CN108570021B - Vulcanization accelerator CBS and continuous production method thereof - Google Patents
Vulcanization accelerator CBS and continuous production method thereof Download PDFInfo
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
- C07D277/62—Benzothiazoles
- C07D277/68—Benzothiazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
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Abstract
The invention provides a vulcanization accelerator CBS and a continuous production method thereof, wherein the method comprises the following steps: introducing a salt solution of an accelerator MBT, an acid solution of cyclohexylamine, a solvent and an oxidant into a reactor for oxidation reaction, and treating the reacted materials to obtain a CBS product; wherein the reactor is any one of a tubular reactor, a microchannel reactor or a tower reactor or the combination of at least two of the tubular reactor, the microchannel reactor and the tower reactor. According to the invention, the salt solution of 2-Mercaptobenzothiazole (MBT), the acid solution of cyclohexylamine, an oxidant and a suitable solvent are used as raw materials, the vulcanization accelerator CBS is prepared in a continuous reactor, the reaction yield can be greatly improved, and after the cyclohexylamine is recovered from the wastewater obtained by reaction through normal pressure distillation, the COD (chemical oxygen demand) in the residual water can be reduced to below 2000ppm, so that the subsequent treatment is facilitated.
Description
Technical Field
The invention belongs to the field of rubber additives, and relates to a vulcanization accelerator CBS and a continuous production method thereof.
Background
In the course of producing various rubber products of tyre, rubber tube and rubber shoe, it must use five kinds of assistants, which are rubber vulcanization accelerator, rubber anti-ageing agent, rubber vulcanization and vulcanization activator, processing type rubber assistant and special functional assistant. Among them, a rubber vulcanization accelerator, an accelerator for short, is a substance capable of accelerating vulcanization. Can shorten the vulcanizing time, reduce the vulcanizing temperature, reduce the consumption of vulcanizing agents, improve the physical and mechanical properties of rubber and the like.
The rubber vulcanization accelerator CBS (chemical name is N-cyclohexyl-2-benzothiazole sulfenamide, also known as CZ) is one of important varieties of sulfenamide accelerators, is a slow-acting vulcanization accelerator commonly used at home and abroad, has excellent scorch resistance, safe processing and short vulcanization time, can improve the stretching strength and tensile strength of vulcanized rubber, is suitable for various rubbers, has slight color change and does not frost. The rubber vulcanization accelerator is mainly used for manufacturing industrial rubber products such as tires, rubber tubes, rubber shoes, electric wires and the like.
At present, the rubber vulcanization accelerator CBS is produced by an industrialization method of oxidizing an accelerator MBT and cyclohexylamine to produce the accelerator CBS by using sodium hypochlorite or hydrogen peroxide as an oxidant. Wherein, the sodium hypochlorite oxidation method has the advantages of mature process, mild reaction condition, better product quality and higher yield (generally about 90 to 92 percent). However, the amount of wastewater produced is large, about 8 tons of wastewater are produced from 1 ton of products, and the salt content and COD in the wastewater are both high (generally over 30000 ppm), so the wastewater is difficult to carry out biochemical treatment (has biotoxicity) and is not favorable for environmental protection. The hydrogen peroxide method can avoid the problem of high salt content in the wastewater, but the hydrogen peroxide has strong activity, more side reactions are generated in the oxidation process compared with the sodium hypochlorite oxidation method, and the product yield is also reduced compared with the sodium hypochlorite oxidation method.
The oxygen catalytic oxidation method is favorable for environmental protection due to the great reduction of the wastewater yield, and is researched by universities and enterprises in recent years. However, the oxygen oxidation process has the problems of low conversion rate, slow reaction speed, high process risk, large equipment investment and the like, and the feasibility of further industrial conversion is influenced.
In addition, the current mainstream CBS industrial production process mainly adopts kettle type batch reaction, and certain fluctuation exists between batches no matter from the control of process parameters such as the feeding amount, the temperature in the reaction process, the feeding speed and the like, so that the yield and the quality of products between batches are obviously influenced, and the stability of industrial production is further reduced. Moreover, because the raw material MBT in the current market is mainly refined by a new solvent method, the purity of the raw material MBT is slightly lower than that of the MBT refined by the traditional acid-base method, but the composition of components of the MBT is greatly changed along with different MBT batches, the difficulty of the batch production process of the stabilizing accelerator CBS is further increased, the reaction evaluation yield is further reduced, the COD (chemical oxygen demand) of the wastewater is further increased, and the product quality fluctuation is more obvious. The treatment mode of the production wastewater is also a difficult problem which troubles CBS manufacturers.
Patent CN106800540a discloses a method for preparing rubber vulcanization accelerator CBS by using a microchannel reactor, which adopts excessive cyclohexylamine to dissolve raw material MBT as reaction raw material, and adopts hydrogen peroxide, sodium hypochlorite or oxygen to synthesize accelerator CBS in the microchannel reactor under the action of a catalyst. Although the method provides another method for continuously preparing the rubber vulcanization accelerator CBS, the reaction residence time in the microchannel reactor is too long, and the maximum flux of a single reactor is only 15L/h, so that the technology has no industrialization capability at all, the reaction yield is low (only between 87% and 95%), and the purity of the reaction product cannot be ensured.
