the experimental conditions. The rubber accelerator TMTD prepared in this comparative example was used to prepare the pre-dispersion TT80. During the mixing process, the sample was dispersed and could not form a mass. Figure 3 As shown; the TT80 pellets obtained in the granulation process have a rough cut surface, such as Figure 4 shown.

[0057] Comparative Example 2 The difference between this comparative example and Example 1 is that no defoaming agent is added, that is, the material in step (6) is stirred in the first reactor for 10 minutes before the stirring is stopped, and then directly filtered, dehydrated, washed and dried to obtain the finished product. After testing, the bulk density of the rubber accelerator TMTD product prepared in this comparative example is 29.10g / 100ml, the initial melting point is 140.2℃, and the purity is 98.0%.

[0058] It can be seen from this comparative example that the accelerator TMTD produced under the condition of adding only phosphate ester and no defoaming agent has various indicators similar to those of comparative example 1, which are all lower than those of example 1.

[0059] Comparative Example 3 The difference between this comparative example and Example 1 is that no phosphate is added, that is, in steps (3) to (5), a hydrogen peroxide solution is directly added dropwise until the pH of the system is 1; after testing, the bulk density of the rubber accelerator TMTD product is 28.41 g / 100 ml, the initial melting point is 140.3° C., and the purity is 98.3%.

[0060] It can be seen from this comparative example that the accelerator TMTD produced under the condition of adding only defoaming agent and no phosphate ester has various indicators similar to those of comparative example 1, which are all lower than those of example 1.

[0061] Comparative Example 4 The difference between this comparative example and Example 1 is that the solid product in the material obtained in step (6) is dehydrated and then washed with water to pH=6, and then the material is transferred to a second reactor with stirring, and 691.2g of deionized water and 4g of a defoamer with a mass fraction of 30% are added at room temperature. The other conditions are consistent with Example 1. After testing, the bulk density of the rubber accelerator TMTD product is 30.22g / 100ml, the initial melting point is 139.6°C, and the purity is 97.8%.

[0062] It can be seen from this comparative example that when both the defoamer and the phosphate are added, the pH condition when the defoamer is added is less than 7, that is, when the material environment is acidic, the produced accelerator TMTD has various indicators lower than those in Example 1, and the initial melting point of the product is unqualified.

[0063] After testing, the pre-dispersion TT80 prepared using the rubber accelerator TMTD prepared in Comparative Examples 2-4 also showed that the product was not dispersed into agglomerates during the mixing process, and the cut surface of the TT80 particles obtained in the granulation process was rough.

[0064] In summary, the phosphate ester and defoaming agent in the present invention are very important for the entire production process, and both are indispensable. The timing of addition is also very important. Only under appropriate conditions can the technical purpose of increasing the bulk density of the target product and improving the product quality and purity be achieved.

[0065] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a rubber accelerator TMTD with increased bulk density, characterized in that: The steps include: (1) Add dimethylamine solution and carbon disulfide to a static mixer in sequence, mix them thoroughly and then add them to a first reactor for reaction; (2) under stirring, adding a liquid alkali solution dropwise to the first reactor until the pH reaches 7.9-8.1, and then stopping the addition to obtain a sodium dimethyl disulfide formate solution; (3) under stirring, adding a hydrogen peroxide solution to the sodium dimethyl disulfide formate solution to react; (4) When the pH value is 5.9-6.1, add phosphate; (5) Continue to add the hydrogen peroxide solution until the pH reaches 1-2, then stop adding the hydrogen peroxide solution; (6) Continue stirring to react. After the reaction is completed, filter the product and wash it with water until it is neutral to obtain a TMTD semi-finished product; (7) Add the TMTD semi-finished product into the second reactor, add deionized water and a defoaming agent, and stir and mix thoroughly to obtain a material; (8) Filtering and drying the material to obtain a dry product of rubber accelerator TMTD.

2. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The molar ratio of dimethylamine: carbon disulfide: liquid alkali is 1: (1-2): (1.0-1.1).

3. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The mass concentration of the liquid alkali solution in step (2) is 30-35%; the mass of the added phosphate in step (4) accounts for 0.4-0.6% of the dry mass of the accelerator TMTD in step (8).

4. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The defoaming agent in step (7) is polymethylsiloxane.

5. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The reaction temperature in step (1) and step (3) is 45-70°C.

6. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The stirring reaction time in step (6) is 9-11 minutes.

7. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The stirring and mixing time in step (7) is at least 30 minutes; and the drying temperature in step (8) is 75-85°C.

8. The method for preparing the rubber accelerator TMTD with increased bulk density according to claim 1, characterized in that: The mass fraction of the hydrogen peroxide solution in steps (3) to (5) is 15%.

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