KR19980037100A - MBT recovery from solid waste of 2-mercapto benzothiazol - Google Patents

Abstract

The present invention relates to a method for recovering only MBT, which is an active ingredient, from a solid waste generated in the manufacturing process of 2-mercapto benzochiazole (MBT) by a solid-liquid extraction method.

As a method for providing a method for quantitatively recovering only high-purity MBT from solid waste, the solid waste is pulverized into particles of 50 to 200 mesh size, and then dissolved using a solvent (polar organic solvent) having selective solubility and then 50 to It is a method of concentrating in the temperature range of 100 degreeC.

The present invention can achieve breakthrough improvements in MBT yield improvement and waste disposal.

Description

MBT recovery from solid waste of 2-mercapto benzothiazol

Figure 1 is a photograph taken with an electron microscope of a single layer of solid waste before MBT extraction

Figure 2 is a photograph taken with an electron microscope of a monolayer of solid waste after extraction of MBT according to the present invention

Detailed description of the invention

[Objective of the invention]

[Technical Field to which the Invention belongs and Conventional Technology in the Field]

The present invention relates to a vulcanization accelerator represented by the following structural formula, that is, a method for recovering only MBT, which is an active ingredient, from a solid waste generated in the manufacturing process of 2-mercapto benzothiazol (hereinafter referred to as MBT) by solid-liquid extraction.

[Formula]

MBT is a rubber vulcanization accelerator and a compound which is a raw material of various other rubber vulcanization accelerators. The MBT manufacturing method is known as the Kelly method and is described in detail in US Pat. No. 1,631,871.

Since US Pat. No. 1,631,871 several techniques have been known which have improved the manufacturing process of the Kelly process.

However, known techniques, that is, MBT manufacturing methods based on aniline, sulfur and carbon disulfide in a pressure vessel under high temperature and high pressure have a problem in that a solid waste amount of 15 to 20 wt% is generated.

Therefore, even in the case of a high-yielding method, if the main product MBT cannot be recovered, the yield is substantially reduced and thus the productivity is lowered, and the economic loss due to the treatment of the solid waste (tartic mixture) is enormous.

In order to solve this problem, the present invention uses a solid-liquid extraction method to recover only MBT from solid waste with high yield and high purity.

In general, the composition of the solid waste produced in the MBT production process is shown in Table 1.

Composition of solid waste compound Solid waste1 Solid waste2 MBT 30-32 20-22 Benzothiazol 8 to 12 3 to 5 sulfur 30-32 34-35 Other mixtures 24-32 27-43

In Table 1, solid waste 2 is a sample after distillation of about 10% of benzochiazole, and the composition of the other mixtures includes compounds such as aniline, carbon disulfide, dithiodianiline, aminothiophenol, and aniline benzothiazole. It is a mixture containing.

[Inventive problem to solve]

There is no known technique for recovering MBT directly from solid wastes (tartic mixtures) with respect to the MBT recovery method. However, there has been a description of a method for refining the solid wastes produced. US Pat. No. 3,031,073 and Japan Japanese Patent Application Laid-Open No. 53-9766 and the like are known.

The above known technologies are methods of purifying pure MBT by treating the reaction mixture, that is, solid waste by dipping carbon dioxide into carbon disulfide, or making a soda salt of MBT using caustic soda solution, followed by acid treatment, which is a fundamental solid waste. It's not a treatment.

In another way, the solid waste may be re-introduced into MBT production as an alternative to aniline and carbon disulfide, but it is only a limited method because it adversely affects the purity and yield of the produced MBT.

Accordingly, an object of the present invention is to quantitatively recover only MBT as an active ingredient in high purity by using a solid-liquid extraction method using a solvent having excellent selectivity from solid wastes generated during the manufacturing process of MBT in a general high temperature and high pressure vessel. To provide a way.

Composition and Action of the Invention

The solid-liquid extraction method used in the present invention uses solvents of lower alcohols such as methanol and ethanol, which selectively have solubility only in MBT among about 10 kinds of mixtures, and particles of about 50 to 200 mesh in order to maximize extraction efficiency. Pulverize.

Solid wastes consist of MBT, sulfur and many complex mixtures and are poorly soluble in common organic solvents except carbon disulfide, but have some solubility in polar organic solvents.

The solubility of various solvents is shown in Table 2. The results of the experiment showed that the solubility in solvents increased with increasing polarity, but the selectivity for MBT decreased, and the lower alcohols showed superior selectivity for MBT. Could.

Solubility of Solid Waste g / 100ml menstruum Solubility menstruum Solubility toluene 0.24 Acetone 0.24 benzene 0.08 Acetonitrile 0.05 Methanol 0.15 Dioxen 0.34 ethanol 0.24 DM 0.56

According to the present invention, the solid waste may be pulverized to a suitable size, extracted with a lower alcohol such as methanol, and then concentrated to obtain MBT from the solid waste at a high recovery rate. As shown in the electron micrographs of FIGS. 1 and 2, it was confirmed that the solid waste turned into porous particles after the MBT was extracted by the solid-liquid extraction method according to the present invention.