Disclosure of Invention
Aiming at the problems in the production process of the conventional rubber vulcanization accelerator CBS, the invention provides a vulcanization accelerator CBS and a continuous production method thereof. According to the invention, the salt solution of 2-Mercaptobenzothiazole (MBT), the acid solution of cyclohexylamine, an oxidant and a proper solvent are used as raw materials, the vulcanization accelerator CBS is prepared in a continuous reactor, the reaction yield can be greatly improved, and after the cyclohexylamine is recovered from the wastewater obtained by the reaction through normal pressure distillation, the COD in the residual water can be reduced to below 2000, so that the subsequent treatment is facilitated.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a continuous process for the production of a vulcanization accelerator CBS, said process comprising the steps of:
introducing a salt solution of an accelerator MBT, an acid solution of cyclohexylamine, a solvent and an oxidant into a reactor for oxidation reaction, and treating the reacted materials to obtain a CBS product;
wherein the reactor is any one of a tubular reactor, a microchannel reactor or a tower reactor or the combination of at least two of the tubular reactor, the microchannel reactor and the tower reactor.
In the invention, the accelerator MBT is 2-mercaptobenzothiazole for short.
In the invention, the salt solution of MBT and the acid solution of cyclohexylamine are used as raw materials, a proper solvent and an appropriate oxidant are selected, and the oxidation synthesis reaction is carried out in a continuous reactor under the condition of not using a catalyst, so that the reaction residence time in the reactor is greatly shortened, and the optimal residence time is only 0.5-10 s. The maximum flux of the single equipment can reach 1.8m on the equipment with the same volume 3 The production capacity can be expanded to 1200 times to the maximum extent, and the method has more industrial value.
In the present invention, for the conventional M-Na salt process (generally common in DCBS production, such as the method involved in CN 102838564 a) for preparing a vulcanization accelerator, a solution of MBT (hereinafter, M-Na salt is taken as an example) and an acid solution of cyclohexylamine (hereinafter, cyclohexylamine hydrochloride solution is taken as an example) are prepared respectively by changing the way that inorganic acids (sulfuric acid, hydrochloric acid, etc.) need to be synchronously dripped with a sodium hypochlorite solution and an M-Na salt solution, and the following objectives are mainly achieved:
on one hand, a hydrochloric acid solution of cyclohexylamine and a hydrochloric acid solution of MBT are prepared respectively, so that hydrochloric acid is mixed with cyclohexylamine firstly, the effect of neutralizing cyclohexylamine can be achieved, and the risk of ester solvent hydrolysis is reduced; and different from kettle type or bottle type dropping reaction, in a continuous flow reactor such as a tubular reactor, a microchannel reactor or a tower type reactor, if hydrochloric acid, M-Na salt and cyclohexylamine are directly mixed, besides the reaction of the hydrochloric acid and the cyclohexylamine to generate cyclohexylamine hydrochloride, the reaction of the M-Na salt and the hydrochloric acid to generate sodium chloride and MBT can also occur, and the MBT contacts with an oxidant, side reaction can occur to generate 2, 2' -dithiodibenzothiazole (abbreviated as MBTS) or other resin type by-products, so that the yield is reduced, and the risk of pipeline blockage is increased. Therefore, an M-Na salt solution and a cyclohexylamine hydrochloric acid solution are required to be prepared respectively, and then the subsequent reaction is carried out;
on the other hand, the preparation of the M-Na salt solution and the hydrochloric acid solution of the cyclohexylamine respectively simplifies the feeding mode, and the original five raw materials of the cyclohexylamine, the hydrochloric acid, the solvent, the M-Na salt solution and the oxidant are respectively fed, so that four kinds of feeding are changed, the control point number in continuous production is reduced, and the process stability is improved.
The following technical solutions are preferred but not limited to the technical solutions provided by the present invention, and the technical objects and advantages of the present invention can be better achieved and realized by the following technical solutions.
As a preferred embodiment of the present invention, the preparation method of the salt solution of the accelerator MBT comprises the following steps: mixing accelerator MBT with alkali solution under stirring to obtain salt solution of MBT.
Preferably, the alkali solution comprises NaOH solution, KOH solution or NH 3 ·H 2 O solution or a mixture of at least two of them, typical but non-limiting examples of such combinations are: combination of NaOH solution and KOH solution, KOH solution and NH 3 ·H 2 Combinations of O solutions, etc., preferably NaOH solutions. The MBT salt solution prepared by the NaOH solution is an M-Na salt solution.
In a preferred embodiment of the present invention, the concentration of the alkali solution is 1 wt% to 50 wt%, for example, 3 wt%, 5wt%, 10 wt%, 15 wt%, 25 wt%, or 40 wt%, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
Preferably, the mass ratio of the accelerator MBT to the alkaline solution is 1 (0.3 to 4.0), for example, 1:0.5, 1:1.1, 1:1.5, 1:2.0, 1:2.5, 1:2.8, or 1:3.0, but not limited to the recited values, and other values not recited within this range are also applicable, preferably 1 (0.5 to 1.5).
Preferably, the mixing time of the accelerator MBT with the alkaline solution under stirring is 0 to 4 hours, such as 0.5 hour, 1 hour, 1.5 hour, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, but not limited to the recited values, and other non-recited values within this range are equally applicable, preferably 0 to 2 hours.
Preferably, the mixing temperature of the accelerator MBT with the alkaline solution under stirring is 0 to 100 ℃, for example 5 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, but not limited to the recited values, and other values not recited within this range are equally applicable, preferably 40 to 60 ℃.
As a preferable technical scheme of the invention, the preparation method of the cyclohexylamine acid solution comprises the following steps: and mixing the cyclohexylamine and the acid under the stirring condition, and diluting to obtain an acid solution of the cyclohexylamine.
Preferably, the acid comprises any one of hydrochloric acid, sulphuric acid, nitric acid or phosphoric acid, or a mixture of at least two of these, typical but non-limiting examples of such combinations being: a combination of hydrochloric acid and sulfuric acid, a combination of nitric acid and phosphoric acid, a combination of sulfuric acid, nitric acid and phosphoric acid, and the like.
In a preferred embodiment of the present invention, the acid concentration is 1 wt% to 98 wt%, for example, 1 wt%, 11 wt%, 21 wt%, 51 wt%, or 71 wt%, but the acid concentration is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
Preferably, the molar ratio of cyclohexylamine to solute in the acid solution is 1 (0.1-2), for example 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 2, but not limited to the recited values, and other values not recited within this range are equally applicable, preferably 1 (0.3-1).
Preferably, the solvent used in the dilution is water.
Preferably, the mass ratio of the solution of cyclohexylamine in acid to the solvent used in dilution is 1 (0 to 2), for example 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 2, but not limited to the values listed, and other values not listed in this range are equally applicable, preferably 1 (0.5 to 1).
Preferably, the temperature at which the cyclohexylamine and the acid are mixed under stirring is 0 to 100 ℃, for example, 5 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, but not limited to the recited values, and other values not recited within the range of the recited values are also applicable, preferably 40 to 45 ℃.
As a preferred embodiment of the present invention, the solvent is any one of methyl formate, methyl acetate, ethyl formate, ethyl acetate, triglycerol acetate, chloroform, carbon tetrachloride, benzene, toluene, ethylbenzene, cumene or cyclohexane or a combination of at least two thereof, and the combination is exemplified by, typically but not limited to: a combination of methyl formate and methyl acetate, a combination of ethyl formate and ethyl acetate, a combination of triglycerol acetate and chloroform, a combination of carbon tetrachloride and benzene, a combination of toluene and ethylbenzene, a combination of methyl formate, methyl acetate, ethyl formate and ethyl acetate, a combination of ethyl acetate, triglycerol acetate and chloroform, a combination of benzene, toluene, ethylbenzene, cumene and cyclohexane, and the like, preferably ethyl acetate and/or toluene.
In the present invention, the best effect is achieved by using ethyl acetate and/or toluene as the solvent.
In the present invention, the solvent used is substantially different from the solvent (such as isopropanol) used in the conventional salt solution process for preparing MBT of vulcanization accelerator (generally common in DCBS production, such as the process referred to in CN 102838564 a).
For example, the reaction involved in CN 102838564a is a solid-liquid heterogeneous reaction, and the reaction process is that an intermediate product formed by a raw material M-Na salt and dicyclohexylamine (mainly a complex salt formed by complexing MBT and dicyclohexylamine) and an oxidant (sodium hypochlorite) undergo a redox reaction to generate a target product DCBS. The final product DCBS can be suspended in a reaction system in a solid form, and the introduction of the isopropanol which is a water-soluble solvent is mainly aimed at increasing the solubility of a reaction intermediate product in a water phase, so that the oxidation-reduction reaction of part of the intermediate product and an oxidant is changed from a solid-liquid heterogeneous reaction into a homogeneous reaction in water, further the reaction speed and the reaction yield are improved, and the side reaction caused by deep oxidation in the process of contacting the oxidant with the solid-phase intermediate product for a long time is reduced. However, the introduced isopropanol solvent can only locally increase the reaction speed, and cannot essentially solve the problem of the solid-liquid heterogeneous reaction process in the DCBS preparation. Therefore, most of the industrialized cases find that the conversion rate of the raw material MBT is about 90 percent basically or even lower after the technology is industrialized. Also, since the final product DCBS is suspended in the reaction system in a solid form, it cannot achieve continuous production in a continuous reactor.
In the synthesis process of the vulcanization accelerator CBS, the cyclohexylamine aqueous solution not only functions as a raw material, but also functions as a solvent, so that an intermediate product (salt formed by complexing MBT and cyclohexylamine) and a final product CBS formed in the reaction process can be dissolved in the reaction system, and the occurrence of a heterogeneous reaction is avoided, so that the reaction can be carried out in a tubular reactor or even a microchannel reactor without blocking a pipeline, as described in the technology of patent CN106800540 a.