Selected embodiments of the MBT recovery method according to the present invention are as follows.

EXAMPLE

Example 1

3 kg of solid waste (containing 960 g of MBT) was ground to a 50 to 150 mesh size using a coarse mill, stirred in a 30 L reactor with 19 kg of methanol for 3 hours at 50 ° C., the filtrate was filtered and concentrated to give 940 g of MBT. Got. This compound is a pale yellow solid with a recovery yield of 98%. A liquid chromatogram analysis shows that the purity is over 95% and the melting point is 169 ° C.

Example 2

The solid waste was pulverized to 3 kg (containing 960 g of MBT) into a size of 50 to 150 mesh using a coarse mill, then stirred for 3 hours at 50 ° C. with 19 kg of ethanol in a 30 L reactor, and the filtrate was concentrated after filtration. Obtained MBT. This compound is a pale yellow solid. The recovery yield is 99%. The liquid chromatogram analysis shows that the purity is over 95% and the melting point is 170 ° C.

Example 3

Under reflux heating at boiling point using methanol under the same conditions as in Example 1, MBT 940 g (98% yield, 95% purity, melting point 169 ° C) was obtained with 95% purity (melting point 169 ° C).

Example 4

MBT 950 g (yield 99%, purity 95%, melting point 169 ° C) was obtained by reflux heating at the boiling point using ethanol under the same conditions as in Example 2.

Example 5

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a mill, and then 12.5 kg of methanol with 4 kg of water was heated to reflux with stirring in a 30 L reactor for 3 hours. After stirring, the filtrate was filtered and concentrated to obtain MBT of 601 g (recovery yield 94%, purity 95%, melting point 169 ℃).

Example 6

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a mill, and then 12.5 kg of ethanol was heated with reflux with stirring for 3 hours in a 30 L reactor with 4 kg of water. After stirring, the filtrate was filtered and concentrated to obtain 608 g (95% yield) of MBT. The result of liquid chromatogram analysis showed that the purity was over 95% and the melting point was 169 ℃.

Example 7

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a mill, and then 12.5 kg of methanol with 5.3 kg of water was heated under reflux with stirring for 4 hours in a 30 L reactor. After stirring, the filtrate was filtered and concentrated to obtain 580 g (92% yield) of MBT. The liquid chromatogram showed a purity of 96% and a melting point of 170 ° C.

Example 8

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a mill, and then 12.6 kg of ethanol was heated to reflux with stirring for 5.3 hours in a 30 L reactor with 5.3 kg of water. After stirring, the filtrate was filtered and concentrated to obtain 590 g (92% yield) of MBT. The result of liquid chromatogram analysis showed that the purity was over 96% and the melting point was 170 ° C.

Example 9

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a mill, and then 12.5 kg of methanol with 8 kg of water was heated to reflux with stirring in a 30 L reactor for 5 hours. After stirring, the filtrate was filtered and concentrated to obtain 570 g (89% yield) of MBT. The liquid chromatogram analysis showed that the purity was over 97% and the melting point was 170 ° C.

Example 10

2 kg of solid waste (containing 640 g of MBT) was ground to a size of 50 to 200 mesh using a pulverizer, and then 12.6 kg of ethanol was heated with reflux with stirring for 5 hours in a 30 L reactor with 8 kg of water. After stirring, the filtrate was filtered and concentrated to obtain 576 g (90% yield) of MBT. The liquid chromatogram analysis showed that the purity was over 97% and the melting point was 170 ° C.

[Effects of the Invention]

The method according to the present invention can improve economic efficiency by dramatically increasing the yield of MBT, and at the same time, it is useful for preventing environmental pollution due to excellent waste treatment effect.

Claims (5)

In the method of recovering MBT from solid waste generated in the process of preparing the vulcanization accelerator 2-mercapto benzothiazol, the solid waste is pulverized into particles of a certain size, and then dissolved by stirring with a solvent having a selective solubility, followed by appropriate temperature. Concentrating under conditions, MBT recovery method characterized in that to selectively recover only MBT having the following structural formula. [Formula] The MBT according to claim 1, wherein the solid waste is a by-product of the process of preparing 2-mercapto benzothiazol, a vulcanization accelerator, and is a mixture of sulfur, 2-mercapto benzothiazole, and various organic compounds. Recovery method. 2. The method of claim 1, wherein the particle size is 50 to 200 mesh. The method of claim 1, wherein the solvent is any one of polar organic solvents such as methanol, ethanol, water and acetone, and the solvent includes a combination solvent such as methanol / water or ethanol / water. . The method for recovering MBT according to claim 1, wherein the appropriate temperature is 50 to 100 ° C.