However, cyclohexylamine is more basic than dicyclohexylamine, and the bridge-type cyclic structure of cyclohexylamine makes the salt formed by the complexation of cyclohexylamine and MBT more susceptible to oxidation and even deep oxidation, which in turn reduces the yield of CBS product. In contrast, the possibility of deep oxidation is further amplified by using the aqueous solution of cyclohexylamine as a solvent and making the intermediate product and the oxidizing agent in the aqueous phase. And CBS generated by the reaction can be dissolved in the aqueous solution of cyclohexylamine, is in a homogeneous phase state with an oxidant for a long time, and can be deeply oxidized and converted into a byproduct, so that the reaction yield is further reduced. This phenomenon is readily seen in the example of CN106800540A, and the yield is substantially maintained below 90%. Meanwhile, this phenomenon is also reflected in the synthesis of the promoter TBBS, but since tert-butylamine does not have the special bridged cyclic structure of cyclohexylamine, the salt formed by complexing with MBT has lower reducibility than cyclohexylamine, so the yield of TBBS synthesized in this way is higher than CBS, but still cannot approach 100% of theoretical conversion, which is not difficult to see in the example of CN 106866578A.
Thus, the present invention introduces a solvent, i.e., any one of methyl formate, methyl acetate, ethyl formate, ethyl acetate, triglycerol acetate, chloroform, carbon tetrachloride, benzene, toluene, ethylbenzene, cumene or cyclohexane or a combination of at least two thereof, in view of the above problems. The aim is not only to replace cyclohexylamine as a solvent, but also to enable the cyclohexylamine and an intermediate product (salt formed by complexing MBT and cyclohexylamine) to migrate from a water phase to a solvent phase, and further enable the oxidation process to be changed from a single water phase to a liquid-liquid two-phase reaction between a water phase and an oil phase. Compared with homogeneous reactions in CN 102838564A, CN 106866578A and CN106800540A, the introduced oil/water liquid-liquid two-phase reaction mainly occurs on a phase interface, the oxidation process becomes milder and more controllable, and the occurrence of side reactions can be greatly reduced.
Meanwhile, the generated target product CBS can be well dissolved in the solvent, and excessive contact with the oxidant is avoided, so that secondary oxidation of the generated product is reduced, and the product yield is further improved. Therefore, the target product of the reaction process can reach more than 99.6 percent at most, and the occurrence of side reactions which are basically completely avoided can be considered.
However, oil/water liquid two-phase reaction requires better mixing of the two phases to increase the reaction rate without changing the reaction yield. In contrast, the invention adopts a continuous reactor (such as a microchannel reactor and the like), the material mixing intensity in the reactor is higher, and the mass transfer efficiency is higher. Therefore, the reaction process related by the invention has the reaction residence time of only 0.5-10s, which is obviously lower than all the reaction technologies reported at present.
The invention is also superior to other prior art, and the oil/water liquid two-phase reactant is mixed in the continuous reactor (such as micro-channel reactor) without considering the problem of side reaction in the process of intensified mixing. Therefore, the reaction time can be greatly reduced under the condition of keeping the product yield, so that the method has higher industrial value. Although the microchannel reactor is used in the existing method for preparing the vulcanization accelerator CBS, the yield of homogeneous reaction is uncontrollable, and the shortening of the reaction time can cause deep oxidation to reduce the yield of target products, so that the characteristic of high mass and heat transfer efficiency of the microchannel reactor cannot be exerted. And longer reaction residence time represents lower reaction efficiency, so that the industrial value is greatly reduced.
Preferably, the oxidant is any one or a combination of at least two of oxygen, hydrogen peroxide, sodium hypochlorite solution, dimethyl sulfoxide, chlorine, potassium permanganate solution or potassium chlorate solution, and the combination is typically but not limited to: a combination of oxygen and hydrogen peroxide, a combination of oxygen and a sodium hypochlorite solution, a combination of oxygen and chlorine, a combination of a sodium hypochlorite solution and a potassium chlorate solution, a combination of chlorine and a sodium hypochlorite solution and the like, and preferably a sodium hypochlorite solution.
Preferably, the sodium hypochlorite solution has an available chlorine content of 8 wt% to 17 wt%, such as 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, or 17 wt%, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the feeding mass ratio of the salt solution of MBT and the acid solution of cyclohexylamine is 1 (0.5-5), such as 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but not limited to the enumerated values, and other non-enumerated values within the numerical range are equally applicable, preferably 1 (1-2.5).
Preferably, the feed mass ratio of the salt solution of MBT to the solvent is 1 (1-5), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but not limited to the recited values, and other values not recited within this range are equally applicable, preferably 1 (1.5-3).
Preferably, the feed mass ratio of the salt solution of MBT and the oxidant is 1 (1-8), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, or 1:8, but not limited to the recited values, and other values within this range are equally applicable, preferably 1 (1.2-4).
Preferably, the oxidation reaction is carried out at a reaction temperature of 10 ℃ to 100 ℃, for example, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃, but not limited to the recited values, and other values not recited within this range are equally applicable, preferably 20 ℃ to 50 ℃.
Preferably, the reactor is a microchannel reactor.
Preferably, the residence time of the reaction in the reactor is between 0.5s and 2400s, for example 0.5s, 1s, 3s, 10s, 50s, 100s, 300s, 500s, 1000s, 1500s, 2000s, 2200s or 2400s, etc., but is not limited to the values listed, and other values not listed within this range of values are equally applicable, preferably between 0.5s and 10 s.
As a preferred technical scheme of the invention, the reacted materials are processed to obtain a CBS product, which specifically comprises the following steps: and (3) recovering and filtering the reacted materials by using a solvent to obtain a CBS crude product, and washing and drying the CBS crude product to obtain the CBS product.
In a preferred embodiment of the present invention, the solvent recovery is vacuum evaporation.
Preferably, the evaporation is carried out under reduced pressure until no solvent is distilled off.
Preferably, the solvent recovery temperature is 20 ℃ to 80 ℃, such as 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃, but not limited to the cited values, and other values not listed in the numerical range are equally applicable, preferably 40 ℃ to 80 ℃.
Preferably, the degree of vacuum in the solvent recovery is controlled to 10kPa to 80kPa, for example, 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, or the like, but the degree is not limited to the recited values, and other values not recited in the range of the values are also applicable, and 10kPa to 50kPa is preferable.
Preferably, the washing of the CBS crude product comprises organic solvent washing and water washing in sequence;
preferably, the organic solvent used in the organic solvent washing includes an aqueous solution of any one or at least two of methanol, ethanol, isopropanol, methyl formate, methyl acetate, ethyl formate, ethyl acetate, triglycerol acetate, acetone, tert-butylamine, cyclohexylamine, or aniline, and typical but non-limiting examples of the combination are: an aqueous solution of methanol and ethanol, an aqueous solution of methyl formate and methyl acetate, an aqueous solution of ethyl formate and ethyl acetate, a combination of ethyl formate, ethyl acetate and triglycerol acetate, a combination of acetone, tert-butylamine, cyclohexylamine and aniline, and the like, preferably an aqueous solution of cyclohexylamine.
As a preferred technical scheme of the invention, the method comprises the following steps:
(a) preparing an M-Na salt solution: mixing an accelerator MBT with a NaOH solution with the concentration of 20wt% -35 wt% under the stirring condition to prepare an M-Na salt solution; wherein the mass ratio of the accelerator MBT to the NaOH solution is 1 (0.5-1.5), the mixing time is 0-2 h, and the mixing temperature is 40-60 ℃;
preparing hydrochloric acid solution of cyclohexylamine: mixing cyclohexylamine and hydrochloric acid with the concentration of 20-30 wt% under the stirring condition at the temperature of 40-45 ℃, and diluting with water to obtain a hydrochloric acid solution of cyclohexylamine; wherein the molar ratio of cyclohexylamine to solute in the acid solution is 1 (0.3-1), and the mass ratio of cyclohexylamine to water is 1 (0.5-1);
(b) introducing an M-Na salt solution, a cyclohexylamine hydrochloric acid solution, a solvent ethyl acetate and/or toluene and an oxidant sodium hypochlorite solution into a microchannel reactor to perform oxidation reaction at the temperature of between 20 and 50 ℃, wherein the reaction residence time is between 0.5 and 10 seconds; the feeding mass ratio of the M-Na salt solution to the cyclohexylamine hydrochloric acid solution is 1 (1-2.5), the feeding mass ratio of the M-Na salt solution to the solvent is 1 (1.5-3), and the feeding mass ratio of the M-Na salt solution to the oxidant is 1 (1.2-4);
(c) and (3) evaporating the material subjected to the oxidation reaction under reduced pressure at 40-80 ℃ and under the vacuum degree of 10-50 kPa to recover the solvent, filtering to obtain a CBS crude product, and washing, washing and drying the CBS crude product with cyclohexylamine aqueous solution in sequence to obtain the CBS product.
In a second aspect, the invention provides the vulcanization accelerator CBS prepared by the continuous production method.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention takes M-Na salt solution of 2-Mercaptobenzothiazole (MBT), hydrochloric acid solution of cyclohexylamine, solvent and oxidant as raw materials, prepares vulcanization accelerator CBS in a continuous reactor, the product yield can reach more than 99.6 percent (based on the content of MBT), and the product purity can reach more than 99.6 weight percent;
(2) after the waste water obtained by the reaction of the method is subjected to normal pressure distillation to recover cyclohexylamine, the COD in the residual water can be reduced to below 2000 ppm;
(3) the method has the advantages of high reaction speed, high product yield, low COD of the wastewater, easy treatment and the like, and is a new technology with higher industrial value.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
The invention provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
introducing an M-Na salt solution of an accelerator MBT, a hydrochloric acid solution of cyclohexylamine, a solvent and an oxidant into a reactor for oxidation reaction, and treating the reacted materials to obtain a CBS product;
wherein the reactor is any one of a tubular reactor, a microchannel reactor or a tower reactor or the combination of at least two of the tubular reactor, the microchannel reactor and the tower reactor.
The following are typical, but non-limiting, examples of the present invention:
example 1:
the embodiment provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
(1) preparing an M-Na salt solution: mixing 400g of accelerator MBT with 360g of NaOH solution with the concentration of 32 wt%, and stirring for 2h at 50 ℃ to prepare M-Na salt solution;
preparing hydrochloric acid solution of cyclohexylamine: mixing 316g of cyclohexylamine with 376g of industrial hydrochloric acid with the concentration of 31 wt%, adding 224g of water, and stirring at 35 ℃ to obtain a hydrochloric acid solution of cyclohexylamine;
(2) introducing an M-Na salt solution, a cyclohexylamine hydrochloric acid solution, a solvent ethyl acetate and a sodium hypochlorite solution with the available chlorine content of 17% into a microchannel reactor at the speed of 72mL/min of the M-Na salt solution, 115mL/min of the cyclohexylamine hydrochloric acid solution, 154mL/min of ethyl acetate and 96mL/min of the sodium hypochlorite solution for oxidation reaction, wherein the reaction residence time is 2s, the reaction temperature is 30 ℃, the microchannel reactor is formed by connecting 4 reactors in series, the volume of each reactor is 3.2mL, and the total volume of the reactors after series connection is 12.8 mL;
(4) collecting the material flowing out of the reactor, carrying out reduced pressure distillation at 40-50 ℃ under the vacuum degree of-0.05 MPa to recover ethyl acetate until no distillate exists, and filtering the residual solid-liquid mixture to obtain a crude product; and washing the crude product obtained by filtering with 200mL of cyclohexylamine aqueous solution once, washing with 200mL of water for 2 times to obtain a wet CBS material, and drying to obtain a CBS finished product.
The CBS yield of the example was determined to be 99.6% (based on the MBT content), the CBS purity was 99.6 wt%, the appearance was white microcrystalline powder, and the residual COD was 1900ppm after the cyclohexylamine was recovered from the waste water by atmospheric distillation.
Example 2:
the embodiment provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
(1) preparing an M-Na salt solution: mixing 2t of accelerator MBT with 2.4t of NaOH solution with the concentration of 30wt%, and stirring for 2h at 60 ℃ to prepare M-Na salt solution;
(2) preparing hydrochloric acid solution of cyclohexylamine: mixing 1.8t of cyclohexylamine, 2.2t of industrial hydrochloric acid with the concentration of 30wt% and 1.2t of water, and stirring at 40 ℃ to obtain a hydrochloric acid solution of cyclohexylamine;
(3) the M-Na salt solution is mixed,The hydrochloric acid solution of cyclohexylamine, the solvent toluene and the sodium hypochlorite solution with the effective chlorine content of 17 percent are mixed according to the M-Na salt solution of 0.74M 3 H, cyclohexylamine hydrochloride salt solution 1m 3 H, toluene 2.2m 3 H, sodium hypochlorite solution 1.07m 3 Introducing the reactant into a microchannel reactor at a speed of/h for oxidation reaction, wherein the reaction residence time is 2s, the reaction temperature is 40 ℃, the microchannel reactor is formed by connecting 10 single reactors in series, the volume of each single reactor is 270mL, and the total volume of the reactors after the series connection is 2700 mL;
(4) collecting the material flowing out of the reactor, carrying out reduced pressure distillation at the vacuum degree of-0.09 MPa and the temperature of 65-75 ℃ to recover toluene until no distillate exists, and filtering the residual solid-liquid mixture to obtain a crude product; and washing the crude product obtained by filtering with 1t of cyclohexylamine aqueous solution once, washing with 1t of water for 2 times to obtain a CBS wet material, and drying to obtain a CBS finished product.
The CBS yield is 99.6 percent (based on the content of MBT), the CBS purity is 99.7 percent by weight, the CBS is white microcrystalline powder in appearance, and the residual COD is 1830ppm after the wastewater is subjected to atmospheric distillation to recover the cyclohexylamine.
Example 3:
the embodiment provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
(1) preparing an M-K salt solution: stirring 400g of accelerator MBT and 536g of KOH solution with the concentration of 30wt% for 3 hours at 40 ℃ to prepare M-K salt solution;
(2) preparing a sulfuric acid solution of cyclohexylamine: 427g cyclohexylamine and 469g sulfuric acid with the concentration of 20wt% are stirred at 50 ℃ to obtain a sulfuric acid solution of cyclohexylamine;
(3) introducing an M-K salt solution, a cyclohexylamine sulfuric acid solution, a methyl acetate solvent and a 17% hydrogen peroxide solution into a microchannel reactor for oxidation reaction at the speed of 14mL/min of the M-K salt solution, 19mL/min of a cyclohexylamine sulfate solution, 80mL/min of methyl acetate and 21mL/min of a hydrogen peroxide solution, wherein the reaction residence time is 5s, the reaction temperature is 50 ℃, the microchannel reactor is formed by connecting 5 monomer reactors in series, the volume of each reactor is 1.86mL, and the total volume of the reactors after the series connection is 9.3 mL;
(4) collecting materials flowing out of the reactor, carrying out reduced pressure distillation at the vacuum degree of-0.01 MPa and the temperature of 20-30 ℃ to recover methyl acetate until no distillate exists, and filtering a residual solid-liquid mixture to obtain a crude product; and washing the crude product obtained by filtering with 200ml of cyclohexylamine aqueous solution once, washing with 200ml of water for 2 times to obtain a CBS wet material, and drying to obtain a CBS finished product.
The CBS yield was found to be 95.3% (based on the MBT content), the CBS purity was found to be 98.9 wt%, the CBS was found to be white microcrystalline powder in appearance, and the residual COD was 1950ppm after the cyclohexylamine was recovered from the waste water by atmospheric distillation.
Example 4:
the embodiment provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
(1) configuration of M-NH 3 Salt solution: stirring 400g of accelerator MBT and 244g of ammonia with the concentration of 25 wt% for 4h at 60 ℃ to prepare M-NH 3 A salt solution;
(2) preparing a nitric acid solution of cyclohexylamine: stirring 356g of cyclohexylamine, 452g of nitric acid with the concentration of 50 wt% and 356g of water at 45 ℃ to obtain a nitrate solution of cyclohexylamine;
(3) reacting M-NH 3 Salt solution, nitrate solution of cyclohexylamine, solvent cyclohexane and potassium chlorate solution with concentration of 3% according to M-NH 3 Feeding 10mL/min of salt solution, 17mL/min of nitrate solution of cyclohexylamine, 23mL/min of cyclohexane and 62mL/min of potassium chlorate solution into a microchannel reactor according to the feeding mass ratio for oxidation reaction, wherein the reaction residence time is 10s, the reaction temperature is 20 ℃, the microchannel reactor is formed by connecting 10 monomer reactors in series, the volume of each reactor is 1.86mL, and the total volume of the reactors after series connection is 18.6 mL;
(4) collecting the material flowing out of the reactor, carrying out reduced pressure distillation at the vacuum degree of-0.07 MPa and the temperature of 30-40 ℃ to recover cyclohexane until no distillate exists, and filtering the residual solid-liquid mixture to obtain a crude product; and washing the crude product obtained by filtering with 200ml of cyclohexylamine aqueous solution once, washing with 200ml of water for 2 times to obtain a CBS wet material, and drying to obtain a CBS finished product.
The CBS yield is 89.5% (based on the content of MBT), the CBS purity is 98.3 wt%, the CBS is white microcrystalline powder in appearance, and the residual COD is 2080ppm after the cyclohexylamine is recovered from the wastewater through atmospheric distillation.
Example 5:
the embodiment provides a continuous production method of a vulcanization accelerator CBS, which comprises the following steps:
(1) preparing an M-Na salt solution: mixing 400g of accelerator MBT with 360g of NaOH solution with the concentration of 32 wt%, and stirring for 2h at 50 ℃ to prepare M-Na salt solution;
(2) preparing hydrochloric acid solution of cyclohexylamine: mixing 316g of cyclohexylamine with 376g of industrial hydrochloric acid with the concentration of 31 wt%, adding 224g of water, and stirring at 35 ℃ to obtain a hydrochloric acid solution of cyclohexylamine;
(3) introducing an M-Na salt solution, a cyclohexylamine hydrochloric acid solution, a solvent ethyl acetate and a sodium hypochlorite solution with an effective chlorine content of 17% into a microchannel reactor at the speed of 72mL/min of the M-Na salt solution, 115mL/min of the cyclohexylamine hydrochloric acid solution, 154mL/min of ethyl acetate and 96mL/min of the sodium hypochlorite solution for oxidation reaction, wherein the reaction residence time is 10s, the reaction temperature is 45 ℃, and the volume of the tower reactor is 64 mL;
(4) collecting the material flowing out of the reactor, carrying out reduced pressure distillation at 40-50 ℃ under the vacuum degree of-0.05 MPa to recover ethyl acetate until no distillate exists, and filtering the residual solid-liquid mixture to obtain a crude product; and washing the crude product obtained by filtering with 200mL of cyclohexylamine aqueous solution once, washing with 200mL of water for 2 times to obtain a wet CBS material, and drying to obtain a CBS finished product.
The CBS yield of this example was determined to be 99.2% (based on the MBT content), the CBS purity was 99.3 wt%, the appearance was white microcrystalline powder, and the residual COD was 1980ppm after the cyclohexylamine was recovered from the waste water by atmospheric distillation.
Comparative example 1:
this comparative example provides a continuous process for the production of the vulcanization accelerator CBS, which comprises the following steps with reference to the process of example 1, with the difference that: step (1) is not provided with a hydrochloric acid solution of cyclohexylamine, and in step (2), an M-Na salt solution, cyclohexylamine, hydrochloric acid, a solvent ethyl acetate and a sodium hypochlorite solution with an effective chlorine content of 17% are respectively added into a microchannel reactor according to the dosage proportion in example 1;
in the comparative example, since hydrochloric acid solution of cyclohexylamine was not provided, equipment clogging occurred many times during the reaction, and it was determined that the CBS yield was 85.9% (based on the content of MBT), the CBS purity was 98.7 wt%, and the residual COD was 8500ppm after cyclohexylamine was recovered from the wastewater by atmospheric distillation.
Comparative example 2:
this comparative example provides a continuous production method of a vulcanization accelerator CBS, which does not provide an M-Na salt solution and a hydrochloric acid solution of cyclohexylamine, but dissolves the accelerator M in cyclohexylamine to form a solution, and feeds the solution formed by dissolving the accelerator M in cyclohexylamine and a sodium hypochlorite solution having an available chlorine content of 17% to a microchannel reactor, i.e., a reaction condition in CN 106800540A.
In this comparative example, since the acid solution of cyclohexylamine was not used, the CBS yield was only 89.1% (based on the content of MBT) and the CBS purity was 98.3 wt%, the residual COD after recovering cyclohexylamine from the waste water by atmospheric distillation was 9500 ppm.
It can be seen from the above examples and comparative examples that the vulcanization accelerator CBS is prepared in a continuous reactor by using an M-Na salt solution of 2-Mercaptobenzothiazole (MBT), a hydrochloric acid solution of cyclohexylamine, a solvent and an oxidant as raw materials, wherein the product yield can reach more than 99.6% (based on the content of MBT), and the product purity can reach more than 99.6 wt%;
after the waste water obtained by the reaction of the method is subjected to normal pressure distillation to recover cyclohexylamine, the COD in the residual water can be reduced to below 2000 ppm;
the method has the advantages of high reaction speed, high product yield, low COD of the wastewater, easy treatment and the like, and is a new technology with higher industrial value.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (1)
1. A continuous production method of a vulcanization accelerator CBS, characterized by comprising the steps of:
(a) preparing an M-Na salt solution: mixing an accelerator MBT with a NaOH solution with the concentration of 20-35 wt% under the stirring condition to prepare an M-Na salt solution; wherein the mass ratio of the accelerator MBT to the NaOH solution is 1 (0.5-1.5), the mixing time is 0-2 h, and the mixing temperature is 40-60 ℃;
preparing an acid solution of cyclohexylamine: mixing cyclohexylamine and 20-30 wt% acid at 40-45 ℃ under the stirring condition, and diluting with water to obtain an acid solution of cyclohexylamine; wherein the molar ratio of cyclohexylamine to solute in the acid solution is 1 (0.3-1), and the mass ratio of cyclohexylamine to water is 1 (0.5-1);
(b) introducing an M-Na salt solution, an acid solution of cyclohexylamine, a solvent ethyl acetate and/or toluene and an oxidant sodium hypochlorite solution into a microchannel reactor to perform an oxidation reaction at 20-50 ℃, wherein the residence time of the reaction is 0.5-10 s; the feeding mass ratio of the M-Na salt solution to the acid solution of cyclohexylamine is 1 (1-2.5), the feeding mass ratio of the M-Na salt solution to the solvent is 1 (1.5-3), and the feeding mass ratio of the M-Na salt solution to the oxidant is 1 (1.2-4); the oxidation reaction is carried out on the phase interface of oil/water liquid phases;
(c) and (3) evaporating the material subjected to the oxidation reaction under reduced pressure at 40-80 ℃ and under the vacuum degree of 10-50 kPa to recover the solvent, filtering to obtain a CBS crude product, and washing, washing and drying the CBS crude product with a cyclohexylamine aqueous solution in sequence to obtain the CBS product.
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| CN111072595B (en) * | 2020-01-19 | 2022-08-19 | 山东尚舜化工有限公司 | Method for preparing rubber accelerator DCBS |
| CN112624945B (en) * | 2020-12-30 | 2023-04-25 | 山东尚舜化工有限公司 | Method and equipment for continuously synthesizing rubber vulcanization accelerator S |
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| CN102827104A (en) * | 2012-09-25 | 2012-12-19 | 科迈化工股份有限公司 | Method for synthesizing rubber vulcanization accelerator CZ by two-step process by using sodium hypochlorite as oxidizer |
| CN106800540A (en) * | 2017-03-30 | 2017-06-06 | 山东斯递尔化工科技有限公司 | A kind of method that utilization micro passage reaction prepares rubber vulcanizing accelerator CBS |
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| CN102827104A (en) * | 2012-09-25 | 2012-12-19 | 科迈化工股份有限公司 | Method for synthesizing rubber vulcanization accelerator CZ by two-step process by using sodium hypochlorite as oxidizer |
| CN106800540A (en) * | 2017-03-30 | 2017-06-06 | 山东斯递尔化工科技有限公司 | A kind of method that utilization micro passage reaction prepares rubber vulcanizing accelerator CBS |
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